Traditional Archery Discussions on the Leatherwall


Accuracy of bow weights?

Messages posted to thread:
Renewed Archer 07-Sep-17
gluetrap 07-Sep-17
ny yankee 07-Sep-17
PEARL DRUMS 07-Sep-17
Renewed Archer 07-Sep-17
Jeff Durnell 07-Sep-17
2 bears 07-Sep-17
RymanCat 07-Sep-17
ModernLongbow 07-Sep-17
Longcruise 07-Sep-17
George D. Stout 07-Sep-17
Longcruise 07-Sep-17
dean 07-Sep-17
George D. Stout 07-Sep-17
bowfitz 07-Sep-17
zog 07-Sep-17
zog 07-Sep-17
zog 07-Sep-17
zog 07-Sep-17
fdp 07-Sep-17
The Whittler 07-Sep-17
buster v davenport 07-Sep-17
GLF 07-Sep-17
kginrick 07-Sep-17
zog 07-Sep-17
2 bears 07-Sep-17
yorktown5 08-Sep-17
Rick Barbee 08-Sep-17
GF 08-Sep-17
Renewed Archer 08-Sep-17
Longcruise 08-Sep-17
GLF 08-Sep-17
dean 08-Sep-17
Renewed Archer 08-Sep-17
ModernLongbow 08-Sep-17
fdp 08-Sep-17
Renewed Archer 08-Sep-17
bradsmith2010santafe 08-Sep-17
Renewed Archer 09-Sep-17
Shawn 09-Sep-17
ModernLongbow 09-Sep-17
GLF 09-Sep-17
Renewed Archer 09-Sep-17
Dogman 09-Sep-17
GLF 09-Sep-17
dean 09-Sep-17
Jeff Durnell 09-Sep-17
kginrick 10-Sep-17
fdp 10-Sep-17
kginrick 10-Sep-17
arrowchucker 10-Sep-17
Renewed Archer 10-Sep-17
goldentrout_one 10-Sep-17
Shawn 10-Sep-17
dean 10-Sep-17
Renewed Archer 10-Sep-17
Joe2Crow 10-Sep-17
fdp 10-Sep-17
George Tsoukalas 11-Sep-17
GLF 11-Sep-17
johnjwert 11-Sep-17
johnjwert 11-Sep-17
johnjwert 11-Sep-17
johnjwert 11-Sep-17
johnjwert 11-Sep-17
bowfitz 11-Sep-17
Longcruise 11-Sep-17
zog 11-Sep-17
Red Beastmaster 12-Sep-17
Longcruise 13-Sep-17
Longcruise 13-Sep-17
Longcruise 13-Sep-17
Longcruise 13-Sep-17
Longcruise 13-Sep-17
Brad Lehmann 13-Sep-17
Longcruise 13-Sep-17
Renewed Archer 13-Sep-17
jaz5833 13-Sep-17
jaz5833 13-Sep-17
jaz5833 13-Sep-17
Jeff Durnell 14-Sep-17
Jeff Durnell 14-Sep-17
GLF 14-Sep-17
Renewed Archer 14-Sep-17
Jeff Durnell 14-Sep-17
Renewed Archer 14-Sep-17
Renewed Archer 14-Sep-17
Longcruise 14-Sep-17
GLF 14-Sep-17
MStyles 14-Sep-17
johnjwert 14-Sep-17
Jeff Durnell 14-Sep-17
dean 14-Sep-17
johnjwert 14-Sep-17
johnjwert 14-Sep-17
johnjwert 14-Sep-17
Renewed Archer 14-Sep-17
Longcruise 14-Sep-17
Renewed Archer 15-Sep-17
Longcruise 15-Sep-17
Renewed Archer 15-Sep-17
Longcruise 15-Sep-17
From: Renewed Archer
Date: 07-Sep-17




The accuracy of actual bow draw weights is important to me. B/c of back problems I select bows of varying weights so I can shoot the weight I can handle on any given day. But like most here, I've found that AMO listed weights are often wrong even for new or relatively new bows, and almost always for vintage bows. Also when I am buying a bow I try to get the seller to measure the actual draw weight. If they do, most of the time I find it's not the same as when I measure it. For example one guy had a 36# bow that he swore scaled 42#s @29" with his digital scale. When I got it, it measured 35# on a cheap luggage scale that was accurate to within 1#. A friend had a couple of bows scaled at two archery stores and they both came in 2-3#s over other scales... one done by the bowyer a week earlier.

I've come to not trust what other people say a bow's weight is. I also got a new Salter Breknell analog scale that measures in increments of 4 oz. and is accurate to 1 in 250... whatever that means. I've been re- measuring my bows and getting more accurate weights. Of course they shoot the same regardless of how they scale.

What's with the big variation in how bows scale? What's the best way to scale a bow? What's been your experience? Or does it matter to you?

Shandor Weiss

From: gluetrap
Date: 07-Sep-17




imo a bow that is with in ilb in either direction is perfect. most are more than stated. I would rather they be less than stated, no matter what scale you use if the bow is too heavey,it is too heavey. if a person who shoots a 60lb bow says the for sale is 40lb...take that with a grain of salt..ron

From: ny yankee
Date: 07-Sep-17




It matters a lot for correct spine. I'm going to buy one of those nice little digital ones and make a tree to scale bows. Don't know why I haven't a long time ago.

From: PEARL DRUMS
Date: 07-Sep-17




Unless we all used certified scales that are calibrated yearly, we will rarely get the same numbers.

From: Renewed Archer
Date: 07-Sep-17




I agree within a pound is accurate enough. And it is important for selecting arrow spine, but at least with arrows you can try them to see what works. More easily than changing bows or altering a bow.

I made a stringer on a post w/pulleys and a hand crank winch. Works great, you can stop at any length of draw, check the bow, limbs and string, see the draw force curve... or chart it. I think that drawing slowly to full draw helps accuracy also, but I'm not sure. If someone draws quickly with a scale there may be some additional force exerted by acceleration. I don't use a digital scale but I wonder if some of the false readings are from that. Force = Mass X Acceleration - Newton.

From: Jeff Durnell Professional Bowhunters Society - Associate Member
Date: 07-Sep-17




Scales can vary, but I also wonder if people are measuring them by the same method... 26 1/4" to the deepest part of the grip, 28" to the back of the bow, to their own draw length, or whatever...

From: 2 bears
Date: 07-Sep-17




The method of measurement seems to cause the most variation. The most popular way seems to be to the back/target side face, of the bow. That is not the standard and bow risers differ in width a lot. >>>----> Ken

From: RymanCat
Date: 07-Sep-17




Variables I say this a lot. That's the world we live in. You get a bow home and check it on your scales what you have and its not what the bowyer said and wrote on bow. Its all variables in life so if your going to try to be exact you can't and better get over it and realize that.

I have had them easily vary 5 pounds already and feel like it as well. If I had to be so close to a weight then I'd be not able to shoot the bow I guess.

Deepest part of grip gives you brace not arrow length. Front of bow to the nock at the string edge gives the length.

Take an arrow and mark it what draw you want to achieve then scale the bow even on hand scale will get you close.

No need to wonder woman just do it correctly and learn that!

From: ModernLongbow
Date: 07-Sep-17




I have a very good quality easton bow scale. I draw exactly 28". Never measured a bow that was more than 1# off the marked weight. 99% have been spot on. I usually only shoot newer bows though. I hear stories of older bows being way off but could not confirm that. I have tested a LOT of bows.

From: Longcruise
Date: 07-Sep-17




All of my vintage bows come in well under what they are marked. I think they lose weight over time.

I regularly check my scale by hanging known weights on it and it's always right on. The other day I shot a brand new bow from a well known and reputable bowyer that was marked 47# and scaled 41#. This bow was the same weight measured AMO and to the back since it measures 1.75" from the deep point of the grip to back.

It was obvious the first time drawn that it was light.

Nonetheless, it's a fine shooting bow.

From: George D. Stout Compton's Traditional Bowhunters
Date: 07-Sep-17




My experience is different as most of the vintage bows are right about on the nose. I'm not all that fussy though and expect that if it's within two or three pounds I can adapt easily, and it won't affect arrow spine all that much. If two pounds affects your spine, you likely were on the edge of the next spine anyway...up or down.

My scale is on a 2x6...and lays on a table so the mass weight of the bow isn't a factor. I measure it to the back of the bow at the shelf. No, that isn't AMO but it is close enough to know what I need to know. I pull my arrows to the back of my bow so that is the relevant measure to me.

I have noticed that some vintage models can show heavier, but scales vary...as mentioned. All of the vintage bows I have right now...4 of them...are within a pound of marked weight when I measure them to the back of the bow at the shelf.

From: Longcruise
Date: 07-Sep-17




Here's two vintage that vary a lot

DH Cavalier. Marked 55#. Scales 44#

Shakespeare Necedah marked 40#. Scales 34#

From: dean
Date: 07-Sep-17




Arrow spines are not measured to the belly of the grip, if our draw lengths concerning arrow lengths are measured to the back of the bow, there is no point to measuring bow weights from the belly of the bow. I think that this is a break down in the objective logic of the AMO. Anyway, I make a rope duber that mimics fingers on the bow string. I hang weights on the bow string. In this area we have one archery shop that is consistently 2% under my weights and another that is 2% over my weights, one measures 49 pounds with a 50 pound bow and the other measures 51 with a 50 pound bow. They both claim to be dead on, I must be more dead on than they are. The reason so many Hills were measuring on the heavy side is that Craig was using his bow scale sideways, that was creating a friction drag some where. When measuring with a hanging scale, one must hang the bow from the string, because if the bow is hung by the bow on the scale, the weight of the bow will add to the number. Hanging by string merely adds the bow's weight to the scale and represents the bow's draw weight at the distance that the bow's physical weight pulls the string.

From: George D. Stout Compton's Traditional Bowhunters
Date: 07-Sep-17




Yes, I would say that was a definite miss mark from the factory. Maybe a 3PM Friday output.

From: bowfitz
Date: 07-Sep-17




This is what i think is happening here, bowyers measure from different places the back of riser,middle of riser ,deepest part of the grip,giving big differences.Check it out yourself,measure one bow in three different spots.

From: zog
Date: 07-Sep-17

zog's embedded Photo



A quick web search on the correct way to measure draw length resulted in three different ideas in about two minutes, all from people who seem to do this a lot.

From: zog
Date: 07-Sep-17

zog's embedded Photo



From: zog
Date: 07-Sep-17

zog's embedded Photo



From: zog
Date: 07-Sep-17




One says measure to the belly of your grip, the next says add 1 inch to that, the next says add 1-34 inch to that. Wouldn't that make a difference of about 3-4 pounds pull?

From: fdp
Date: 07-Sep-17




The bottom one is the AMO method zog. 26.25" from the pivot point. The arrow length and the draw length aren't the same.

And the plus 1.75" only works if the self is 1.75" from back to belly. That's whay the AMO standard was implemented.

Pretty simple really.

From: The Whittler
Date: 07-Sep-17




I have watched some videos on bowyers and some just hook the bow up and give a couple yanks on the pulley at around 28" and call it good.

Or give you what you ask for no matter the weight. Not all bowyers do this just some.

From: buster v davenport
Date: 07-Sep-17




When I started out in the late '50s, I don't recall seeing any one measure the weight of their bow. When we bought a bow from a shop and it said 45# or whatever on it, we took that to be what it was. bvd

From: GLF
Date: 07-Sep-17




When you hang the bow from the scale to check weight remember to subtract the bows mass weight to get the correct draw weight. Guys will complain their bow is 4 lbs over when in reality the bow weighs 4 lbs and the draw weight is on the money. Oh and unless your shooting carbons a couple lbs bow weight makes no difference in spine if you got the right arrows to start with.

From: kginrick
Date: 07-Sep-17




When you hang a bow on a scale by the string the limbs will flex by the weight of the bow, and the bow will be drawn to that weight. The string will deflect the same as if you held it in your and drew it to 2 pounds (with a bow that has an actual 2 pound mass weight) is . So you will not get any additional weight added to your end result . Simple physics no need to subtract the weight.

From: zog
Date: 07-Sep-17




Thanks fdp. However my point was not to see which one is "correct", the point is that different archers are using different ways to measure the 28". So unless you are careful to ask what someone really means when they say 28", you could wind up with a draw weight that is 3-4 lbs different than what you thought you are buying.

From: 2 bears
Date: 07-Sep-17




And now you know the reason for the variation in weights. All of my bows 40 years old and over check with in a pound,when measured correctly. I personally measure like George for the simplicity of it and getting my arrow length right. The proper AMO way as stated, is 1 3/4" past the arrow rest. Technically the rest should be at the deep point of the grip which farther confuses the issue, because some are some are not. Most Re- curves measure pretty close to the bow back. The exceptionally wide risers and the skinny self and long bows throw things out of kilter.As George said it is not enough to cause your arrows to be miss-spined. When you want to compare with others ask where they measured the weight.Then you will most likely agree.>>><----> Ken

From: yorktown5
Date: 08-Sep-17




For whatever its worth, I've given up on finding a consistent answer to why the variances between them's thats doing the measuring' and the bow.

Instead, I simply put the scale on the string and draw the bow to MY anchor/release point. That result is what I use for arrow tuning.

Rick

From: Rick Barbee
Date: 08-Sep-17




What yorktown5 said.

I've found digital crane scales to be the best/most accurate for checking draw weights, and they come in real handy for other things (like weighing animals) too.

Mine is a 600# rated scale, but it accurately weighs to 650#.

Rick

From: GF
Date: 08-Sep-17




I'd have to agree with Rick & Rick...

All that really matters is that YOU use the same scale and the same method for every bow.

That might make it a bit more difficult to buy a bow sight- unseen, but when I was born, they hung out a big sign that said "Welcome to Reality" and I've been living happily enough here ever since....

And FWIW, I can't imagine that a couple of pounds either way would be critical unless the shooter has exceptionally good form and is already much too close to being overbowed in the first place; 1/2" of draw - on most of the bows we shoot here - is worth a pound and a half or more; translate that into give- or-take-1/4" at full draw and most would need a clicker to be that precise.

From: Renewed Archer
Date: 08-Sep-17




Rick, Rick, and George... and others... good points. I measure at my draw to the back of the bow also. What I want is my actual draw weight and I can't see anything being more accurate than drawing the arrow to my actual draw length!

My interest is only partly for choosing arrow spine. That choice is not just bow weight but many factors and has to be tested with shooting. I'm mostly concerned with how much it takes to draw the bow so I can choose bows (when buying) or select bows to use (when shooting) based on how heavy a bow my back can handle on any given day. For my own bows as long as I am consistent scaling bow to bow, it's all relative so the weighing technique doesn't matter so much. But when buying a bow it's almost impossible to know what the weight will really be, unless I get it from someone I know and I know from experience how they weigh a bow and how their scale reads.

I guess the variables just make it impossible to know for sure ahead of time. Like Rick says.

Dean, great idea to pull the string with something that mimics fingers. I'm going to try that. I use a an arrow cut to my draw length, nocked on the string, to measure with. But pulling the string with a thin hook on the scale makes it hard to get the arrow in the right place. That sounds like the perfect solution.

Shandor

From: Longcruise
Date: 08-Sep-17




I marked a lath up to 32" and drilled it and hung it from the hook on the scale so the hook went through at zero on the scale. It's marked in inches and has a special mark at 26 1/4".

It's surprising how many bows are 261/4" at the deepest point on the riser and also 28" at the back of the bow.

From: GLF
Date: 08-Sep-17




+- 1 lb is a very new thing. Customs have always been 2 lbs either way and factory by amo which comes out to 2.5 either way. Unless it's a stacking sob I don't know anyone who can tell 2 lbs in 2 identical bows. Again as for spine you order the correct spine at your weight and the length you want with wood or aluminum and since carbon only has a few spines you buy one with your specs in its range and cut or add tip weight to make the spine you need. Personally I don't want a bowyers design altered on a bow I buy so if it's within reason I take it as is.

From: dean
Date: 08-Sep-17




So then, if it is a compound, 50 pounds is 28" to the deepest part of the grip and arrow length must be added accordingly. If it is a new fangled recurve 26&1/4" plus 1&3/4" added to equal poundage. If it is a custom Hill style longbow that is 50 pounds at 28", 50 pounds and 28" comes at the back of the bow at the arrow shelf and the belly measurement is ignored because the bows and arrows are built to accommodate the draw length of the user at their draw length and grip depths are measured from the back of the bow to accommodate the size of the user's hand. My wife can feel two pounds.

From: Renewed Archer
Date: 08-Sep-17




I can easily feel 2 pounds difference between the same model bow. Even less than that. In fact that's what I'm talking about. I have bows of the same model that are 2#s apart, and some days I choose to shoot the lighter one or vice versa. I could shoot the heavier one and even bows much heavier but I might pay for it later. Also if I (or anyone) is shooting a lot of arrows, e.g., 100, a 2# difference means by the end of the session I've "lifted" 200#s more or less. It adds up.

If you can't feel a 2# difference between bows, consider yourself fortunate!

On the other hand, my goal of having certain models in 2-3# increments gives me a reasonable (to me, at least) excuse to get more bows!

GLF, there is a difference, isn't there, between building a bow and trying to attain a certain weight, and measuring the weight once it's built? It's measuring the weight that is the issue here.

From: ModernLongbow
Date: 08-Sep-17




I need to retract my previous statement. Was weighing some bows today and I actually have a dwyer dauntless that is marked 50@28 and it scales 45@28 I triple checked. Thats actually great for me, but I guess someone who really wanted a 50lb bow was probalby upset.

From: fdp
Date: 08-Sep-17




There's different conversations taking place on this thread. Originally it was about the accuracy of marked bow weight. As has been mentioned, and as has been my experience, if you measure using the AMO method (which works for ANY bow period) then there is a standard method, and the are pretty dang close. It' reliable, and repeatable.

However, when you star making up ways to measure them, that's where things come apart. Measuring to the back of the bow, measuring to withn an inch of the back of the bow, those will never be consistently repeatable. It's works fine for us as individual's, but not som much in commercial or private sales transactions.

You don't ADD anything to get the poundage regardless of the type of bow. The 26.25" from the deepest part of the grip IS the draw weight per AMO standards. It's spelled out very clearly in their handbook.

Like I said earlier, this is an easy subject, but it sure does get made complicated.

From: Renewed Archer
Date: 08-Sep-17




fdp... I'm sure it is easy, but a lot of people who swear they are doing it correctly, as well as manufacturers, wind up w/bow weights that are not reproducible on tested scales. I've weighed a lot of bows using the AMO method also and it has come out almost exactly the same as measuring 28" to the back of the bow. But not the same as other people measuring it. I don't think that will ever change unfortunately.

From: bradsmith2010santafe
Date: 08-Sep-17




I measure my bows the same way,, and its repeatable and easy,,(the way Jim Hamm and Tim Baker taught me) I draw a mark of the arrow at the intended draw length,,or put a piece of tape,, I then draw the bow with a scale to that mark,, for example that bow is drawing 50# at 28 inches,,, drawn to the back of the bow,, thats how most wood bow guys measure draw weight,, back in the day if I was selling teh bow, I would explain how I measured the weight,,no problem,,

now I give my bows away,, I marked the last one to Jeffer as 50ish and 29 1/2 he was pretty easy and said anything in the 50# range was ok,, thats the kind of client you want to have,,:) I am not sure if he ever weighed it or not,, I was expecting some weight change from climate to climate,,,

if you think your way of wieghing a bow is the best,, then weigh the bow and mark it accordingly,, its your bow,,:)

From: Renewed Archer
Date: 09-Sep-17




Hey, that's a good idea. I don't know why I didn't think of that. Just mark the bow with the weight I get. I have it written down in a file but it's far easier to just look at the bow and see own actual draw. Thanks.

From: Shawn
Date: 09-Sep-17




I have been doing this for over 40 years and I have yet to meet a anyone and am talking hundreds and hundreds of shooters that can tell the difference between 45 and 47#s of draw weight. Shawn

From: ModernLongbow
Date: 09-Sep-17




Shawn, i can but we have never met :)

From: GLF
Date: 09-Sep-17




Only thing i can think is a person would have to be on the verge of being overbowed to be able to feel a 2 lb difference. Or maybe its just a thing with peope who shoot light bows. Since 2 lbs is a higher percentage of 40 than it is 60 or 70

From: Renewed Archer
Date: 09-Sep-17




Shawn, GLF, you left out a group. People with back injuries. I have 2 compression fractures. Have lost 2" of height. To compensate my mid to lower back muscles are extremely tight, to sort of hold me in place or together. Sometimes on the verge of spasms. It's painful all the time, just sometimes I ignore it better than other times. Like when shooting... which actually helps it. But my point is, since my muscles are so tight all the time, any little extra strain on them is easily felt. Shooting uses mostly mid to upper back muscles but the lower muscles are used also, to stabilize the body and upper back and neck.

I've also had to learn to gauge any activity in terms of how it affects my back, and to avoid those that cause more pain. So I guess you could say I've been training my muscles to give me feedback. Or vice versa.

The result is that I can EASILY feel a 2# difference in bow weight. Even less. With light bows or heavier bows, although the heaviest I've tried is 50#.

You often won't meet people with chronic back pain b/c they tend not to travel or go to events.

Shandor

From: Dogman
Date: 09-Sep-17




The trouble is there are many correct ways to measure a bow. The AMO method, measuring from the string to the back of the bow. Often people will hang a bow from the scale and pull down 28" to measure without taking into account the weight of the bow (and some recurves are heavy) Even a longbow will generally weight between 1.25# & 1.50#.

From: GLF
Date: 09-Sep-17




Ouch! Man sorry to hear about your back guy. With something like that you do what you gotta.

From: dean
Date: 09-Sep-17




My wife wife can tell the difference between 38 and 40 pounds at her draw. She wanted her bows to pull the same, I trimmed a bow down and drew it and thought they were the same. She drew them and said, 'not quite there yet.' I weighed them and she was right. When I was shooting bows over 80 pounds most of the time, I could not tell the difference in my bows from 79 to 89 pounds, but when I would shoot a 50 pound bow I would jerk it back clear past my anchor with no control. My son mostly shoots a 59 at 27 Robertson longbow and another that is 57 at 28draws just shy of 28. I let him shoot my new Sunset Hill, which 55 at 26, he declared to be much lighter than his Robertsons, I think they feel about the same. Then he told me how the wood arrows that he made didn't shoot out of his bows. From about 22 yards, he shot six arrows into something less than a baseball with his lighter Robertson, every arrow flew perfect. Then from the same distance shot a much tighter wad with my Sunset. He declared that some very serious thought went into a bow that could do that, being that it is not a center shot bow at all and not feel like it was pulling as hard as it was marked and still shoot those stiff arrows so well. I had to weigh the bows to prove my point. I always weigh bows in relation to the arrow length, the back of the bow. I do not care what industry standards are when I make arrows for people, I just need to see them shoot and check the bow weights and tuning.

From: Jeff Durnell Professional Bowhunters Society - Associate Member
Date: 09-Sep-17




People check draw weight different ways, and then are surprised when their readings are different than what's marked on the bow. Shocking aye?

From: kginrick
Date: 10-Sep-17




I will repeat the weight of the bow does not add to draw weight . When hung from the string the string is being draw to the weight of the bow . It may only require 1/2" of draw to achieve this . So unless you actually hang the bow then draw an additional 28" you will not add a thing to the draw weight , but then you would be drawing 28 1/2" not 28"

From: fdp
Date: 10-Sep-17




Francis, you want to explain that? Because if you hang a 4lb. bow on a scale by the throat of the grip, the limbs don't bend, and it does indeed add 4lbs. to the draw weight of the bow.

Now, of you hang the 4lb. bow on the scale by the string, so the limbs can flex as you mentioned, it would have a minimal affect.

From: kginrick
Date: 10-Sep-17




Frank the second sentence states when hung from the string . In which case the effect is zero not minimal . I have never attempted to check the weight by hanging the bow from the riser. I find it makes more sense to hang from the string and pull the bow down to a marked draw length with a marked arrow.

From: arrowchucker
Date: 10-Sep-17




I know a well known bowyer who will remain anonymous that tried to hit weight but he Always wrote whatever you asked for on the bow. No mater what is was. His bows are great, I've. Had him build 3 for me and didn't care if it was off some. You want 43 1/2# at 26 3/4". That's want it said,. Everyone was spot on. Most bow scales are so bad nobody can tell any difference.

From: Renewed Archer
Date: 10-Sep-17




"Most bow scales are so bad nobody can tell any difference." That's what I've been wondering! I know there are different ways to weigh a bow but if the scales are all off it will be hard to get weights that agree with each other. You would think digital scales should be more accurate but I've seen them be far off also. That's why, for myself, I got a high quality analog scale.

Maybe people just don't care that much what a bow really scales at. As with other things. Does it matter if a clock or watch is a couple of minutes off? Does it matter if a tire pressure gauge is off a couple of pounds? A thermometer? So many of our measuring devices are made so cheaply these days, we are probably getting inaccurate measurements of many things. I can think of one tool, though, that no one wants to be inaccurate. A tape measure. An old fashioned tool that's simple. Like an analog clock or scale.

From: goldentrout_one
Date: 10-Sep-17




I have a 1969 super kodiak, marked 45 lb, but is actually 53 lb (and it's marked 53# under the strike plate!).

From: Shawn
Date: 10-Sep-17




Jeff he means he can tell by just drawing a bow and again I say BS! 3-4#s then I would say maybe but a pound or two is doubtful. I can tell the difference if a bow is heavier but it would have to be 4 or 5#s at least for me to be close on a guess. Shawn

From: dean
Date: 10-Sep-17




When the bow string is hung on the scale the bow's physical weight has no effect on the scale reading. I weigh bows with iron scaled weights with a yardstick arrow on the string to check drawn length at the shooter's draw length. The weight of the bow would then effect the total, so I hang my weight spindle from the string. We compared those little digital jobs, that read out number may look to be factual, but it often is not. Three little digital scales and three different numbers.

From: Renewed Archer
Date: 10-Sep-17




goldentrout_one... I had a 67 SK that was rated 47# and measured 52# on my scale. I put a new plate on it but there were no markings under the old one. I've heard of that, though. Good to check under the plate but you can't see there if just looking at pics of a bow in an ad.

Shawn... I guess you're calling me a liar then also b/c I can tell a 1-2# difference in bows. Let's keep the judgment down and the language civil. We are all different so I don't see why you think just b/c you can't tell, no one else can. I suppose you can't hit a prune off the top of someone's head shooting a broadhead... or wouldn't try... but Howard Hill did. But based on your reasoning he should not have been able to do it.

Dea... that's a cool way to scale a bow. Even more basic than an analog scale. I've become very suspicious of digital scales and devices. Just b/c it's digital doesn't mean it's accurate.

From: Joe2Crow
Date: 10-Sep-17




I don't think digital scales are nearly as inaccurate as some of you guys suggest. I just bought one at ETAR and started measuring a bunch of my recurves, vintage and custom. And I must say it confirmed what I suspected about the weight of my bows. For example, I have a Browning Explorer 1 that is marked 60# but pulls much easier than that. It scaled 54#. My Hoyt Pro Hunter is marked 51# but I always suspected it was heavier. It scales 54#. My TT recurve scaled 2# less than marked with both sets of limbs but it has the widest riser of all my recurves, and I was measuring to the back of the riser. An old Root Gamemaster and Shakespeare RH200 that are both marked 50# scaled with 1# of that. I think they are very useful tools. My next toy will be a chronograph.

From: fdp
Date: 10-Sep-17




The accuracy of the scale is only part of the equation. You HAVE to measure the draw weight the same way as the other guy did, And to be right on the money, you have to do it with a scale that is calibrated to the other guys scale, or accidently or on purpose.

From: George Tsoukalas
Date: 11-Sep-17




Why not ask the bowyer, if possible, how the draw weight was measured? Jawge

From: GLF
Date: 11-Sep-17




From: johnjwert Professional Bowhunters Society - Associate Member
Date: 11-Sep-17

johnjwert's embedded Photo



Gentleman, I help archers find limbs at the weight they want at their specific draw length on a daily basis. It isn't hard to do but it's important to communicate effectively during the process. To communicate effectively we need to speak the same language and I help archers understand the AMO standards and why we use the standards.

"AMO Draw Length Standard A. For Manufacturers Draw length is a specified distance, or the distance at the archer's full draw, from the nocking point on the string to the pivot point of the bow grip (or the theoretical vertical projection of a tangency line to the pivot point parallel to the string) plus 1 3/4"."

What this means is a 28" draw is when we draw an arrow shaft to 26.25" to a vertical line through the riser at the deepest part of the grip. For risers with a plunger hole this line typically bisects the center of the hole.

It's very easy to see why the standard was worded this way. Risers often have very unique designs. Longbows can be very skinny through the risers sight window while some recurves are extremely braod through the window. If we pull an arrow 28" to the "back" (edge nearest the target) of the bow we're not comparing apples to apples.

In the two pictures below you can see exactly what I mean and why the using the standard is the only good way to talk about draw length and draw weight.

From: johnjwert Professional Bowhunters Society - Associate Member
Date: 11-Sep-17

johnjwert's embedded Photo



From: johnjwert Professional Bowhunters Society - Associate Member
Date: 11-Sep-17




Hope you find this helpful despite the poor editing.

From: johnjwert Professional Bowhunters Society - Associate Member
Date: 11-Sep-17




As you look at these two images assume that this is the same person drawing each bow. He is an archer with perfect form who draws exactly the same length every time. If we use the back of the bow as a reference point (edge nearest the target) we might assume that with one bow he has a 29.5" draw length and with the other bow he draws barely past 27.5". That is obviously incorrect as we can clearly see the arrow is being drawn to the exact same point with respect to the archers bow hand position. This archer, by the AMO standard, has a perfect 28" draw.

From: johnjwert Professional Bowhunters Society - Associate Member
Date: 11-Sep-17




And one other thing...

The bow's mass weight is irrelevant. The mass of the bow is simply helping you pull down. To easily understand this check your bow's draw weight at 28" using the AMO standard. With a hanging scale pull a measuring arrow to 26.25" to the line bisecting the deepest part or your grip.

Then do it again with a 5#, 10#, or 20# weight hanging from your riser. You're going to get the same draw weight give or take a fraction of a pound.

From: bowfitz
Date: 11-Sep-17




very good John,thanks that should clear it up

From: Longcruise
Date: 11-Sep-17




John, I have always suspected that the weight of the bow would not have any effect on the actual draw weight. But now that you have presented such a simple test I just gotta try it.

I appreciate all the mental stimulation by all involved here.

Good topic.

From: zog
Date: 11-Sep-17




I used to teach physics. I often found it is easier to grasp a concept by picturing an exaggerated case. To show that the weight of the riser has no effect on a draw weight test:

Lets make a riser from lead - it'll weigh 30 lbs. Now attach some limbs that weigh 1/2 lb each, string it up then and hang the bow on a hook scale by it's string. The riser will pull down on the limbs, which will flex to maybe 18 inches of draw and the hanging scale will read 31 lb. Now hang weight from the grip until the bow flexes to 28" draw. Say that took 20 more lbs of hanging weight. The scale will now read 51 lb.

Now take this bow off the scale and set it sideways on a bench with a pin to hold the grip from moving. Draw it horizontally to the same 28". You will be pulling 51 lbs straight back.

From: Red Beastmaster
Date: 12-Sep-17




In thirty years of shooting stickbows I have never checked the draw weight. Just don't care.

From: Longcruise
Date: 13-Sep-17




OK! Here is the test of John's post stating that the weight of the bow will increase the measured draw weight of the bow by the actual physical weight of the bow.

Some suggest that you must subtract the physical weight of the bow from the measured draw weight when measured by hanging the bow by the string and pulling the bow down on the scale hook.

John maintained that regardless of the physical weight of the bow that the draw weight would not be increased by that amount when drawn down.

I used an ASL that I know draws 44# at 28" measured at the back of the bow. This bow just happens to also be drawn to 28" AMO when measured at the back.

I knew in advance that it would measure 44#, but I did the measure again for the sake of this test. Still at 44#!

Then, I hung ten pounds of weight from the riser and measured again. Lo and behold, the bow still comes in at 44#.

So there it is. Settled once and for all. Well, at least for me but the dispute will live remain alive on the LW I'm sure. :-)

From: Longcruise
Date: 13-Sep-17

Longcruise's embedded Photo



From: Longcruise
Date: 13-Sep-17

Longcruise's embedded Photo



From: Longcruise
Date: 13-Sep-17

Longcruise's embedded Photo



From: Longcruise
Date: 13-Sep-17




I said that backwards.

John contended that the weight of the bow would NOT increase the measured draw weight.

From: Brad Lehmann
Date: 13-Sep-17




The way my logic works, if you have a fifty pound draw weight and the physical weight of the bow is 2 pounds, it would take 48 pounds of force to pull the bow down or 52 pounds to pull it up. But I don't have a diploma to back up my logic.

From: Longcruise
Date: 13-Sep-17




That view has a certain intuitive ring to it and I would not have considered argueing against it just based on my gut feeling.

But seeing and doing is believing.

From: Renewed Archer
Date: 13-Sep-17




I don't have diplomas in physics but I took it in high school!

Brad, I think you now have a LW diploma. Or an archery diploma.

I think I can help make sense of this phenomena about the weight of the bow. The bow is rigid. It holds its own weight up in any position. What's being measured when the limbs are drawn is the potential force in the limbs when they are flexed. Or put another way, how much it takes to bend the limbs to full draw position. This has nothing to do with the weight of the riser or even the weight of the limbs. If you were to hang weights off each limb tip, that might affect the measurement if it is enough weight to make the limbs bend. Longcruise, why don't you try that and tell us the results? My guess is, it wouldn't make any difference. Just as the brace height of a bow does not change its draw weight. To get the bow to full draw it should take the same amount of force, regardless of where the limb tips are when you start.

Shandor

From: jaz5833
Date: 13-Sep-17

jaz5833's embedded Photo



Here's what I use and the method I use. It corresponds perfectly with every bow I've ever had within one pound.

The scale is for weighing luggage and has a follower needle to indicate the weight after removing the weight. It was $6 at a local discount store.

From: jaz5833
Date: 13-Sep-17

jaz5833's embedded Photo



From: jaz5833
Date: 13-Sep-17




Correction, I didn't think about that drawing enough. I would pull 28" to the front of the riser.

From: Jeff Durnell Professional Bowhunters Society - Associate Member
Date: 14-Sep-17




Like Zog said, in order to make truth obvious, it often helps to exaggerate. Imagine this......

If you had a bow that drew 50# @ 28"..... and the bow itself physically weighed 50 pounds.... and you hung it by the string, it would draw itself to 28"... without you pulling down on it.

If instead it physically weighed 25 lbs, you'd have to pull with only 25 lbs of force to reach 50# @ 28".

From: Jeff Durnell Professional Bowhunters Society - Associate Member
Date: 14-Sep-17




And so... coming back closer to the weights we are really dealing with... with a bow that physically weighs 5#, you'd need to pull down with 45 pounds of force to hit 50# @ 28".... but like the hypothetical bows above, you wouldn't need to subtract anything.

Same goes with a bow of UNKNOWN weight... hung by the string, or with the handle held fixed and scale hung on the string... or held by hand for that matter, just pull it to the proper length and check the scale.

From: GLF
Date: 14-Sep-17




Lol I'll just stick with the old spring scales. They're cheap and are accurate within a couple lbs and no ones gonna convince me that 2 lbs makes any difference unless you tell the guy theres a 2 lb difference. Then the imagination goes wild. But a guys not gonna draw a bow and say omg the bowyer missed my weight by two pounds,lol. Now if the bow is just 10 lbs , yes 2 lbs is easy to tell. that's also why custom bowyers only garrenteed +- 2lbs and why amo set up at 2.5. Custom bowyers in recent years found that some guys would pay extra money and didn't care how much the bows design was altered to shave it down to exact weight, whether it effected performance or not.

From: Renewed Archer
Date: 14-Sep-17




Jeff, I'm sorry to say but I think you're wrong about that. See the posts above yours about adding weights to a bow. The only thing that weighing a bow measures is how much it takes to bend the limbs. That has nothing to do with the weight of the bow itself.

Even if something were to draw the bow to 27", if it was a 50# bow, e.g., it would still take 50#s to draw the bow one more inch to 28". Isn't that your experience drawing a bow when shooting?

This topis is sort of interesting but it's not what the thread started out as... which is why bows measured by different people wind up with different weights. It is NOT because people do or do not add the weight of the bow itself.

From: Jeff Durnell Professional Bowhunters Society - Associate Member
Date: 14-Sep-17




You'd better read it again Renewed Archer, his post doesn't dispute what I said, it proves me right. He said the same thing I did, just worded it differently.

From: Renewed Archer
Date: 14-Sep-17




Jeff, I did read it again. Here is what Longcruise says:

"Then, I hung ten pounds of weight from the riser and measured again. Lo and behold, the bow still comes in at 44#.

So there it is. Settled once and for all. Well, at least for me but the dispute will live remain alive on the LW I'm sure. :-)"

Then I read what you wrote again: "And so... coming back closer to the weights we are really dealing with... with a bow that physically weighs 5#, you'd need to pull down with 45 pounds of force to hit 50# @ 28".... but like the hypothetical bows above, you wouldn't need to subtract anything."

I'm not really sure what you are saying, Jeff. First you say you would need to pull down with 45# of force to reach the 50# draw then you say you wouldn't need to subtract anything. So I guess you're saying that the weight of the bow itself doesn't matter, which as you say is in agreement with Longcruise's experiment. In that sense you are right and I misread what you wrote. But I think you are slightly wrong in saying that you would only have to pull down with 45#s of force since the weight of the bow is pulling down with 5#s. That only would be true if you were measuring the WEIGHT OF THE BOW but that's not what's being measured. What's being measured is how many pounds it takes to FLEX THE LIMBS until the draw is 28". That's different than bow weight as in a bow weighs 5#s.

I never thought much about these issues before but I have since reading this thread. I think the terms we use are confusing us. We equate bow weight with draw weight without defining either, except how to do it. The result is we get confused about things like whether to factor in the weight of the bow or not... since it seems counter-intuitive not to since we say we're measuring a bow's weight. The reality is we are not measuring a bow's weight. We are measuring a bow's limbs' draw force. How much force or weight does it take to bend the limbs to full draw. And as I said before, even if a bow was drawn to 27 and 3/4" by hanging weights on the limbs, if it was a 50# bow it would still take 50#s to draw it 1/4" more to 28".

So, everyone, what's the draw force of your bows compared to the draw force listed as the bow's AMO weight?

From: Renewed Archer
Date: 14-Sep-17




OK, sorry guys but I can't resist one more post. Please forgive me!

The weight of a bow, e.g., a bow weighs 5#s when placed directly on a scale, is the MASS (BM) of a bow. In scientific terms.

The weight of a bow, e.g., a bow weighs 50#@28", is the FORCE OR DRAW FORCE of bow limbs... assuming the riser does not bend.

Here's a simple equation:

DRAW FORCE (DF) = # OF LBS. TO DRAW BOW @ X INCHES - (BOW MASS X ZERO).

Pretty simple, huh?

As I said I don't have a degree in physics, but I did solve a physics problem in high school that no one else had solved in the teacher's 30 years of teaching. I may not be the brightest bulb and no doubt there's been some fading over the years, but I'm still not out.

From: Longcruise
Date: 14-Sep-17




The mass weight of the bow does reduce the amount of effort required to pull it down on the scale. IOW, when I did my little experiment with ten# of weight tied to the bow my own physical effort to pull the bow down was reduced by that ten#. But that says nothing about the actual draw weight of the bow. It's still a 44# AMO draw weight.

Another extreme example:

We have a TD bow that draws 50# AMO. The bow has excellent limbs and very effectively casts a 500 GPP arrow at 190 FPS. Now we place a call to the bowyer and order the identical riser but with a mass weight of 100# (hey, I said it was an extreme example LOL). We attach the limbs and go to the scale to check the draw weight. We find that in order to accurately check the draw weight at AMO we must support 50# of the mass weight of the bow. So, it's still a 50# AMO draw. When our super Man shooter puts an arrow across the chrono, it's still shooting 190 FPS.

What would be the correct draw weight of the bow with the 100# riser if it was the correct procedure to subtract the mass weight of the bow from the scale reading?

From: GLF
Date: 14-Sep-17




Jeff just explained the same thing in a different way is all. Both are saying the weight of the bow become part of the force bending the limbs not a separate entity so the weight of the bow is just doing some of the pulling for you. The bows mass pulls the first couple inches and you pull the rest.

From: MStyles
Date: 14-Sep-17




I had a Herter's Perfection that was marked 55# and was actually 63#. Also a pvc bow that was suppose to be 130# and stopped bending at 100#, then the bottom limb collapsed.

From: johnjwert Professional Bowhunters Society - Associate Member
Date: 14-Sep-17




Shandor, Mike's advice is 100% correct when we are pulling on a bow to measure draw weight in the same direction as gravity, straight down.

In that case our hanging scale is measuring the mass weight of the bow and the force applied simultaneously.

If we were measuring horizontally, on a table, then the mass weight of the bow is not applied to the force used to bend the limbs.

To demonstrate. I found the mass weight of a bow ~4.5#. I then attached the bowstring to a scale, I attached a second scale to the riser and I pulled downward on the second scale, in line with gravity.

The pictures below tell the story. The scale on the left was hooked under the bow, pulling downward. The scale on the right was hooked to the bowstring and this scale was hanging from a steel upright.

John

From: Jeff Durnell Professional Bowhunters Society - Associate Member
Date: 14-Sep-17




Yes GLF. That's what I was getting at.

Longcruise said, "The mass weight of the bow does reduce the amount of effort required to pull it down on the scale. IOW, when I did my little experiment with ten# of weight tied to the bow my own physical effort to pull the bow down was reduced by that ten#. But that says nothing about the actual draw weight of the bow. It's still a 44# AMO draw weight."

I concur with this as well.

From: dean
Date: 14-Sep-17




If there is no weight written on the bows, everyone's scales would be dead on.

From: johnjwert Professional Bowhunters Society - Associate Member
Date: 14-Sep-17

johnjwert's embedded Photo



From: johnjwert Professional Bowhunters Society - Associate Member
Date: 14-Sep-17

johnjwert's embedded Photo



From: johnjwert Professional Bowhunters Society - Associate Member
Date: 14-Sep-17




Shandor, after rereading it appears that you agree. I read that wrong.

From: Renewed Archer
Date: 14-Sep-17




Thanks everyone for your time and comments. I think we could go on endlessly talking about how much force is required to weigh a bow, whether vertical or horizontal, including or not including the mass of the bow. Although it seems everyone is nearing agreement.

Personally, I'm not really concerned with how much force it takes to weigh a bow by various methods. I don't even pull a bow down or up or sideways anymore. I use a hand crank winch! So for me it's no effort at all. LOL! Or just the effort to turn the winch handle.

My main point recently is that we say "weigh a bow" when really what we are talking about is the weight required to bend the limbs. We do already speak of the draw force curve of a bow... why not just call the weight of a bow it's draw force? Or for those who don't like to use 2 words, DF or just force.

I realize we're all going to continue using the term "weight" b/c everyone uses it. But thinking of it as draw force works better for me.

From: Longcruise
Date: 14-Sep-17




I've always referred to it as draw weight.

From: Renewed Archer
Date: 15-Sep-17




That's good, Longcruise. Sort of simple but better than just "weight".

What about draw force curves? Do you get into measuring or using that?

From: Longcruise
Date: 15-Sep-17




I do an FDC on every bow I build or get my hands on! :-]

From: Renewed Archer
Date: 15-Sep-17




Cool! How about starting a thread on that... how you do it, how you use the info, what you've learned?

From: Longcruise
Date: 15-Sep-17




I'll do that.





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