howdy folks,

about to start my first bow but need some help understanding taper since I've never bought one myself. I have ground out 12, .069 parallel maple lams and 10 .115 to .122 parallel lams to grind to tapers. I have parts to build the taper sled but haven't built it yet because I don't know where to start the taper. Some bows I own appear to start taper from bow center but one I own the taper starts outside the riser. To start taper from center I'd need a .117 lam for .003 taper for a 70" bow. If I start outside the riser the lam can be proportionally thinner. Those numbers are by memory so don't hold me too fast on them. Do I build the taper sled to be flat for the first 8" for a 16" riser or should the taper start from the bow center. This is for a "mostly" hill style bow. It has .125" deflex and .375" reflex from a flat limb line.

thanks, mark

In most regards, you are after a given taper and thickness in the active section of the limb. In that sense, it wouldn't mater where you started the taper inboard of the active section, so long as it is correct for your bending section. Though, if you start outside the grip cover it may be apparent, and it might in some very rare circumstance cause your riser/grip section to be under-structured.

Most important, if you grind from an outbound point, you must ensure the transition is smooth for a proper glue up.

Personally I just grind the whole lam tapered, even though it is a little more work.

One reason to start outboard would be if you were short the right lam thickness that you required for a particular, weight. Say you get requests for mostly 50# bows, and you get one for an 80#, and find yourself short. You can get the extra beef, by grinding from the outboard starting point (among some other more likely choices).

Bowlim, I guarantee you can't tell where my taper starts on a parallel/taper lam... unless you have just the single lam in one hand and a mic in the other. Even then, good luck guessin'. In a bow blank or even a finished bow, nope.

If I were you Wonderbowman, I'd build a simple, single taper lam sled. It can be used to make single taper lams, parallel/tapered, double tapered lams, and more.

I've ground lams both ways you mentioned... with a parallel section under the riser and then tapering toward the tips.... and with lams that are tapered their entire length.... bow center to tips. Which type I choose to make depends on many factors, but I don't think we need to get into a whole lot of depth with that right now. This IS your first bow, and what I'm about to tell ya will be more of a 'how-to' than a 'why-to' :^)

Tapering from center is a little more simple and straightforward, imo, and is where I would suggest you begin for your first bow... being that you're also grinding your own lams... for the first time.

You didn't mention if you were using full length lams, or lams that will be joined at their butts, that is, with their thicker ends joined with a scarf joint. No matter, I'll outline how I do butt jointed lams with a parallel portion in them in case that's the route you decide to go.

If it's a two piece/spliced lam, I cut and grind both pieces the same thickness, but a bit thicker than the thickness of the finished parallel section. It sounds like you may be at this stage now...???

Glue them together with a scarf joint and let them cure. Then grind this new 'one piece lam' until its thickness is precisely what you want the finished parallel portion to be. We now have a full length parallel lam that needs its tapers ground in each direction, fades to outer ends.

Use a pencil and draw a light line across the width of the lams in the two spots you want the tapering to stop... i.e. just beyond the ends of the fadeouts. Then draw a line from there down the length of the lam toward the tips just for reference... so as succeeding light passes are made with the thickness sander, while grinding in the taper, you can watch the leading edge of the taper remove your longitudinal pencil mark as it works it's way up the lam toward the 'stop mark'... the pencil line 'across' the lam. Stop when you get there. That's it. You're done. A parallel/tapered lam. If your lam sled is 4" or so wide, you can grind two at a time if they're to be of identical dimensions.

Does that make sense? It's actually pretty easy, accurate, and you don't need a special sled to make a par/taper lam.

If you have any questions at all, fire away. If you need me to post pictures or something, holla.

Now let's get some dust in the air!

I should have noted, I do this with a 40" lam sled. Grind one 'limb' of a lam, flip it end for end, grind the other end to match.... adjust the sander and repeat.

It's easy to take details for granted after they've become a matter of course :^) That's why I like to have new guys in the shop learning and quizzin' me. Keeps me thinkin' instead of just doin'.

Tim and Jeff, thanks. Jeff, makes perfect sense and sounds exactly like I imagined it. I'm using full length lams.

I'll start on the sled in the morning. I have 4" wide 1/2" osb. I cut a lot of parallel shims in thicknesses from .009 to .120. I'm going to place and glue them at the appropriate places along the length to form the taper. I'll have tapered lams by tomorrow.

Thanks again, mark

You're scaring me, Mark. I don't trust osb and shims for this.

Sorry, didn't mean to type osb. I use a lot of it and it was stuck on my mind. MDF with sandpaper glued on, and that part doesn't frighten me. If I need to I'll switch to BB latter. The glued in shims are just to form the taper between the 2 sheets of MDF.

Go for it. Check your work.

All I would add is that depending on the front view profile of the bow a .003 per inch taper is pretty aggressive.

Your sled needs to be at least 2'' thick for perfect tapers. Unless I am reading this wrong you said you were using 1/2''? I use micro lam with the grain running quarter sawn to the widebelt

Dang Frank! Here I was about to hit the rack and you go and unscrew the rails. Why? From everything I've read .003 is about standard for hill style bows. As close as I can tell my mountaineer is .003. I read more than one post about .005-.007 tapers but the math didn't add up to me unless I was building a 99# bow.

It depnds on the front view profile, and what you are wanting to end up with. Take for instance a lamination that is .100 on the butt end. Then taper it .003 per inch for 36 inches. See how thin the tip gets?

You CAN (again depending on other things) end up with a really whippy tipped bow.(bends too much in the outer 1/3 of the limb).Especially if you make the tips nice and small. I don't like them that way at all. I like a bow with a stiffer outer limb.

Yes, you have to be concerned with the overall taper as well, which means, you add them together. If you have 3 tapered lams in the bow, and each lam tapers at .003/1" then you have an overall taper of .009/1". That's a ton of taper in a longbow.

Tapering each lam .001/1" or .0015/1" is more common. Like Fdp said, depends on front profile, how you want the limbs to work, how many tapered lams are in it, etc.

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