Primitive Archer
Main Discussion Area => Bows => Topic started by: Stick Bender on November 22, 2017, 05:00:53 pm
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I was in the shop last night looking at staves to mill for laminates preferring to 1/4 saw but noticed for the most part I would end up with more slats flat sawn ,has any body noticed a huge difference in performance between the two and if so please explain my choices are osage,hickory,BL,maple, ash ?
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I think straight grain has less tendency to twist when drawn. As far as belly slats go I don't think it makes a lot of difference. I have heard 1/4 sawn is a little stiffer and flat sawn a bit more flexible. But I can't say I have noticed a difference.
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Thanks Steve ,Dean Torges (RIP) thought pretty much along the same lines as you , it just seems more economical in my case to flat saw but if there was a huge difference I would have 1/4 sawn , & in my case with osage it's hard for me to find a complete pin free peaces for 1/4 sawn !
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I think 1/4 sawn machines better if you are using any sort of taper grinder/planer (recent experience making Yew belly lams for Xbow prod)
Del
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Thanks Del I thought about that to ,but I usaly run the conveyer so slow and take off so little each pass & run 80 grit instead of 50 that you could shave & make dinner before it comes out the other side the last ones I got with in 2/1000s I'm trying to tighten it up but that's the best so far if I plane or joint I usaly run at a skew and it seems to make no differences but never tried yew or any other soft wood !
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Blimey, that shows how impatient I am. I was just dragging the sled through my planer/thicknesser in a matter of seconds! Mind I was just going by guesswork and eye, not any real tolerance. I guess the planer would be good to get to rough dimension and then a final pass through a sander/grinder... but that's only good if you have a big shop and a money pot for machinery.
BTW, do you need to stick down the lams when they go through? My planer is a bit vicious and so I stick 'em down with double sided tape... but then I have to get the damn stuff off afterwards >:(
All these labour saving machines, make a heck of a lot of work ::)
Del
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Man you just said a lot of isues I have been having I just did some horn lams and had to use the double back tape it is a pain in the orff! but with wood I don't have to use the tape just hold the butt end then as it's coming out the other side put pressure on the lam with the thin lams I usually just joint flat thicker & rip on the band saw and drum grind the ones I'm going to do this morning I'm doing BBH 3/8 th parallel lams I'm just jointing and using the thickness planner I have a sled with sand paper that grips good also I'm going over to the wood working shop tomorrow they sell a double back tape designed for wood turnings that is supposed to be strong hold and easy to get off I will let you know ! I only have a flat and 0.005 sleds I want to pick up or make a 0.002 !
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I made an adjustable sled out of some U channel aluminium, but it still has some flex in it >:( I may screw a rib along underneath the top section.
https://bowyersdiary.blogspot.co.uk/2017/09/improved-taper-sled-and-thicknesser.html (https://bowyersdiary.blogspot.co.uk/2017/09/improved-taper-sled-and-thicknesser.html)
I did think about incorporating a spring loaded roller into the machine, or maybe turning the top of the sled into a vacuum bed somehow... ::) ... but simple is generally best
Del
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I make a lot of hickory backed flatbows and I find that flat sawn wood works as well as quartered for both backing and belly, but you have to be much more careful when picking out the flat sawn because growth ring location matters a lot more. That being said a peice of flat sawn might only produce a couple of good bows and the rest is wast wood or in my case glued up for cutting boards and the like, but quartersawn wood you can usually use the entire board. I like quarter sawn maple and oak, white or red for belly wood.
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Thanks Green river but I'm using air dried staves in stead of boards ,Del I ran a test relating to your coment Drum sander vs thickness planer the thickness planer won hands down for tighter tolerance on thick parallel lams and quicker to ,but the lams come out like glass smooth will have to ruff up before glue that's a cool grinder you have there !
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Thickness planer
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Flat sawn
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Another view
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I had an old 6" planer I wasn't using so I took the motor and cutters out and converted it to a thickness sander with an over head drum sander. I use a piece of 1/4" thick steel u channel for the base and I made my taper sleds out of 1/4" thick plate glass glued together with spacers inbetween to set my tapers. Works very well.
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I think the narrower grinders are better because with really wide drum or cutter heads you have to find a sweet spot where it's the tightest tolerance I'm really not trying to get to crazy with the tolerance thing I'm just trying to see if I can get the bow with little tiller and right weight off the form !
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I'm confused(what else is new). I'm looking at the last two pictures of the flat sawn wood. Don't those flames mean grain run-out? Am I missing something?
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Don when you flat saw you get that cathedrale grain pattern it doesent follow a ring it will be the belly side for bamboo backed bow !
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DC, With all types of backing lams you need to look at the grain on the sides to get true picture of how straight the grain really is.
Flat sawn lams can look like they have too many steps on the back. Check the grain on the side and if the run off 1:16 or more you have viable backing strip. For practical purposes a 1/8" thick backing strip, the grain needs to run from back to belly at no point less than 2" along the length. 1:16 1/8":2".
Same again for a quarter sawn board. At first glance the edge might appear straight, have a very close look at the grain and the grain(use a loupe if necessary) may be skewed too much. Use the 1:16 ratio again.
Rift sawn is easy to see the grain lines on the edge. 1;16 ratio still applies.
For core or belly laminations you can get away with less, but always a best bet to use the straightest grain available.
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Hamish did a better job of explaining then I could but here is a couple of ruff pics ,the first is a side profile you can see how the grain is runing down the lam in betwen the chatter marks and a end view pic of the grain !
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End view
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what do you use for a grinder?
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I joint them flat on the jointer and run them threw ether the drum sander or the thickness planer the thickness planer is quicker and better tolerance for these thicker lams but for any thing under 1/4 in I have to use a sled with it and the drum sander becomes more accurate with thinner lams at least for me.
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Sounds like a good plan, is your sander as precision as your planer? Factory built? sounds like taking lighter cuts helps with the consistent thicknesses.
Don. If the ring count is up there, having flames is almost unavoidable, and if the flames direction alternates, then you are not doing so bad either.
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The drum sander is actually more precision then the planer but with longer lams you can't avoid the conveyor belt seem but with wood +- 2/1000 is about the best you can hope for .
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if the conveyer belt seam causes a divot in the sanded face, I would think you have a warranty claim
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Most conveyor feed systems have some kind of seem on the belts ,there are so called seamless belts but they usually don't come factory installed at +- 2/1000 is splitting hairs with wood , raised grain or a speck of saw dust would cause that to ,in a perfect world you would like 0.000 but it's never happened for me with wood . there are guys that claim they get tighter tolerances by grinding there conveyor belts and trueing there drum paper.