I know everyone here uses or grinds 36" tapers. Myself included. BUT after building a repo old Bear bow and after closely inspecting many of the older Bear bows I think they used a one piece 72" lam ground to taper both ways! I've got my ideas of how to do it but I wonder if anyone else has done it?
The lams I use on the back of my bows are all one piece and tapered from each end. I have a 3' sled that has interchangable tapers, grind one end then reverse the lam, easy to do. I also stop the taper 2" from the fades to move the bend farther out the limb.
I did not do it to now but I don`t think it`s a big thing- as long as you have enough space and support for the workpiece around your thicknesser...
The tri lam I just made has a tapered one piece cedar core lam.
I do this on all my bows and I really think it is the way to go given no splice lines (and it is faster/easier. Simply make a 72" sled using two evenly tapered lams and you will be in business.
Well I figured you experts had the answers. My problem is I use a Delta drum sander and I always get "snipe" on the ends. So I plan for it and adjust the length planning on cutting out the snipe. SO if I was doing a single lam double taper I'm thinking I'd be able to leave the snipe in the center take my accurate measurements of what I need 3" past center. The sniped center section would be in the non working part of my riser. Thoughts or ideas? Thanks
Make the sled like Brad said- 72" - snipe will always be on the thin ends at bow tips then too....
Well I've always had problems starting a thin ended lam into my drum sander. Seems it would bow up and catch so to speak and do weird things. Even broke and ruined a few. So doing 36" lams after after a certain point I flip and always start the thicker end in first.
OK , I have always wanted to do this but I am having a "senior" moment.Could anyone post a drawing of what this double taper sled would look like? Bob
Hey coop don't start without me.LOL see ya soon my friend
Yeah pics please.
Just take a parallel(run it thru both ways to get nice and parallel) and spot a couple of the desired tapers on it with the thin end to center with CA and clamp where the glue spots are.
Sorry , no pics....
(http://i2.photobucket.com/albums/y17/LCooper/IMGP0228_zps51782768.jpg)
Excuse the drawing not pretty but couldn't sleep before going to work so thought I'd throw this up here.
Drawing 1 is a one piece 72" sled. Problem I see is laying a parrell lam ontop to begin grinding it would have to "bow" down as it's being ground. But my bigger problem with this is on the bows I make I use two .002 tapers and the thin ends get really thin on the ends then so as in drawing 3 when I feed into the drum sander bad things happen. So back to drawing 3 after I get the lam grining the entire length I switch sled ends and feed in from thick end. Which if I had time I'd added a drawing 4 with the sled reveresed so getting down to final taper I feed my sled in opposite of shown in drawing 3 so thin lam end is last to be ground.
Other option as some have said is Drawing 2.
Well I couldn't sleep and got up early before work but not early enough! I would have liked to explained more but curious of what you folks think about it.
I have done it like drawing 2, but # 1 is quicker for me.
do you have an infeed/outfeed table on your sander? Might help with snipin.
Also , I always adjust my in and out pressure rollers according to book, that helps with snipe also...
If you go with # 3 and don't use the whole lam, just make a mark on edge of lam past the snipe and measure there?
Thanks guys, goin out to the shop to xperiment.No 1 looks good if the thin end of the lam doesn't blow up. Bob
I don't have a thickness,sander. I do have a cheap thickness planer.
On the planer I set the thickness and it goes through taking wood off on the thicker areas and not touching the thin area.
With a thickness sander does it operate differently? Is it some how spring loaded where it follows the taper?
Mac I think the thickness taper is created by the sled which is cut at at angle compared to being a flat 90 degrees. It being say 1/8th from the belt on one end and 1/16th from the belt on the other end.
I wouldn't recommend using a thickness planer for making tapers. It will more than likely catch the thin end and destroy the lam. The newer ones that have a spiral cutter head may not be as bad as the ones with straight blades, but I still wouldn't take the chance.
Tapers can be done on a jointer, if you don't have a thickness sander. Mark the center of the lam, then make a mark at 1/3 and 2/3 of the distance from the end to the center. Do the same on the other side of the center mark.
If your lam is 66" long, then you will have a mark every 11". Then you plane from the end to the first mark, turn the lam around and plane the other end to the first mark. Now start again from each end and plane to the second mark. Lastly, plane the whole lam from end to end and you will have a double taper.
The safest way to do this is to start with a thick piece of wood. Once the tapers are cut, you can cut the tapered side off at the thickness that you want using the tablesaw, or better yet, the bandsaw.
One thing to remember. Be very careful when doing this kind of planing. Use a pair of push pads to control the wood and keep your fingers away from the cutters!
Dave.
no, the sander is not spring loaded, the table height is adjusted in relation to the sanding roller- just like a planer would work.
i have seen some very nice lam grinders made using a bench top belt sander, and even with a sanding drum chucked into a press drill.
and if it wre me, i.d get some tapering sleds from Kenny- phone him, he is the most helpful guy.
get two sleds the same, and glue them to a solid backbone of wood, with the thin ends butting against each other- and you should be good to go.
i think thats what kenny suggested too.
it would be the simplest, most ACCURATE, cost effective method.
I think I'll wait till I can afford a thickness sander.
Thanks for the info. I think I got the picture.
I'd like to do,something,like that,for my BBI bows.
Certainly will be getting the tapers from Kenny when it's time.
Probably stop by his place later this spring when heading to Iowa to visit.
Mac do me a favor. When ya meet Kenny, thump him for me:)
OK, the next question is"WHY HAVEN'T I BEEN DOING THIS FOR THE LAST 10 YEARS!!!!!!!.Took a piece of 3/4' MDF 2" wide x 72" and then made a pair of 2" wide .002 tapers and fixed them to the mdf with carpet tape with the thin ends in the middle. Then I put a strip of 100 grit sandpaper on top of the tapers with carpet tape.The sander roller pressing on the lam against the sandpaper keeps the lam from squirting out while grinding.Quick, easy and makes very accurate lams. I am using A-boo stair risers to cut the 72" lam blanks. :knothead: Bob
Sounds perfect Bob!! :thumbsup:
Sounds great Canadabowyer. Curious how thin do your lams end up being on the thin ends?
Roy, I've met Kenny. That ole farm boy is too tough to thump.
I mind my manners around him.
LC, the thinnest I have done so far is .038. Thats a .110 x .002 lam. I believe I could go a bit thinner before having problems. Thats using a Performax 10-20 with 36 grit sandpaper.A-boo grinds easy, it might not be as easy with hard wood but I don't have any 72" hardwood blanks to try right now. Bob
Thanks Canadabowyer. Most of my bow weights require a 36" lam .002 taper at the thick end starting at .096 or .094 with the thin end being .034 or .032. I know early on that I had a few blow ups feeding the thin end at those thicknese's so I end up flipping the sled and feeding the thicker in first. I suppose since I don't actually use a 36" limb I could cut down the 72" sled to a more usuable length. My other problem is I don't have any wood on hand over 40" since I never thought I'd be grinding a full length lam! Oh well live and learn. Thanks
Bob I feed the thin end in carefully and hold the lam down close to the rollers so it doesn't buckle. then reach around and pinch the lam when it is completely through to the sled so it does not slip and hold it pinched until the piece is run . You can grind incredibly thin lams this way without breaking them. Until they get thin enouugh to wrap around the drum. then you lost it. LOl;. You can also tape the lam to the sled with two way tape if you wish It will be a couple thousands thinner but will work.
God bless you, Steve
Thanks Steve, I think the tape idea would work fine. :thumbsup: Bob