Thickness sanding?

[Prarie Bowyer]

Hey all.

So may brain has been cooking on making core laminations consistantly.  My Flat bows use a uniform thickness core then the belly is tapered.  However I'd like to start doing more bows with bamboo on the back and the belly.  For this I think I need a way to accurately taper my core laminations.  As much as I hate dust I don't hink hand planes and scrapers are very efficient here.  They could be with a shooting board and perfect grain on all wood. . .  which does not exist.

So I'm not understanding how a drum sander can give you consistant tapers with out allot of creative sanding and such.  My inclination is to build a track with a pivoting bottom say 48" long, and a sled for the hand held belt sander. Then I "think" I can do that accurately.  But then if the wood is warped I'm screwed.  I built a flat thicknessing jig from my router but it needed allot of scraper cleanup.  Not so efficient and if the wood was warped I'd get thin spots that needed clean up despite my clever "hold downs" to push stuff striaght.

So how are tapers sanded on a drum sander?  Or are they cut on a table saw then the tool marks sanded out.  I haven't got a table saw but I have a big band saw.  I've gotten some good tapers by hand simply by bandsawing, then planeing out the tool marks and hand sanding Scraping to even up.

I'm looking for a low cost way to get mostly consistent results.

[mikekeswick]

If you are using a drum sander all you have to do is cut out a tapered (the same taper as you want for the core lam) sled that your (to be tapered) lam sits on. Then run it through and the high end gets sanded first down to the angle of the sled. Make a lip on the end of the sled that holds your lam, it's also a good idea to put a non slip surface on the sled to minimise the chances of it moving whilst going through the sander. It's a bit of a pain making the sled accurate in the first place but once done it makes the job so easy! Perfect glue lines, no thin spots and all you have to do is stand there and watch and the best bit is it's repeatable! Obviously with this method you have to splice the two lams together but thats easy enough anyway.

[Prarie Bowyer]

I'm on the verge of buying an upright pivoting belt sander.  I've seen jigs that will fit these as well.  Then I started thinking about this and wondered if I wouldn't get more mileage out of long track/sled and hand held sander.  I think I'm gong to try to build it but my concern now is that If my wood has warps in it then I could still get thin spots. . .  or not? 

I'd rather not need to buy all the variuos tapers I may use when I could make an adjustable track.  I'm sure there is something I'm not thinking of.

[mikekeswick]

You don't need to buy the sleds just make them on your bandsaw. I like your idea of making it adjustable. You need to start with a perfect parallel lam to insure no thin spots, that why a proper drum sander is excellent for this sort of thing. If you do some searching you can find plans to make a drum sander - yes it's a bit of work but if well made it will serve you very well and opens up lots of possibilites.

[Del the cat]

Not my area of endeavour (yet ), but a V interesting thread.
Is double sided tape a good idea to hold your lam to the sled?
Del

[Prarie Bowyer]

Good Question Dell.  I've been thinking of that. 

what I'm leaning towards is a a shallow track with rails on the sides.  The bottom Pivots at one end witha small extension for clamping.  The thread is on the other end which will adjust. that way I can do a lnog lamination in 2 parts if need be.  Just turn it around and reclamp it.  Or I could do two shorties with a splice.

Using hand planes the fore sole of the plane presses thin warped wood flat so thin spots aren't as likley unless you make too many strokes in pne place.  Then again so may the weight of the sander.  I have an offer to borrow either type of belt sander so that will give me a chance to get a sense what will work best.  Though my sled will need to be custom fit to the belt sander.  Possibly I could attach some kine of hold down guide to the sled.  If done right a 35-40 grit belt will clean up a band sawn lamination in 1-3 passes and simply stop sanding when it's finished.

NOT looking foreward to the dust mess.

Tape.  POssibly but for feather tapers I'd be afraid of breaking it on removal.  My thinking is to clamp it and turn the sled so that the rotationary force is pulling on the clamped end.

[PatM]

Hee's a link. Just need to build the tapered part.
 http://woodgears.ca/sander/thickness.html

[Prarie Bowyer]

That is a drum sander.  To use that I'll need to make the opposite sides of my taper templates as I understand.

[mikekeswick]

Hee's a link. Just need to build the tapered part.
 http://woodgears.ca/sander/thickness.html

Thats a great link. I know it's a fair bit of hassle to make one but once you've got it...These machines open up lots and lots of possibilities.
Your ideas will work but after a few bows you might start wishing you'd made a drum sander.....

[Badger]

   I will often use tape to make sleds, I just stagger each layer of tape depending on the thickness and desired taper, once you layer your tape just place a flat pice over it and run it through a planer and you have your sled.

[Prarie Bowyer]

Badger,  I didn't think of that.  wouldn't the layers create "steps" in the final?

I guess I'll need to scan and load my idea to Photobucket than link to it here.  It's all such a pain for a concept sketch.

[Prarie Bowyer]

Well for the cost of a set of 50grt sanding belts I made a drum sander attachment for my lathe . . . complete with knuckle knockers. .  It works fairly well.  However now to sand tapers and accurate flats I need to make an adjustable bed that will fit right under it.  And I'll need to make the tapers that attache to my laminations.

I was looking at my forms which I built for using Bamboo on the backs of R/D bows and wood (Osage or hickory) on the bellies and realized that if I wanted to make bamboo bellies also then my form is "upside down".  I was just about to pull some wood out of the rafter and remake the forms when I realized I could do a riser that fits inside the bow between the layers.

I'm so smart I scare me sometimes.

[crooketarrow]

  NOT VERY PRIMITIVE

[Prarie Bowyer]

Yea I like the wood work and archery but I like exploring the making and designing bows mor than anything.  I feel like Mel Gibson in the Patriot with his rocking chairs.

Hey, I shoot an all wood bow with wood arrows and trade points at animals.  Maybe one day I'll hack the stave out of a tree but I prefer to get them made.

[Prarie Bowyer]

After looking at several models of belt sander I figure the work to make a sled and track system is not worth it.  They are all so ergonomic everywhere and I'd need it to be adjustable.

I've started making a mini drum sander for my lathe.  Then I'll get cheap tapered laminations and set them aside as templates.  I'd like to show pics of it but Photo bucket won't let me in to add photos!