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Bows / Re: ERC ELB belly patch

« Last post by Del the cat on Today at 03:24:58 am »

Here are a couple of examples:-
https://bowyersdiary.blogspot.com/2019/09/elm-tribulations.html
https://bowyersdiary.blogspot.com/2017/01/two-part-knot-patch.html
My advice is to take out a long scoop (at least 4") keeping it flat across the patch but curved along it's length (like flexing a steel rule). Tke as long as necessary to get a good fit, checking with the light behind it, a slight gap in the centre is ok as that will hep the ends press down when it's clamped (or rubber strapped). Make it fairly close to final size so that there is some flex to help a good fit.
If it looks like you will have to go too deep, (say there is rot or somesuch), leave the long shallow scoop and take out a shorter one at the knot and fill the problem area, once that's filled, clean your original long scoop and do the patch.
I did one on a warbow with two nasty deep chrysals which went deep, I did two deep short patches and a long one over the top of both.
https://bowyersdiary.blogspot.com/2017/05/a-warbow-repair.html
Del
PS. One bowyer was asking a mate of mine about belly patches 'cos he "couldn't get 'em to work". My mate said "I've watched Del do one and I was surprised at the amount of time he took to get a good fit, back and forth on the belt sander, checking and adjusting".
the bloke said "I havn't got time to mess about like that"

... yes, and that's why his belly patches don't work!

Bows / Re: ERC ELB belly patch

« Last post by bownarra on Today at 02:54:20 am »

The best way to fix this bow is to start another one taking the lessons learnt from this one

Saying that you can gain good experience trying belly patching on this bow.
If you try to fix it then the patch needs to be quite long out of flawless wood and glued with an epoxy like EA40. Do NOT use CA! It is really only any good for tip overlays, inlays and filling cracks (thin stuff). TB111 would be prone to joint creep in this application.

Bows / Re: auriou rasps?

« Last post by bownarra on Today at 02:44:29 am »

Quote from: stuckinthemud on August 13, 2020, 06:55:48 am

They are very lovely, but are they worrh 8 shinto rasps?

Coming from somebody who has a box full of knackered, snapped and bent shinto's and 3 Auriou rasps still in perfect condition after 5 years of solid use......yes they are worth the money

Easily

Shinto rasps are ok but they are flat both sides so no good for shaping the contures you normally find on a selfbow. They are good for lam bows. I would say a Shinto lasts me about 2 months then its done.

Bows / Re: Thickness Sander Drum?

« Last post by bownarra on Today at 02:33:31 am »

You could also contact one of the makers of drum sanders and simply buy the drum. Build your machine around a perfect drum with attachments/holders for the paper already built in.
Failing that that some ali pipe and get it turned at a machine shop.
Drum sanders are great and open up lots of possibilities but they must be accurate to really ultilise the potential.
I'd be wary of pvc pipe...drum sanders can generate a lot of heat.
No finer than 60 grit for your paper.
ideally you want your feed drum to be adjustable speed. Grinding ipe versus say walnut put quite different demands on the set up.

Bows / Re: Thickness Sander Drum?

« Last post by Badger on Today at 12:13:33 am »

I had mine about 875 rpms and I used the good quality 60 or 40 grit paper.

Bows / Re: Thickness Sander Drum?

« Last post by mmattockx on August 13, 2020, 11:13:31 pm »

Quote from: dylanholderman on August 13, 2020, 01:45:12 pm

I work in a fab shop and you would be pretty surprised at how “out” of round most of that stuff is.

+1 on that. Aluminum extrusions will be pretty close to true, but hot rolled steel sections are awful and the mill tolerances are very loose for the most part.

Quote from: willie on August 13, 2020, 08:00:46 pm

what is the planned length and diameter of the drum?

Length is 6", with the center 4" used as working area. Diameter was originally planned at 5", but I have a piece of scrap 4" PVC which is a touch under 4-1/2"OD, so that may be the winner.

Since we are discussing this, what drum RPM do people use on their sanders? What grit paper do you use?

Mark