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Building Tips and technical articles. => Building techniques => Topic started by: louie klein on May 12, 2011, 01:29:49 PM
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I've been look'in and look'in but can't find a good way to put round holes in ribs without grabing, ripping and cracking the wood. I heard a while back something about copper tubing as a punch, any help? Thanks---LOUIE ??? D>K H^^
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How big a hole are you looking for ?
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A good sharp hole saw.
Template with hole and a good sharp X-Acto knife, wielded carefully.
A good sharp Forstner bit.
A good sharp "brad point" bit (which, in a pinch, you can grind from music wire).
Note the common factor. Note, too, that a good sharp twist drill will leave you with a mangled mess -- twist drills aren't made for drilling wood, and they're especially bad with balsa.
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Louie,
Depending on the size of hole you want, you CAN make a punch of brass not copper tubing. Brass is harder than copper...
Way it works - shave the inside of the tube end to form a cutting edge while the outside remains stock. An old #11 blade works just fine...
This is good, depending on the sizes of brass tubing you have, or are willing to buy for this use. Say the largest you find practical is about 5/16" diameter... You use such a punch by pressing and rotating the cutting edge, with the stock to be 'punched' backed up by a cutting mat or a piece of carboard like the back of a lined pad.
If you press into the balsa straight enough, you'll get a very neat hole that size with no splitting or tearing. Of course, the 'plug' you punched out has to be popped out of the punch each time. No problem; a piece of, say, 1/8 music wire works well.
You could use smaller punched holes like this for the corners of a larger area cut-out. Figure where you want the shape, cut the corners, and slice out the area between them witha (sharp) #11 blade. Again, it helps to do this over a backing, and to guide the X-Acto on a metal straight edge.
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It's the "old brass tubing sharpened in the drill press" technique for you Mr. Klein. ;D
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I know there are guys who get it to work, but I've never had any luck with the brass tube method.
Depending on the size of the hole needed, I'll drill a hole big enough to accept my drum sander on the Dremel. They have a large and a small drum sander available. Then, with a steady hand, I'll go back and finish opening it up to the desired size with the drum sander.
If it's a BIG hole, start again by drilling a hole big enough for your scroll saw blade to pass through. Then finish the hole with your scroll saw.
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I do the brass tube method. I use an X-Acto knife and the drill press.
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Brass tube is the best way for cutting holes in ribs. Just have to sharpen it pretty often. Like when the wood starts tearing instead of cutting. H^^
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The brass tube method works fine, but what you must do is use an old piece of block balsa for backing, say 3x3 and push on the END GRAIN, then there is no tendency for the rib or whatever to crush. Rotate the tube as you push.
Cheers
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I put little nicks in the sharp end of the tube, with an #11 blade, to make it sort of saw-like.
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I do that too, with a small triangular section file.
Cheers
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With brass tubing, sharpened on the inside edge with a X-Acto #11, I also made small "nicks" to help cutting. Then, I had to cut holes in 1/8" ply. So far, so good (on the drill press). But the ply "plugs" were hard to remove from the tubing. So I Dremeled a 1/2" long slot in the side of the tubing. Now, a piece of piano wire will "flick" out the plug imbedded inside the tubing. Not necessary with balsa, but works well on ply.
Floyd
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I've been look'in and look'in but can't find a good way to put round holes in ribs without grabing, ripping and cracking the wood. I heard a while back something about copper tubing as a punch, any help? Thanks---LOUIE ??? D>K H^^
That was brass tubing, as many here have noted. Recently, however, I found some relatively thin-wall stainless tubing in the K&S display at the local hobby shop, and while it was a lot harder to get an edge on it, it's far better than the brass. The problem with brass is that it is so soft that it loses the edge quickly. With the stainless tubing, grin with a Dremel grinding point while spinning it in a drill press, make the edge angle extremely shallow, and it works very well.
I use it over one of those green cutting mats, that is plenty good enough to allow the tubing to cut cleanly.
BTW, Copper would work much better than brass because you can work-harden it. The reason brass was invented was to prevent that - it stays soft and malleable even if you do work it. The problem is finding copper in the many different sizes you might need.
Brett
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I built a Peacemaker a while ago and - um - forgot to put the leadout holes in ... I know I know !
A piece of sharpened aluminium tube worked just fine.
Annette
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Thanks for all your help guys! I'll go with trying the tubing, I think this is the old tried and true method I tried to remember. Thanks again!---LOUIE H^^ H^^ D>K
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If your talking about hole is 1 sheet of balsa then the tubing is the way to go....Larger holes could be opened with any small drill and sanded larger....
If your talking about many holes like in a set of ribs...then you can drill it if you an apply pressure on both sides.
as in sandwiched between plywood templates.
What you drilly determines weather you can drill or need to punch it..
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For holes a touch over 1/2" I use an old golf shaft with the grip still on it. A slot cut in the side to punch out the plugs. Use a Dremel grinding tip to sharpen the inside of the tubing. It is very thin walled and will stay sharp for quite a while. I have a piece of thin wall steel tube about 4" long, I found somewhere, that cuts a hole close to 1" in balsa. Same method to sharpen.
I have found that all the tubing "cuts" best if you twist as you punch, much like drilling.
Big Bear
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Various taperd bits are available from Dremel, fordom etc. that are ideal for drilling holes in ribs. You can buy them at wood carving shops, Home Depot etc. Just chuck one in a drill press for an easy job.
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Ty, That's a great idea. Thanks for the pic's!---LOUIE y1 y1 H^^
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It will depend on the wood but I have successfully used a hand held paper punch. If the wood is hard and brittle (some that you probably wouldnt use anyway) it may split.
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Find a telescopic old radio or walkie talkie antenna. Dissassemble and sharpen as above. You get several diameters this way. Sturdy and very thin wall.