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| Acoustic Guitar Braces http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10106&t=37020 |
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| Author: | Ken C [ Thu Jul 05, 2012 7:43 pm ] |
| Post subject: | Acoustic Guitar Braces |
Who is using CNC for acoustic guitar braces and how are you holding down the stock? I have a bunch of spruce I have quartersawn and sized to my thickness needs. All are about 3/4 to 1" high and various lengths. I'd love to drop a few sticks on the table and whip out some rough shaped braces. I've been using double sided tape, but was trying to avoid using it here. I have a vacuum that I have yet to use, but I'm not sure I could even use it for bracing. Just not much stock to grab on to. Ken |
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| Author: | Tim McKnight [ Thu Jul 05, 2012 8:36 pm ] |
| Post subject: | Re: Acoustic Guitar Braces |
Hold it with Vacuum. Use 1/8" bits, shallow cuts and high feed speed. Leave stock +.020" thicker than your desired thickness then stop the cut .020" shy of cutting through. Run the braces through the thickness sander to your desired thickness. |
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| Author: | Bob Garrish [ Thu Jul 05, 2012 9:06 pm ] |
| Post subject: | Re: Acoustic Guitar Braces |
What Tim said- that's how I'd do it. |
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| Author: | Ken C [ Thu Jul 05, 2012 9:16 pm ] |
| Post subject: | Re: Acoustic Guitar Braces |
Thanks Tim and Bob. Unfortunately, I thicknessed my stock months ago prior to getting the CNC. But your approach makes sense. Ken |
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| Author: | Bob Garrish [ Fri Jul 06, 2012 12:24 pm ] |
| Post subject: | Re: Acoustic Guitar Braces |
Double stick tape it, then, just make sure you set your depth a little bit shallow and you can shave off that last thin bit with a piece of sandpaper. Since most people round over the tops of their braces a bit, you can also just do as Tim said above and use a spindle sander or the end of a belt sander to shave off the last 20 thou down to the top of the brace rather than cutting thickness off the whole thing. Alternately, you can hold it down to a piece of plastic or metal with two or three -tiny- drops of CA (and I mean tiny). Knock it off with a sharp rap of a hammer against another piece of wood in full contact with one side. |
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| Author: | Don Williams [ Fri Jul 06, 2012 12:54 pm ] |
| Post subject: | Re: Acoustic Guitar Braces |
Sometimes, there are just easier/faster ways to do things than using the cnc... |
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| Author: | Ken C [ Fri Jul 06, 2012 1:31 pm ] |
| Post subject: | Re: Acoustic Guitar Braces |
Don Williams wrote: Sometimes, there are just easier/faster ways to do things than using the cnc... Indeed Don, but right now my process isn't necessarily easy or fast. I do have a jig to put the radius on a brace, but I don't have a set of profile templates, so I have been drawing profiles on stock and cutting with my scrollsaw. I was thinking of cutting out a set of templates on the CNC when I thought why not just cut out the actual braces on the machine. I still do a fair amount of carving and shaping by hand once the braces are on the soundboard, but I'd like to have more of a consistent starting point. Ken |
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| Author: | Parser [ Sat Jul 07, 2012 11:46 am ] |
| Post subject: | Re: Acoustic Guitar Braces |
Tim McKnight wrote: Hold it with Vacuum. Use 1/8" bits, shallow cuts and high feed speed. Leave stock +.020" thicker than your desired thickness then stop the cut .020" shy of cutting through. Run the braces through the thickness sander to your desired thickness. Hey Ken - this is the other technique that I mentioned in that message the other day. Tall/thin parts can be tough to hold...this onion skin method is one way around it. The other way is to machine a whole chuck of spruce all at once and then resaw it (this is what i do...errr...used to do back when I had time!). |
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| Author: | npalen [ Sun Jul 08, 2012 9:24 pm ] |
| Post subject: | Re: Acoustic Guitar Braces |
I've had good luck holding wood parts down to aluminum or even MDF when machining. Two or three drops of medium CA on one face of the joint and accelerator on the other. I've found that NOT using accelerator creates a stronger joint that tends to cause difficulty when removing the machined part. Setting the final depth so that it leaves a tool path in the fixture makes for easier alignment of the next part going on to the fixture. I've also found that roughing the aluminum fixture with coarse sandpaper gives a sufficient bond where smooth or polished aluminum may not. Any CA left on the fixture can be removed quickly with a scraper or whatever to make ready for the next part. Several parts can be fixtured side by side using this method. Nelson |
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| Author: | Andy Birko [ Mon Jul 09, 2012 1:17 pm ] |
| Post subject: | Re: Acoustic Guitar Braces |
Parser wrote: Tim McKnight wrote: The other way is to machine a whole chuck of spruce all at once and then resaw it (this is what i do...errr...used to do back when I had time!). That's a really good idea. Shouldn't be too much trouble to do 2" thick at a time. Ken hosted a SE Michigan luthier gathering at his house a few weeks back and I suggested leaving the stock long and clamping it at the ends and to only machine the "top" and "bottom" of the braces. Cut the extra stuff off the ends with a band saw. |
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