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reusing StewMac magnets...?
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10137&t=50731		 Page 1 of 1
Author:  flemsmith [ Mon Jun 11, 2018 11:36 am ]
Post subject:  reusing StewMac magnets...?
Just ordered a few more 1/2" magnets for inside cleat attachment brackets. Last one I made, I attached the magnets to the softwood bracket using JB weld, so it's a fairly permanent little bracket. Since each inside bracket (what's the luthier term?) tends to be one time use, I was wondering how experienced repair techs mount the magnets? Ideally, I'd like to be able to use for a crack repair, then be able to remove the magnets and use in a different custom bracket when I need to make one. Or, at $5 each, (times 2 for each application), am I just being cheap? I like to call it thrifty.

roy
Author:  Chris Pile [ Mon Jun 11, 2018 2:07 pm ]
Post subject:  Re: reusing StewMac magnets...?
I'm not sure I get the full meaning of your post, but I think you mean "jig, fixture, or tool" when referring to bracket.... Am I right?
Author:  dpetrzelka [ Mon Jun 11, 2018 3:24 pm ]
Post subject:  Re: reusing StewMac magnets...?
I use double stick tape to mount magnets to different cauls—if that what you mean.

Sometimes carpet tape, thin double-stick foam tape, sometimes just regular office supply double-stick.
For crack repair with would magnets sometimes I drill holes in the back of the plastic caul leaving a think layer of the material between the magnet and the instrument. They just drop out when I'm done.
Author:  flemsmith [ Mon Jun 11, 2018 3:28 pm ]
Post subject:  Re: reusing StewMac magnets...?
yes, it's the piece of softwood with relief cut in it to miss the braces that I use on the inside located by the two magnets on the outside of the top to get cleats into the right position/direction. I use two 1/2" magnets embedded in the "fixture" to mate with the two on the top of the guitar so the cleat goes where I want it to go. Stewac sells an arrangement that uses plexiglass fixtures inside, I'm just cc'g their idea with some softwood. I already give StewMac enough of my dinero. Seldom do the fixtures/jigs I've made in the past work just right for the next cleat I need to attach to the next guitar.

Cauls, so that's the word! Thanks. roy
Author:  flemsmith [ Mon Jun 11, 2018 3:35 pm ]
Post subject:  Re: reusing StewMac magnets...?
So, If I understand, I'd still want to drill 1/2" holes and double stick the magnets flush with the caul clamping surface so the cleat gets good pressure while it dries. And I suspect the technique must be to get the inside caul in roughly the right position first, then attach the top magnets where you've previously measured. Otherwise the top magnets are strong enough to pull the bottom ones out of the caul, right? But seems like I'd end up moving the cleat around a bit that way, smearing the glue....?
Author:  dpetrzelka [ Mon Jun 11, 2018 6:21 pm ]
Post subject:  Re: reusing StewMac magnets...?
I'll try to post some photos of my approach
Author:  flemsmith [ Tue Jun 12, 2018 1:17 pm ]
Post subject:  Re: reusing StewMac magnets...?
I really appreciate your willingness to help out a beginner. Just so it's clear, I think the only thing I don't understand is how come the outside magnets aren't strong enough to pull the double sticky taped inside magnets out of their 'alignment nest'. Those magnets seem awfully strong to me. If that's not a concern, then I do understand what you've described, and I'll give it a try when my next order of inside (1/2") magnets arrive. Thanks, roy
Author:  SteveSmith [ Tue Jun 12, 2018 3:16 pm ]
Post subject:  Re: reusing StewMac magnets...?
Here's one I did yesterday. Crappy bridge design on a 12 string, everything is plywood and not the good stuff. Needed a brace behind the bridge plate. I used double stick to put a 1/2" magnet under the brace. The other magnet was on top to help locate the brace when I put it in and to hold it in place while I got the clamps on. Makes it easier to move fast when using HHG.

Note the brace outlines on the tape. I use the magnets to locate the edges of braces and such in the box then layout the position on the tape. Those are the marks I used to shape the brace.

FYI the spruce patches are not poorly fitted, they just haven't been levelled yet :)ImageImage
Author:  flemsmith [ Tue Jun 12, 2018 3:54 pm ]
Post subject:  Re: reusing StewMac magnets...?
Very nice way to duplicate the geometry from the inside to the outside. I need to try that. Although not exactly what I was originally asking about, as you were able to use a single magnet on the backside of the patch you were glueing. Let's see if I can show a pix of the kind of caul I'm talking about. roy
Author:  flemsmith [ Tue Jun 12, 2018 4:10 pm ]
Post subject:  Re: reusing StewMac magnets...?
OK, here's the question I'm trying to ask...
https://photos.smugmug.com/Guitars/i-ZB ... 5949-M.jpg

Small caul (is that the right term) was used for a simple cleat attachment, centered between the magnets. Now I need to do a more complicated one for which I ordered new magnets. I'd like to duplicate the first approach and then reclaim the magnets. Is double sided tape strong enough to hold the magnets in place when I have the cleat(s)ready to glue? I'm visualizing one or both of the magnets getting yanked out of the caul before I get the whole assy in the right place, making a mess of the cleat attachment.
Oops, sorry, I thought I knew how to post a pix, at least the link works (for me).
roy
Author:  SteveSmith [ Tue Jun 12, 2018 4:50 pm ]
Post subject:  Re: reusing StewMac magnets...?
I see what you mean. The double stick tape isn't all that strong. I don't think it would work well for the application in the photos. For that I would be tempted to try a short (3/8"?) #4 or #6 (whatever fits) brass flat head screw. Or you can use a steel screw if you want a bit more power from the magnet. Then it would be easy to reclaim the magnet.

The magnets are not real expensive though.
http://www.magnet4less.com/product_info.php?cPath=1_128&products_id=607&osCsid=gurbnn1umpvqlgr60pvf1lqrp4
Author:  flemsmith [ Tue Jun 12, 2018 5:34 pm ]
Post subject:  Re: reusing StewMac magnets...?
well, duh...! Why didn't I think of that? Glad I asked, and only slightly embarrassed that I never even considered using a screw to attach. well, mebbe a little more than slightly. Still, glad I asked, and thanks!

roy
Author:  SteveSmith [ Tue Jun 12, 2018 5:54 pm ]
Post subject:  Re: reusing StewMac magnets...?
flemsmith wrote:
well, duh...! Why didn't I think of that? Glad I asked, and only slightly embarrassed that I never even considered using a screw to attach. well, mebbe a little more than slightly. Still, glad I asked, and thanks!

roy


That's why we hang out at the OLF. I've had more than a few duh moments myself here.
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