Official Luthiers Forum!

two questions for you seasoned veterans.

1. I've searched long and hard through the archives, but haven't found a satisfactory answer to this one:  In reading about The Stew Mac bearing set, I believe the bearings actually cut .012" deeper than marked depth to allow for swelling of the binding and glue when all is said and done.  So if one takes the swelling into consideration with the rollers, should .012" also be factored in when setting the vertical depth of the router cut? 
Knowing that most hobbyists like myself only build a few guitars a year, I get to the binding part VERY rarely.  I think I've been lucky each time I've done the routing, and this time I don't want to chalk it up to luck so I bought the bearing set and bit, and build a Williams jig.  I should be able to use it this weekend, but I'm a little scared to until I can be reassured by my 2X4 test cuts and this little piece of info.

2.  Second question relates to a SEVERELY warped EIR jointed back (for a separate guitar) that has been thicknessed to just over 2mm.  I've had the bugger stickered and pressed between two boards and it does not seem to be getting any better.
The room it is stored in has been climate controlled at 48% RH so  one would think it should be acclimated enough, after three weeks to flatten out.  However it shows no signs of taming down.  Its matching sides are just fine and show no troubles.
Manipulating it freely could be likened to playing a double jointed Australian wobble board.

If patience is the key here, I can live with that (climate controlled or not, MN weather has been brutal lately and it was extremely humid when I planed it down a month ago)  But if there are other things I could do to help the process, please suggest away.

Thanks in advance for your input,

Dave

Dave, Try "stickering" the wood instead of pressing it between boards. Stickers are small thin pieces of wood that allow the board to be stacked with air circulation around it. They are placed perpendicular to the board. Added weight on top of the stickers should help. If not, you can always try dampening the boards and allow them to dry again. at 2mm, you should be able to straighten the wood out quite easily.

I dont use the stewmac router jig or cutters.

I can tell you this much: It is better to have your bindings a little bit proud of the sides and top than it is to have them too far in. It is easy enough to sand or scrape a little off after drying than it is to add some on.

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Reguards,

Ken H

Dave, the second EIR backset is glued up right?
And it is warped, right? And won't lay out flat, correct?

It sounds like the humidity has gotten to it, causing a warp in the board. You could just go ahead and glue up the braces, which would rigidize the back and most likely take care of the problem. Normally a joined backset lies flat. But.... I'd recommend a different approach.

If you have enough wood to spare, why not cut the backset apart and rejoin the back? That would allow you to relieve the stress no doubt the backset is under.

I'd want the wood stable, as to RH. Rejoin, then get it braced and glued to the rimset. If you aren't going to join to the rimset, just leave the rejoin process alone until you are ready, just cut it apart and sticker with added weight atop.

Good luck, I bet you can solve this little problem with good ol' common sense.

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http://www.dickeyguitars.com

As far as the Stewmac bearing for their Dremel router base; The only place I find it to be worth a fkying flip is on a peghead because of the flat bottom of the base and the low profile of the bearing. Also the bearing in not very good and a Dremel is way under powered for the task and tends to have too much bearing runout.

But to answer your height or channel depth question. I rout to just .005 deeper than the binding and purfling stack the binding will swell some in height but I don't seem to get .012" worth. Plus because it is on the extreme edges of the body when I scrape to level with top or back I still end up with consistent height bindings so why complicate the issue.

As for the wood warp. I sticker in most cases for at lest a month and prefer 3 to 6 months before I use the wood.

thanks for the input guys.

I sent the message last night, hit send, and then fretted about it for a while as I climbed into bed.  About the time my head hit the pillow, it hit me that the stress within the warpage is probably due to the fact that it is joined.  So I figure I will saw it apart and rejoin it.
Hopefully that will take care of it.

I'll vertically set the bearings dead on and scrape what little there is away if there is anything to scrape.

Dave

Can one rejoin a thinned top?

What IS the reason we join then thin and not the other way around?

[QUOTE=livemo1]Can one rejoin a thinned top?

What IS the reason we join then thin and not the other way around?

[/QUOTE]

I do it all the time. I have a drum sander and it gives pretty uniform thicknesses to join up though. If you are doing it by hand, I could see where this might cause a "lumpy" joint and would be better if you joined them first.

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Reguards,

Ken H

Hi Dave,

Fellow Minnesotan and experienced luthier Grant Goltz would tell you to get out a clothes iron, set it to "cotton", (hot) and quickly iron the back flat. When you have it as close to flat as you can get it, lean it vertically to allow the heat to leave both sides at once. Don't overdo the ironing, and the glue joint will be OK.

If the final shape of the jointed and sanded back is mildly a potato chip shape (a couple of wide waves), then the braces should be able to hold it to the desired radius.

After it cools, take a radiused brace piece and hold it in place with just your fingers. If mild fingertip pressure makes it conform pretty well to the arch of the radius, then glue should be able to hold it to the braces without a lot of built-in tension.

If you overdo the ironing, the glue joint may come apart, and then you can freely iron the halves, rejoint, and reglue. You won't lose anything by trying this method. And, if you do, please report back how it went.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

If you try ironing, please take before and after photos, and post them here (whether you are satisfied with the results or not), so we can see.

Thanks!

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

I had this in a top that I lightly shellaced (according to Kinkead) It gave me a "bridge warp" it went perfect convex with the top poping out, about 2 inches. This is now my test top for other reasons, Im not sure sawing it apart will do the trick, you may get another warp when you put it back together.

 

I had warp in my mahogany back when it came in peices. I water/ironed and put lots of weight on top between newspaper to absorb the water, and it tured out ok, and has not warped at 1.0 thickness

 

Basicly if you wet the top of the wood it will warp like a bridge, convex. Be careful if you wet, do a little at a time.

 

 

I have used the cloths iron for years. It works. It takes about 30 minutes or so. Once you have it flat ,and don't use any steam just let the iron heat the wood and you will see the steam vacate at the ends. Once the wood is supple I usually glued in the braces . One thing about this technique is that none of the backs and tops I glued this way ever cracked
blues creek