• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Warped body!?

#21
Meatrus said:
Sanding would be a pain, but it would be possible with 60 grit or lower. I offered it as a no skill required option :smug:. A scraper would be much quicker, if you feel you can use one well enough.

Whatever happens, good luck!
Click to expand...

Ah yes, true, true :smug:. Let's see what happens...

I start to think more and more a home made drum sander would be a very useful tool. Especially when I start with the next level, jazz box or acoustic guitars.. :hiding:
 
#22
Starting a project off with these issues is just going to make more work throughout the rest of the project since you are going to have to compensate for the warp. You might consider redoing the whole thing and doing it right - plane off the maple, reflatten the core and glue top and back veneers. It is going to take some time but it will come out perfect. Chalk it up to a learning experience. The sign of a skilled craftsman is the ability to correct their mistakes IMHO
 
#23
powerbass said:
Starting a project off with these issues is just going to make more work throughout the rest of the project since you are going to have to compensate for the warp. You might consider redoing the whole thing and doing it right - plane off the maple, reflatten the core and glue top and back veneers. It is going to take some time but it will come out perfect. Chalk it up to a learning experience. The sign of a skilled craftsman is the ability to correct their mistakes IMHO
Click to expand...

Wouldn't that be too rigorous for something you almost cannot see by eye and probably or maybe could even correct itself along the way?

Due to the lack of professional stationary machinery I cannot plane off the maple and flatten the core. Next to that, the top costed 80 dollar and it's a very, very nice piece of flamed maple. Not something I would just plane off even if I could. The core set me back 145 and all together with the veneer this body costs about 240 dollar. I think, considering this, correcting it will be more efficient (if it doesn't correct itself).

Next to that, I do not think that something really went wrong, it's just a minor distortion that I want to:
  • understand
  • check if I should care fixing
  • learn from it
 
#27
What Pilotjones said, just wait for a time and see if the wood moves. If it is still not stable than this may be an (extreme) option to stabilize the body. Cut the body in 3 pieces. Put two laminates through length of the body. Correct the three pieces sides so that the whole is flat again.
images?q=tbn:ANd9GcSPu3lAkocgJ0CU42nKxWyoFL72AbDyNe3cUwQJHV5D75SnfHKO.jpg
 
#29
I checked my bridge on the center of the body and there's no visible or measurable warp underneath it, so the bridge seems to sit level. Since the bridge is wider than the neck, I think I'm safe. Although it's a pity that it also bent lateral...

I stick with monitoring the deviation and hoping it'll stay stable or even correct itself somewhat when I work on the neck.

Case closed ;)
 
#32
I finally understand what happened! Or at least, I think I did!

Every time I went in the shop I checked the state of my body and found that it didn't move anymore since I discovered the bending. It's still max. 1,2 mm while the center (where the bridge goes) is relatively flat. And every time I was pondering about the reason behind this. I need to know, because I want to learn and I didn't understand: why did it bend upwards while I introduced the moisture (glue) in the top? If anything, the top should've expanded, causing it to warp backwards...

And today, I suddenly got an idea!

On Friday, I glued the top and the veneer together. I let it dry and left it in the clamps for about 24 hours. Everything was looking good. On Saturday, I glued this composed or assembled top to the core. I also left that in clamps for 24 hours. When I got it out of the clamps, it still was nice and flat. Even when I did the roundovers next week. But after a month, I discovered it bent. And after that, it became stable again, for several months now.

So what happened? The problem was I did this in two stages:

  • I first glued the top. That's pretty thin. It expanded because of the introduced moisture content, using Titebond.
  • Then I glued that to the body. The body also got some moisture to cope with, but since it's a lot thicker, it didn't move as much.
  • Titebond sets quickly. After an hour, the parts became joined inextricably.
  • But the top did have a day before the glueing to expand all by itself... so now, it starts to shrink... after it's fixed in place.
  • The body didn't expand as much as the top did, so when the whole assembly starts to dry, the top is shrinking more than the body et voila: it's going to cup.

If I'd glued all layers together at once, the top got fixed in place before it got time to expand so much (Titebond sets in 30 minutes). If it would've expanded, the body would've held this motion back somewhat and, the body would've bend backwards to let the top expand and if the top started to shrink again when drying, the whole body would became flat again.

Long story, because it's hard to explain (I always need more words than I want to), but, what do you think? Could this be it? Does it make sense?

:eyebrow:
 
#37
A moisture meter, I have a few, but here's what my cheapest one looks like (the small metal probes get pushed into the wood, for a reading. One key thing to remember is that the reading is more accurate somewhere in the center of the piece and not the ends.):

41bOFkksKAL._SL500_AA300_.jpg



It is very important to check your moisture content, before working on the wood. It's another important factor to building.

octaedro7 said:
What's the usual method for measuring moisture content?
Click to expand...
 
#40
The story continues.. I can't get it out of my head.. probably, a lot of builders around here wouldn't worry about the slight cup, but I just don't like it and I keep measuring the movement each time I enter the shop.

Right now, it's freezing like crazy here in Holland, been below zero for weeks, with temperatures below -20 C. So, with a heated workshop and no humidity control, the humidity got as low as 32% for over a week already. This probably dried the body even more and the cup went from 1.2mm to 1.5mm..

So I decided to take the plunge and I've done the following: I wiped the top with a wet rag, not soaking it, but just so that after wiping it there's no excess moisture left. Then I clamped the body upside down between a table and an MDF board (together over 2 inches thick) and an MDF board and my prototype MDF body (almost 2 1/2" together). I used 6 massive clamps and with the heavy sandwich it's in, I easily got it pressed flat.

Now, we wait...

I hope the top will expand. Dry. And the pressure will keep the body flat while drying.

I know it's a long shot. But in theory it's possible and.. doing nothing wasn't an option really. I would regret that later on. Worst thing that can happen is that it doesn't work and that, after drying, it goes back to being cupped. But at least, I have tried... I guess.

Not sure how long it should stay in this position, but I glued the body exactly 4 months ago. The first month it cupped to 0.8mm, the second month to 1.16mm, the third month to 1.2mm and the last week to 1.5mm.. it doesn't get any dryer than this (and yes I know, I should buy a real moisture meter for my wood very soon), so I feel it got more or less stable after two months. Also, the glue introduced way more moisture than my wetting did, so I reckon one month now should be enough.

:eyebrow:
 

Latest posts

Top Bottom
Back