Warped Scales

S

SS369

Joined
Nov 29, 2015
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224
Good day all.

Needing some input on the why it happens and potential fixes.

I have well stabilized scales of various woods, burls, some dyed, some
not.
I flatten them on a flat plate, till I cannot see between them, using 60
grit paper finishing with figure eight motions.

I did not use powered sanding so no heat was introduced.

Against each other they were flat and almost "Stick" together.

I then glue G10 liners with a thin smear of GFlex epoxy, prepped and all
cleaned with denatured alcohol.

Clamping is done with small spring clamps, three per scale, on a flat
piece of angle iron.

After a 24 hour cure, I remove them and notice that they are bowed from
each other, sufficiently so that if I flatten to remove the bow, the
liners will look pretty sorry.

I am trying to straighten them by clamping and over shimming where
needed and placing the affair in front of a space heater, rotating every
so often.

So far no improvement.

This has happened before and I can't stomach wasting such beautiful,
unique materials.

Any ideas for salvaging these and possibly future work?

Thanks in advance,
Scott
 
Good morning, Scott. I'm assuming you are using some sort of pin system, and I'd suggest using Corby bolts instead.

I've noticed this frequently too, and others may have more intelligent answers, but my thought is that, even though they are stabilized (I use K&G for all of mine), they are still an organic material made up of individual cells, and can still absorb moisture, (although not much) which can cause movement.
 
Good morning weo, thanks for the reply.

Yes, I will be using Corby's and sometimes solid pins. This pair definitely Corby's!
Challenge with these scales is that the warp separates inboard from the ends, centered, so the Corby's may not close the gap well.

Could the volatiles in the GFlex have migrated into the stabilized wood or drawn out some of the resin causing it to bow like this?
 
I use the maxi cure from Pops knife supply to laminate scales and liners and such, I think the heat build up from the curing g flex may be causing you issues. I’ve had very good results with the maxi cure.
Same procedure you’re doing, just swap adhesives.

g flex melts plastic cups, so it’s gets pretty hot as it cures
 
The thing about the GFlex heating up, I've never experienced anything like what's been reported.
I mix the 650 on a hard wood surface lined with masking tape according to directions. One to one.
Mix till a song is done.
After application I touch and clean the ooze, no heat felt.
Later I touch the still sticky surplus mix, no heat felt.
After a while I bring the clamped stuff into the house and set in front of a small heater, not too close.
West system says I can add heat not too exceed 120F. I'm sure I don't.
I didn't do this with the scales this time.
My hands must be dead... ;-)
 
how can you be certain they are "well" stabilized? if they bend or curl, they were not very stabilized. do not put curing scales in front of a heater.
 
Hi John.

I've had them for a while now, looked at them and others that I have, you know picking what I want to use, etc... They were taped together like a book and when I looked at them and others they were flat. I checked them before roughing and they were flat, afterward as well.
I feel that they only warped after the epoxying to the liners. These were not put in front of the heater till days afterward, after they warped, as I am trying to see if I can lessen the warpage.
And that is what I am trying to find the answer to; what cause the warpage in the first place?
 
It sounds like the epoxy soaked into the cells & caused them to expand on the side they were glued, no? If they bowed out (away from the metal surface) that's what happened. Use mechanical fasteners, clamp between 2 flat metal plates to keep things flat & hope for the best next time. It sounds like they weren't properly stabilized if the epoxy wicked into the wood and caused it to expand.

Take them off, start over & try it again would be my recommendation. No use trying to fix a botched epoxy job, as once it sets up, you're pretty much stuck with the results. Sorry, not meaning to be rude here.
 
Sorry to hear about your warped scales. If it were non-stabilized wood, I would say it is due to humidity changes. I do not know if stabilized wood still expands/contracts with changes in humidity. Putting it in front of a heater may make things worse if the moisture can escape from one side of the laminate, but not the other.

The other thing that jumped out at me reading your post was "a flat piece of angle iron". The angle iron I get around here is never flat and not ever 90°. If the angle iron is not flat, maybe you introduced the warp by clamping? Have you checked it against a surface plate?

In my experience, any epoxy can melt a plastic cup, you just have to leave enough of it in there... If I mix more than a couple ounces of epoxy, I either use it up very quickly or put it in a thin layer in a bigger pan to prevent it getting hot. I doubt that heat from the epoxy could be the problem in a thin glue joint.
 
Hubert S. said:
The other thing that jumped out at me reading your post was "a flat piece of angle iron". The angle iron I get around here is never flat and not ever 90°.
Click to expand...
That's what I've been wondering all day and mine aren't flat either. Even my granite countertop pieces aren't perfect as measured by a 60+ year old inherited carpenters square. Not by much but I really don't know which is flatter, the granite or the square?
 
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I've just checked my angle iron with a Starrette straight edge and the iron is straight along its 12 inches. I also put it down on my table saw table and not visible gaps that I can see.
I really think the warpage comes from the interaction between the epoxy and the different materials.
It is possible that the small spring clamps were unable to resist the movement during curing. Some kind of creep happening.
 
Scott
I suspect the grips are absorbing either the alchol and or the epoxy and causing the warp.
You might do a little experimenting:
take a set of burl grips you have confirmed flat, wipe the mating surface of one with the alcohol and not the other. Set them on a flat surface and see if the one with the alchol rub bowes up.

If one doesn't bow, repeat the test, wiping down both slabs with alchol, and applying a thin coat of epoxy to the mating surface of ONE slab. Set them on a flat surface, mating side down. Put a plstic newspaper bag down under the slabs. Epoxy will not adhere to the LDPE bags.
Jim A
 
I wonder what the moisture content was before it was stabilized? Could it have not been dry enough before it was stabilized?
 
DAMNENG, I'm going to try the wipe on the opposite sides of the scales, as is, first and see what happens. Also on some new flat ones that I have.
The alcohol was dry for some time before I epoxied these and I had wiped all sides down and dried with clean towels.
The bags are a good idea although I use wax paper and it works ok.

Spalted, I have no idea what the pre-stabilized moisture content was as I did not do these myself. They are heavy and were flat before adding the liners.

If I were to pre-glue the next ones with superglue, Gel or thin?
 
I use Bob Smith industries maxi cure. I find it to be just right consistency for liners. I've also used the blue label gorilla glue, thick but not gel. The dollar store stuff and regular super glue seems too thin and sets too quick for me.
 
SS369 said:
Clamping is done with small spring clamps, three per scale, on a flat
piece of angle iron.
Scott
Click to expand...
I don t say that this is reason for wrap , but .................
Next time try to clamp them with real clamp for woodworking and use force .It is BS that you can squeeze all epoxy out .
The chemical reaction between resin and hardener as epoxy cures will generate heat. When this heat cannot escape, it builds up, causing the epoxy to cure faster because epoxy cures faster at higher temperatures. Curing faster because of the heat, the epoxy generates even more heat, even faster
Click to expand...


Did you work on scale in same room where was wood been ? Wood tend to move if you change environment ...From cold place to warm or other way ......
 
When I glued liners to this scales I leave them on sun.....And after two hour they look like letter C :p I leave them back in shop and next day they was straight as before gluing :)
OXItww6.jpg
 
Hi Natlek.
Yes the scales and liners were stored in the same place, my shop. They were both at the same temperature, etc.
I didn't see any warpage because they were clamped and then I brought them into the house to warm some.
Being that they are stabilized and G10, not raw wood, I did not think there would be a challenge with warping.
Funny, but I have some other pre-glued scales, wood and G10, epoxied with the same epoxy, out in my shop that are still flat.
Perhaps there was a reaction of the resin in the scales to the epoxy...
 
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