Chip Flattening - Chips Got Squished (1 Viewer)

[Davism72]

Picked up some well worn starbursts recently to practice milling, but they came pretty warped. Perfect opportunity to practice flattening, also!

I follow the common advice here: wooden clamps, ceramic spacers, low heat, let cool. The results were not what I expected, though. The chips did get flatter — not completely flat, but certainly not as bad as they were — but they also got really squished. On my second attempt, I almost completely squished out the mold. See pics below. No flattening, first attempt, second attempt, from left to right.



And all together.



Anybody have advice? The oven was at 160, and I’ve heard dissenting opinions about temperature. This is as low as mine will go.

I was also clamping REALLY hard. Like, as hard as I could. I think this may be the problem. How hard are you supposed to twist? How long should the chips sit in the clamps?

 

[Beakertwang]

I have no advice to offer, but I’m curious: Did the flattening increase the diameter, as well?

 

[ReallyGoodUsername]

Picked up some well worn starbursts recently to practice milling, but they came pretty warped. Perfect opportunity to practice flattening, also!

I follow the common advice here: wooden clamps, ceramic spacers, low heat, let cool. The results were not what I expected, though. The chips did get flatter — not completely flat, but certainly not as bad as they were — but they also got really squished. On my second attempt, I almost completely squished out the mold. See pics below. No flattening, first attempt, second attempt, from left to right.

View attachment 272963View attachment 272964View attachment 272965

And all together.

View attachment 272966View attachment 272967

Anybody have advice? The oven was at 160, and I’ve heard dissenting opinions about temperature. This is as low as mine will go.

I was also clamping REALLY hard. Like, as hard as I could. I think this may be the problem. How hard are you supposed to twist? How long should the chips sit in the clamps?

Sorry to hear it didn't work out. Do you know if these are leaded or unleaded (not sure it would matter but more info the better)? How long did you have them in the oven?

I twisted my clamps until they were "snug" then did one more twist. I kept mine in for 15 minutes w/o/e I believe but they're weren't hotstamps.

 

[Davism72]

I have no advice to offer, but I’m curious: Did the flattening increase the diameter, as well?

Yes, a bit. Flattened chip on the right.

Sorry to hear it didn't work out. Do you know if these are leaded or unleaded (not sure it would matter but more info the better)? How long did you have them in the oven?

I twisted my clamps until they were "snug" then did one more twist. I kept mine in for 15 minutes w/o/e I believe but they're weren't hotstamps.

I’m not sure about leadedness. They feel pretty standard to me.

Not sure what w/o/e means. By snug, do you mean you could have twisted more if you tried? And you’re happy with the results? How long were they clamped?

 

[Pesky]

I would say that you should make the clamp just snug, warm it up and then make it a little more snug, warm again and the just a little more snug, you could use a non warped chip as a guide on how snug to make it.

 

[Potsie1]

Use very light pressure. You definitely clamped too hard. Time is as important as temp and I dont see an answer to the question. How long were they in for? At 160 which is on the high end I wouldn't put them in for longer than 10 to 12 minutes.

It would be better to apply a lighter clamp and let them cool. You can run them through again to finish the job. Minimal pressure.

 

[ReallyGoodUsername]

Yes, a bit. Flattened chip on the right.

View attachment 272973



I’m not sure about leadedness. They feel pretty standard to me.

Not sure what w/o/e means. By snug, do you mean you could have twisted more if you tried? And you’re happy with the results? How long were they clamped?

Without error (no issues/smooshing). Snug meaning I couldn't push the chips out of the clamp without serious force but at the same time could still tighten them further. Can't find @Potsie1 's flattening thread but I followed the time/temp exactly and had no issues. My oven only goes down to 170 so I cracked the door open with a cooking sheet. Tightened the chips again when they got out of the oven but only slightly.

 

[Davism72]

Time is as important as temp and I dont see an answer to the question. How long were they in for? At 160 which is on the high end I wouldn't put them in for longer than 10 to 12 minutes.

On my second attempt, they were in the oven for 30 mins and in the clamp for another hour after I pulled them out of the heat. I was clamping as hard as I could the entire time. Seems ridiculous now, lol.

Would love a link to your thread if you have it.

Snug meaning I couldn't push the chips out of the clamp without serious force but at the same time could still tighten them further.

Yes, this seems like where I went wrong. I’ll try much less force next time.

 

[Taghkanic]

Did you alternate the Paulsons with ceramic blanks when you flattened them between the clamps? That is the recipe for success, in my experience.

Also, a half-hour seems way too long. I go 6-12 minutes at a time. Can always put them back in if it doesn't work; hard to undo mistakes resulting from excess time or heat.

 

[BGinGA]

Pressure was too high, and the temperature was WAY too high. Chips should be snug, not super-tight, and temperature should not exceed 120F degrees maximum -- your high temp/high pressure combination created material that became too soft, and was pressed too tightly (causing deformation, rather than flattening).

You can still use your oven as a flattening chamber, even if the heat setting doesn't go below 170 degrees. Simply place a 100-watt light bulb into the oven as your heat source -- that will generate the appropriate temperatures, while the oven's insulation will maintain that heat level. Clamp snugly, warm for 15-20 minutes, then slightly tighten, remove, and cool. Repeat if necessary.

 

[Davism72]

Did you alternate the Paulsons with ceramic blanks when you flattened them between the clamps?

Didn’t have blanks so I sandwiched each chip between some of the chipco $1s from the chip room.

Pressure was too high, and the temperature was WAY too high. Chips should be snug, not super-tight, and temperature should not exceed 120F degrees maximum -- your high temp/high pressure combination created material that became too soft, and was pressed too tightly (causing deformation, rather than flattening).

You can still use your oven as a flattening chamber, even if the heat setting doesn't go below 170 degrees. Simply place a 100-watt light bulb into the oven as your heat source -- that will generate the appropriate temperatures, while the oven's insulation will maintain that heat level. Clamp snugly, warm for 15-20 minutes, then slightly tighten, remove, and cool. Repeat if necessary.

All good tips. I don’t have a way to get a lightbulb into the oven. Maybe the built in light would work? If not, I’ll try the cracked door method.

 

[BGinGA]

I don’t have a way to get a lightbulb into the oven.

About five bucks total at Home Depot -- extension cord, light bulb receptacle, and 100-watt bulb.

 

[Davism72]

About five bucks total at Home Depot -- extension cord, light bulb receptacle, and 100-watt bulb.

Huh. Had no idea that existed.

 

[BGinGA]

We're here to help. It's called enabling.

 

[XBobdog]

Its more a low and slow process then fast and hot.

My oven also has a min set temp (mine's 150) so I turn it to that and turn the oven off as soon as hits about 130.
chips are put in with mild pressure and retightened after 10-15 min. Then I just forget about them until they cool.

 

[studioapc]

I have had success clamping barrels between ceramic tiles... I also started them off slow by clamping several barrels till they were snug but not too tight and then placed them in a warm place ( I live in the Northeast ) like on top of the boiler in the basement for a day. Then next day I would tighten them a bit more and put them in the oven after I had preheated and turned off the oven... let them sit then cool.... overall lower and slower without over tightening

 

[Taghkanic]

I would find it hard to overtighten the wood clamps with the Bessey model. The handles are kind of small and slippery. So unless I used some rubbery potholders and a wrench, there’s a limit to how tight I can twist them, though I’m used to doing a lot of manual labor... But then, I stopped taking steroids years ago...

 

[Davism72]

Not sure which model I have. Just borrowed a few clamps that looked right.

I’ll try another batch without tightening as much and report back. Thanks, everyone!

 

[Pesky]

oops, wrong thread

 

[RainmanTrail]

160F is way too hot. Paulson's are softer than TRKs, and I flatten TRKs at no more than 130F. I wouldn't get it any hotter than 120-125F for Paulsons. Do the incandescent light bulbs in the oven trick to heat it to 120F and use a meat thermometer probe to check the temp.

 

[ReallyGoodUsername]

Semi off topic does anyone know where I can get 43mm ceramic blanks? A few jack high denoms are slightly warped

 

[Davism72]

Quick update here. Tried another small batch again using the low and slow technique. Had the chips lightly clamped and in the heat for 10 minutes. Tried to maintain a temp of 130 by opening the oven door. When I pulled them out, I tightened the clamp a very little bit, then let them sit for about an hour.

Good news: no deformation. Bad news: no flattening. Like, not at all. They look like potato chips.

What am I doing wrong, guys? Frustrating stuff.

 

[RainmanTrail]

Tighten the clamp. I crank mine down pretty tight before putting them in the oven. But don't clamp them down again too hard after they've warmed up, that'll squish them. You can soak them in warm water before too soften them up enough for the clamp. Also, keep them in the oven for longer. Try 25 minutes or more

 

[RainmanTrail]

Also, lights bulbs in the oven > oven on at 175F with the door ajar

 

[Davism72]

Tighten the clamp. I crank mine down pretty tight before putting them in the oven. But don't clamp them down again too hard after they've warmed up, that'll squish them. You can soak them in warm water before too soften them up enough for the clamp. Also, keep them in the oven for longer. Try 25 minutes or more

Will try all of this next time around. Don’t want to have to baby the oven for a half hour, so I guess the light bulbs are the only way to go.

Out if curiosity, do the chips even need to be clamped while they’re in the oven? Given what you said about the warm water, maybe it would work just as well to have them unclamped in the oven to soften up, then clamp when they come out.

 

[MaxB]

all of you are doing this the hard way and the wrong way .... instead just contact the expert and he will help (probably has a tv show on his network for warped Paulsons)

 

[Jeff]

Upside: 43mm chips?

 

[Davism72]

The squishy silver lining.

 

[Shaggy]

Out if curiosity, do the chips even need to be clamped while they’re in the oven? Given what you said about the warm water, maybe it would work just as well to have them unclamped in the oven to soften up, then clamp when they come out.

What is basically going on is:
1. Chips start out as happy taco shaped poker chips
2. When you clamp them together, they are flat, but they have a bunch of stress inside because they are being squished.
3. Toss 'em in the oven on low heat or the lightbuld method (lower heat). The heat slowly penetrates the chip... like cooking a steak.
4. As the temperature increases in the chip, those stresses relax... like a sauna. Once the center of the chip gets up to temp, the internal stresses have all relaxed.
5. Now the chip can cool while still clamped. The maintained clamping prevents the chip from cooling in a non-uniform way and inducing more warping.

The keys here are that the (1) temperature is high enough to get above the recrystalization temperature (not proper term... but similar) of the plastic and that (2) the time is long enough to penetrate to the center of the chip.

It has been shown that 25 minutes at ~100 deg F works.

http://plasticsannealing.com/

 

[Davism72]

Thanks for the detail, @Shaggy. It's great to know what's going on in more detail.

Another update. I tried another small batch. I clamped the chips down as hard as I could, then backed off a bit. (Wish there was some better way to quantify this.) The chips were definitely under more pressure than my last test. Still no lightbulb hookup, so I stayed with the oven's internal heat. Kept the temperature at 115 +- 5 degrees for 20 minutes. When I pulled the chips out of the oven, I did not tighten the clamps at all. Left them in the clamps for the longest duration yet, just over five hours.

Results: Still absolutely no progress. Wtf.

Not sure where to go with here. My gut says to try low heat with harder clamping, but according to the advice above, the problem seems to be that my chips aren't getting hot enough to relax.