Awesome post.. Thanks for the info! I'll be using this technique next time I have some plastics that need flattening.

good job!

Clean them with Novus 2 or your favorite cleaner before heating them. If they become soft enough to flow flat you do not want any dirt possibly embedding in the plastic. Clean glass surface also.

Awesome...and good point cal, it can be difficult enough to get the dirt out as it is

I've had to faltten a few plastics. I avoid the oven, guess i'm chicken.

Outside on a hot day works great between 2 plates of glass (cooking for a few hours).

Also, using a hair dryer works well. Its not quick, but the risk of screwing up the plastics is very low. Again, once the plastic is soft, sandwich the plastic between 2 plates of glass.

i've always done the heat gun plus 2 pieces of playfield glass.. prep work involves novus to polish them up cause you dont want to imbed the dirt in to the plastics....

Ive done probably half a dozen games this way a the heat gun I use is from Ace hardware, runs about $30

Polish up plastic, lay on one sheet of glass, heat til you see it start changing shape then move the other piece of glass on top of it so it will cool flat

Thanks for that - going to have to be doing this soon for my Getaway plastics as well.

Well beats sending them to Japan and having some sumo wrestlers sit on them!! LOL

Wow! I hadn't thought of that. I did the 'normal' oven thing once and ended up with some bubbles in the plastics.

Are there any other oven settings that are important like using hot air/ broil etc.?

With no access to a heat gun and too chicken to oven bake them, I also used the hairdryer method (but with books and a bit of pressure)

Took a lifetime gradually heating and pressing at a comfortable pace for me.

Worked and no risk though

Thanks for the instructions! I will be giving this a try, I have 3 machines with very warped plastics.

We do the glass in the oven (or sun) trick for dewarping vinyl records all the time in the DJ world. Works pretty good but you have to be careful.

what's the best way to get smaller pieces of glass for this?
-mof

I sure as hell wouldn't do 225 degrees. I do this at 150 and it affords me a higher degree of safety.

I live near an Ikea and got 2 small glass shelves. They have rounded edges and were cheaper for me than buying glass from a 'glass store'.

Remember, that some of the affect comes from the weight of the glass. If you go too small you won't get enough pressure. Recently they've actually come out with a vinyl flattener product (as opposed to the DIY way we used back in the day). Something like this may even work better.

http://vinylflat.com/vinylflatproducts.html

I read this thread last week and had a warped piece of plastic that I wanted to flatten. Looked around for pieces of glass and found my wifes pyrex cooking collection. Put the piece of plastic on top of the bottom of a pyrex pie dish and put another pyrex pie dish on top of it. Took about 40 minutes at 170. I turned the plastic piece over about half way through. It's now almost perfect. Thanks OP!

Thanks for the help, I have a few pieces for a Stern Lightning that need flattening (and if you know the game you know to which ones I refer).

Thanks for the Pyrex idea, that's something we have around here! Cheers.

So there's no concern about glass touching the ink side while at 175°f ?
-mof

Nice, using this method soon.....

I guess you missed my post on this topic in the Getaway thread: https://pinside.com/pinball/forum/topic/getaway-club-dispatch-run-a-make-on-license-plate-kingpin/page/85#post-3476073

Sometimes you do not have to reheat wrap plastics back into shape based on severity.
Various pinball designs of the past with long plastics did not use proper reinforcement which caused the bending in the first place.

If you add a post and spacer in a key point (I am not advocating drilling a new hole in the plastic itself) UNDERNEATH the plastic you can "shim" the plastic upwards into its correct flat height, and make fine tune adjustments with the outer screws in tension.
This way the plastic is permanently supported correctly, and not sag again over time.
After attaching the metal screw with the spacer and T-nut under the playfield, add a *tiny* piece of rubber technicians tape on top of the screw (not the plastic itself) or small PETG washer to prevent scratching the plastic, but still allow it to be removed, as required.
If you do it right, it will be nearly invisible, and not affect lighting.

I just did this with some seriously warped plastics. My oven only goes down to 170F. I put them between glass and heated them for 45 minutes. Pulled them out, put a hot pad on top, placed a heavy object for 10 minutes. Then removed the weight and let cool to room temp. Perfectly flat.

Wake up old thread!!

So usually when I shop out a game, I buy new plastics if they are available. I am shopping out my recently acquired Grand Lizard right now. Even though Marco has plastics, The ones in the game were just a little warped, not broken for a change. So I decided to resurrect this thread and try the method described. First I got 2 pieces of glass cut. 18" x 16" x 1/4" seemed to be a good way to go for my oven. 10 bucks a sheet with sanded edges! I thought was real fair.

Hentges Glass
Address: 1631 Voll Dr NW, Byron, MN 55920
Hours:
Closed ⋅ Opens 8AM Mon
Phone: (507) 282-1769

So in a nutshell, I sandwiched most of the set between the glass sheets, ran 170 degrees in the oven because like the last poster, that is all the lower the oven will go. Left them in there for an hour, let cool down on the stove before removing top sheet of glass. Presto. Flat as a pancake plastics ready to install. Really happy with the results!
DSCF7268 (resized).JPG

Reviving this thread because it was helpful and I just wanted to add my technique to the multitude of techniques on here.

I didn't see the reason that glass needed to be used for the oven technique, other than needing to see the plastic. From what I gathered nobody had any shrinkage (insert jokes) problems or other issues with their plastics that required constantly visualizing there plastic in the oven. My Stars manta ray plastics were too big for the pyrex techinique (that worked well btw for the small bits) so I just used 2 cookie sheets and parchment paper (not wax paper as noted in another thread). I set the temp at 170, sandwiched the plastics (upside down cookie, parchment, plastics, parchment, right side up cookie, Le Creuset dutch oven pot for weight) and set the timer for 45 minutes. The dutch oven (again insert joke) is basically the same weight as a engine block so that helped a bit I suspect. One small curve still remaining on the end of one of the manta ray plastics but otherwise success without loss of paint or other problems.

Interestingly as I was cleaning the plastics before the process one of the plastics sat in a pool of water for just a few seconds and paint flaked off. Water was the last cleaning product that I would have thought would wreck the print on the plastics so don't let your plastics soak even in a small amount of water.

I wanted to add my experience here. I had a moderately warped Space Shuttle, HOT NEW PINBALL topper plastic. I didn't want to destroy my sign, but, worst case, I knew I could buy another plastic set for around $150.

I cleaned the sign with Novus #1 first. Then I heated the oven to 170F (I'd prefer lower, but this was the lowest setting), and set a timer for 10 minutes. I put the sign, face up, in a no-stick, very smooth and flat roasting pan that was larger than the sign. I'd prefer a glass pan, but didn't have one big enough.

I watched the entire time. After a few minutes I could see the sign gradually flattening on its own. I left it in for the entire 10 minutes, then shut the oven off and opened the door about 6 inches to let it cool gradually. After the oven cooled down, I pulled the pan out and let it cool to room temperature.

The sign came off the pan easily and was perfectly flat. After careful inspection, I could not see any damage to the sign.

I still think this is a risky procedure. I wouldn't try it on something that could not be replaced.

Any thoughts on how to best flatten this bad boy? I've got glass to flatten the other plastics on this game with, but this piece has me stumped. Those two posts are not removable, and protrude on the top side a bit, so the piece will not really lie flat. The rest of the piece is not too bad, and I think I could simply put the long tail between glass, but this wrinkle between the posts has me baffled.

plastic1 (resized).jpg

Those are removable, heat up the bell posts enough with your soldering iron to soften the plastic and pull the posts out, repeat to re install

Thanks for the tip! Hopefully a fairly cool soldering iron will provide enough heat, but not enough to discolor the artwork or melt the plastic. Do you recommend heating from the underside, or just a quick touch on the top surface?

It might be covered in here, been a while since I looked through it:

https://pinside.com/pinball/forum/topic/removing-amp-installing-bell-posts-on-new-plastics-vid-s-guide

Another Vid guide - I should have known!! Don't know how I missed that one.

Bell posts removed, and plastics safely and successfully flattened!

Thanks again!