Flatten a plastic backflash

Advice and guidance on repair and restoration techniques.
junior
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Re: Flatten a plastic backflash

Post by junior »

Glass will not shatter if it’s toughened glass. Same as oven doors. The plastic I tried to flatten was only 75mm x 50mm and thicker than a sheet of clear backflash. It got hot in electric oven all over enough for me to change its shape.
Took about 5 repeated easing into shape but now it’s OK to go back into the machine.
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badpenny
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Re: Flatten plastic

Post by badpenny »

I think gentle persuasion may be the secret to this greg.
Try laying it between two pieces of single ply wood sheeting and then place the largest flat bottomed pan you can find on top and fill it with boiling water.
Keeping the water hot and repositioning the pan in order to give all of the back flash a chance may produce results.
What sort of results you'll get could be a bit of a mystery, but at least you'll be more informed than us.
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coppinpr
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Re: Flatten a plastic backflash

Post by coppinpr »

You might try looking at methods used to flatten warped 78rpm records. There are several methods, most are on youtube I think. I even saw one once using very hot water. !OMFG!
greg
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Re: Flatten plastic

Post by greg »

Thanks for all the great suggestions on fixing the playfield. Here is what I have tried in the past and also what I did this time.

Try #1. On another Allwin, I completely removed the playfield from the game and tried to evenly heat the entire thing with a heat gun. I thought that if I got the entire thing to the same magic temperature it would just flatten all on its own like a good little play field. It didn't and I wound up melting one corner.

Try #2. I decided it needed some weight on top while I was heating it. I placed a large sheet of glass on top of the play field and some heavy weights on top of the glass. I then heated the glass for a long time with the heat gun. Not enough heat was getting to the playfield and eventually the glass shattered.

This time #1. I decided to try flattening the playfield in the game. I removed the 12 winning hole thingie. Just 4 screws on the back so that was easy. There were 4 tiny nails in the plastic just above the holes. They took a while to get out because I didn't want to crack the plastic were they were driven in. Then I took out my heat gun, set it on low, and heated one small section for about 30 seconds. No change so I touched it to see if it was hot enough. It was and have the burnt finger tip to prove it.

I decided I needed to protect my little paw so I got out the old family asbestos gloves. If you don't have a pair of asbestos gloves sitting around an oven mitten will work. Just don't use the one with old food stuck to it.

This time #2. I applied heat to the playfield, one small section at a time. Then stopped the heat and I rubbed it (with my gloved hand), pressed it flat, held it as it cooled and told it that it was pretty pretty playfield. I kept repeating that over all the bad spots. It only took about 15 minutes and it was flat enough to work again.

I had to trim the plastic a little around the slot where the 12 winning hole thingie goes. I also didn't put the 4 tiny nails back in. They were a big part of the reason the play field buckled.

I don't know how well you can see it in the earlier picture but the playfield was buckled all the way across the top of the winning holes and it was impossible to get the ball in any hole.

The playfield isn't perfect but game plays great now and that is all that really matters.

Thanks again for all your help.
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bryans fan
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Re: What is it?

Post by bryans fan »

Thanks for giving such a detailed account of the various methods you tried. Very interesting. I think it was well worth saving rather than replacing with new. Well done.
!!YIPPEE!! !!THUMBSX2!! **xXx**
I have been dithering over my Pilwin back flash for 10 years!
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yaksplat
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Flatten a plastic backflash

Post by yaksplat »

This topic copied & edited merged from Help with Win a Crunch - Site Admin.

Is there a good way to smooth out the artwork? There is some warping. It's not horrible but would be nice to flatten.
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coppinpr
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Re: Flatten a plastic backflash

Post by coppinpr »

The backflash can, I believe, be flattened and I think there is a method within the forum somewhere, much the same as correcting warped records with heat I think, but remember you need to remove everything to get at the backflash. You will find it's shrunk and pulled against the pins. Removing it might release a whole new set of problems.
Last edited by coppinpr on Thu Feb 28, 2019 9:15 am, edited 1 time in total.
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brigham
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Re: Flatten a plastic backflash

Post by brigham »

My Whales 'Easy Perm' backflash is the same. I've learned to live with it; they often turn brittle, and start to crack when you handle them.
It had a MBC lamp holder in the top box, even though the artwork was almost opaque. Probably contributed to the warped top flash.
tammy
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Re: Flatten a plastic backflash

Post by tammy »

I wouldn't try fattening the backflash, as they are back painted and the paint may at the least start falling off. It doesn't look bad at all. I trust you will enjoy the machine.
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yaksplat
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Re: Flatten a plastic backflash

Post by yaksplat »

It looks like I'm going to need to trim the backflash around the exit hole as it has shrunken, covering part of the hole.

I may just take the playfield and create a new one from it, leaving the original backflash attached to the original playfield. I could get a new one printed on vinyl and fit perfectly to the new playfield.

The original colors on the backflash look good.
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gameswat
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Re: Flatten a plastic backflash

Post by gameswat »

...As for the backflash, that's a very nice original so not sure why you would want to replace it? A repro is never going to better it. Because the plastic has shrunken over time you need to release the tension where any pins or screws attach through it and are locking those parts in place while other areas can stretch, which then causes the buckling. I just elongate the holes slightly with a Dremel or re-drill new ones in bad cases, just enough to leave a little bit of wiggle room for any further shrinkage. Looks like you have one bad split on the top lhd, which should be easy to fix by releasing that corner piece and bringing the joint back together. The plastic goes well under the side wood spacers giving you a lot to play with. I've sometimes had to use tiny brass nails to hold down cracks like that if they keep wanting to lift up and stop the ball. But I've also used a clear layer of polycarb over the top of badly warped ones to help keep them flat too.
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yaksplat
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Re: Flatten a plastic backflash

Post by yaksplat »

I removed the backflash as it was so warped and cleaned up the playfield an all of the parts. The backflash is much nicer with the layer of dirt removed. I may have to put a layer of plexiglass on it as Gameswat suggested.
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yaksplat
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Re: Flatten a plastic backflash

Post by yaksplat »

Looking better already. It took quite a bit of heat to flatten out the backflash. 300ºF in the oven. I started at 170ºF and increased at 20º increments until it would be soft enough to flatten. The paint on the backside is very delicate, so I lost a few flakes around the existing holes. I had to drill new holes through the backflash for all of the pins and screws as everything had shifted by a few millimetres.
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coppinpr
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Re: Flatten a plastic backflash

Post by coppinpr »

Looks great. Did you try touching up the paint from the back of the backflash? This can work well on small areas, but always add a top coat of matt white.
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yaksplat
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Re: Flatten a plastic backflash

Post by yaksplat »

I thought about doing some painting on the back, but for the few small areas, it won't really be worth it to acquire the paint, match the colors and then get it perfect. If I leave it at is, there's some paint flecks missing and that's because it's old. If I paint it and it doesn't match perfectly, that will annoy the crap out of me. If it does start to bother me, I can always do it later.
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Re: Flatten a plastic backflash

Post by 13rebel »

Brave of you to use the oven method but by including the method it may encourage others to be equally brave. The idea of leaving the paintwork on the back as it is in case you can't match it I think is good too. Best to see if you can live with the aged look.
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badpenny
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Re: Flatten a plastic backflash

Post by badpenny »

I think that apart from the temperature that you found necessary to bake it at, what is equally important is approximately how long before it was pliant.
And, did you place it in the oven paint up or down?
What process did you employ to even it out? Was heat and gravity enough or did you put something heavy on it?

I ask as I could imagine getting any of those steps wrong could easily nause it all up in spectacular fashion.
I think you were very brave and thank you for bearing the mantle of guinea pig on behalf of the hobby.

BP !WORSHIPFULL!
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yaksplat
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Re: Flatten a plastic backflash

Post by yaksplat »

So, as you can see in the earlier photographs, there was one corner that was cracked off and it was a pretty decent size and it was extremely warped. First thing I did was place down on a piece of paper, held it flat and traced it. At that point I had the original size. I had feared that the heat would potentially make the plastic shrink, which would be a complete disaster. I kept putting this piece back in the oven for about 10 minutes, which was long enough for the plastic to reach the temperature of the oven. Then I'd take it out and I'd lay it on the piece of paper and sandwich the piece between the counter top and a cutting board, putting my weight on it. The temperature would drop quickly and then I'd check the piece for size against the outline I took, and deformity. The size never changed, which was great. But it was still warped for many iterations. I kept doing this, over and over, while increasing the temperature until the piece was relatively flat. Once I determined that 300 was the temperature, I threw the whole thing in, left it for 10 minutes and then attempted flattening. It wasn't perfect, but worked well enough that it no longer looks deformed. All of the nail and pin holes were completely flat.

If I was to do it over again, I'd probably keep going higher and use two pieces of glass to sandwich the backflash. I'd place a 30 pound weight on the glass once I pulled it from the oven and then let it cool slower between the panes of glass. I'd suspect that it would flatten quite well in that scenario.

At one point I couldn't find my corner piece. It had fallen off of the rack in the oven and was sitting against the back wall, touching the bottom of the oven. I'm not sure how it didn't completely melt. But that could have been disastrous.
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coppinpr
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Re: Flatten a plastic backflash

Post by coppinpr »

Somewhere on this forum, years ago, we looked at the method of flattening warped 78rpm records without affecting the grooves. If I remember correctly this was much like your "next time I do it" using glass on both sides (although I guess the temp would have been less).
Really well done, a ground breaking repair !THUMBS!
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