CPO cracking

Bangback

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Anyone know how to prevent this from happening?

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I plan on replacing this repro CPO with a new one, but if anyone has any hints on how to prevent it from cracking again, I'd be grateful.

This game was stored in my basement, in a controlled environment, low humidity, with no exposure to light. It also didn't get very much game play.

When I first put it on years ago, I put a layer of contact cement on the wood, let it dry, then used the adhesive on the CPO and applied it to the wood. It looked perfect and all the curves were smooth.
 
I'd like to know too. Would a blast from a heat gun after it's on help bend it and "melt" the plastic as opposed to it being forced against it's will? Dunno...
 
Hmmm. It might. I can give that a try.

I noticed that the overlay has started to separate from the wood, as if the adhesive had worn out.

Maybe something stronger would keep the curve and prevent the cracking?
 
I wonder if the contact cement didn't hasten the failure of the overlay? Depending on the make-up of the cement, it could induce a failure on the overlay adhesive.

The Williams control panels can be a little challenging, I always make sure the wood is not only smooth, but sealed and not flexing along the seams. If it is, some wood glue & clamps will fix it right up. I wouldn't add any extra adhesive, the extra layer might be soft enough for the CPO to flex and crack again.

I've also experimented with using a heat gun to relax the Lexan layer in the overlay after installation and so far it seems to work. The caveat is this: the difference between relaxing the overlay as it bends around edges and melting is a very small one.
 
I removed the old overlay and adhesive last night.

With the contact cement / adhesive combination, it was very difficult to remove. I had parts of the wood coming off with the overlay, as well as some other areas where the overlay came off but the artwork and adhesive stayed on the wood.

So I don't know if it was an issue of the contact cement affecting the holding power of the adhesive.

After I bondo it and sand it, I'll just try it this time around with just the adhesive alone, and use a heat gun for the bend.

Thanks for the tips!
 
Heat gun is key for bendy, sticky action! Just be careful, and be warned that it WILL show every imperfection on your CP if there are any. Sand her good!
 
What's the favored technique on this?

So first apply the top. When I get to the bend, use a heat gun, and I'll just want to get it hot enough to where it will droop from its own weight? Or is it too hot (and too late) if I get to that point?

Or is it better just to apply it first with the bend, and then heat up the bend to set it in place? Because, it doesn't crack right away -- only after a long time will it begin to crack.
 
I too have this same problem. I bought a Robotron that had a new CPO installed and it looks just like the OP's.

When I replace mine, I was thinking of using a hair dryer on the hot setting - it shouldn't get as hot as a heat gun where it would melt or distort a new CPO.

Let us all know how things work out for you!
 
This is what I was trying to avoid when I started this thread: http://forums.arcade-museum.com/showthread.php?t=188579&highlight=cracking

You never mentioned where you got the overlay. Do you know the material and thickness?

I once mentioned that heating an overlay can actually reduce it's life and another forum member took exception to that.

For making custom overlays I'm actually looking for a relatively thin material that is still durable, so that it would have less of a tendency to crack over time.

Darren Harris
Staten Island, New York.
 
I bought the Robotron CPO a while ago. I can't exactly remember who I got it from, but I think it was at Pinball Expo around 1999. I didn't bother to put it on my machine until several years later. It is screened art, not inkjet.

The one that was cracking was pretty thick. Comparing it to the screened replacement I just got from Arcadeshop, it's a lot thicker!

I don't have a micrometer, so I can't measure it.

I received the new CPO rolled up like a tube with a rubberband. So would it be already compromised since it's already been curled with a tight radius? I flattened it out with a couple cans of soup, and it appears OK.

So what was the consesus? Better to use a heat gun on the curve, or not?
 
I haven't used a heat gun yet for any of my CPO installs, but I would barely heat it up...don't heat it until it droops. All you would be trying to do would be to barely reduce the stress generated due to the bend. Keep the gun moving constantly and barely let the heat hit it.
 
This question has been debated for years on these forums and its seems certain overlays are more likely to crack than others and various methods work for different people on different overlays......what I've found works for me very well is to take the overlay and simply clamp it down to the panel for several weeks while not removing the adhesive...if your patient enough to do this...this allows the cpo to conform to the general shape of the panel with no strain put on it from the adhesion to the wood or metal...then after a few weeks it it will naturally conform to the panel its been clamped too...then you remove the backing and see how it is after a few years...the few I've done this way seem to hold up well...I think having the cpo already conformed to the general shape of the control panel your applying it to takes stress off. You tend to get better adhesion of the overlay at the stress points of the panel when applied like this....of course a cheap repro will always crack due to the cheap material..but if its a good repro...it should hold up well with this method...the key is to clamp it down or tape it and forget about it for a few weeks....IMO
 
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