(Topic ID: 33465)

Repairing a cracked backbox


By Finrod

6 years ago



Topic Stats

  • 11 posts
  • 7 Pinsiders participating
  • Latest reply 6 years ago by Finrod
  • Topic is favorited by 1 Pinsider

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#1 6 years ago

I have a 1985 Williams Sorcerer with a problem I've never seen addressed before. The bottom of the backbox has a very nasty crack in it that goes the entire width of the machine. This crack is causing the backbox to lean forward precariously; right now I have a piece of metal with two wood screws (one above, one below the crack) that's quite possibly the only thing keeping the backbox from cracking the rest of the way and crashing down onto the playfield box. The crack is as much as 2-3mm wide looking at it from the back of the machine.

Anyone have any advice about how to go about repairing this? My tentative plan of action is to use Q-tips to get wood glue inside the crack, then take off the back legs so the backbox is leaning backwards to close the crack, and leaving it that way until it sets and dries. Does that sound like a reasonable plan?

#2 6 years ago

I would remove the backbox and use clamps.
Moisten the crack with water and use a toothpick to work some Gorilla Glue into the crack then clamp it.

#3 6 years ago

Tracelifter is right on with his recommendation but I would take the backbox to a local cabinet shop. They can dado cut the bottom of the backbox and reinforce with strips or planks of a good hard wood - do it right the first time.

#4 6 years ago
Quoted from tracelifter:

I would remove the backbox and use clamps.

+1

I did a similar repair and used construction adhesive which for me worked well because it can fill in small spaces if the joint isn't a perfect fit. It's also sandable & paintable.

#5 6 years ago

Here's how I've done it in the past.

Get a hardwood 2x4. Cut one piece that will barely fit between the inner backbox walls
Cut a 2nd piece that will span the underside of the backbox

Flip the backbox upside down. Inject titebond wood glue into the splintered/cracked spots generously. Use a chip brush, syringe, q-tips, whatever you have. Using the 2x4 pieces, clamp the bottom panel of the backbox and pull it 'square' Some wax paper on the 2x4s may make it easier to get the 2x4s out, as the glue will attach them to the backbox otherwise.

Let it dry for a few days, unclamp, touch up paint.

This method has held up OK for me long-term; if you could disassemble the backbox, perhaps you could cut a replacement lower panel and just swap that panel.

#6 6 years ago

I thought about using clamps, but I'm not sure that the clamps that I have are deep enough to be able to reach all the way to the back of the backbox from the front, since the only other place I could put the clamps are inside the hole that the cables go through into the body of the machine, and that wouldn't apply pressure on the outside parts of the crack at all.

I'll have to do some measuring and see whether the clamps will reach or not. The only other option I can think of is turning the backbox upside-down and stacking weight on top of it. I'm certainly not enough of a carpenter to try replacing the bottom panel entirely.

#7 6 years ago

Hi!

Here on the bottom of the page you can see, how I made it...

http://pinside.com/pinball/forum/topic/bally-xs-os-1984/page/2

#8 6 years ago

I took another look at my Sorcerer, and remembered the other reason I was trying to think of a solution other than using clamps-- Sorcerer is a System 9 and the speaker panel is bolted in there tight, unlike my System 11s where the speaker panel lifts right out. I'd probably be able to unscrew the speaker panel, but it'll add a good bit more work to the job.

#9 6 years ago

I can tell you the wrong way, which is what some previous owner did to my Gulfstream.
Do not use perforated metal pipe strapping strips around the outside of the backbox screwed into the wood with rusty screws and washers.
That's a crime that should not be repeated.

3 weeks later
#10 6 years ago

It turns out the crack in the backbox isn't where I thought it was. The bottom of the backbox has separated from the back of the backbox, so clamps aren't going to help, and I found out I didn't need to remove the speaker panel (a real pain to remove) until I already had done so.

I'm thinking after I attack this with wood glue and some kind of nails, of getting a backbox latch like the System 11 games have and installing it, because that would fasten the back of the backbox to the main body of the machine and take the stress off the back/bottom crack area.

3 months later
#11 6 years ago

What I ended up doing: I used wood glue and a handful of wood screws to fix the crack. I had to be careful because I couldn't put wood screws into the bottom of the backbox where the backbox rests on the neck of the body, for obvious reasons, so the screws ended up in the left, center, and right parts. It was a 2-person job, one to hold the backbox down to close the crack and the other to drill the pilot holes for the wood screws. I haven't reassembled it yet but I also bought two of the System 11-style backbox latches that I intend to install after reassembly.

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