GC 1 installation mechanic callback

[tjohnson]

Backstory:

I had my GC 1 set up and recovered by a local mechanic. Shortly after this, I noticed that slow-rolling balls along the side rails would gently roll away from the side rails towards the center. I pulled out my Starrett level and sure enough the play surface was not level - high on the sides, lower in the middle. Not severe, but definitely present. This could be uncorrectable "swayback" because of the Brunstone, but I also crawled under the table and noticed no shims were used in the centers of the slates (and only three or four shims total were used, all at the edges). In fact, there is even a small gap between the center cross-support on the base and the directly overlying slate backer-board ( I can jiggle the cross-support). So, this issue may be uncorrectable but the complete lack of shimming in the center leads me to think it MAY be at least partially correctable.

After many calls, the store finally agreed to send the mechanic back out to address the level issues. Before this happens, I was hoping to get a couple questions answered so that once the mechanic is here, I am armed with some knowledge in case he proposes some solutions that don't seem right. I don't have an enormous amount of confidence in these guys...

Questions:
So, here are my questions:

1. If he is going to attempt to shim the Brunstone (and I am already aware of the Brunstone brittleness issues and the best way to attempt shimming, thanks to RKC) he must remove the rails and cloth first so that he can loosen the screws holding the slate down, correct?

2. He used Durham's Rock Hard putty to cover the joints. It seems to me that any adjustment/shimming of the slates will likely crack this stuff so he probably should plan on redoing the joints. Is that also correct?

Any other issues I should be aware of before the mechanic returns? I definitely want to avoid having the call-back create more problems…

Many thanks!

 

[fastone371]

I had the same issue with my GC, I set it up myself and just plain screwed up. I tried to raise the center without disassembling and I split a seam, I used Bondo on the seams. I got it to within a 1/4 bubble on my Starrett before the seam popped so maybe depending on how far off it is you can fix it without dis assembly but I am guessing no because of the screws holding the slate down.

 

[tjohnson]

I had the same issue with my GC, I set it up myself and just plain screwed up. I tried to raise the center without disassembling and I split a seam, I used Bondo on the seams. I got it to within a 1/4 bubble on my Starrett before the seam popped so maybe depending on how far off it is you can fix it without dis assembly but I am guessing no because of the screws holding the slate down.

Yeah, I can just imagine my guy pounding in a shim without loosening the slate screws and breaking the slates. I mean, you HAVE to take the cloth off and loosen the screws, right? Perhaps if the slates were nice flexible slate instead of inflexible Brunstone this could work...

 

[tjohnson]

I had the same issue with my GC, I set it up myself and just plain screwed up. I tried to raise the center without disassembling and I split a seam, I used Bondo on the seams. I got it to within a 1/4 bubble on my Starrett before the seam popped so maybe depending on how far off it is you can fix it without dis assembly but I am guessing no because of the screws holding the slate down.

fastone371, here are a couple of photos showing the unshimmed degree of tilt on my table. These are from the left and right cushions at the head of the table and you can see the amount of sag towards the middle. I know you were able to shim out some of your swayback. Was it this bad to begin with? Thanks!

 

[fastone371]

fastone371, here are a couple of photos showing the unshimmed degree of tilt on my table. These are from the left and right cushions at the head of the table and you can see the amount of sag towards the middle. I know you were able to shim out some of your swayback. Was it this bad to begin with? Thanks!

I would say mine was about 20% less out of level but I had no problem what so ever getting mine back in order. I suspect you will have no problem with yours either. The machinist levels are really sensitive, what looks alarmingly out of level at first really is not that far off, you would probably barely see that on a regular level.

 

[tjohnson]

I would say mine was about 20% less out of level but I had no problem what so ever getting mine back in order. I suspect you will have no problem with yours either. The machinist levels are really sensitive, what looks alarmingly out of level at first really is not that far off, you would probably barely see that on a regular level.

Thanks, that's very encouraging. My next challenge will be getting the mechanic to actually do what he needs to do to make it right. I'd actually prefer to do the leveling and seam finishing myself, but I don't trust myself to reinstall the cloth.

 

[realkingcobra]

Thanks, that's very encouraging. My next challenge will be getting the mechanic to actually do what he needs to do to make it right. I'd actually prefer to do the leveling and seam finishing myself, but I don't trust myself to reinstall the cloth.

If he had the skills needed, he'd have done ir right in the first place.

 

[tjohnson]

If he had the skills needed, he'd have done ir right in the first place.

So true....

 

[bradsh98]

Yeah, I can just imagine my guy pounding in a shim without loosening the slate screws and breaking the slates. I mean, you HAVE to take the cloth off and loosen the screws, right? Perhaps if the slates were nice flexible slate instead of inflexible Brunstone this could work...

I don't have a lot of experience with Brunstone, but I would think that you MAY be able to get some, if not all, of that sag out of it, without loosening the screws.

The screws are inserted at an angle, toward the center of the table. Being that the brunstone is sagging in the middle, raising the middle of the brunstone should apply outward pressure on the screws, thereby slightly lessening their compression force on the brunstone. Of course, this is theoretical, and the reality could prove to be a bit different, but I don't see too much harm in trying, so long as you don't exert too much force with the shims.

The placement of the shims may be critical, in keeping the seams from 'popping'. The best chance you have to prevent that, is to shim both sides of the seam evenly, at the same time. Since you'll be shimming along the support brace that extends the length of the table, I would suggest placing two opposing shims, one on top of the other, at roughly 30 degrees to the center support brace, directly below the seam. This will allow you to go back and forth, tapping the shims into place a little at a time, while raising both sides of the seam at the same time.

Perhaps RKC could give his opinion on this solution, as I know he has more experience with Brunstone.

 

[tjohnson]

I don't have a lot of experience with Brunstone, but I would think that you MAY be able to get some, if not all, of that sag out of it, without loosening the screws.

The screws are inserted at an angle, toward the center of the table. Being that the brunstone is sagging in the middle, raising the middle of the brunstone should apply outward pressure on the screws, thereby slightly lessening their compression force on the brunstone. Of course, this is theoretical, and the reality could prove to be a bit different, but I don't see too much harm in trying, so long as you don't exert too much force with the shims.

The placement of the shims may be critical, in keeping the seams from 'popping'. The best chance you have to prevent that, is to shim both sides of the seam evenly, at the same time. Since you'll be shimming along the support brace that extends the length of the table, I would suggest placing two opposing shims, one on top of the other, at roughly 30 degrees to the center support brace, directly below the seam. This will allow you to go back and forth, tapping the shims into place a little at a time, while raising both sides of the seam at the same time.

Perhaps RKC could give his opinion on this solution, as I know he has more experience with Brunstone.

Thanks for the response and an interesting suggestion. Leveling without having to remove the screws would be a beautiful thing...

 

[tjohnson]

So just checking to see if anyone knows for sure if you can shim without removing - or at least loosening - the slate screws. It seems to me that if they are screwed down tight, shimming would not accomplish much, especially with stiff/brittle Brunstone.

Table is covered and set up, just wondering how far back in the process I'll need to go to get the slates more level. I'm assuming it's at least rails off, cloth off, screws loosened.

Thanks in advance!

 

[tjohnson]

Got my answer from an expert! We'll see how it goes next week...

 

[n10spool]

Take the rails off and check for level again.

0. Double check level is leveled or adjust it.
1. If level you have warped rails.
2. If not level with rails off then relevel from the start.

 

[tjohnson]

Take the rails off and check for level again.

0. Double check level is leveled or adjust it.
1. If level you have warped rails.
2. If not level with rails off then relevel from the start.

Thanks for the suggestion. I'll definitely check the level once the rails are off.

 

[tjohnson]

Just wanted to post a follow-up on my experience. The mechanic came back and we worked together to level the slates. Ultimately got out about 95% of the swayback, which may not have been swayback as much as it was just a lack of shimming. We might have gotten more out, but I wanted to stop because I started to get nervous about cracking the Brunstone. Next recover, I'll go for 100%.

Pics show great improvement: