Table flatness

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HopefulSSer
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Table flatness

Post by HopefulSSer »

I was just watching a MGR video on setting the 90* stop of the table in drill press mode by using a sanding disc and feeler gauge. Clever way of doing it, but it wouldn’t work on mine (or at least no better than anything else I’ve tried*) because neither of my two 500 tables are flat. They’re both down a bit in the center, I presume from years of force from drilling.

I’ve very carefully put them in a hydraulic press and tried to push the middles back up but with only partial success. There’s a lot of springback and I’m afraid to press to far lest I crack the table. Given that 100% of the tables I’ve ever seen (n=2) have this problem, I presume it’s common. Is there a generally-accepted solution? I searched but came up empty handed…

Thanks!

(* I just try to average out the error)
Greenie SN 362819 (upgraded to 510), Bandsaw 106878, Jointer SS16466
bainin
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Re: Table flatness

Post by bainin »

I've never looked at mine that closely, though i do see table deflection when the drill comes into contact with the wood-more like radial deflection
from the mount point on the way tubes.

Is the deflected area that large ? I mean if your stock spans over the deflected area of the table, it may be a non issue.

b
HopefulSSer
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Re: Table flatness

Post by HopefulSSer »

For large pieces it's less a problem. For smaller one maybe it comes more into play. Mainly it's annoying when truing everything up because it introduces variability based on where I happen to measure. Thus having to try to average out the error.
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chapmanruss
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Re: Table flatness

Post by chapmanruss »

HopefulSSer,

Although I do not have any Mark 5 or Mark V 500 Shopsmith's at this time I do have two of the Main Tables. One is from a 1983 Mark V I restored that had damage and the other is an 1980's or later Main Table. The 1983 Main Table is flat, but the other Main Table is slightly bowed down in the center toward the insert opening as you described. What I find interesting looking at the two Main Table I have is the 1983 obviously was used in drill press mode as evidenced by the damage (see picture below) but is still flat.

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IMG_0040r.jpg
IMG_0040r.jpg (160.78 KiB) Viewed 1353 times
.
I have also restored and resold 2 Greenies and a Goldie but do not recall any bowing of the Main Tables on those.
Russ

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dusty
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Re: Table flatness

Post by dusty »

The question once again.

For our kind of woodworking (non-professional): "How flat is flat?" I have four tables (all 510/520) and they all exhibit some slight cupping in the center.

Were they milled that way or did I do something to bring it about? I'd bet they came out of the factory that way and that they would all pass "production testing".
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HopefulSSer
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Re: Table flatness

Post by HopefulSSer »

Here's the video that prompted my question:
https://youtu.be/L5mEVr_iO5E?t=215

As I mentioned in the OP, he's using a feeler gauge (in this case a slip of paper) to check that the 90º stop is set properly. So he's presumably detecting variance around 0.002-0.003". If the table is out of flat an order of magnitude more than that, the method obviously can't work.

For table-sawing, maybe it's not that big a deal. But if you're in drill press mode it might be more critical for what you're doing that the table be perfectly 90º to the quill in both directions. And if the part you're drilling is small then even if the table IS perpendicular you might still have a problem.

I suppose you could place some thick MDF or something on the table to bridge the waviness and gauge off that, but that doesn't address the small-part problem unless you also use it while drilling....
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dusty
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Re: Table flatness

Post by dusty »

HopefulSSer wrote: Sun Jan 01, 2023 8:08 am Here's the video that prompted my question:
https://youtu.be/L5mEVr_iO5E?t=215

As I mentioned in the OP, he's using a feeler gauge (in this case a slip of paper) to check that the 90º stop is set properly. So he's presumably detecting variance around 0.002-0.003". If the table is out of flat an order of magnitude more than that, the method obviously can't work.

For table-sawing, maybe it's not that big a deal. But if you're in drill press mode it might be more critical for what you're doing that the table be perfectly 90º to the quill in both directions. And if the part you're drilling is small then even if the table IS perpendicular you might still have a problem.

I suppose you could place some thick MDF or something on the table to bridge the waviness and gauge off that, but that doesn't address the small-part problem unless you also use it while drilling....
I don't believe the system is designed for that degree of precision. in the drill press mode or otherwise. If I was guaranteed accuracy to within a 32nd or 64th of an inch I would be tickled pink. Yes, I can tweak and tweak until I get there. But then I change modes and start all over again.

Bottom Line: If you want dead on precision - pay for it.
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HopefulSSer
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Re: Table flatness

Post by HopefulSSer »

dusty wrote: Sun Jan 01, 2023 11:06 am Bottom Line: If you want dead on precision - pay for it.
Certainly one approach, but why not make the most of what we have, and improve it where we can? Why settle?
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dusty
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Re: Table flatness

Post by dusty »

Agreed. Have at it.
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HopefulSSer
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Re: Table flatness

Post by HopefulSSer »

dusty wrote: Sun Jan 01, 2023 11:56 am Agreed. Have at it.
#thumbsup

So back to the original question then: Since this may be a common problem, is there a common fix?
Greenie SN 362819 (upgraded to 510), Bandsaw 106878, Jointer SS16466
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