PM 833T Table Locks

[Bill Kirkley]

I could never get the Y axis table lock wing bolts to tighten. I replaced them with 3/8-16 bolts and use a 1/4" drive ratchet with an extension. It does a much better job. I also replaced the X axis levers with longer ones.

It's odd that the X axis is metric and the Y axis is SAE standard.

 

[Long Roof]

I have had the same issues with the Y axis but you are quicker with a fix than I am. I would have never guessed SAE threads. I will be sure to check mine before I make any changes. I do like your solution.
Thanks for posting.

 

[petertha]

That seems a bit odd to me that its not locking properly with hand tightening. If its like most of the Asian machines, the threaded stud is acting on the gib strip which is then acting on the dovetail. When I removed the gib strip for my 14x40 lathe it had a series of little semi circular bite marks all down the strip. I think wrenching it would be even worse.

On my RF-45 mill, somewhat similar to yours, after DRO installation I could see there was always a bit of drift by the torque action of tightening. So I made a short brass shoe to match the 60-deg dovetail & a bearing ball on the stud end so there was no secondary displacement effects, just pure axial clamping action into the dovetail. I didn't do this with my 935 mill because it just stays put & DRO drift in the tenths, so I assumed just a better clamping arrangement although it looks like the same old stud method.

Not saying what you are doing is wrong, but might be worth a call into PM if there is some other reason.

 

[Bill Kirkley]

Long Roof, if you try it out I'd be interested in how it works for you.

Petertha, the end if the wing bolt was ridged like a typical bolt. I ground it flat. Hopefully that will prevent gouging. A big problem with the wing bolts is that the wing is small and they are awkward to get to, making it difficult to tighten. Also, at 70+ years, my hands aren't as strong as they once were.

 

[Long Roof]

I can see the problem with possible over tightening. My biggest issue is that my index fingers don't work like they used to. It is difficult for me to get them into the tight space and get much leverage on the factory knob. I need at least an extension so I can get a better grip.

 

[Bill Kirkley]

I changed out the bolts for a 5" long bolt in the back and a 3 1/2" long bolt in the front. I got one of those ratchet wrenches you flip to loosen or tighten.

Now I can reach under the table to loosen or tighten the table lock without having to bend over.

 

[Bill Kirkley]

That seems a bit odd to me that its not locking properly with hand tightening. If its like most of the Asian machines, the threaded stud is acting on the gib strip which is then acting on the dovetail. When I removed the gib strip for my 14x40 lathe it had a series of little semi circular bite marks all down the strip. I think wrenching it would be even worse.

On my RF-45 mill, somewhat similar to yours, after DRO installation I could see there was always a bit of drift by the torque action of tightening. So I made a short brass shoe to match the 60-deg dovetail & a bearing ball on the stud end so there was no secondary displacement effects, just pure axial clamping action into the dovetail. I didn't do this with my 935 mill because it just stays put & DRO drift in the tenths, so I assumed just a better clamping arrangement although it looks like the same old stud method.

Not saying what you are doing is wrong, but might be worth a call into PM if there is some other reason.

I checked the DRO with tightening the bolts. The table shifted 5 ten thousands. That is ok for the work I do.

 

[Bill Kirkley]

I found out the hard way why they used short handled clamp levers (part 10) for the X-axis. My long handled lever caught in the mill's base and bent!

I replaced all four clamp levers with M8X50mm bolts. I ground the end of the bolts smooth. It works great!