I stripped the T-nuts on my PM-1030V compound

It looks like the compound is only making contact on a small ring vs. the entire bottom surface. This will greatly reduce the holding strength. Can we get a picture of the bottom of the compound?
 
macardoso said:
It looks like the compound is only making contact on a small ring vs. the entire bottom surface. This will greatly reduce the holding strength. Can we get a picture of the bottom of the compound?
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You bet. As you can see, you would only want the circular bottom to touch the top of the cross slide. If the plate (or "bezel") that clamps down the circular base were to contact the top of the cross slide, the compound would be free to move.

As one can imagine, the angle of the compound is changed by loosening the T-nut hardware in order to allow the compound to rotate. Once in the desired position, the operator tightens the hardware so as to clamp the circular base firmly to the top of the cross slide.

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Here is the assembly with the plate clamping down the compound. I am waiting on 8mm T slot nuts.

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One possibilty is that I tightened the nuts so much that the clamping plate did contact the top of the cross slide. This would have the effect of introducing additional clamping surface area (on both top and bottom), thereby reducing the amount of clamping pressure in the area where it is intended to be. After all, there is only so much clamping pressure provided by the two bolts.

I don't believe that there is anything to be gained by the clamping plate coming in contact with the (top of the) cross slide.
 
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My 10-30 has the same compound mounting system as yours. I thought about SHCS and T nuts, but can't see how I'd tighten them with a shallow angle on the compound. My solution will be to open the hoes to .378 or so, and make screws similar to the originals from ETD150. I have some .920 in diameter, long enough to make two. I'll find some hard 3/8 24 nuts and shorten them so they fit.
 
T Bredehoft said:
...screws similar to the originals from ETD150. I have some .920 in diameter...
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Do you mean .920" in length?

I could not find a picture of these in Google image. Can you post a picture, please?

I also thought about opening up those holes for either an M10 or 3/8" bolt.

The 3/8" studs commonly used for T slot nuts are 16 tpi. As you know, 16 tpi is coarse and 24 tpi is fine, both of which are easily sourced in Grade 8.

I wonder if fine threads would provide an advantage over coarse in this application.
 
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Weird... I've never seen that system. I would consider taking apart the compound assembly and make sure the surfaces are clean of oil. This will probably help increase your clamping.
 
macardoso said:
Weird... I've never seen that system. I would consider taking apart the compound assembly and make sure the surfaces are clean of oil. This will probably help increase your clamping.
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In fact, there was a layer of way oil on both surfaces when this occurred. You would think I was trying to lubricate it. Of course, I was just trying to prevent pitting.

Another way to avoid the issue would be to make sure that I had a sharp cutting tool, shallow cuts, cutting fluid (certainly for steel) and proper feeds and speeds.
 
Rough up the two surfaces after making sure there is full contact. Bead or sand blast like surface will help.
Pierre
 
looks like a 9x20 style 4 bolt mod would be a good idea. Probably find some plans on Steve Bedair's website.
 
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