Themac tool post grinder

[combustable herbage]

I was fortunate enough to pick up this tool post grinder, its a CJ40 it has the 3 spindles small grind wheel, large grind wheel and 6.43mm chuck, we spun it up briefly and it sounded a bit sluggish but we were out in a shed but $150 later it was mine I gave it a quick start at home it seemed better so maybe their power was poor but I want to give everything a good going over and proper lubrication before running it up for any length of time. Looks like they are still able to supply parts if I need anything. I am pretty stoked I think it has a lot of potential and I am close to finishing one project so this one will move into the queue this winter. From what I can see it looks pretty complete just need some grinding wheels a bit of hardware and and a few pulleys for speed changes.

 

[Susquatch]

How do you mount that on your tool post?

 

[trlvn]

$150? You suck!

Craig

 

[PeterT]

That's a great price even of you have to piecemeal parts. I hope the bearings in the spindle cartridge are in good shape, that's the heart of the machine & where the $$ occurs.

Themac is still around & so is the J40 model. I've spoken to them a few times. You may not like the price of new parts though. If you disassemble, try & get familiar beforehand with what's involved regarding bearings, resetting, oil....

Themac | Tool Post Grinders | Lathe Grinders

Themac tool post grinders have been made in the USA for over 80 years. An essential tool for precision grinding that is portable and durable.

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Tool Post Grinders | Order a Themac Grinder

Themac offers a variety of portable tool post grinders for sale to perform precision internal (ID) or external (OD) grinding jobs. Dependable performance since 1936.

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You can mount TPG on top of the compound as its usually done. Probably the biggest reason/advantage is you can set the compound to a shallow angle & therefore your net in-feed is much finer increment. Hint compound angle set at 5.7 deg yields a tenth (0.0001") infeed for each 0.001" line increment of compound. (But remember diameter reduction is 2 x 0.0001" so 0.0002").

Or if you have T slots on the rear of your sliding table, you can mount there. This isn't done as often but may offer advantages as the compound assembly can contribute to finish/accuracy issues depending on the lathe. In this regard the Themac design is versatile in that the spindle cartridge can rotate up/down the circular tee slots to different vertical positions.

 

[combustable herbage]

Well Craig this really sucks more, the thing is basically bolt on there is an opening and the bolt has holes to use a pin to tighten with a nut that will have to be machined to hold it in, the unit is really balanced especially on the compound. When I went there she had it in the shed cause it had power and it was advertised with 2 spindles, so she asked if I wanted to look at the other stuff it was an auction lot and I had looked at the other items online and there wasn't anything I was really interested in but I went for a look and she saw the other spindle and threw it in and then I bought some air cylinders but I was really glad I went for a look cause we found that spindle. So I will have to mill a new nut for it and now I will be able to as I purchased a king pdm-30 today and I am picking it up in 10 days.

 

[PeterT]

Pic-1: The conventional mounting arrangement presumes a T plate in the compound very similar to typical tool post plate. It has a threaded hole to match the clamping part you show with the radial holes. Yes you use a tommy bar rod to tighten. But looks like your cross slide does not have this T plate feature, so will require a workaround.

Pic-2: my idea to table mount the TPG by making adapter plate with same motor housing bolt pattern & then fasten plate to table T-slots.

Pic-3: water cut stones from 1/4" surface grinder wheel.

Pic 4,5: portable dressing tool fixture