mini metal lathe -- tool post for woodturning

[Dr Stan]

It's not the motors that can be damaged, but the ways of the lathe. If you do use a tool post grinder on your lathe cover as much of the ways as possible WO creating a situation where the cover could be caught in the grinder. Afterward remove, clean & re-oil all the wipers and give the ways and cross slide a cleaning like none other.

[Toolmaker51]

mklotz wrote "One thing I've always wondered about...What, if any, are the dangers of lathe motors ingesting airborne metallic dust created during grinding? Many small lathes have the motor axis quite close to the spindle axis so, if they have a cooling fan, as I expect many do, they are all set to eat whatever dust is coming off the work. This could be an issue with sawdust as well".

Hadn't even considered motor ingesting grind dust. Commercial equipment normally are TEFC, and/or shrouded by castings immune to such dietary intake.
Never ground on a lathe, mill or non-grinding machine I've paid for. My floor plan provides a room enclosed and ventilated just for abrasive pieces of work.
Not including in-laws...

[pfredX1]

I have a mill that I've owned for over 25 years. I work on whatever with it. Wood, metal, plastic, I grind sometimes. Just clean and oil your machinery regularly and you'll be far ahead of what most production equipment is made to deal with. Tools are made to be used. Anyone that tries to tell you anything different is a fool. They'd all have heart attacks if I ever took them to E P Heller's shop. He works all in carbide. Someone's gotta. Talk about abrasive grit.

[ragsflh]

thank you for info

[kutzbill]

OK, I am a retired Toolmaker with 42 years in the shop. Here are a couple of thing to consider.
My favorite machine is the lathe, but it is by far the most dangerous machine in the shop. On industrial lathes you can be running high HP motors with very high torque, and they will wind up a shirt faster than you can blink. I don't mean to imply anyone is dumb, but I have seen some people that have 15 years in the shop and had their shirts tore right off, one time he was missing 2 fingers, and a broken arm, shoulder, and 2 cracked ribs. Another one was using a file without a handle and it ended up embedded in is arm wit just the last inch sticking out.
First off, keep your work as close to the jaws as possible. I used to cringe when I would see Adam off of Mythbusters have a piece of plastic hanging a foot away from the chuck.
Second, if you want to cut any type of plastic, use a really sharp tool, not an insert unless it is an insert specifically for turning plastic. Have a good sized radius on the tool, (IE 0.015"). A sharp point will give you a bad finish, and has a tendency to grab, sometimes breaking the work piece. A good rule of thumb is to set your feed the same size as the radius of the tool for rough-out, and just under the radius for the finish. If you get chatter, increase the feed.
Use an indicator to center your work. I have a 3" X 4" piece of brass I use to tap the work piece while it is running and that usually bets it in close enough to work. Remember if you measure 0.001" run out, you are in 0.0005 total OOR, (out of round).
Most 3 jaw chucks don't have the 3 set screws to center your work, so tapping them will get pretty close. With a 4 jaw chuck you have to indicate every piece, but a 4 jaw holds very tight.
I have used several tool post grinders, and they can (or rather the debris from the wheel) can mark up your ways. I used to use wet rags (water) to keep as much as I could from getting in the ways. Use a good way oil, and use extra (to flush) oil when grinding.
I personally have never had an issue with dust hurting the motors. Grinders have the same type of motors, and all they do is grind. Most motors have sealed bearings with the shields, so dust isn't an issue. I am not familiar with the type of lathe you have, but I doubt it has a large HP motor on it, but it can still be very dangerous.
Make sure you center the tooling. Usually just sighting the end while the work is turning, or if the tailstock is indicated in, use it.
I'd be happy to help any way I can. feel free to write.
Smiles,
Bill

[kngtek]

There is a good thread on this subject at (Non-TEFC motors, Metal & Wood dust?). Essentially metal grinder dust can, over time, cause shorting in open motors and additionally cause brush/commutator wear in universal or dc motors. On the other hand, wood dust will clog and eventually overheat (but not likely short out) open motors and can even clog the external fan housing of TEFC motors.

I don't have a tool post grinder, but suppose that those hobby machinists who do - have a lathe with a totally enclosed motor and sealed bearings.

Journal bearing-equipped machinery like my first Shop Smith woodworking machine (circa 1950) are also susceptible to airborne metal or ceramic dust - I stupidly jammed up the bearings cutting ceramic tile with a dry diamond blade many years ago and had to rebuild it. I didn't have a wet tile grinder at the time, but do now.

After this experience (now being gun shy) I moved my old Sears dry grinder into my garage workshop, away from my metal working shop in my house basement and purchased a Tormek wet grinder for drill, cutting bit and woodworking tool sharpening.

Gary (kngtek)
Calgary, AB

[mklotz]

Thanks for that, Gary. It's about what I expected but, lacking experience, didn't want to volunteer, hence the question.

I might point out here that the OP was talking about a 7 x 14 mini lathe. I expect that such a lathe and many of similar size will lack TEFC motors, hence my concern about grinding on such machines. OTOH, from what I've read, the motors will probably long outlast the electronic speed controls on these built-to-price imports even if used exclusively for grinding.

[whome]

Thanks for bringing that to our attention, I should have mentioned not to use just a single layer. I like rags for the top layer because grinding swarf does not bounce off, like it does on a smooth or hard surface. The rags provide a labyrinth to trap particles,and the oil is sticky, oil can not be used where sparks are generated, you don't want to start a fire. Unless the motor is totally enclosed, fan cooled, (TEFC), it must be protected, always including the shaft so nothing gets past the seals or into the bearings.