Toolpost Needle Valve Grinder

[GWRdriver]

Brian,
I just now tuned in and had I arrived sooner would have reported that this scheme never worked for me. I have to qualify my statement by saying that what I wanted to achieve was a substitute toolpost grinder and even the best Dremel or Dremel-clone tools (specifically their bearings) aren't up to the job. The reason is just as you have discovered, there is too much flex and runout in the cheap spindle.

I'm not exactly sure what you need to accomplish - is this a shaping operation or a finishing operation? If it's a shaping (ie, turning) operation and what you need is increased spindle speed I would start to think in terms of an accessory spindle which would mount in your lathe spindle nose and be driven by a small high speed motor & belt.

Tell me more before I wander way off course.

 

[Lakc]

Indeed, tried myself and learned long ago. It was an interesting experiment, but now you know why they charge so much for machine tool grade bearings. Small rotary tools wont cut it for a precision application.
Now if you want to create a wide toolholder that can take perhaps 1.5" od bearings (tapered roller?), and make a custom spindle with a simple belt drive, it might be reasonably cheap and effective. That's "on my list" for a go eventually.

 

[Mike N]

I have thought many times about trying to make a grinder like that Brian. But mounting it always seems to be what changes my mind.. I saw this last time i was at HF, I started to buy it but didnt.. I think it could be mounted alot easier, but requires air instead of electricity..Bill
http://www.harborfreight.com/1-8-eighth-inch-air-micro-die-grinder-47869.html

I used this exact one from HF on the little toolpost grinder I made, it fits right into the Aloris style tool bit holder without any modification. I use diamond cutters instead of abrasive wheels that seem to bounce all over the place.

 

[Art K]

Hi Brian,
Just caught your needle valve grinder. That's a great idea, I wouldn't have thought of. I will keep it in mind next time I build a carb.
Art

 

[Brian Rupnow]

Hi Brian,
Just caught your needle valve grinder. That's a great idea, I wouldn't have thought of. I will keep it in mind next time I build a carb.
Art

Art K---You might want to re-read post 15.--Its a great idea but it didn't work.---Brian

 

[AUTO_XX]

I did one a couple of months ago to bore a 1/4" inside groove with an endmill 3/4 deep. There was a bit of chatter if I didn't get enough WD40 (handy for aluminum) but apart from that it worked great.
It's also a "must-have" item for polishing. You can bring a mirror finish up in just a few seconds.
The surface finish isn't as nice as turning with the lathe tooling but it was liveable.

 

[rayjones]

Nice work Brian. I have a 3/8 Hitachi battery drill (drill in good condition, batteries expired). I also have a DC power supply which
will power the drill. With not too much work, I will have a tool post drill.

Regards Ray Jones

 

[Brian Rupnow]

So----Today I'm in time killing mode. The toolpost grinder that I tried to make by holding the Dremel tool in a wooden block was a dismal failure. Oh well, it didn't cost me anything, and nothing was hurt but my pride. Today I took the time to make a metal holder for my much sturdier all metal ARO air grinder. It works.---At least it doesn't jump and wiggle around when used----Its very sturdy. I realize that there is an entire world of things I don't know about grinding in a lathe. I do know its not good for the ways, so they should be protected when doing this. I know there are proper mounted point style stones (all I have today is that cheesy cut off wheel in the pictures) and that they should always be trued with a diamond? or something before each use. I have a lot of reading to do, to study up on this entire business. There is nothing in particular that I want to grind---except maybe the pilot on all of my counterbore tools.--They are always much larger than the holes I generally use for clearance holes when model building. --Perhaps if I ever get bold enough to build another i.c. engine, I could grind the valve faces. Oh well, I've killed half a day, and that's what this was about as much as anything.---Brian

 

[Lakc]

Wtg Brian. Give it some more testing and let us know how well it works.
My thoughts have returned to this idea as well, as I have a cast iron crankshaft that is a little chilled and too hard, and I could use any old grinder type setup to just get past the skin on it.