Hmade Toolpost Grinder

[CJ5Dave]

I need a toolpost grinder to true up the jaws in my ancient 3 jaw chuck. Kinda a low budget deal. Anybody ever made one out of a wood router? Got a donor with a broken base. Wondering what stone to use. The stones I have are rated 22,000 RPM. My router is rated 25,000 RPM. Not hardly enough reach except with an extra long shank stone.

 

[Chipper5783]

Follow Robin Renzett’s lead - hard turn it. That is what I intend on my tired 3J. A CBN insert of Aliexpress cost me $7.50CAD. The challenge will be sorting out the jaw loading method.

 

[pontiac428]

Routers are well built and should be good, the problem I see is the surface speed is over 3000 FPM. If you could, run a rheostat to slow it down. Truing a chuck involves carefully removing a couple thou at most, if it is rigidly mounted I think you get the results you are after. I've only done it with a tool post grinder, much slower turning. Still, I see no reason it wouldn't work.

 

[benmychree]

I had a tool post grinder that was made for OD grinding, direct drive at about 1750 RPM, it came with a screw on ID spindle, I put an approx. 1" diameter internal grinding stone on it, and tried to true up my chuck jaws; it made hardly any sparks, it did not chatter as is common with internal grinding, and it did an excellent job of truing up the jaws; this is to say you don't necessarily need high speeds to do internal grinding. High speeds make a stone act harder, and then they are prone to glaze over and chatter, lower speeds cause the wheel to act softer, where they self dress which counters the tendency to chatter. Bottom line it worked quite well.

 

[markba633csi]

The lathe needs to turn at very low speed, around 10 rpm if you can manage it. I've seen it done with a Dremel tool so it is doable
The jaws need to be blocked such that they are under tension as if they are holding a workpiece

 

[Headhunter Pipe Co]