Tool Post Grinder

E

EarlH

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This post is not about the horrors of using a tool post grinder so please spare me the advise about not using it. I am interested in how to effectively use one. I have one that came with my lathe. The previous owner of the lathe bought it used and sent it back to Dumore and had it rebuilt. It is a very small grinder- quarter hp. The label says it turns 16,000 rpm. I don't think that it has ever been used since being rebuilt. It appears that the arbor is brand new, the pulleys look new and I took the new belt out of a sealed plastic bag and put it on the unit. I really don't know if I will ever use it or not but I would like to know how. I am interested in knowing what speeds to turn the stock being ground. I believe that I want the stock turning the opposite direction that the grinder is running. How deep a cut should I be able to take with a small unit like this.

Any and all information about tool post grinding is welcome.

Earl
 
Dumore makes good quality tools. Should you decide you're not going to use it, and want to sell it, please let me know. I've used a TPG a bit, so I'll try to answer your questions.

As far as stock feed, it doesn't make a lot of difference, but slower speeds tend to heat up the work a little faster if you're running dry.

Stock direction makes no difference, save for this: Just like in milling, climbing is preferable if you can do it. Wheel wear will be slightly better running with the spindle opposing the grinder, but will cut faster running with it. The only effect on cutting speed is slight. You either add or subtract the sfm to the grinder, which is already so much faster than the spindle, percentage wise, it's insignificant.

DOC is dependent on material and wheel selection. TPGs aren't hogs, so don't expect fast material removal. A few thousandths at a time, like .001/002 max. The less the better, for a few reasons. Remember too, that to speed up a grinder like that, you sacrifice hp.
 
Thanks for the information. Now I will have to install it and give it a try. The previous owner of the lathe and grinder (a friend) had intended to use it to grind punches for bullet making. The lathe is a heavy 10 and has had the headstock bearings replaced and a new, ground lead screw installed but I doubt that it could hold the tolerances required for grinding seating punches. My punch set includes punches that are two tenths apart. I'm not sure that I could even measure them accurately. The Newall DRO on the lathe reads to the tenth but pulling / pushing on the cross slide shows the wear in the cross slide screw/nut.

Earl
 
Earl

I would start by going to Dumores website http://www.dumorecorp.com/grinder.htm and downloading the instruction manuals for your grinder. There is also a yahoo group subscribe-DoMoreWithDumore@yahoogroups.com that has some of the manuals ofr older ones in the files section.

As for the manuals, even if you do not find the exact one, they all have similar info as for the usage. I downloaded and printed most of them off for the odd time I need to dig out my Dumore #44

Walter
 
Went to the Dumore web site and got the manual for my series 14 grinder. Looks like the wheel guard is missing as well as the belt guard. At about 16,000 rpms, that wheel appears to be dangerous. Talked to the previous owner and he told me that he never opened the box when he got it back from Dumore. I guess I will call and order a guard. There is a couple of small stones and a mandrel that will fit the spindle so this thing will do both inside and outside grinding. It will only support about a two inch wheel for outside grinding. What type of coolant should be used with this?

Earl
 
Most of the older Dumore grinders did not come with guards of any sort. My #44 did not even have the hole drilled for the belt guard. I did order the guard from Dumore for the newer model then drilled and tapped the appropriate hole to mount it.

Was not sure I wanted my pinkies that close to a whirling belt without a guard on it.

Walter
 
Good idea, Walt! Some 40 years ago, while I was in school, and working nights at Cargill, I did get a pinky too close to an arrangement just like the end of your grinder. Wham! Wrapped it through that pulley and cut it damn near to the bone. Owww...
 
Of course, by their nature, grinders are hazardous. I always ring my wheels before mounting them, and always stay out of line. I worked with an excellent T & C man years ago, who I thought had the experience to know all there was to know about safe grinding. He had a wheel blow up and a piece shattered his glasses and took out his right eye.

Pay attention! There are RPM warnings on wheels that are for your own good. The thing about TPG's is that it is quite easy to overspeed a wheel. They can do 40-50k with a 1/4" mounted stone just fine, and that is obviously way too fast for a 4" wheel, for instance. Read and heed!
 
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