Dumore tool post grinder adapted to use Sioux valve seat grinding stones

[gerritv]

Its a 11-011, not a 31. But in great looking condition. Manual and other parts info is in an earlier post in this thread..

For straight grinding the centre height doesn't matter much, for taper grinding I think you end up with a not-straight surface, I recall making that mistake once when truing up an ER11 collet chuck.

 

[DPittman]

That's right. I used shims to get the TPG spindle on center with the lathe spindleView attachment 27551View attachment 27552View attachment 27553View attachment 27554

Would a TPG loose functionality if it could not pivot on top of the compound and was instead fixed in one position on the compound?

 

[Darren]

Its a 11-011, not a 31. But in great looking condition. Manual and other parts info is in an earlier post in this thread..

For straight grinding the centre height doesn't matter much, for taper grinding I think you end up with a not-straight surface, I recall making that mistake once when truing up an ER11 collet chuck.

I thought it was 11, but its hard to see clearly. Thanks.

For taper grinding the two spindle centerline would have to be on the same level plane to avoid introducing an error. Same as when indicating a taper.

 

[Susquatch]

I'm not sure if there would be a problem running the TPG spindle at a different height that the lathe. The instruction manuals I read on the Dumore site all say they must be the same height. I suspect the TPG bracket that sits on the compound is designed to be loaded 90 degrees to the compound mounting stud. If the TPG is above or below center the loading would be diagonal and the bracket is not very robust.

The inside out toothed belt tracks perfectly and runs very smooth. In the last week I have run it about 10 hours and have not had a single issue with slipping, tracking or vibration. I think I will attempt to copy the belt guard used on later models as it would be a disaster to get fingers into the belt area when running.

In hind sight, I think high could be a fiasco waiting to happen if either drive stalled or the stone grabbed. On the other hand, low should work fine. But all assessed in my head so definitely not advice to anyone else. Just my curiosity and challenging assumptions at work again.

Glad the belt is working for you. I'm prolly just biased by the number of automotive timing belts I've seen that failed from the outside in. In fact, now that I think about it, that's how the timing belt on my Hartford Mill was failing. I kept it as a backup - no comments from the peanut gallery..... When I get back to the shop, I'll post a photo.

 

[Susquatch]

I thought it was 11, but its hard to see clearly. Thanks.

For taper grinding the two spindle centerline would have to be on the same level plane to avoid introducing an error. Same as when indicating a taper.

Agreed. Not sure I'll ever grind a taper though.

 

[John Conroy]

Would a TPG loose functionality if it could not pivot on top of the compound and was instead fixed in one position on the compound?

It needs to be able to pivot in order to be versatile. When I did the grinding on the 12" round plate I had to experiment with the angle so I would be able to traverse the entire face of the plate with the available cross slide travel on my lathe. Once that angle was determined I trued the stone face to be parallel to the plate using a diamond point.

 

[Darren]

Agreed. Not sure I'll ever grind a taper though.

It would be nice for making batches of R8 tooling for example. Once you fine tune the taper you could grind a bunched of roughed in parts at once between centers. Last one I did with just the lathe was a bit of a challenge to get the taper just right.

 

[PeterT]

In hind sight, I think high could be a fiasco waiting to happen if either drive stalled or the stone grabbed. On the other hand, low should work fine. But all assessed in my head so definitely not advice to anyone else. Just my curiosity and challenging assumptions at work again.

Generally the TPGs only have one motor direction dictated by the arbor threads. But sometimes one may find himself on the other side of spindle maybe depending on reach or angle orientation. The lathe can be reversed to oppose the grinder ok, but if you consciously positioned the grinding wheel high or low for some reason, this reorientation without confirming center height might be an example situation of bad things happening if the stone tried to walk up the part.

 

[Susquatch]

Generally the TPGs only have one motor direction dictated by the arbor threads. But sometimes one may find himself on the other side of spindle maybe depending on reach or angle orientation. The lathe can be reversed to oppose the grinder ok, but if you consciously positioned the grinding wheel high or low for some reason, this reorientation without confirming center height might be an example situation of bad things happening if the stone tried to walk up the part.

Yup, my thinking exactly.

 

[John Conroy]

I received the belts I ordered from The Belt Shop in Edmonton. I talked to Myron there and gave him the width and length supplied by Gerrit and told him it was for a Dumore tool post grinder. I hadn't yet seen the belt that Rudy posted but the belts he supplied are the same type. They are thinner and more pliable than the old belt.

 

[trlvn]

I received the belts I ordered from The Belt Shop in Edmonton. I talked to Myron there and gave him the width and length supplied by Gerrit and told him it was for a Dumore tool post grinder.

If you don't mind, how much did they charge? Was it a long turnaround?

I need a belt for the old Tom Thumb grinder if I ever get around to restoring it.

Craig

 

[John Conroy]

They were $22 each. I bought 3, more than a lifetime supply I'm sure.