Powerpro in a Mark VII?

[sheldonp]

I know it's been talked about, but has anyone actually attempted a Powerpro conversion on a Mark VII? I'm relativley sure you could make it work, but you might lose a couple of features. Judging from the photos I've seen, my main concern would be clearances between the gear rack mechanism and the motor mount, as well as the table/headstock interlock rod. I could live without the interlock. No gear rack would be a deal breaker for me, though. Thoughts? Insight?

[chapmanruss]

The Mark V headstock will fit on the old Mark VII, but you have to remove the gear rack. Sorry that is the best answer I can give you. I have not owned a Mark VII only seen them so I cannot compare Headstocks side by side to know.

[sheldonp]

I know the headstocks are basically interchangeable, and the dimensions are the same where it counts internally. The motor pan is actually a little deeper, at least in comparison to my Mark 5. I did notice while researching photos and videos that the motor mount for the Powerpro butts right up next to where the headstock lock/crank mechanism are on a Mark VII. The interlock rod that runs through the middle of the headstock looks iffy for clearance over the top of the motor as well. I use my Mark VII waaaaaaaaay more than my Mark 5 and don't really need the increased speed or power for most of what I do, but it would be nice to have a Mark VII that I didn't have to worry about running for extended periods or finding parts if I had an issue. I suppose I need to actually measure clearances inside the Mark VII and see if I can find a Powerpro nearby that I can check out internally.

[sheldonp]

As an aside, I've also considered just getting the Striatech DVR motor with their controller, the appropriate new double bearing quill, pulleys, etc and doing my own conversion. It'd be a heck of a lot cheaper than the upgrade kit for a mod that may or may not work
...

[JPG]

The non-obvious picky detail is the different spacing of the motor shaft to the idler shaft. The MVII is further away from the idler shaft which means the PP would need to be mounted higher than a mVII motor. Then there is the idler shaft / eccentric difference as well. At the very least a new motor mount would need to be designed.

Then there is the loss of the vacuum.

[sheldonp]

I hadn’t thought about the idler shaft. Good point. That would definitely need a work around. The loss of the vac doesn’t really concern me as I don’t use it at all.

[sheldonp]

I'm not afraid of doing modification or machine work to get the conversion done. I spent enough years in machine shops working on other people's bright ideas that I'm confident I could measure everything properly, make the motor mount, etc, etc. My thought was to find a derelict Mark VII (or a headstock, tubes and caps that I could build a heavier base for - I see them fairly regularly around here pretty cheap) and use it for a guinea pig. I appreciate any and all input on things to look out for, what-ifs, etc.

[everettdavis]

I think JPG or someone built a Frankensmith using a Mark VII headstock and dropped in a Mark V motor and motor pan that bolted right up on the bottom end. He adapted the speed control and pork chop from a Mark V if I recall. I don't have the thread available on the phone.

That would accomodate the motor mount in the pan piece for DVR motor and bracket.

He discussed some of the measurements and differences inside. That might prove useful. Also the DIY upgrade would have all the components.

I think the issue will be the Drive Sleeve.

Also look at my Shopsmith Bearings Gude for photos on all the various. Pieces in the headstock where I discuss the Drive Sleeve Assemblies.

Everett

[everettdavis]

I think there was an alignment offset on the motor to drive sleeve that you might could resolve with offset mounting holes for DVR motor to correct for it.

Look at the DIY upgrade video for more insight.

Everett

[JPG]

I think JPG or someone built a Frankensmith using a Mark VII headstock and dropped in a Mark V motor and motor pan that bolted right up on the bottom end. He adapted the speed control and pork chop from a Mark V if I recall. I don't have the thread available on the phone.

That would accomodate the motor mount in the pan piece for DVR motor and bracket.

He discussed some of the measurements and differences inside. That might prove useful. Also the DIY upgrade would have all the components.

I think the issue will be the Drive Sleeve.

Also look at my Shopsmith Bearings Gude for photos on all the various. Pieces in the headstock where I discuss the Drive Sleeve Assemblies.

Everett

Not I, but I did show the motor pans are very close at the top.