Proccess of making a new chuck backplate

That lathe looks identical to a PM1127VF. I had originally ordered one these before changing my mind to get the 1236. Assuming that lathe is built to spec similar to the PM version, before the large bore model was available, the PM1127VF had a DIN 55021 spindle mount. This lathe does not have a cam lock or threaded spindle. It's basically the same type of spindle found on most mini lathes except the the DIN 55021 has a nose taper instead of a raised boss. Either the chuck adapter bolts onto the spindle using SHCS from behind the spindle or the chuck adapter has studs installed which again mounts on the back of the spindle with nuts. More details on chuck mounting with these types of spindle here.


Here's a photo of the spindle on my old mini lathe which is similar:
Img_0622.jpg



I hated changing chucks on that lathe. The back of the spindle has counterbores for the SHCS to sit in. Space was tight & it required a shortened hex key to loosen the SHCSs, it was a slow process.

PM's site no longer lists the spindle as a DIN 55021. I assume it has to do with when the large bore model was released. I hear the PM1127VF no longer uses the DIN 55021 spindle but mounting is still essentially the same, just doesn't have a taper for the nose anymore. I think someone called it a C3 mount like on their 10x models but I'm not sure if that's actually true. I can't find any specs on a C3 type spindle.

In relation to the OP's question, if your spindle is similar, the mounting bolt pattern is not critical as the boss/register (or if you have a nose taper) is what you would rely on to locate the chuck adapter. The bolts just keep it attached to the spindle. You could make a short transfer puch & try to get enough of a mark on the adapter you make to indicate the holes. When I made an adapter for my mini lathe I ran into the same issue & did not have a mill. There was so little room I improvised my putting double sided tape on the spindle holes & pressed the adapter on to it to leave an impression of the holes. It managed to work out fine for me. Photo

Img_0622.jpg
 
That is excactly the kind of spindle I have. I managed to get a few photos along the weekend.

DSC_0106.JPG
DSC_0113.JPG
DSC_0117.JPG

This is the original 3-jaw
DSC_0109.JPG


This is the new chuck next to the original.
DSC_0129.JPG

For starters I can use the 4-jaw chuck and rough the backplate out.
Oh and as far as I can see, there seems to be no taper to any part of the spindle.

DSC_0106.JPG DSC_0113.JPG DSC_0117.JPG DSC_0109.JPG DSC_0129.JPG
 
I sure am glad Will (darkzero) came to the rescue on this as I sure was stumped. I've never seen this type of setup...

Sounds like you're on your way now...


Ray
 
Now I just have two more question.
Does the thickness of the backplate matter much?
I mean I could get same thickness material or slightly thicker.

And secondly is there some kind of way to smooth the start of the machine?
It has a belt driven pulley system and no clutch. Also no variator.
I just want that the starting of the machine would put less stress on the motor and household powergrid.
 
Within reason, thickness of the plate should not matter. If the bolts have enough stock to thread into that is all you're concerned with.

What is the power service in your home (i.e. 120 or 220, 50 or 60 Hz) and what are the electrical specifications of the motor? I am assuming it is a single phase and not 3 phase motor.

Depending on your household power service in your home and depending on the motor, you might be able to rewire the motor (assuming you're not already on 220 volt system).

There is no good way (that I know of) to give a single phase motor a "soft-start" or "ramp-start" capability that is economical/practical.

Ray



Now I just have two more question.
Does the thickness of the backplate matter much?
I mean I could get same thickness material or slightly thicker.

And secondly is there some kind of way to smooth the start of the machine?
It has a belt driven pulley system and no clutch. Also no variator.
I just want that the starting of the machine would put less stress on the motor and household powergrid.
 
Most of Europe is on 220 volt. So am I. The machine has a 220v motor and power rating is 1.1kW.
I don't know if it is 50 or 60Hz. At home I know that I've got max of 16A relays for 220v and 20A relays for the industrial 380v.
The industrial grid is 3 phase. That is pretty much everything I know about electrics at home.
 
OK...

My guess is that the motor is already wired for 220v and thus, it will draw the least amount of Amps already. What problem do you have with the motor? Is it blowing-out the circuit breakers or making the lights in the rest of the house flicker?

Your motor should only be drawing 5 amps so, a 16A breaker should be fine unless there are many other things connected to that circuit or, if the wire is not a heavy gauge.



Most of Europe is on 220 volt. So am I. The machine has a 220v motor and power rating is 1.1kW.
I don't know if it is 50 or 60Hz. At home I know that I've got max of 16A relays for 220v and 20A relays for the industrial 380v.
The industrial grid is 3 phase. That is pretty much everything I know about electrics at home.
 
No problems. I just wanted to make sure I wasn't overloading the motor due to toe bigger chuck and possibly a thicker backplate.
The original is 160mm and new 4-jaw is 200mm.
I don't want to mess the motor up.
 
Ah, there will be no problem with that. The extra mass of larger chuck is a theoretical nuisance but not a significant practical one. If that were not the case, imagine the problems we would have every time we worked on a 0.75 meter shaft of 10-12cm diameter... The world would end -but it doesn't.


Ray


No problems. I just wanted to make sure I wasn't overloading the motor due to toe bigger chuck and possibly a thicker backplate.
The original is 160mm and new 4-jaw is 200mm.
I don't want to mess the motor up.
 
Ok. Thanks for the info.
If I have any other questions about making the plate, I'll ask.
But I wont have enough free time to make it or get the material.
We'll see what next month brings.
 
Back
Top