Some time ago I posed a question about fit for needle roller thrust bearings. I got very useful info, and my intended target was this light duty live center with exchangeable tips.
It was in this thread:
http://madmodder.net/index.php?topic=7054.0So at last, a day when I could get into the shop to continue with the light duty live center, my version with exchangeable tips. The idea originally came from the book about Unimat 3 lathe accessories by Bob Loader. I made the accessories for my MJ-189 (which I stll have) and found them to be very useful every so often. So useful that I wanted the same stuff for my C3.
But as in many cases you have to make something else to be able to start on what you had in mind ...
So I had to make a drawbar for the lathe to be sure that the MK tooling in the spindel stayed there. A drawbar is nothing complicated, it only takes some time, and out of the machine came the following contraption.
A brass bar with an M10x1.5 thread in one end, and an M12x1 thread in the other. The M10 end was for the MK tooling end. As a "nut" I made a sleeve with a close fit in the spindel in one end, supported by a shoulder to act as a stop when tightening, and a handwheel in the other end. All made from brass bits form the scrap box.
The C3 have an MT3 taper in the spindle and as the item I made would have an MT2 for the tailstock I used an MT3 to MT2 sleeve with a nut. This nut makes it possible to release both the MT2 part from the sleeve and sleeve itself from the spindle without having to bang in the axial direction, something I avoid to keep the bearings in shape.
The whole setup looks something like this when out from the lathe. Actually very good and solid during work.
The handle end is made so that the end cover can be kept in place during work. It becomes much tidier then.
OK, so now it is possible to start with the real job. I used a ready-made blank end arbor as I have not made myself a taper turning attachment yet. As can be seen, I took down the outer diameter fom 40 mm to about 30mm and then made a hole for the needle roller thrust bearing I had (21x4x8 mm).
The hole was made 25 mm deep, the bearing used 4 so the plain bearing sleeve to in to the hole should be 20 mm deep to avoid locking the bearing. Still the outer bearing ring missing in the picture.
The sleeve has a small shoulder and is made to a close but still easy and wggle-free fit in the housing. When all parts were assembled I drilled a crosshole through the housing and the bearing sleeve to lock them together but still be easy to take apart if needed.
I also drilled a small oil-hole through the securing screw which can be seen from the picture in the tailstock.
Then I made some different ends to fit, but the one I show here is the tip that I use to fit my small drillchuck etc.
This tip mimics the MJ-189/Unimat 3/4 spindle nose on one end and has the 12 mm dia end for the center in the other. Using this tip I can fit different tools from my MJ-189 machine range such as drill chuck ...
... or a small 55 mm diameter scroll chuck, ...
... or a 60 mm 4-jaw, ....
... or a face plate that can have anything fastened to it.
The other tips are:
- A small male center allowing the turning tools to get very close to the end of the work.
- A female center for supporting thin bars without havin to centerdrill the end.
- A large diameter pipe center.
- A larger diameter flat pushplate used for example for thread finishing using dies.
Well thatīs about it. Another useful addition to the C3 tool box, and also widening the use of the parts for the MJ-189 at the same time.
Thanks for watching
BR
/Peter
