One of the biggest returns for your $$$ for your mini lathe. Adding ball and thrust bearings to your tail stock.

[RaisedByWolves]

What if I told you a $10 outlay would make drilling on your mini lathe much more enjoyable and easier?

Lets face it, drilling on these is not the most pleasurable task compared to larger machines. You're fighting friction on all fronts and really have to manhandle the quill feed wheel to drill anything over an 3/16" (5MM for you metric guys), this can change that.



First you're going to have to look over your tail stock quill screw bearing plate. In the pic below its the part between the bearings and the tailstock handwheel. This is a simple and crude in most cases, plain bearing end cap for your tail stock.

I looked mine over and found a 10mm ball bearing and 18mm thrust bearing would fit the bill. Ordered them from the amazonians for about $10.


They look like this.

Now depending on your lathe and the shape of the quill screw bearing plate you may need to use a 4 jaw chuck like I did on this one (PraziSD400), or just a 3 jaw like I did on the last one I did (Prazi SD300). You will also need a saddle stop on your lathe to make hitting the proper depth east and repeatable.


You will need to bore two steps into the bearing plate, a precise bore for the radial bearing, and a clearance bore for the thrust bearing, where only the depth matters. The bore for the radial bearing needs to be a precise sliding fit, and it needs to be done first.


I used a Starrett snap gage to measure the bore as calipers wont give you as precise a measurement for several reasons I wont go into here.

Here's this step completed. Just sneak up on the final dimension and try to get as best a final finish as you can. The process of boring this hole will let you work out getting a good finish.

With that done I bored the hole for the thrust bearing. The only thing critical here is the depth of the bore and that there is clearance for the thrust bearing race to rotate without rubbing.


Pic looks like hell, but if you look at the 2 o'clock position you can see the two steps for the different bearings and how badly everything needs to be deburred. The blue portion is the bottom of the radial bearing pocket, the brown is the bottom of the thrust bearing pocket, and the burr on the face is the burr on the face that needs removed.

Having that done I cleaned up all of the burrs and test fit everything. Once everything looked to be working good I decided to add an oiling port to facilitate oiling periodically. I drilled and tapped a 4mm-.07 hole as I already had this size set screw. I didnt have much room to work with, but I was able to get the hole right between the radial and thrust bearing so that should work fine. When tapping this hole only tap enough to get the tap started, then check the fit of your screw periodically to try and get it to lock up in the threads just as the screw meets the surface.

Then I lubricated the bearings and did the final install. Just a light coating of grease will do.

Came out smooth as butter and will make drilling a much more pleasant task.

Y

 

[dabear3428]

What if I told you a $10 outlay would make drilling on your mini lathe much more enjoyable and easier?

Lets face it, drilling on these is not the most pleasurable task compared to larger machines. You're fighting friction on all fronts and really have to manhandle the quill feed wheel to drill anything over an 3/16" (5MM for you metric guys), this can change that.



First you're going to have to look over your tail stock quill screw bearing plate. In the pic below its the part between the bearings and the tailstock handwheel. This is a simple and crude in most cases, plain bearing end cap for your tail stock.

I looked mine over and found a 10mm ball bearing and 18mm thrust bearing would fit the bill. Ordered them from the amazonians for about $10.


They look like this.



View attachment 504107



Now depending on your lathe and the shape of the quill screw bearing plate you may need to use a 4 jaw chuck like I did on this one (PraziSD400), or just a 3 jaw like I did on the last one I did (Prazi SD300). You will also need a saddle stop on your lathe to make hitting the proper depth east and repeatable.


You will need to bore two steps into the bearing plate, a precise bore for the radial bearing, and a clearance bore for the thrust bearing, where only the depth matters. The bore for the radial bearing needs to be a precise sliding fit, and it needs to be done first.


I used a Starrett snap gage to measure the bore as calipers wont give you as precise a measurement for several reasons I wont go into here.




View attachment 504112




Here's this step completed. Just sneak up on the final dimension and try to get as best a final finish as you can. The process of boring this hole will let you work out getting a good finish.



View attachment 504108




With that done I bored the hole for the thrust bearing. The only thing critical here is the depth of the bore and that there is clearance for the thrust bearing race to rotate without rubbing.


Pic looks like hell, but if you look at the 2 o'clock position you can see the two steps for the different bearings and how badly everything needs to be deburred. The blue portion is the bottom of the radial bearing pocket, the brown is the bottom of the thrust bearing pocket, and the burr on the face is the burr on the face that needs removed.

Having that done I cleaned up all of the burrs and test fit everything. Once everything looked to be working good I decided to add an oiling port to facilitate oiling periodically. I drilled and tapped a 4mm-.07 hole as I already had this size set screw. I didnt have much room to work with, but I was able to get the hole right between the radial and thrust bearing so that should work fine. When tapping this hole only tap enough to get the tap started, then check the fit of your screw periodically to try and get it to lock up in the threads just as the screw meets the surface.




View attachment 504109




Then I lubricated the bearings and did the final install. Just a light coating of grease will do.



View attachment 504110





Came out smooth as butter and will make drilling a much more pleasant task.





View attachment 504111
Y

looks great, is there any reason that you did not place the thrust bearing on the inside and the axial (edit radial) bearing on the outside?

 

[Pevehouse]

Looks awesome. I have two prospects wanting to purchase my Prazi stuff. If I keep it this may be in my future plans

 

[RaisedByWolves]

looks great, is there any reason that you did not place the thrust bearing on the inside and the axial bearing on the outside?

I guess you could do it that way if you chose to.

I would venture every lathe will be a little different in how you can go about it. Doing it this way means only one setup so there's that.

What I would really like is for there to be room for two axial bearings, but I'm adding an aftermarket handwheel and I'm tight on space for that as it is.



Also, I would encourage anyone performing this mod to post their make and model of lathe, and the bearings they used for those who may not know what to purchase, or the best way to go about this for their machine.

.

 

[dabear3428]

I guess you could do it that way if you chose to.

I would venture every lathe will be a little different in how you can go about it. Doing it this way means only one setup so there's that.

What I would really like is for there to be room for two axial bearings, but I'm adding an aftermarket handwheel and I'm tight on space for that as it is.



Also, I would encourage anyone performing this mod to post their make and model of lathe, and the bearings they used for those who may not know what to purchase, or the best way to go about this for their machine.

.

was kind of what i was look at, replace the radial bearing with a deep groove ball bearing to get some thrust out of it and by placing it on the outside it would not see as much axial load, being that the major load is in the extension of the quill, that way getting almost 2 axial bearings in the space. could also recess the handwheel to make room for thrust bearing on the outside.
any way nice work, it is not my intention to pick your great work apart just curious.