- Joined
- Mar 2, 2021
- Messages
- 84
Hello!
I’m working on a spindle for a slow speed grinder / diamond lap that I’m building.
I prototyped the grinder using pillow blocks and bearings and it came out OK, but I decided I’d try my hand at making a proper spindle.
I’m using designs from this book as a starting point:
I decided to make the spindle from 12L14 to make my life easier. I picked up some 2” round from onlinemetals.com as my fav local metal supply place does not carry 12L14 (Alan Steel & Supply in Redwood City).
The design I picked is a 7” cartridge spindle with two front bearings and one rear bearing, although mine will be a solid spindle without a center bore and the spindle nose will be machined to register with an inset shoulder on a 6” aluminum lap plate rather than a morse taper:
First step was to machine the clamping nut for the front bearings. This nut clamps the inner bearing races against each other and a shoulder on the spindle nose.
I didn’t have a carbide insert inside threading tool handy so I ground my own on my pedestal grinder and cleaned it up and honed it on my Deckel clone:
The front bearing nut has 24 tpi threads and 0.125” clearance so that the nut rests only on the threads and against the inner bearing race.
Next up, I faced and center drilled the 2” round. Since I did this without cleaning up the OD, and by flipping the part around in my 4-jaw, I was not counting on the newly faced ends to be particularly true.
I then set up the work between centers and got to work machining the spindle nose and roughing the spindle profile. I generally use carbide inserts on my PM-1640 lathe.
I picked up inexpensive sealed bearings from Amazon; 25x47x12mm for the fronts and 20x37x9mm for the back.
I finished the OD for the front and rear bearings, aiming for a tight, bordering on interference fit, but went a bit far with the emory paper and ended up with a very close sliding fit.
Next up, I machined the threads for the front bearing clamp nut. I did this in 0.005” passes, and stopped the lathe short ~0.050” from my desired end. My PM-1640 is three phase and I set it up with a VFD and added a jog joystick when I first got it. I used the jog to cut the last ~0.050” of threads, which allowed me to stop the thread very precisely without any kind of gutter.
I prefer not to disengage the half nut in favor of backing out the cross slide and running in reverse, especially since my lathe has reverse on the hand lever.
The blue painters tape below increases the OD to allow me to “hold” the front bearing clamping nut on the shaft during threading for easy access for test fitting (ie without having to disengage the tailstock from the work).
I was able to achieve a very close, tight fit between the spindle and the clamping nut.
A quick test assembly has things looking good!
Next up is to machine the threads for the pulley nut that clamps the pulley to the rear bearing race, to the shoulder at the end of the spindle. After a quick cleanup of the faces on the ends of the spindle, that will be the spindle done and I’ll get started on the spindle body.
More to come!
I’m working on a spindle for a slow speed grinder / diamond lap that I’m building.
I prototyped the grinder using pillow blocks and bearings and it came out OK, but I decided I’d try my hand at making a proper spindle.
I’m using designs from this book as a starting point:
Spindles (Workshop Practice Series): Harprit Sandhu: 9781854861498: Amazon.com: Books
Spindles (Workshop Practice Series) [Harprit Sandhu] on Amazon.com. *FREE* shipping on qualifying offers. Spindles (Workshop Practice Series)
www.amazon.com
I decided to make the spindle from 12L14 to make my life easier. I picked up some 2” round from onlinemetals.com as my fav local metal supply place does not carry 12L14 (Alan Steel & Supply in Redwood City).
The design I picked is a 7” cartridge spindle with two front bearings and one rear bearing, although mine will be a solid spindle without a center bore and the spindle nose will be machined to register with an inset shoulder on a 6” aluminum lap plate rather than a morse taper:
First step was to machine the clamping nut for the front bearings. This nut clamps the inner bearing races against each other and a shoulder on the spindle nose.
I didn’t have a carbide insert inside threading tool handy so I ground my own on my pedestal grinder and cleaned it up and honed it on my Deckel clone:
The front bearing nut has 24 tpi threads and 0.125” clearance so that the nut rests only on the threads and against the inner bearing race.
Next up, I faced and center drilled the 2” round. Since I did this without cleaning up the OD, and by flipping the part around in my 4-jaw, I was not counting on the newly faced ends to be particularly true.
I then set up the work between centers and got to work machining the spindle nose and roughing the spindle profile. I generally use carbide inserts on my PM-1640 lathe.
I picked up inexpensive sealed bearings from Amazon; 25x47x12mm for the fronts and 20x37x9mm for the back.
I finished the OD for the front and rear bearings, aiming for a tight, bordering on interference fit, but went a bit far with the emory paper and ended up with a very close sliding fit.
Next up, I machined the threads for the front bearing clamp nut. I did this in 0.005” passes, and stopped the lathe short ~0.050” from my desired end. My PM-1640 is three phase and I set it up with a VFD and added a jog joystick when I first got it. I used the jog to cut the last ~0.050” of threads, which allowed me to stop the thread very precisely without any kind of gutter.
I prefer not to disengage the half nut in favor of backing out the cross slide and running in reverse, especially since my lathe has reverse on the hand lever.
The blue painters tape below increases the OD to allow me to “hold” the front bearing clamping nut on the shaft during threading for easy access for test fitting (ie without having to disengage the tailstock from the work).
I was able to achieve a very close, tight fit between the spindle and the clamping nut.
A quick test assembly has things looking good!
Next up is to machine the threads for the pulley nut that clamps the pulley to the rear bearing race, to the shoulder at the end of the spindle. After a quick cleanup of the faces on the ends of the spindle, that will be the spindle done and I’ll get started on the spindle body.
More to come!
