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9" SM Utilathe Restoration
- Thread starter YYCHM
- Start date
Found an image of my original motor mount.
I'm thinking the handle had a extension added (dark area)? As pictured it's in it's relaxed state, so no way the cover would close. Also, the tensioned slot could never be achieved.
I had to slot out the mounting holes an 1/8" on the tensioning bracket to make it fit on my bed, another discrepancy.
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The handle does look modified, it may have added leverage during a belt change since the motor can be a bit heavy.
When I put the new motor on mine I left the motor mount bolts loose, put the belt on, put the handle in the tensioned slot then tightened the bolts. Leaving the bolts loose let the motor find a spot that set the handle in the slot and still had tension to run the spindle. IIRC moving the motor up on the mount moved the handle toward the front of the machine.
When I put the new motor on mine I left the motor mount bolts loose, put the belt on, put the handle in the tensioned slot then tightened the bolts. Leaving the bolts loose let the motor find a spot that set the handle in the slot and still had tension to run the spindle. IIRC moving the motor up on the mount moved the handle toward the front of the machine.
SPINDLE:
OD 1.179"
Len 6.0"
Key Way 0.125"
SCREW:
1/2” LH ACME (Assuming ACME implies a fixed pitch)
Brent H
Ultra Member
Hey Craig,
what are the grooves running around your spindle for?
ACME is a trapezoidal type thread (like a square thread but at 29°).
is it 1/2 and 10 threads per inch or 8?
What you can do is make a threaded insert with your good Acme threads - I can send you drawings. - I will machine the piece I have to length for you - if you have the exact diameter I can machine the OD as well.
1/2 acme is a bugger to thread on the lathe as it is not much bore diameter to get a boring bar into. They sell taps but they can be costly.
easy way is to press fit your current threads into the new spindle - Abom79 makes a new acme treaded tailstock spindle and makes a brass insert - have a gander on youtube.
what are the grooves running around your spindle for?
ACME is a trapezoidal type thread (like a square thread but at 29°).
is it 1/2 and 10 threads per inch or 8?
What you can do is make a threaded insert with your good Acme threads - I can send you drawings. - I will machine the piece I have to length for you - if you have the exact diameter I can machine the OD as well.
1/2 acme is a bugger to thread on the lathe as it is not much bore diameter to get a boring bar into. They sell taps but they can be costly.
easy way is to press fit your current threads into the new spindle - Abom79 makes a new acme treaded tailstock spindle and makes a brass insert - have a gander on youtube.
10 TPI. Haven't a clue what the grooves are for (there is a hole drilled through the second groove to the screw). Oil reservoir for the gits oiler perhaps?
I bought a 1/2x10tpi LH and a 3/8x10tpi RH from MPI Tools and it worked out to just under $65 usd to my door. I made a new cross slide nut and it worked out well considering I've seen the taps for $100 usd and more just for one tap.
https://mpitools.com/product-category/acme_taps/
https://mpitools.com/product-category/acme_taps/
Brent H
Ultra Member
Yotabota,
That is good to know. 9/16 is about the limit to internal thread acme and it takes prep. I had success running the chuck backwards onto the tool bit verses running forward and feeding away from the chuck.
With a tap you could make the threaded insert out of brass or bronze as was done on Abom79's video (he internal threaded though)
That is good to know. 9/16 is about the limit to internal thread acme and it takes prep. I had success running the chuck backwards onto the tool bit verses running forward and feeding away from the chuck.
With a tap you could make the threaded insert out of brass or bronze as was done on Abom79's video (he internal threaded though)
Johnwa
Ultra Member
Here’s a picture of the spare quill that I have. It has a threaded bronze insert held in with a roll pin. It looks like the roll pin was put in, bored out and then a tap was run through. It seems like a hard way to do it, but I can see where the roll pin has a partial thread cut in it.
I’ve seen similar attachments but with the roll pin far enough off center to not interfere with the threads.
I’ve seen similar attachments but with the roll pin far enough off center to not interfere with the threads.
Attachments
Not quite ready to trash the scored spindle in order to obtain an ACME thread insert yet.
But look what happens to be the right thread. That's the cross slide nut. Also, I'm seeing ACME thread couplers are available. One of those could be turned round to make an insert.
But look what happens to be the right thread. That's the cross slide nut. Also, I'm seeing ACME thread couplers are available. One of those could be turned round to make an insert.
historicalarms
Ultra Member
I have bought Acme 1" threaded rod & nuts (in-stock, not a special order thing) at a bolt supply store in Red Deer and they had a rack of smaller sizes as well, there should be a fastener place in cowtown somewhere that carries that stuff.
Make it 1.180" please.
Well...… I figured out why the motor is bouncing
This pulley is really loose on the motor shaft. Tightening down the lock screw cants the pully and pulls it eccentric.
It's almost as if the bore on the pulley is tapered? It fits on the shaft one way but not the other.
The motor shaft is a little chewed up but appears to be 5/8".
I was a little perplexed by the motor bounce. With the belt removed is runs real smooth. Install the belt and the motor would bounce. Was really noticeable in low gear.
With luck the pulley Brent has sent me will fit the motor shaft better other wise I'll have to figure out how to bush the slop out.
This pulley is really loose on the motor shaft. Tightening down the lock screw cants the pully and pulls it eccentric.
It's almost as if the bore on the pulley is tapered? It fits on the shaft one way but not the other.
The motor shaft is a little chewed up but appears to be 5/8".
I was a little perplexed by the motor bounce. With the belt removed is runs real smooth. Install the belt and the motor would bounce. Was really noticeable in low gear.
With luck the pulley Brent has sent me will fit the motor shaft better other wise I'll have to figure out how to bush the slop out.
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