Pork chops
Posted: Sun Mar 11, 2012 12:50 pm
Every Shopsmith I've gone through has had reasonable to bad wear to the speed control assembly. If you've ever taken these apart, you know it takes the form of both worn/misshapen quadrant teeth and spread out wings on the quadrant holder. (not sure if there's actually a name for that piece, so I'll just use quadrant holder)
I've been successful in all cases in my refurbishing these parts by putting a washer shim between the wings to take up slack, (I talked about this in a previous post, I was reluctant to squeeze them together with a screw/nut combo for fear of breakage) and doing a bit of filing cleanup to the quadrant teeth. Obviously, not too much material can be removed, but a little cleanup by flattening the tops with a fine flat file & going between the teeth with a small triangular file has resulted in smooth working units.
However, when I looked at the assembly from my most recent project, (and here's where I wish I'd taken a "before" picture, but I didn't think I'd end up with an "after" pic, so I didn't bother) I figured I'd experiment a bit.
First, I dealt with the quadrant teeth. They had the usual bowed shape to them & rather than do any filing, I decided to use a small flat end punch (in the pic) and place it against the bowed side of each tooth & gently tap it & run it along the tooth from end to end to see if it would go back to shape. To my delight, it did with almost no urging. in a few minutes, all the teeth were straight & a very light file cleanup finished it up. I ended up with more material than usual left because almost no filing was done. Then just a wire wheel to smooth it off.
Next the wing problem...here's where a pic would have been great because I've never seen an assembly this bad. The wings had spread so that there was a strong 1/4" play between them & the quadrant. No way to shim this & with that much space, I figured I couldn't pull them together without breaking a wing.
I decided to try something new because it was a lost cause otherwise, I had nothing to loose. I put the assembly in a vise pressing the wings together (very lightly) & heated the spread one(from my experience it's always only one that's out) with a Bernz-o-matic bottle torch. I noted almost immediately that it wanted to fall out of the vise...the wing was responding to inward pressure by moving. I kept heating & wound in the vise until I straightened the wing, (LET IT COOL, THIS IS REALLY IMPORTANT, IT'S REALLY HOT...DON'T ASK HOW I KNOW THIS) After cool, I took it out of the vise & it retained it's new correct shape.
Using a folded piece of heavy weight aluminum foil as a shim to keep from too tight a fit, I installed the quadrant,tapping in the roll pin, pulled out the foil, and ended up with what looks to be my best re-do job on this assembly.
[ATTACH]16652[/ATTACH]
It runs as smooth as silk, and appears to be completely sound.
A couple of notes for the analyticals in the group: I did not heat it until it was red hot, only until I saw that it was loosening in the vise which told me it was moving easily. Yes, I know that tapping the aluminum teeth probably causes fatigue...probably the same for the wing movement.
But the bottom line here is: it's a repair, not a replacement. It took me about 1/2 hour & cost virtually nothing, works like new and, while it might not allow the machine to last another 50 years, I'll bet it will last a good while.
I've been successful in all cases in my refurbishing these parts by putting a washer shim between the wings to take up slack, (I talked about this in a previous post, I was reluctant to squeeze them together with a screw/nut combo for fear of breakage) and doing a bit of filing cleanup to the quadrant teeth. Obviously, not too much material can be removed, but a little cleanup by flattening the tops with a fine flat file & going between the teeth with a small triangular file has resulted in smooth working units.
However, when I looked at the assembly from my most recent project, (and here's where I wish I'd taken a "before" picture, but I didn't think I'd end up with an "after" pic, so I didn't bother) I figured I'd experiment a bit.
First, I dealt with the quadrant teeth. They had the usual bowed shape to them & rather than do any filing, I decided to use a small flat end punch (in the pic) and place it against the bowed side of each tooth & gently tap it & run it along the tooth from end to end to see if it would go back to shape. To my delight, it did with almost no urging. in a few minutes, all the teeth were straight & a very light file cleanup finished it up. I ended up with more material than usual left because almost no filing was done. Then just a wire wheel to smooth it off.
Next the wing problem...here's where a pic would have been great because I've never seen an assembly this bad. The wings had spread so that there was a strong 1/4" play between them & the quadrant. No way to shim this & with that much space, I figured I couldn't pull them together without breaking a wing.
I decided to try something new because it was a lost cause otherwise, I had nothing to loose. I put the assembly in a vise pressing the wings together (very lightly) & heated the spread one(from my experience it's always only one that's out) with a Bernz-o-matic bottle torch. I noted almost immediately that it wanted to fall out of the vise...the wing was responding to inward pressure by moving. I kept heating & wound in the vise until I straightened the wing, (LET IT COOL, THIS IS REALLY IMPORTANT, IT'S REALLY HOT...DON'T ASK HOW I KNOW THIS) After cool, I took it out of the vise & it retained it's new correct shape.
Using a folded piece of heavy weight aluminum foil as a shim to keep from too tight a fit, I installed the quadrant,tapping in the roll pin, pulled out the foil, and ended up with what looks to be my best re-do job on this assembly.
[ATTACH]16652[/ATTACH]
It runs as smooth as silk, and appears to be completely sound.
A couple of notes for the analyticals in the group: I did not heat it until it was red hot, only until I saw that it was loosening in the vise which told me it was moving easily. Yes, I know that tapping the aluminum teeth probably causes fatigue...probably the same for the wing movement.
But the bottom line here is: it's a repair, not a replacement. It took me about 1/2 hour & cost virtually nothing, works like new and, while it might not allow the machine to last another 50 years, I'll bet it will last a good while.