Turn Off Lathe Backing Plate...Tips?

[francist]

the face plate has almost no clearance behind it. I can't imagine being able to cut without hitting the bearing housing behind it.

An oscillating tool (aka Fein tool) can get into some pretty tight spots and funny angles. I’ve never tried one on metal but they do make carbide blades for them.

-frank

 

[G-ManBart]

An oscillating tool (aka Fein tool) can get into some pretty tight spots and funny angles. I’ve never tried one on metal but they do make carbide blades for them.

-frank

Funny, I would never have thought of that, but I have a brand new Fein Tool in the box that I've never used! I was at a training class and got it as a prize at the end as I recall. I'll have to see what blades I have for it if I wind up having to switch to a destructive removal.

 

[markba633csi]

I know you've tried Kroil but what about 50/50 ATF and acetone? I have not seen a case yet where it didn't work, given sufficient time to soak.
-M

 

[G-ManBart]

I know you've tried Kroil but what about 50/50 ATF and acetone? I have not seen a case yet where it didn't work, given sufficient time to soak.
-M

I haven't tried that, but it did occur to me. I'm hoping the block for the bull gear will be the kicker it needs...we'll see!

 

[mattthemuppet2]

I seem to remember a thread on here or PM where a guy in a similar situation went through some iterations of what you're doing. He did the lock bar clamped to the end of the spindle and the large lever on the face plate like you have. What worked for him was making the lever on the face plate really long, I think 6 or 8ft, thick gauge 1-1/2" square pipe if I remember, and hung something heavy on the end of it. Like a bag of concrete or a sack of potatoes. Took a couple of days but one morning he went back in and the weight was resting on the floor and the backplate was loose.

Heat never hurts too. I personally prefer alternating heat and cold, a few rounds of that usually does the trick. A bit harder on something with so much thermal mass, but the principle is the same. As others have suggested, heat up the backplate/ spindle as hot as you dare with regards to the bearings, then stuff chunks of dry ice into the spindle. Then repeat, all the while having your lever pre-tensioned with the weight. If that doesn't work one day, go back and do it the next. It'll come eventually.

love the picture of your dog by the way!

 

[Jimsehr]

I think if I were going to sacrifice the plate I would trepan it almost thru and a little over 2 1/4 dia. Better to scrap the plate then hurt the lathe.

 

[SLK001]

To prevent a lot of future chuck sticks, cut a washer out of parchment (best) or wax paper (good) 2-3/4" OD by 2-1/4" ID and place it between the chuck and the spindle shoulder.

This washer won't help if you jam on a chuck with swarf in the threads, but if it is just spun on too tight, it will prevent any metal to metal seizing.

 

[G-ManBart]

I seem to remember a thread on here or PM where a guy in a similar situation went through some iterations of what you're doing. He did the lock bar clamped to the end of the spindle and the large lever on the face plate like you have. What worked for him was making the lever on the face plate really long, I think 6 or 8ft, thick gauge 1-1/2" square pipe if I remember, and hung something heavy on the end of it. Like a bag of concrete or a sack of potatoes. Took a couple of days but one morning he went back in and the weight was resting on the floor and the backplate was loose.

Heat never hurts too. I personally prefer alternating heat and cold, a few rounds of that usually does the trick. A bit harder on something with so much thermal mass, but the principle is the same. As others have suggested, heat up the backplate/ spindle as hot as you dare with regards to the bearings, then stuff chunks of dry ice into the spindle. Then repeat, all the while having your lever pre-tensioned with the weight. If that doesn't work one day, go back and do it the next. It'll come eventually.

love the picture of your dog by the way!

I've gotten to the point where the extra leverage is causing the bar locked to the end of the spindle to slip. I tried making a set of V-shaped pipe jaws with teeth and that seemed to take a bit more before it would slip, but it still slipped eventually. I ordered one of the plastic gear blocks that fits the bull gear and has an extension which bears on the main housing. I can pretty easily extend the bar on the backing plate another 3-5 feet, but I've got to get the spindle truly locked or nothing is likely to work.

Once the gear block gets here I'll try just the lever I have, then go to heat with ice in the spindle and see what happens. If those don't work, I'll load up the bar with 100+lbs of weight for pre-load, then apply heat with ice in the spindle. If that doesn't work I'll double the extension, put as much weight as I can get on it and give it a couple of days. If that still hasn't done the trick I'm probably going to be fed up and want to destroy the backing plate...lol!

The dog is my boy Charlie when he was just a young stud. He looked scary but was a big sweetie who loved people and other dogs...not so much cats! We had to say goodbye to him three weeks ago tomorrow...he was 15 which is pretty amazing for a big dog. Okay...tearing up now...

 

[matthewsx]

I've gotten to the point where the extra leverage is causing the bar locked to the end of the spindle to slip. I tried making a set of V-shaped pipe jaws with teeth and that seemed to take a bit more before it would slip, but it still slipped eventually. I ordered one of the plastic gear blocks that fits the bull gear and has an extension which bears on the main housing. I can pretty easily extend the bar on the backing plate another 3-5 feet, but I've got to get the spindle truly locked or nothing is likely to work.

Once the gear block gets here I'll try just the lever I have, then go to heat with ice in the spindle and see what happens. If those don't work, I'll load up the bar with 100+lbs of weight for pre-load, then apply heat with ice in the spindle. If that doesn't work I'll double the extension, put as much weight as I can get on it and give it a couple of days. If that still hasn't done the trick I'm probably going to be fed up and want to destroy the backing plate...lol!

The dog is my boy Charlie when he was just a young stud. He looked scary but was a big sweetie who loved people and other dogs...not so much cats! We had to say goodbye to him three weeks ago tomorrow...he was 15 which is pretty amazing for a big dog. Okay...tearing up now...

They give so much more love than humans, that's why their lives are so much shorter....

 

[G-ManBart]

I think if I were going to sacrifice the plate I would trepan it almost thru and a little over 2 1/4 dia. Better to scrap the plate then hurt the lathe.

I'm glad you mentioned that. If I get to that point I was wondering if a trepan cut might work, and it would also cut down on a couple of pounds of chips.