Thread: New Chuck backing plate run out

Originally Posted by neevo

Does the back plate screw on nicely now?

It still needs a smidge removed from the thread to allow it to hit the register

I just went and machined the back out of the threaded part on the plate so it hits the register and its still got a mile of run out.

Ill wait until the weekend to machine the face of it so I have more time to make sure I get it right.

As mentioned before. Don’t worry about the run out yet, just make sure you are getting the same run out each time.

Originally Posted by neevo

As mentioned before. Don’t worry about the run out yet, just make sure you are getting the same run out each time.

Took the backing plate on and off 3 times and as best as I could measure it, it seems to have the same amount of run out.

I couldnt help myself, I machined a very light cut over the whole thing......the wobbling bothered me On the weekend Ill machine the recess for the chuck to register and it should be good.

IMG_4547.jpg

I am still getting around .03 - .05mm movement on the indicator after machining but its difficult to tell if the indicator is picking up the finish or actual run out. My spindle measures zero or very little run out when there is no weight on it but it may have a little bit of play in the bearings, who knows, its an old lathe and so am I
Being new to this I dont really know what is acceptable.

Seems like a lot of run out. Worth checking what’s causing that.

See if you can get the gauge to move by trying to jiggle the back plate.

Originally Posted by neevo

Seems like a lot of run out. Worth checking what’s causing that.

See if you can get the gauge to move by trying to jiggle the back plate.

Bingo, yes I can. It looks like the retaining nut that snugs the spindle tight has a bit of play as I can move it horizontally quite a bit.

Problem solved. Now getting next to zero run out, well it is around .01mm at most but I pretty sure thats my poor finish interfering.

Do you mean axially (in and out along the line of rotation)?

Originally Posted by pippin88

Do you mean axially (in and out along the line of rotation)?

Um I think we are both talking about the same thing. It had some end play in the spindle which was making the indicator read the backing plate like it was a wobbly old wheel.

On my Hercus 9C there is a split locking adjuster ring at the change gear end to take up that axial (left/right) play in the spindle. Tighten that so you remove the play but not right to cause excess drag. Will remove all the axial play and retest backing plate.

Originally Posted by neevo

On my Hercus 9C there is a split locking adjuster ring at the change gear end to take up that axial (left/right) play in the spindle. Tighten that so you remove the play but not right to cause excess drag. Will remove all the axial play and retest backing plate.

Thanks, yes the same as the south bend (being a clone). I did exactly that yesterday and solved the issue.

I am going to upgrade the felt washer behind the split locking nut with a thrust bearing at some stage. Does the hercus use a felt washer as well or a thrust bearing?

My Hercus uses a compressed plastic type washer I believe. Keep meaning to do the same and convert to a thrust washer but it’s never given me any trouble.

Originally Posted by neevo

My Hercus uses a compressed plastic type washer I believe. Keep meaning to do the same and convert to a thrust washer but it’s never given me any trouble.

I have full intentions of stripping mine down, replacing the felts, upgrading things like that thrust bearing and painting it properly one day. But for now I just wanted to get it all working correctly and machining as accurate as Ill ever need.

I have had a thrust bearing in my ebay watchlist for a while but its pricey so I need to take the dimensions to my local bearing supplier I think.
https://www.ebay.com.au/itm/New-Spin...p/152445466871

Go to a bearing place. Will be SIGNIFICANTLY cheaper for sure!

Felt replacement is best done earlier if you can. I bought a Southbend refurbishment kit off eBay (I think) and was brilliant! My felts were non existent, so running the lathe could have been a bad thing for too much longer.

I cant see this as being an issue but the chuck I bought was 160mm and the backing plate is only 150mm. Well after measuring it is actually closer to 155mm, but it is smaller than the chuck.

The register recess and mounting holes are no where near the outer edge so I cant see an issue, can anyone tell me if this will be a problem??

Thanks.