Boxford 280 spindle nose runout

I have a Boxford 280 lathe. I have recently been tuning out all the play and trying to adjust everything to optimum.

I recently acquired a nice Burnard collet chuck but when I fitted I had around 6 thou run out at the work piece.

I removed the chuck from the back plate and checked the register and still had run out.

I then removed the back plate from the spindle and checked the spindle itself.

I have about 2 thou run out on the face of the spindle (first picture) but none the inside edge of the spindle (second picture) which tells me the spindle is not bent.

I have created an album with pictures of what I am trying to describe.

Now I could machine the face square, but if that is the correct thing to do then I would have expected this to have already been done sometime in the 30+ years since this left the factory.

The nose and spindle appear not to be one piece but I can see no way of removal or adjustment bar total removal of the spindle itself which I am keen to avoid.

Any suggestions?

Thanks in advance.

Edited By Gavlar on 22/06/2020 11:51:36

Edited By Gavlar on 22/06/2020 11:59:13

Put the backplate onto the spindkle and remachine that for your specific lathe, then remount the collet chuck, thats the way it has been done for years.

It will only take a tiny skim of the face of the backplate to sort that out, and the radial runout of the register should be checked at the same time. It is common for the chuck to fit tightly on the register, but if it doesn't, don't worry, you will have to get the radial running well by leaving the chuck fixing screws slightly loose and get it running before fully tightening them. You need to check the chuck with different size work in it, preferably ground stock.

Before any machining, make sure the threads of the spindle are absolutely clean and also the backplate threads.

Edited By old mart on 22/06/2020 13:51:30

Boxford didn't make a 280 lathe, but Myford did.

The fitting is Camlock, so the spindle doesn't have a radial register or threads. The Camlock system primarily mates on the outer taper. Measurements on my lathe spindle Camlock give a runout on the back face of 0.01mm and a runout on the outside taper estimated to be 0.002mm. The inside of the taper plays no part in mounting the chuck so it's runout, or otherwise, doesn't tell one anything.

The runout on the back face seems a lot to me, but it would be a bad idea to try and machine it. I think Camlock parts are hardened which makes life more difficult. I'd agree wth JasonB, the best bet is to machine the chuck backplate in situ. But make sure you mark it so that it can be replaced in the same orientation each time, otherwise it won't run true.

Andrew

The runout of the spindle face (ist photo) looks to me like a bent spindle,the position of the dial gauge will not tell you much the mounting angle iis wrong,suggest a test bar in the spindle bore would give a more accurate reading,you could use a taper centre or sleeve. The method of correcting the runout should be removal of the spindle,to see where the bend is, if the bend is between the bearing and the spindle face, the runout can be corrected by mounting the spindle in a cylindrical grinder and grind the chuck mounting true. If the bend is between the bearings,then there not much one can do to correct it. I am not a great believer in correcting errors like this by machining on the lathe with either carbide tooling or toolpost grinders,the spindle face really needs to have very good finish and be square to the spindle axis. You could possibly live with Jasons method by machining the back plate and then mark the spindle and backplate so they always fit to the orientation,of course the other accesories willhave a woble,so back plates for the three and four cucks will need correcting, plus the face plate which have to be fitted and the front face machined true,which is not a problem as it will be soft cast iron.I have seen machine movers lift lathes with a strop around the chuck,not good practice but it happens.

They did Andrew, it was quite similar to a Harrison M250.

It's strange that the flat face is so far out of plane because it would have been ground along with the small tapered register. That small internal taper was probably used to mount the spindle between centres when it was ground.

If I remember correctly, these two surfaces are designed to come into contact one after the other - so cone first followed by the flat surface/register. I think the cone is a very small interference fit of maybe ~ 0.0001" to ensure centralisation of the chuck. It would be hard to skim that surface and maintain the right kind of fit.

Martin.

Edited By blowlamp on 22/06/2020 14:43:16

Oh dear! The Camloc mounting is indeed heat treated, and unfortunately so is the body of the Burnard collet chuck, assuming it is the integral Camlock mount type.. It does look as if the spindle is bent. The next thing to do is fit a Morse sleeve in the spindle taper to see if that runs true. Can you see if the conical surface in the second photo is concentric with the internal taper? It may have been ground by a previous owner.

Unless the spindle is somehow fabricated from two parts, rectification looks near impossible.

Thank you. I shall machine the back plate.

On my Boxford 280 I have drilled a little dimple by one camlock mounting hole and corresponding dimples on the chucks so that they always go back in the same orientation.

Hi Gav, I have a Boxford 10-20, or X10 as Boxford refer to them, but essentially the same as yours I believe. The bad news is that last night I clocked the runout on the face of the spindle, and it was as near zero as I could see with a 0.01mm clock. Which leads me to suspect that you have a problem with your spindle. I have adjusted my spindle bearings but have never taken the spindle out. Unfortunately I think that if you have a bent spindle you are never going to get good results, although I agree that bespoke back plates for each chuck, assembled repeatably each time, will be your next best solution. I would, however, suggest rigorous re measurement of that runout ensuring you are not picking up any tiny chips or dings.

ATB, John

Just an update;

I did try and work around the bent spindle but whilst decent work is possible, it wasn't easy and was nigh on impossible to repeat an action if the chuck was removed or the work removed from the chuck. On top of this, the low rumble at low speed, which I origonaly thought was normal and the slow oil lead from the head stock via the spindle bearings, was all starting to annoy me.

A new spindle was way to expensive, even if Boxford could still supply them.

A couple of days ago a Boxford 10-20 came up on ebay only an hours drive from me. The 10-20 is pretty much exactly the same as the 280 but with 1/2" less swing. The seller had removed all the wiring in anticipation of fitting a VFD and had broken it down into all it's sub assemblies then left it to gather dust at the back of his garage.. It was sold with a good few desirable and expensive extras that I didn't already have such as a full set of changegears, brand new 4 jaw, steadies etc. Long story short, I picked it up yesterday and today swapped the headstock, top slide riser and tailstock onto my machine

What a difference!! No rumble at low speed, no oil leak and no decernable runout..

The moral is; Dont let your heart rule your head when you are buying second hand lathes!

What's left is a complete yet unslable lathe so if you know of anyone that needs any X10 parts........

Hi Gavlar - would be interested in some 280 spare if you still have some... pls let me know

Not too relevant to the problem outlined by the OP, but interesting all the same. When I first purchased my ML10, the run out on the outside of the Burnered 3 jaw chuck was easily seen when the chuck rotated, let alone measuring it with a DTI. I checked the chuck again, using some ground silver steel. Oh dear it was just as bad. Thoughts of pigs in pokes loomed large!

It turned out that I had a piece of swarf in the nose thread of the lathe. A good clean resulted in normality. I am still totally amazed that a small piece of swarf could cause such a huge run out. Anyone with a similar problem would be well advised to look at the chuck mounting for foreign bodies before looking elsewhere!!

Andrew.

I have had similar experiences with a Denford Easiturn. I machined it

REgards.

David.