Author Topic: Where would you start ?  (Read 2893 times)

Offline DavidA

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Where would you start ?
« on: May 04, 2014, 01:50:38 PM »
Here is a little light entertainment. In case anyone is getting bored.

Assume you have just acquired an old lathe. It comes with a face plate and a four jaw chuck.

But there are a couple of snags.

There is no back plate for the chuck.

But more importantly,  the faceplate register won't fit the register on the lathe mandrel. It is too small.

On the positive side,  the thread on the plate fits the mandrel thread.

So,  how would you begin to fit your faceplate to the mandrel,  bearing in mind that the future accuracy of the whole lathe depends upon the register fit.

Dave.

Offline BillTodd

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Re: Where would you start ?
« Reply #1 on: May 04, 2014, 02:09:34 PM »
1) fit face plate  (does not matter if it wobbles)
2)fix work piece (for new backplate) to face plate
3) machine register and thread into work piece (it will be cut concentric and round regardless of the wobble)
4) fit new backplate to spindle and carefully machine to fit chuck (there are some very good suggestions on lathes.co.uk)

4a) before fitting chuck to backplate  carefully fix the faceplate to it (check runout with dti) then machine correct register into faceplate.

5) fit faceplate and skim to flat.

Bill
« Last Edit: May 04, 2014, 07:58:46 PM by BillTodd »
Bill

Offline philf

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Re: Where would you start ?
« Reply #2 on: May 04, 2014, 06:05:20 PM »
Here is a little light entertainment. In case anyone is getting bored.

Assume you have just acquired an old lathe. It comes with a face plate and a four jaw chuck.

But there are a couple of snags.

There is no back plate for the chuck.

But more importantly,  the faceplate register won't fit the register on the lathe mandrel. It is too small.

On the positive side,  the thread on the plate fits the mandrel thread.

So,  how would you begin to fit your faceplate to the mandrel,  bearing in mind that the future accuracy of the whole lathe depends upon the register fit.

Dave.

Dave,

Can you not screw the faceplate on the wrong way round so that the register could be bored out. A parallel spacer (perhaps an old bearing) between the spindle register clamping face and the faceplate should hold the faceplate nice and square. After boring out the register, lightly skim the clamping face of the faceplate boss before unscrewing it and then lightly skim the faceplate.

Phil.
Phil Fern
Location: Marple, Cheshire

Offline DavidA

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Re: Where would you start ?
« Reply #3 on: May 05, 2014, 01:43:44 PM »
Phil,

That's what I would do.

Seems to me to be the logical way. You would probably need a small spacer to ensure that there was sufficient  room to get the proper depth of register . plus you will have to remember to square the end before removing the plate and screwing it back on the right way.

Dave.