Can anyone identify this mystery feed screw please?

[Keith LongParticipant @keithlong89920]

link inserted 'cos I can't get the picture to appear – sorry folks!!

Hello
I'm hoping that someone can help me identify the "mystery feed screw" in the picture that the above link leads to.

It came as a "bonus" item with a selection of lathe spares – mainly Boxford, but not exclusively – that I recently bought via E-Bay. The seller didn't know what it was from, or it's history, as he was selling on behalf of a friend.

The main thread is 10tpi left hand, and has been measured over the full 60 turns to make sure that it isn't 2.5mm pitch. The diameter is "almost but not quite" 7/16 in. as it's actually a bit over size at 0.445 in. dia (11.30mm). I don't have the facilities to determine the flank angle on the thread but with it being 10tpi I think that it is most likely Imperial Acme rather than Metric trapezoidal.

From the gear in the middle of the shaft I've tended to assume that it is a cross-slide feed screw from a lathe with power cross feed, but I could well be wrong – might it be from a milling machine table?

The gear itself is a bit of a mystery. It's got 12 teeth, it's integral with the shaft and from the diameter could be either 20dp or 1.25mod – the diameter is a bit small for either at 0.683in. or 17.35mm. I've tried some Myford gears with it and while they will mesh they aren't a perfect fit. The gears I've tried are a change wheel (14.5deg. p.a) and a spindle gear which I believe is 20 deg. p.a. Certainly they feel "notchy" with each other and both feel a lot worse with the gear on the shaft. I don't have a 1.25mod gear to try it with.

The plain larger diameter part of the shaft is again 0.683in. (17.35mm) o.d. The surface finish on this while good is not what I would expect for a bearing surface.

The thin "tail" of the shaft is 0.370in. (9.38mm) diameter and has what appears to be a machined in, narrow, shallow groove, running axially for about 3/4s of the length of this part of the shaft, which has a good finish that could run in a plain bearing.

The final small diameter on the end is 0.311in. (7.91mm) presumably for the handwheel and the retaining thread seems to be 1/4 BSW.

I haven't found any markings on the shaft at all to indicate manufacturer or part number.

Overall it shaft appears well made and doesn't have any witness marks on it to indicate wear, so it would seem to be either totally unused or with very little use. If anyone recognises the part I'd be grateful if they would let me know, otherwise it's likely to wind up being adapted for use as a feed screw for a new cross slide for one of my old lathes.

Many thanks for looking.

Keith

[Keith LongParticipant @keithlong89920]

[Ady1Participant @ady1]

linky winky

 

Edited By Ady1 on 24/08/2013 16:26:05

[Keith LongParticipant @keithlong89920]

Thank you Ady1 – it wouldn't work for me – looks like I've got the "bug" that others have reported.

Keith

[Ady1Participant @ady1]

All my problems ended in firefox when I did tools-options-privacy

Then accepted cookies from sites and 3rd-party cookies from sites

[hushParticipant @hush]

Hi

The screw spindle is for a Boxford cross slide with power feed. Your picture with dimensionsare the same as one I have on my Boxford. I replaced the cross slide on my machine about 20 years ago, the old onehas languished in the tray beneath the tailstock ever since. The main leadscrew is 3mm pitch but the cross slide is 10 tpi. and the thimble is divided to give 2.5mm for one complete turn. It is not an exact conversion but close enough for all I do.

Regards

Ivan

[Keith LongParticipant @keithlong89920]

Hi Ivan

Thank you for the info – tells me where to go looking for a suitable nut to fit the thread. I didn't fancy trying to screwcut a 7/16th left hand internal acme thread – not had enough practice yet!

Keith

[Sub MandrelParticipant @submandrel]

Didn't someone bend one of these recently?

neil

[hushParticipant @hush]

I bought the new leadscrew directly from Boxford, that was some time ago. There was a company possibly RDG( but I'me far from sure) they were offering new cross slides and other spares for boxfords. I don't have any other info. on them. A long time ago, I made a square thread tap from silver steel and used it to cut a nut for loco regulator valve, it worked but it was not very pretty.

regards ivan

[hushParticipant @hush]

Re…. the Boxford cross slide leadscrew. THE companyRDG offer LH Taps for this THREAD.Having bought one I tried it for fit In the old nut off my Machine. I hope to cut a new nut using a lump of plastic, The problem is holding the plastic for machining, time will tell! My cross slide is for a taper turning attachment and the nut is a different shape to the standard one. Another faddition to the jobs to do list How it grows as I slow

Regards Hush

[Gordon WParticipant @gordonw]

There was recently a thread on here about making leadscrew nuts, called something like "making acetal leadscrew nuts ", very interesting and may be of some use.

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