Tailstock indexing

Brought a book the model engineer vol.100 jan - june 1949 ,and am reading my way through it an laughing at the ads for the prices then ,but have found a bit about making a indexing dial for the tailstock,has any one made one of them ,l seem to get trouble drilling holes to the right depth ,and in the book say that you can get the depth dead accurate,he worked out for the gradutions by the thread on the barrel being 1/8" pitch then 125 divisions = 1 division being 1 thou,perhaps one of you clever people can say what l would need for the ml7 ie divisions.

john

If it is 1/8” pitch, then a single turn will be 1/8”. What accuracy do you want and how good is your counting? It’s not rocket science to get quite close on depth.

See:

https://www.model-engineer.co.uk/forums/postings.asp?th=140386

where a graduated Myford LEADSCREW handwheel is repurposed for use on the tailstock.

I can't say I've ever found the need to be "dead accurate' with a drill. Dead accurate to where? The tip? .... is that useful? The full dia?... does the tip-to-full-bore distance vary from drill to drill? Especially after grinding the drill.

I've always found the native ML7 tailstock scale adequate for my needs - although other peoples' mileage may vary.

Edited By Bandersnatch on 25/11/2019 01:02:00

Thanks bandersnatch l agree am quite happy with the scale on my southbend ,but there is no scale on my myfords tailstock barrel ,so that has always been a problem,mybe l should try an get a a s/h barrel for it,but that can wait till l have got a degree in rocket science.

Easy enough to make your own scale markings on the tail stock. Hold the tailstock barrel in the lathe's chuck and use a sharp pointed tool bit held in the toolpost to inscribe each line a few thou deep. Use the leadscrew or even the topslide to advance the tool bit 1/8" for each new mark. You could even rig up some stops to limit chuck rotation.

The other thing that is easy to do is count the number of turns of the tailstock handwheel used when drilling a hole. We know that one turn equals .125" because it is an 8tpi thread. So half a turn is .062" and quarter of a turn is .032" . Or 1/8", 1/16" and 1/32" respectively. You can even get pretty close with one eighth of a turn that moves the drill 1/64" or .015".

That's plenty close enough for most drilling work.

Or you could use the old dodge of adding a clamp to the tailstock barrel to hold a standard 6" ruler and drill and tap a pointer into the tailstock body.

Only yesterday while working on quite a complex engine piston I had the need to be quite accurate with a flat bottomed hole so set the tailstock dial to zero when the tip of the drill was touching and got the required 0.688" depth and also used it or the subsequent drills and D bit.

There is quite often the need for small recesses of a specific depth cut with a D bit or milling cutter maybe more so than just a plain drilled hole.

Has Graham Meeke done one for the ML7? seem to remember one for the S7

My take on this is an Aldi digital calliper at around £9 modified to make a tailstock readout. No more counting turns and can be set with a slip gauge if required.

If you search U tube with the words "Tailstock DRO" there are plenty of ideas on how to make a quite accurate depth indicator

.

Just an aside: Does anyone remember the the tool that Myford [Beeston] used, to scribe the scale divisions ?

... Rather clever, I thought.

MichaelG.

No, but I hope you will tell us!

Were the lines rolled in rather than inscribed? The latter process is well described by Len Mason in Using the Small Lathe.

No, but I'm now wanting to find out how they did it, when five minutes ago it had never crossed my mind !

Not sure if I have a photo anywhere ... but I do remember being impressed when I saw it.

They used a lathe bed, with leadscrews fitted front and rear [one Imperial, one Metric]
The scriber swung up and over the tailstock barrel.

Just a clever piece of manual tooling, made largely from stock components.

MichaelG.

Hi Jason,

My thoughts on the ML7 Tailstock set-up' was always to adapt the tailstock to take a Super 7 Tailstock Barrel, Feedscrew, Thrust bearing and Handwheel. Which I considered an easy thing to do with the aid of an adaptor piece. The S7 set-up gives a much more sensitive feel when drilling over the ML7, (having used both). With the added bonus of a self ejecting facility for the Morse taper tooling. I always found the Acme thread sticking out of the ML7/ML10 Handwheel a constant source of numerous cuts.

This conversion was one of the things I wanted to do on the ML10 that I once owned. The substitution would then allow the fitment of the S7 Tailstock Dial that I designed a while back, which would be an integral part of the adaptor piece.

Such a conversion now would require access to an ML7/ML10 to formulate the design, but this is not currently possible hence why I have not proceeded further.

Regards

Gray,

Generally,

I hasten to add that I know in some peoples eyes this modification to the ML7 would be a retrograde move, possibly treasonous, but as with all things in life we make choices based on our own requirements.

Regards

Gray,

Edited By Graham Meek on 25/11/2019 11:37:28

Here’s my dead simple tailstock measuring device.

sorry it’s upside down.

Uses a simple terry clip, a bit of case binding steel strip as it’s springy and a 4 ba bolt with 3 nuts. Just file a notch and a point in the strip. The ruler enables both metric and imperial by just rotating the lot. Normally stored in the lathe tool drawer . I like to think the resolution is as good as I can mark out with a rule and scribing block, so very good!

one day I will machine a placement for a pair of pillars to get rid of the spring in the ruler .  I would love to find a ruler which is graduated from the right or even mount the plastic digital calliper I bought years ago but this solution is so simple and there’s more interesting things to do! The tape gets sticky and needles replacing every 3-4 years.....  in use just move the point to a suitable starting place and work to the depth you need.  So so simple, but nothing like the highly elegant solution Graham Meek will provide us with!

Edited By Zan on 25/11/2019 15:04:53

Edited By JasonB on 25/11/2019 15:06:04

Thanks hopper ,my barrel now has a scale,likie you said simple to do.

You're welcome.

Well done!

This thread came to mind when I was looking at the lever-operated tailstock on my Super Seven. With the lever retracted, the exposed end of the ram could easily be calibrated with, say, metric divisions to complement the calibrations on the other end.

The lever setup may also be more amenable to the caliper DRO approach.

My version of tailstock DRO ... just a tyre depth gauge modified by having a small collar & neodymium magnet epoxied on & a small steel plate epoxied to the aluminium collar on the ram, works just fine for depth drilling. It is held on to the tailstock body by more magnets epoxied on the back of the gauge.

George.

Edited By mechman48 on 26/11/2019 14:51:54

Mechman, That’s what I intended to do, but your tailstock is flat topped , the old design of the S7 makes the mounting a lot more difficult and would need the casting to be drilled and/or a flat machining at the correct angle