Tail stock advance

[robcas631]

I bought a mill attachment for my grizzly 7 x 12 lathe. I find that using the tail stock to advance material works great. Problem is I'm am not getting the accuracy I want. I was wondering if there is an insert or tool available that can be mounted to the tail stock to accurately advance my mill?

 

[Hopper]

I bought a mill attachment for my grizzly 7 x 12 lathe. I find that using the tail stock to advance material works great. Problem is I'm am not getting the accuracy I want. I was wondering if there is an insert or tool available that can be mounted to the tail stock to accurately advance my mill?

No idea of a commercial accessory but there are several traditional methods of measuring tailstock movement.

One is to use a long-travel dial-indicator to measure the tailstock quill movement.

Another is to index and mark graduations the tailstock handwheel. This can be done in the lathe, using change gears for indexing. Graduations are calculated from the knowledge of the pitch of the quill thread.

Another, but with less fine accuracy, is to mark increments on the tailstock quill by mounting it in the lathe chuck and using the knowledge of what one turn of the leadscrew equals to make equally spaced marks.

There is a lot of good info on this kind of DIY thing in an ancient book by "Duplex" (Ian Bradley and Norman Hallows) called "Lathe Devices - Their Construction and Use." Still available from Tee Publishing. (to whom I have no connection other than happy customer.)

I am not familiar with your particular machine but have to wonder why do you not use the carriage and lead screw to advance work for milling?
A handwheel on the lead screw with appropriate graduations will give very good accuracy.

 

[goldstar31]

It is difficult to visualise the problem from your description but the cheap but not nasty way to get accuracy in advancing and withdrawing your tailstock barrel is by using a cheap Chinese vernier and grinding the jaws off. Simply mount one end onto the barrel and the other end to the tailstock body- and zero and then read off your advance. That should give you perhaps plus or minus a thous and a half or better accuracy.

As you will realise, it relies on you seeing the advance - and stopping before it is too late .
A more certain way is to mount an adjustable depth stop either from the headstock or the saddle and either use vernier or blocks or even drill shanks. It's a bit old fashioned but you can make a rotating turret with appropriate bits of studding to vary the lengths.

One old worker suggested that ALL lathes should have something like this- to speed up drilling etc. I made up a similar turret years ago but discarded it in favour of one long verniers fastened to the bolt holes for the taper turning attachment and wired up to a little box of coloured lights. Pretty but no better than my earlier turret.

Does this help?

Norman

 

[robcas631]

Norman,

Yes it helps a lot! Thanks!

 

[Hopper]

It is difficult to visualise the problem from your description but the cheap but not nasty way to get accuracy in advancing and withdrawing your tailstock barrel is by using a cheap Chinese vernier and grinding the jaws off.

Doh! I'll catch up with the digital age one day. Still mucking about putting graduations on my 1936 Drummond and reading the old books from that era.

 

[goldstar31]

Doh! I'll catch up with the digital age one day. Still mucking about putting graduations on my 1936 Drummond and reading the old books from that era.

Confessions, confessions, kind sir! I had a RB Drummond and as far as I know a former neighbour and friend is still butchering wood on it.
Apart from its Number 1 Morse tapers at each end, I had only a few 16DP cogs for it. Now, I have ALL the 16DP cutters but no dear old Drummond!

As for reading old books, an old associate died fairly recently. I thought that he had had to scrap all his old copies of things. Perverse to the end, another old reprobate sent me copies.

Sadly, I now have little use in my left hand following an accident and trigger finger and arthritis in my right and am desperately trying to drive the handles with something called stepper motors. Whatever they are

If I can get this out of the way and get more time after looking after my Missus, I might get round to photographs- and posting them.

Be assured WE are not alone.

Regards

Norman

 

[robcas631]

A picture and sketch of propsed advance. What do you think?

 

[robcas631]

Sketch of idea 1.
Idea #2: I might simply insert the advance onto a chuck in the tailstock?

 

[goldstar31]

Frankly, you might get away with it but, in what I can see, I'd have driven your attachment on the saddle using the leadscrew. If you truncate your triangle of forces, your pressure exerted is not in line using the tailstock. Consequently, you are putting unnecessary strains on the underneath of the saddle- and marginally lifting it.

Again, if you follow my reasoning, you are doing exactly the same with the tailstock configuration.

Now having said all this, there is no reason why smaller things are not driven from the tailstock using a tailstock pad. Quite simply, the stresses and strains are far less.

My take, others may have different views. Mine are these very old fashioned triangles of forces from Euclid and Pythagoras- a couple of ancient old farts- like me.

Cheers

Norman

 

[robcas631]

Thanks Norman! See the post by Deverett? It makes more sense.

 

[Swifty]

Been following along on the posts, I can only assume that you don't want to rely on the divisions on the saddle hand wheel, I agree with Norman in that you will be lifting the saddle. Can you mount a plunger indicator on the bed to show movement.

Paul.

 

[Wizard69]

Been following along on the posts, I can only assume that you don't want to rely on the divisions on the saddle hand wheel, I agree with Norman in that you will be lifting the saddle. Can you mount a plunger indicator on the bed to show movement.

Paul.

I have to agree, I'm not sure where this tailstock advance idea came from but a dial indicator clamp on the ways would make more sense to me.

Edit:

Part of the reason here is that you often want to clamp the saddle in position when milling. Generally having the tailstock out of the way just makes everything easier.

 

[robcas631]

A linear force is best. My lathe does not have a break, and even if it had a clamp would apply force and lessen any linear deviations.

I'll not give up the tailstock advance because it as great applications. In the near future, I going to buy a new mill. I believe a mill handles these issues best. Till then I'll work with what I have. Thanks!

 

[robcas631]

Swifty my advance wheel has no divisions.

 

[robcas631]

A plunger indicator seems best. I've thought of mounting the mill attachment to the compound rest but that would create more problems and lack of linear movement.

I'd like to thank all involved in this topic!

 

[BaronJ]

Frankly, you might get away with it but, in what I can see, I'd have driven your attachment on the saddle using the leadscrew. If you truncate your triangle of forces, your pressure exerted is not in line using the tailstock. Consequently, you are putting unnecessary strains on the underneath of the saddle- and marginally lifting it.

Again, if you follow my reasoning, you are doing exactly the same with the tailstock configuration.

Now having said all this, there is no reason why smaller things are not driven from the tailstock using a tailstock pad. Quite simply, the stresses and strains are far less.

My take, others may have different views. Mine are these very old fashioned triangles of forces from Euclid and Pythagoras- a couple of ancient old farts- like me.

Cheers

Norman

Hi Guys,
Using Normans reasoning, the triangle of forces from either the tail stock or using the leadscrew/hand wheel would be in opposite directions. Either will create a force that tends to lift the saddle.

In reality the only difference between a lathe and a mill is that the work bed is at 90 degrees to the chuck. Milling on the lathe simply because of the much smaller table area would tend to amplify any play due to wear. Having said that I would have few qualms about using my lathe as a horizontal mill particularly for making things like gears.

 

[barnesrickw]

I mill on my taig lathe frequently. The x-travel is very limited, but it can be worked around.

 

[BaronJ]

I mill on my taig lathe frequently. The x-travel is very limited, but it can be worked around.

I agree. The lack of rigidity means smaller lighter cuts.

 

[robcas631]

What about this?
http://www.ebay.com/itm/RDGTOOLS-SM...Home_Garden_PowerTools_SM&hash=item5648d4809a

 

[barnesrickw]

I make smaller cuts, but I'm not doing production work, so I don't mind. Plus my wife is a third shifter, so I need to work quietly. Small cuts.