Tailstock Turret Alignment

Has anyone acquired one of these devices and had a problem with alignment.. I have just acquired one from ARC Eurotrade and found that when I put a centre in the turret it would not line up with a centre in the headstock. A phone call and a visit to ARC (yes I live close by) produced a replacement without any quibble. The problem starts with the fact that the new one does not line up either. Ian at ARC is not aware of any problems with these and is happy to offer a refund but I have decided to see whether any one else has had the same problem and might be able to offer a solution. I know I could remove the taper arbour and bore out the hole to fit a new one but it is fixed with a roll pin in a blind hole and removing that will not be easy.

I have checked the tailstock alignment and as far as I can tell it is perfectly OK.

Peter D

Peter,

First ... Wecome aboard !!

No, I don't have one of these, but I am interested to understand the problem.

Is there any way that you can check whether the error is in the position of the rotational stop, or in the dimensons of the parts? ... I think that either could cause the mis-alignment.

MichaelG.

Michael

Neither as far as I can tell.........I suspect that the problem lies in the relationship between the axis used to bore the tool mounting holes and the axis of the morse taper that fits in the tailstock. The two matching parts of the body are both stamped with the same number so some attempts has been made to create a matching pair. The problem is the same whichever hole I use to mount the centre.

Peter,

Please correct me if I have mis-understood the construction, but;

given that the rotating head sits at an angle, I think that the 'thickness of its base' would move the axis of the socket up or down with respect to the tailstock taper.

Thus; the reason for my question was to understand whether the mis-alignment is constant [high or low], or if can be corrected by very slight rotation of the 'head'.

MichaelG.

Michael

I see what you mean ...I had to sit and look at the thing for quite some time before the penny dropped.

However I am fairly certain that this is not the problem as the first one I had was consistently to one side when set with the centres point to point. The second one is consistently slightly lower. However as with all such things, supposition is one thing, the truth may well prove to be something quite different.

Peter D

Peter,

I don't have one of these but may I suggest, as a test, that you put a piece of round bar say 20mm in your chuck and machine a 16mm dia spigot on to it that matches the end of all the adaptors for the turret.
Now put the turret onto the 16mm dia you have turned (with the morse taper pointing at the tailstock,of course) and then carefully rotate the chuck, preferably by hand but slowly, and observe what is happening to the morse taper.
Does it run true? Is it a "parallel wobble or does the outboard end wobble more than the inboard end?.
This will help determine what is out of place on your turret
Bob D

Bob

I have already tried that - BUT - I can't remember the result. I put a dti on the taper.

However I will repeat the test and see what I get.

That will have to be a job for tomorrow as it is late and dark outside.

Peter D

What sort of lathe do you have ? I have a couple of tailstock turrets. A smaller one with the indexing on return and another that you manually index. The tool hole does not align dead nuts. It is a little off centre about 0.03mm 0.05mm TIR actual. Since the tailstock is actually 0.02mm above centreline , it is only about 0.01mm out, .It runs true to the axis of the quill, so have found the correct radial position that is the very best alignment. I just put a marker pen mark on the back of the unit that I sight by eye through the 2 oiler fittings on the tail stock.

Neil

Neil

The lathe is a chinese import CT-918 dated 1993/12. I have never had any problems with alignment before.

I have turned a spigot to size and fitted the turret to it. Whichever tool hole I use to fix it there is a 'wobble' or eccentricity at the end of the morse taper. Not easy to make sure that the indicator is always at the same relative position but does show somewhere in the region of +/- .3mm. That is somewhere north of 20thou. TIR. Your figure of 0.05mm equates to about 1/10th of that.

I would be happy with 2 thou.

I cant help feeling that the best (easiest) solution is to take the refund offer and use the cash to buy the materials to make my own. The immediate problem was solved by the age old method of swapping drills etc. in the tailstock chuck.

Peter D

Provided the detent is accurate enough to align all the holes with the same error perhaps you could rework the main MT arbor to fit a new one machined to fit but makes it an expensive kit. Really the finishing needs to be with it assembled but they probably thought their wonderfull CNC machines made bits that were all dead true 'cos it said so on the computer screen.

This sounds very much as if the angle of the head is wrong. I do not think there is any remedy for this as the center fixing hole will be at right angles to that surface. All this will be very hard to check with the Morse taper fitting. Personally I would take the refund offer and let the supplier take up the problem with the maker. Only then will accurate items appear for sale.

Clive

Hi Peter,

You will be best off returning the second unit back to ARC and get a refund. The first unit has been kept to one side. Once we have your second unit, we will send them off to our sub-contract engineering service provider for checking.

Clive: We have been selling this product for nearly 10 years from the same manufacturer. Over this period, we have had about six returns, mainly because of wrong hole size for the spigots - 5/8" instead of 16mm. The two units which were checked by Peter came out of a batch from which we have sold 35 units over fifteen months without any returns. If this information is difficult to believe, ARC is quite happy for Peter to check our stock-control records on his next visit. If he comes and speaks to me, I can show him. This still does not mean that there isn't a problem, but probability is low. I cannot explain why Peter has had a problem on his machine. For this reason, I will get the two units along with some units from the new batch checked. You are quite right in saying that it is ARCs responsibility to take up the problem with the maker. But, based on 10 years of sales with extremely low level of complaint for this product, ARC has to check the product before jumping to any conclusion.

Ketan at ARC.

I have to say, having subscribed to this website ever since in started, and as a satisfied customer of ARC, that Ketan's commitment to customer satisfaction is outstanding. I only wish all suppliers were as open and helpful as ARC.

Where else will you find a supplier coming back with a response to Peter like this one.

Mike

Ketan

Thanks for that - I had pretty much come to the conclusion that I would go for a refund.

I will be in touch shortly - probably next week.

This whole thing is a mystery and I will be very interested in the outcome especially if it shows the problem is at my end.

Luckily I am but 30mins by car away from ARC so any meetings will be very easy..

Once again - thanks

Peter D