Thread: mt3 problem

All my CTC mt3 stuff works fine in both ends (oh thats wrong) of my little lathe. Actually i have to put a bolt on the thread at the end of my collet chucks so i can eject them. As i use them in the head too i need to take the bolt out to put a drawbar in.
Can you take a pic of the problem one up against a good one?

Edit.....the sun just came up....short of what J&H suggests, the only thing you can do is cut the front off the TS quill....not really an option IMHO!
Otherwise buy one from a different source, or make one up yourself.

Assuming that the arbor is threaded onto the boring head, you could perhaps just turn up a threaded extension to go between arbor and boring head, same diameter as the major diameter of the MT3?

I have the same problem with some of mine. I just place my tailstock wrench between the arbor mounted (whatever it is) and crank the wheel back and it pops right out...Bob

Does your other M/T 3 tooling fit the Headstock without a problem.

Are the lengths of your other M/T 3 tooling the same length as this Boring Head taper.

Have you measured the large diameter of your other M/T 3 tapers and compared this to your Boring Head taper.

Place some of your other M/T 3 tapers in the Headstock and mark with pencil where they stop then do the same with the Boring Head and compare.

Cut some off the small end of that arbour, that makes the arbour a larger diameter then...

Of course cut too much off and then you will never eject it..

What sort of lathe is it.... Some have a tang slot milled into the tailstock quill..

Thank you ,Ueee,Jekyll and Hyde, aametlemaster,{i[e Clay,and .RC, I had thought about shortening the quill ,but thought that if it didn't do the job I couldn't put it back againI have taken some photo's ,but beats me how to get them into the forum now,,so I
will try and explain ,

The boring bar has a separate arbor which screw's into the back of the head piece,the largest point of the MT3 is to small ,to fit properly in the tail stock, or in other words it is a very loose fit,when up tight to the head piece to the tail stock quill,

All the other MT3 tools are much larger and there is no problem with any of them ,

My lathe as I mentioned is a Herless 11 b u k, Bought in 1989 new, has a Mt5 spindle to the head stock , the sleeve to bring it down to Mt3 ,will just allow the boring bar to fit and only just I might add, the photo's I took would give you all a clear picture but I can not see now, how to up load them to my library let alone put them in to this reply,

There is aprox 3/16th of an inch at the quill end that is clear of the measuring area,and I suppose if I took an exact measure of the boring bar MT3 large end, to see if that would work out,and the largest point in the quill 3/16th inch in,,I went out and measured it there is only 14 thou to play with and I am sure you all will say not enough to take a chance an cut the quill.

So I am wondering what's the best thing to do ,the arbor thread is 1/1/2 inch x18tpi, would cutting there MT3 part off and
boring and tapping a new bar on then cutting a new MT3 to suit what I have be the away to go,open to suggestions ,I have just gone back to car restoring and would love to sort this problem so that I can use it thank you all.
.RC most of the MT3s have a tang and those that dont I use a distance piece to eject them .

Originally Posted by TKO

{i[e Clay,and .RC, I had thought about shortening the quill ,but thought that if it didn't do the job I couldn't put it back again.

I suggest cutting the end off your arbour, not the tailstock quill...

The problem from where I see it is simply the morse taper arbour you bought is just too long.. It is hitting up inside the tailstock quill...

I am betting your lathe tailstock quill deep inside has an actual slot cut in it so it really looks like a female version of a proper morse taper shank. it is to stop the risk of any tool put in there from coming loose and spinning damaging the bore..

Your boring head shank, has no tang and I bet the tapered portion is longer then a standard more taper drill arbour... As such when you put it in, it is hitting up against that tang slot in the quill before it fits properly...

Here is a photo of a morse taper boring head arbour I made years ago... What you will need to do as shown in the photo's is shorten the end of the arbour a small amount... If you put that in as is, you will never be able to eject it (unless you also have an ejection slot in the quill you put a wedge in to knock it out)... A short bit of threaded rod cut as shown i the photo will act as a tang on a normal morse taper arbour.

I have managed to upload a couple of pics006.jpgboring bar arbor removed


001.jpgcomparison of other bars can't get the pics I wont to show need more practice, because the memory is very short sorry,what I mean is I should write the method down but by the time I have reached for the writing gear memory has gone
so tha'ts my story .I will try again for the other pics.

What you are saying RC is what i thought to start with, but i think the shoulder i have marked in your pic is hitting the front of the quill.

TKO, I would make a new one. If you turn the taper first you can put it in the headstock and then do the rest of the work, that way it will be as concentric as possible.
There is a thread in the Forum helpdesk section on posting pics.

Edit, Why not just try and machine a bit off the back of the arbor, the bit that is hitting the quill?

Oh OK, it is hitting the other end....

That is easily fixed.... Take some off the other end... Probably need a carbide tool as it will be hardened a tiny bit...

The arbor MT3 is shorter than any other Mt3 that I have got ,it does not reach the full length of the quill it goes all the way into the quill and the quill is tight up to the back of the boring head and the arbor slops about it is not the same size at its larger end I have measured both the inside of the quill and the outside of the boring bar arbor and the boring bar is small ,I hope I am not confusing any body with the problem ,but the boring bar is to small for the tail stock quill, if you cut the threaded portion off it would still not fit as it would go to far in to the quill, I appreciate the comments given ,I just wish I could get the photos in that way you will see the problem.

As I mentioned before, using it in the reducing sleeve in the head stock it is only just doing the job nothing to spare.
Still trying for pics.

Well one more for the road ,the buckets has not got the pics as well ,but this i the problem,

What RC and i were saying is machine it off like in the pic. You don't have to follow the taper, just cut it straight from the relief groove. You will probably need carbide to do it.

Is the morse taper in the quill set back from the quill face a bit?

Sounds a bit that way to me.

Rob