Turning an MT2 internal taper

[Brian Rupnow]

I have a lathe and mill which both came stock with MT2 tapers in the headstock of the mill and the tailstock of the lathe. I want to make a piece of tooling with an MT2 internal taper, which if I succeed will eventually hold my boring head, possibly to make a ball turner. The first trick I have to master of course, is to be able to set my topslide over to the precise angle of an MT2 taper. I don't really have to know what that angle is---I just have to precisely match it. I do have an adapter which I purchased for something, which has one end turned to a true diameter, with an external MT2 taper on the shank. I chucked up the true diameter portion, and then made an adapter from a piece of 1/2" thick aluminum which I could hold in one of the toolholders for my AXA toolpost and clamp the shank of my dial indicator in. With the height of the dial indicator set exactly on the centerline of the lathe chuck axis, I endeavoured to get the topslide angle perfectly aligned with the shank of the MT2 part, so that by cranking the topslide in and out over its full travel of about 3" I would get no deviation in the reading of the dial indicator. This was not an easy thing to do. I would be ashamed to tell you how many times I had to adjust it and tap it this way and that way until I ended up with no dial indicator movement over the full travel. However, I finally reached that "o" movement of the dial indicator.--More to follow.

 

[Brian Rupnow]

Oh Stupid me!!! I got the angle set perfectly. As John Hobdeclip pointed out, the damn hole got bigger as I bored it deeper. Aaaarrrrggghhhhh!! Oh well--it got me through a wet nasty afternoon. Yes, you are probably all correct, and I can probably purchase a straight shank, but this was simply a "see if I can" exercise. However, as Jaakko points out, since I haven't changed the setting of the topslide, maybe I can reverse the lathe and bore on the opposite side of the hole. I will have to think about that one. I still have a piece of 1.25 inch aluminum that I haven`t messed with yet, long enough to run this exercise over again.

 

[Brian Rupnow]

OKAY---We have success. Started with a new piece of aluminum, turned the boring bar over 180 degrees, did NOT run the lathe in reverse, but bored on the far side of the hole. worked perfect!! There is a 3/8" thru hole for a drawbar bolt which will firmly pull the boring head into the taper. I'm not worried about concentricity, because if I use this thing as a ball turner, it will only be rotating 180 degrees at most. Now that I have succeeded in what I was attempting to do, this thread is probably going to morph into a ball turner thread. I had built Steve Bedair's ball turner about 5 years ago, but was never happy with it and ended up giving it away.

 

[Fabrickator]

Brian

It sounds like you figured it out, but in the future you may want to go LMS website and find the chart they have for all of the Morse Taper specs. Nice thing to add to your files.

Rick

 

[jack.39]

As I understand it, FWIW, precise matching of tapers is difficult, and usually accomplished using precision ground masters, both internal and external. The final cutting is done using Prussian blue, and may require many very light cuts.

That was the traditional way. Today's technology might, for all I know, actually provide means of matching the actual angle involved. I'm of the old school, however. jack

 

[goldstar31]

I can understand and appreciate the efforts in going to get a Morse Taper made.
As has been said, the use of precision ground masters is to be commended.
I tend to buy soft blanks now- I'm old, lazy and really haven't the time left but friends still borrow my finishing reamer. Sadly, the roughing reamer has not returned.
Two more points arise. Somewhere in the clutter which I lovingly call my workshop is a set of notes where Martin Cleeve made a peg to ensure that future repeats when he used his top slide. It must have been a 'once and for all' state of mind.
The second is from another old friend- we competed in white water kayaks, dinghies and generally messed about bobbing up and down 7 miles out to sea! Colin had an old Myford ML7 which ironically lived under his bed. He cast a taper turning attachment from alloy pistons in the back yard and being mathematically with it, used it as a development of a 10" sinebar that slid the saddle along.
It was all very logical because Mr Morse seems to used something similar. All that was needed was to offset the 10" bar by a quarter of an inch- and that was it. I have a 5" bar and a set of J blocks and each seems right. Somewhere, somehow, They got it wrong!
Given the same problem, I would use the Clarkson or my little Stent to grind a sort of D Bit from 'silver steel'/drill rod to finish bore but I would make a stepped plug gauge to check my earlier boring.

Regards

 

[Tin Falcon]

IIRC external tapers are normally turned and ground. internals are reamed. that said the south bend has an exercise for students to make taper gages.
Tin

 

[Brian Rupnow]

So---The arbor is finished, with an MT2 internal taper, a 1" outer diameter, and a 3/8" thru hole for a drawbolt.

 

[MachineTom]

Funny that you posted this as yesterday I cut a MT-2 for a new quill in the DR-10 tailstock. A tapered bore cut with the lathe, and a reamer for the last.010. A trick when cutting bores that I often use is to touch the boring bar to the face of the work, set at a diameter of .010 less than the final size. So in the case of an MT-2 major diameter of .700, touch ring of .690 Ring, when ring is cut its time for the reamer. You should mark the reamer for the final depth, or have a way to accurately measure the depth of the cut. At 2.656" its not that easy to measure. Not all applications will need that level of accuracy but there are times when you do.

Nice job Brian, Those are a simple way to make a Radius Cutter, I will consider the same thing. What sort of grind is done to the tool?

 

[Brian Rupnow]

Tom, I haven't even thought to much about the actual tool yet. I am busy today making the rest of the parts for the ball turner, and taking pictures of my progress as I go along. I don't want to post anything until I see if it works or not. I don't mind making a mistake and having the whole world know about it--we all make mistakes occasionally. Its just that I don't want to be seen as a complete fool, so I will finish the ball turner and make sure it works before I post about it. I think a tool with a 1/8" radius would be the best, because you end up cutting on both sides of the tool as you swing the handle back and forth----I think!!!---Brian