How do I set up to machine a MT2 taper?



Yea, verily! Hanging around here is just _such_ a good way to find out how much of even the basics I don't know!
Reminds me of a passage in James Michener's "Space:" "If you want to be an engineer and find you have ten thumbs, become a scientist."
I might modify it by: "If you want to be a machinist and find you have ten thumbs, become an engineer."
One or the other of which is sure to insult somebody. :)
No offense intended, gents.
John
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Andrew VK3BFA wrote:

But then you get a new problem: If your master has a different length than your work, the taper will come out wrong. With what you have, you can only continue with the swiveled top slide. But you can make things easier when you just kinda get the right angle and turn a recess inbetween the small and the big diameter.
Nick
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    Actually, he can start out with a cylindrical workpiece (turned so between centers, so it is true to the centers), set up a stop to allow the carriage to be moved between the stop itself and the stop plus a 3" gauge block (or other known length), and mount a sensitive dial indicator in the toolpost.
    Then adjust the tailstock offset until you get precisely the right offset between the two carriage positions (determined by the taper-per-inch figure for the taper you are trying to turn), and then turn the taper.
    Or -- you can toss in a sine bar and some gauge blocks to make the correct taper offset result in zero change in the indicator as the carriage moves. With that, you don't even need the known distance stops. (But for something like this, you would need something smaller than the typical 5" sine bar. I've got one 2.5" sine bar, which would work nicely for the task.
    Note that this (between centers) setup will reproduce the same taper on other workpieces *only* if the distance between centers on the workpiece remains precisely the same.
    Granted -- having a taper attachment helps a lot, but even that is tricky to get set just right. But at least you don't have to set the tailstock offset, and then re-set it to proper when you are done.
    And it really helps to have some taper gauges for both the male and the female tapers you are trying to produce. I have (so far) #1 MT, #2 MT and #3 MT taper gauges. I've got the set of reamers going #1 MT up to #5 MT, and an additional separate reamer down at #0 MT

    Hmm ... a lot of taper shanks are produced with such a reduced diameter -- but that seems to be used most often as a place to mark the size of whatever has that shank, rather than as a way to make it easier to hit the proper taper.
    Enjoy,         DoN.
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DoN. Nichols wrote:

Without doubt the best method. Aligned quickly if you have a master MT and a dial indicator. Move along the MT and adjust the taper attachments beam to get a zero-reading.
Nick, without an taper attachment
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Nick Mueller wrote:

Had another go at it today, at school. Was left to my own devices , the last day of term, as the instructors was trying to sort out all the enrollments for next year....
Found in my school textbook (yes, it was the obvious place to look....just took me a while to figure this out) the specs for the MT2 taper. Machined a piece of bar to the two start and finish diameters with the proper length between them (dont have the book in front of me at the moment), and then offset the tailstock to get the required taper.....better, but still not good enough - I was pressed for time, and set it up by manually positionining the lathe tool rather than using a dial indicator......a nice, even taper, but not good enough....sigh....will keep on persisting,
Resetting the tailstock alignment was easy - they have a test bar for this purpose....but wouldn't like to try and do it at home without much stuffing around....
And thanks Nick for the taper turning setup method - a few of the machines do have that fitting, but I didnt know how to set it up - all I had done with it so far in class exercises was to use the degree calibrations on the adjuster plate....havent got good enough at engineering concepts yet...
Andrew VK3BFA.
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Andrew VK3BFA wrote:

Didnt work. Too narrow at the opening end. Stuffed up reading the micrometer. Bugger. Try again. (and get digital readout micrometer)
Will get it right, eventually. And yes, I do stuff around - I have been fixing the sweepings of the factory floors of Asia for eons now, and sometimes, logic fails and repacking the fuse with a bolt is the ONLY way to find where the fault is.....
Electronics is relatively easy compared to this metalworking stuff - there is JUST SO MUCH that is not in any textbook I can find, and I haven't mastered enough experience or rat cunning yet to figure out things without having multiple goes at them.....(is there a bloody Secret Handshake someone shows you eventually?)
But I will persist - then do World Peace....
Re-enrolled at school today for next year - 360 course hours - hopefully will be able to get this right more often by the end of it.....
Andrew VK3BFA.
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Andrew VK3BFA wrote:

Try to get _old_ books about the subject. They describe the principles *much* better.
Nick
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Nick Mueller wrote:

I know thats good advice Nick - and thank you - still coming to terms with what some of the language used in machining means.....
had another go this afternoon, based on all the knowledge from this posting - closer, but still not good enough - getting the right taper angle is incredibly difficult, even with using a dial gauge - theres eccentricity in the test taper (or somewhere) - used the topslide but tried for a small length, only about 50mm so as to avoid moving the carriage. I feel its a combination of creeping tolerances, in my measurement/setting up/and the slop/eccentricity in the lathe...got a fair idea of how to do it better on the next attempt, but My Gawd, dont think I will ever make a living as a machinist...
BTW - I took my copy of South Bend "how to run a lathe" C1942 into school - was doing tool grinding (still havent passed it yet, but DID finish drill sharpening) - the instructors looked askance at some of the tool styles.....
Andrew VK3BFA.
Andrew VK3BFA.
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Andrew VK3BFA wrote:

<G> Find the highest point of excentricity, mark it, rotate master 180 deg. Then the middle of both readings is your zero-point. Do the same with the other end to get an (averaged) zero-reading.
Nick
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snipped-for-privacy@alphalink.com.au says...

Two things to watch for, if you haven't already figured them out.
First use a test indicator, not a plunger type indicator. The small amount of radial slop in the plunger can give you fits when probing a taper.
Second, the indicator point and your lathe tool must be mounted at precisely the same height, otherwise they'll be sweeping different tapers.
Ned Simmons
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Ned Simmons wrote:

Thanks Ned - didnt know either of those two points......
Andrew VK3BFA.
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Ned Simmons wrote:

Ned, been trying to get my head around this one....(a spirit of honest inquiry, I don't have a metalwork background so its a foreign language sometimes..and I have trouble getting my brain around some of the concepts....)
I can see the need for the dial indicator to travel in a straight line across the face of the taper - if it follows a non linear path, then, yes, it will give faulty readings. But doesn't setting it up on the topslide then moving the topslide back and forth do this anyway?, irrespective of if its in line with the tool contact point (center height) or not? - the taper is constant round the shaft, so why would it matter?
I don't have a test indicator (this need for more tooling is getting expensive, fast) - is it needed because the dial indicator doesn't have the accuracy needed to set the taper? - how much is needed over, say, a 1 inch length? - I got down to 3 thou using the dial indicator, and yes, it did bounce around a bit but got it pretty stable over the whole taper length.
And I set it up by 1.chucking a piece of center drilled bar in the 3 jaw, 2.using my live center in the tailstock, and 3.fitting the test taper piece between them, and with the dial indicator on the topslide mount, adjusting it for (virtually-well, 2 thou) no deflection as I moved the topslide handle the length of the taper. I had locked the carriage as well.
(I dont have dogs for turning between centers - I bought some at a model engineering expo recently, but the legs are too short to engage the holes in the face plate - so I need to machine up adaptors so they can, saw a picture on one of the 9 by 20 pages about how to do this...)
I can see now that I should have center drilled the bar in its final, unmoving position in the 3 jaw to ensure it was dead center - and because of the bearings in the live center, it would introduce some lateral play (cant feel any, but I realise thats not a very precise measurement method...). The tailstock offset is approx 0.05mm - the best I could get it. But it is over a shorter length than I set it up at, so any error "should" be reduced.
I am determined to work this one out.........have emailed a local engineering supply house to see if they have the blank MT2 shafts as suggested by others (But I want to do it meself...)
Regards,
Confused of Melbourne.
(Andrew VK3BFA)
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Andrew VK3BFA wrote:

Imagine traveling along the taper coplanar with the CL and then setting off more then the small diameter is. You'll get a infinite angle. :-)
Nick
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snipped-for-privacy@alphalink.com.au says...

Nick suggested imagining what happens when you deviate significantly from center height. These pages illustrate the problem...
http://mathworld.wolfram.com/ConicSection.html http://math2.org/math/algebra/conics.htm

The potential problem is not accuracy, but the slop in the indicator spindle. I just checked a couple of my dial indicators, and the spindles all have perceptible radial play. But I may have jumped to an erroneous conclusion; if the dial reading doesn't jump when you reverse direction while sweeping the taper, it probably isn't a problem for you. I got myself into trouble once trying to gage the angle of tapered surfaces with a dial indicator, but in that case the spindle was not perpendicular to the surface, and the measurements varied depending on whether spindle deflected uphill or downhill.
Re getting the indicator reading down to 3 thousandths, I think you'll need to get closer to 3 tenths (0.0003 inch) over the length of your taper before it'll start to work.
Ned Simmons
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On 25 Nov 2006 00:41:26 -0800, "Andrew VK3BFA"

One thing that most folks forget..is that with any MT.the taper doesnt need to be perfect along the entire length. May MT devices are proper at the beginning and at the other end of the object..and many are simply rebated in the center. Ive made a number of them over the years and Ive found that a .50 band at the small end, and a .50 band at the large end is often enough to hold the taper pretty well in the socket. The bigger the MT..the longer these bands should be, of course.
So if you find that the center of your taper is fat..turn it deeper so its non contacting.
Shrug..YMMV. Ive a number of such commercial tapers rebated in this fashion. Perhaps it was because its easier to make a good fit cheaply..I duna ken.
Gunner
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    [ ... ]

    Including a DRO, of course.
    There is something else non-electronic but expensive which could be damaged by this as well. The bearings in the headstock. Depending on where the arc strikes it could run the current through the "working part", through the chuck, through the spindle, through the bearings, and into the headstock and bed. If the bearings are ball or roller bearings, you have a great chance of damaging them by this current.
    I don't know what would happen with Babbitt or bronze on steel bearings. But if it welded some projections onto the steel, then the spindle would be machining out the surrounding bearing as it ran.
    Enjoy,         DoN.
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On 26 Nov 2006 01:29:48 GMT, snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote:

There must be ways of rigging a ground collector ring on the workpiece and floating the ground of either the welder output (preferably) or the lathe bed, so the welding current does not go through the lathe bearings. They weld crankshaft journals in lathes.
Don't ask me for an exact method, I've never done it or needed to. I just know that running heavy electrical currents through any normal ball bearings will ruin them real fast.
And the oil in a babbitt bearing is going to effect that the same way - you are going to have thousands of arc-across points that leave little craters in both the shaft and babbitt, and the metal particles are going to end up in the oil film.
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Andrew VK3BFA wrote:

Why bother when blank end arbors are available so cheap?
http://tinyurl.com/ygqzjo
I'm sure Blackwoods or similar have them in Oz.
Also called blank end sockets.
Tom
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