# Making Mt3 Chuck Holder



## taycat (Mar 26, 2015)

having learnt this week how to do a taper i would like to make a chuck holder.
need one end mt3 and other to be threaded.
found site that gives dia of each end of mt3 but not angle.
anyone tell me angle pls?
also do they need to be hardened?
have got about 10 chucks and would rather make bits myself.
thanks


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## CluelessNewB (Mar 26, 2015)

This link has what I think you want.  (Thanks to Little Machine Shop)

http://littlemachineshop.com/reference/tapers.php


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## taycat (Mar 27, 2015)

thanks for that.
if i have worked it out right that makes it 2 degrees.
going to have go next week.


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## thanvg (Mar 27, 2015)

hi there taycat,

speaking from (bitter, but not on the taper turning part) experience on a attempted MT3 collet, I would suggest not ro rely on angle settings. 
Better, mount a good MT3 taper on the lathe, put a DTI on the toolpost and dead on center height, and adjust the top-slide's angle so that the DTI's needle stays fixed for the whole length of the top slide.

I think this is the most accurate way, be it top-slide or taper-attachment that you are using to turn a cone.

(of course, a good female MT3 cone and some engineer's blue would also be helpfull for the final touches)


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## taycat (Apr 3, 2015)

did it got bit of 1" bar from scrap bin.
was a support post for hydraulic cylinder on one of machines at work before we re-furbed them.
top of pic is what i started with bottom is finished thing.
the 2 flats are for spanner to hold it when changing cylinders in its previous life.
only another 7 to do to fit all my chucks.


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## taycat (Apr 3, 2015)

not perfect by any means but for first ever go am well happy.


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## RJSakowski (Apr 3, 2015)

taycat said:


> did it got bit of 1" bar from scrap bin.
> was a support post for hydraulic cylinder on one of machines at work before we re-furbed them.
> top of pic is what i started with bottom is finished thing.
> the 2 flats are for spanner to hold it when changing cylinders in its previous life.
> ...





taycat said:


> thanks for that.
> if i have worked it out right that makes it 2 degrees.
> going to have go next week.


Taycat, A MT3 taper has an angle of  1 degree, 26 minutes, and 16 seconds  or 1.4377 degrees per side.  The taper is 1:19.902 which is .0502 inches/inch.  If I recall properly, the taper definition is in inches/inch rather than degrees.
If you are planning to use the MT3 taper to mount parts in the headstock you should use some sort of retainer to hold it in place.  Either a collar attached to the spindle or a drawbar.  A loose chuck bouncing around your shop could do serious damage.


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## w9jbc (Apr 3, 2015)

I have made chuck arbors out of old MT2 tools before they've worked out ok


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## BillWood (Apr 22, 2015)

Is the reason for doing this to prevent a stuck chuck on the threaded lathe mandrel ?

Intuitively, it appears to me that on my lathe (SB 9' clone) the threaded part is far more substantial than a taper inserted into the headstock might be - but I am a newb. at this sport.

Bill


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## janvanruth (Apr 24, 2015)

before making others check the first one out
if you dont have dikem or the likes:
take a whiteboard marker and draw lines lengthwise on the taper
insert into tailstock, twist and take out of tailstock
the lines, or rather where the lines were, will tell you the contact it makes

i fear you will find the area of contact is less than optimal....

you could releave the middle part of the taper, leaving about an inch at both ends to size
it will make getting the taper to fit easier and wont make the holding capacity much less


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## randyc (Apr 24, 2015)

I agree with Jan, your taper will probably be less than optimum.  You should follow his advice about checking fit, hand-filing and sanding as required until the fit is good.  Relieving the center section of the taper is also an excellent idea.    I also agree with Bob that you MUST have a means of securing the device to the spindle.

I don't know if the following will be useful since it wasn't designed for a lathe specifically.  The intent is to provide a means of mounting lathe chucks to the spindle of a horizontal mill as well as a faceplate (to which the chucks are mounted).  The mill can then be used as a lathe.

The reason is to increase swing capability - even a small horizontal mill can swing huge diameters compared to small lathes, when the over-arm is cranked back out of the way.  Longer workpieces, if within the over-arm envelope, can be well-supported by using the over-arm as a tailstock and mounting a center in place of the end bearing.

Note that the tapered shank is threaded for a retaining bar.  Also note that the faceplate can accommodate two different chucks, which you might also want to consider.  The reason is that most larger chucks are rated at modest RPM while the smaller chucks can be spun up to much higher speeds.

One more point when considering mounting your chuck is to keep it as concentric as possible to the spindle axis.  Out-of-balance situations can be dangerous as well as putting more load on the front spindle bearings than one might want.

That's equally applicable when securing odd-shaped work in a 4-jaw chuck or on a faceplate.  Good practice suggests running the spindle much slower than normal if the work cannot be counter-balanced somehow.


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## janvanruth (Apr 25, 2015)

the op didnt say but i assume he is talking about drill chucks
other than for use in a mill, like randyc suggested, mounting a chuck on a threaded arbor to be used in the spindle of a lathe is  impossible
it would never run with the accuracy needed in a chuck

i did make an mt3 arbor with a faceplate welded to it for my mill 
just welded heavy steel plate to the mt3 arbor and turned it in the mill 
just like adapting a backplate to a chuck in the lathe


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## randyc (Apr 25, 2015)

janvanruth said:


> the op didnt say but i assume he is talking about drill chucks...



Oh yes, I think that you're correct - somehow I managed to skim over the photo with the threaded stub on the MT arbor.  Had I been perceptive enough to realize that the OP wanted to mount a threaded drill chuck I would have recommended a method like this one:

http://www.hobby-machinist.com/threads/improving-drill-chuck-accuracy.32555/


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## Bill C. (Apr 25, 2015)

I seem to recall using a indicator to quickly off-set the tailstock using a good taper.  One shop I worked in had made a tapered arbor.  I has assigned the task of grinding the taper to check my progress I used Prussian Blue.  I remember putting thin coats in three or four stripes. Then pressing the arbor into the milling machine checking so see if there was Blue transferred.  If so I knew I had the angle correct.  I never felt comfortable setting up a cylindrical grinder since the pivot point was not in center of the part.


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## taycat (Apr 26, 2015)

thanks for info.
was for drill chucks sorry should said originally.
have done 3 and all work fine.


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## kingmt01 (May 5, 2015)

Thanks. I need to do the same as taycat. I have two chicks needing arbors. I stole my chuck from my mini lathe for my Mill. The mini lathe has a MT#2 the 14x40 uses a MT#3 & the mill uses R8. I can't bring myself to remove the chuck from the arbor again after getting it lined up but I have these two screw on chucks without arbors.


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## cathead (Jan 31, 2016)

I would:      Machine the taper, apply dykem, check the fit, make a second light cut after slight angle adjustment, check fit, etc. 

It all boils down to fine work getting as close a fit as possible.  Sometimes light filing is all it takes to see a better fit.   Leave the part 
a little oversize so you have enough metal to make several light cuts.  It's the surface area that gives the holding power.
Hardening the taper might introduce warpage so I leave mine as machined.


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## TC0853 (Feb 15, 2016)

thanvg said:


> hi there taycat,
> 
> speaking from (bitter, but not on the taper turning part) experience on a attempted MT3 collet, I would suggest not ro rely on angle settings.
> Better, mount a good MT3 taper on the lathe, put a DTI on the toolpost and dead on center height, and adjust the top-slide's angle so that the DTI's needle stays fixed for the whole length of the top slide.
> ...


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## bfd (Oct 17, 2016)

the  easiest way to get the taper as close to right as possible is to get an existing 3mt tool and mount it in your chuck and indicate it in (4 jaw) set the other in in a center live or dead and mounting an indicator on the toolpost  with the button directly on center ( I assume you are going to use your compound to do the angle then move the compound back and forth until you get as close to your angle set.(0) on your indicator. always take your reading from tailstock to headstock, moving your indicator all the way off the part each time. you do the same thing if you are using a taper attachment. same if you are trying to offset the tailstock. this get it real close then leaving .002 0r .003 oversize blue it and check fit to a factory taper sleeve. polish  until you get a 90% to 100% blue contact. don't forget to undercut thetang end to aid removal. then If your lathe has a taper headstock then with sleeves mount your new part in t
he headstock drill and tap a 1/2"-20 hole and  Loctite in a sHort piece of threaded stock and you have a threaded chuck adapter. if you intend to possible run the chuck backward then you will want yo drill and tap a 1/4"-20 holeinthe center if the threaded stock and lock the chuck in place. vsr drills do this with a left handed bolt. you might not hace to do thar if you ignore the 1/4"-20 and change it to a 1/4"-28 these different pitches will also lock themselves in due to different pitches nuf said bill


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