MT4 Adapter spun in spindle, how do I clean up the spindle taper?

[woodchucker]

No drawbar on a lathe, just the thunk when it seats.

Usually in tailstock the pressure from drilling seats it fine as log as tooling is of correct size.

Sometimes we get crazy and a little help needed.

The old days they has cross bar supports for reducing spinning of tailstock supported tooling.

The chuck key for Jacobs chuck does well, the rod of the key fits the holes so you can support the chuck.

This is a 3.5 inch hole through 1.25 thick plate from scrapyard.

Chuck key is resting on OCTP, cutting at maybe 60 rpm, VFD are handy.

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I actually have a drawbar for my MT3 in my lathe spindle. When I was using a milling adapter on the lathe, before I had a mill. I bought an MT3 to 3/8 or 1/2 endmill weldon. It fit well, but the side cutting pushed it out of the bore. It's not a Chineese unit, it's either Israeli or German, can't remember.. I had to add a drawbar to keep it in.
edit: It's made by ETM

@tq60 nice lathe, what is it? Also, before you turned the outside of the flame cut, I assume you ground it with an angle grinder? I tried without on one piece and just went through lots of carbide.. The next one I ground and it was a cake walk by comparison.

 

[Jim F]

The MT in the spindle is for holding a "dead" live center when turning between centers, not for holding work, unless a drawbar is used.

 

[RJSakowski]

The MT adapter could be used for turning without a drawbar, providing the work was also supported with a tailstock center. A live center would be preferred as you can use a higher preload. I made a tool for tailstock alignment based on one made by Mr. Pete

from an MT3 -JT3 adapter by turning the JT3 portion to a straight shaft using this approach. (Interesting to note tha Mr Pete doesn't use a drawbar when he is turning his tools.)

If a drawbar is used it would have to pass through the MT4 adapter to the MT2 taper to avoid having the same problem with the MT2 taper spinning in the the MT4 adapter.

 

[Jim F]

The MT adapter could be used for turning without a drawbar, providing the work was also supported with a tailstock center. A live center would be preferred as you can use a higher preload. I made a tool for tailstock alignment based on one made by Mr. Pete

from an MT3 -JT3 adapter by turning the JT3 portion to a straight shaft using this approach. (Interesting to note tha Mr Pete doesn't use a drawbar when he is turning his tools.)

If a drawbar is used it would have to pass through the MT4 adapter to the MT2 taper to avoid having the same problem with the MT2 taper spinning in the the MT4 adapter.

your tail support is acting as a drawbar, providing side support.

 

[tq60]

I actually have a drawbar for my MT3 in my lathe spindle. When I was using a milling adapter on the lathe, before I had a mill. I bought an MT3 to 3/8 or 1/2 endmill weldon. It fit well, but the side cutting pushed it out of the bore. It's not a Chineese unit, it's either Israeli or German, can't remember.. I had to add a drawbar to keep it in.

@tq60 nice lathe, what is it? Also, before you turned the outside of the flame cut, I assume you ground it with an angle grinder? I tried without on one piece and just went through lots of carbide.. The next one I ground and it was a cake walk by comparison.

No grinding, just used brazed carbide.

Gripped from inside after slug fell out.

Lathe is SB 14.5 with an old belt that slips badly, have not got around to replacing yet so light cuts.

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[gard]

No grinding, just used brazed carbide.

Gripped from inside after slug fell out.

Lathe is SB 14.5 with an old belt that slips badly, have not got around to replacing yet so light cuts.

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How long did it take to cut out that slug with the holesaw? I made some similar holes awhile back by boring it out and it seemed like it took forever.

I also made a drawbar for the SB 14 1/2 lathe, have held a boring head in there and also use it when turning brake rotors. Bought some MT3 collets but dont think I have used them for anything yet.

I am repairing an old drill press that has a threaded hole in the side, about 1/2 way up the MT2 socket, I have never seen that before, it there any valid use for it?

 

[tq60]

Not as long as you would think.

Maybe 30 minutes tops.

We kept speed slow and minimal heat buildup.

Slug came out a bit warm but part and saw not so much.

We were in no hurry so no tooling was damaged.

Also no need for pilot drill so not used.

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[WobblyHand]

Cleaned up the spindle with some round stones. At least the rough stuff is gone. Searched for my MT4 dead center, and couldn't find it. . I thought I had one when I bought it. Found an "MT4" dead center that I bought. Another never been used tool. Did the smurf thing, tapped the dead center into the spindle and then popped it out. More or less what I expected. Nearly 0 contact. Just the ring around the spindle nose. There was a small amount of contact at the base, but overall total contact maybe 5%. The missing blue in the second picture is not because of contact, it was because I didn't apply the blue to the very end.

From the marks on the spindle and on the morse taper sleeve earlier I suspected that these bits of tooling are off spec. The taper is not MT4, it is steeper than MT4. Looking carefully at the dead center, the external packaging says MT4. On the actual dead center it is marked MS4. Is this some unknown Chinese standard? I can't find any reference to a MS taper. Maybe it stands for morse sleeve? But a dead center is NOT a morse sleeve. Either way, the dead center I have has little contact along the sleeve. Instead, all the forces are concentrated at the very taper edge at the spindle nose.

I will clean up the morse taper sleeve (MT4 to MT2) to do the blue check. Bet it will have similar (nonexistent) contact.

Disappointed in this. Why would someone make a MT that wasn't really a MT? This was nicely ground, can't imagine any meaningful manufacturing economy. Have to think these were (both) rejects, scooped up and resold as compliant.

 

[Dabbler]

Youm could find a MT4m finish reamer and bring it to spec?

 

[SLK001]

Just a quick question: Is the spindle taper a short taper? I mean, does it have an MT#4 taper slope, but it is only 2-1/2 to 3" deep? A MT#4 has a small end diameter of 1.02", but your bore is only 25mm (or less than 1"). Your spindle taper has to be at least 4.0625" deep to fully engage a standard MT#4 plug. Time to start "fingering" your baby!