Mt2 tooling adapter?

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pete
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Re: Mt2 tooling adapter?

Post by pete »

As John mentioned there almost for sure hardened. I'd think no matter where the tooling originates from if it's properly made I'd guess there's a 99.9999% chance the draw bar threads in the tooling will be hardened since unhardened would have unwanted high wear rates. The cheapest part in the tool holding chain would be that draw bar, so with proper engineering you'd want it to wear out first to save the more expensive tooling from wearing there threads out. If the tooling isn't properly made and with hardened threads you might regret buying whatever it is anyway. Fwiw due to my shops ceiling height I can't change the draw bar out on my mill if I did need a metric one without tilting the head to re/re the draw bars and then re-tramming. So essentially it's about like yours, a semi captive draw bar. I just make sure to only buy tooling with imperial threads. While that imperial threaded MT 2 tooling just isn't as easy to find now as something like R8, I have found quite a bit and bought some for my little Atlas horizontal. But I can't think of anything such as shanks for appropriately sized boring heads, collets, end mill holders etc that I haven't also seen in imperial MT 2. Prices for most of it seemed to average about what the same tooling in R8 would be at the same quality level. And if you think the more average Imperial threaded MT 2 tooling is expensive, you should see what MSC wants for one single Narex tool shank in R8 or even your MT 2.
spro
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Re: Mt2 tooling adapter?

Post by spro »

In a way, this relates to the Atlas milling machine. THAT spindle is threaded and there is a collar with pins to drive the milling arbors. Releasing an arbor is nothing. The taper is a location and doesn't require as much tension. The deformation continues to infect mill heads that rely on the locking taper and good threads.
Wolfgang
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Re: Mt2 tooling adapter?

Post by Wolfgang »

I just re-built a Bridgeport M head and put in a set of brand-new angular contact ball bearings...
During the disassembly I was impressed by the clever design of the draw bar. It is a jacking type design that pushes the M2 collet or tooling shank from the socket so that the spindle bearings are not subjected to any hammer blows to eject the tooling...
The draw bar may be removed quite easily by placing a wrench on the hexagon located just above the spindle pulley, and unscrewing the hex cap nut located on top of the splined shaft, remembering that this is a LEFT HAND THREAD!!! Note that even with the draw bar assembly removed from the spindle, the bar itself is still held captive in the cap nut by a ring screw inside the cap nut. To remove this I made a little pin wrench. The long hex nut on the top of the assembly may be removed by undoing the set screw. A woodruff key transmits the torque here.
I am faced with making an additional draw bar because my Wohlhaupter boring head has a #2 Morse taper shank that is a little too short to be pulled by the factory draw bar, and I need to make a longer one, because the M2 shank is a solid part of the boring head.
As part of the re-build I re-machined the the #2 Morse taper spindle nose; with the new bearings the run-out was still about .001". With a new DC motor and speed control I can run the spindle at 10,000 rpm! But this is a separate story.
One more thought: The end play in the draw bar is adjusted with that little internal ring screw. The cap nut MUST be screwed tightly onto the splined spindle. Failure to do this will cause the draw bar to jam.
spro
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Re: Mt2 tooling adapter?

Post by spro »

There is an issue with angular contact bearings. They can be all types of ratio -thrust to radial-loads. The MT2 spindle has a tang socket which invites MT 2 drills. Both the tang and the taper should work together. With drilling it is mostly thrust and milling, mostly radial. I think you may consider a split key above the taper. Something in the future. That is a wonderful boring head and I understand the work involved. I guess its better slipping the taper now.
Wolfgang
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Re: Mt2 tooling adapter?

Post by Wolfgang »

The M head wound up on my bench a a very reasonable cost; hence I put up with some deficiencies such as the slot above the M2 socket which requires modification of the collets... I could not determine the purpose of this slot because it is not accessible. It is located between the two bottom bearings, hidden behind the bearing spacer. On a drill spindle that slot is used to drive out the drill from the socket by means of a drift.
Permit me to reiterate: With morse taper tooling the tang is not meant to drive the tool, the taper does that very well provided it is well fitting and clean. The tang is only used to release the tool from the socket.
It so happens that with most home shop tooling sized with M1 and M2 taper shanks, that shank may drive the tooling with ill fitting sockets. With M3 tapers and larger the tang will shear off if the taper does not do the driving. I have such a "customized" taper in my possession.
Yes, angular contact ball bearings may be obtained with a variety of contact angles, and if I were repairing a production spindle I would be concerned with obtaining the correct contact angle for the application.
I priced these bearings from supply houses and they are very expensive. I got a full set of ABEC 7 grade at a quite reasonable cost from H&W. Nice people btw.
spro
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Re: Mt2 tooling adapter?

Post by spro »

I like H & W too. Their videos make rebuilding the heads a snap. I mean, it's a snap for them while I often have issues. I was buying bearings on ebay for a while. I was getting some good deals with NOS bearings and then I went to H & W site and found their rebuild kit. They imply the sealed bearings are better than the quasi- angular contact bearings of 70 years ago. They've rebuilt more Bridgeport mill heads than anyplace i know. Plus I got a new belt.
spro
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Re: Mt2 tooling adapter?

Post by spro »

goldsilence is .
spro
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Joined: Mon Feb 20, 2006 11:04 pm
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Re: Mt2 tooling adapter?

Post by spro »

Sealed bearings may prevent /cause a problem. There is still the crumbled oil pot at the top. Oil is not the cure. It was one way, then another. Oil sitting upon sealed bearings, is wrong.
Wolfgang
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Re: Mt2 tooling adapter?

Post by Wolfgang »

I kept the open unsealed/unshielded bearings, and put in a squirt of automatic transmission oil in the top oiler every time I use the machine.
The bearings I replaced were regular radial ball bearings. Their spacers pre-loaded them to eliminate any radial clearance.
Measuring the spacers I was surprised by their out-of-parallelism. A friend ground them for me to better than 50 millions in parallelism and equal height. The new bearings have the requisite pre-load built-in.
Putting in the new bearings took considerable planning because I wanted to avoid loading the bearing balls during re-assembly. The screw press my father built over 50 years ago was godsent because my arbour press was way too small for this job.
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