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03-20-2017, 03:03 PM #1
between centers - collet required?
For between centers work I normally put a center in the three jaw and true it up and drive the dog off the chuck jaws. But I often see pictures like this:
And I was wondering how the center is held. Is it a taper match into the spindle? Or otherwise?
I've not seen any SB 'special MT3' taper centers floating about. I have done it using a collet to hold the center but the setup is a little annoying - and my collet holder handle is way too big and unbalanced to spin at any speed (shop made I suspect)
03-20-2017, 03:43 PM #2
- adaptor, "wotever" spindle taper - a shortened 12 Jarno for the 10EE - to one if not two choices of MT tapers.
- full-spindle taper "plug" with reduced centre formed right onto it. MAY (or may NOT) take less space. Harder to heat-treat accurately. More costly to swap for new, or have re-ground, but it isn't the HS centre as wears by much anyway. Not moving by anything more than slop in the driving dog, if even that. See old-style rawhide ski-boot laces.
TS centre is the one as has to deal with the wear and overheat damage.
You should just MAKE an adapter slug to something appropriate to the lathe's capacity that can take a cheap and common MT centre. That may as well be the same as wotever your TS is, ELSE but one size up or down.
The adapter is a relatively minor PITA to make, blue, and fit properly, but even if not hardened, should last a lifetime if not abused, even if the centres do not, quite.
I'd suggest a relieved shoulder, wide chamfer, fat curve, or some combination of the above on the arse-end of such a plug - OD AND ID - so that even if.. your knockout bar raises a bump now and then near either edge, the scar won't contact either taper.
03-20-2017, 05:13 PM #3
You won't find any special SB MT3 centers because there are not any.
There is an adapter sleeve that takes a standard MT2 center.
the spindle taper itself is made to the taper of MT3 BUT a bigger gage line, meaning the taper is the same spec( taper per ft or inch) but it is physically larger than a standard MT3
Ted probably has a sleeve.
Monarchist liked this post
03-20-2017, 05:16 PM #4
Your lathe would have shipped originally with a reducer, which matches the taper of the spindle on the OD. The ID is a Morse taper, which usually is the same size as that used in the lathe's tailstock. You could certainly make one, or even a one-piece center that fits the bore.
03-20-2017, 07:43 PM #5
03-20-2017, 07:59 PM #6
If you want the taper dimensions, I actually made the measurements on my 10L a while ago with the intent of making a direct fit center, or maybe making an adapter. I don't have a drive plate currently, so it hasn't been much of a priority. You can check it yourself easy enough, just need a dial indicator to monitor travel on the carriage and a test indicator to measure inside the bore as you go. I took notes on the taper at 1/2" and 1" depth at 90 degree intervals around the spindle, repeated 3x for each position to make sure it was consistent. Its tedious, but certainly not difficult.
03-21-2017, 04:44 AM #7
tobnpr: interesting. You use an MT3, Allan's link shows it was an MT2 actually.
But, cool. Look like if you want that setup to happen create yourself an adapter that goes from the large SB 'MT3' taper to either an MT2 or MT3 dead center.
That makes a lot of sense. But before I can cut a long accurate taper I need to re-align an re-babitt the taper attachment ... but that is another story!
Thanks again all. Very helpful.
03-21-2017, 04:58 AM #8
You could make that adaptor with the compound, as long as it has enough travel. YouTube and Mrpete could be a good resource. Tedious, but very doable.
03-21-2017, 05:24 AM #9
03-21-2017, 05:34 AM #10
Bore-wise, its closer to an MT5, but the taper is MT3.
03-21-2017, 03:16 PM #11
Yep. The specs show is as large diameter just a hair over 1 5/8" with an 0.602" taper per foot - which is MT3. Another little learning project for me I think. :-)
03-23-2017, 05:17 PM #12
03-23-2017, 06:01 PM #13
Legend! Thank you. I was looking for that web site and I just couldn't remember the name. I was actually looking for the chuck stop. I didn't realise they did the adapter.
Thanks again, much appreciated..