regrinding machine centers

[michiganbuck]

I just answered a private message with this..If any PM Members have something to add please do so.
Buck
At the big shop, I used a bar with it having a double precision bearing to intersect the taper at two places so acting like a floating steady. I could grind a center point off the taper to a few millionths of dead on center..But the setup was not very safe so I don't recommend anyone doing the same. Set on a brass or bronze double would be much the same.
Your Studer S20 should have a #4 in the headstock so I would purchase a #4 to #2 Morse taper and just grind your points out of the headstock by turning the headstock to angle., perhaps using a lathe fish gauge for an angle template. Good to have/use a Norton center lap point mounted wheel to lap your part center before setting them on your machine center so to have less wear on machine centers..
One can rough grind parts on a live center, then finish grinding them on a dead center, perhaps buy a Royal live center(or the like) if 50 millionths to one-tenth would be close enough. A common live center with ,0002 error you can expect .0004 on your parts so such belongs in the dumpster.
Let me know if this was helpful, Buck

 

[ballen]

Probably off topic, but for the record...

Your Studer S20 should have a #4 in the headstock

I think an S20 is the same as my Studer RHU-450, meaning it has a short MT5 in the workhead.

 

[michiganbuck]

The private messenger replied that his older Studer has a #2m on both head and tail.
my reply is below.. anyone wish to input, feel free.

Tom
Is there a reason that you can't place a machine center in the headstock #2 taper , turn the headstock to a number that will give you a 60 on the point, and then grid it?

Another common procedure is to dress a wheel to an angle that will produce a 60 on your machine center by cross-feeding straight into the part/center. Yes that dressing wastes a lot of your wheel.

Another common practice is to turn the wheel head to the needed angle.

A third option may be to buy new centers and when you have accumulated a dozen send them out to a local grind shop to have them re-pointed.
Buck

looks like new and new carbide-tipped imports with free shipping for $10. How can that be except that our giving free shipping on imports? Nothing is free so we are subsiding foreign products and shipping..

 

[michiganbuck]

The private messenger states that his vintage Studer S20 only has a dead center in the headstock, Is that true for a vintage Studer?
Did they make a machine with only a dead center, or perhaps the fellow does not know to unlock the rotation?
Please advise if anyone can give information.

This seems an older Studer grinder, and it seems to have a rotating headstock center.

 

[M.B. Naegle]

ballen's mention of a short MT5 has me thinking....

I have an an old lathe (1910's Flather) that I found the headstock and tailstock tapers to be Morse #4, but standard centers and tools project out more than usual. In my stash I found a "stubby" MT4 dead center that's a perfect fit as it's about 1" shorter than a typical MT4 dead center. Is there a name for such a center, or did they have a more common use? Can they be bought anywhere, or is it better to make my own or regrind an old damaged center to be shorter?

 

[ballen]

Buck, the machine shown in your post #5 is a Studer RHU-450, which is the same machine that I have. The workhead has a short MT5 taper. If you put a normal MT5 in, that normal MT5 fits OK but projects about 40 mm out, just like what is shown in the video in post #5. I thought that a Studer S20 had the same short MT5 taper.

[EDIT]
I just had a look online. Buck, you were right all along, and I was wrong. Sorry for throwing this off track.

According to this brochure https://cdn.studer.com/fileadmin/co...chures/englisch/s20-brochure_studer_en_02.pdf the workhead of a Studer S20 is MT4, see below under "Universal Workhead".

 

[michiganbuck]

Bruce, Does your headstock have the ability to rotate like a spindle so the taper turns as if to grind a machine center point? The person, Tom is suggesting that his Studer only has drive-dog to spin the Part as it (the part or a mandrill) is between centers.
Can you explain the headstock locks and such that he may be missing?

Re: Perhaps his headstock's turning ability is simply locked up from age or something...?

 

[ballen]

Buck, I'm going to call it the "workhead" rather than "headstock" because I think that's the correct term.

Yes, on my machine, the workhead spindle can be rotated by a variable speed DC motor with a speed range from about 30-600rpm. You can see it turning in this video:

.
(More precisely, the workhead spindle rotates. Around it is a builtin faceplate rotated by the motor. By attaching two small driver dogs to that faceplate, you can drive the spindle, which has slots that engage the driver dogs.

For cases where you want to mount a part between centers, the workhead spindle can also be locked. The way this is done is via a rotating ring on the far left of the workhead, which increases or decreases the gap in the (journal) bearing of the workhead spindle. Decreasing the gap to zero by pulling the lever towards the operator locks the spindle.

There is also a lock on top of the workhead, which locks the spindle via an internal rotating disk attached to the spindle. The disk has 12 equally spaced slots around its periphery, which are engaged with a locking pin. This is useful when using puller nuts to release MT5 tooling from the workhead spindle taper.

Both locking levers are visible between 10 and 11 seconds into the video above. The first has a black ball on the end, the second is directly on top of the rhs of the casting.

Cheers,
Bruce