crrmeyer
Stainless
- Joined
- Nov 10, 2006
- Location
- Southern California
I am looking for a MT2 relieved dead center as shown in the photo. Please PM me if you have one forsale.
Thanks
Thanks
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WTB: Relieved dead center
- Thread starter crrmeyer
- Start date
- Replies 21
- Views 3,129
trevj
Titanium
- Joined
- May 17, 2005
- Location
- Interior British Columbia
crrmeyer
Stainless
- Joined
- Nov 10, 2006
- Location
- Southern California
Lucky7 - thanks for the better search term. They are pretty common it turns out.
Trevj - So before spending money on one I figure I might have a generic MT2 dead center around to modify. Around 2006 there was a seller on PM who ran into a large stock of ~1952 vintage NOS live and dead centers from a Huron Machine & Tool Company. So I picked up an assortment of them, wrapped in the stickiest anti-rust wax/lanolin paper I have ever seen. Turns out, in that order there was a never unwrapped MT2 half dead center. So I have a almost 70 year old dead center that looks like new for the tailstock!
Trevj - So before spending money on one I figure I might have a generic MT2 dead center around to modify. Around 2006 there was a seller on PM who ran into a large stock of ~1952 vintage NOS live and dead centers from a Huron Machine & Tool Company. So I picked up an assortment of them, wrapped in the stickiest anti-rust wax/lanolin paper I have ever seen. Turns out, in that order there was a never unwrapped MT2 half dead center. So I have a almost 70 year old dead center that looks like new for the tailstock!
plastikdreams
Diamond
- Joined
- May 31, 2011
- Location
- upstate nj
I don't think I've ever seen a dead center used in a tail stock....
crrmeyer
Stainless
- Joined
- Nov 10, 2006
- Location
- Southern California
It is for use with a Bison rotary table on a milling machine. I guess you could use a live center, but that does not work very well if you need relief clearance on the center, since the center rotates. The speeds are almost non-existent, so a little lube on the dead center should be fine.
plastikdreams
Diamond
- Joined
- May 31, 2011
- Location
- upstate nj
Ah this makes sense.
Mark Rand
Diamond
- Joined
- Jul 9, 2007
- Location
- UK Rugby Warwickshire
Where else would you use it? If it were in the headstock it would be a live centre.
A 'full' dead centre or a rotating centre in the tailstock may limit access to the part where a half dead centre doesn't.
thermite
Diamond
- Joined
- Sep 21, 2011
Use it up while you still can!
Based on the condition of my own half-dead center in the 76th year each time I hit the loo to relieve the poor thing, a 70 yr old one only has about five years of life left in it before it morphs into a rubber-band!
plastikdreams
Diamond
- Joined
- May 31, 2011
- Location
- upstate nj
Are you high? Dead center in the chuck with a dog on the part. Live center in the tail stock. The part rotates the same as the chuck and the center at the same time...
But really, you are high right?
morsetaper2
Diamond
- Joined
- Jul 2, 2002
- Location
- Gaithersburg, MD USA
I got in on that same buy way back then. Have used that relieved MT2 center a couple times myself. And yes, I don't think water could penetrate that preservative paper unless it was totally submerged for an extended period.
Milland
Diamond
- Joined
- Jul 6, 2006
- Location
- Hillsboro, New Hampshire
Are you high? Dead center in the chuck with a dog on the part. Live center in the tail stock. The part rotates the same as the chuck and the center at the same time...
But really, you are high right?
Oh, good, I get to play "grumpy old man" again...
Listen up, young'n! Way back in the olden days, before your highfalutin "rolling element bearings", we use to have tapered holes in ends of shafts, and into them tapered holes we'd shove tapered centers - Dead Centers, 'cause we din't have no live ones!
OK, more to the point (ha, is joke) dead centers are used all the time in tail stocks, usually when the best possible precision is needed in a low-speed operation, like grinding a shaft "perfectly" round. Some high-pressure lube is needed on the center point, and ideally at least one of the two cones (male or female) is lapped true to give best accuracy.
I believe you don't want both lapped because you want some geometric asperity to contain lube pockets (much like scraping rather than two ground surface working as sliding elements).
The issue with a live center is that you're subject to the inaccuracies of the bearings, while a properly prepared dead center will give roundness as close to "perfect" as you're likely to get in a shop setting.
Milland
Diamond
- Joined
- Jul 6, 2006
- Location
- Hillsboro, New Hampshire
Along this line, many cylindrical grinders have a true dead center in the headstock also, with a coaxial drive creating the rotation of the workpiece. Again, the best roundness in normal machining processes will come from well-prepped dead centers rather than rolling bearing center, because you're eliminating the inevitable geometric errors of rolling elements.
Now, you have to do it right, of course - the right (low, but positive) preload, the right lube to prevent seizing, keeping the shaft from overheating, etc. It's easy to screw up if you don't understand the process, but any grind shop that does cylinders will use the method when needed.
Now, you have to do it right, of course - the right (low, but positive) preload, the right lube to prevent seizing, keeping the shaft from overheating, etc. It's easy to screw up if you don't understand the process, but any grind shop that does cylinders will use the method when needed.
eKretz
Diamond; Mod Squad
- Joined
- Mar 27, 2005
- Location
- Northwest Indiana, USA
Yep, dead center use is very common in OD grinders. Usually center pressure is preset - one doesn't have to worry about getting the center pressure right because it's spring loaded. The spring sets the pressure, then you lock the spindle.
Dead centers repeat WAY better than rolling bearing centers in most cases. If you take out a part from a live center and put it back in and check runout it will often not be running at perfect zero TIR anymore. With dead centers it is exactly the same at zero TIR even with repeated removals and resets.
Dead centers repeat WAY better than rolling bearing centers in most cases. If you take out a part from a live center and put it back in and check runout it will often not be running at perfect zero TIR anymore. With dead centers it is exactly the same at zero TIR even with repeated removals and resets.
I use dead centers in my tail stock exclusively. My "American" has 7 sets of ball bearings in the tail stock. I often turn the dead centers into the profile I need before putting it into the tailstock. Just use ceramic inserts and run your speed about 400 to 600 rpm. I have to clean up a center every once in a while, when running 900 rpm and pushing my cutter hard bouncing coils of steel off the wall sometimes the center gets a small groove in it. Just pop it into a taper holder, chuck it up, and voila!
thermite
Diamond
- Joined
- Sep 21, 2011
Standard practice was to run with a massive 5 MT LC until close to final passes. THEN stop. clean up, switch to a DC and basic white lead carbonate for final to specs at lower stress.
Cimcool center-saver AKA "pink slime" nowadays, far, far, better than lead.
Get a lot of mileage out of an ignorant DC that way,"all manual" world.
Milland
Diamond
- Joined
- Jul 6, 2006
- Location
- Hillsboro, New Hampshire
Really? Never used the Cimcool, does it just reduce friction, or resists wash-out better, or ?
thermite
Diamond
- Joined
- Sep 21, 2011
"All of the above" in-use. Slicker than shit out of a teflon-eatin' barn Owl.
And then.. it don't f**k-up yer fancy French-lace shop-smock as bad as Moly. leads, nor graphites are wont to so. Even launders right out.
Try it. Small tube will last yah a while, less yer turning mill rolls or the like. The (corporate remains of) "The Mill" as make it. Or HAVE it made. But "the usual suspects" carry it. ISTR about five bucks a tube a few year back, my last order?
DON'T like it? Run it up yer ass as a sub for polydent next time you go on a "TDS" driven "orange-man EVIL!" rant, and amuse the f**k outta the community when yer dentures crack the sound barrier on "commutator wedging" ejection off the heat-rise
..and get wrote-up as yet-another unexplained alien UFO as they fly past Area 51!!
I did say "pink slime" was "slippy?"
Milland
Diamond
- Joined
- Jul 6, 2006
- Location
- Hillsboro, New Hampshire
DON'T like it? Run it up yer ass as a sub for polydent next time you go on a "TDS" driven "orange-man EVIL!" rant, and amuse the f**k outta the community when yer dentures crack the sound barrier on "commutator wedging" ejection off the heat-rise
..and get wrote-up as yet-another unexplained alien UFO as they fly past Area 51!!
I did say "pink slime" was "slippy?"
Yeah, thanks for that. I guess you're cool with Putin's Pet OK'ing the bounties on US soldiers. How your mind can bit-flip so readily is worthy of a pathology researcher.
thermite
Diamond
- Joined
- Sep 21, 2011
LOL!
Yah think? Nah. Yah do NOT "think", do yah?
Would never cross yer tiny mind you have been operating at the "subject" not "observer" end of the microscope the whole while?
Nooo. Yah COULD not could yah?
Occupational hazard with lab-rats.
Go figure they don't seem to get promoted to better jobs all that often.
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