Tailstock pressure

[earlgo]

Mr. Hasler: I recently purchased a #2MT live center from SHAR #202-3436 and it was not expensive, currently listed at $17.50. It is all anyone could want for a hobby lathe. Unfortunately it cost nearly $10 to ship at a flat rate, but still a good deal at less than $30.
Just an opinion.
--earlgo

[Rich_Carlstedt]

Tailstock pressure is a function of the work being done and the tailstock center tool , (dead or live ie)

For turning a 1" shaft as you mentioned, bring up the center and just snug it against the turning work. If you start turning and the work moves away from you or chatters, you are too loose. Adjusting the tailstock during cutting is a normal part of lathe work, especially long pieces. Long work heats up and expands outward , so a good habit to have is to touch the center and see what temperature it has. As it warms, release the pressure, or just unclamp the tailstock and then immediately reclamp. Do not do this during a cut or it will most likely groove the work piece. If your center is warmer than the work piece, you most likely are too tight. If it is too hot to touch ( 140F + ) you have a major issue. If Your workpiece is forced back into the chuck , you have a major issue. Remember the function of the tailstock center is ONLY to allow radial cutting forces to be supported/opposed away from the chuck

There is one application that does require high pressure from the tailstock and that is called " Pressure Plating " . Usually this is when you have a flat work piece placed up against a face plate and use the tailstock to hold it in place to prevent ANY movement . Here, you wants lots of pressure

Lastly , the pressure is a function of the type of center.
A dead center with oil or grease can only take so much force before friction causes problems ( like welding !)
A dead center with white lead or Moly lube can take much greater forces than oil/grease
A Live Center with a single ball is better at force allowance
A Live Center with ball bearing (s) is even better at force allowance ( 10x !)
A Live Center with Timken Rollers or Needles , can take a lot of force !( 100x !)

Rich

[tomjaksa]

I also wonder about centre pressure.
I am just starting in machining and would like to learn the right way first time and turn it into a habit,
My centre looks like this.

Just looked at the Rohm website.....over $1000 thats 15k in my money.
I think i will put it on the shelf and get a cheapie for everyday work.

[curtis cutter]

Is there a manufacturer and model # on this center Tom?

[tomjaksa]

Yup its a Rohm

[tomjaksa]

just googled the serial number its 503AC MK3
It only costs $843 my apologies........

[John Hasler]

Sell it on Ebay and use the proceeds to buy several good quality live centers, an nice toolpost, and a couple of cases of beer.

[ctwo]

Nobody needs a center like that Rohm, but does that say it redlines at ~1000 pounds? Makes me think that everybody instead needs this tailstock pressure to show up on the DRO

[tomjaksa]

According to Rohm this centre is designed to do Centre Plating as well as rich said above in his post great post.
Way too Fancy for my needs. Now for that money i would prefer one that makes coffee.

[Harold_V]

According to Rohm this centre is designed to do Centre Plating

I'm at a loss to understand how a center capable of displaying pressure is related to plating, or, for that matter, that a center is required for plating. I must be missing something, eh? Can you help me understand your comment, please?

Harold

[John Hasler]

"Center plating" means using the force of the center to hold a flat part against a faceplate while you turn it. There have been times when I would have used the technique if I had a live center.

[Magicniner]

"Center plating" means using the force of the center to hold a flat part against a faceplate while you turn it.

I suspected it may be a poorly chosen term for that but I've not come across it before and I've been using lathes and and reading technical engineering works for some time.
It doesn't appear to be a common current term either,

- Nick