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View Full Version : Cheap Live centers what's your tought?



gstprecision
12-05-2014, 08:10 AM
I've had 2 different live centers in the past few years. Both were chinese made, 1 was a regular $35 and the other was the HD version about $70.

I experienced bad surface finish when machining some 6" long x 0.75" diam aluminum and Steel bars. I was blaming the lathe for lack of rigidity, I was using a Craftex B2227 10x18. One day I was trying to adress the problem so I rigged a couple dial indicator at different spot on my setup and to my big surprise the flex was not from the machine but coming from the tail stock.

I investigated the tailstock and everything seemed fine, no noticeable movement while pushing moderately on it with the cross slide. I then mounted the live centers to find out the center itself had quite a bit of play, approx 0.005" to 0.010" with moderate pushing.

I know the quality of the bearings is not the greatest in thoses centers but was not expecting that much.

Anybody experienced the same? Any good cheap brand suggestions?

Thanks
GST

Doozer
12-05-2014, 08:19 AM
Pay more money and get a better product. A good live center starts at $200.

-D

gstprecision
12-05-2014, 08:45 AM
I knew that was gonna be the first answer.....LOL

Anybody else????

Doozer
12-05-2014, 09:31 AM
What do you expect??? If I had a live center with .005" runout, I would pitch it
in the trash bin an a New York second. A live center is only useful with .001" or
less, even for non-critical things. Something so far out is not worth fooling with.
Are you just posting to get a feel for what others deem an appropriate useable
tolerance?

-D

Old Hat
12-05-2014, 10:44 AM
Learn to use dead centers in the tail-stock.
You can probably even find a carbide center on Ebay for less than a ball-bearing center.

http://www.ebay.com/itm/NEW-MT3-QUALITY-CARBIDE-DEAD-CENTER-MORSE-TAPER-3-LATHE-CENTER-/230840507117?pt=BI_Tool_Work_Holding&hash=item35bf2a9aed

extreme dead center,,,, still afordable.
http://www.ebay.com/itm/NEW-4MT-OVER-SIZED-CARBIDE-DEAD-CENTER-MORSE-TAPER-4-LATHE-CENTER-/230929863932?pt=BI_Tool_Work_Holding&hash=item35c47e14fc
http://i.ebayimg.com/00/s/MTI0OVgxNjAw/$(KGrHqZHJDYFCD!HlJpZBQjBbnZsVg~~60_57.JPG

duckman
12-05-2014, 11:05 AM
Yeah Oldhat that's the way I learned but that was in the old white lead days, now you have to buy that expensive center lube, but I do have a very good live center for my SB9.

KJ1I
12-05-2014, 11:07 AM
Any good cheap brand suggestions?

I, too, figured a reply like Doozer's would be come first. But both comments dodge the OP's question. So I went into the shop and measured the runout on the live center I use on my woodturning lathe. It cost less than $100 and came with 5 interchangeable tips. It's run out measured 0.0015. So if it can be done for a wood lathe at a reasonable price, why not for a metal lathe? Or are the lateral forces so much greater on a metal lathe it just can't be done?

So to paraphrase the OP's question -- Are there any recommendations for a good inexpensive live center?

Old Hat
12-05-2014, 11:09 AM
So to paraphrase the OP's question -- Are there any recommendations for a good inexpensive live center?

a good inexpensive live center = oxymoron.
ie a contradiction of terms.

Toolguy
12-05-2014, 11:21 AM
Take the junk one apart and replace all the bearings with good quality ones. Then you will have a good live center for a junk price. The bearings are fairly cheap, comparatively.

gstprecision
12-05-2014, 11:35 AM
I do know what a good quality live center is. I have a good one and use it all the time, but sometime the size does not fit so I use the cheap ones. I just wanted to know if anybody had some less expensive brands they used and liked. I could keep them in mind on my next purchase.

I am a bit upset by the animosity in some reply. I experienced the same kind of answer on another machinist forum before, but it is the first time here. I recheck the website name to make sure I did not inadvertantly posted in the wrong forum, but it is HOMESHOPMACHINIST allright.

GST

RichR
12-05-2014, 11:58 AM
Assuming the play is in the actual bearing and not in how the bearing is fitted, I'd second Toolguys suggestion.

Old Hat
12-05-2014, 11:59 AM
a "Sencitivity" machinist's forum?

cameron
12-05-2014, 01:24 PM
I am a bit upset by the animosity in some reply. I experienced the same kind of answer on another machinist forum before, but it is the first time here. I recheck the website name to make sure I did not inadvertantly posted in the wrong forum, but it is HOMESHOPMACHINIST allright.

GST\

What animosity?

It's not the HOMESHOPMACHINIST , it's the homeshopMACHINIST. Have you ever come across a MACHINIST who wasn't opinionated?

janvanruth
12-05-2014, 02:19 PM
I am a bit upset by the animosity in some reply. I experienced the same kind of answer on another machinist forum before, but it is the first time here. I recheck the website name to make sure I did not inadvertantly posted in the wrong forum, but it is HOMESHOPMACHINIST allright.

GST

although overthere nobody is being called a clumsy basterd ;)

RussZHC
12-05-2014, 03:13 PM
I've been happy with my Skoda, its MT 2 so not that large but apparently parts are available for rebuild.
Skoda via SOWA come up for sale nearly monthly, not huge price break but some.

Not a Riten or Royal but not the same $$$ either.
Both come up on EBay at considerably lesser prices but prices are also all over the map since both makers have a huge selection, long points or triple bearings for example.

Alistair Hosie
12-05-2014, 03:24 PM
Am I reading this correctly CHINESE live centres and you expect BEARINGS too .hee hee hee hoh hoh hoh thats funny.Usually they have little beetles running around inside a small wire squirrel cage. Alistair

raceneer
12-05-2014, 03:55 PM
I've had good success with middle tear chinese live centers. If you look closely when you fiddle with them you'll see they seat once force is applied. Runout of .001 in the old imperial scale is obtainable. From memory mine was ~.015mm. About $40 from aliexpress.

Alistair Hosie
12-05-2014, 04:18 PM
I too can reommend Skoda live centres not the cars.They are really very good. I think the cheaper ones to be serious, are actually better used with a woodturning lathe.Thats what I do or used to do now over the years I have treated myself to better made ones for both wood and metal .Alistair

Doozer
12-05-2014, 04:31 PM
Another PLUS for Skoda (Polish made) for a decent center at a good price.
I got a 2MT Skoda at Enco on sale for ~$40 a few years ago.
Runout is about .0005" TIR.

-Doozer

gstprecision
12-05-2014, 05:05 PM
I'll check with my local tool supplies, they are a Sowa dealer.

Doozer, you're right, never met a unopinionated machinist.....lol

GST

GT1
12-05-2014, 05:42 PM
I have used the Enco import version for the past 10 years ( 3MT currently listed for $48). I just checked the runout and it was well within 0.0005". With that said, it probably does not have more than 10 hours of run time on it. I would have no problem recommending it for a home shop. I also have Enco's Bullnose live center and it is a piece of junk. I plan on taking it apart someday and maybe replacing the bearings, but I'm not to hopeful.

Okapi
12-05-2014, 07:15 PM
If you want the rolls of live centers, try to find a GEPY on the second hand market, they are smaller than normal then more usable on small diameters and make for the clockmakers indutry at first.

macona
12-05-2014, 07:46 PM
I have one of the skodas as well. Very nice center.

oldtiffie
12-05-2014, 07:59 PM
Are those that have/had a largish TIR - are you sure that the shank/MT of the centre was a very good fit in the tail-stock quill and just as good a fit of the quill in the tail-stock.

I see no mention of using the steadies - "fixed" (to the lathe bed) and "travelling" (fixed to the carriage".

Why is that? - as both are very handy when used and used correctly.

macona
12-05-2014, 08:37 PM
You really shouldn't need a steady on something 6" long and .75" in diameter.

gstprecision
12-05-2014, 08:55 PM
I agree with follower rest use to eliminate some of the flex.

Never really tought about poor fitting MT shank, good point.

GST

oldtiffie
12-05-2014, 09:50 PM
If (when) my "live" centre was running out (too large a Total Indicated Run-out - TIR) I'd fit it into a good MT4>MT2 sleeve and put the sleeve into my head-stock taper, fit my tool post grinder, set it to 30/60 degrees (depending on how your top slide scale is calibrated) and then start the lathe and TPG and grind the live centre as required.

Take it easy and there will be sufficient "drag" on the centre to keep it passing the live centre past the grinding wheel.

It would be a good idea tore-set the "loading" on the centre bearings too and to also check the condition of the centre MT shank.

oldtiffie
12-05-2014, 09:52 PM
You really shouldn't need a steady on something 6" long and .75" in diameter.

Perhaps so - perhaps no.

Its always a handy option if/when you might need it.

boslab
12-06-2014, 12:25 AM
I got really lucky and found a skoda at a car boot sale, little rust but cleaned off nicely, it's a bulky beast but it doesn't have roller bearings like the Chinese ones, they are taper rollers, as it goes under pressure the thing tightens up, I found a bit of play when it was unloaded but when a test bar was put between centres and the tailstock tightened up I had trouble picking up 0.0001 when side loading the bar with the toolpost, definitely something worth getting, and you can replace the bearing with a new one cheaply
Mark

Old Hat
12-06-2014, 02:15 AM
I've been happy with my Skoda, its MT 2 so not that large but apparently parts are available for rebuild.
Skoda via SOWA come up for sale nearly monthly, not huge price break but some.

Not a Riten or Royal but not the same $$$ either.
Both come up on EBay at considerably lesser prices but prices are also all over the map since both makers have a huge selection, long points or triple bearings for example.

Skoda anything is GRAND stuff. Checkxslsllavackian... enginuity!
A Skoda Bar may be the most powerfull and well built there ever was!
http://www.resale.de/images/3460227_a_SKODA_WDB_160.JPG
Great pic of cutting a rotor for a generator.
http://www.pateltech.com/wp-content/uploads/2014/10/ram-type-floor-boring-machine-7000-mm-skoda-wd160-b243-1413784841.jpg

boslab
12-06-2014, 04:52 AM
I still believe they were making steam engines up to at least the 70s, I think, though not definite that they do?, for china in particular, or at least spare parts
Mark

bob ward
12-06-2014, 06:15 AM
gstprecision I bought an MT3 one of these earlier this year, TIR is .0008". Cheap and cheerful.

http://www.ctctools.biz/servlet/the-690/MORSE-TAPER-LIVE-CENTER/Detail

Old Hat
12-06-2014, 08:51 AM
I still believe they were making steam engines up to at least the 70s, I think, though not definite that they do?, for china in particular, or at least spare parts
Mark

Yes they were!
Incidently in the machinery above, the lead-screws don't turn, and look at how much column contact
the head-stack has, nearly twice what the rest have!

At the base of the column are kicking scews, built in to align the column.
Skoda = Bar~Zilla!:cool:

kitno455
12-06-2014, 10:12 AM
Have you determined if you can increase the pre-load in the bearings? Might be a simple adjustment.

allan

DR
12-06-2014, 12:02 PM
Take the junk one apart and replace all the bearings with good quality ones. Then you will have a good live center for a junk price. The bearings are fairly cheap, comparatively.

How can you be sure the point is ground concentric with the bearings? I would guess the cheapness of low cost centers is in the machining/finish grinding. Of course, cheap bearings are an issue too, but I bet a lesser issue.

Kind of like putting grade 9 bearings in a HF lathe.

RichR
12-06-2014, 12:10 PM
How can you be sure the point is ground concentric with the bearings? I would guess the cheapness of low cost centers is in the machining/finish grinding. Of course, cheap bearings are an issue too, but I bet a lesser issue.

Kind of like putting grade 9 bearings in a HF lathe.

The OP stated:

I investigated the tailstock and everything seemed fine, no noticeable movement while pushing moderately on it with the cross slide. I then mounted the live centers to find out the center itself had quite a bit of play, approx 0.005" to 0.010" with moderate pushing.
I think that would suggest suspect bearings or how they were fitted and not a poorly ground point. Or maybe the shank not seating properly
in the tailstock.

Alistair Hosie
12-06-2014, 03:29 PM
Wow the Czechoslovakians know quite a bit about painting their machinery. I particularly like the fact they are,quite correctly as they should be all green. Alistair is not alone guys LOL Alistair

gstprecision
12-06-2014, 08:52 PM
Not sure what kinda bearing they were, and if there was any adjustment.

I got rid of these cheap live centre when I sold my baby lathe, the reason of the post was that I wanted to know if there was any good cheap replacement out there. I'll be definately looking for Skodas.

GST