Ruined live centers

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rtparso

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I seem to be ruining live centers. The point works into the mandrel. No damage to the mandrel but there is a grove worn into the live center 1/8†pack from the tip. I thought maybe I had over tightened the live center so on the last live center I left it much looser. I just tightened it to the point I felt a slight drag. BTW I tend to turn with the lathe speed turned all the way up.
 
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What types of centers are you using? I ruined my first one that came with the lathe, and bought a nice one from Harbor Freight. No wear on it! I might have a pic of it in my album if you want to look. The cost of the H.B. center was less than $20.00
 
I've not heard of doing that before, but I suppose it could'nt hurt. It really should'nt be necessary to lube the contact point, as the center itself should spin freely on it's bearings.
 
I can't remember who told me that before, but a little moly would prevent any possible drag...especially if there is a small amount of resistance in the bearings.

If I remember right, it had to do with rapid starts and stops.
 
The truth is ... (and the pen suppliers don't tell you ...!)

The mandrels require a live center that is designed for METAL or machining work. The usual woodworking live center does not work, and gets worn very quickly.

The metal working live center is a 60° included angle, like this one:

http://www.littlemachineshop.com/products/product_view.php?ProductID=1189

They are sold by LittleMachineShop above, and by Grizzly, HF, and some of the woodworking supply stores.

This is the only kind that fits the mandrel. The angle in the woodworking live center is too wide, and will be cut into by the edge of the mandrel hole.
 
Ron,
I'm baffled. I've turned over 200 pens and other stuff with that Live center, well in MT 2. Not MT 1. Size of MT shouldn't matter. The nose piece is hardened steel. To get scoring, you would really have to crank on the pressure... All your pens would be Oval... Only other thought would be bad steel...

Another thought:
Have you "dressed" the end of the mandrel? May be a "spur" left from drilling the dimple... A little filing should correct that.

Let us know what Grizzly has to say...[:)]
 
Originally posted by rtparso
<br />I seem to be ruining live centers. The point works into the mandrel. No damage to the mandrel but there is a grove worn into the live center 1/8†pack from the tip. I thought maybe I had over tightened the live center so on the last live center I left it much looser. I just tightened it to the point I felt a slight drag. BTW I tend to turn with the lathe speed turned all the way up.
Click to expand...

Hello. I had the same issue with my stock jet live center. You need to purchase any live center that has a 60 degree point. That will solve the issue.

James
 
I had this problem, this is what I learned. there are two types of live centers. those for turning wood, and those for turning metal. although we turn wood we have a metal mandrel in contact with the center. answer to the problem. you need a metal lathe live center. luckely they are not that hard to find.HF, Enco (where I got mine), the Little Machine shop, and others have them. I think mine cost about $30.00, that was after destroying two $20.00 craftsman centers.
 
The center of my live center that came with my Grizzly lathe wore out. Even though it is removable, Grizzly does not sell replacements. I had to buy a whole new unit. And now I see that it is wearing out also. I believe I'll go with the suggestion to buy a hardened machine-tool type for mandrel use.
 
A little lub will help, but the soultion is like others have mentioned a live center for metal lathe with a 60 degree tip. The lub will slow the wear down but not fit the problem. I run metal live centers on my mini lathes and wood live centers on large wood lathes.
 
I have had the same problem with live centers. I am on my second 60 degree live center from CS and it is starting to wear like the first one. In my case the problem is the result of tight bearings (On the first the mandrel would bow if the center was tight enough to turn and was very badly worn after only 6 pens, CS replaced it. The second one is better, but is beginning to wear also.). The other problem is the metal the center is made of is much softer than the mandrel, and it appears that when the point of the center was turned it got hot as the metal is very porous (the porosity shows after the point starts to wear).

I'll pprobably try the metal lathe center next time I buy.
 
If you have ruined the point in your WOOD working live center from Jet, Woodcraft sells them for a couple bucks. They are not in the catalog, but the stores carry them.
 
Just had this happen on mine, too. I'm looking at replacing it with this:
http://www.woodcraft.com/family.aspx?familyid=3727

Has anyone tried it? The other option for me is:
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=38573
But with this one I'll have to wait for HF to ship it, and I'll have to pay shipping (the local HF store doesn't have it, but the local Woodcraft has the other one). The one from Woodcraft has replaceable centers, which sounds appealing for some of the other stuff I want to turn, too. My only concern is that there won't be a 60 degree center in it.

Any feedback?
 
I have looked at similar live centers but that is the least expensive that I have seen. The only drawback is that the inserts are matched to the head. What I am thinking is to take one of my live centers drill it to something like ¼†then inserting a short piece of ¼†drill rod and grinding a 60 º point on the piece of drill rod. What do ya’ll think?
 
Interesting idea Ron! Let us know how it turns out, please! I went to Woodcraft earlier today and got the live center with the removable tips from them. They had the #2MT version on sale for 20% off. They also had a few other live centers from which to choose, some as low as $12, but they had the standard woodworking tip, not the 60deg tip. I hope to play with the new center this weekend, and I'll let you know whether/how it works.
 
OMG... you went to Woodcraft without me???? [:0] [:0] ...LOL

I haven't noticed any wear on mine, but I haven't really looked at it either. I will be checking that however. I like the Woodcraft center, options are nice!

(We haven't seen any pictures of your new resin pens yet!! [;)] )
 
Jim, I bought the same live center set. I use it only when the regular live centers will not do. Main reason is that I don't think I will be able to buy spare points for it. On the other hand, I think I could make them myself if I had to.

On this whole question of live centers for pen mandrels, I would like to add that a center with a 60• angle is not the only possible way to go.

A cup center will work ok too. I made one by drilling a shallow hole in the head of a 1/4" bolt with a 'D' drill bit. To get it centered correctly it has to be drilled in the lathe. If I did it again I would use nylon instead.
 
Interesting idea; thanks Fred! I think there was a cup-like center in that set; maybe I'll give that a try.

Michael, I went at lunch time. I had to run to the Patent Office to hand-deliver something for a client, and since I was down that way, well, I felt I HAD to stop in Woodcraft! :) Picked up a few other goodies, too. As for the resin pens, the black/gray ones weren't dark enough; you could see the brass tube through them. The skin pens I tried all had "issues" (the brass tubes all came unglued (tried a new kind of glue that OBVIOUSLY didn't work), the resin broke off one skin completely, another one cracked once I had it close to the final size, and on another one I was trimming then end and the tube slid, so I wound up trimming the skin too short). As for the pink ones, the CA I tried on those tubes didn't work, and I need to re-glue. If I remember, I'll glue those tonight.
 
You are most welcome, Jim.

Talking about drills, one of the most useful sizes for me is the size D. It is .246". Just right for the cup center, and just right as a tool to clean inside a 7 mm tube.
 
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