Refreshing A Dead Center?

[Chipper5783]

This is one of the centers that came with the lathe -- it is specifically meant for the tail-stock ram (the spindle is a different size).
It just has wear and needs to be re-pointed. There was a comment earlier about it not being worth fixing -- I'm pretty sure these are meant to wear and be cleaned up periodically; it is a dead center after all and will be subject to a lot of friction. I would rather have the $5 tool wear than the part I'm trying to turn... Decided to lookup the part on grizzly's site to check whether it was supposed to be hardened or not, and couldn't find it as a replacement part. Did find that most listed are hardened - but I'm still pretty sure the ones that came with the lathe weren't...

My live center is pretty fricking huge, which makes it just about impossible to get a tool anywhere near the tail end of the work piece (even coming at it with a right-handed cutter) without a large cutter stickout... I should probably look for a smaller live center as well now that I'm thinking about it...

The size does not determine the location the center would be used. Usually the lathe manufacturer provides a sleeve for the spindle taper, and the reason is so you can both have a good sized spindle hole and employ reasonably sized spindle tooling for the machine (i.e. you probably don't use much MT4 tooling on a G0602). A 4MT center is pretty big, it may take up additional bed length.

You are correct about simply re-pointing. It is true that new ones are cheap, but repointing is very straight forward.
You raise a good "point" about not wanting to wear the part. When a center wears, it will wear the part. So long as the wear during the job is minor, you can finish that job - then fix the center if need be. If the center wears during the job - well, that is not so good. Obviously you can do things to minimize this wear: lubrication (which you have already "pointed" out), don't let the load get too high (manage thermal growth, keep the tool load down), don't run the speed too high and use a hard center. Most folks likely use soft centers in the tailstock from time to time (if I needed to get in close on a small part, I'd grind out some room and get'er done - then repoint the center).

Griz doesn't have this as a replacement part, yet they supplied it with the lathe (perhaps their price on soft centers is $0.02 cheaper, which helps them keep costs down)? Griz sells lots of stuff, but there is plenty of cool stuff that they don't offer (others do). Most centers sold probably are hardened since tailstock use is likely the more common application and more likely to get damaged. A head stock center should last a long time, and is very easy to repair.

Did you get two centers with your lathe? Was one of them hardened?

If you do much small work in close to the tail stock, consider getting a half center. You can get extended point live centers, which help on getting in close to the tailstock, but that does eat up some bed space. I think you are on the right track to sort out using dead centers. Live centers are great, but folks should not reject using dead centers - they bring a number of benefits (stiff, cheap, short, simple, easy to service, can be very accurate).

 

[Round in circles]

Re Chippers post ( aka David ) above ,
You can also grind away part of a dead centre so that you can work even closer to the centre line axis with the cutting tip , positioning the ground out face towards the cutter .

 

[kizmit99]

The MT2 to MT3 adapter arrived, so I turned and repointed the old center:



Anyway, the center definitely didn't seem to be hardened. HSS seemed to cut it just fine. Although I didn't end up with the greatest finish, I think it'll do...

 

[joshua43214]

You should polish that up. You really want a good polish on a dead center.

 

[chevydyl]

I agree with the polish, I also agree that you MUST indicate the proper taper, just because you set your compound to 30deg or 60 whatever, chances are you are NOT cutting 30deg dead nuts which is what is required for a center, it needs to seat properly into a drilled out center so that cutting forces don't cause a slight change in the diameter of your work, or it can ruin the center in your part and ruin the freshly cut center, it will put a line around where it is actually touching, I would use some bluing to check the mating on a center hole. its possible that your 30deg setting on your compound is actually gonna be 30.5deg, or when you move the compound and then put it back to 30, its 29.5....

 

[The Liberal Arts Garage]

Actually not worth your time to regrind the point,too much metal to remove plus a new one is about $5.00
If the point is hardened,sure does not look like it ,you have to anneal it.
If you really want to save the dead center it is possible to turn or grind the point.Remove the chuck. Install an adaptor,#3 morse taper /#2 morse taper. Assuming the headstock spindle is a #3 MT.Set the compound to 30° and turn a new point.If the point is hardened ,grind it instead. Figure a way to hold a stone in the tool holder and grind away.Vacuum the grinding dust right away.By the way,oil or grease the center often as you use it.
Personally, I would buy a new hardened dead center or a live center with a long slim nose.There are live center sets that may be of interest to you.

mike

Odd little suggestion: Mix a little anti- sieze with a few drops of oil.
Find a tiny plastic pot. Install a flux brush in th lid. Keep it free o swarf. Just a tiny
dab-----BLJHB. ( If your lathe is Really old, there is a tiny cast- in pot at the tail-
stock. This is to hold white lead to lube centers. Little project-- make a combo lid and
dauber to fit.)