Resurfacing 60 degree Centers

jroma1

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I would like to resurface the 60 degree centers on my lathe,the question is how? I've seen demos' on YouTube where a toolpost grinder is used and is this the only way to achieve this operation. Now even on ebay,toolposr grinders aren't cheap. It is my understanding that these centers are hardened tool steel. Is there another way to cut this steel?

Another thought and from what I'm told there are those that have made there own TP grinders,anybody got any comments or suggestions.
Any and all response will be greatly appreciated

John
 
G'day John.
Are these "dead" (tailstock centres) that you are talking about? If so they are usually hardened. If you don't have a tool post grinder, it wouldn't be hard to make up some sort of bracket to hold a die grinder with a stone in it, (by that I mean not a rotary burr) in the tool post. Actually a bracket to hold whatever sort of hand held grinder you have would work. You could use a dremel type , even a small angle grinder with a flap type wheel would work.
Just make sure ther are no dings, burrs etc in/on the tapers in the spindle and sleeves etc.

regards
bollie7
 
As Bollie7 mentioned, a TPG is the best way to work on hard metal. I've never tried a "dremel-tool" type of TPG and don't know how well they work in this scenario -I'd appreciate anyone's comments from real-life experiences. Anyhow, there are other complications here such as how do you plan to chuck-up the morse taper? You'll need a holding fixture of some sort because a spinning center with sideways pressure on it could come flying out. -It's not good to have pointy metal things flying around the shop. This leads to the next issue: Accuracy. The tip on a center needs to be fairly precise and by the time you make fixtures etc, you could end-up with a wobbly tip due to alignment error stack-up.

I'm not trying to discourage you but rather pointing out that in this case, the money for a new center might be a wise investment. If it's a live center, some have replaceable tips. Dead centers are pretty cheap to replace... Also, dead centers can be purchased with carbide tips and they last much longer than tool steel versions.


Ray
 
As Bollie7 mentioned, a TPG is the best way to work on hard metal. I've never tried a "dremel-tool" type of TPG and don't know how well they work in this scenario -I'd appreciate anyone's comments from real-life experiences. Anyhow, there are other complications here such as how do you plan to chuck-up the morse taper? You'll need a holding fixture of some sort because a spinning center with sideways pressure on it could come flying out. -It's not good to have pointy metal things flying around the shop. This leads to the next issue: Accuracy. The tip on a center needs to be fairly precise and by the time you make fixtures etc, you could end-up with a wobbly tip due to alignment error stack-up.

I'm not trying to discourage you but rather pointing out that in this case, the money for a new center might be a wise investment. If it's a live center, some have replaceable tips. Dead centers are pretty cheap to replace... Also, dead centers can be purchased with carbide tips and they last much longer than tool steel versions.


Ray

Some good tips. Also use high speed axle grease to lubricate the center and work-piece. Good luck
 
I used to re cut HSS or carbon steel 60º centers by turning them with a carbide lathe tool. Run the lathe fast. I'm not sure how well this would work with a mini lathe.
 
Little Machine Shop sells a very inexpensive tool post grinder that will adapt to most smaller lathes up to 13/14" swing lathe. it uses a 3" wheel which they sell, too. I bought one thinking of using it for my lathe bed regrinding project and decided it was not big enough for the challenge. Wound up using one of my Rockwell 1-1/2HP router motors, which work like a charm. That maybe another option to try if you have one handy that's not being using for woodworking.
 
I have some T&C grinders I could do them on but the shipping to and from may be more than a new center is worth. Anyhow, the offer is out there.
 
Generally speaking, there is a taper sleeve for the headstock taper that reduces it to the same taper as the tailstock taper; you insert the hard tailstock center in it and regrind the point. The center for the headstock is made soft, and generally has a groove turned near it's point to indicate that it is soft and is recut if not true with a cutting tool. I make a witness mark on the end of the spindle, the taper sleeve, and the soft center so that it may be be returned in the same position so that recutting is seldom necessary for concentricity.
 
I would like to thank all those members that responded to my post "Resurfacing 60 Degree Centers". My main reason for wanting to grind my own centers is because I want to make my own live center. I made one live center that didn't last too long,right after completion the runout was somewhere between .002" to .003",after using it several times the runout climbed to .007".

In my opinion,the reason for this failure was that the bearing used was too light plus the center itself,although made out of drill rod was not hardened.

The method I used to make this part was I purchased a MT2 shank with a blank end I then with the help of a MT3-2 adapter machined a referance diameter then a threaded diameter. I then inserted a piece of 1.3125"stock into a three jaw chuck and bored a matching referance diameter drilled and tapped a thread to match the shank. This is the start of the main housing,assembling the two parts together I used the same MT3 to MT2 adapter. After removing the 3 jaw chuck I inserted the entire assembly in the head stock,bored a hole for the bearing for a press fit. Note;the center itself was made before any of the above using a four jaw chuck. A cover was made to close off the end and was drilled and tapped on the circumferance to secure it in place. The screw holes went all the way thru to pin the center from turning. Reason: So that I could recut the 60 degree end,the screw was removed and replaced with a shorter one.

I intend to take the same approach except with a larger and longer bearing,heat treating the center is another problem any suggestions comments greatly appreciated.

As far as a tool post grinder is concerned I tried using a Dremel tool with very poor results,I have a HF 9 x 20 lathe too small for a right angle grinder

Thanks
John
 
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