Small M3 Running Centre

[SBWHART]

Her's a little tool for you to asymalate

My machine has a M3 morse taper in the tail stock, the running centres you get for this size all seem to be big brutes far too big for the size of work I do, and it not always easy to get in, with a nice robust set up.

So these are the bits I picked up from the Harrogate show: from the Arc Euro trade stand

The arbour was set up in the head stock held nice a secure with a draw bar, faced off and turned down to match the centre:- it was made of some quite tuff stuff.

Then it was centre drilled and with a couple of pilot drills opened out to 9mm by 25mm deep.

Then with a nice little boring bar bored out to 10mm for a nice fit on the centre

Then it was secured with good old high strength loctite:- her it is with its big brother

And how it will look in use

Job done in about 2 hours but it will be a big help in the future

:nrocks:

Stew

 

[SBWHART]

Hi Chaps thought I'd post this showing the running centre in use

This is the Job the Reversing Shaft for my Loco Build

You can see from the drawing that its a bit on the spindly side, with these sort of components its always worth it to try and understand the function of each feature, the two 1/8 dia at each end of the thread have to be concentric with the thread as these are bearings that keep things lined up the Square and the 9ba thread keep the handle on the shaft so its not so important thet they are concentric, in other word they can be turned as a second op, also with this typ of component the operation sequence is important.

So first job is put a small centre in the end of the bar, and then supporting it running centre : turn up the 3/16 dia by 2" length (don't forget to allow for the removale of the centre in the length.) Tip you need a good sharp tool for this type of work HSS is ideal.

Then turn down the 1/8" dia for the longer length (where the square is to go)

Cut the left hand thread with the die

Turn the 1/8" dia at the other end and part off

Then make a 1/8 brass split bush.

Then griping by the split bush turn it down to 3mm for the square (I went away from drawing for this bit)

Then turn down for 8BA and run the die down it (no pic)

To file the square I used the bush to grip in the vice to get one flat, then with this flat up against one edge of the vice it alowed me to file the other sides square (hand eye cordination) I left a bit of meat on the square to alow a bit of fudge factor to fit to the handle when I make it

I made two in case I had a scrapper.

Thats it job done

I do like jobs like that

Have fun

Stew

 

[SignalFailure]

I like that adaptation Stew :bow: as you say the usual live centres are massive beasts. I ground down a couple of dead centres (to less than half - sort of angled backwards) to give better access.