Ball or Radius cutter

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MadNick:
Thanks for the support fellas.

I made a fresh start on my more elegant solution and fabricated the following using some 1/2" plate I had knocking around -

As you can see I used a boring bar to cut the recess for the centre gently, gently and plenty of collant gave quite a decent cut and square edge - I was pleased with it anyway.

Having purchased some thrust washers I really wanted to see if I could come up with a slightly different solution to everyone else

The washers fit really nicely into the recess that I bored out -

Onto my question. You see the lump of ali in the second picture well I want to use that to make the turret with - its exactly the same length as per my requirements but needs to be taken down from 75mm diameter to 56mm, wants a step putting into it and a 10mm hole drilling and tapping to locate it to the the base.

How would I do this please as I am unable to turn the diameter down the whole length of the piece whilst its in the chuck.

Nick

adamriley:
Hello Nick, I recognise that lathe...
Is it a Barker?
I have one too, so will be watching this thread with great interest...

Adam.

Divided he ad:
Nick,

In answer to your question (well, my answer anyway) If you are putting the 10mm hole through the centre then you can make a simple arbour to hold the turret while you machine it.

Use a bar, as chunky as will fit well into the jaws on your lathe and be smaller than the diameter you wish to turn the turret to. make a section of it the same dia as the hole through your turret and then make a thread on the end of that so you can hold the turret on with a nut.

Or a threaded hole all the way through just screw the turret on and start machining. (you might want to centre drill it and use a live centre for support?)

If you were not making the hole all the way through then a threaded hole for a 10mm thread on an arbour would work too, just make sure the arbour has enough meat for the turret to butt upto when screwed on. (larger dia arbour helps for stability without a tailstock centre for support...)

This next bit might sound obvious but I have to say it. Keep the turret on the arbour as close to the chuck as possible to prevent undue flex and subsequent uneven/tapered finishes.

If you need a crap-o-cad to aid in my ramblings then I'll sort that in the morning. Getting sleepy! (just proof read this and edited it 5 times... my brian is faulty this time of night!)

Looks like you have a plan anyway.... :thumbup:

Have fun,

Ralph.

MadNick:
Ralph,

Thanks again for your help. I was pretty certain that an arbor was the answer - I suppose that in this case I would want to use a blind hole although cant see why I am unable to use a threaded bar the whole length of the turret.

Ill have another crack at this tomorrow and see what I can produce.

@Adam - good spot and yes it is a Barker, quite rare apparently. I keep wanting to strip it down for a refurbish and a coat of paint but it feels like I need to buy another lathe first in case anything needs to be made - does yours have the original top slide?

Nick

Divided he ad:
The blind hole on mine is used to set the tension between the turret and the base.

You make the fixing screw too long and then fully tighten it, check the play in it, remove the screw and file/emery off a little from the end. Then repeat until there is a full range of movement and no discernible play felt (feel is the only way to set these up IMO. )

Right.... Xmas shopping here I come! :loco: :lol: Luckily only 2-3 little things from one shop left to buy :ddb:

Hope that today's endeavours go to plan :dremel: (I'm in my workshop later trying to make a few other Xmas gifts before 15:00! Wish me luck :borg:)

Ralph.

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