Thread: Ball turning attachment - operation of

cross slide on mine .

johno

Hi Simon,

Normally, once you set the radius you don't change it, you start on the front and back corners, and advance the cross slide as you go. eventually you get the tool contacting all the way through the arc.

Not a very good explanation, and I'm not sure it applies to all type of ball turners...

Ray

Thanks guys. So I assume if you advance the cross slide too far then you make an ellipse instead of a circle?
So you need to make a mark of some description so you know when to finish?

Cheers,

Simon

More like an arc with a pointy end yes.
The up and over type have this adjustment on them as there is not a cross slide to crank in. As Ray says, you set your radius and then wind in the cross slide until you get the result you want.

Michael

you just take small cuts until the cutter is cutting in the middle of your job , by then you should have a ball , after that you are making a smaller ball , least thats how i do it .
i was going to try and describe the whole thing but have found out after typing and back spacing thats its not so easy to describe in words , so gave up . best thing is to watch a few you tube clips there are heaps of em .

johno

I'm not sure what Bobs is like but on mine, if your material is in the chuck and faced off and to size you should be able to kiss one corner edge of the work with the bit perpendicular to the work piece and then rotate the tool through 190º and kiss the opposite side when the bit is perpendicular again, that way you will know you will get a ball. If you kiss to early or too late you need to reposition the tool and the cross slide till they kiss on both sides. Then I don't touch the cross slide and just move the compound rest in a bit and rotate the ball turner through its arc.

Thanks guys. I have watched quite a few youtube videos but it's not that obvious what was being adjusted. The up and over type that act in a similar method to a boring head (similar to Michaels) seem to be adjusted by the radius adjustment. My particular attachment replaces the compound slide and sits on top of the cross slide.

Anyway, you guys have pretty much answered my question. Dial up the radius and leave it. Adjustment with cross slide as you go. That will mean that the radius adjustment can be at the chuck end and not be of any consequence. While not exactly the same, I have copied this design in principle:

Logan Lathe Ball Turner

I don't think mine will have the same finish as this one though I will try! I am planning on using a similar TC insert since I have a few that I don't have a holder for. They were given to me. I will also make a HSS holder for it in an attempt to give this tool a dual purpose, using it on a t&c grinder to grind profile tooling. That way I may get some more use out of it.

Simon

Simon,

You need to incorporate some sort of centring device in your design. I haven't and I need to.

BT

Originally Posted by Anorak Bob

Simon,

You need to incorporate some sort of centring device in your design. I haven't and I need to.

BT

Hi Bob, I assume you mean on the cross slide so that you don't advance the pivot point of the turner past the spindle axis? I originally thought you set the cross slide up in centre and then adjust the radius with each cut until you get where you want to go but I'm wrong. That would make it easy since you could set it central using a dead centre in the TS and the lock the CS. For those that have a DRO of any description, this would be a no brainer. The simplest way would be to centre the tool on the dead centre in the TS and note (or zero) the cross slide and then count how many turns you do backing out. Here we go, counting hand wheel rotations! I hated it on the mill and do on the lathe. looks like a good excuse to put a poor mans fro setup on the lathe! I guess a small witness line on the saddle lining up with another line on the cross slide would do. Zeroing the CS and the mark would be n easy way but a DRO would be better!

What are your plans Bob. I remember you saying that it's a tool that you will hardly use, so I guess there is every chance that you won't get around to it for a while since you probably have bigger and more important projects!

Simon

Hello Simon,

On mine there is nothing to align with the spindle centreline. A solution may be to bore a centre hole in the slide with the slide centred and make up a pointer that can be inserted in the hole, facilitating alignment. That does not though address the issue of setting the radius of the tool. The centring device could be independant of the slide, maybe perched on the body opposite the clamp and held in position with a thumbscrew?

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Bob.

Hi all,

Another request for advice: I'm wanting to cut a 60 deg dovetail for the tool slide. I know I could just do a rectangular channel but I want to make a dovetail! I have a small off cut of M200 which is 20mm thick which I plan on using for the tool post. Allowing for the parallel gib strip, I need to make a female dovetail in the top that will be about 23mm wide (give or take) at the base. Allowing it to be 10mm deep that means that the width at the top will be approx 11.5mm. I have been looking at dovetail cutters that will cut to the required depth but these will be so wide as to cut both sides with each pass, possibly putting too much load on the tool. I would prefer to cut each side of the dovetail separately. So, I am planning to cut the dovetails with an end mill and tilt the mill head to the required angle. Harold Hall does this in one of his milling books: Milling a Complete Course, where he describes how to make a boring head. The only issue I can see with using an end mill is that when you achieve the required depth, it creates a "channel" at each side at the bottom of the dovetail. This can be minimised by choosing a smaller end mill but there would be a compromise because a too smaller end mill would be inclined to flex.

BTW, I have a 12mm dovetail cutter, but it's only about 6 - 8mm deep. This would mean I would have to do the final cut in several passes. Not keen on that either.

Any thoughts?

Simon

I'm also in the process of making one, but copying Steve Bedairs design.
Pretty much the same thing, but not as 'flashy' !

Simon, use the shaper! Dead easy once set up.

Originally Posted by simonl

So, I am planning to cut the dovetails with an end mill and tilt the mill head to the required angle. Harold Hall does this in one of his milling books:

Not so sure you'll get in there without a chuck like his... or ER25 or smaller(of course you might have such). but I've been wrong before

Originally Posted by Anorak Bob

That does not though address the issue of setting the radius of the tool.

Once the slide is centered you can measure the radius from the center of a faced piece of material or the tail stock center. Or with Michaels you could use a height gauge(if you know your center height.

p.s I've been thinking about my set up a little more and wondering if a tangential tool holder might be an easier way to get what I was after. I hope I remember that next time I need to make some balls.

Originally Posted by jhovel

Simon, use the shaper! Dead easy once set up.

Might have to kick him out of the club if he keeps this up!

Stuart