Ball Turning Tool

[SquarepegParticipant @squarepeg]

[SquarepegParticipant @squarepeg]

Hi, has anybody had any issues with mounting a ball turning tool to their lathe? I have a Chester DB8VS lathe and recently purchased a ball turning tool from RDG. However it doesn't fit, as the centres on the lathe are about 5mm inboard of the centres in the ball turning tool. I did assume that the centres would all be standard as they are never given on the tools description so I just took the chance and rather annoyingly it didn't pay off! When I remove the topslide, the lathe has 85mm centres and the tool has 90mm so it's really close, but just won't fit properly. Is my only option to open up the holes on the tool or is there an easier way, surely I can't be the only person to have hit this problem but I can't find anything from a forum search. Ideally I don't want to have to open the holes up because the tool doesn't rotate on a central pivot, but on the 2 mounting bolts so could end up very easily not sitting central about its rotational axis. I don't think there's an easy option but it's worth asking in case I'm missing something.

Thanks

[Martin ConnellyParticipant @martinconnelly55370]

Is there enough available vertical adjustment to put an intermediate plate between the lathe and the tool?

Martin C

[SquarepegParticipant @squarepeg]

Posted by Martin Connelly on 11/10/2021 15:54:31:

Is there enough available vertical adjustment to put an intermediate plate between the lathe and the tool?

Martin C

Sadly no, sorry I should have made that clear as that was my first thought too. Good call though thanks.

[John HinkleyParticipant @johnhinkley26699]

I'm not entirely sure if I understand the problem, but my initial thought was whether it would be possible to mount the ball turner on an angle plate or vertical slide and operate it that way at 90 deg to its intended orientation ? Can you post a link to the ball turner that you purchased?

John

[SquarepegParticipant @squarepeg]

Hi John, I should have posted a link to the tool at first as it'll be clear when you see it.

This is what I purchased

That's an interesting idea, although I'm not sure it'd work with this type of tool.

I may have to take the hit and just buy a different type of tool. I just find it really odd that I'm the only person to have hit this problem.

Thanks

[martin haysomParticipant @martinhaysom48469]

how about re maching the face the insert locates on looks like there is plenty of room to lower it 5 mm

[Tony Pratt 1Participant @tonypratt1]

Posted by martin haysom on 12/10/2021 09:11:05:

how about re maching the face the insert locates on looks like there is plenty of room to lower it 5 mm

As Martin says if the insert is 5 mm too high just lower it.

Tony

[SquarepegParticipant @squarepeg]

Posted by martin haysom on 12/10/2021 09:11:05:

how about re maching the face the insert locates on looks like there is plenty of room to lower it 5 mm

Sorry gents, maybe I've not explained the problem well enough. My problem is that the mounting holes for the tool are 90mm centres and the mounting in the cross slide is 85mm centres.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Tony Pratt 1 on 12/10/2021 09:16:57:

Posted by martin haysom on 12/10/2021 09:11:05:

how about re maching the face the insert locates on looks like there is plenty of room to lower it 5 mm

As Martin says if the insert is 5 mm too high just lower it.

Tony

.

I think it’s the spacing of the holes that’s troubling Squarepeg, not the tool height.

[quote]
When I remove the topslide, the lathe has 85mm centres and the tool has 90mm so it's really close, but just won't fit properly.

[/quote]

MichaelG.

[Martin KyteParticipant @martinkyte99762]

The centre hight may not be given directly but it does say it is designed for the Myford and may be used on other larger lathes. The centre hight of a Myford over the boring table (Cross slide) is 2 1/16" or 52.38mm. You do seem to have a higher centre hight over your bed but just from the photo's the carriage and cross slide seems to be somewhat taller than the Myford. The tool is designed to go on the boring table.

Where are you mounting the ball turning tool. Not on the toolpost seating are you?

regards Martin

[SquarepegParticipant @squarepeg]

Posted by Martin Kyte on 12/10/2021 09:25:55:

Where are you mounting the ball turning tool. Not on the toolpost seating are you?

regards Martin

I'm removing the top slide, with the tool post attached and trying to mount directly to the top slide mounts on the cross slide. The 2 mounting bolts sit in a circular groove that allow the top slide to rotate.

[Michael GilliganParticipant @michaelgilligan61133]

.

90mm centres on the tool

MichaelG.

[SquarepegParticipant @squarepeg]

Thanks for clearing that up Michael.

I'm still trying to figure out how to post images. It seems pretty clunky by todays standards.

[Michael GilliganParticipant @michaelgilligan61133]

You’re welcome 

Try starting here: **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=103028&p=1

A photo of your cross-slide would be a good start

… the exploded view in Chester’s manual isn’t very useful.

MichaelG.

Edited By Michael Gilligan on 12/10/2021 10:11:42

[DaggersParticipant @daggers]

I had a similar problem on a similar ball turning tool, just drilled two new holes at 90deg to the existing ones.
Would that work for you?

[Adrian 2Participant @adrian2]

Squarepeg, it sounds like you want to screw the tool down utilising two tee slots which would be best I think.

However can it not screw down into just one slot ie two screws into the one tee slot ? You will be taking light cuts I would think.

Just a thought.

Adrian.

[AndrewDParticipant @andrewd]

Is there room to drill out the mounting holes and replace with eccentrically drilled plugs?

[SquarepegParticipant @squarepeg]

Thanks again Michael, I will have a look. I'm in work at the minute so can't get any pictures yet.

Posted by Daggers on 12/10/2021 10:36:59:

I had a similar problem on a similar ball turning tool, just drilled two new holes at 90deg to the existing ones.
Would that work for you?

Daggers, that's probably the best shout. I'd considered opening up the current holes but not just re-drilling new ones in another position, I guess it doesn't actually matter where they go as the bolts slide in the slots anyway. The holes will get close to that upper (smaller diameter) portion of the tool but I could always bring it in work and get it CNC milled to put a clearance cut in that bit as a drill would just wander when it hits the edge and I need to be able to get a nut on too. Thanks for the suggestion, it's good to know other people have had similar issues.

[SquarepegParticipant @squarepeg]

Adrian, they're not T slots, they're circular slots that allow the usually mounted top slide to rotate. I have no T slots. Thanks for the suggestions though.

Andrew, another good suggestion that I hadn't even thought of thanks, that could definitely work.

[duncan webster 1Participant @duncanwebster1]

There doesn't seem to be any reason why the holes have to be symmetrical, so can you just drill a third hole on the same pcd but moved round a bit so it is 85 from one of the existing

[SquarepegParticipant @squarepeg]

Posted by duncan webster on 12/10/2021 13:37:20:

There doesn't seem to be any reason why the holes have to be symmetrical, so can you just drill a third hole on the same pcd but moved round a bit so it is 85 from one of the existing

Good point Duncan. I have been debating if it needed to be central. At first I assumed that it rotated on the mounting bolts in the same way that the top slide does when they are loose. However, on second thought (I haven't got the tool to hand and can't remember) it must rotate about it's own axis on an internal bearing/close fit. Therefore, as you say, it wont matter if it doesn't sit symmetrically on the cross slide.

Thanks for all your help guys, much appreciated.

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