Eccentric’s “Turnado”

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Eccentric Engineer on 20/07/2018 08:34:43:

Hi All

Just thought I'd clear up a slight misunderstanding about the brown colour of the Turnado tool posts.
They don't come from the casting plant like that; after I machine them I send them for a black oxide surface treatment and that's how they come back.
Steel turns jet black in a few minutes but for some reason cast iron only goes a deep brown < etc. >

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Thanks for the useful clarification

MichaelG.

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Edit: idle curiosity has just led me to find this discussion: https://www.finishing.com/26/97.shtml

Edited By Michael Gilligan on 20/07/2018 08:59:47

[John HaineParticipant @johnhaine32865]

Well I was really interested by this thread and thought it would be nice to have something like this for my little Unimat. I didn't want to fit it on the Myford because the toolpost doesn't get moved off that unless I really can't avoid it since all the tool calibration would be wrong. Unfortunately the official versio won't fit such a small lathe, and having just made a tangential toolpost/holder I thought it might be neat to make my own miniature version.

I found this nice steel plate with the two faces turned flat and parallel in the material I inherited from my dad – very dirty and a few dings but cleaned up nicely. Clamps to a bar under the bed with a csk M6 bolt. I thought that I'd need to mill a vee slot on the underside but found that the small flat on the top of the "prism" of the front bedway is co-planar with the real way.

This is the tangential holder bolted down to a 1/2" brass block, also found lurking in the scrap box and machined all over, and down to a thickness to bring the tool tip easily to centre height. Brass slides easily on the steel plate. Note that the block projects under the tool tip so there's no tendency for it to tip when cutting.

First attempt at turning a bit of brass rod (after sucking up all the swarf).

So I feel slightly bad about copying at least the principle of Gary's design but couldn't have bought one to fit anyway. I can feel a pen coming on…

[Michael GilliganParticipant @michaelgilligan61133]

That's excellent, John

MichaelG.

[Ian S CParticipant @iansc]

I think the colour of the cast iron is not caused by the lack of carbon in the metal, but by the excess of free carbon, what ever, I like the colour, hope it is durable.

Ian S C

[OuBallieParticipant @ouballie]

Posted by Ian Parkin on 19/07/2018 22:10:22:

I had never realised that cast iron would come out of the mound looking like this …die cast yes but not cast iron…I cant imagine what causes the colour

Ian,

With the correct moulding 'sand' just about any but the finest detail will come out, provided the CI is up to scratch.

Geoff – What a wasted year I've had 😪

[VicParticipant @vic]

How is that working out John? I was thinking of possibly buying the Eccentric but it’s a lot of money for something that won’t be used that often. I have enough “lump” metal for the holder I just need to source some 1/4” plate. Sadly my tame local metal supplier doesn’t seem to stock it!

Edit: I’ve found some 5mm thick plate on the auction site. Should be about £10 for two bits of suitable size. Not sure how thick the original is but 5mm should be ok?

Edited By Vic on 04/11/2019 11:13:13

[John HaineParticipant @johnhaine32865]

To be honest I haven't had a chance to use it in anger since making it! But the quick trials I did were promising.

[VicParticipant @vic]

It seems to be ideal for curvy stuff that’s normally difficult to do on a metal lathe.

I need to check my metal stocks but I think I have all I need apart from the two plates – I like the Eccentric idea of using two plates to adjust the height. The tool post will most likely need to be in two pieces but I don’t think that will be a problem.

I would like the option to maybe buy some of the accessories though, anyone know what size the major diameter is of the pivot pin? I know the holes in the plate are 5mm.

[Andrew Moyes 1Participant @andrewmoyes1]

8mm nominal, 7.98mm to be exact.

[VicParticipant @vic]

Thanks Andrew, that was my guess.

[Nigel Graham 2Participant @nigelgraham2]

Just watched the video Jez cites…

Wonderful! I was thinking not just of the machining time itself, but the (possibly rather longer) time grinding all those tools. He must have used a tool-grinder to maintain consistent edge height across the range, to be able to use them freehand as he did.

Neat locating-blocks on the V-blocks, with the advantage of minimal machining of the blocks themselves. I'd be tempted to make them fit the T-slots so can be used equally well from a slot as from the table-edge.

I noticed the bench-vice seemed to have the rear jaw as the moving one. Not seen that before.

[Chris VParticipant @chrisv]

Good morning and hope everyone's doing ok.

Just read this thread as I'm just setting up mine, particularly interested in Andrew Moyes post (I've send you a PM Andrew) regarding an alignment tool I quote… I also turned up a vertical pin to fit in the holes in the bedplate. That enables the tool to be aligned with the centreline of the lathe when ball turning and allows the tool to be set to the radius of the ball.

Sounds like that's just what I need but I'm not proficient enough to figure it out myself…help please anyone?

Cheers

Chris.

[Andrew Moyes 1Participant @andrewmoyes1]

Here are some photos of the centring pin.

Andrew

Edited By Andrew Moyes 1 on 05/04/2020 11:40:36

Edited By Andrew Moyes 1 on 05/04/2020 11:41:26

Edited By Andrew Moyes 1 on 05/04/2020 11:41:57

[Chris VParticipant @chrisv]

Oh brilliant thank you so much Andrew!

So you align your vertical pin with the tail stock centre. Then measure between your pin tip and the tool tip for the required radius, adjusting as necessary the sliding shoe screwed to the base of the tool holder right?

Cheers

Chris.

[Andrew Moyes 1Participant @andrewmoyes1]

Yes, that's right. When you have aligned the centres, if you want, rather than advancing the cut freehand, you can use the crosslide feed. Align the centres, set the crosslide dial to zero and wind out the tool. Then you can start turning the ball and advance the tool using the crosslide until the dial goes back to zero. I found it’s important to lock the crosslide before each cut because you are pushing the tool into the workpiece and against the pivot pin. Otherwise the backlash in the crosslide feedscrew will catch you out.

Edited By Andrew Moyes 1 on 05/04/2020 14:09:04

[Chris VParticipant @chrisv]

Thanks Andrew, I think I understand that. Ive just started setting it up to try copy turning which I will get on with this week. Once that's done I will turn a centring pin and have a go at ball turning and see how I go.

Much appreciate your help!

Cheers

Chris.

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