Something special coming in issue 253 of MEW

You need one of these.

Is this real or "virtual" ? It looks like a rendered Cad drawing, so may not actually exist ?

it appears to be a commercial worm reduction box with, maybe, a ratchet positioning system in the plate bolted on the front behind the turret ? How does it clamp ? More details would be nice !

Nigel B

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That looks tidy, John

... Do you have any detail of the innards ?

Presumably a worm gearbox, but the spindle-locking arrangement might be interesting.

MichaelG.

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Edit: Nigel got there before me.

Edited By Michael Gilligan on 07/03/2017 09:01:24

Not much different to what you find on a basic Emco compact 5 CNC, just built up with plate and a few more tool positions

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Thanks, Jason

That said; I've never seen inside a "basic Emco compact 5 CNC" and my question remains open.

MichaelG.

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P.S. [for Richard] ... This might be useful:

http://www.denfordata.com/bb/viewtopic.php?t=4118

Edit: at about 2min 10sec ... This video shows the indexing latch:

https://m.youtube.com/watch?v=UR1x8yFYUeg

Edited By Michael Gilligan on 07/03/2017 09:32:50

There's a very good build thread over on HMEM of an 8 position lathe tool turret with downloadable pdf plans.

Michael I was just pointing those interested in where they may want to look then they could come up with something to suit. But for you here is the ratcheting detail and I'm sure the gearing can be found on the net too. Could also mount the motor along the lathe axis and use spur gears or toothed belt rather than a right angle drive, maybe a one way clutch in there somewhere so the tool can settle onto the ratchet. Ratchet is not a lot different to Emgee's method in Graeme's link

Absolutely fascinating. Thanks for that. I do like the manual turret version shown at the end.

Regards,

Richard

That picture is a rendered version of an early tool changer.

As these are proprietary I'm not at liberty to share the current design but they differ quite a lot from the rendering and the prototype which was built over 8 years ago.

**LINK**

These are no longer controlled by stepper motors but by a 24v 3 phase motor running through a special controller that allows it to go immediately to any tool number in any direction in seconds.

These are very expensive units hence my remark to Richard but I knew he's want one made from a bean tin for tuppence with a 3p off voucher but the end customer is very pleased with them and they don't work for peanuts either.

Most units ship with at least 3 spare tooling plates, one even shipped with 10 so the end user can leave a plate setup with tool and just swap plates and programs for different jobs.

Some have a mixture of lathe tools and boring bars, some all lathe tools and some all boring bars, you can play mix and match.

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Thank you, Jason ... but it wasn't really necessary to do anything especially "for me" ...

When I wrote "my question remains open" I was referring to my question [addressed to JS] about the unidentified "you need one of these" item.

MichaelG.

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P.S. ... For the avoidance of doubt: I have read John's subsequent post and I accept that he is not at liberty to disclose further detail.

Edited By Michael Gilligan on 07/03/2017 14:21:30

What?!? Only 3p off!?!

I suspect John knows me better than I'd like. It could well be I'm trying to do something that is beyond what I can afford, really, but that's no reason not to try.

Regards,

Richard.

That detent pawl looks a bit poorly...

Neil

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... designed, ... made, ... treated

MichaelG.

As in feeling sorry for itself, surely it's split right through to the locating pin.

Neil

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Yes, Neil ... I did notice that:

My 'multiple choice' was meant to be by way of analysis.

MichaelG.

Neil,

Just got my copy. Very interesting design. Thanks for doing this, very much appreciated.

Regards

Richard.

Thanks to Alex, really

Neil

253 Just arrived here in rural Oz. Lovely article and drawings. Just like the good old days and good to see. Has inspired me to make one myself, perhaps scaled down to 75mm diameter to match the Mighty Drummond's MT1 talistock taper though.

One minor quible; the text seems to me to say the tapered arbor has a 10mm thread, while the drawings call out 12mm, which seems "more correct" by eye. I think the space dedicated to the one build article, complete with drawings was well worth it and is getting back to more like how the mag was in its early days, which is not a bad thing. Seems like as drawing has gotten easier with CAD over the years, fewer people are doing drawings!

Will issue 254 include a small triangle to cut out and paste into the hole left in 253 where the piece to stick on the cover of 252 came from?

At the moment I can't see anything in my future work that would require an automatic tool changer for my lathe. I can see the appeal for someone who wants to make 400 super special, identical hinge pins for a tracked scale model.

For the occasional use I can envision a simple tool changer that is manually moved to each position. All that would be required in the CNC code is a pause using M0 with a comment saying something like "change to 60° threading tool then press cycle start". I don't think my quick change tool post is quite up to the repeat accuracy required but that may not be the case with all of them. This is similar to the tailstock turret system where the required tool is rotated into position by hand as it is needed.

Regarding the pawl in the earlier picture I thought there was a possibility that there was dirt on it that looked like a crack. I also think it looks a little too slender for the loads that will be imposed on it and if not already cracked then it would probably happen at some point in the future.

Martin C.

See my Album for more pictures of the manual 8 position Tool Turret mentioned earlier.

.Emgee

Martin, thats exactly how I use the manual Turret pictured above, time between tool changes is less than 10 secs including the moves off the job and back to cutting position.

It is recommended for users of the Emco 5 cnc turret that the locking plate is replaced with something thicker than 3mm, there is plenty of room for a 6mm thick plate if you want to go OTT.

In use the motor driving the toolchanger is constantly ON, after rotating to the tool position the 12VDC motor reverses at a lower voltage to drive the pawl onto the locking plate and the motor remains ON but at the lower voltage of 6VDC

Emgee

added para

Edited By Emgee on 13/04/2017 14:25:46