Screwcutting Clutch for Myford Lathes

[CymroParticipant @cymro]

Hi all,

Sorry to resurrect an old(-ish) thread but I wondered of anything ever became of Bob Mc's Arduino controlled leadscrew article? I gather there was one published in Issue 240 of MEW but I understand it was from a different contributor.

[Neil LickfoldParticipant @neillickfold44316]

Well, I was going to make up a clutch arrangement. But in the end, I just use a micro switch on the VFD and 220 3 phase electric motor. When the micro sets off, the motor stops. I then wind in the appropriate direction to remove the tool from the work piece, hit reverse and then repeat. At about 200 rpm it stops every time to within 0.1mm I have the VFD breaking the motor to a complete stop in about 0.5 seconds I think. If you try and stop too fast you can unscrew the chuck off the spindle.

Neil Lickfold

[Ian S CParticipant @iansc]

I don't know if anyones mentioned this one. Some years back in ME there was an article on using the magnetic clutch from a car AC unit in the jack shaft of an eastern manufactured lathe, although it could have been a lathe from any where.

Ian S C

[Bob McParticipant @bobmc91481]

In response to Cymro..

I don't know if this post should be in 'Screwcutting clutch for Myford's' … my apologies to Neil Lickfold.

There was a forum discussion about some aspects of using Arduino's for controlling the leadscrew … see 'Syncing up Arduino's'… the article was in MEW issue 240… this was my own design and was really an overview of what I did to my 70 year old lathe in order to get round the problem of providing a screwcutting facility and motion control of the leadscrew since the back gearing on this lathe did not exist and the original leadscrew was worn out.

In the space and time I had available for the article some of the features were not really covered, such as the fact that there is no encoder as such and the design is probably the most cost effective way of solving the problem when faced with the choice of buying a new lathe or having a go at re-modelling an old lathe.

Since I made the controller quite a few years ago there have been improvements and a re-thinking of the original design as I understand that only one processor is now needed to provide the signals for the leadscrew and headstock motors so that connecting (syncing) the two Arduino's is not needed.

I am not pursuing this re-design as I am very happy with the control unit I have, it works a treat and I have made quite a few threaded items, the only problem I have had is that the headstock stepper driver motor is underpowered somewhat and care needs to be taken to ensure that the cuts are not too heavy and the threading tool is sharp.

The 'different contributor' you mention was probably Chris Gabel who wrote a great article about using the Electronic Leadscrew Groups device (see iss 235 MEW), and I have no doubt that this is a much better system than the one I designed, and as he mentions there is plenty of backup from its vast member base, however this is not a cheap option and I would argue that the cost of applying the system to an old lathe needing refurbishment should be considered against the cost of purchasing a new lathe.

Well I'm happy to answer any questions you may have…

rgds…Bob.

[CymroParticipant @cymro]

I'm interested because I have a lathe which had no screwcutting capability from new and I keep getting a hankering to fit it out so that it does.

It's a Hector (you can see one like it on Tony Griffiths' site) which I bought a few years ago as part of a 'bundle' with a milling machine. I'm working to improve the lathe a bit at a time, as the mood takes me – I converted the feedscrews to ball thrust bearings last week – and think that it would be a much more versatile machine with screwcutting facilities.

I had thought to build a miniature screwcutting gearbox based on the Norton-type gearbox on my 12 x 36 Atlas, but the idea of an Arduino-controlled leadscrew appeals more, hence my wondering if the article had ever made it into print.

Thanks for the info about your setup Neil, but I've got some way to go before I'll need anything like that!

[Michael GilliganParticipant @michaelgilligan61133]

Bob Mc,

It's good to know that your design continues to perform to your satisfaction.

… I thought it was very cleverly done, and intend build something like it for my little 'Jason' lathe.

MichaelG.

[Bob McParticipant @bobmc91481]

Thanks Cymro, Michael G…

… I have now fitted a DC treadmill motor to the lathe, so its features are … forward/reverse spindle, variable spindle speed, screwcutting any thread…and slow to fast leadscrew motion; all these functions available without changing gear wheels or having to listen to metal gear clanking noises.

will post some pics…

rgds…Bob. underneath… lathe now with homemade pulley cover…. the black box on top is for rpm readout…not got round to that yet..!

Fitted to lathe.. a 20tpi inside thread mandrel nut I made using the screwcutting feature.

[Michael GilliganParticipant @michaelgilligan61133]

It looks great, Bob

MichaelG.

[clogsParticipant @clogs]

Hi Bob Mc,

what a fine machine u have…….

looks like u have to much time on ur hands..hahaha……….

wish I could keep my place as smart…….

Looking forward to the aricle……

Men in sheds rule…..Clogs

[Bob McParticipant @bobmc91481]

Thanks Cloggs…

It is true that I do have more time on my hands nowadays but after 50 or so years of working I need a break!!

Thanks for noticing the workshop is reasonably clean, but if you have ever suffered from the 'gremlins' which hide tools and bits as other members of the model engineering fraternity have mentioned, then the only option is to tidy up and in the process SOME of the stuff will be found!!

By the way there is no future article about the machine, there was however the original article about using Arduino processors for the screwcutting and leadscrew control of the lathe….see MEW issue 235.

I try to keep busy as best I can and on those cold rainy days I could sit in front of the telly and watch Parkinsons adverts for funeral insurance …. you get a free pen you know…just what everyone is in dire need of..!

I have been busy re-making a binocular reflecting telescope as well as fixing up the lathe and doing other things…will post some pics…

all the best rgds Bob.

[Neil WyattModerator @neilwyatt]

Posted by Bob Mc on 10/12/2016 15:53:02:

Now that looks fun

[Bob McParticipant @bobmc91481]

Hi Neil…

The 2×6 inch scope has turned out to be better than expected, I would say its similar in image quality to an 8 inch reflector but with a more comfortable viewing situation.

I had some problem with the original stand because although it was easy to look down into the eyepieces when the scope was pointed in near vertical positions, but when oriented horizontally I had to crouch down to get to the eyepieces which made any observation uncomfortable. So after much searching and deliberation I bought an auto gearbox lifter and altered it …. I can now adjust it eyepiece level to suit the height of the observer and the altitude of whatever is being observed.

The Azimuth bearing is the actual ram support of the unit and is surprisingly smooth, I fitted a manual slow motion drive to the Alt bearing for fine tuning, this is coupled by a magnetic yoke to the OTA's Alt support so that at any time one can 'grab' hold of the tubes and move it about.

Will post some pics ..

rgds….Bob.

[Bob McParticipant @bobmc91481]

As promised some more pics of 2×6 inch reflecting binocular scope..

nb…..Sorry I seem to have taken over this thread …. my apologies…

I forgot to mention that collimation of the two mirrors can be done whilst observing, this is a necessity as I have to trundle the scope across rough ground and it gets a good shake up every time..

The pics… rgds….Bob.

Collimation adjustment knob…right tube.

Mirror Cells collimation adjusters.

Inter pupil distance adjuster.

A look down the eyepiece end.

Slipping magnetic clutch

[Nick HulmeParticipant @nickhulme30114]

Posted by Chris Trice on 28/02/2015 11:41:30:

So because one guy did it to your personal lathe, which obviously irritated you, all owners of Myfords have to be tarred with the same brush John? Your previous machinery ownership is completely irrelevant. It read as a smug swipe at all Myford owners. Sorry, but it did.

As a Myford Super 7 owner of 20 or more years standing I can confirm that the first post was funny and that you are far too sensitive, you only have to briefly trawl the net for Myford related threads to find owners agonising over the 'year correct colour' to paint it and the right filler to use before painting and if that don't make ya smile nothing funny will.

Although mine was the correct colour this was simply because it still had the original paint, but it's a Lathe, the colour doesn't matter, what it does is what matters 😀

Nick

[Neil WyattModerator @neilwyatt]

Posted by Bob Mc on 10/12/2016 22:14:45:

As promised some more pics of 2×6 inch reflecting binocular scope..

nb…..Sorry I seem to have taken over this thread …. my apologies…

I forgot to mention that collimation of the two mirrors can be done whilst observing, this is a necessity as I have to trundle the scope across rough ground and it gets a good shake up every time..

The pics… rgds….Bob.

Collimation adjustment knob…right tube.

Just spotted this Bob, very impressive!

Neil

[Author]

Posts