Lathe crash!

[ChrisBParticipant @chrisb35596]

Posted by JasonB on 01/01/2019 16:29:01:

I tend to cut away from the chuck at the back so don't have to worry about stopping in a rush if going to a shoulder and can cut faster so can stop easily and run in other direction to take me back to the start.

Would that mean inverting the tool upside down like in this video ? **LINK**

 

Posted by Chris Trice on 01/01/2019 18:27:23:

 

What about a retracting cutting tool or one that swings up out of the way?

Good idea Chris/Michael, would make a nice project – I just need time, sometimes I wish a day was 48hrs!

 

Posted by Ian Skeldon 2 on 01/01/2019 17:09:46:

 

maybe buy a load of bushes and hope you never need them

Should not need any bushes anymore if my planned mod works out…but I'll keep a couple of spare keys just in case

 

Bushes and keys – the key is aluminium so there's an easy fix failsafe should I mash up again. Bushes are 8mm dia instead of the original 10mm – not sure of the material, could be stainless or titanium as I mage them from a bolt which conveniently was the exact outside diameter.

Conveniently used a 5/16" cres bolt which fits perfectly on the 8mm bushes. Added a grease point for lubrication and rethreaded the bolt to M6 to fit the T-nut on the banjo.

Bushes are a sliding fit on all gears, so there'e no more tapping to force them on. As the gear bores are not exactly uniform some fit a bit tight while some slide right on but none are loose or hammer tight.

The gears will slide right off the shaft when the retaining washer is removed ( it will either be a c-clip or two halves) so I won't need to take the whole thing apart.

Will see how this works, and maybe post a video if it runs ok.

Edited By ChrisB on 01/01/2019 22:04:49

[Michael GilliganParticipant @michaelgilligan61133]

Looking good, Chris

MichaelG.

[ChrisBParticipant @chrisb35596]

Tried and tested the new bushes this week and found some time to take video. It's working fine till now. Cut some M16x2 threads and changed back gears for normal turning with auto feed.

Now time will be the real tester!

[ChrisBParticipant @chrisb35596]

Posted by JasonB on 31/12/2018 20:32:52:

But the whole reason Chris had a crash was because he did not want to disengage the nuts, what use is a system to disengage them, he could have just flipped the lever and drilled his hole if he could disengage them.

I'm assuming the Meek clutch will mean you loose your position when cutting say metric threads on a machine with imperial leadscrew.

Regarding thread cutting metric threads on imperial lathes, I cannot disengage the half nuts otherwise I'd loose my position – I have noticed that I can switch the feed direction knob with the lathe running at the lowest speed without any rattling of the gears (at 3:18 in the above vid clip I'm switching directions)

Has anyone tried this before, and is it recommended? I'm tempted to give it a try on my next thread cutting project.

[JourneymanParticipant @journeyman]

ChrisB, I would have thought that going directly from forward to reverse is likely to impose an undue strain on the electronics. Better to stop in between, also you still need to retract the tool before going into reverse so some frantic handle winding at the same time as flipping the reverse switch, an exercise in co-ordination

(On another matter, I note from your video above that you wear a ring. NOT a good idea in the workshop always told not to during my training days and shown the gory pics to go with the advice!)

John

Edited By Journeyman on 11/01/2019 16:57:47

[ChrisBParticipant @chrisb35596]

I guess that would be correct if I flipped the electric direction change over switch on the top control panel. I'm referring to the feed direction selector knob (which is mechanical) on the lower part of the headstock. The direction of rotation of the motor and chuck remains the same, what changes is the direction of movement of the carriage. So let's say I'm cutting a LH thread – I turn the feed selector to the left and start cutting, when the cutter is up to the shoulder I switch the feed selector to the middle position and the feed stops, I can then retract the tool and switch the feed selector to the right, and repeat the process…don't know if I'm explaining myself properly.

You're right about the ring John, thanks for pointing that out…have to make a habit of taking that off

Edited By ChrisB on 11/01/2019 17:26:58

[JourneymanParticipant @journeyman]

ChrisB, must admit I've never tried that on my WM250. But when stationary the feed change knob always seems to be clunky and sticky always have to check that it is not still in neutral. Having had the gearbox cover off the gears are fairly crude but if it works why not. I can recommend a flip-up tool holder when screw-cutting.

John

[BazyleParticipant @bazyle]

Using the 'tumbler reverse' will lose your registration of the spindle and leadscrew because it is changing some gears around.

[JasonBModerator @jasonb]

It has no tumbler but I think the effect of using the front gearbox will be the same, Will look into it a bit later and get back to you, need to find my photo of whats inside as it is a while since I opened mine up.

If I want to cut on the back stroke I tend to go from fwd, pause in neutral and then into reverse which seems kinder to the lathe

Edited By JasonB on 11/01/2019 18:21:10

[ChrisBParticipant @chrisb35596]

As Bazyle predicted, it does not work this way. I tired cutting a test thread to see if the next pass aligns to the first pass after disengaging through the feed selector knob – it does not align at all, it's similar to disengaging the half nuts…

I have something else in mind which might work, something which Andrew Johnston pointed out in a post above, about moving to the exact position original starting point…

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