ML7 Crossfeed direct reading?

[Chris TriceParticipant @christrice43267]

The problem has always been the top slide because it can be angled. Should it match the cross slide or the leadscrew? The metric Myfords have the index dials marked in 40 divisions (plus half divisions) and the feed screw pitch is 2mm so both sets of dials indicate the total removed from the diameter rather than the actual slide movement. I found printing up and laminating a sheet with a visual reminder kept near the lathe helps keep it clear in your head when planning precision work.

[John HaineParticipant @johnhaine32865]

My understanding is that as standard metric lathes read in "diameter" mode and imperial in "radius". Myford imperial lathes are I understand "radius" but my metric Super 7 is "diameter", but the lead screw is 1/8 inch pitch!

[Neil WyattModerator @neilwyatt]

> Maybe we need a nice little MEW project to make quickly interchangeable dials; so that you can use the appropriate dial for the job.

I think Jason spoiled that idea with 'fit a ring over the top', although I'm sure some creative could could send me a 15-parter on the subject!

Neil

[Anonymous]

Posted by John Haine on 12/12/2014 21:06:49:

My understanding is that as standard metric lathes read in "diameter" mode and imperial in "radius". Myford imperial lathes are I understand "radius" but my metric Super 7 is "diameter", but the lead screw is 1/8 inch pitch!

Ho hum, looks like I've got an odd lathe, my imperial lathe reads diameter on the cross slide.

Andrew

[AndyPParticipant @andyp13730]

I have always been confused by the assertion that metric lathes read in diameter mode on the cross slide since I have 3 metric lathes, a Boxford AUD, a Sieg C1 and a Cowells ME90 all of which read in radius mode on the cross slide – anything else would annoy the hell out of me!

Andy

[John OlsenParticipant @johnolsen79199]

Well, the metric Unimat three has the cross slide graduated in radius, so it looks like exceptions are the rule. I suspect that may be the case for other Emco lathes too, since they are often used with a milling attachment. This uses the cross slide as the Y feed, so calibrating in diameter would be confusing.

John

[John Stevenson 1Participant @johnstevenson1]

All my lathes are diameter mode.

So are all my drawings

So are all my DRO's

Wwhich then leads me to ask if you have a radius dial on a machine do you program the DRO to also read in radius ?

[Chris TriceParticipant @christrice43267]

It doesn't actually matter which mode your lathe has as long as you're aware of it. The maths isn't difficult.

[John Stevenson 1Participant @johnstevenson1]

Chris, with respect if you have to do any maths even divide by two then errors come into it.

After working on more lathes over the years that I can shake a stick at a few things I have noticed but not exclusive.

The bigger the lathe the more chance it's in diameter mode.

European lathes tend to do diameter more than small lathes or American ones.

Lathes like the Myford probably went radius as it's hard to do diameter dials on small machines due to size restraints and dropping the pitch from 10 to 20 means it wears out quicker.

[Chris TriceParticipant @christrice43267]

My Myford is metric and is indexed for diameter. I suspect it's more about a convenient number of division engravings on the index wheel. Complicated maths I can understand people making mistakes but how difficult is it to remember to put on a .010" increment to take a total of .020" off the total diameter. It's not exactly rocket science.

[John Stevenson 1Participant @johnstevenson1]

Chris,

Not difficult if you only have one lathe but if you are moving between different machines where some follow radius and some follow diameter then it becomes harder and mistakes are easily made.

Also over shoot and put .0105 on and you have removed .021, easily done on small crowded dials and not conversant to say a bearing fit.

As regards it being rocket science I can't comment but I can ask my girlfriend who is a genuine certified, letters before and after her name, rocket scientist.

[Roger Provins 2Participant @rogerprovins2]

When I first had a lathe I used to often make this mistake by dialling in the wrong amount. So, as a test without actually altering anything, I made up a re-calibrated strip of paper which I attached to the dial. It did help but when it eventually disintegrated I was more used to lathe work and just reverted to using the dial as is.

Edited By Roger Provins 2 on 15/12/2014 05:34:08

[Chris TriceParticipant @christrice43267]

Roger hits nail on head. Someone reasonably conversant with the working of a lathe shouldn't have a problem. It's possible to make the same errors in radius or diameter mode. Being mindful of anything you're doing (measure twice, cut once) is the solution to not making mistakes. A DRO is the most obvious solution for the confused.

[BazyleParticipant @bazyle]

I'd hate to have a mix of dials so hats off to Jason's simple renumbering. Anyone else have a mix of cars with the windscreen wiper on differnet sides so they occasionally clean the screen before turning a corner.

I was wondering if this applied anywhere else where non intuitive scales could be used.
How about measuring jugs that show you how much volume is left before it overflows. This could also apply to a car fuel tank to indicate how much a top up was going to cost. When you check your oil you don't measure how far it is up from the bottom but how far it is below the full line.
Then a lot of people seem to need a drill/mill quill feed that shows how much space is left before they hit the table.
I recently heard of a person who sets his alarm clock to tell him when to go to bed so he gets enough sleep instead of forcing himself up too early for his body clock wakes him.

 I don't have a lathe DRO but do you set the cross slide one to show zero at centre and do the maths or do you zero it on the current diameter so you can 'dial in' a particular depth of a shoulder?

Edited By Bazyle on 15/12/2014 13:56:03

[Neil WyattModerator @neilwyatt]

> I recently heard of a person who sets his alarm clock to tell him when to go to bed so he gets enough sleep instead of forcing himself up too early for his body clock wakes him.

I have an irritatingly accurate body clock. It's not getting a lot of use as the puppy is running 45 minutes fast

> I don't have a lathe DRO but do you set the cross slide one to show zero at centre and do the maths or do you zero it on the current diameter so you can 'dial in' a particular depth of a shoulder?

It surprises me how few people do this, especially with digital callipers.

Neil

Edited By Neil Wyatt on 15/12/2014 14:14:19

[Nick WheelerParticipant @nickwheeler]

Considering that drawings tend to give the required diameter and that your ruler/caliper/micrometer measures the diameter, why would you want the dial to read radius?

[V8EngParticipant @v8eng]

I too have a good body clock, excepting for a few weeks every Spring and Autumn, when the Politicos tell us that time must alter by an hour.

[John Stevenson 1Participant @johnstevenson1]

Posted by Neil Wyatt on 15/12/2014 14:12:19:

I have an irritatingly accurate body clock. It's not getting a lot of use as the puppy is running 45 minutes fast

Neil

.

LOL, All time classic that one, this year is nearly over but it's bot to be one of the better ones.

[MuzzerParticipant @muzzer]

> I don't have a lathe DRO but do you set the cross slide one to show zero at centre and do the maths or do you zero it on the current diameter so you can 'dial in' a particular depth of a shoulder?

It surprises me how few people do this, especially with digital callipers.

I set my digital calipers to the final dimension I want, then zero the display. Then I take a skim of the work piece with the cross slide dial set to zero and measure the resulting actual diameter of the work with the calipers. The indicated distance tells me directly how much more diameter I need to remove. When the work piece is reduced to the point that the calipers display zero, I'm there.

My Bantam cross slide dial measures directly in mm diameter increments, so I can now dial in the required additional cut directly. If I'm feeling paranoid, I can take several cuts and confirm that I am approaching the final diameter from above by using the calipers after each cut.

I normally work in mm but if the diameter is imperial, I set the required imperial diameter on the calipers, zero it and then swap over to metric display.

If I had a "radius" indicating dial, I'd have to take my chances at halving the number between the caliper display and the cross slide dial. Halving numbers is something I can still usually manage but it doesn't arise with the Bantam.

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