JasonB | 12/12/2014 14:57:29 |
![]() 25215 forum posts 3105 photos 1 articles | You just need to renumber the dial, instead of 0, 10,20,30, 40, etc make one or fit a ring over the top that reads 0, 20, 40, 60........160, 180 and back to 0. So each small division will then be 0.002" off diameter. To try and get 0.001" divisions would really need a larger dia dial as the lines would get too close together.
My far Eastern Imperial lathe reads diameter not tool movement |
Mike Poole | 12/12/2014 15:53:14 |
![]() 3676 forum posts 82 photos | The Colchesters I have used (Bantam, Student and Triumph) all take off the diameter, I have just looked at a DSG type 15 and Herbert capstan, and the cross slide on both take off the radius. It looks you have to get used to what you have got as there is no standard. Mike |
Muzzer | 12/12/2014 16:00:40 |
![]() 2904 forum posts 448 photos | I can't see my Bantam from the armchair here but logically the topslide should have half the scale numbering of the cross slide, given that it spends much (most) of its time not perpendicular to the axis. Can anyone confirm on this or a similar machine? Murray |
Michael Gilligan | 12/12/2014 16:04:10 |
![]() 23121 forum posts 1360 photos | Both arrangements have their niche: Therefore, neither can be 'correct'. Maybe we need a nice little MEW project to make quickly interchangeable dials; so that you can use the appropriate dial for the job. MichaelG. |
Chris Trice | 12/12/2014 16:55:31 |
![]() 1376 forum posts 10 photos | 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 Haine | 12/12/2014 21:06:49 |
5563 forum posts 322 photos | 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 Wyatt | 13/12/2014 15:39:12 |
![]() 19226 forum posts 749 photos 86 articles | > 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 |
Andrew Johnston | 13/12/2014 15:50:57 |
![]() 7061 forum posts 719 photos | 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 |
AndyP | 13/12/2014 15:59:24 |
189 forum posts 30 photos | 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 Olsen | 14/12/2014 21:17:12 |
1294 forum posts 108 photos 1 articles | 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 | 14/12/2014 23:09:53 |
![]() 5068 forum posts 3 photos | 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 Trice | 14/12/2014 23:56:06 |
![]() 1376 forum posts 10 photos | 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 | 15/12/2014 00:10:22 |
![]() 5068 forum posts 3 photos | 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 Trice | 15/12/2014 00:45:01 |
![]() 1376 forum posts 10 photos | 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 | 15/12/2014 01:27:47 |
![]() 5068 forum posts 3 photos | 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 2 | 15/12/2014 05:31:52 |
344 forum posts | 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 Trice | 15/12/2014 11:23:43 |
![]() 1376 forum posts 10 photos | 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. |
Bazyle | 15/12/2014 13:52:25 |
![]() 6956 forum posts 229 photos | 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. 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 Wyatt | 15/12/2014 14:12:19 |
![]() 19226 forum posts 749 photos 86 articles | > 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 Wheeler | 15/12/2014 16:15:55 |
1227 forum posts 101 photos | 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? |
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