Both, but the each mark is off by .0002 in imperial because of the lead screw pitch. I’m a software engineer for a Japanese company so I’m well versed in metric measurements, but my assumption is most of the tooling I can get here will be imperial and it is what I can visualize more easily. I’ve considered just going to all metric and be done with it though. Lol
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Radius/diameter turning mode
- Thread starter Scorn64
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- Sep 24, 2020
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you will never notice the 2% variance, and the dials are marked with 40 increments which is 1 mm per rev.
- Joined
- Jul 17, 2020
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Yeah, my lathe also has metric lead screws and inch dials, and I never even notice. On a 7x16 lathe, you won't be taking cuts anywhere near deep enough to lose track of your position, nor will you be taking cuts precise enough for two tenths to matter at all.
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- Feb 27, 2014
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I see that a number of people suggest that you do not use the DRO initially until you have practice using the handwheels. I respectfully disagree with them. My lathe did not come with a DRO and so I did use the hand wheels first. However the DRO is such a game changer on the lathe for a part time user that I would never consider a lathe without one. Perhaps if you plan to have multiple lathes or make a profession out out of lathework learning the handwheels first is a good idea, but if you are like me and this is a part time hobby, Use the DRO from the start and don't look back. BTW, I use Diameter mode almost all the time. This matches my drawings and my thinking but has gotten me into trouble a couple of times. 
I’m nearing retirement, so I’m not looking to do anything except enjoy the experience. In my job I automate large mining equipment so I’m very use to a digitized experience. I don’t want CNC (that’s too close to just being my work) but I’ll use the DRO. More than the discussion here I like that it ignores the slop in the carriage and makes rounding errors from measurement systems much smaller. With that said I understand you have to know the physical equipment (limits, quirks) in order to be able to use it effectively/safely. The main thing for me was; is it a mistake to deal with diameter instead radius. It seems most like dealing with diameter. I don’t have my lathe yet, but I think it’s dials are radius.
I hadn’t thought about needing to turn diameter mode off on a non diameter. Hopefully I can apply diameter mode to a single axis and not others in TouchDRO. I would think so if it’s use on lathes much. Needing to remember to turn it off would probably make me not want to use the mode.
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- Mar 26, 2018
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- 2,724
You should be able to apply it axis by axis. You set it up once and leave it there.
- Joined
- Jul 17, 2020
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- 323
I'd bet your lathe will come with diameter dials. Really it doesn't matter, as long as you get used to it.
That the DRO ignores backlash is definitely something you need to keep in mind. There is no way you'll ever get rid of the backlash in the leadscrews, not being high quality ballscrews or anything. If you back off the cross slide, the DRO won't show you the backlash unlike the dial, so you need to remember to turn the dial the right way before taking a cut.
That the DRO ignores backlash is definitely something you need to keep in mind. There is no way you'll ever get rid of the backlash in the leadscrews, not being high quality ballscrews or anything. If you back off the cross slide, the DRO won't show you the backlash unlike the dial, so you need to remember to turn the dial the right way before taking a cut.
The old Sherline that I’m coming from doesn’t allow you to zero out the dial. It can be a pain moving in and out and dealing with backlash and where you need to be. I’m looking forward to being able to see fairly exact values based on actual movement.