A really stupid question about divisions on hand wheels.

[Ken WeeksParticipant @kenweeks58536]

I have fitted DROs to the Imperial lead screw ans cross slide on my Super 7.

My 72 year old brain has got totally confused when trying to calibrate them what with mm, 1/1000", radius etc.

my question is what should the display show for

One full turn of cross slide wheel?

One full turn of the lead screw hand wheel?

I hate getting old!

Ken

[Ken WeeksParticipant @kenweeks58536]

[Tony Pratt 1Participant @tonypratt1]

Ken,

The lead screw is 8 TPI so one full turn equals .125". The cross slide is 10 TPI so one full turn is .100", I'm hoping no one will disagree?

Tony

[Ian PParticipant @ianp]

With a DRO installed on the lathe there is really no need to think about the leadscrews, handwheels, or graduations. It matters little how far the slide moves in one handwheel turn because the actual distance it has moved is displayed in plain English directly on the display.

Yes, you have to decide whether to show the cross slide movement as a radius or diameter but you can usually switch between imperial and metric units instantly and you can also set zero at any point. As far as I know, non of the commonly available DRO systems need 'calibrating' and their magnetic/glass or whatever scales are not adjustable anyway.

Ian P

[KWILParticipant @kwil]

Ian is correct in pointing out that in respect of the cross slide, you really must know whether the DRO is set up to diameter or radius, Fortunately the answer is quite eady to spot since a step change in radius = 2 steps in diameter.

As regards "calibration", non linearity of the scale is correctable on some systems, particularly industrial ones.

[Ken WeeksParticipant @kenweeks58536]

I am using the B and W Electronics wire scales they say on setting up to move the the slides by a known amount to ensure they are reading correctly and adjusting the read out display if required.

[Ady1Participant @ady1]

Don't look at your handwheels anymore, look at the DRO readout

If you want to check its accuracy use a DTI

Edited By Ady1 on 31/05/2017 15:23:00

[JasonBModerator @jasonb]

Posted by Ken Weeks on 31/05/2017 14:22:54:

I am using the B and W Electronics wire scales they say on setting up to move the the slides by a known amount to ensure they are reading correctly and adjusting the read out display if required.

Stick a DTI against the carrage and check against that to make sure you are getting like for like movement without any backlash which you may get if comparing with the handwheel. Long travel plunger type is probably best.

[Sam Longley 1Participant @samlongley1]

Posted by Ken Weeks on 31/05/2017 11:47:07:

I hate getting old!

Ken

You would hate dying young a lot more

[Ken WeeksParticipant @kenweeks58536]

Very true Sam

[mechman48Participant @mechman48]

I have fitted DRO's to my WM16 mill; I have not bothered with graduations since, I just look at what the DRO's show, no need to worry about backlash either, the readout wont change until the table moves in the X or Y axis, not had any probs since, as the song goes 'don't worry, be happy'… & I'm 69

George.

[vintagengineerParticipant @vintagengineer]

There are never stupid questions just stupid answers.

[John ReeseParticipant @johnreese12848]

A few months ago I installed a DRO Pros unit on my South Bend 10K. That unit also has settings for scale resolution and display resolution. I had to find the right combination of those settings to get it to read correctly.

If it makes any difference I am 79.

I did find that with the lathe off I get stable readings on both axes. With the spindle turning the X axis display is not stable in the last digit. I suspect vibration in the scale or read head mounting is the cause. I usually work in imperial units and I have the readout resolution to 0.0001".

The fact that I can read the actual cross feed position to tenths allows me to achieve accuracy that formerly I could only dream about.

[Ken WeeksParticipant @kenweeks58536]

Thanks everybody for the replies..

I have said before this site never fails to amaze with the amount of information and support freely given.

I have always worked with no question is stupid if you do not know the answer better to ask no matter how stupid it sounds than to dig yourself in.

[Ian S CParticipant @iansc]

When I was nursing, we had a sign in the ward office, "It's better to ask dumb questions than make dumb mistakes".

Ian S C

[Ken WeeksParticipant @kenweeks58536]

I have know got it working just need to use it and get used to it.

Thanks everybody for your input.

Ken

[RRMBKParticipant @rrmbk]

Hi Ken. I fitted DRO to both Mill and Lathe last year. It does take a leap of faith to trust them after years of using handwheels and backing off and returning to take backlash into account. However once you do and you gain trust in them they are great.

I recently produced a batch of 20x 2 BA fitted bolts 1.5 " long shank. with 1/4 thread on the end that had to be accurate in the length of plain shank and thread . It is just so easy to set to zero on the end of the stock and run the length down accurately to a stop measurement. and each one comes out the same. As a tip, I personally find it easier to get the length right on the first pass and then reset that end point and work all subsequent passes towards zero.

When it comes to reducing diameter, that becomes even easier, except as people have mentioned you must be clear if your DRO is measuring in Radius or Diameter. once you know how much you need to remove, just read it directly from the DRO, no need to wind back and wind in again to eliminate backlash.

Practice on some scrap to build your faith in them and once you do trust them , believe me you will never want to go back !

Enjoy.

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