DRO On Lathe

[EdK]

Anyone that has a DRO on your lathe can you tell me if you have this feature?

I've drilled a thru-hole in the piece and then bored it just enough to get a good finish. I've measured the hole with an inside micrometer and now I want to bore it to size. I can set the lathe axis to the starting diameter but when I go to bore it to size the display reads a smaller number as I increase the hole size. I could do the arithmetic but it seems like there should be a function in the DRO to do this. Maybe there is and I'm just not understanding the nomenclature in the manual. So does anyone know if their DRO can do what I'm trying to do, display the size of the bored hole properly as it's enlarged?

Ed

[PixMan]

Great question, Ed.

My DRO is definitely "old school" and almost useless for this other than that I can zero it out anywhere and switch from + to - direction anywhere. If yours has a full numeric keyboard and a switch for +/-, you could take a light cut, retract tool without moving, measure the diameter and enter it into the DRO with the correct +/- setting so the display gets a bigger value as you make the bore larger.

[f350ca]

Are you cutting on the back side of the bore with the tool upside down Ed? If so you need to enter the dia as a negative number.

[EdK]

(01-27-2015, 12:17 PM)f350ca Wrote: Are you cutting on the back side of the bore with the tool upside down Ed? If so you need to enter the dia as a negative number.

Greg,

No, I'm boring as usual. I believe the DRO is displaying the point along the cross slide lead screw and since, when boring, you're usually bringing the cross slide towards you it's displaying that position rather than the diameter of the bored hole. I'm thinking it would have to be a special function built into the DRO to accomplish but what the hell do I know.  

I sent an email to the DRO company and their tech guy isn't in today so I'm going to give him a call tomorrow. I'll just continue on with my project by measuring and getting close and measure some more until I hit the dimension I need. But I sure would like to be able to use more than just the basic features of the DRO like I'm doing now.

Ed

[PixMan]

What make and model DRO unit do you have, Ed?

[EdK]

I got a response from the tech guy and he said my cross slide scale should count positive as I move it towards me, which makes sense. They have a PDF file available on how to change it so it's reading properly. Now I'm wondering if my scales have always read in the wrong directions. I'd never know since this is my first lathe with a DRO. So you guys with DROs on your lathe, does the count go down when you bring the carriage towards the head stock and does your count go down when you move the cross slide towards the rear of the lathe?

Currently the count goes down as I move the carriage towards the head stock but the count goes up as I move the cross slide towards the rear of the lathe. My cross slide seems to be wrong.  

Ed

[EdK]

(01-27-2015, 12:40 PM)PixMan Wrote: What make and model DRO unit do you have, Ed?

Ken,

I've got this one a DRO PROS Electronica EL400 Digital Readout kit.

http://www.dropros.com/DRO_PROS_Lathe_Di...adouts.htm


Ed

[f350ca]

Ed, if the count goes up as you move the cross slide to the back, (ie as the dia gets smaller, then the scale needs to be reversed, electronically in the readout. The manual should tell you how. If thus is the case it must not work for OD turning either, OD ID is the same. A quick fix is enter your measured dia as a negative number.

[EdK]

(01-27-2015, 02:20 PM)f350ca Wrote: Ed, if the count goes up as you move the cross slide to the back, (ie as the dia gets smaller, then the scale needs to be reversed, electronically in the readout. The manual should tell you how. If thus is the case it must not work for OD turning either, OD ID is the same. A quick fix is enter your measured dia as a negative number.

Greg,

I can change the direction of the count to fix the cross slide. What I'm still wondering is what should the count do for the carriage when moved towards the head stock? I'm assuming it should decrease but I'm not sure.

Ed

[stevec]

Ed, If you didn't have the DRO you'd have to read the dial backwards wouldn't you.
I always use the locking feature on my dial and just before taking the final cut I set it to zero and back it up half the distance  remaining  to be removed.

My 16 x 60 has a DRO and I use it because the dials are in MM.
I just zero it and advance the cross feed by the same amount as above.

Am I missing something?

Steve