An argument for indicators & gages in lieu of a DRO system for work positioning

[SouthernChap]

It uses a rack and pinion as the scale mechanism.

Oh, right. Yeah, that's not going to help.

That and the reply from @PNW_Guy has reassured me, as a reasonable quality set of Chinese glass scales, a cheapish tablet and a TouchDRO adapter isn't that expensive.

Perhaps you could give the above a shot and see if such a decent DRO solution might change your mind about DROs.

 

[RJSakowski]

Can anybody tell me if this is this a common level of error in DROs?

As a beginner in machining, this is not what I was expecting. I mean a few tenths I'd not be surprised about but a couple of thou, regularly?

That seems like it would make the DRO 'chocolate teapot' useless. One would be better off, as the OP says, relying on the machine dials, clocks and gage blocks/pins.

The actual calibration certs that came with my Grizzly DRO (essentially the same as an Easson DRO) show the actual maximum error less than 5 microns.

DRO scales don't necessarily come calibrated. There usually is a calibration procedure in the back of the manual to correct any inaccuracy. It is best to set that up for the greatest distance that can be accurately verified by alternative means. I used my1" x 6" parallel along with my 5-6" micrometer for that task. I clamped a couple of 1-2-3 blocks at right angles to my table after sweeping them with my dial test indicator to ensure they were parallel to travel. Then I zeroed the test indicator on the first block and set the the DRO at zero. Next in moved the table to permit inserting the parallel and and moved the table to zero the indicator on the parallel. My parallel happened to measure out to slightly more than 6" but I compared my DRO reading to the measured parallel length and followed the instructions in the DRO manual to correct the reading so it matched the parallel length.

Depending upon the scale length, the length of your calibration standard, and the resolution of your measurement instrument, You could very well see some measurement error when the maximum travel is used. That is why you want your standard to be as long as practical. I am fairly confident that my calibration over 6" is good to my ability to read the length of my parallel, so probably +/- .0001". My maximum x travel is 18" so an extrapolated error due to calibration would be about +/- .0003" or 7.5 microns. Add to that the display resolution of 5 microns and I am looking at something on the order of .0005".

 

[sdelivery]

EXACTLY

The actual calibration certs that came with my Grizzly DRO (essentially the same as an Easson DRO) show the actual maximum error less than 5 microns.

DRO scales don't necessarily come calibrated. There usually is a calibration procedure in the back of the manual to correct any inaccuracy. It is best to set that up for the greatest distance that can be accurately verified by alternative means. I used my1" x 6" parallel along with my 5-6" micrometer for that task. I clamped a couple of 1-2-3 blocks at right angles to my table after sweeping them with my dial test indicator to ensure they were parallel to travel. Then I zeroed the test indicator on the first block and set the the DRO at zero. Next in moved the table to permit inserting the parallel and and moved the table to zero the indicator on the parallel. My parallel happened to measure out to slightly more than 6" but I compared my DRO reading to the measured parallel length and followed the instructions in the DRO manual to correct the reading so it matched the parallel length.

Depending upon the scale length, the length of your calibration standard, and the resolution of your measurement instrument, You could very well see some measurement error when the maximum travel is used. That is why you want your standard to be as long as practical. I am fairly confident that my calibration over 6" is good to my ability to read the length of my parallel, so probably +/- .0001". My maximum x travel is 18" so an extrapolated error due to calibration would be about +/- .0003" or 7.5 microns. Add to that the display resolution of 5 microns and I am looking at something on the order of .0005".

 

[mac1911]

A few months ago i brought home a bridgeport mill and Monarch 10EE lathe both of which were equipped with CBX DRO systems (3 axis on the mill, 2 axis on the lathe). I've never used a DRO system before and had grown acustomed to using a combination of machine dials, gage blocks, planer gages, micrometers and dial indicators for work positioning. While at first look, the DRO system promised to reduce/eliminate the need for these methods. However, I found that in order to compensate for cumulative error (.001 or ,002) inherent in the DRO system, I was checking dimensions using my old methods. In conjunction with this, I grew tired of working around the transducer wires and the scales when cleaning the machines. I finally made the decision to remove the DRO systems all together and revert to my old ways. I have not regretted this decision. Has anyone else made this decision and if so, what was your reasoning?

Ok being a complete non machinist and on a somewhat negative budget I have little choice that to use the indicators I have on hand.
They work and have helped me greatly BUT man they can be a pain. Bump them and its all done!
Having used a lathe with a dro
I much rather have the dro.
Thats all I have
How well I can utilize my tools is probably a bigger error than anything. Lol

 

[verbotenwhisky]

Ok being a complete non machinist and on a somewhat negative budget I have little choice that to use the indicators I have on hand.
They work and have helped me greatly BUT man they can be a pain. Bump them and its all done!
Having used a lathe with a dro
I much rather have the dro.
Thats all I have
How well I can utilize my tools is probably a bigger error than anything. Lol

If you are pinched for funds and every penny counts take a look at Igage DRO's, they are not the best but I have cut many a part using them. The link I left shows an example, you can order them in lengths as required. I do not use a DRO to hit a final dimension if it is critical, I get close then switch to the more precise instruments.

 

[RJSakowski]

If you are pinched for funds and every penny counts take a look at Igage DRO's, they are not the best but I have cut many a part using them. The link I left shows an example, you can order them in lengths as required. I do not use a DRO to hit a final dimension if it is critical, I get close then switch to the more precise instruments.

I use the iGaging DRO scales on my lathe. I used it because the only scales that would fit my lathe cross slide at the time were the capacitive scales. The resolution of the capacitive scales is 10 micron or ,0004". They are used with the early TouchDRO system. I have my display set for four digits see less than one thou movements.

While the current TouchDRO system no longer supports the capacitive scales, I believe that the DIY system information is still available. https://www.touchdro.com/resources/adapters/diy/

Here is the thread on the install. https://www.hobby-machinist.com/threads/another-lathe-dro-install.34106/

 

[Dabbler]

I have a iGaging DRO kicking around. I had 3 but sold 2 of them at half my cost.

For about 100$ more (for 3 axis), an offshore DRO may well be a better deal. Even the convenience of the multi tools and radius/diameter makes an offshore DRO work a little better at a little more money.

For a budget solution on a little lathe, they do work quite well.

 

[mac1911]

If you are pinched for funds and every penny counts take a look at Igage DRO's, they are not the best but I have cut many a part using them. The link I left shows an example, you can order them in lengths as required. I do not use a DRO to hit a final dimension if it is critical, I get close then switch to the more precise instruments.

Good thing is im most likely never going to have “critical” numbers to hit lol.
But man oh man DRO would be easier faster than Indicators and chicken scratch math im always secound guessing !!!