DRO Question

Hi everyone, hope you are all well. I recently bought a used Chester bench top mill and I’m really pleased with it. One of the attractive parts other than the price was the fact that it had been fitted with a DRO - nice little blue thing, inexpensive but works well. I have been persuaded to purchase a larger head unit, one that’ll do various calculations, bolt rings, trigonometric calcs etc etc. But, when purchased over the internet, no mention of scale types was made. My machine has the magnetic type and I hope that it is compatible with the new head. Does anyone have any experience of swapping types on their setup? Further, there will have to be some minor butchery in the workshop as the cable that comes out of the magnetic reader terminates in an RJ-11 plug, whereas the new head requires the DB-9 interface - there is therefore an obvious question about pin outs. Again, has anybody had experience of doing this particular piece of surgery? If my eyes weren’t fading I’d leave well alone - the magnetic scales have been fitted so well by the previous owner (alas a silent key) that I am loathe to change them if I can avoid it. So any help, at all, will be gratefully received. Aye, Peter.

Edited By Peter Sullivan 1 on 28/05/2021 17:06:25

Hi Peter,

I use pad and pencil with my calculator so I can always refer to it. Never used the fancy functions on the DRO system.

Yes, they do work well enough. Indication to 0.01mm, but obviously less accuracy/precision when standard errors are included. With mine (the three axis version) readings are not quite consistent in that last decimal place, either. But good enough for what I do. Purchased from Arceuro.

I was considering using the scales and change to a large ‘calculating’ read-out. Enquiries to both the suppliers of those units and possible read-out heads were not helpful, so I simply decided to run the calculations (pitch circle holes for example) on my other set-up and just use the coordinates, calculated, on my little mill.

This thread may help me proceed further, but I’m not into such intricacies unless found really necessary. M-dro could supply conversion connectors but one is on one’s own until you know what you need!

You need to compare the input specs on the new and old display, they should be listed in the manuals of each display.

Hi Dave - I have the pinout for the new one out of the book that came with it. The problem is the older, existing, head - it came with no paperwork at all and hunting it down on t’internet has proved fruitless.

Those scales don't look like the magnetic type, if they are similar to a vernier caliper they probably are capacitive scales.

Edited By ChrisB on 28/05/2021 19:34:04

Chris - ah well, there you go you see. I’ve only presumed they’re magnetic type - I have seen the exact same scales on vernier callipers but if you say they’re capacitative type then I can maybe go from there. Would they not be compatible with my new DRO head then would you say?

Peter

The current DRO setup you have looks like the ones sold by Arceuro. I am pretty sure they are capacitive type, the same as digital calipers. In fact they look like digital calipers but fitted with an output socket.

Unfortunately, they won’t be compatible with your new display unit which is designed for magnetic or optical scales which have a different output format.

I think you have 2 options : buy new scales or return the new display unit if possible and buy or make an interface to use your existing scales with the TouchDRO app using an android tablet as the display. I have this system on my mini lathe and on my mill. They both use diy interface circuits I made myself. I have used modified Lidl digital calipers on the mini lathe and Arceuro scales on my mill (though they are different to the ones you have).

Here is the link to the TouchDRO developers site: **LINK**

Stuart

Or I suppose a 3rd option : use them as they are.

Edited By Stuart Smith 5 on 28/05/2021 20:09:28

I agree with chrisB that your scales are the capacitive type and they will not work most display units as most of them expect quadrature signals which most glass(Optical) and magnetic scales provide. To make things more complicated there are a number of different protocols used with capacitive scales. There is one DIY design that works with some types of capacitive scales. This is a link to it.

**LINK**

I have not followed that project for a few years so I don't know the capabilities of the current version.

Les.

Les, Chris and Stuart - thank you for your excellent input. As Captain Darling would say - Oh Bugger. I think I’m going to have to get me a pair of magnetic scales and fit them after all. It leaves me with a perfectly serviceable, albeit second hand, Arceuro system. I may try to adapt it to fit my ‘35 Drummond M lathe, but I’m having difficulty in imagining the value of that - it may end up on eBay. Thanks once again for your help, it is much appreciated. Peter.

They are useful if one wishes to use the lathe in ‘the other units’ to what it was manufactured for.