Dros without breaking the bank?

I was thinking of fitting my mill with a DRO setup. In an idle moment, I started looking at commercial items. It looks as though going by those prices , the DRO setup will set me back more than the mill cost!

I don't mind a good bit of soldering and board interfacing. So is there a cheaper method than buying ready brewed items? I would want repeatability of positioning to at least a "thou", otherwise I may as well stick to the old manual methods!

Is there any info on the net that might be of help? I did try looking but there seemed to be a huge amount of information there, little of it relevant to my needs.

Try http://www.yuriystoys.com/2012/09/do-it-yourself-dro-with-arduino-and.html

John Haine got in first with Yuriy's Toys which is the closet match to your requirement I know of. But more to it than ' a good bit of soldering and board interfacing' as it involves a programming an Arduino and a Tablet Computer. By the time you've paid for the scales, the computers, power supplies, boxing it up for use in a workshop, and your time it's not exceptionally cheap.

Despite being interested in programming I chickened out and bought a pair of units like this from Warco for less than £100, ArcEuroTrade sell them too. It's their image.

Obviously these aren't as clever or robust as the more expensive units. In particular you have to keep the scales clean and the batteries charged. They are only accurate to ±0.02mm (rather better than 1 thou) However, I've been using mine with only minor glitches for over two years. The glitches were due to: flat batteries, dirty scales, misaligned scale due to a loose screw. They are as accurate as my dials and - most important - you don't have to worry about backlash.

When I bought them I wasn't completely convinced about DROs. Silly me - even a basic DRO transforms a milling machine. I'm completely sold now; if either of my cheaper DRO units fail I will cheerfully put a more expensive unit on the mill. A centralised display and controls, better accuracy, and coolant proof scales are all worth having.

Dave

+1 for the above, I've had my mill fitted with a set of these & so far the only glitch has been flat batteries, had them on getting on for 3 yrs now, so much easier & definitely more accurate.

George.

Two axis proper DRO on ebay from China at £188. Before I got hold of a second hand readout display for my Bridgeport I nearly ordered one. Pricey but a proper job.

If you do fit the cheap capacitative scales but worry about reliability, the read heads are relatively inexpensive, these ones from Machine DRO can be used to 'refresh' both scales and cheap calipers:

Though requiring some delicate soldering, I got around the button cell depletion problem by wiring each of the 3 heads back to a little "Maplin box" containing a single Mallory battery. Dubious about voltage difference, but everything has worked OK for years. Saved quite some money on the button cells which always seemed to deplete in no time.

Thanks for the information gentlemen. I have had my bellyful of programming over the years and I don't want to learn any more at my age! The last programming bout was to programme PICs and in the end it turned out to be more trouble than it was worth for my application.

The Arc Eurotrade units are more in my price line, but batteries don't seem to last in my workshop, even good quality ones. I am also a bit troubled with the scales being so finicky in terms of dirt and protection. I may well give them a try, but the readouts look small and I would prefer a bigger and brighter display, but then you can't have that at the price! I suppose that they would be a good trial to see if I like the DRO system sufficiently to invest in more bomb proof mains powered kit!

Thanks again,

Andrew.

I started off a number of years ago with a self build Shumatech-350 DRO and used it for a few years, but it was never that great. The display was not that stable and there were other niggles with it. I then replaced it with a glass and magnetic scale set up from Machine DRO and the difference was stark. Rock solid stable and always repeatable and a joy to use.

​ I understand that there are new Shumatech DRO kits which may well be much better than the one I had, but they still involve a lot of work to build them and I would not go down that route again myself. In my experience the glass or magnetic scales are much better and more reliable than the alternative Chinese capacitance type scales.

Doug

Les Jones has a schematic on his website, part of which uses a voltage regulator to power the scales....maybe worth looking at if battery life is an issue.....

http://myweb.tiscali.co.uk/leshobbies/leshobbies/Android%20DRO%20interface%20files/Scale%20Interface.pdf

Les, hope you dont mind ne sharing....

That's a good idea! Although the button cells on my DRO scales last about a year they fail at the most inconvenient times. Four times now I've been in the middle of a complicated job only to have to stop, replace the batteries, and recover reference zero on a scale before being able to continue.

Look at Machine DRO there offerings work fine on my Sieg 3, Somewhere about £300 for all 3 axis.

...but batteries don't seem to last in my workshop, even good quality ones. I am also a bit troubled with the scales being so finicky in terms of dirt and protection. I may well give them a try, but the readouts look small and I would prefer a bigger and brighter display,

These are my displays as set up, I find them clear enough to read, for me,



I have also fitted aluminium angle over the 'X' axis for protection & a piece of clear vinyl over the 'Y' axis for splash protection, ( haven't got pic ) ...



George.

Fantastic link Neil, Thanks!
I started off with LCD capacitative and I have several that failed after a few years but couldn't bring myself to throw away in case they could be repaired

I'm used to big LED DRO displays now but I have some metrology projects that I could use the repaired LCD scales for,

Regards,
Nick

I'm not sure I could be bothered to wait until 27 June 2016 before they have stock though, even with a 5% pre-order discount

Brian

Andrew,

If you prefer a larger display then I use this remote display from ARC combined with this type of read-out bar and reader. This combination also does away with batteries as the Remote Display Unit is mains powered through a transformer.

I have found this combination a relatively cheap, and for my purposes, accurate system. My only reservation is that the tiny and somewhat sensitive connecting plugs at the 'reader' end need looking after and occasional cleaning. I use a contact-cleaning spray to do so. (Don't want to derail the thread.... but ....any suggestions to overcome this issue most welcome).

Other suppliers available of course, but I found ARC very good.

Regards,

Phil

By going that route Phil your exceeding £190 3 axis straight away and limited to one scale at sub 400mm long.
Going back 18 years think i had a 24" cut down on a 14 1/2" travel, have to allow several inches extra for read head and of course dearer than 400 long, cost me back then £226 and about £100 in batteries over 2 yrs.
Replaced read head four times in two years no matter how much you try and contain the units, angle and channel wont do it. Not to mention alkaline batteries bought by the dozen lasted anything between 2 and 6 weeks. False economy even over 12 months when a proper setup will sting you just around £230 region.

Andrew if do go the scale type i have a 3 axis Warco cost £150 on discount but needs one new lead, yours for postage to get rid of it. ARC equivalent £102.

I have both Warco and Arc. Warco is two axis and the Arc is three.

I'm not sure that the measuring specs are quite as reported above, so one needs to read the specs carefully.

What I do know is that the Warco is battery only and the Arc is also mains powered (but may need batteries in the readers).

The Warco display is rock solid, but the Arc zero tends to wander. Not sure if it is just my example, or not. It was good enough for what I wanted at the time. I have a full 3 axis dro, with all the bells and whisles, on my Centec, anyway.

I would fit the 'bells and whistles' type, if it were mine, as it would appear (by previous report) to be in close-to-new condition.

It is a very quick operation to remove and replace the button cells on the cheap DRO if it is not to be in use for a while. I have used mine for about 8 years and had two failures which I repaired by dismantling the reader and VERY THOROUGH cleaning of the circuit boards and metal parts.They both worked properly on reassembly. Removing the button cell when not in use gives you a chance to avoid the corrosion which can be caused by a dead cell . As Neil has pointed out replacement readers are not expensive anyway. It is necessary to keep the reader clean and I try to achieve this by tucking a piece of stiff folded paper in the form of an angle over mine. Colin

I try to achieve this by tucking a piece of stiff folded paper in the form of an angle over mine

Mine have metal covers over the full length. They were sealed, against coolant ingress, with a silicone sealant. Paper is not much good if flooded coolant is anticipated. I've not yet sealed mine but do expect to use coolant when I get it in its ginal position....