DRO's

[Kram]

Please tell me about DRO's. Which is best on a cheap hobby budget. Ive done some lathe-milling recently and have a digital calliper on the vertical it makes everything easy, so I want the proper thing for carrage and cross slide. I have another calliper for the tailstock unless the dro will come with one.

Cheers
Mark

 

[Dr.Al]

Have a chat to the folks at Machine DRO. They're probably not as cheap as some of the direct-from-the-far-east options but they know their stuff and they have a range of products at different prices.

I've got a SINO DRO (SDS6-3V I think) on the milling machine with optical scales. I've always been wary of magnetic scales as little bits of cast iron dust or possibly steel swarf could play havoc with them. Inductive could work, although the accuracy of an optical scale will be better than inductive. Accuracy wise it's optical then inductive then magnetic. The SINO ones I've got are 5 μm resolution† optical.

Optical ones can get dirt which can obscure the view (although they'll average over a certain distance and be able to ignore dirt up to a certain size) but can be cleaned (carefully) if it ever becomes a problem. They're usually well shielded to keep dirt out. Inductive tends to be robust but less accurate. Magnetic is sensitive to swarf and less accurate again.

High end industrial machines will usually use optical absolute‡ encoders, but they cost way too much for hobby use.

I've not used a DRO on a lathe. I have a Trav-a-Dial which works for the carriage travel and a caliper mounted to the tailstock; I've never felt the need for any other axis although I'd probably get a DRO if I didn't have the Trav-a-Dial.

Disclaimer: I design electronics for high end optical position encoders for a living (but not ones that any hobbyist is likely to buy due to their price). If I were kitting out a machine with a DRO now, I'd probably see whether I could scrounge any old test units from work!

† Note that resolution is very different to accuracy. There are a lot of sources of error in a position measurement and it's not always easy to tell from a datasheet what they'll be. Just because something says 5 μm resolution, don't assume that you'll get 5 μm accuracy.

‡ Absolute as opposed to Incremental - when you turn the power on they already know where they are even if the machine has moved with the power off.

 

[R-D-R]

+1 for contacting machineDRO I used them for my lathe DRO last year. Was in between Chinese system or brand. Went with the latter and been very pleased it transformed my lathe (I’m a novice).

look carefully at how the scales work some are quite fiddly to mount and require precise installation some are more forgiving with simpler install requirements.

 

[dyno-tron]

Depending on how "DIY" you want to go you could take a look at https://www.yuriystoys.com/?m=1

It interfaces low cost scales to an android app via Bluetooth, the app is free and turns you tablet into a sophisticated touch screen DRO with all the usual functions.

I already had scales on my mill (with rubbish LCD readouts) and an old tablet so it was a cheap way to upgrade to a decent DRO. It works very well!

 

[addjunkie]

Id agree machine DrO are very helpfull. I bought from them for my last lathe. But I will say the far eastern option on the last DRO thread on here, looked awfully similar to what they sell, with a lower price.

 

[chrisg3103]

https://www.mig-welding.co.uk/forum/threads/denford-viceroy-280-vs.90489/page-2#post-1424974
At the bottom of the page is my DRO fitting experience, so far not let me down!
Bought on ebay from a uk seller, clearly got shipped from china but heyho. For £140 dont expect super quality but it works

 

[Kram]

Had a look on MachineDro, they have lathe and mill specific ones. Whats the difference? I can see milling functions like pcd coordines being useful if I put a proper one on vertical slide.

@chrisg3103 looks good, mind if I ask which one you got?

Im unsure about cross slide, unless it can be made to fit inside with the screw, else tailstocl would be too short, mine is only 60mm travel.

 

[addjunkie]

Lathe normally 2 axis, has dia/ radius function, tool offsets etc.

Mill has cordinates, arcs, 1/2 function......pcd....and more, but often has 3 axis, etc

 

[chrisg3103]

https://www.ebay.co.uk/itm/174108068558

Got my bits from this guy but holy heck! His prices seem to have shot up I only paid £57 for the display £37 for the 200mm scale and £45 for the 600mm.
The displays are much the same, JCS900-2AE is 2 axis 3AE 3 axis and has full milling functions. Non of which I needed, manual was surprisingly good

 

[Agroshield]

Had a look on MachineDro, they have lathe and mill specific ones. Whats the difference?

I think the display can be swapped between machines which could save you a bit of money. So if you are likely ever to buy a mill, buy a mill display. Even more so if you want to put a readout on the vertical slide.