The mill probably comes with a dro on the quill, in which case a 2-axis dro is all that's needed. But it's convenient to have all three displays in the same place if money is no object. Being a cheapskate I've not bothered!

Dave

I suppose a lot depends on how much the height of what you are working on varies and whether you might need to raise the head yo change tooling. Also whether you want the loss of rigidity as the quill is extended. There are also a few functions on a DRO that won't work with just two axis but they are unlikely to be used that much.

Myself I started with a 3-axis display and just scales on X&Y but soon added the Z scale and would not want to go back.

You can certainly get away with only two, but I'd go for all three if I had my time over again.

I bought my Warco WM18 with a 2 axis (saving about £180 over the 3-axis) but I felt the need for a Z axis DRO at a later date, for most of the reasons mentioned by Jason.

This meant I faced a choice between buying an additional glass scale and a new display [rendering the 2-axis display redundant] at a cost of nearly £300 or just buying a standalone DRO with remote display for around £50.

I chose the latter, but the labour involved in upending the garage to fit the Z axis scale meant I really should have just gone for the 3 axis originally.

There is, however, one slight advantage in choosing the type of DRO I've got on my Z axis: it holds an absolute reading even when powered off, unlike the DRO supplied with the mill.This can be an advantage if you move the head when everything is powered off but want to get back to a previous position infallibly.

Edited By Bill Phinn on 25/02/2021 20:33:34

I started with a 2 axis console and X and Y scales on my Warco VMC. I did miss the ability to set depth. When the console failed I replaced it with a 3 axis unit. Eventually i fitted the z scale on the knee. This made a lot of difference. Ideally I I would like to put a scale on the quill with a summing unit to complete the setup.

I also started with a 3 axis display on the mill but only scales on the X and Y, but soon added the Z when the opportuntity arose, and wouldn't be without it.

I believe at one time Warco said one couldn't fit a scale on their round column mills, but I managed to fit one on mine – where there's a will there's a way!!

CHris

+1 for Duncans advice to go for three axes on the x-y-z slide ways to use in conjunction with the separate quiil readout.

That's what I have on my Bridgeport. 3 glass scales on X-y-z and a BW Electronics pull wire sensor on the quiil. It's great.

Do verify that the DRO box stores its last position on power down and that it has a decent supply of offset memory positions. Mine stores up to 99 which is a bit excessive but creative use of the positon storage can save a lot of head scratching and potential errors during set up and machining. My no 1 memory is permanently set to zero at the mid traverse positions. I'd have saved a metric boatload of effort over the 15 or so years I've had my Sino DRO box if I'd made a serious effort to explore the ways in which the position storage could be used to make life easier.

Clive

Edited By Clive Foster on 25/02/2021 22:45:32

I would say that you will never regret getting it but you may regret not getting it

Had a Warco WM16 mll for a while with X and Y DRO fitted. Never really found any problems with Z axis settings as there is a basic quill DRO factory fitted. I assume any DRO fitted will not be on the fine feed of the mill if it is a WM14/16 etc. I have rigged up a DTI a few times where I needed to ensure accuracy but found the quill DRO was as good. I suppose the answer is – if you can afford it you may as well have the extra DRO on the Z axis. It is probably fitted to the headstock so settings will be from the Z axis hand wheel and not the fine feed on the quill.

Maybe Herbert can answer how he gets on with the Z axis DRO.

From my limited experience with a Chester 626 definitely 3 axis with 4 scales – X,Y and quill and table combined through a summing interface for Z.

William.

I have a Chester 16V and I was not really convinced about DROs. Anyway, in a moment of madness, I bought a M-DRO magnetic kit for X, Y & Z axes and it is impressive – I've seen the light, I'm converted.

I also have a cheap DRO available (not sure where I bought it) and I will be fitting it to the quill.

Phil H