Cheap DRO - worth the money or just a toy?

[Beanwood]

I have to make some accurately placed holes using the mill. Normally I work to 'wood botherer' standard of accuracy - but these will need to be quite a bit better than that, as they are to hold punch and die set into a Danly jig.

My tiny Dore-Westbury mill is probably adequate for my needs, but to get this accuracy with my skills, would really benefit from a 2 axis DRO.
As there appear to be little available in a small enough size, at reasonable cost, (This machine is tiny compared to a Bridgeport, with very little room for mounting..) I have come across these:
Ebay link
It 'must' be accurate as it says so in the ad, but are they really ? I'd be annoyed to spend £60, spend hours fitting it, and find out it's not to within the stated .01mm. Has anyone tried them?

Of course if someone has small mill with DRO already fitted for £600, somewhere near Bristol, that would save some challenges...

 

[iNf]

That's £70 for the 2 scales without all the benefits of a proper dro display and options. I would look for a proper glass scales dro on aliexpress/ temu etc.

 

[m_c]

They'll likely be pretty accurate, but as @iNf says, I'd spend the extra for a proper DRO and enclosed optical scales. There are some pretty small scales available, and they aren't that much more expensive than the more common sizes.
I no longer have a manual mill, but a proper DRO makes life so much easier.

For a cheaper option, there are readers that use standard digital verniers, which give the functionality of a DRO via various options (basic displays, or a tablet), but I've not looked at them for quite some time, so not sure what the current options are.

 

[Misterg]

not to within the stated .01mm

Resolution is 0.01mm, but accuracy is stated as ±0.06mm for the 150mm scale (and I think ±0.1mm for the 300mm scale).

 

[hotponyshoes]

What travel have you got on the axis?
I think I've got a decent dro and a couple of small scales somewhere..

 

[Tinbasherdan]

What travel have you got on the axis?
I think I've got a decent dro and a couple of small scales somewhere..

I might be interested if op isn’t!

 

[RichardM]

Magnetic readers and scales take less physical space than glass. Look on AliExpress.

Conductive scales suffer with oil and cutting fluid contamination giving erratic readings in my experience.

 

[Beanwood]

What travel have you got on the axis?
I think I've got a decent dro and a couple of small scales somewhere..

I'm interested thank you

If you have 2 axis - somewhere in the region of Y at 120 - 150mm and X of 270 - 300 - it's fairly small.

If you have 3 axis, haven't measured quill travel yet but likely around 170mm.

 

[iNf]

Most glass and presumably magnetic scales can be cut down to length.

 

[Beanwood]

Right then - Just finished watching Blondihacks explain how to use them and another set of @doubleboost videos on how to intall these marvels - I can't believe I've lasted so long without one - now I just need to get on with deciding on 2 or 3 axis, buying one and fitting it.

 

[m_c]

Even if you don't fit a z dro, I'd still buy a 3 axis, as it leaves the option to fit one later for just the scale cost.

 

[skotl]

I have a 3 axis DRO with glass scales that I got off aliexpress around seven years ago for about £130 all in. Only got round to fitting the third axis a few weeks ago - video below.

But to answer the original questions:
1. Is it accurate? Yes, and repeatable - moving back and forth on any axis lands me back with a couple hundredths of a centimetre.
2. Is it useful on a small mill? Yes - absolutely - both for wood and metal bothering it makes the mill (and if you use it as a pillar drill) way faster to set up and get accurate hole patterns.

 

[Beanwood]

I have a 3 axis DRO with glass scales that I got off aliexpress around seven years ago for about £130 all in. Only got round to fitting the third axis a few weeks ago - video below.

But to answer the original questions:
1. Is it accurate? Yes, and repeatable - moving back and forth on any axis lands me back with a couple hundredths of a centimetre.
2. Is it useful on a small mill? Yes - absolutely - both for wood and metal bothering it makes the mill (and if you use it as a pillar drill) way faster to set up and get accurate hole patterns.

That’s a really neat solution and does lean me towards a 3 axis after all. I was struggling with how it would mount but you have solved it nicely.

 

[skotl]

That’s a really neat solution and does lean me towards a 3 axis after all. I was struggling with how it would mount but you have solved it nicely.

Yeah - I was really surprised, but pleased at how rigid it ended up being. It was supposed to be an R&D 3D print before remaking it in steel or aly, but really no reason now - I'll stick with the plastic setup.

 

[Beanwood]

Yeah - I was really surprised, but pleased at how rigid it ended up being. It was supposed to be an R&D 3D print before remaking it in steel or aly, but really no reason now - I'll stick with the plastic setup.

I know where to come for a set of STL files now

 

[northwest]

I went with the magnetic scales option purely because of size and accessibility and bit the bullet with the cost, bought from machine dro here.
I am, on reflection, very pleased I did and they have been excellent.

 

[skotl]

I went with the magnetic scales option purely because of size and accessibility and bit the bullet with the cost, bought from machine dro here.
I am, on reflection, very pleased I did and they have been excellent.

Oof - they look quite spendy. Is there really that much of a difference compared to the generic cheapie ones (that certainly seem very accurate and, in my case, have survived being sprayed by coolant and oil).

 

[RichardM]

My cheapies from AliExpress are doing fine as are my more expensive ones via this country.
M Dro you get the support profile, although I cannot see any wipers on the read head.
For my lathe fitment I made my own supports and covers plus some tapes are stuck direct to the lathe surfaces to save space.
Hardware wise one cheapie uses ttl signal and expensive uses RS422. No difference practically as the leads are not long enough in either application.