Mill DRO Recommendation

What’s up YouTubers. I’m looking for a Mill DRO for our Bridgeport. My mill has little numbers on the handles that spin, but I don’t know what they’re for or how to read.

For real though, we have tooling that shares a common zero datum on our mill and it would be sick to have a DRO that remembers the location of that datum so that we can reset between operations, while allowing for a zero reference during the operation.
I don’t know if such a function exists and wasn’t able to figure it out with a quick Perusal of DRO Pros’ website.

Any of you scientists have a DRO that you love and trust? Can I have it for free? Just kidding.

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If your milling machine is imperial units (inches), then each tick on the handles should represent 1/1000 of an inch of movement of the table. There should be 100 ticks around the handle, so each full rotation of the handle = 1/10th of an inch. 10 rotations of the handle = 1 inch, etc. This is how you know how much the table moves if you don’t have a DRO.

A DRO is very nice, will save you some time, and be more accurate (backlash, etc.) but it isn’t absolutely necessary.

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Sorry Dave, I was trying to be funny. Im actually looking for a DRO rec because it’s too time consuming to use the handle scales when switching between operations. Thank you for the concise tutorial though!

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I purchased a mill from that came with a version of the TouchDRO setup:

If you install it from scratch it sounds like it might require a bit of extra DIY effort, but it runs off a tablet and has a very large feature set that makes it configurable for different workflows - I’d recommend checking out the documentation to see if it’ll do what you need. I’ve never used a “conventional” DRO so I don’t know how it compares, but it does what I need and more.

I think most modern DROs have tool library functionality that will do what you want. I don’t have any specific recommendations I’m afraid. I think a lot of the common DROs are basically the same unit but rebadged. I think. TouchDRO looks really interesting and if I was installing something from scratch, I’d definitely look at that.

When I bought my mill I put a cheap DRO on it. It’s a pretty straightforward process if you have any mechanical ability. I basically just put a few 1/4-20 (or some other thread, I don’t remember) holes into the castings to mount the scales and sliders.
I think I purchased mine from ebay, you can buy the scales in whatever length you need for x & y. It came with a ‘universal’ kit of brackets that was easy enough to make work.

There’s also some kits out there for the z axis that are pretty cheap. They basically just look like a modified digital caliper that’s mounted on it, although I haven’t had a need for that yet.

And @photon , that touch DRO looks pretty sick. I’m going to have to check that out. It looks like it will work with the scales I already have installed, I would just have to get the adapter doo-dad. (I already have a cheap android tablet)


Not relevant to the topic, just ranting here but the hand wheels on my mini mill are .0625" per revolution which is psychotic. I don’t know why it couldn’t be .050" or at least .060" which would still be divisible by 10. No idea why they did that but for that reason alone I am thinking about getting a DRO. My best guess is it’s a hobby machine for people who might have done woodworking so 5/8" is easy to understand… Except 1/8", 1/16" or even 1/32" increments are not precise enough for machining. At least there’s still .001" marks on the wheel too.


:slight_smile: Well, someone might come across this post and say, “Oh! That’s what they mean by counting turns on a milling machine!”


Woah that’s an insane increment. We have a Taiwanese bridgeport clone (wildly, J head genuine replacement parts seem to fit perfectly)

The scales on ours are .200" per revolution. What brand is your mini?

Thanks Photon! This is great info and I hadn’t heard of Touch DRO before. It seems like the total cost with Scales, Adapter and tablet might come in a touch lower than a full DRO Pros kit. The feature set looks great. I’ll chime in here with an update!

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As someone pointed out already, eliminating backlash is the killer app for a DRO, worth its weight right there.

The ability to have both absolute and incremental zeroes is super useful, plus you can add as many sub-datums as you want.

I like my Touch-DRO. I had a tablet and got some scales cheap, so the set up cost was easy to swallow. X-axis scale and reader mount was super easy, Y-axis took some creative thinking and making my own brackets, maybe an hour total. Mounting to curved castings like on a classic BP can add to the fun. But the pain of install is soon over and you’ll never have to do it again, it’s one-and-done. The electronics in the box, and the programming of the app, appear to be top-notch, but I’m no expert.

If you use a Z-scale on the knee, and another on the quill, you can call the quill the W-axis, and have TDRO sum the Z- and W-axes for you. The basic TDRO box has four inputs and the summing is done in the app. It also supports a probe and/or tach inputs, but I have no experience with that. My mill already had a tach (rpm readout), and I’m completely ignorant about probes.

One great thing about TDRO is how Yuriy the developer is so responsive to user questions and problems. He has a sponsored sub-forum on The Hobby Machinist forum and that seems to be a good way to present your Qs and problems.

I don’t think it’s a full-time gig for him; I think he still has a day job, though maybe he’s working toward making it full-time (or maybe has already?) Nice guy.


Grizzly. But I think most mini mills come from the same casting and use the same lead screws so that’s more of a mini mill thing than a brand thing. My grizzly lathe has .050" per rev on the cross slide and .040" on the compound. Who knows why the mini mills are like that…

Also I realized in my OG complaining post that I moved everything up a decimal place. It’s .0625 per rev.