Digital Caliper as a Digital Readout on Small Mill

Is there a way to use a digital caliper as a digital readout on a small mill. See, Harbor Freight tools sells this little Micro Mill for under $300 but it is, in traditional Harbor Freight quality, very inaccurate. If you could add some digital calipers to the slides and use it as a digital readout,this little mill’s potential would be greatly increased. So, is this possible?

Sure it’s possible however the mounts are the part you need to be worried about and chips. Chips can serevrly mess up a digital caliper. As for mounting the best way would be to clamp the jaws to the table and then to fabricate a chip shield so that the calipers are protected. As for how to clamp the jaws it totally depends on the parts that you are using. The ideal solution would be to have a set of calipers that have replacable jaws so that you can take the jaws off and use the screw mounts to attach the jaws.

The other option is just to use a dial indicator and a magnetic base.

Actually sounds like a pretty good idea to me. Those cheapie calipers that are made out of composites could be easily drilled for mounting hardware and the reset function of the calipers would be a great addition to a small mill.

Kinda funny you ask this, as I was looking around this site last night, and came across exactly what you are talking about…
definitely check out this site if you are thinking about the mini mill from harbor freight. This site has all kinds of accessories, and every replacement part for that mill.

Our machinist was talking about doing this on his z-axis of his home machine. So, it must be a pretty good idea.

You should be able to do a google search and find a “home machinist” list that gives detailed instructions on how to do this.

Some things to watch out for…

  1. the caliper will have some backlash. You are not getting an absolute signal. Even though you don’t have to worry about the sloppiness in your machine, you do have to worry about the slop in your caliper.

  2. get the axes of the caliper and the machine axis aligned as closely as humanly possible. This will probably involve machining the holes on your milling machine and the caliper using someone else’s milling machine.

Check out Shumatech for a DIY DRO project


Interestingly, we just installed a digital readout on our old Bridgeport mill a couple months back, and it did wonders for our machining. I didn’t install it, but our mentor, Mr. Shinta did, and he would be happy to explain it to you. If you PM/email me, I can put you in touch with him on getting your readout attached.

This year all of theam 388s milling work was done on an homier mini mill converted to true inch using a kit from micromark
the mill comes with screws that do 1/16" per turn, which requres conversion to do normal measurements such as .060" the kit changed the mill to .050" per turn which helped alot. Thiese are good little mills IMHO my mill has an r8 spindel to be compatable with larger mills, you can get more information on theise at
the harbor freight, homier, grizz, ect. mills are all made by the same company in china with only small differences in the brands, color, spindle(r8 or mt2) and accessories included. From all of theise I chose to buy mine from homier
because they were having a tool show near my home and I could go pick it up to save shipping costs, also homier was the cheapest vendor of them to start with. Ok now back onto topic

You can use digital scales as a DRO however their are digital scales avalabe ment for this purpose try searching on ebay for “dro quill kit” I have seen listed scales up to 36" listed and there probally is larger if you needed them.

The readings can be viewed directly from the scales, or you can build an external display such as the shumatech one (I am currently building this one, will post info when completed) for around $250 you can have an entire dro system. Not only will the shumatech unit display the data from chinese scales but will calculate bolt hole circle locations, act as an tach for your mill or lathe, and you can interface quadrature encoders to it if you want to build your own scales.

The chinese scales are basically the digital calipers stripped of their jaws with mounting brackets attached to the ends and to the scale body. What some people have done with calipers is to drill mounting holes in the jaws and use either brackets or directly mount the caliper via the jaws to the mill or maby fabricate a set of caliper jaw holding clamps you could mount to the ways? You can acheve absolute readings via the zero button on most of the calipers you can also use most of the calipers (using the cheap chinese ones here) as metric dro also, could be useful sometime? There are pics of vairous caliper and scale mounts in the shumatech group, as well as the GrizHFMinimill group.

Links to theise great little tools
Minimill Yahoo groups
Shumatech website
Shumatech yahoo group
Homier mobil merchants

On our mill we have a screen about 15" lcd that has measurements down to the same as our fancy calipers. Its great zero anywhere and tell it to move anywhere else I love our mill.

I’m the NA marketing agent for the SHAN brand of measuring products. We
have some high quality digital scales are available from
They have digital output ports. DRO’s will be available from them soon.
SHAN-Precision and Allen Designs sponsors Lakota East Team 1038.

We have a special deal for First Robotics clubs. Measuring instruments at
cost are available to teams. Contact Patrick Allen 513-489-3181 or
[email protected]