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Hive13 Project
DRO 550 Front.jpg
Status: Complete
Start Date: 5/4/2014



This is a project to add a DRO to the Enco RF-30 Mill. This project is to build a DRO-550 which is an open hardware, open source DRO.

I also bought the base PCB for an LCD-200

Project Manager


What needs to be done

  • Fabricate covers for the X and Y scales (probably from 1 inch Aluminum angle)
  • Mount the DRO somewhere. Maybe an arm coming off the side of the mill?

What has been done

  • Bought the DRO-550 kit
  • Soldered the DRO-550 kit
  • Loaded basic Firmware
  • Did a power on test
  • Validated the voltage test points
  • Bought one 6" igaging scale (35-706-P)
  • After many hours of self induced problems, the scale is "talking" to the DRO550 correctly
  • Ordered parts for the enclosure from Mouser See: Enclosure Parts
  • Built the enclosure
  • Mounted the Z scale to the mill
  • Dave Lear loaned us the X and Y scales
  • Mounted the X and Y scales to the mill
  • Installed an 8 AA battery pack on the back of the DRO. (No more skipping).
  • Verified all three axis. They are within .001" over 3 inches.

Currently on the ToDo List

  • Mount the enclosure to the mill area

Design & Planning

Tried to connect the DRO550 to the igaging scale along with the igaging display head. Turns out they don't like each other. The igaging display head causes the DRO550 clock to drop out and they use a different refresh frequency anyway. If you want to verify the DRO550 display; record the measuring head with the the igaging diaplay head connected, disconnect the igaging display head, connect the DRO550, zero the DRO550, disconnect the DRO550, connect the igaging display head and move the measuring head some distance (say 1.000 inches), disconnect the igaging display head, connect the DRO550 and it should read the new value (1.000 inches).

Seriously, did this company not think their name wouldn't be pronounced "I gagging" as in "I am gagging". :)

I got to learn a lot about 21 bit data and clock signals . . . .

Tested the X Y and Z scales on the DRO550 and everything seems to be working. I noticed a jump in one of the scales (went from 0.000" to 2.000") when I was using the mill. Chased down that it occurs at least when the mill is shutdown randomly (not every time). I'm guessing that there is a voltage spike and the "inexpensive" power supply for the DRO can't filter it out. On the discussion boards there is a bit of conversation about this problem. Some people just went to a battery power supply to remove all the potential for a spike. The DRO takes from 9-20V so we could test that out pretty easily.




iGaging scale on Z axis of mill

Reference Links

File:21 Bit Protocol Scales.pdf

File:DRO-550 Software Guide.pdf

File:OpenDRO Users Guide 1.0.0.pdf

File:DRO 550 enclosure instructions.pdf

Nice setup for Z axis scale mount