Grizzly Lathe G4003 DRO installation

I purchased a Taishi 2 Axis Digital Read Out with precision linear scales for my Grizzly Lathe G4003. The DRO was $265 which seems like a good deal, especially when you compare the price to the Grizzly brand DROs that retail between $700 and $800!

The DRO unboxed

Taishi 2 Axis Precision Linear Scale DRO
Taishi 2 Axis precision linear scales for my Grizzly G4003
GC8900-2D DRO

DRO Scale Dimensions

After I ordered the DRO from I got a message from the vendor ( asking me for X axis and Y axis dimensions. For the Grizzly G4003 I sent them dimensions 6.76” x 30.75” (175 mm x 785mm). The DRO was shipped from Guangzhou, China and arrived on my doorstep remarkably in a little over a week. (If I did this over ever again I would add a quarter inch to the size of each scale to ensure the scale is never the limiting factor in axis travel.)

DRO X axis

The DRO came with a manual on how to operate the DRO screen, but there were no installation instructions. Buried in the Amazon reviews was a recommendation for watching a YouTube clip by DROPros which I did watch and found very instructive and useful.

The DRO pros video recommended using double sided tape to test drive the setup. I purchased the exact type (3M double sided outdoor tape) but I found the tape to not be strong enough to work in my case. Perhaps if I had wiped down the surfaces more or let the tape set longer it would have worked, regardless it didn’t work in my case and I abandoned the double sided tape fit up attempt.

The Scotch outdoor mounting tape didn’t work for me for the dry fitup of the DRO

3D Printed Shim

There was a 0.08 overhang where the fixed sensor head was going to be placed. I decided to quickly model shim to the exact dimensions required and printed it to take up the gap. Entire print time of this shim? 9 minutes! Sweet!

A 3d printed shim for my G4003 Grizzly Lathe DRO
A 3d printed shim to take up the gap on my Grizzly G4003 lathe cross slide

Time to drill and tap!

The DRO shipped with variou lengths of 4mm – 0.7 screws. I drilled the linear scale fastener hole closest to me with a 3.5mm drill bit first and then tapped this hole. This was also my first opportunity to use my drill and tap straight-alignment guide fixtures. (I bought these at Cabin Fever Expo 2020). I used a transfer punch to set the location in the middle of the slotted hole on the linear scale end.

The Big Gator Tools tap guide I purchased at the 2020 Cabin Fever Expo ensured my threading was straight and perpendicular. It exceeded my expectations.
Tapping the lathe cross slide for the X axis DRO
The DRO scale was installed the the cable routing solution was not ideal

I did each step very iteratively. After drilling and tapping the first hole I re fit up the scale and then punched the second hole. I drilled and tapped that and then after successfully mounting both of the holes for the scale I did each home for the sliding sensor one at a time as well. Take your time and iterate.

My DRO Dilemma- cable routing

After I mounted the X axis scale I discovered a new dilemma; the cable routing up and over the saddle was highly unsatisfactory to me. Searching for answers I stumbled across an internet post where someone was recommending you mill a small slot and route the cable straight through and under the slide itself. Initially I scoffed at this idea but later came to realize this was the only workable solution. This was going to require some serious disassembly on my Grizzly G4003 lathe!

Removing the Grizzly G4003 Saddle

WARNING: Getting the saddle off is a major pain on the rear! the rear ways weren’t too hard to get off but there were 2 fasteners on the front side that I simply could not reach with my wrench. Perhaps there is an alternate way to get these Seriously hard to access fasteners off is unknown to me, if I had to do this again I would write Grizzly for advice. Ultimately I had to loosen the upper saddle cap screws and then slip a hack saw into the slit between the upper and lower components to cut the 2 roll pins connecting it to the base so I could shift and slide the upper part of the saddle left or right to get to the final inner way fasteners. I was extremely displeased at the end of this because I accidentally nicked my cross slide wheel with the hacksaw when cutting the roll pins. My lathe is going to have some battle scars after the installation of the DRO

Milling my Grizzly lathe saddle in my Bridgeport milking machine

Milling a slot

Milling a slot in the saddle with a round nose endmill

The DRO cable can now route directly under the linear scale to the back of the lathe. Success!!!

DRO cable routed through a slot milled in the saddle

Y Axis

For the Y axis I mounted the scale directly to the bed. It should be noted the bed is a casting so it has a slight draft angle. I used a single washer as a spacer and a carpenter level for the initial layout. I milled a flat bracket 1/4” piece that could screw directly into the prexisting chip cover holes and put vertical slots in the bottom to fit up the sensor. I 3d printed a slotted block to take up the gap between the plate and the sensor. I put a matching angle in the slotted 3d block.

My understanding is the G4003 and G4003g are very similar in form, fit, and function. The G4003G is the gunsmith model and has a few more upscale features, but it is my assumption the concepts presented here should work on the G4003g model as well.

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