New TouchDRO install on column mill - critiques and suggestions sought

[Tomzo]

Greetings,

I recently completed what I am sure will be V1 of my TouchDRO install on my HF 33686 column mill/drill. I am new to all of this so comments or critiques are welcome.

I bought the DIY kit from Yuriy which is excellent. That soldered together nicely and other than a few stumbles on my part getting the USB wires connected right it has worked well. I downloaded an enclosure off Thingiverse for my 3D printer but had to modify it a bit to get the standoff holes in the right places. I liked it because it has a thin cover that when printed in white lets me see the "heartbeat" and bluetooth LEDs blinking.

This was mounted on a vertical surface just behind the mill and uses a little 5V power supply from Amazon that (hopefully) will prevent any interference from the motor on the machine. I still need to print a chip cover for that power supply.

 

[Tomzo]

I started with the Z Axis as I thought that would be the most challenging. I took everything off the front of the mill including what HF calls the "graduated rod" in their parts diagram. I then used a 1/2x13 piece of all thread and bolted it where the "graduated rod" was. I then squared up a chunk of aluminum to 1" x 1" x 2" and drilled and tapped a hole down the center. I also drilled and tapped two 5mm holes to hold the plate that connects to the DRO read head. I used jam nuts on the top and bottom of the aluminum block because there is slop in the threaded 1/2x13 threads. The jam nuts make it quite solid.

I used some scrap 50mm wide x 5mm thick aluminum bar I had on hand to create a plate that would bolt to my aluminum block and the reader. In order to get the spacing right I made little 3D printed standoffs for the scales. It took three iterations to get just the right thickness to make things pretty square. The scale is mounted to some 1" aluminum angle that is connected to the mill using the same threaded holes the plastic cover used. The angle was drilled and tapped to mount the scale. I will be making a sheet metal cover for the whole assembly that will mount to the holes on the right hand side that held the plastic front cover.

 

[Tomzo]

For the X axis I took off the bumper stops and the little metal stop/ I took some thicker aluminum plate and milled down the upper part of it that holds the read head. This allows the thicker part to be bolted to the cast iron base and leaves clearance for the 3mm button head screws that hold the read head. Here is the part from my design in FreeCAD:

Here is how that looks mounted to the machine. I also 3D printed little standoff pads (again with a few iterations) to get things spaced correctly.

I still need to fabricate some sheet metal chip covers for these and plan to use the slot where the bump stops were in some way. Or I will figure out something else entirely...

 

[Tomzo]

For the Y axis I think my design likely needs help. I measured the angle on the cast iron base side with a little digital angle meter and it came out to 3 degrees. I printed more standoff pads for the scale using that angle and, after a few iterations, I got the scale plumb and then used two pieces of aluminum with one bolted to the bed of the mill and the other bolted to the read head and the first plate. I had to really torque those screws to get this system to work without differential movement between the plates. I generally give myself 1/2mm or so clearance on through holes and at first the top plate would move but the read head's "sticktion" would resist movement until the bolts hit the side of the through holes. After some adjustments in my standoffs that got everything lined up I was able to remove that movement. I may find a thicker piece of aluminum and make this out of one piece.

I am also concerned about the moment arm I am making with the connection to the bed of the mill being so far from the read head. My calibrations came out great - I am within a thousandth on the Y axis when calibrating with TouchDRO. My skills are going to be the limiting factor not the DRO.

 

[Tomzo]

Anyway, I put some adhesive zip tie anchors in some key spots and restrained the cables. All axes have the head moving (with the x moving when Y is moving) and a fixed scale so I made sure to leave enough slack. I then got a cheap tablet holder arm from Amazon to hold the Fire8 HD tablet that runs the system.

If anyone has ideas on how this might be improved I am all ears. Now to make some chips with the system!

 

[brasssmanget]

Looks very similar to my IGauging set-up from awhile back....I've since switched over to a DRO also. Work looks good. Maybe think about covering/shielding slides from oil and debri a little......just as a precaution? JMHO

Never took pics of the new scales and DRO installed.....maybe when it warms up a bit I'll get some......

 

[Tomzo]

Yes - chip shields are on the list to do next for sure. Is the far end of the Y axis scale free floating in that install?

 

[DavidR8]

Nice work!
I've been hemming and hawwing over a Touch DRO for my South Bend lathe.
One thing I haven't been able to find is the resolution of the iGaging scales.
Do you know their resolution?

 

[Tomzo]

While I can't attest to this as I am not sure I can measure it, the specs on the iGaging store claim a resolution of 0.0005"

3 pc Set 6''-12''-24'' Absolute Digital Readout DRO S

iGaging's Absolute Origin DRO uses HIGH ACCURACY ABSOLUTE memory technology. It keeps track of its origin position once set. Whenever the DRO turned on, the easy-view super large LCD displays the actual sensor position ready to start measuring. It's not n

www.igagingstore.com

 

[Tomzo]

OK, so I got some chip guards installed today. I just used some roofing drip edge flashing which worked well on the X axis. I used the little slot bolts that held the bumper stops to install some little aluminum brackets. The edges are a bit sharp so I think I will 3D print some flexible end caps. The Y axis is a bit trickier in that the cover moves with the read head. I just attached a shorter section of flashing to the read head mount and it will cover all of the areas of the scale where the read head will travel. The far end of the scale will see chips, but won't ever see the read head.