Installing a magnetic DRO on my VM32L

[Ian PParticipant @ianp]

Really crude sketch of what I was trying to suggest earlier.

Something like 3/4" x 3/4" x 1/8" aluminium channel will be 1/2" wide internally which I think will be wider than the sensor head.

I have shown the channel sticking out at the back of the machine only to show that once you know the overall length of channel required it can be positioned offset towards the rear so that the rear end of the extrusion projects no further than the back of the machine base.

Hope that makes sense

Ian P

[Mike CrossfieldParticipant @mikecrossfield92481]

The arrangement Ian P describes is very similar to what I used on my mill, In my case the scale is mounted on a length of aluminium angle attached to the undeside of the carriage,, and there is also a swarf guard over it. The read head is mounted on an adjustable bracket attached to the base casting. Works very well.

[Iain DownsParticipant @iaindowns78295]

I'm having a think about the Y axis.

The saddle is 210 mm deep and the travel is about 230 mm.

With the length of the sensor around 40mm, I'd need about 310mm of channel which would leave 100mm sticking out the back.

The main advantage I can see with this approach is that I would be sticking the magnetic strip to a clean piece of metal and not to a suspect and rough painted surface.

I feel slightly uneasy about a 4 inch bit of 15mm channel sticking out of the saddle. Not sure if it's particularly justified!

Similarly, I've ordered some bar to replicate the Y axis mount in the pictures above – so I screw the bar to the column and stick the strip to the side of the bar.

I was thinking of spraying the strips with laquer after mounting to keep contaminants away from the sticky strips, but I'm not sure if the lacquer would survive the contaminants. Any thoughts on that.

Iain

[ChrisBParticipant @chrisb35596]

This is how I installed mine, possibly the simplest way to do it! The mounting bracket is just a piece of 1.5mm sheet metal, bent to match the angle of the milling machine base (the base casting has a slight slant to it) The bracket is slotted to allow for the readhead hide height to be adjusted.

The surface finish of the base might not be the same as that of a machined surface, but it's certainly fine for the magnetic tape to be installed on to. Installed this way you will not have any issues of anything sticking out.

My readhead and tape might be considerably smaller than yours but the length should be approximately the same. Have had no issues with it yet – my only complaint would be that some chips do tend to stick to the tape occasionally, but it's easy to wipe off with a brush.

[Iain DownsParticipant @iaindowns78295]

Somewhat to my surprise, success!

Here's how I added a (supposedly) manufacturers DRO kit to my VM32L.

Firstly, I didn't rate the brackets provided. I didn't even see that they could work.

So I made my own.

The X Axis was nice and easy. There's a 10mm slot which normally holds the scale. Rip the scale out (held in by pins), clean it up and stick the strip in there.

At some point, I'm planning to adjust the end stops (round button on left) with a rod so they can intercept an optical sensor int the DRO mount and provide a limit for power drive. However, that can wait.

To set it up I just put a feeler gauge between the sensor on the strip and tightened up

A word on cutting. I Kind of freaked about this. Is there some special way of cutting? Actually no. if it will cut metal just do it. I used tin snips, I drilled, I used a hacksaw. Careful though ,there seem to be some ridiculously fine splinters in the strip. Hacksaws aren't the best way!

I reckoned that the X axis in the slot would be fairly secure, but was less happy about the Y axis on the cheap paint of the body (meths seems to dissolve the paint. Ugh!).

So I drilled 3mm holes in the end of the strips.

In this case I stuck the stainless fascia to the strip before mounting it. For the X I mounted the strip then stuck the tin bit on top afterwards.

With the Y I drilled and tapped one end and used that as a reference for the other (bolted one end to the base and the made sure it was aligned).

You can see the bolts at each end in this picture.. I was happier doing this that using swarf covered magnets!

With this in place I hooked up the display and set it up and turned the handles. Whoo Whoo! The numbers changed!

Finally, I tidied up the wiring. I've used sticky mounts here rather than bolting the cable to the mill. Let's see if that sticks and if not, out comes the frill!

The DRO display is mounted on top of the motor control box. You can't really see it in this picture, But I think that's the best place for it.

I've not actually USED the thing yet, but I'm really looking forward to doing some real work with it!

Iain

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