Ideas on installing DRO onto Optima BF20-20 Mini-Mill

[Aussiephil]

This thread has come about to give one of the other members some ideas om how to mount up his DRO kit that came without brackets.

Whilst the kit i sourced from aliexpress did come with brackets they were effectively useless for this smaller mill and all the mounting was custom designed.

I did start taking photos during the process but sort of forgot to keep doing it so most of the install steps were not captured.

I'm lucky enough to have access to a 3D printer to custom print brackets and custom spacers so a lot of the time was just waiting for bits to print :)

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The trickiest bit in my opinion is the Y axis due to the sloping cast iron base, so the first set was to space the glass scale away from the table far enough that the scale and the read head can be mounted vertically. The designed spacer mounts via three counterbored holes to the cast moving table and the aluminium angle to mount the scale bolts to the spacer via the 8 holes you see above.

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the glass scale is also spaced fractionally away from the angle via a spacer.

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Now the Z read head is also bolted to a custom bracket designed to get it vertical in the Z plane, it's a bit hard to see in this photo but there is a bracket the read head bolts to with sloted mounting holes back to the cast iron base, but also under that is a spacer that was printed to shift the head into the correct plane in relation to the glass scale.... this allowed me to print a based bracket and a variable spacer.

I used the same concept everywhere i needed to space spacing for alignment or for screw length matching as i didn't always have the exact screw length on hand.

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The X axis is simple really bit has some in my setup a specific order of mounting things.
There is a rubber mat that protects the channel in the base that mounts to the sliding table via a couple of bolts. this provides a convenient mount point for the read head to be fixed in place and the scale to move.
A short length of ALU angle was drilled to mount the read head and then to the table... there is just, just enough room for the rubber mat to be routed under the bracket if you use slim line optical scales and counterbored low profile machine screws. Magnet read heads should need all the room and should fit without the juggle.
The scale is then mount to the table and ALU bracket above the read head... using the same thickness angle means everything aligns by default.

For both the X and Y the read heads are fixed and the scales move as they are mounted upside down to protect them from liquids and swarf.

I need to pull the Z axis cover off to grab some photos of that and that can be tomorrows job.

[doug3030]

Thanks for posting the pictures Phil. I am looking forward to seeing what you did with the Z axis too when you post those pictures.

Your Glass Scales are HUUUUGE compared to my magnetic ones. And of course you relied heavily on your 3D printer. I don't have a 3D printer. I am more of a metal bandsaw and grinder kind of bloke.

Obviously our installs will look rather different, but hopefully will work similarly.

I had identified the mounting screws for the swarf catcher as being the anchor point for the x axis mount, which I see you used as well. I still want to provide a degree of protection for the scales and reader heads on mine though they appear to be a bit more robust than yours. I think most of my mounting brackets and protection covers will be made from 2" angle iron and some small aluminium angle.

On the Y axis I am seriously thinking about having the scale as the fixed itam and the reader head moving with the carriage.

At the moment I am designing on the fly, scribbling on pieces of angle iron and then cutting and grinding to fit. I probably won;t get a lot done today as I am doing other projects concurrently while thinking about this one but I will post piccies when I have something worth posting.

[Aussiephil]

They may be huge in comparison to the magnetic scales and i would have liked to got magnetic ones but they were seriously out of my willingness to pay when glass will do the same job..... these are the slimline versions :)

Yeah i do rely one the 3D printer but nothing i've printed couldn't be done in metal, bent sheet metal for the angles and mill some slots for adjustments.

I used mostly aluminum as it's what i had lying around as i do a lot in aluminum and have a easy supply of the light gauge stuff generally.

OK here's the Z axis photos, yes i also fixed the scal and let the read head move, it's the easiest option though for others this is technically wrong as the scale ends up facing the wrong way. easy to reverse it now i think about it by having a l bracket slide behind the scale....

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Overall view with the cover removed. The read head moves and uses the two existing screw holes to mount the bracket. The only tricky bit is getting all the spacing away from the mill body correct.
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just a closer view of the read head.
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The spacer closest to the column gets the spacing alignment correct.
The green rectangular section provides the mounting points for the cover... i actually used one of the supplied covers :)
The printed washers are purely to space the bolt head out as i didn't have the correct length M5 bolt.

I hope this provides some ideas.

Cheers
Phil

[doug3030]

After a couple of weeks off with a bad back, I got back to this job today.

I got the Z axis working before my back went out and had some parts for X and Y fabricated. Today I got all three axes working.

Now that all the parts, except for a mounting bracket for the control panel, are constructed and tested, next job is to dismantle, clean up and paint all the bits then put everything back where it should be.

I am saving the mounting bracket for the control panel til last so that I can experiment with a few possible placements.

I will take some photos to post here as I go through the reinstall and hopefully it will help others at a later date.

[doug3030]

The parts I made for the three axes:

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Now one axis at a time installation photos after the parts were cleaned up and painted.

X-axis:

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You can see the magnetic scale on the aluminium angle. The cutout in the red square is access to the screws securing the reader head to the bracket. The cutout in the yellow is for the coolant drain port in he back of the mill carriage. The part in blue came with the mill. It holds the swarf catcher to the back of the carriage. I put in longer screws to go through that part, the rubber swarf catcher and the bracket I made, attaching the whole lot to the back of the carriage. I drilled and tapped two m5 holes in the back of the carriage to bolt on the aluminium angle through the round holes near the ends.

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Above is the bracket fitted to the back of he carriage, with the swarf catcher attached as well. You can see the platform for the reader head with the two mounting holes. The aluminium angle with the magnetic scale will go above the bracket.

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The aluminium angle and magnetic scale in place, the reader head has been installed by inserting the screws through the hole in the aluminium angle. A couple of adjustments and that's the x axis done.

Someone will probably be wondering why I didn't mount the reader head facing upwards instead of horizontal. Yes, it would have allowed a small amount more Y axis travel, but only a few millimetres. The advantage of doing it the way I did it is that the end of the platform on the bracket for the reader head protrudes a couple of millimetres past the edge of the aluminium angle. This provides protection for the reader head and aluminium angle from the swarf catcher and prevents the reader head being damaged by the column if the y axis is wound too far back. I thought that was more important than the last couple of millimetres that might never even be used.

I will cover Y and Z in the next post.

[doug3030]

The Y axis:

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So here's the problem axis, but it actually was not as bad as it initially looked.

In the purple rectangle are two holes tapped m4. Looks like a good spot to attach a bracket for the reader head.

The green rectangles indicate a couple of m5 holes with vertical ends milled into the sloping side of the base of the mill. They will be fine to attach a piece of aluminium angle to support the magnetic scale. I wanted to install the aluminium angle in such a way as to provide the maximum protection for the magnetic scale and the reader head which meant the scale needed to be under the aluminium and I needed to make e U shaped bracket.

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Here you can see the u shaped bracket attached to the side of the mill, running back and forth with the Y axis, moving the reader head along the fixed scale you can see at the top of the aluminium angle. I used some aluminium tube as spacers to position the aluminium angle an inch or so off of the side of the mill to provide clearance for the U shaped bracket to pass between the mill and the angle. A couple of minor adjustments and the Y axis is done.

Z axis:

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There was a recessed slot in just the right place for the magnetic scale, as shown in the picture so it was a simple matter to mount a bracket to the two m4 holes in the side of the mill head to hold the reader head on the scale.

All scales working:

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Next job is to work out where to mount the control panel and design a bracket to mount it.