Advice on DRO mounting on Myford VMC

This is my first post so I hope I’m in the right place/ forum for this question. Please guide me if not.

I am going to fit a 3 axis DRO and have a few questions rattling around. There are so many great historical posts on here these have answered many however I’m left with some areas where advice would be most welcome.

1. Is M-DRO with 5um magnetic encoders a sensible choice (I am assuming there’s no point paying more to go to 1um and I’m very happy with the M-DRO mag 5um I put on my S7.
2. has anyone done a really nice job of mounting the brackets etc for the Z axis?

3. Some people mount the magnetic strip directly on the table ie not in an aluminium extrusion - how robust is that?

4. Any close up photos of a M-DRO / Myford project would be really helpful

Any guidance or advice would be really helpful.

John D,

First, welcome to the forum. It's a shame that you've received no responses to your enquiry. I suspect that there are few owners of a (specifically Myford) VMC mill on here with Machine-DRO magnetic scales fitted. That's a pretty narrow field. I was reluctant to reply myself, for those very reasons, but I can't keep my trap shut! So.......

A quick Google reveals that Machine-DRO have a few photos of a DRO installation on their web site

Myford DRO install

Admittedly they look like glassin their example, not magnetic scales, but the mounting principle is similar. Have you contacted them for their views on the subject?

I have a Warco VMC; virtually identical to the Myford version and I had to fabricate all the mounting brackets from angle aluminium that I happened to have lying around. Not aesthetically pleasing, perhaps, but functional and robust for all that. There are some pictures in my Warco VMC album. The Z-axis was a little awkward in as much as the vertical face of the body to which the scale is attached is NOT vertical. I measured the angular difference with a digital angle gauge and made up a couple of spacers with one side machined to that angle and drilled through to accept the mounting screws, thus providing mountings which were truly parallel with the Z-axis slide ways.

The right angle joints are secured with elongated slots so as to obtain articulation of the mounting to assist in the alignment.

It doesn't answer your original question, but I think you are going to have to bite the bullet and be a trailblazer for your particular machine/DRO combination. If you do, share your results on here, for the benefit others in the same position.

Afterthought: Granted the magnetic scales are smaller and, arguably, easier to mount, but I have found that glass scales, though bulkier, can be accommodated reasonably easily on the VMC. It's a hefty bit of kit for a home workshop. And they're cheaper!

Hope that helps,

John H

I have a VMC with X and Y glass scales. I've never bothered with the Z. However a late freind of mine did and his solution to the casting slope was to machine a piece of aluminium channel to compensate for the slope. The channel was then bolted bottom face out to provide a flat vertical mounting surface for the scale. The provided angle bracketry connected to the knee as above with the slotted pieces providing enough adjustment to get everything in the right shop. The magnetic scales are small enough to fit to the quill in front of the depth stop and with the addition of a combiner box allow for the quill reading and the Z axis to work as one unit.

regards Martin

Definitely 5 um is 'good enough' on a milling M/C or dare I say any M/C. Can't comment on M-DRO specifically as I have a Warco DRO on my Myford VME mill.

Tony

Cannot help with mounting scales on a Myford but 5um scales should be OK for your milling machine. 5um = 0.0002" !um scales are more suited to a surface grinder.

My solution to the sloped / not quite flat / not quite parallel / at right angles mounting surfaces when I fitted the Z axis scale to the knee of my Bridgeport was to use sharp right angle aluminium L section and car body filler to define the mounting surfaces.

I bolted two suitable lengths of the L section, probably 2" x 1/8", together in a T shape taking care to ensure the top of the T was truly flat and aligned. I probably used clamps and some shorter bit of L running crosswise to hold things together. Having examining the machine I decided which surface to use as the master then drilled and tapped a couple of holes so one side of the T could be bolted on with the joint line between the pair of L sections aligned with the joint on the machine.

After preparing the surface on the non-master side I spread a sufficient layer of body filler on to cover both the slope and imperfections and spread a layer of cling film on to stop the filler sticking to the alloy. Carefully bolting the T on to the master side with a couple of thick washers interposed to ensure it sat flat forced the excess filler out to create a flat surface. Might need a bit of massaging to sit it down if you were over generous with the filler.

Once all had set I removed the alloy, filled a couple or three pits an made it all smooth and true. Drilled a couple more fixing holes on the filled side and repeated the process on the master. Almost faster to do than describe.

Having a pair of properly accurate surfaces to work off made fitting the scale and its cover a breeze.

Clive

Thank you everyone for such helpful replies. I was worried that having not contributed before it was considered bad form to pile in and ask for advice.

I went for the M-DRO mag 5um and its waiting in its box for me to have had a good night's sleep and some time to be brave enough to fit it.

It was good to see a couple of different approaches to mounting the Z axis strip and encoder. I think i will try and do what you show in the photo, John H as it feels least intrusive for a machine that is in nice original condition.

I like the idea of including the quill in the Z axis inputs, Martin. I need to reed up on a 'combiner box'

I'll post some pictures once done.

Plus one on the combiner, I fitted one of these to my 626: M-DRO Summing Interface . If you are going to fit DRO on the Z might as well go the whole hog.

William.

Thank William. I think I will do just that. Do you have any photos of your install you could share?

Welcome to the forum John. Don't worry about starting with a question, more the merrier!

Dave

Not the best photos I'm afraid but should give you an idea: 626 Mill Album - photo below shows the finished job. It was quite a fiddle and I made a bit of a meal of it but it works well, I sacrificed the quill stop and used the threaded rod to fix the angle iron brackets. With a less bulky scale (as I think the magnetic ones are) it would be a simpler job. The fine feed knob is removed for visibility.

William.

I fitted a Machine-DRO set to my Myford VM-C, and it was not easy!

Doing so lost the long-travel stops on the front of the table Some will aver that hardly matters but I would have preferred to keep them as an adjunct when needing make many long cuts: set them by the numbers then simply traverse the table (manual feed only) to the stops. I used the stop-block's mountings to hold the sensor; and a strop cut from an expired, plastic association-membership card as a feeler-gauge for setting the gap.

That was the easy one.

The cross-travel became a confection of aluminium angle, under the right-hand of the knee.

The vertical strip is on the rear of a vertical 2 X 2 X 1/4- inch aluminium-angle upright fitted with spacers for verticality A front cover-strip and cap cut from 3mm PVC sheet completes the enclosure on three sides, to protect the DRO strip and sensor.

My approach throughout was to shield everything as much as possible to protect it from swarf and coolant (brushed or sprayed on, not pumped). This works but did complicate the already awkward task of fitting a system to a machine not designed for a DRO in the first place. It means having to make "wraparound" brackets to go round all the corners.

.

Incidentally I do not use the DRO every time I use the milling-machine. For short tasks I often still use the hand-wheel dials.

Overall though I am happy with having installed the system. It has certainly made life less fraught. I have even managed to make parts that fit together without over-drilled or slotted screw holes!

The big bug-bear though came with the machine; nothing to do with the read-out. The quill is too stiff for the return spring and makes sensitive use almost impossible; and this seems incurable.

Thank you William for the photos - really helpful to see. I'm not troubled by the fine feed on the Myford so hopefully a bit easier as more clear space.

Nigel, out of interest, did you use an optical or magnetic DRO? I want to get it right first time (in terms of the holes I drill and tap at least. Its such a nice machine and it doesn't deserve extra drillings! I'm using magnetic. With my kit, the depth of the strip in the extrusion and cover isn't that much so was planning to drill the back of the table to mount it there (but i need to check if this would limit my Y axis travel and if so by how much). I was hoping the X and Y axes (what's the plural of axis?) would be the easy ones with the Z requiring the head scratching. Theres no way I can see of avoiding the confectionary of brackets you speak of if the encoder is to approach the strip from the rear and remain protected from the shrapnel coming from the business end. Like you, my plan is spacers on the right hand of the column to bring an aluminium extrusion parallel with the dovetails. I was thinking though, that there is a small pretty flat area on the front face just next to the vertical dovetails that could be wide enough to mount tabs to support the strip offset by a few mm to clear the oil filler on the knee. I think some spacers would still be needed but the encoder bracket simpler as it would be bringing the encoder round by 90 degrees, rather 180 degrees from the knee.

Like you, the quill is stiff so that it doesn't (quite) return under its spring. Have you stripped the quill/ gear down to clean things up and it not fix things? If so that will save me a job as I'll not bother unless there are other reasons to do that. I have got a really clean copy of the manual. If you would like a hi-res scan I could do that.

John -

Plural of axis is axes.

Mine uses magnetic strips. Machine-DRO supply quarter-round shields to help shelter everything, and I fitted that along the front with sealant.

Another thing I did was support the flexible tubes, which are not intended to become soaked in fluid, hold the cable by P-clips where necessary. Where they go round the left-hand side of the knee they enter a short length of plastic corrugated hose - caravan waste-water tube - held to the knee by a split-clap machined from a PVC block.

The cables then rise to the arm holding the electronics off the side of the machine column, close to its top. This should be enclosed tightly of course, but I do have a clear plastic cover draped very loosely over it to keep it clean, including from my oily fingers.

Normally I am shy of drilling and tapping holes in my machine-tools, especially the older ones, but felt it justified here.

I have been pondering how to make suitable end-stops without losing too much travel. One idea I have is a pair of dovetail clamps, perhaps machined from aluminium-alloy plate, or of mild steel with soft "jaws" , to fit the table ways, to hold some form of stops or to be the stops themselves.

Regarding the quill, I have a copy of the manual complete with sectional drawing and parts-list but it gives no clues on how to overhaul the thing.

Nigel,

I see that you have the same x-axis power as me. The following photo may give you some food for thought on mounting the travel stops and power feed limit switch stops

To clarify; it consists of a BMS strip mounted on stand-offs bolted to the dovetail in the front face of the table. The strip is drilled to accept the power feed limit switch actuators and slotted to accept the travel limit stops. It helped that Warco supplied a 400mm scale for the x-axis, which left room at the ends to fix the stand-offs. The travel stop actuator was incorporated into the x-axis read head mount, seen more clearly in another of the photos in my Warco VMC album.

In practice, I have found I never used any of these stops and removed the set-up very soon after fitting it, to be replaced with a longer, 600mm glass scale. That was prompted by the failure of the 400mm z-axis scale, so the original 400mm unit was repurposed in that position.

John

John H-

Not this Nigel!

I don't have a power feed on my milling machine.

Also, the encoder strip has taken over the T-slot that held the stops, for the table's full machined length, and the read-head occupies the spot once used by the fixed stop. So I can't do as you have done.

Sorry, Nigel. Brain fade, again. I would say "back to the drawing board" , but that's a bit of a sore point I guess.

John

Thank you Nigel!

No, not that sore a point. See my 'What I Did Today'!

John D,

Only just seen this post. There are photos of a Machine-DRO installation on my Warco VMC in one of my albums.

B

I've been cleaning everything ready for assembly and fitting the DRO. The worm gears on the vertical lead screw/ knee rise/ fall were caked in old grease and dirt. I removed the knee and cleaned with petrol. Does anyone know how to remove the worm gears to be able to get to the bearings (the one on the vertical lead screw and the ones at either and of the handle shaft)? I am worried that by cleaning all around there that i will have flushed the lubrication out of the bearings. Should I replace the bearings or is that a pain?