Thread: Poor Mans DRO

Looking good Dean.

I have installed the same (or similar) DRO system to my mill. It revolutionsed my use of the mill. No more counting hand wheel rotations and then trying to workout allowance for backlash.

Being able to zero at a particular datum position when working on a piece and knowing you can easily go back at any stage without remembering how many rotations etc. is great. I also could not justify a more expensive DRO and have been happy with my decision.

Simon

I am still working at it when I get time. This is a night time job.

Most of the time spent this week has been working out how and where. To avoid loosing too much Y axis movement I have decided to position the scale below the level of the table. I have spent a lot of time trying out various positions and then checking clearance. The biggest problem is having room for a cover over the top.

Dean

Finally got time to do some more. My other jobs seem to take longer than expected for some reason.

X Axis Dro.jpg

The X Axis scale in position. I quickly squared up the table to mill the 2 brackets for the ends. This was before I started the thread about the square. I just dialed from the end of the table, but this is not very well machined. The picture shows the table back to front again. I have used the same read head connection method as with the Z Axis. I will also use this for the Y Axis. Yes that is rust on the left edge of the picture. It appears to be where the casting did not clean up. I could not crop it out.

When I started typing this post I realised that I did not swing the table around to its normal position and check how it all fits. I am sure that given all my careful measurements it will all be perfect.

I need to work out a cover for this and the Y Axis scale and then sort out the wiring so it does not get snagged.

When I had attached the scale to the table I measured from the top surface of the table to the top of the scale at each end. I got measurements within a few hundedths with a digital caliper and a parallel sitting on the table top.

Dean

When I swung the table back to its normal position I found that the fit of all the bits was not too bad. The issue here is that the rubber way cover for the Y axis has to fold up between the read head and the mill column. It appears that I will lose a few mm movement, but I won't know for sure untill I get the read head chip cover in place to see how much it will flatten the folds of rubber without too much pressure being applied. Maybe there is another way to protect the ways. If I could get the way cover to lift up with one fold in the middle, with springs it would be great. I would not lose any movement at all. I need to do that without it lifting at the back edge of the ways tho. A roller?

Y Axis Mounting Bar.jpg

I milled a bar for the mount. This has a slight plinth under each of the 2 caps screws (Black Arrows) and behind the rear cap screw it is relieved to a depth of about 2mm as there was a slight interference with the base casting at the position of the Red Arrow. The bottom of the bar sits about 1mm above the way surface level. When checked for parallel with the Y axis, this bar was about 0.23mm closer at the rear so I fitted a suitable stainless steel shim under it. All good so far although I did cut the bar too short at the front. I did not leave enough room for the M5 screw for mounting the scale. I had to weld a bit back on and skim the surfaces again. I wish I had some toe clamps to clamp this sort of work to the table.

Extended Tap.jpg

Mounting the bracket to connect the read head to the mill base. I just managed to fit the drill in to drill and tap the top M5 screw, but I only managed to drill the bottom hole progressively by extending the bit out further in the chuck until it only had about 6mm grip. I drilled a bit of steel rod to a little undersize from the cross measurement of the tap's square shank. I placed the tap most of the way into the vice held by soft jaws and tapped the tap into the hole (actually the hole onto the tap). One of those jobs where the setup took way longer than the work. As shown, I tapped the hole with my lttle drill with the clutch set to prevent breakage. I use this drill a lot for small tapping. This hole took about 4 seconds, so I reversed out and did it again. The tap/extension is only about 1-2mm above the raised edge of the casting.

Level Check.jpg

I have lost count of how many times I levelled the scale every time I set up and marked a new bit for mounting, then pulled it all apart again for drilling etc. The X axis had lots of room to work in, but the Y axis was far more restricted for space. Each time I levelled the scale I got it within 0.02mm on the DTI as setup here.

Y Axis Mounted.jpg

The last scale finally in position. As you can see, I have used the same method to connect the read head on all 3 scales, but I reaslise today that the spring arrangement on the X axis does not provide impact cushioning in both directions. I need to replace the threaded rod with a longer one and rearrange the spring position. I hope this feature is never needed, but as I have the means why not make use of it.

Next I need to order the chip covers. A local business has the means to bend the shape I want. I have no idea what thickness steel they carry, or how much it will cost. Not too much I hope. They make trailers etc. I think I would like around 1mm thick.

I have also decided to move the readout panel to the other side of the mill. Probably obvious to everyone else. It will of course be easier to read there, but also out of the way of the Z axis locks and a bunch of power points that I have to lean over to reach, generally putting my hand on the readout panel for support. I would like to move these points closer, but I don't know where to put them without moving them to a totally new location. The readouts have the cable (USB) coming out the left side and loop back to clamp to the side to keep it secure (see picture in last post). This means that a much wider plate is needed to mount them on the other side of the mill head. I am trying to work out how to mount them on a pivot from the rear column so I can adjust the position and move it out of the way if needed. What I mean is how to do it without spending any money on it.

After that is done I can organise the cables.

I am happy to have got this part finished. Tonight I even pulled out the 'Michael Made" 3 ball handle and started to arrange to put it in the lathe so I can set the Taper Turning Attachment to machine some clamping blocks so I can drill/mill the holes to attach the handle to the lathe and attach the crank handle.

Dean

I finished fitting the DRO scale chip/coolant covers today. It cost $20 to get them made. Nicely done. I got them done with 1.6mm galv so they have quite a bit of strength.

DRO Chip Covers.jpg

Red arrow points to X axis DRO scale cover. I had to trim about 13mm off the end of the rubber Y axis way cover and the end bit bent over to hold it straight. (Blue arrow) This was to clear the left hand end of the Y axis DRO cover. I am very happy with the result.

Unfortunately when I was working on the Y axis scale mount (last post) the read head decided to throw in the towel. All I get is constantly changing random digits. Discovered it the next day of course. Sigh. A new one is on the way, a 12inch scale DRO that is.

I am still waiting on the loom tube to tidy up the wiring and I am still working out how to move the readouts to the other side.

I worked out that I have lost about 10mm of Y axis movement. I could move the upper end of the Y axis way cover up the column a bit and drop the X axis DRO scale cover abit and gain half of that, but I don't think it is worth it at the moment. The X axis DRO cover is acting as a stop for the Y axis. Works pretty well.

The 3 ball handle for the lathe will have to wait a bit longer as it was the Y axis DRO that I needed most for this.

Dean

Hi Dean, Can you please advise supplier of your DRO -I have been using a HAFCO unit- it was working OK yesterday but numbers just keep rolling over today - Hafco say not serviceable, I guess I will have to go back to the old way with fixed stops??
Alf Scotting

Sorry for the late reply. I haven't been on for a couple of days. My original set came from General Tools and Supply Co and the replacement which I received Thursday, came from Taylor Toolworks. Both of these were bought via EBay. I have no issues with General Tools. It is just that when I ordered the replacement Taylor Tools had the best price. I did an EBay search for "Igaging DRO".

I have not found a way to reverse the values which means the Y axis reads positive when the table is travelling forward, the opposite to the wheel readings.

I am planning on having the read head turned around to correct this. Does anyone have any other method to deal with this?

I will need to make yet another set of brackets to mount the read head to the mill base. I hope to get this done today. Then I only need to finish tidying up the cables and I will be finished except for squaring the table to the Y axis.

Dean

I have finished installing the DRO except for squaring the table precisely.

DRO Readout Arm.jpg

The Readout Panel is mounted on an extension arm that started life as a work light.

DRO Readout Panel.jpg

The Readout Panel in position.

Dean

Originally Posted by Oldneweng

I am planning on having the read head turned around to correct this. Does anyone have any other method to deal with this?

That is what I had to do when I was using the normal LCD readouts. When I upgraded to using Touch DRO it has a feature which allows you to reverse the reading ... too late for me as I already rotated the read head.

Originally Posted by Vernonv

That is what I had to do when I was using the normal LCD readouts. When I upgraded to using Touch DRO it has a feature which allows you to reverse the reading ... too late for me as I already rotated the read head.

Thanks Vernon. That is what I thought was the case. Seemed strange to reverse it, looked strange, but cannot be seen now the cover is on. All good.

Dean

Hi!

Does it really matter which way the numbers travel?

I honestly cant tell you off the top of my head which direction my DRO works, i just use it.

Simon

Originally Posted by simonl

Hi!

Does it really matter which way the numbers travel?

I honestly cant tell you off the top of my head which direction my DRO works, i just use it.

Simon

For the direction of positive travel to be technically correct apply the "Right Hand Rule". A quick search will find lots of information on this.

Originally Posted by Techo1

For the direction of positive travel to be technically correct apply the "Right Hand Rule". A quick search will find lots of information on this.

Fair enough. I know for a fact that my Z axis does not conform to convention. My Z increases when I extend my quill, not retract it. It doesn't really matter to me but when I'm boring a hole, I figure the depth should increase, not decrease. Either way, it's just the change in numbers I look at, not the sign. Simon

Does it matter? I don't know. But it seemed like a good idea at the time.

I have made all the DRO units run the same way as the hand wheel scales.

My Z axis also increases as the quill is extended. I thought that would be the most obvious.

Dean