I made a long holder that over lays each extrusion piece. The vertical plane is within 0.03mm the accuracy of the extrusion . The gap is very close, so that may be the source of error. I am not sure. The puzzle is the accurate 9.52 mm pitching in two different regions of the setup. I can modify the holder to increase the gap. But current gap is 0.2mm . I will try the other sensor with a different gap amount and see what the results are.

As you can see the reading of 9.51mm is quite accurate as the dial is about a 1/2 division short of the full 3 turns of the pitch.

I found a Newall option that is looking very good, but is beyond my current budget for this project. But it maybe that I just have to dig deep and make it happen.

Edited By Neil Lickfold on 21/04/2022 09:40:51

That is a kit I had not yet considered was the MDRO S7 kit. I set up the top or Y axis onto the unit, and they measure different values to each other, with neither of them working properly. Even with the added gap, 1mm, it made it no better at all. Obviously there is magnetic setups and Magnetic setups. I am inclined to think the error is in the tape itself. The only thing that really does repeat is the initial zero set for both scales. Neither did exactly 9.52mm for 3 complete turns, being more than .4mm over or under.

Thanks for the encouraging responses. I do use the taper turning attachment occasionally, so it is why I want the front DRO. The cross slide is less of an issue for me, but I need a setup that does not effect the attachment being connected.

It seems the buried system might be the way to go for the cross slide for sure.

Thanks again.

Hi Jason, I have used the plunger clock against the carriage as well, and the hand wheel is within 0.02mm every time. So 2 turns is anywhere from 6.35 plus or minus 0.01mm down the length of the bed. I was expecting it to be more error near the chuck, but that is not what I saw. I have been using a 0-50 indicator for the lengths up till now and was hoping this magnetic thing would mean I don't need to set up the semi cumbersome indicator. The errors I am seeing is a long way off. The two read heads on the one tape but at 160mm apart or so, give totally different readings as the carriage is moved along. But when returned to zero, they both read within 0.02mm of each other the correct original place on the tape. So even moving along 1mm they have a large error compared to each other and what it should be.

It came from Aliexpress. The bracket was I thought an issue, so I added a dti to watch the movement of the read head. It was less than 0.01mm as it was just the cable drag. No mater how it was retained, it was junk. I could try an MDRO system, but it needs to be front mounted so that I can still use the taper turning attachment. The tape has a 3m logo all over it. The exercise I thought was interesting and if viable was going to make a more rigid and better secured mount for the read head. I also thought that the double sided tape holding the extrusion holding the tape was the issue. But I could not measure any movement of that extrusion. I remeasured the extrusion and it was actually imperial extrusion , 5/8×7/8 with a metric 1.5mm wall. So an odd extrusion for sure. So when the holder was fitted into the extrusion with the read head, that width was 18mm so had 0.5mm gap from the fully closed position, and was 0.1mm in the vertical position clearance, leaving 0.2mm clearance between the read head and the stainless steel protective strip. So the max gap on My S7 is actually only 19mm wide by the halfnut mechanism in the carriage.

The magnetic system that people have shown has been very encouraging and it would be foolish to write it off already. I will look at the options again with new eyes and see where I end up with it.

Neil

Thanks Bernard for taking your machine apart and taking pictures. It is appreciated. The kit as it comes supplied, is the encoder always intended to be encapsulated into the bed, or does it hang off the back a bit under the nice cover that they supply? I understand that there needs to be a slot milled into the under side of the cross slide, but did not realise that the carriage needed to be removed and cut as well. ?

I have found a 16mm square cross section KA200 series glass scale that will allow for me to make the front mounted dro. So am happy about that. Also getting a Sino LCD SDS2-2-3VA and does have some axis summing as well if I want to combine the topslide with the saddle but will require some readout on the topslide of course. It is compatible with the mdro magnetic readers as well.

Neil