Ditron vs Sino...wich is better in your opinion

[rwm]

I set it up like this:

My 123 block measures 3.0005 in length. My DRO is reading this as 2.9986. That is an error of .0019. Way too much to accept.
On the 2" side I get very good correlation. I just seems like the scale is off in certain locations.

 

[mksj]

Pretty far off for a 1 micron scale. One can use the linear compensation to take some of that out. My scales came with a a reader head accuracy certificate, this 5uM reader head had an accuracy of +0.002 MM, -0.001 MM, but did not cover the full range of the magnetic tape. The supplied magnetic tape is suitable for either 5 or 1 micron heads, so it seems that the problem you may be having may be magnetic tape resolution if you get the same numbers/errors on the DRO at different distances. Yuri did a post on the different scales and found cyclical errors with magnetic scales similar to what you are encountering, which seem to be much worse than the Electronica/SRA scales. As I mentioned, I have checked the magnetic 5uM scales for accuracy and have not seen the level of deviation you are seeing with the Ditron magnetic scales.

DRO Scale Recommendations (for TouchDRO, and other DROs)

Good day, folks. I get a lot of questions about scale recommendations for TouchDRO, so for the last couple of weeks I've been testing a bunch of different scales. I intend to keep an updated list on my website: Recommended DRO Scales, but I think there is value to having a thread here. This is...

www.hobby-machinist.com

 

[rwm]

FYI- the magnetic tape for the 5um and 1um heads is different with Ditron. The 1um head cannot read the 5um tape.

 

[ycroosh]

I set it up like this:
View attachment 458329
My 123 block measures 3.0005 in length. My DRO is reading this as 2.9986. That is an error of .0019. Way too much to accept.
On the 2" side I get very good correlation. I just seems like the scale is off in certain locations.

Cyclic error is VERY common with Chinese Magnetic scales, and is pretty easy to measure. Take a look at this video:

(around 5 minutes in it covers cyclic error measurement). You might need to adapt this to your DRO display, but this will give you the idea.

Regards
Yuriy

 

[rwm]

Very interesting. Yes I think this is what I am seeing with similar error ranges.
So I called DRO Pros to see about using an Electronica scale. The gentleman there told me I should not use an Electronica scale, that the pin outs were different, that resoldering the DB9 connector was impossible and that the new scale could have different amperage and could break the Ditron display. After going through all those reasons he tried to sell me on a whole new DRO system from them. Very frustrating and not super helpful! Do they also sell used cars?
Yuri- I know you will know this answer. Is the pinout of the Ditron slim head different from the Magna Slim? I assume you have worked with both.

 

[pontiac428]

I heard the pinouts are different with Ditron, but I don't know why one couldn't re-pin the connector. It's a 9-pin connector doing 4-pin duty as far as I understand it.

 

[ycroosh]

Very interesting. Yes I think this is what I am seeing with similar error ranges.
So I called DRO Pros to see about using an Electronica scale. The gentleman there told me I should not use an Electronica scale, that the pin outs were different, that resoldering the DB9 connector was impossible and that the new scale could have different amperage and could break the Ditron display. After going through all those reasons he tried to sell me on a whole new DRO system from them. Very frustrating and not super helpful! Do they also sell used cars?
Yuri- I know you will know this answer. Is the pinout of the Ditron slim head different from the Magna Slim? I assume you have worked with both.

DRO Pros try very hard to sell their displays, and I've heard from some people that they can be pushy, but what he told you is a pile of BS.

1. The pinout is different, but it takes 5 minutes to de-solder and re-solder the D-Sub connector.
2. Regarding the Amperage thing: the brochure on their site (https://www.dropros.com/documents/MagnaSlim.pdf) states power consumption of 0.6W. At 5V this would be roughly 110 mA. There is no way a Ditron DRO will have a power supply that can be damaged by one of these.

I have the pinouts listed here: https://www.touchdro.com/store/diy-dro-glass-scale-adapter-v2.html#optionAElectronica/Ems

I use Electronica/EMS scales on my lathe's cross slide and a generic Chinese glass scale on the carriage. Total power consumption (including the 150mA that TouchDRO itself draws) is a bit under 250mA.

Before you throw money at this, one thing you should try to VERY precisely set the ride height to 0.5mm and make sure the read head is as parallel as you can get it. Ditron uses a funky amplification circuit that allows the scale to read "something" with a sloppy alignment. Also, is your Ditron scale slim or full-size? If it's slim, try contacting Ditron and swapping the head for a full-size one. In my experience, full-size heads have a bit less cyclic error (and work well with the slim track). The one I have I was able to get the error to about +/-0.0003" (0.0006" total error).

Also, keep in mind that even good quality 1um magnetic scales have +/- 5um of error.

Regards
Yuriy

 

[rwm]

All great information.
My scale is SLIM 1um. I cannot really fit a full size head due to multiple geometric factors. I have played with the ride height but it did not seem to change much. It is difficult to set the height to exactly .5mm. I have the slim scales so the stainless cover is recessed from the sides and protected by the wipers on the ends. I will make a .5mm shim gauge and attempt to reset the height.
I saw the reverse engineering or the pinout on your site. It clearly can be done.
I would love to just do a glass scale but they all appear to be too large. My lathe is not well designed to accept a DRO scale without interfering with something.

 

[WobblyHand]

If you find re-pinning the connector a bit intimidating, you can buy a M and F DB9 connector, and wire up an adapter cable. I'd use some heat shrink on all the individual solder joints, but you could do every other one. Once it works, copy it for the other scales. Then get hoods for the connectors and sleeve the cable for protection.

Sometimes freeing up the wires in the connector is tough, especially if the wires have RTV or potting on them. The Ditron 1um glass scales I have are not potted at the connector, and would be easy to re-pin. I used a slim glass scale on my G0602 lathe and had to get rather creative to mount the X axis. It barely fit.

 

[ycroosh]

All great information.
My scale is SLIM 1um. I cannot really fit a full size head due to multiple geometric factors. I have played with the ride height but it did not seem to change much. It is difficult to set the height to exactly .5mm. I have the slim scales so the stainless cover is recessed from the sides and protected by the wipers on the ends. I will make a .5mm shim gauge and attempt to reset the height.
I saw the reverse engineering or the pinout on your site. It clearly can be done.
I would love to just do a glass scale but they all appear to be too large. My lathe is not well designed to accept a DRO scale without interfering with something.

Makes sense. I was in the same spot. I have Rockwell 11x24 and the cross slide must have been purposely designed to make it as hard as possible to install a DRO