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

[WobblyHand]

After looking at the glass scales carefully, I cannot make any of them work. If I mount the read head between the ways, the scale must cover the lock for the compound rotation. If I mount it outboard of the ways the entire backsplash needs to be redesigned including moving the whole machine out some. I think I am stuck with magnetic scales, unless someone comes out with a read head that is 50mm long or less.
I just need to optimize the magnetic approach. At this point that may mean buying an Electronica scale and see if I get improvement. The Ditron is nowhere near their published specs.

The magnetic read heads are definitely smaller. It was a challenge to fit in the 70mm glass read head onto my lathe. FWIW, my factory mag DRO installation blocked access to the gib screws. It didn't block access to the lock though. But the factory DRO resolution was only 0.001" radially, which was too coarse.

Good luck on your search for a smaller mag read head. If I find one I'll pass along a link.

 

[rwm]

MKSJ- That is super helpful! At a minimum I could go with the M-Dro. It looks like they are available with reasonable shipping. I have some inquiries out about the Electronica.
I could also still return the entire kit to China. About $150 to ship which is not terrible. But that would leave me without any good solution. I have no problem with the DRO display so I would be OK keeping that. I think I will keep the Ditron kit and try to improve on the X accuracy.
My assumption in all of this is that the linear encoder is the problem, not the DRO display unit. I can't see how anything else would cause these issues but I am no expert here. Yuri seems to agree that this is a mag tape issue?

 

[WobblyHand]

MKSJ- That is super helpful! At a minimum I could go with the M-Dro. It looks like they are available with reasonable shipping. I have some inquiries out about the Electronica.
I could also still return the entire kit to China. About $150 to ship which is not terrible. But that would leave me without any good solution. I have no problem with the DRO display so I would be OK keeping that. I think I will keep the Ditron kit and try to improve on the X accuracy.
My assumption in all of this is that the linear encoder is the problem, not the DRO display unit. I can't see how anything else would cause these issues but I am no expert here. Yuri seems to agree that this is a mag tape issue?

Could be the tape, or the head, it takes two to tango.

 

[rwm]

@ycroosh - I have another question if you see this. In studying your pinouts it appears that The Electronica scale uses RS422 output using all 9 pins. The Ditron has either RS422 or TTL with TTL using fewer pins? How do I know what my display head wants to see and are these compatible even with swapping appropriate pins?
Edit: I just opened up one of my DB9 connectors. I see 6 wires plus a shield wire that goes to the metal housing. This does not match up to the pinout Yuri has on his site. Not sure if this is RS422 or TTL? It looks like the Electronica is only RS 422 with 8 wires in use. Maybe these are not compatible? Is the RS 422 inherently more accurate than the TTL?

 

[Gaffer]

Yuri- I have another question if you see this. In studying your pinouts it appears that The Electronica scale uses RS422 output using all 9 pins. The Ditron has either RS422 or TTL with TTL using fewer pins? How do I know what my display head wants to see and are these compatible even with swapping appropriate pins?

I hope to get my lathe assembled and the Ditron glass scales installed in the next few weeks. I'll report back on the accuracy. Also, when you want to ensure a particular member sees your post like Yuri, type the user's name @ycroosh, and it will notify them. As you begin to type their user name after @, you'll see their user name appear and can click on it to insert it.

 

[rwm]

Thanks! I did not know that!

 

[Boswell]

TTL means that it just directly uses the voltage levels of TTL integrated circuit logic. 0v-5v. Less than .8v = logic ZERO while greater than 2v = logic ONE. It does not have any inherent noise rejection and suffers from voltage drop over distance. RS-422 on the other hand uses differential current loops that allow it to run much longer distances (specification says up to 1200 meters and because of the differential pairs it has very high noise rejection.

 

[rwm]

@Boswell-that is good to know. But I assume that means they are incompatible systems. If the Ditron read head is TTL and the Electronica scale is RS422 they are not interchangable.

 

[WobblyHand]

@Boswell-that is good to know. But I assume that means they are incompatible systems. If the Ditron read head is TTL and the Electronica scale is RS422 they are not interchangable.

Actually, 90+% of the time they are compatible, especially over short distances like 3m. Unless you have a huge amount of electrical noise in your shop, and long distances, the ttl outputs are fine. I have a vfd on my lathe and ttl dros and there are no issues on my glass scales.

 

[rwm]

Actually, 90+% of the time they are compatible, especially over short distances like 3m. Unless you have a huge amount of electrical noise in your shop, and long distances, the ttl outputs are fine. I have a vfd on my lathe and ttl dros and there are no issues on my glass scales.

How would I hook up an 8 wire read head to a Display that wants 5 or 6 wires? Can some be unused?