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

[rwm]

I just reset the ride height using a .5mm shim and then pulled out the shim. I see no difference. I still get almost a .002" error on my 123 block.
Yeah, I've got gib screws, carriage lock, compound lock all in the way, plus a close back splash that limits travel. I only have 135mm X travel but when you use a 150mm glass scale and add in the longer read head it gets pretty long.
Wobbly- can you post a link to the glass scale you used?
I'm looking at some glass scales now. Some might fit. Unfortunately Ditron seems to make the most compact! I hate to spend any more money there!

 

[WobblyHand]

I just reset the ride height using a .5mm shim and then pulled out the shim. I see no difference. I still get almost a .002" error on my 123 block.
Yeah, I've got gib screws, carriage lock, compound lock all in the way, plus a close back splash that limits travel. I only have 135mm X travel but when you use a 150mm glass scale and add in the longer read head it gets pretty long.
Wobbly- can you post a link to the glass scale you used?

My bad, it was a Sino KA500 1um glass scale. Bought it from:

https://www.aliexpress.us/item/3256804255469925.html?spm=a2g0o.order_list.order_list_main.10.69be1802Y1PtU3&gatewayAdapt=glo2usa

It had the same pin out as the Ditron. It is 18 x 20mm. It had the smallest glass read head I could find, (70mm long) when I was looking. Hope this helps!

Hymseann (the AliExpress vendor) is not awe inspiring, but they did deliver the part when they said they would. I had to cut mine, which was fun, since the glass is mounted at an angle, but it wasn't too hard to do. About $90 including shipping...

 

[rwm]

Thanks!
The 18 x 20 mm profile is great. The problem is the length of the read head. It takes up so much travel that the scale becomes too long overall. Even if I cut it down to 150mm travel it would be 262mm overall. I think I can do about 230mm max.

 

[WobblyHand]

Thanks!
The 18 x 20 mm profile is great. The problem is the length of the read head. It takes up so much travel that the scale becomes too long overall. Even if I cut it down to 150mm travel it would be 262mm overall. I think I can do about 230mm max.

I moved my backsplash further back by 40mm. It wasn't that hard. I spot welded two pieces of 1 x 1/8" steel to my backsplash, and drilled new holes. My scale is 288mm long. One end sticks out 45mm towards the backsplash. The other end sticks out towards the operator. I get full travel of my cross slide. My cross slide will fall off the screw before it hits the relocated backsplash. I printed the black bracket to hold the read head, thinking I'd replace it sometime. At the moment, it works well enough that I can't see a reason to machine the bracket out of metal.

 

[rwm]

That is an elegant install!
On my machine that would cover the screw that locks compound rotation and all the cross slide gib screws. It would interfere with the carriage lock as well. I could move the back splash but it would be a total redesign.
My old crappy lathe had a cut up caliper as a capacitive DRO. It was more accurate than my new Ditron. Kind of pathetic.
Hey what is involved in cutting a glass scale? How hard is this?

 

[pontiac428]

That is an elegant install!
On my machine that would cover the screw that locks compound rotation and all the cross slide gib screws. It would interfere with the carriage lock as well. I could move the back splash but it would be a total redesign.
My old crappy lathe had a cut up caliper as a capacitive DRO. It was more accurate than my new Ditron. Kind of pathetic.
Hey what is involved in cutting a glass scale? How hard is this?

I haven't done it yet, but people have posted their experience here (all good, IIRC).

A friend who is a wood worker just put glass scales on the RF-31 I sold him a few years ago. He thought about it long and hard, then put the scales in his compound miter saw with a carbide toothed wood blade and chopped them in one bite, three times they came out butter side up. I figure if that works, you could reasonably expect to do the job with an axe and have it work out. If Ditron ever gets back to me, maybe I'll find out myself even sooner.

 

[WobblyHand]

Cutting the glass is easy. You have a lot of leeway making the cut, basically all you need to do is make sure any cracks don't propagate more than about a third of the read head length. The pickup is roughly in the center of the head. I just cut off the length with a saw, preferably carbide tipped. Pretty much a caveman job. I trimmed to length with a carbide end mill. Ideally you want to avoid crap getting on the scale. I used clay stuffed around both sides of the glass, and cut through it all. It wasn't the cleanest job, but it really doesn't matter. Everything gets covered up by the end cap, which you will need to reglue. I used RTV.

 

[WobblyHand]

That is an elegant install!
On my machine that would cover the screw that locks compound rotation and all the cross slide gib screws. It would interfere with the carriage lock as well. I could move the back splash but it would be a total redesign.
My old crappy lathe had a cut up caliper as a capacitive DRO. It was more accurate than my new Ditron. Kind of pathetic.
Hey what is involved in cutting a glass scale? How hard is this?

My scale covers the gib screws, but everything is easily removable to adjust. (Four screws.) I need to install a low profile lock on the front side. After considering the alternatives, this was the least bad option. In practice, this install has worked out very, very well.

 

[rwm]

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.

 

[mksj]

Wasn't aware of the high variance in accuracy of magnetic DRO scales until Yuri posted his review. I have magnetic scales from Electronica and SRA/Machine DRO in the UK. They specify the accuracy of their magnetic tape to be+/-0.02mm over 1m, but state in practice if installed correctly they normally achieve much higher accuracy. Their heads/scales are quite small (you need to specify 5 or 1 micron heads), the Electronica on my mill are bigger, although I believe they have a slime line type. The magnetic tape/cover can also be directly mounted to a surface. My tailstock scale is a 5 micron and tracks perfectly to the dial scale per each revolution. At the time I bought my magnetic scales Electronica and SRA/Machine DRO were to only ones offering them that would interface with standard TTL quadrature square wave output.

High Accuracy Magnetic Linear Tape

Magnetic scale tape. Suitable for the 1, 5 and 25 micron resolution magnetic tape encoder head. Supplied in 100mm increments up to a maximum length of 25 metres single piece.

www.machine-dro.co.uk

M-DRO EH-01 - 250mm/ 10" Reading Length Magnetic Linear Encoder

M-DRO EH-01 linear magnetic encoder with 250mm (10inch) reading length. A compact encoder profile suitable for a wide range of machine tool, XY tables, jigs and metrology applications. The encoder beam can be cut to length to suit install

www.machine-dro.co.uk