[How do I?] Sino KA-200 Scale mounting question

[SeattleJack]

The Sino KA-200 slim scales are the smallest glass scales i've seen - 16mm x 16mm. The only thing to becareful about is that they come in 1um and 5um and of course i ordered the 5um by mistake!

Subscribed and watching to see how the new scales fit your machine.

I am glad to find someone who has a KA-200 scale in hand and can probably answer my question.

I am in the process of adding a DRO to my South Bend 10K lathe and this scale is the only 1um glass scale small enough to use on the cross slide. In reviewing available information I find this statement in the SINO Linear Scale Installation Guide ---- "The cable on the KA-200 reading head is factory installed on the right side. Installation on the left side is available if requested." Every photo on line shows the cable on the right side and this statement leads me to believe that the scale can only be installed with the back side against the machine it's installed on. My installation will require the cable to be on the left side so I emailed the sellers on eBay and AliExpress to ask if they could provide same. They responded that I can just install it with the front side against the machine but I am reluctant to take the risk so I emailed SINO with the question of where can I get one with the cable on the left but have not received any response after a week.

So I am hoping you can answer the question -- "Is there something about the KA-200 that would prevent it being installed the other way around with the cable exiting to the left?"

Thank You for your time!

 

[SeattleJack]

@SeattleJack - Happy to follow this conversation in a dedicated thread if you'd like. As @WobblyHand mentioned i think the scales could be flipped easily from end to end to allow the cable to be on either side of the read head. The KA-200 is nice as you mount a back plate and the scales mounts to the back plate along with the cover.

View attachment 461126

You might not hear back from them right away as i think it's a national holiday over there currently.

Thanks very much for the quick response. Is that a picture of the backside of the KA-200 scale with the reader removed? It appears that the scale frame extends all the way to the ends and there are no removeable end fittings that I usually see on glass scales. Perhaps the end fittings are only on the front side and attached with the two screws beside the mounting holes. Does the edge of the end fitting that I see at the ends of the scale stand a little proud of the mounting surface so it would need to be trimmed to avoid putting a bend in the frame from the preload of the mounting screws.

Here's a picture of my situation. Do you foresee any problems in my future??

 

[WobblyHand]

You might want to take a look at this for some additional information. https://www.toolpros.net/wp-content/uploads/2020/07/KA-sereis-linear-scale-installation-guide.pdf It has some info on the KA-200 and installation information.

 

[ivel03]

I happen to still have the KA-200 unmounted as it didn't fit quite correctly on my lathe. I ended up with a broken piece on the read head carrier and contacted the ali express seller and they sent me replacement parts. It needs the read head guts moved from the broken read head to the new one but i never got to it as i ordered and installed a magnetic scale instead. I've attached pics in case it's of use to you - make and offer + shipping and it's yours. To be clear this is a project - as it was going on the ELS the end was cut off and it will need a DB-9 connector and i think i used and/or lost the screws but they're typical small metric screws readily available. If nothing else it could be used as a mock up for making the brackets and such to mount a scale.

Here is the thread where i mounted the scales on my lathe:

ELS Conversion on Weiss 1127

I have started the conversion of adding an ELS onto my lathe. Here are some pics of the progress: I'm happy with the stepper motor mount - it is very rigid. I plan on doing a bit more fit and finish on the stepper mount. The encoder mount i'm redoing b/c the bracket kicks slightly...

www.hobby-machinist.com

As you can see from the pics the head carrier has holes in either end but the unused end has a plug in it. You could also swap the scales end for end as wobblyhand mentioned. I can't think of a situation that flipping the scales wouldn't work...

Thanks very much for the quick response. Is that a picture of the backside of the KA-200 scale with the reader removed? It appears that the scale frame extends all the way to the ends and there are no removeable end fittings that I usually see on glass scales. Perhaps the end fittings are only on the front side and attached with the two screws beside the mounting holes. Does the edge of the end fitting that I see at the ends of the scale stand a little proud of the mounting surface so it would need to be trimmed to avoid putting a bend in the frame from the preload of the mounting screws.

Here's a picture of my situation. Do you foresee any problems in my future??

The way the Sino scale works is that the end cap (shiny part on the end with the hole in it) has 2 screws that holds it onto the main housing. Hopefully you can see it but the frame with the rubber strip goes to the end caps. The read head travels to just shy of the end cap. In my first pic there's the cover, the mounting plate and the scale. You will mount the mounting plate to the cross slide. These fasteners are countersunk in the adjustable slots. Then the scale is mounted flush to that with the 2 end holes. There is some adjustment in those holes to allow for leveling. There should be no bending of the frame if mounted as i described. Then the read head is spaced out appropriately from the saddle so that it is in line with the scale. Look through my mounting thread, it covers both this scale and the mag scale i ended up going with.


The issue that you may run into is one many of us have - how short can the scale be to fit on the side of the cross slide yet be long enough to get full travel forwards and backwards? That is the question.

 

[lesrhorer]

DRO scales in general are differential. That means, they merely report to the DRO controller when they move and how much. There are some very much more expensive systems that actually track the absolute position of the read head, but such things are never necessary in a hobbyist shop, or indeed the majority of production shops. Every differential DRO controller of which I know has the ability to switch the displayed direction of travel of the read head. Indeed, it would not make any sense to me to produce a differential controller which did not have that feature. The bottom line is it really does not matter what the orietation of the read head is relative to the device on which it is mounted. It also does not matter whether it is the scale body or the read head which is stationary and which is mobile.

On most lathes, especially smaller ones, metrology on the cross slide is going to be challenging due to size constraints. Often one must give up some travel somewhere, even with a compact scale. In my case, I gave up a little bit of travel on the tail stock. It cannot get as close to the carriage as when the scale is not mounted by about 1". In general, it also means modifying something. In the best of worlds, it will only be the mounting brackets that need modifying, or perhaps new brackets will need to be made. One should expect this. Unfortunately, something on the lathe may need to be modified over and above drilling and tapping some holes. 'Not great, but sometimes inevitable. Certainly modifying the brackets is preferable whenever possible. Modifying the scale is also possible, but personally I would avoid it.

You might find some tips here or here