THK KR15 cheap on eBay

mawyatt · Post by **mawyatt** » Sat Oct 27, 2018 11:19 am

Here's what I've done with the US Automation THK KR15 bases rails. They are used as X&Y subject positioners. I've removed the electronics and mounted a small cable connector directly to the NEMA11 motor. One KR15 is mounted directly to the other KR15 stage at right angle with a couple low profile M3 bolts. The bottom KR15 is mounted directly to a long ARCA clamp, or to a Thor Labs 95mm clamp.

I'll post info on the Precision Stack and Stitch system based on these.

Anyway, hope this helps those with the USA KR15s.

Best

JohnyM · Post by **JohnyM** » Sat Oct 27, 2018 11:30 am

My system looks exactly identical but i have rotating and 2x goniometer stages instead of ball head.
Question, when you removed "electronic compartment" from the motor, there were 2 shims there that made motor rotate smoothly. How you managed to keep them in place?

mawyatt · Post by **mawyatt** » Sat Oct 27, 2018 12:04 pm

JohnyM wrote:My system looks exactly identical but i have rotating and 2x goniometer stages instead of ball head.
Question, when you removed "electronic compartment" from the motor, there were 2 shims there that made motor rotate smoothly. How you managed to keep them in place?

The US Automation rails didn't have any shims, or I didn't notice them

The rails and motors run smoothly and are very quite, much more than my KR20!!

Best,

ray_parkhurst · Post by **ray_parkhurst** » Sat Oct 27, 2018 5:15 pm

Looks very good Mike. Only thing different about mine is I added an idler rail that runs beside and parallel to the bottom rail. I was concerned about lateral torque on the bottom rail. Otherwise, these all should look similar.

It appears you did not remove the casing that holds the electronics, just swapped the PCB with a different "cap" or interface board, or maybe with your own controller? Did you cut down the casing? I think the shims JohnyM is talking about are between the casing and the main motor housing. The casing also includes the rear motor bearing, so you can't really remove it, but you can cut it down without causing any issues.

JohnyM · Post by **JohnyM** » Sat Oct 27, 2018 5:35 pm

Exactly what Ray said. It takes qute a lot of space (% of whole assembly) and i also want to use it on microscope stage.

Question: what those rubber bands are for? Recognition of controller + rail?

mawyatt · Post by **mawyatt** » Sat Oct 27, 2018 5:44 pm

Thanks Ray.

I just removed the two PCBs from inside the rear housing and routed the motor wires to a connector which I glued to the top slot opening in the cover.

My electronics are just the Raspberry Pi 3B and the 3 controllers, nothing else is needed except the opt-isolators for the camera and strobe trigger outputs. I'm waiting on the connectors. I'll put a green and red LED for the camera and strobe triggers, so you can tell when they are triggered. I have them now on a Proto board.

I'm running a test run now moving the X and Y axis 29,000um and Z axis 45000um with 5000um steps. I'll start a much longer run while I'm watching the World Series.

BTW I wrote all the code in Python, and it's original. I didn't want to use the language and procedures that are used by CNC and 3D printers, wanted it to behave the way I want and not doctored up to use some other code and routines.

Best,

mawyatt · Post by **mawyatt** » Sat Oct 27, 2018 5:52 pm

JohnyM wrote:Exactly what Ray said. It takes qute a lot of space (% of whole assembly) and i also want to use it on microscope stage.

Question: what those rubber bands are for? Recognition of controller + rail?

Good question. They are fundamentally a strain relief for the cables and connectors, but also serve a color coded identifiers. My controllers also are color coded as is the software routine and controller serial code numbers.

Helps with debugging and setup.

Best,

viktor j nilsson · Post by **viktor j nilsson** » Mon Nov 19, 2018 3:54 pm

Got round to pulling out the electronics boards and soldering+shrink wrapping the motor wires to Mjkzz's cable tonight. Not pretty, but that's ok. Must say I was quite excited when I powered up the controller and saw it start moving.

Next up, attachment plates. I also think I'm going to hook up the limit sensors. How damaging is it to run these things too far?

ray_parkhurst · Post by **ray_parkhurst** » Mon Nov 19, 2018 4:05 pm

viktor j nilsson wrote:
Got round to pulling out the electronics boards and soldering+shrink wrapping the motor wires to Mjkzz's cable tonight. Not pretty, but that's ok. Must say I was quite excited when I powered up the controller and saw it start moving.

Next up, attachment plates. I also think I'm going to hook up the limit sensors. How damaging is it to run these things too far?

It shouldn't hurt the rail to overtravel it. The rail has rubber bumpers on both ends to protect it. The motor will simply stall until the movement currents cease. When you set the travel limits, the controller senses that the motor currents change when it hits the end of travel, and the controller automatically sets a limit slightly shorter than point where the currents changed. At least that is what the mjkzz controller does from my interpretation of what happens when the physical limit is reached. Perhaps mjkzz can give more info on this feature.

viktor j nilsson · Post by **viktor j nilsson** » Mon Nov 19, 2018 4:10 pm

ray_parkhurst wrote:
viktor j nilsson wrote:
Got round to pulling out the electronics boards and soldering+shrink wrapping the motor wires to Mjkzz's cable tonight. Not pretty, but that's ok. Must say I was quite excited when I powered up the controller and saw it start moving.

Next up, attachment plates. I also think I'm going to hook up the limit sensors. How damaging is it to run these things too far?
It shouldn't hurt the rail to overtravel it. The rail has rubber bumpers on both ends to protect it. The motor will simply stall until the movement currents cease. When you set the travel limits, the controller senses that the motor currents change when it hits the end of travel, and the controller automatically sets a limit slightly shorter than point where the currents changed. At least that is what the mjkzz controller does from my interpretation of what happens when the physical limit is reached. Perhaps mjkzz can give more info on this feature.

Oh great, many thanks, Ray. Then I don't think I'll bother with the limit sensors. Enough cables as it is.

ray_parkhurst · Post by **ray_parkhurst** » Mon Nov 19, 2018 4:21 pm

viktor j nilsson wrote:
Oh great, many thanks, Ray. Then I don't think I'll bother with the limit sensors. Enough cables as it is.

One thing though...when the rail reaches the physical limit, and the motor stalls-out, it can cause quite a jerking motion. This can be disconcerting, or may even dislodge a specimen if not well-mounted. Just a caveat to be aware of...Ray

mawyatt · Post by **mawyatt** » Mon Nov 19, 2018 6:04 pm

viktor j nilsson wrote:

Got round to pulling out the electronics boards and soldering+shrink wrapping the motor wires to Mjkzz's cable tonight. Not pretty, but that's ok. Must say I was quite excited when I powered up the controller and saw it start moving.

Next up, attachment plates. I also think I'm going to hook up the limit sensors. How damaging is it to run these things too far?

viktor,

Looks great!! These are great little controllers, now you just need to get 3 of these in synch and talking to each other for a full S&S setup!!

The USA KR15 have a total range of about 32mm from stop to stop, so I use 1mm from the motor stop and define that as zero, and have a range limit of 30mm from there. This generally keeps the rails within the stops. One thing to keep in mind if you are using very fast stepper speeds without deceleration capability (the MJKZZ stand alone controller doesn't have acceleration or deceleration capability), the rail can overshoot and hit the stops and you'll lose position when running near the stops. Might be a good idea to stay within the limits mentioned just to be safe.

The NEMA 11 motors in these USA KR15s have a 5.6 ohm winding resistance and max current limit of ~670ma I recall, so they will get somewhat warm when running at full current since they'll be dissipating ~5 watts.

Keep us posted on your progress, this is very interesting.

Best,

ray_parkhurst · Post by **ray_parkhurst** » Thu Jan 17, 2019 8:25 pm

viktor j nilsson wrote:Looking very good, Ray. I must have missed the thread about your bellows, must check that out. I have one of those huge old Pentacon M42 bellows. In general I'm ok with it, but the front leg protrudes so far forwards that I sometimes bump into my xyz specimen holder. I'll probably change it for something else at some point.

My project is slowly moving forward. Got the controller and complementary motor cable from Mjkzz yesterday (thanks Peter!). The KR15 arrived a week ago. It is indeed very small, but with a very nice, solid feel to it. Still waiting for the linear guide rail from China. But in the meantime I'll try to get the KR15 operational.

Viktor...do you have an update on the KR15 system? Or did you publish in another thread? I'm curious how it turned out...Ray

ray_parkhurst · Post by **ray_parkhurst** » Thu Jan 17, 2019 8:26 pm

JohnyM wrote:Well, my pair will (hopefully) turn into microscope stage
I find 30mm travel too small for anything else than micro (mine starts from 10x)

JohnyM...same question for you...any update? ...Ray

viktor j nilsson · Post by **viktor j nilsson** » Fri Jan 18, 2019 2:05 am

ray_parkhurst wrote:
viktor j nilsson wrote:Looking very good, Ray. I must have missed the thread about your bellows, must check that out. I have one of those huge old Pentacon M42 bellows. In general I'm ok with it, but the front leg protrudes so far forwards that I sometimes bump into my xyz specimen holder. I'll probably change it for something else at some point.

My project is slowly moving forward. Got the controller and complementary motor cable from Mjkzz yesterday (thanks Peter!). The KR15 arrived a week ago. It is indeed very small, but with a very nice, solid feel to it. Still waiting for the linear guide rail from China. But in the meantime I'll try to get the KR15 operational.
Viktor...do you have an update on the KR15 system? Or did you publish in another thread? I'm curious how it turned out...Ray

It's moving forward, but grindingly slow with two kids and little spare time. Over Christmas, I used my father-in-laws' drill press to drill and tap all the holes in the adapter plates. I then realized, however, that my M3 screws had too high heads for the KR15 (as mentioned by mawyatt, so I haven't put it all together yet. I should get the low-profile ones this week however.