Stand-alone Horizontal Macro Unit Design Questions

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Doppler9000
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Joined: Thu Oct 13, 2011 3:56 pm

Re: Stand-alone Horizontal Macro Unit Design Questions

Post by Doppler9000 »

Chris S. wrote:
Fri Sep 17, 2021 3:18 pm
Doppler9000 wrote:
Fri Sep 17, 2021 3:01 pm
My other question is regarding the StackShot controller - can I use it with 0.9* steppers?
Yes, absolutely. That's what I have in my rig. You might also check with Cognisys (the company that makes the StackShot) to see if they have on hand any stepper motors with 0.9 degree steps. Last time I asked about this--quite a while ago--they did. Before that, when I built my rig, they were kind enough to special order two 0.9 degree stepper motors that I had found online, terminate and test them, and send me the better of the two units. This for a very reasonable charge.

--Chris S.
I will reach out to Cognisys, thank you.

ray_parkhurst
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Re: Stand-alone Horizontal Macro Unit Design Questions

Post by ray_parkhurst »

Doppler9000 wrote:
Fri Sep 17, 2021 7:12 pm
Thank you tor this - a quick drawing would be very helpful.

I was going to use a undriven KR20 for the idler just for ease of fabrication, but wanted to check it was low enough in resistance.
No, a KR200XA won't work as an idler. It has far too high mechanical resistance. However, it would work fine if driven along with a matching KR200XA with an idler in addition giving support against stress in pitch direction. Here's a quick concept drawing:
.
Picture2_3.JPG
.
This seems a bit wasteful and overly-complicated, though it does give full support of the Z-Axis against yaw. However, if you could always ensure the weight of your bellows/camera/lens/etc was centered over the axis of the Z-Axis linear rail, then a single rail would suffice. In this case the original drawing could work, or you could make a symmetric second idler configuration as I've sketched below:
.
Picture3_3.JPG

Doppler9000
Posts: 110
Joined: Thu Oct 13, 2011 3:56 pm

Re: Stand-alone Horizontal Macro Unit Design Questions

Post by Doppler9000 »

ray_parkhurst wrote:
Fri Sep 17, 2021 8:09 pm
Doppler9000 wrote:
Fri Sep 17, 2021 7:12 pm
Thank you tor this - a quick drawing would be very helpful.

I was going to use a undriven KR20 for the idler just for ease of fabrication, but wanted to check it was low enough in resistance.
No, a KR200XA won't work as an idler. It has far too high mechanical resistance. However, it would work fine if driven along with a matching KR200XA with an idler in addition giving support against stress in pitch direction. Here's a quick concept drawing:
.
This seems a bit wasteful and overly-complicated, though it does give full support of the Z-Axis against yaw. However, if you could always ensure the weight of your bellows/camera/lens/etc was centered over the axis of the Z-Axis linear rail, then a single rail would suffice. In this case the original drawing could work, or you could make a symmetric second idler configuration as I've sketched below:
.
Thanks so much, Ray.
Do you have any photos that would help with construction details?

ray_parkhurst
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Re: Stand-alone Horizontal Macro Unit Design Questions

Post by ray_parkhurst »

Doppler9000 wrote:
Fri Sep 17, 2021 8:36 pm
Do you have any photos that would help with construction details?
No, sorry. It's fairly straightforward, except that you need to ensure good coplanarity between the KR rail carriage and the idler carriages (within same axis). This ends up being done with shims of some sort. It's also sometimes difficult to find the right lengths of idler rails, but they do come in a range of lengths from several sellers, and they're fairly inexpensive. I've contemplated getting longer idlers and cutting them to fit, but so far have not tackled that approach. The platforms can be anything, even wood, which would make construction easier. I don't show the bottom platform, but it should be of similar size to the other two. They could aso be aluminum cheeseplates, but it's unlikely the holes would line up with any of the components. I've seen some very nice thin (~1/2") laminated bamboo cutting boards that would be perfect for this app IMO. Three platforms of identical size, all lined up on their edges when at center of travel, would be visually informative.

One note about the motors...I've found it extremely useful to integrate dual-shaft motors into all my systems. I install Vexta Smart Dampers on the outer shafts, giving manual control as well as some vibration dampening.

Doppler9000
Posts: 110
Joined: Thu Oct 13, 2011 3:56 pm

Re: Stand-alone Horizontal Macro Unit Design Questions

Post by Doppler9000 »

ray_parkhurst wrote:
Sat Sep 18, 2021 5:28 am
Doppler9000 wrote:
Fri Sep 17, 2021 8:36 pm
Do you have any photos that would help with construction details?
No, sorry. It's fairly straightforward, except that you need to ensure good coplanarity between the KR rail carriage and the idler carriages (within same axis). This ends up being done with shims of some sort. It's also sometimes difficult to find the right lengths of idler rails, but they do come in a range of lengths from several sellers, and they're fairly inexpensive. I've contemplated getting longer idlers and cutting them to fit, but so far have not tackled that approach. The platforms can be anything, even wood, which would make construction easier. I don't show the bottom platform, but it should be of similar size to the other two. They could aso be aluminum cheeseplates, but it's unlikely the holes would line up with any of the components. I've seen some very nice thin (~1/2") laminated bamboo cutting boards that would be perfect for this app IMO. Three platforms of identical size, all lined up on their edges when at center of travel, would be visually informative.

One note about the motors...I've found it extremely useful to integrate dual-shaft motors into all my systems. I install Vexta Smart Dampers on the outer shafts, giving manual control as well as some vibration dampening.
Thank you, Ray.

ray_parkhurst
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Re: Stand-alone Horizontal Macro Unit Design Questions

Post by ray_parkhurst »

You're welcome! However...I see that I've made a conceptual error on the last diagram. If the Z-axis is placed below/behind the Y-axis, then when the Y-axis moves from side to side it will cause yaw stress on the Z-axis carriage. It's not due the movement itself, but when the Y position changes it moves the weight of the camera/lens/bellows/etc away from the Z-axis rail axis, and this will cause stress on the carriage. To eliminate this, the axes need to be swapped so that the bellows mounts to the Z-axis platform. This will allow you to fix the camera/lens/bellows/etc over the Z-axis rail axis. Here is an updated concept drawing:
Picture4_3.JPG

Doppler9000
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Re: Stand-alone Horizontal Macro Unit Design Questions

Post by Doppler9000 »

lothman wrote:
Thu Sep 16, 2021 8:24 am
Doppler9000 wrote:
Thu Sep 16, 2021 7:07 am
Lothar - do you prefer the KR26 for the travel or the build weight?
KR26 is "much" wider and much higher compared to a KR20 and therefore stiffer, a KR26 can handle 3x higher vertical loads than a K20. Think of the lever arm your camera setup has to such tiny sliders of a K20, especially in vertical setup. And with microstepping a 2mm pitch spindle is sufficient for 50x lens.

THK_Load.png
I just received a KR2001A and a KR2602B. The latter is substantially heftier.

Adalbert
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Re: Stand-alone Horizontal Macro Unit Design Questions

Post by Adalbert »

Hi Doppler9000,

I use THK KR2001A as follows:
https://www.facebook.com/photo/?fbid=12 ... 0269581589

Please note that the NA determines the DOF and therefore also the step size.
E.g. for a 50x lens with NA 0.40 you need different step size than for 50x with NA 0.80.

In my experience, the KR2001A is unfortunately a bit too coarse if you want to take many photos per DOF at high NA.
Better suited are drives of microscopes or very precise linear stages.

Best, ADi

ray_parkhurst
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Re: Stand-alone Horizontal Macro Unit Design Questions

Post by ray_parkhurst »

Doppler9000 wrote:
Wed Sep 22, 2021 1:24 pm
I just received a KR2001A and a KR2602B. The latter is substantially heftier.
If the length of the KR2602B is sufficient to give you enough overall movement, then the built-in idler is a big advantage. If not, then adding an idler rail to the KR2001A might give you more stability and possibly more overall movement. I used a KR26 for years, but when I built my current system I chose to build it with the KR2001A with idler.

Doppler9000
Posts: 110
Joined: Thu Oct 13, 2011 3:56 pm

Re: Stand-alone Horizontal Macro Unit Design Questions

Post by Doppler9000 »

ray_parkhurst wrote:
Wed Sep 22, 2021 2:13 pm
Doppler9000 wrote:
Wed Sep 22, 2021 1:24 pm
I just received a KR2001A and a KR2602B. The latter is substantially heftier.
If the length of the KR2602B is sufficient to give you enough overall movement, then the built-in idler is a big advantage. If not, then adding an idler rail to the KR2001A might give you more stability and possibly more overall movement. I used a KR26 for years, but when I built my current system I chose to build it with the KR2001A with idler.
It is a 300mm rail, travel is 155mm maximum.

ray_parkhurst
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Re: Stand-alone Horizontal Macro Unit Design Questions

Post by ray_parkhurst »

Doppler9000 wrote:
Wed Sep 22, 2021 2:44 pm

It is a 300mm rail, travel is 155mm maximum.
How much travel do you need?

Let's say you only need 100mm of travel. Then you could space the two carriages 55mm apart and achieve good "idler" action and stability. If you need 155mm of travel, the two carriages need to be zero-spaced. This is still better than a single carriage from a torque/stress perspective, but more space is better.

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