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 DIY zoom - powered via eMotimo TB3 
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Joined: Tue Nov 24, 2009 7:55 am
Posts: 948
Location: UK
Post Re: DIY zoom - powered via eMotimo TB3
ardpub wrote:


On further testing, I managed to get some decent results with some consistency for two of my lenses with focus/zoom rings that are easy to turn. I definitely still need to up the gear ratio to get more torque for my other lenses and even more importantly, better accuracy. Even the two lenses I've gotten to work will stall when pointed upright (:29 seconds).

Setting focus marks with the TB3 controller's side-to-side movement is tricky (better gear ratio will help with that) but I'm also quickly discovering that the benefits of Dragonframe may outweigh the inconvenience of having to have a laptop .

(note: the first shot is only 2-axis)

Hi,
Good to see you are making progress. If you look at my image parts_MG_6831.jpg further up the page you will see the motor is set at an angle on the mount bracket so that the "flat" of the motor body is against the lens body. Hope that makes sense, it allows me to use a smaller gear than the one you are currently using.

MikeA.

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http://www.vimeo.com/user1214873/videos
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Wed Apr 10, 2013 7:17 am
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Joined: Thu Feb 10, 2011 1:35 pm
Posts: 23
Location: New Orleans, Louisiana, USA
Post Re: DIY zoom - powered via eMotimo TB3
The promo video is finished. It hasn't been officially realeased yet but I put it up unlisted on YouTube. Thanks for everyone's help with my rig buildout. I successfully used the third motor for both zoom and focus for shots that made it into the final cut but it still needs more torque and gear reduction to work effectively with all my lenses.

The motor I am currently using is the Nema 11 from Phidgets, Scothtape.

MikeA, thanks for the note. Im using "zip" style lens gears which only give my 7 or 8mm of clearance. If I implement a larger gear ring with spacing, I might be able to use a smaller gear but leaning more toward using a worm gear or something to get even more precision and torque.




Sat Apr 27, 2013 5:36 am
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Joined: Thu Feb 14, 2013 12:24 pm
Posts: 284
Post Re: DIY zoom - powered via eMotimo TB3
Thanks.

I got those NEMA 8s and I didn't realize how small they were.
I also ordered the 11s just in case... hopefully they work.

Otherwise I might get these 14s
http://www.pololu.com/catalog/product/1208

These things get hot!


Sun Apr 28, 2013 5:38 pm
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Joined: Tue Nov 24, 2009 7:55 am
Posts: 948
Location: UK
Post Re: DIY zoom - powered via eMotimo TB3
ardpub wrote:
The promo video is finished. It hasn't been officially realeased yet but I put it up unlisted on YouTube. Thanks for everyone's help with my rig buildout. I successfully used the third motor for both zoom and focus for shots that made it into the final cut but it still needs more torque and gear reduction to work effectively with all my lenses.

The motor I am currently using is the Nema 11 from Phidgets, Scothtape.

MikeA, thanks for the note. Im using "zip" style lens gears which only give my 7 or 8mm of clearance. If I implement a larger gear ring with spacing, I might be able to use a smaller gear but leaning more toward using a worm gear or something to get even more precision and torque.

]


Hi, Like the video you seem to have cracked the lens motorisation :D I use these gears from Jag35: http://jag35.com/dgear.html . I will check the clearance later and post.
Edit: clearance with my 24-105mm lens is 12-13mm.

MikeA.

scotchtape wrote:
Thanks.

I got those NEMA 8s and I didn't realize how small they were.
I also ordered the 11s just in case... hopefully they work.

Otherwise I might get these 14s
http://www.pololu.com/catalog/product/1208

These things get hot!


Hi,
I found the 8's get hot but the 11's are fine.

MikeA.

_________________
Smile, it gives your face something to do!

http://www.vimeo.com/user1214873/videos
http://www.youtube.com/user/MrReggub


Mon Apr 29, 2013 1:39 am
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Joined: Thu Feb 14, 2013 12:24 pm
Posts: 284
Post Re: DIY zoom - powered via eMotimo TB3
Woo!
Making progress. Finally got the emotimo, got some supplies, finally made some brackets and did some test wiring.

Got a couple of quick questions for you guys:


1a) Motor noise - is this normal?
I have the purple pololu driver hooked up to the Nema 11 stepper.
http://www.pololu.com/catalog/product/2133
http://www.pololu.com/catalog/product/1205

It's really whiny when enabled. If I set the current limit to the max, the noise goes away, but am I wrecking my motor?
At the max setting it's about 1.2A (see 1b)

1b) Setting the current limit.
For this stepper, it's rated at 0.67A
Should I measure the coil (following the pololu instructions) and set it to 0.469A?

If I do this, the stepper motor won't turn my focus gear.
I have to set it to at least 0.7A to do anything, and it's noisy - at this point it's turning the gear fine.
If I set it to 1.2A (the max) it is silent and works ok. Is this... damaging the motor?
I know next to nothing about stepper motors.
If I use motor sleeping (currently using the "enable" pin) will it make a difference? (since it's being disabled between moves, will the higher amps cause any damage?)

2) Axis settings.
How would I set up my axis in DF anyways - I read the manual but the only thing that really looks like it needs an input is to set it to 200 degrees (full steps) - is that all? (or 400 for 1/2, 800 for 1/4?)

3) Do I need a bigger motor?
I can't get enough torque during microstepping for 1/32 and 1/16
I can get the motor to move when I hit the >> button, but not the > button in dragonframe.
BUT! It works pretty well with 1/4 microstepping. Not sure what the amps are, I just dialed it until it started moving.
Hopefully it's not skipping steps :(

4) Ardpub - where did you get those 40 tooth gears from?



Thank you guys!
Almost there!
Now if only I could get the gears to mesh properly, sheesh.


Tue May 14, 2013 6:18 pm
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Joined: Wed Nov 11, 2009 10:45 am
Posts: 1681
Location: Merritt Island, Florida, Estates Unitas
Post Re: DIY zoom - powered via eMotimo TB3
Sorry if I'm confusing things by adding another option but.....

Direct drive stepper motors are going to suffer from a lack of torque. This much seems to have been proved here. I'm not saying these focus motors don't work great, just that more torque has been something everyone whose built one says they'd like.

Microstepping to get better resolution on the move will diminish your torque even more.

Fortunately there is a different strategy which improves both torque and resolution.

I make focus/zoom motors designed specifically for timelapse photography. They use a right-angle wormgear speed reducer to improve torque and increase resolution at the same time. With a 10:1 gear reduction, I get a 10X increase in step resolution (effectively 10x microstepping) while driving the motor in full steps, which increases its torque over what you'd get by microstepping your driver. In addition, it multiplies the motors mechanical torque by almost 10 times (allowing for small power losses in the gears). When equipped with a 10:1 gear reduction and a little 280 milliamp motor, they produce a lot more torque than any one amp motor I've ever seen. I usually equip these with a 10:1 gear reduction which works well, but since they are built in limited numbers or one-offs, I can offer 5:1 or 20:1 ratios if you would prefer. So... the worm gearbox lets you run full steps (so you don't lose torque to microstepping) while providing the increased resolution you'd get with microstepping. It also further multiplies torque by gearing the motor down. A total win-win situation.

The right angle drive has the additional advantage of getting the motor out of the way by putting it lower, near the rail system. This leaves just the small gearbox up where the direct-drive motor is on your rigs. My motors are enclosed in professional-looking brushed aluminum cases which I manufacture by hand in my garage (a well equipped garage with milling machine and metal lathe to make the parts for the motors). My focus/zoom motors attach to the industry-standard 15mm rail systems just like a regular mechanical follow-focus would. This motor has been successfully used with eMotimo, Dragonframe and Chronos2.

The worm gearbox is a part I buy and pay shipping to me, so it does add to the price of the unit (I have to pay retail for all materials and pay shipping to me because of my small scale operation). There are also a lot of parts for them which I have to make myself. I'm not an industrialist with hundreds of thousands in machinery, I'm just a guy in a shed trying to make something better than what you can go out and buy elsewhere. A lot of time goes into each of the parts which in turn go into the motor. All this costs money even if i pay myself minimum wage or less to do it.

I'll try to post some pictures soon. Until then if you want one, email me at

Sciencelookers@aol.com

Thanks for your support.


Sun Aug 04, 2013 12:22 pm
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Joined: Wed Nov 11, 2009 10:45 am
Posts: 1681
Location: Merritt Island, Florida, Estates Unitas
Post Re: DIY zoom - powered via eMotimo TB3
Here are some pictures of the focus/zoom motors I mentioned in the previous post. The stepper motor/wormgear drive is the third picture (the cute little one). I also show a similar motor with a DC gearmotor which plugs into the Dynamic Perception MX-2 controller and some direct-drive stepper motor brackets similar to the ones you guys have made. I also make one of a kind devices if you want something not shown here. The black endcaps and brackets were all made by me, as are shaft couplers and those nifty aluminum cases. Without automation, each part takes a fair amount of time to make. Its all very 19th-century style with a lot of care and craftsmanship you don't get with mass produced products, but it was the only way I could get the idea into reality. When someone mass produces something as good, I will go away. I understand some people prefer to build themselves even if they have to do it several times and spend more money in the end (its a hobby, I understand), but if you'd rather do the photography and let someone else make the hardware, I'd appreciate the opportunity to make something for you.


Attachments:
File comment: This shows the worm-gear focus/zoom motors for stepper and for the Dynamic Perception MX-2 controller. Also right and left hand brackets for NEMA 14 and NEMA 17 stepper motors without the worm gear reduction
All My Motors.jpg
All My Motors.jpg [ 50.7 KiB | Viewed 2446 times ]
File comment: This is a similar focus/zoom motor which plugs into the Dynamic Perception MX-2 controller
Focus Motor MX-2.jpg
Focus Motor MX-2.jpg [ 39.63 KiB | Viewed 2446 times ]
File comment: This stepper focus/zoom motor fits on industry-standard 15mm rail systems and has worm-gear reduction which increases torque while eliminating the need for microstepping. With the worm gearbox, its 280ma motor produces a lot more torque than one amp motors without gear reduction. The gear reduction also produces an increase in resolution equivalent to 10X microstepping. Its the ultimate win-win situation.
Stepper Focus Motor B.jpg
Stepper Focus Motor B.jpg [ 37.95 KiB | Viewed 2446 times ]
Sun Aug 04, 2013 2:36 pm
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