Submitted by Matt on Wed, 05/19/2010 - 19:26
Posted in
Hi, here's a brief description of my OM project with a sample video.
The Nano Dolly can be retrofitted to a moco dolly using of the shelf NEMA 17 stepper motors . Using the OpenMoco Engine on Arduino basis and a Windows GUI or Perl Skripts, up to 4 axis can be controlled.
The control unit consists of a Pelican 1450 case with an Arduino 2009, L297/298 Motor drivers (lately I used Nanotec SMC11 wit great success). Redundant power supply connector allow to power the unit by battery or power supply (or both). The control software runs on Windows in a Virtual Box on a Macbook pro (lately I use an EEE PC).
All connectors are XLR.
The dolly runs on any standard tracks or pipes that can be fitted with a toothed belt. The track I use has 4 legs that allow to level the track up to 50 cm.
Timelapse tracking from Matthias Uhlig on Vimeo.
http://www.matthias-uhlig.de/?p=609&lang=en
Matthias
Matthias - looks great! I
Matthias - looks great! I especially like the 'rugged case' for the controller/workstation =)
I loved the tracking video the last time I saw it too. It makes me very happy seeing everyone building cool stuff around the engine!
!c
Hey Matthias, This dolly
Hey Matthias,
This dolly looks great! I'm assuming all the framing is from 8020, is that 15 series size?
I have been trying to decide how to build my new moco dolly and I wanted to the track and wheels very similar to yours.
Thanks,
Sean
Sean, it's ITEM, 8020 is
Sean,
it's ITEM, 8020 is hard to get in Germany, so I cant't tell you the exact series, but the framing is made of 40 mm profiles. Which profiles you choose depends a little on what you are trying to achieve.
If you build a dolly like mine, which is also capable of carrying a 100 mm bowl, head and camcorder, I found the heavier the better. But if you are heading out in the woods by yourself with a DSLR for timelapse, get a DP dolly or make something similar. IIRC, the DP dolly is based on a 1030 profile.
Currently I plan on building a new head with ITEM 120x40 profiles and IGUS rotary stages, since my current head is just not ideal for video work (great for timelapse though)
The 40x40 mm are too tiny for even small video camcorders like the Sony Z1 or Panny HVX200. It does work, but very limited in terms of speed (and forget abot macro shots...).
Good luck with your project,
Matthias
Hi Matthias, Just wondering
Hi Matthias,
Just wondering if you can shed any light on how you set up your bearing shafts. I've been looking for a simple sturdy setup that avoid buying price bearing blocks from suppliers. Pics would be awesome.
Best,
Duncan
I did some very simple
I did some very simple bearing shafts/blocks on aluprofiles. Basicly I used a oversized hole through the profile. Big enough so the inner race of the bearing is fre from contact with the profile. Then I made a hole in a strong plastic piece that was a snug fit for the outer race. One on each side of the profile. Using a shaft of quite soft steel that I could thread myself. See image.
The other solution You need a milling machine to do. Basicly the same concept locking it in place with a snug hole and then tighten it in place with a bolt on the threaded shaft. It takes less space.
Duncan, I did the bearing
Duncan,
I did the bearing shaft similar to Ludvig, actually simpler, just holes in the profile. For the pan axis I glued the bearings in. The shafts are 10 mm. I threaded them at the end to tighten them down. Acutally not the bet design, but for DSLR timelapse work it's fine. Just don't start to do video work with it or you will be strongly dissapointed ;-) At least I was. But that's what optical image stabilization is made for (thanks Panasonic, you saved my rear end in this case ;-) )
No, seriously, I wouldn't recommend my design anymore, it was a first try and worked pretty well, but for the next (bigger, better) head, I'll use IGUS rotary stages: http://www.igus.de/wpck/default.aspx?pagenr=3344&C=DE&L=de . Unfortunately, they are not cheap (around 90€/piece)
I probably would refrain from using toothed belts also, since there is always a little play/backlash. If I win the lottery, I'll get harmonic drive gearboxes and servos, but I'll probably have to do it with less expensive units at the cost of more backlash.
That would definitely leave the realms of OpenMoco, I guess.
Matthias
I had a look at the IGUS
I had a look at the IGUS stages. I found the pretty bad. There was a lot of play in all directions. Have you had a look at them? I think Cross Roller Bearing Ring would be a better choice. And cheaper too. http://www.thk.com/us/products/class/crossroller_r/index.html. I dont have any prices on the RU series wich seems like the perfect fit. But search Amazon.com "THK Cross Roller Bearing"
Best regards
Thanks for all the info and
Thanks for all the info and the 3d mockups. Right after I posted I gave it some thought and came to the same design realization. I've got scads of 8020 profile around and access to a laser cutter so I'm going to whip up some of these diy bearing blocks out of .25" inch plexi and see how well they hold and how much play I get. I was also looking at the igus rotary stages a few months back, and I tried my best to get them to send me a sample but no love.
The roller bearings look interesting btw, I'll have to do a little digging.