Submitted by threeaxis on Mon, 04/12/2010 - 18:24
Posted in
The Klunker: Or how not to build a pan tilt. ; )
Frame Design:
The frame is built out of 80/20, all purchased out of their ebay store. I had no idea this stuff was so HEAVY!!! ... would have gone with 10 series or something tubular like the mr. moco UltiHead on a smaller scale had I known just how heavy the 8020 aluminum was. The adapter plates were all made with a drill press with 8020 flat pieces.
Worm Gears:
Ok so I purchased a couple of optical rotary tables from a chinese company bjwn.cn/En/ProductDetails.asp?ArticleID=49 they run about $400 each (less if you know anyone in China), by far the cheapest motorized rotary table I could find on the internet. However, they've proven not to be suited for this type of work and the constuction was suspect. I thought they would be great since they are rated to hold 66lbs vertically... which translated to way less than 10lbs horizontally. I had a small object mounted and about 4 lbs. of aluminum on one, and it was mounted to a studio stand... As it was turning it popped out of alignment and I've yet to get it aligned properly to where it would not slip. On top of that the taps were all sorts of crooked (see pic).
It also has a good amount of play that is visible in the high-res version of the test vid. I thought it was from the frame but after locking everything down I finally realized it was coming from the rotator assembly... Every time a gust of wind hits you can see it.
I've talked to the company and they will realign it if I send it back to china but seeing how shipping to china was not the cheapest I'm thinking I'll just chalk it up as a learning experience and wait for shutterdrone and milapse to finish up thier models and find another use for these.
Anyhow, here's some pics of the pan-tilt before it broke (about 2 weeks of use). I got the one test vid and a few hours in the studio before it popped... So, it was a pricey experiment ; ) I'll post an update if I can get the thing re-aligned.
Excuse some of the crud phone pics.
The wonky taps:
Downtown NYC Timelapse Test
http://www.vimeo.com/10853062
Wow this is scary, not only
Wow this is scary, not only does my design look more or less exactly like yours. I have been surfing optical rotary tables all weekend! I have found a few that seems rather good. More in the region of 1000-1500$ without motor/controller, low-zero backlash and 30:1-90:1 gears, rated at 25lbs and up vertically. One of many velmex also looking at ebay of course.It is still a lot cheaper than a mrmoco head. I am mostly aiming for realtime and will probably use Gerards software http://bfg-motion.com/index.php?p=1_4
I figure that if I buy quality rotary stages and strong decent quality motors whatever I put around them in prototyping doesnt matter too much so I think I will still go for the 8020 approach. What would you have done in my shoes? Have you managed to source any modular stuff similar to ultihead in 8020 pricerange?
I am leaning towards the design of sfh-50 http://www.mrmoco.com/Products/Heads/_MG_8623.JPG
Any opinions from people is very appreciated!!
Ludvig
Ludvig, Out of curiosity, how
Ludvig, Out of curiosity, how much does a Mr. Moco head go for? I thought it was around 10K+?
Yea looks like we've dug around the same places. ;) ... and I'm also looking to do realtime in long run.
I was taking the rotary stage route as a hopefully cheap alternative to sherlines but while also looking to hold a decent amount of weight, which didn't quite work out for me.
Would love to see which rotarys are your picks other than the Valmex. Newmark and Parker were the ones I kept running into. NOT cheap but probably very well made.
As for the cine rails / tubes / rods... I didn't find a source for the angled brackets but figured it was easy enough to build with just a drill press... and all the other sliding "mounts" are already on the market.
As for going with a design like sfh-50... I'd love to see how you would translate that into 8020?
Cheers!
I think the "low cost"
I think the "low cost" stepper version of sfh-30 is around 8000 usd, that is without any controllers or software. Sfh-50 is more maybe 12000? The servo versions are again more expensive.
I found LOTS of different rotary stages manufactors I dont know prices of most products though...
aerotech
zaber
lintechmotion
dovermotion
intellidrives
physikinstrumente
primatics
techno-isel
useurotek
Regarding the 8020 it is more as a prototype right now. To figure out motors, gearing etc.
Maybe I will go for flatter alu than standard cubic 8020 like 15X75 mm
http://www.techno-isel.com/lmc/Products/TablePlates1575.htm
Very cool Ludvig! Thanks for
Very cool Ludvig! Thanks for the price info. Yea in the 80/20 catalog they have weight ratings on all the different materials / with connectors. I based my 80/20 on that, which was overkill... I now that I know this stuff is pretty strong seems like flatter alu would do the trick just fine. Can't wait to see what you cook up!