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Old January 23rd, 2005, 11:46 PM   #1
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Skateboard Dolly

Hey guys,

Today I put together a simple dolly based on the skateboard dolly design i've seen used around here. I measured everything twice and cut once and it came out great. It only has eight wheels though. :-/

It runs pretty smooth but my problem is that i get a few little gitters here and there. They are like micro jitters. I made a small test video of the dolly in action. I don't think you'll be able to see the jitters on the web version but you can see them on the tv version. The dolly runs on 1in sh40 pvc pipe. The wheels are aligned pretty well. They dont seem to be off alignment. Is there anything you guys could suggest I do to take the little jitters out. I tried spraying down the track with lemonpine or whatever and it really didnt seem to help too much. Any ideas??

Heres the Test Clip:
http://www.rch-e.com/temp/dollytest.htm
http://www.rch-e.com/temp/dolly-test.mov <Direct Link

thanks for your help.
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Old January 24th, 2005, 08:26 AM   #2
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I'm going to have a guess here. Was this shot with just the camera
on the dolly and not an/the operator?
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Old January 24th, 2005, 10:06 AM   #3
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correct, just the camera, no operator, is that my problem??
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Old January 24th, 2005, 10:16 AM   #4
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I couldn’t get the video to work, but perhaps you could add some more weight to the dolly. It may smooth out the ride a bit.
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Old January 24th, 2005, 11:11 AM   #5
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add weight to the dolly and make very sure your pvc is straight.

looks nice on the web version though.
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Old January 24th, 2005, 01:39 PM   #6
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im also using 5' pvc lengths and connecting them with 1in dowel rods, that way the pipe is pretty straight in each length, when you get to lengths 10ft and up it starts to become curvy
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Old January 24th, 2005, 04:16 PM   #7
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I'm pretty sure weight (or the lack thereof) is a/the problem. Put
more weight on the system so it is less prone to external issues
(I noticed the speed changes of the dolly as well which is an
indication of a [too] light dolly). Usually the operator rides the
dolly (someone else pushes/pulls)
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Old January 24th, 2005, 07:39 PM   #8
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okay, so i added a 50 lb cement bag to the dolly because i dont have anyone to push me at the moment, since im just testing it, it seemed to help a bit. i've uploaded some photos of my dolly, its a pretty standard design, is it a bad thing that I only have 8 wheels??

http://www.rch-e.com/dollypics/

I also did another small test that can show you the jitters better, they happen right near the beginning of the clip. This test is WITH the cement bag on the dolly. Do I need more wheels or something??

http://www.rch-e.com/temp/dolly-test_2.mov
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Old January 24th, 2005, 08:49 PM   #9
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Why not just extend your pvc so that the jitter happens before the footage you care about? cut out the jitter in post and call it a day.

aside from the initial jitter it looks great right?

I think unless it is massively heavy you are going to experience ramp up and ramp down issues.
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Old January 24th, 2005, 10:06 PM   #10
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Do you have a bolt that fits perfectly in the bearings? Are all of your bearings running smooth? It looks like it's just a subtle shift in position coming from the wheels settling onto the axle as it rolls forward. Either that or a small piece of dirt or imperfection on the wheels or track. Add another 100lbs and try it again. Not a bad rig though, good shot.
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Old January 24th, 2005, 11:28 PM   #11
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darndest thing...i had a washer between the aluminum "sled" and wheel, i took them out and it runs smoother....??? another trick i found is a slight time remap in post
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Old January 25th, 2005, 04:14 AM   #12
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I'm not sure, but I can imagine more wheels might help since they
can spread the load and should be less influenced by imperfections
since there are more of them.

Also how hard are the feels? I'd imagine you don't want too hard
wheels (they look like hard plastic from the photos).
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Old January 25th, 2005, 05:54 AM   #13
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Your single bogie design might be the culprit. I must remark that prior to seeing the design, your original trucking shot looked terrific. My dolly is very similar to yours in that I emplyed the same aluminum vee channel and rollerskate wheels. The difference is that I built 4 separate bogies each with 4 wheels. The platform was 2 half inch pieces of mdf bolted together and weighed about 100 pounds. Worked extremely well but too cumbersome for quick shoots. Gone is my huge platform and now I use an old studio dolly with 3 of the bogies attached. I needed a very quick and portable solution. Works great! 1 1/4" pvc if you can get it gives a little more stability.
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Old January 25th, 2005, 09:20 AM   #14
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I have to agree with Rhett. It looks like the bearings are not set straight, or one of your bolts that serves as the axel might be bent. You might try electrical conduit as track to eliminate any wonkiness that you might be getting from the PVC. Then try getting a new wheel and replace one on the dolly, try it out. If it still wobbles, move on to the next wheel. If you go through all of your wheels, and it still wobbles, start replacing the axel one at a time. If it still wobbles after that, one of the holes you've drilled in the "L" shaped aluminum is probably a tiny bit off.

Bottom line: if it wobbles with no weight, it's best to fix the problem before you throw more weight on. Eventually the weight will make it worse.

Good luck!

Dan
www.DVcameraRigs.com
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Old January 19th, 2007, 10:36 AM   #15
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Skateboard dolly wheels. . . bearings? or Teflon???

Hi all. . .

I'm about to buy a dolly, but am very confused as to whether it is better to buy the Glideshot dolly which uses wheels with ball bearings or the Long Valley dolly which uses Teflon friction "bearings."

In theory, ball bearings should last longer, but a cheap ball bearing isn't inherently smooth. Teflon I would think would suffer from long-term reliability issues, but might be smoother in use since it is essentially flat surface to flat surface.

Has anyone compared these two products? Or is it just a matter of six of one, half-a-dozen of the other?

I like the more professional appearance of the Glideshot GS500, but it is clearly smaller (26 by 30) than the Long Valley (30 by 40).

Any advice would be most appreciated.

Sincerely,

Stephen
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