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Old June 10th, 2004, 02:08 PM   #1
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Building a Better Homemade Dolly...

I'm determined to start building my own dolly here pretty soon. I believe I'm going to use the designs commonly found at HomeBuiltStabilizers that utilize skateboard wheels and pvc pipe, but before I commit to this particular designs, I wanted to discuss some of the specifications of these dolly systems with those of you who have experience with them in order to get a better idea of what to do and what not to do.

In particular, on most of the designs I've seen that use skateboard wheels...I've noticed that nearly all of them seem to be just regular old skateboard wheels, hard ones. Now, I don't know how much knowledge you guys have in the skateboarding department, so perhaps I might be able to enlighten even just a few of you in hopes of making better homemade dollies.

Some friends of mine that skate told me that instead of going with plain old hard wheels, that I should instead look at using much softer wheels. They said that companies make some pretty soft wheels specifically for people who make skate videos and need a smooth ride on their board. They're not super super soft, but they definitely use a much softer rubber than the wheels that I've seen most people use. Naturally, they cost just a tad bit extra. But I'm hoping it will be worth it.

The reason I'm thinking about using these softer wheels is because I've heard some people say that these amateur pvc pipe dollies don't give the smoothest of rides, while at the same time I've seen other people say they ride plenty smooth. So I guess I'm just hoping for some reinforcement behind this idea from any of you guys who might know what I'm talking about...if it is an area that could be improved upon.

Also, if you guys have any other suggestions about ways to improve upon these dolly designs, it would be greatly appreciated. One thing I'm curious to know about is if that Lemon Pledge idea on the Long Valley Equipment site actually works. The part where they say that coating the pvc pipes with Lemon Pledge repels dirt, and most importantly, makes the dolly silent. Can any of you confirm this?
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Old June 10th, 2004, 03:41 PM   #2
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Lemon Pledge is a standard item to be found in a dolly grip's kit. I will confirm that it is in use on big budget movies.
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Old June 10th, 2004, 05:10 PM   #3
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Welcome to the forum Frank! I'm currently in the throws of home-made dolly design and I'm kicking a few ideas around.

The softness of skateboard and inline skate wheels is called "durometer". Most of us should be familiar with the word from the rubber used in shockmounts. Manufacturers mention "special durometers" but they rarely state what it is.

So for about the softest skate wheels you'd be looking at 78a and hard ones may be over 90a... That should give you guys an idea of what to look for.

Recently I've purchased several types of inline and skate wheels and often the special deals don't say what the durometer is... so I just bought some to find out.

I have a plethora of inline wheels all at 78a. My dolly idea for those would be to use 2 or more pairs of wheels at each corner of the dolly, with the wheels mounted vertically, just like on skates... as opposed to the 45 degree angle that's popular with the skateboard wheels... either way you're side-loading the bearings, but with the limited use that any dolly will see I don't see wear as a big problem. If you imagine two inline wheels about .25 to .5" apart you can see how they would ride a pipe.

The other factor of a dolly is the bearings and about the best COMMON rated bearing is "abec 7"...

Abec is the "association" that rates bearings and the 7 refers to the smoothness (and number of bearings inside)... There are ratings beyond 7 but most are the less precise "abec 5"... Just a thought.

It would seem that Baltic Birch is the best material to use for a platform, but I was bummed when I bought a sheet and it warped before I could put it to use! I went with 3/4" but I'll bet the 1/2" would work... This crap is HEAVY!

I think I can logically tell how the Longvalley track connectors work... I don't think there's much to them... I'll report back when I get that figured out.

About the only thing I'm still wavering on is whether or not I should make the wheel assemblies swivel... So far I don't imagine using curves with dolly shots, but maybe I'd be missing out. Are curves with dolly shots difficult?

My initial ideas include a fixed dolly that only goes straight 'cause I imagine it to be difficult to get perfect dolly action AND run a curve at the same time... What do you guys think?

As far as the Lemon Pledge I can see the point of it easily... With my first dolly design that used the inline wheels I was surprised that they could mysteriously "find" traction every now and move the pipe or the dolly or make some sound... or all three.

Rather then call it Lemon Pledge I'm going to offer some alternatives:

1) dolly juice
2) production lube
3) track wax
4) gaffer's gravy
5) lemon grip jelly
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Old June 10th, 2004, 06:01 PM   #4
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I built the dolly I used on my LadyX film, based on the shadowgirlproject site.


I used softer skate wheels, and "standard" bearings. I do not know the specific durometer or grade of bearings but I can try and look for it when I next see my dolly.

Iused 1/2 inch plywood for the floor, and framed on top of that with 1x2. This gave the legs something to hit against and not slide off the dolly top.

I used PVC pipe, straight for my track.

Overall I was VERY pleased with the results. If you look at my Episode (#26) from the site, the final scene is a party scene and we use it there the most. I thought it did pretty damned well.


Matt, and others, If I were you I'd try and put swivelling wheels on as that will give you more flexibility. When I did mine, I didn't want to risk buggering it up and wasting all that $$ and I only needed straight track so it wasn't necessary.

Another thing I'd look at if I made another one, and that would be do place a column in the middle and put a mounting plate on it that could swivel. Of course an operator chair that could swivel about the column is necessary too. This would mean you could make some much cooler shots, although you can attempt them without a column just by walking around the dolly and panning. Also, if you place a column on it it's going to get a lot heavier.

Another thing I've seen someone do, is build a small dolly that rides on an aluminium ladder. There are 2 wheels in each corner, one facing down to ride on and one facing in as guide wheels. Light and easy to setup track (Can be used as a ladder too ;) ).


Aaron

BTW: My dolly has been sitting outside at someone's place for the last few months, so I'm going to get it this weekend and see if it's totalyl warped and crap now.
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Old June 10th, 2004, 06:37 PM   #5
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The dolly I use was home built and uses the basic 90 degree angle aluminum bogies mounted at each corner with four wheels per bogie for a total of 16 wheels incontact with the inch and a quarter pvc pipe precisely set apart by rail ties.
Before you look to M.I.T. for more finite specs on your wheels and bearings you might want to consider that the key to this thing is a straight track and a heavy platform. I used two peices of mdf held together by speed nuts that provide a smooth blind hole. It weighs about 95 pounds. Any minor deflections caused by the track are ironed out under the weight of the dolly.
Total cost to build was about 50 bucks.
The nice lady at the roller rink tossed in the used skate wheels for free. Yep - used. So long as they are round, a heavy platform will keep you smooth.
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Old June 10th, 2004, 06:44 PM   #6
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That is a good point. Weight is good in some respects. My dolly was quite heavy and this helped to straighten the tracks. Chuck the dolly on the tracks, get someone to stand on it for extra weight if needed and then move it along the length a few times. The pipe will adjust.

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Old June 10th, 2004, 07:06 PM   #7
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True for flat surfaces ... no need to bother with the track ties, but what a great equalizer when dealing with a gravel driveway, over a threshold between rooms or on a smooth concrete surface that might have the odd pebble... and you can shoot solo if needed.

I find the ties extemely useful...
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Old June 10th, 2004, 07:20 PM   #8
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I really appreciate your responses guys...

Yeah another thing I wanted to discuss was curved tracks. I haven't really worked out how to go about accomplishing it. Naturally, I would prefer the dolly that I build be able to run smoothly along both straight AND curved tracks, so according to what you guys (Jimmy and Aaron) are saying about having a really heavy platform, I should probably look for something a little lighter, eh?

I've been thinking about the different possibilities of what exactly I should have my tripod sitting on. If I can't find a full platform that will be light enough and strong enough for what I need, I might just try using a T-shaped frame and just have each of the tripod legs rest on the three corners. I'd also set up the wheel assemblies underneath in the three corners of the T, with two assemblies dedicated to one of the rails and a lone assembly dedicated to the other rail. I believe there are some examples of these designs over at HomeBuiltStablizers.

It all depends though, I'm just not sure if I'll be able to build a dolly that works effectively for both straight and curved tracks, or if I just just give up that idea and go with the heavy platform/straight track only design. I really like that swiveling wheel assembly idea that Matt has. That just might do the trick.

By the way Aaron, I also like your idea of adding a little frame on top of the platform to secure the legs of the tripod. I have been having trouble figure out a simple way to do so, but now that problem's solved. On a side note, I tried watching your LadyX episode to see footage of your dolly in action, but for some reason it cuts off around the 4:30 mark. Damn shame. Would've like to see that.

And smart move in going to the roller rink, Jimmy. Looks like I'll be making a stop by my local rink here shortly. What do they normally do with the used wheels? Just throw them out?

EDIT: About them ties, what exactly do you use for them again?
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Old June 10th, 2004, 07:44 PM   #9
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Gents:

For what it's worth: in my experience, I would say I have worked on straight track 95% of the time. Most of the time that curve tracks works is for doing a 360 or partial circling in which case you need quite a few sections and it's extraordinarily challenging to get the track leveled to match at the ends.

Now, I should point out that most of the compound moves that you see in movies, TV etc. are done either on a smooth enough floor to dolly directly, or on dance floor (high grade birch or plastic laid on top of 4x8" plywood). Once the move is designed, the grips build a dance floor as needed and the dolly can now move smoothly in any direction. We almost always work in crab mode, meaning the wheels all turn together so the chassis itself doesn't turn.

The reason for this, and the tricky part with curved track (especially if a length is added on to straight track), is that as an operator it's a pain to have to backpan when the chassis is turning relative to the action. In other words, you want to keep the lens pointed straight ahead, but the dolly is rotating which forces you to have to pan at a specific rate just to keep the frame where it is. If not done exactly, the frame will appear to "wander" side to side. Without a really good fluid head, it's very difficult to avoid this (I won't even go into what's involved in doing this on a geared head!)

So the moral of the story is: try to work on straight track whenever possible, I guess. Others may have a totally different recommendation!

p.s. that said, I do own a Losmandy dolly with the Flextrak for DV use, which of course allows you to effortless lay down a compound curved path. I find that I end up spending a lot of time trying to make it perfectly straight, however!
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Old June 10th, 2004, 08:00 PM   #10
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Ahh Charles, to have a pro give his realworld advice rather than our half arsed observations ;)

I mean it though - that was very interesting to hear that straight is used most of the time, and when curves are done they use a dolly on the floor. I honestly would have thought they'd use curved track. If your observations are a good sample of the industry then those dolly grips must be damned good at their jobs!

Frank, as well as keeping the tripod on the dolly, a frame also helps in stoping the dolly warping. Hmm, I just had a thought. If I made my next dolly I would make the frames removable in their own sections so that if needed the camera op could kneel, hanging off the side without having her shins have to go over the frame. This is what happened in our film, so it was a bit uncomfortable for her for low shots.

Also, right click and "Save as" the movie. I just tried it and that worked. Just skip to the final scene, the rest aint that good :)

Jim, I'm interested in what you used for ties too as that sounds like a great idea.

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Old June 10th, 2004, 09:08 PM   #11
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Aaron, there are a bunch of great dolly grips out there (and quite a few of not so great, but that's true of all of our jobs). The best of them are almost operators in their own right; they understand what needs to happen as soon as the shot is described to them and anticipate changes (you never build a dance floor to the exact size you need, so you can tweak the shot a bit later on). During the shot, they make subtle adjustments in the move if the actors don't hit their marks, listen to dialogue for their cues, etc. And when the director or DP asks for "go 20% slower on the push in" they can dial that in like a machine!
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Old June 10th, 2004, 11:21 PM   #12
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Charles, I really appreciate having your input on this issue. I agree that we're lucky to have REAL professionals as members of this board... I'll bet when Chris started this thing he didn't realize what a snowball of information it would become...

Your comments cinched it. I imagined a lot of difficulty in shooting curved dolly shots and you gave me the tiny nudge I needed to continue in the fixed direction I was heading.

I've always tried to subscribe to the KISS principle and I just think a rock-solid straight only dolly would yield superior footage...

As far as the ladder idea... I stared into space in the ladder aisle of Lowe's for about an hour. All I could think was, "this is perfectly aligned and super lightweight dolly track"... So what do you guys think? The main reason I abandoned that idea is the complexity of going beyond one length. Considering an 8' ladder is only $49 at Lowe's the cost isn't an issue... the limited distance is...

The lowest possible cost I've found for wheels and bearings ends up being $2.01 per inline wheel with a pair of abec 7 bearings OR $2.34 per skateboard wheel with a pair of abec 7s. So for a dolly design with 16 inline wheels you're looking at $32.16 for wheels/bearings... and a design using 16 skateboard wheels is $37.44. This is JUST for wheels/bearings.

After that I've seen angle iron used to mount the skateboard wheels at a 90 to each other... and again the platform is up to you. The swivel idea isn't mine... Longvalley offers dollies that will follow curves...

I've been hesitant to give away another dolly idea I've been working on... but just think of the sky-cam that they use on cables in the NFL... Cable dolly anyone? I'll post footage when I get the kinks worked out of it. Originally I wasn't going to tell ANYBODY about this one, but it's been so hard to get it to work right that I don't think I'll have a problem with other videographers competing with me locally.
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Old June 11th, 2004, 01:35 AM   #13
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I wouldn't worry about being secretive about an overhead cable system Matt...I just saw an amazing screening of the 1927 classic silent film "Sunrise" last night (restored print and accompanied by a live orchestra--wow!). They used just such a rig for some dolly shots in that picture. Yup, 75+ years ago. Like I said, no worries!

I got to operate the original Skycam (the one in use at the NFL is essentially a ripoff) at the '96 Olympics in Atlanta. It was a LOT of fun, like a cross between flying an utterly high-tech RC airplane and a real-life video game. Check out my man Garrett Brown's website for demos of the Skycam and all of his amazing contraptions, including a little thing called a Steadicam...! And don't miss the latest addition, the Molecam.
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Old June 11th, 2004, 04:34 AM   #14
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Wouldn't it be more easy if you have curved stuff happened when
they "free" the dolly and put in a dance floor to simply use a
steadicam, Charles?
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Old June 11th, 2004, 11:47 AM   #15
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Rob, the decision to use Steadicam or dolly is based on many factors. Some directors or DP's like to use Steadicam as much as possible; others, as least as necessary. I actually fall into the latter category when directing or shooting, believe it or not! One issue with Steadicam is that the operator cannot give feedback on focus; it's up to the assistant to "feel" whether or not they nailed the shot, which can be dicey on a longer lens/close to subject/or wide-open aperture. Steadicam has a different feel than dolly. If the shot involves some movement but long lockoffs, or very slow movement, it will certainly play differently on the dolly. Also, it may involve more height changes than can be accomodated with Steadicam (around 3 feet of vertical travel vs 5-6 feet with the arm of the dolly).

Sometimes the combination of the two is the key. I have many times "hardmounted" the Steadicam arm to the dolly for slow-moving or long-holding shots that had to be performed on less-than smooth floors, for one reason or another. The Steadicam takes out the bumps, leaving behind a classic dolly shot. The most famous (and first) example of this is the sequence following the little boy on the Big Wheel through the hotel in "The Shining" (and others in that film as well)

I did one in "Office Space" when the Two Bobs are interviewing Lumbergh in the conference room; there's a shot that starts with a wide profile of the three of them and dollies around inbetween the Bobs looking to Lumbergh. Not an exciting shot by any means, but the proximity of the conference room wall behind the Bobs eliminated the possibility of the dolly being able to get far enough back with a conventional camera mounted on it. However, it was critical for the shot to not have a "presence" to it, it needed to be virtually mechanical and Kubrickian in its accuracy, so body-mounting wasn't the solution. The result is an undetectable dolly shot, made physically possible with the Steadicam.
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