DIY (Do-It-Yourself) Dolly and Track System

Transcription

1 DIY (Do-It-Yourself) Dolly and Track System One of my tools for production is a dolly and track system I built from scratch. The design was inspired by a design by Hollywood Cinematographer and Director Ron Dexter. A dolly holds a tripod and either runs on the floor or runs on track. The track dolly has the advantage of all-terrain use. A nontrack dolly needs very smooth ground to insure vibrations aren't introduced into the camera's image (camera instability). By using a track, you can create a smooth running surface, such as in a gravel road, thereby allowing the filmmaker to accomplish nice tracking shots in all terrain. Another flaw of many commercial dollies, such as the popular D-10 model shown here by Velbon, is that they use casters as wheels. This means that if you wish to do a track to the left, followed by a track to the right, the wheels usually catch as the change direction. Anyone that's ever used a grocery store's shopping cart and moved it forward and then backward knows what this issue is. The next sections will describe how I constructed my track and dolly system. If you choose to build any thing you have seen on this site, be sure to take all necessary safety precautions including the use of safety glasses. Light-Duty PVC Track-Based Dolly Medium-Duty Metal Track-Based Dolly Dolly Track System 1

2 Light-Duty PVC Track-Based Dolly Main Dolly Page This dolly is designed for light-weight cameras and tripods only, and because you must walk behind it, it is mostly only useful for cameras with a flip-out LCD. This was my original dolly design, and I didn't keep detailed photographs or notes. For more construction details for this dolly design, see the Ron Dexter's tutorial which inspired this design. I'll only discuss here the things I did differently. Please note that this particular track dolly design does not permit the cameraman to stand on it, nor will it support a heavy camera system (such as a crane). The means to create a more solid track dolly are self-evident from this tutorial. Here is the basic dolly, built out of 1/2" Schedule 80 Dark Gray PVC Pipe: Be sure to use Schedule 80 with an inner diameter of at least 1/2". The Schedule 40 (the most common PVC available) is too flimsy and will warp easily. Some states in the US do not require Schedule 80 in their building codes, so you may not be able to find it, in which case, I recommend you build a metal dolly instead. If you live in California however, you can easily find it. (Note: "Schedule" refers to the gauge or thickness of a material. Also note: all diameters given for PVC components are always by inner diameter.) The dolly has a thread-less Tee-fitting at the central joint and holds each of the arms of the dolly with a bolt 2

3 and wing nut for each arm. The arm's length is determined by the tripod used, and so careful measurement is required before one starts hacksawing their raw PVC pipe. Each arm's end has a threaded Tee-fitting with its one end pointing upward. As you can see in the next picture (showing the dolly holding a leg of the tripod), a 45º thread-less angle with an inner diameter of 3/4" fits snugly onto the outer rim of the 1/2" Tee. The friction alone should be sufficient to hold the tripod in place. For the arm shown above only: after the Tee used to hold up the tripod leg, the next piece along each arm is a 1/2" female-to-female adapter (in other words, this little adapter has a male threaded end on each side). Then there is another Tee, with each end having a flat 1/2" threaded plug at the end. For the other two arms: after the Tee used to hold up the tripod leg, the next piece is a flat 1/2" threaded plug at the end. The following applies to all three arms: a bolt is then locked with a lock nut through a hole centered in the 1/2" threaded flat plug, and continues on to a square block of wood. Each block of wood has had a section removed to allow for the bolts that are sticking out of the angle iron. The angle iron has been screwed into the blocks using wood screws. The skateboard wheels, which have two ABEC-5 bearings each and a bearing spacer, are bolted through the bearings into the angle iron (the angle iron comes with a 90º bend in it) with a 5/16"-18 (Coarse Thread) bolt of 2" in length and nylon-insert lock nut. The bolt head is a hex head and, as is obvious from the picture, the head is on the outside of the wheel. Due to the width of the wheels and the angle at which both wheels are to each other, the wheels can actually accommodate a range of sizes of track. Mine accepts a track from 1/2" to 2". The 1/2" track you see here was just something used during testing. A separate section explains the construction of a heavy duty track system. 3

4 The total cost to build this dolly was approximately $75. Most of the expense is in the wheels and bearings. The wheels were $18 for four, or $36 for all eight. Be sure to get the poly-urethane wheels (they are softer and run smoother and quieter), and don't waste your money on designer wheels. For the ABEC-5 bearings (or you can get ABEC-7, but don't get ABEC-3), buy them where they sell bearings for inline skates and you'll get a pack of 16 bearings (the number you require). Mine were about $20. Be sure your bearings are the same size as the wells for the bearings in the wheels. Also, be sure that when you put the bearings in, you have them ALL the way in (they go in deep). If you buy them at a sporting good or skateboard shop, they can put them in for you, otherwise you can use the largest socket of a wrench and socket set that will fit to force them in. Finally, bearing spacers are optional but a good idea to get considering they are only a few dollars (they go between the two bearings of the wheel and thus are sitting in the very center of the wheel). If you construct a heavier duty version of this dolly, the wheel assembly of this design is sufficient for a much heavier load, so you shouldn't need to change that. Only the arms and support would need to be changed. Be sure to construct with as little glossy metal as possible, since shiny surfaces reflect lighting used in filmmaking, often producing negative results. Hence most photography and cinematography equipment is black. Finally, use nylon-insert lock nuts whenever possible. These usually require a good socket wrench to put on, but the advantage is they need a socket wrench to get off as well. In other words, they won't work themselves loose over time. 4

5 Medium-Duty Metal Track-Based Dolly Main Dolly Page This section describes how to build a medium-duty metal dolly that will run along a track. It is designed to handle heavy cameras and tripods, but the cameraman must walk behind the dolly when moving. This makes it useful for digital video cameras with a flip-out screen, but may be difficult to use with a film camera when the cameraman has to keep their eye glued to the eye piece. After working on a 16mm film, I quickly discovered a need to redesign my original PVC dolly to accommodate the heavier film cameras and tripods. During this redesign, I kept more detailed snapshots. Construction of the track is explained in another section. 5

6 The main components in this dolly design are 4 metal Tees and 4 metal 90º bends (found in or near the lumber section of a hardware store), and two 3' slotted L-shaped metal bars (found in metal working section). I cut the metal bar that appears vertical in this picture to make the short section of metal bar you see at the bottom of the Tee. All of this costs around $20-$30. I assembled the vertical part of the dolly (the portion that appears vertical in the picture above) as follows. First, this is the piece that is shorter. The 6

7 L bar is 36" long (3'), and I cut off 6" of it with a hacksaw to make the wheel structure for this odd end of the dolly. I also shortened two of the 90º angles so they could fit on the 6" L bar and yet not overlap. Be sure to still allow two places to bolt onto the L bar (in other words, only remove what you must from the angles to fit them on the 6" L bar). I removed about 2" from each of the two angles, on just one of their sides. I recommend using a Mitre box for all hacksaw work (and hand drilling for that matter). 7

8 For added rigidity and structure, I drilled a second hole in each of the Tee braces (so there would be two bolts to secure it versus one along this direction of the structure). I strongly recommend this step. I used two Tee braces sandwiched around the slotted metal L bar. I did this for both end of the L bar I had cut, and then attached the short cut-off piece of the L bar to one end. I then attached the two 90º angle bends I had cut down (again, so that they wouldn't overlap on the short 6" L bar end). 8

9 I bolted this and every component of the metal dolly structure with 1/4" 20-thread (Coarse Thread) 7/8" long bolts, a 1/4" hole 1-1/4" diameter fender washers on both sides of any given hole in the L bar or Tee brace, and 1/4" 20-thread (Coarse Thread) nylon-insert lock nuts. In other words, through any given hole, there is a bolt head, then a fender washer, then it travels through the hole, then another fender washer then a lock nut. Here's the completed "vertical" section of the dolly: 9

10 I then attached the two un-cut 90º angles onto the un-cut 3" L bar, again always using two bolts for any given structure to insure rigidity: I then took the same wheel components from the original PVC design (after spray-painting the wood to be flat black). Each block of wood has had a section removed to allow for the bolts that are sticking out of the angle iron. The angle iron has been screwed into the blocks using wood screws. The skateboard wheels, which have two ABEC-5 bearings each and a bearing spacer, are bolted through the 10

11 bearings into the angle iron (the angle iron comes with a 90º bend in it) with a 5/16"-18 (Coarse Thread) bolt of 2" in length and nylon-insert lock nut. The bolt head is a hex head and, as is obvious from the picture, the head is on the outside of the wheel. Due to the width of the wheels and the angle at which both wheels are to each other, the wheels can actually accommodate a range of sizes of track. This designs accepts a track from 1/2" to 2". 11

12 A bolt is locked with a lock nut through a hole in the angle bend that I had to widen to accommodate the bolt (using a drill), and continues on to a square block of wood. I used a 5/16"-18 (Coarse Thread) bolt of 2-1/2" length to attach each wheel block to the 90º angle bend, with the bolt head on the outside and the nylon-insert lock nut and fender washer on the inside. However, no matter how tight I made this bolt, the whole wheel block could still rotate. Fortunately, I didn't cut the excess end of the 90º angle bend, so I used one of the other existing hole in the bend to put a wood screw through to prevent the wheel block from rotating. 12

13 Here is a close-up of the short 6" end's wheel assembly: Follow the same steps for the longer end of the dolly. Then attach the shorter end to the longer end using two 1/4" bolts and wing nuts (allowing it to be disassembled). Note the wing nuts are on the part of the Tee brace sandwich (which sandwiches the L bar) that attaches to the longer un-cut L bar. This is because you have more ability to insure alignment this way due to the back wall of the un-cut L bar acting as a backstop when assembling your dolly on location. 13

14 I found some small end braces in the wood work section of the hardware store that I attached with wing nuts onto the dolly to hold the legs of my tripod. The wing nuts are nice because I can always move them on location to adjust for various tripods. 14

15 I found some springs to help hold the tripod legs into place. They aren't terribly secure, but the weight of the tripod and camera fixes that. You can also use a durable twine or cord to tie the tripod feet in tight (and I carry twine just for this purpose while on location). 15

16 And finally you can spray paint the metal with a flat black. Use primer first! (Otherwise your paint will flake off the metal easily.) Don't paint your nylon-insert nuts at all (mask them off or remove them), and don't paint your wheel assemblies (except the block of wood) to insure the paint doesn't eat at the non-metal components (which can happen). 16

17 The next section explains the construction of a heavy duty track system. The total cost to build this dolly was approximately $100. Most of the expense is in the wheels and bearings. The wheels were $18 for four, or $36 for all eight. Be sure to get the poly-urethane wheels (they are softer and run smoother and quieter), and don't waste your money on designer wheels. For the ABEC-5 bearings (or you can get ABEC-7, but don't get 17

18 ABEC-3), buy them where they sell bearings for inline skates and you'll get a pack of 16 bearings (the number you require). Mine were about $20. Be sure your bearings are the same size as the wells for the bearings in the wheels. Also, be sure that when you put the bearings in, you have them ALL the way in (they go in deep). If you buy them at a sporting good or skateboard shop, they can put them in for you, otherwise you can use the largest socket of a wrench and socket set that will fit to force them in. Finally, bearing spacers are optional but a good idea to get considering they are only a few dollars (they go between the two bearings of the wheel and thus are sitting in the very center of the wheel). Be sure to construct with as little glossy metal as possible, since shiny surfaces reflect lighting used in filmmaking, often producing negative results. Hence most photography and cinematography equipment is black. 18

19 Finally, use nylon-insert lock nuts whenever possible. These usually require a good socket wrench to put on, but the advantage is they need a socket wrench to get off as well. In other words, they won't work themselves loose over time. Here's a picture of this dolly being used by my friend, Kevin Brunkhardt, for one of my previous films, A Matter of National Security: 19

20 Dolly Track System Main Dolly Page This track system can handle an extreme amount of weight and so is very heavy-duty. While my original PVC dolly was inspired by Ron Dexter's tutorial, the track system is completely my invention. (Unfortunately, there's nothing patentable about it though, as it really is just common handrail laying on the ground.) I spent a lot of time trying to devise a good track system, and now that I have, I'll explain it in as much details as possible. I bought 1-1/2" Schedule 40 Aluminum Pipe. If you want to save money, you can use steel. Aluminum is about 3 times the cost of steel, but is also 3 times less heavy. Additionally, steel is a lot harder, making this whole process a real pain. Have fun drilling through steel without a drill press! Although I recommend a drill press in any case, if you don't have one but 20

21 are very careful, you can still line up the holes just right. (I didn't have one and am very impressed with the quality of my track.) The best price on raw aluminum pipe is from a metal supply company. In Los Angeles, the best choice is Industrial Metal Supply (IMS). Whoever you go to, they sell it by the 20-foot pipe. (If they sell smaller pieces, they're probably also charging more.) As of March 2003, IMS in Irvine, CA, was charging $3.49 per foot as long as you bought whole 20-foot pipes. They had an additional charge to cut the pipes. I bought two 20- foot pipes and had them cut into 5-foot long sections (and so ended up with a total of 8 5-foot long Aluminum pipes). You definitely don't want to cut these pipes yourself unless you have the capability to cut very clean and straight (that is, have access to an industrial metal saw)-- descent precision is important on these cuts. The total cost for this raw material was about $165 after tax. 21

22 So now I had 40 feet of Aluminum pipe, cut into 8 pieces of equal length. The reason to get them cut, if you haven't figured it out, is to simplify transporting them. After all, the primary use for something like this is to take it on location filming. So the next step is how to rejoin the sections into long track. I picked 1-1/2" Schedule 40 Pipe for a reason: this is the standard size pipe used for handrails and the like. A company called Hollaender makes a ton of different joints for 1-1/2" pipes and some of their components go by the brand-name SpeedRail. By the way, I'm not the first person to think about using SpeedRail for entertainment. The particular piece of interest from Hollaender is their 1-1/2" No. 70ES Internal Locking Splice (Note: on internal fittings, the 1-1/2" is the outer diameter, which corresponds to the inner diameter of the pipe it will fit in.) Hollaender is a manufacturing company without a store-front and doesn't sell a few pieces at a time to consumers. While Industrial Metal Supply can order 22

23 them for a fee, the best place I found that had them in stock (or would order them at no extra fee) is Budget Fence. So, with 8 sections of pipe, 4 sections to make up a 20-foot run of track on one side of the dolly, and 4 sections to make up the other side of the track, I order the required 6 internal locking splices. With shipping, the total cost was about $45. You may need to supply your own Allen wrench, but here's what you get: The No. 70ES Internal Locking Splice works by forcing the set screws into the opposite wall. As you tighten the screws, they push against the 23

24 opposite wall, forcing open the splice further, thereby growing tighter against the wall of the pipe you set it in: The next step is to start making careful measurements on your aluminum pipe and tapping where you'll drill to make the hole that allows access to the set screw. Note there is just one hole for each end of your aluminum pipe that you will drill. Make the measurements such that the pipe will join the next piece of pipe perfectly in the center of the length of the locking splice. A smooth interface without any gap is critical to insure the 24

25 dolly won't sense a bump when it travels over sections when you perform a tracking shot. The hole size is a 3/8" hole that allows the access to where you put the set screws in the internal locking splice. Drill the holes and install the splices. (Note you cannot put the splice into the pipe with the set screws on. Take the set screws out then slide the splice in.) Also, be sure to have all the holes for your pipes on the same side. That is, with your pipe you'll have a total of two holes in it, one at each end of the pipe. Make sure both of these holes are on the same side of the pipe 25

26 and as close to lined up as possible, though if they are not there is no impact on the stability of the camera. The impact that it would have is if you decide to create crossbeams for the sections of the track, since such crossbeams will most likely bolt through the pipe and into the locking splice. I chose not to make crossbeams, and instead feel that for my use I can just duck-tape the ends of my connected 20-foot length of track into position. Crossbeams only add structural support. They don't dictate the smoothness or stability of a tracking shot. As long as you have both sides of track reasonably parallel, the act of tracking with your dolly will force the two sides of the unconnected track into a true parallel position. In fact, practicing a track before filming is advisable to insure the track is aligned, then consider duck-taping the ends before recording. 26

27 So, with all of the 3/8" holes drilled and the splices installed, begin tightening the set screws as tight as possible using a 3/16" Allen wrench: The final product of the joint: 27

28 If you do all of this right, you'll end up with an extremely smooth track and dolly system. Also, make sure to bring your allen wrench with you on location!!! 28