This is how I built my time lapse dolly, it was made with a whole bunch of trial and error, hopefully this will help you build yours.
A lot of the stuff I used I had on hand, don't know where I got it, or have no idea what it worth but I'll do my best at giving you a complete list of what I used and where you might get it.
This is very much a "prototype" build and posses very little polish, I would approach this Instructable as a very rough guide of what you should do, do not be afraid to substitute the parts I used for parts that you have or can get easily.
This is my first Instructable so I apologize for any shortcomings.
Step 1: Doin' Rails
I will start with the rails because I found it super simple to set the width of the dolly cart if you already have the rail made.
Parts and Tools (all costs are an estimate, I didn't pay close attention to costs because it scares me)
2 x 8ft 1" square aluminum tubing $30 each here in Canada probably much cheaper down south.
1 x 4ft 1/4 20 threaded rod $2
6 x 1/4 20 sex bolts...yeah (aka barrel nuts or Chicago bolts) $1 each.
6 x 1" steel hinges $2-3 a pair.
Drill bits and a drill and a 1/4 20 tap/ thread cutter, preferably a drill press to keep things straight.
Some thing to cut the aluminum tubing, I used my compound miter saw.
Step 1 Cut the rails to length
I originally used the full 8ft but found it a pain to move around and handle in general so I cut mine down to six feet leaving me with two 2ft pieces to use for other parts.
Step 2 Cut the cross members.
The overall width of my rails is 6.5 inches so my cross members are 4.5 inches long and I used 3 of them.. You make these any size you want, remember the width of your rails determines the size of your cart. This is also a good time to drill the holes where you will attach the tripods. Measure out the center of the cross pieces and drill a hole, I used a no. 2 drill bit then ran the 1/4 20 thread cutter bit into the hole. This will be the bottom of your cross members. test this on a piece of scrap first.
Step 3 Attach the cross members to the rails with the hinges.
I clamped it all together and then put the hinges in place to mark where to drill the holes. This is very important to get right so take your time and make sure everything is square and the hinges are flush and your holes are marked out correctly. After you have marked the holes for the hinges go ahead and drill your holes. You are going to want to drill the right size hole for the screws that came with the hinges. test it out on a scrap piece of aluminum, if the hole is too big the screws won't bite enough to hold it all together and the hole is too small you will strip the screw head or break the screw trying to get it in.
Step 4 drill the holes for the "clamp bolts"
These bolts are what make the rails rigid. You have to drill a hole big enough for the shaft of the barrel nuts to fit in. Mark the center of your cross members and transfer that mark to the side of the rails.
*IMPORTANT* DO NOT DRILL YOUR HOLE FOR THE BARREL NUT IN THE MIDDLE OF THE RAIL!!!!! make the hole as low as you can with out the lip of the barrel nut going below the bottom of the rail, you need the top of the rail to be clear for the bearing to roll on. See image.
Now you cut a length of the 1/4 20 threaded rod that will reach in between the two barrel nuts. You may have to trim it down or cut a new piece if it's too short, no worries this stuff is cheap. Make sure you get a good fit and you can tighten good, you don't have to tighten too much but you don't want any movement in the rail. You want to do this for all three cross members.
There you go! You now have a foldable rail!
Step 2: Laying Tracks
This is the part that you will need to figure out for yourself. I will show you what I did but the parts I used I don't know what they are or where they came from.
The good news is that there are cheap parts made for this purpose but I wasn't going to spend $20 to ship a $3 chunk of plastic to Canada.
1" square aluminum tubing. I used the bits cut off of the rails when I shortened them.
1 1/2 inch 1/4 20 bolts x 4 $.50 each
Timing belt clamps. I used some mystery things but you can get real one here. http://www.sdp-si.com/web/html/newprdbelts5.htm Just make sure you get the right one for your belt.
Timing belt. I used a HTD 5m 9mm belt. It cost me about $15 You can get one here https://sdp-si.com/eStore/PartDetail.asp?Opener=Group&PartID=30471&GroupID=343
As you can see from the pictures I used the chunks of aluminum to attach the clamp to the rail. The trick here is to make sure the belt is level with the pulley on your cart, That above all will determine how you mount your clamp, this is just how I did mine.
You will also notice that there are a bunch of bolts occupying a small space, keep this in mind when you are making your holes.
This step is simple. Attach clamp to chunk of aluminum, attach that to the rail, DONE! just make sure it is level with the pulley.
Step 3: Pickup Truck for your Camera
I didn't take pictures while I build this because this is the part that evolved the most of the six months I spent building this set up. I will do my best to walk you through it. If you are unclear about anything please ask in the comments and I will tell you everything I know.
3/8 threaded rod $3-4 bucks for 3-4 feet
3/8 lock nuts
3/4 aluminum angle $10? for 4 feet
10x30x9 Bearings $1 each you will need 10 of them. I have no idea what those numbers mean, it is what was on the box.
3/8x1/2 x1 bronze bearings $4 for the pair of them. These are oil impregnated sleeve bearings that the belt slides past by the pulley
Pulley $17 I used one of these. https://sdp-si.com/eStore/PartDetail.asp?Opener=Group&PartID=59827&GroupID=346
1 1/2 inch 1/4 20 bolts I used a bunch, buy a bunch, they are handy
Wire rope clamp I used 4 of these, I'm not sure what size I used just make sure that the 3/8 threaded rod fits nicely in it. http://www.homedepot.com/h_d1/N-5yc1v/R-100299148/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053
Washers that fit the 1/4 20 bolts, you can never have too many
1/4 20 nuts
1/4 20 lock nuts
Shoulder bolts? I lucked out and found these bolts at home depot and the sleeve bearings fit perfectly on them there is a picture below.
1/4 plastic pluming pipe, the whitish flexible stuff used on sinks? 12" is more than enough
Motor $50-60 PLUS SHIPPING. I used a .45 rpm Dayton gear motor. * notice that it is (point).45 rpm not 45 rpm* I got it from http://www.servocity.com
Ball head. I used a Benro BH00 it's cheap and works great, use what ever you want just make sure is has a quick release plate.
Some sort of metal to use as a base, I used a steel electrical box cover, make sure whatever you use that it is big enough to mount everything on.
I will deal with the electronics on the next step.
I'm not going to go oven every little step in this build, there are too many, the pictures should help on what I leave out. However don't be afraid to ask questions.
Cut the 3/8 threaded rod to length, 7.5 inches or so should do
Cut your 3/4 aluminum angle to length. This can match the length of whatever you use as a base plate
Drill the holes for the 3/8 rod in the angle. Now the placement of these holes is very important. I had mine centered but there was no way to make the motor to fit like that so I had to off set them. The measurement in between the rods was arbitrary, I just chose a stable looking width, you may want to put some more thought into it.
make sure you make your holes in the exact same spot on both pieces of angle, this must be straight so it can be square.
Add the bearings. It doesn't really matter where you place these just put them in the same place on both sides, don't worry about the "outrigger" bearings yet, we will get to those.
There is a picture below showing the bearing assembly. the nut on the bolt is used as a spacer. The plastic piece is a chunk of the 1/4 pluming, you will have to drill it out with a 1/4 drill bit , at least I did anyway.
So on the bolt it goes washer, plastic spacer, bearing, washer, locknut. Now this you might want to play around with to fine tune the placement of the bearing on the rails add washers or nuts as spacers as needed, remember that the bearings that go on the outside of the rails have to track above the flange of the barrel nuts.
Put the frame together. this is where the threaded rod shines. Place some nuts on the rods then slide on the angle pieces and adjust the nuts so the bearing sit flat on the rails and the frame is square. It is a good idea to use lock nuts here because you don't want this to move after you have it set up.
Mount the other two bearings on some sort of material, I used some aluminum plate I had. drill some holes on the angle to mount the outriggers. Place the frame on the rails, make sure the the bearings are tight to the bottom of the rails and tighten down the bolts to hold them in place. Now the frame is locked on to the rails. you can slide it off of one of the ends or collapse the rails to remove it.
Add the top plate. Place the top plate on top of the frame and mark the location of the rods, then get your wire rope clamps and figure out where to drill the holes. I should mention that I had to add nuts on the clamps below the top plate to lift the plate over the bearings. After you mark your holes go ahead and drill your holes. It is a pain to clamp this together but if you are taking on this project then I'm quite sure you can figure it out.
Mount the motor and sleeve bearings. You want to place the bearings as wide as you can to lower the angle to the pulley.
pick your spot for your motor, drill your holes. very straight forward.
Blast a hole to mount your ball head. Remember to leave room for your electronics.
Step 4: Kill the PWM
This is how you control the speed of the dolly and stop it from tearing itself apart.
Bidirectional PWM. I bought this one. http://cgi.ebay.ca/DC-Motor-Speed-Controller-Forward-Backward-Switchable-/140357279325?pt=LH_DefaultDomain_0&hash=item20adf21e5d This PWM came with the directional switch and the POT.
Enclosure I used the 1591SFLBK from Hammond Manufacturing.
Hook up wire. 20' will be lots
4 switched DC power jacks
4 DC barrel plugs
2 micro switches
* REMEMBER TO CHANGE DIRECTIONS BEFORE YOU UNPLUG THE SWITCHES* When the micro switches are unplugged the system will be live with no safety.
Basically the goal here is to shut off the power to the system when the cart is out of track. Before the positive from the battery reaches the PWM I ran it through some switched jacks and micro switches. The reason for the switched jacks is that once one of the micro switch is tripped there is no longer and power to the system so you can't move the cart, I have it set up so that if you diconect the switches they will be by passed and the power will go straight to the PWM. see the schematic below for a better idea of how I wired this up.
* REMEMBER TO CHANGE DIRECTIONS BEFORE YOU UNPLUG THE SWITCHES*
Find a place on each side of your cart to place a micro switch so that it will contact something at the end of the run. Connect your wires to the common and normally open pins. once the lever contacts something the positive to the PWM will be cut off and your cart will stop moving. When you are adding the barrel plug to the wires going to the micro switch it doesn't matter what post you connect them to.
* REMEMBER TO CHANGE DIRECTIONS BEFORE YOU UNPLUG THE SWITCHES*
Step 5: Extras
Here are a few extras you might want for your dolly system.
Stubby little legs.
I made these for simple low, level shots, my cheap tripods wobbled too much in the wind , these are solid.
I used two 8" chunks of left over aluminum tubing and some fiberglass pole I had lying around. I would recommend using aluminum pipe instead but I'm broke and already had these.
Drill two holes about and 1 1/2" in from each edge with a #2 drill bit and thread with the 1/4 20 bit, this is where the legs attach. Next mark the center of the top the square tube and drill a 1/4" hole straight through. I added a 3/8 piece of HMWP (high molecular weight polyethylene, hockey boards) as a spacer for two reasons. 1 i needed to raise the track a bit so that the top of the legs would clear the rails. 2. The HMWP keeps the bolt from falling out when not attached to the rails. I simply drilled a 1/4" hole in the center of a 4"x3/4" strip and drill and counter sunk two hole for screws to attach it to the tubing.
Now the bolt. Cut 2 3" pieces of 1/4 20 threaded rod. What I did was sandwich a wing nut in between two lock nuts to "lock" the wing nut in place to act as a handle. what I do is I give the bolt assembly a couple of turns into the bottom of the rail then tighten the second wing nut for a very snug bond.
Lastly I added some wood into the ends of the legs to stop the fiberglass from getting crushed when tightening the adjustment bolts.(this is why I would recommend you use aluminum.) by loosening these bolt you can adjust the legs in order to level the system, I am impressed with how well these work.
This is very simple. I used the white drainage PVC for two reasons, it is lighter and cheaper than the black stuff. Cut the lenghth a bit longer than your rail, it gets longer when it is folded and i added some Styrofoam at each end for some padding. after its cut glue on a solid cap on one side and a screw cap on the other, Dry fit everything first to make sure your cuts are good.
For the straps I used some shoulder straps from some old camera bags and used 4" hose clamps to attach the straps. Find the balance center and go from there making sure the straps are long enough to use as a back pack, I left one strap a bit longer than the other, this tilts the pipe at a bit of an angle so it's not dragging on the ground.
Carry case for the cart
Here I lucked out big time, I found a $10 tool box at WalMart that the cart fit in perfectly. It is made by Plano and is Model 761 http://www.planomolding.com I simply cut wood to raise the "outrigger" bearing off the bottom drilled some holes for the bearing bolts to fit in and all done. I know the case protects well because the handle came off once and the case went crashing to the ground, the cart was 100% fine. P.S. I discovered that the handle can come off so watch for that.
Step 6: Just some notes
I know this wasn't as thorough as it could have been but I have very little free time. Like I have mentioned before I am happy to answer and questions you have and will edit this instructable to put in anything I may have missed.
I hope you enjoy your time lapse dolly, go ahead and link any videos you make with it in the comments here!