Stop Motion Camera Dolly From Re-purposed Parts

This Instructable describes the creation of a camera dolly from re-purposed parts.
The dolly was created to film our Instructables Creative Reuse Hackerspace Challenge Night Stop Motion Video
Our final video can be seen below:

In the theme of creative reuse, the dolly was mostly created out of old Roller Blades and leftovers from other projects. This dolly was used to support the camera and allow smooth horizontal movements of the camera in a straight line. To accomplish this the dolly uses 3 wheels on top of the table, supporting the camera and 2 more wheels along the edge of the table to keep the dolly square to the table.

Step 1: Supplies and Tools

For my dolly I decided to use steel for the frame since I had some bar stock left over from another project.
This is not a requirement the frame could easily be made out of wood as well if you update the dimensions to match your lumber.

Supplies:

5 Roller Blade wheels. I used official "Roller Blades", but any kind should work. You may need to update some of the dimensions based on the diameter and thickness of your wheels. Also verify the inner diameter of the bearings in the wheels and update the bolts and washers to match.
5 6mm washers to space the wheel bearings off the frame and give proper clearance. 6mm washers were used over normal 1/4" washers due to the closer fit around the mounting bolts. The 1/4" washers would not press on the hub of the bearing and caused a lot of drag on the wheels.
5 1/4"-20 x 1.5" long bolts
2 1/4"-20 x 3/4" long bolts
2 1/4"-20 nuts
1 1/4" lock washer
1 1/4" flat washer
Optional, but highly recommended, camera ball head like this http://www.ebay.com/itm/like/111208533754?lpid=82 I got my ball mount off a broken security camera. Make sure the ball mount had a 1/4"-20 threaded hole on the bottom and a 1/4"-20 bolt on the top (standard camera tripod mount)
35" of 3/4" steel square tubing
25" of 3/4" steel angle iron
29" of 3/4" steel flat bar stock

Tools:

Chop saw or hack saw to cut steel bar stock
Welder and supplies (wire feed / MIG works better than stick see notes later)
Optional, but highly recommended welding magnets like these http://www.harborfreight.com/catalogsearch/result/index/?q=welding magnets
1/4"-20 tap and handle
1/4" drill bit
7/32" drill bit
pilot drill ~1/8" or less exact size not important
automatic center punch or punch and hammer.
1/4" end mill and milling machine -or- Dremel tool with fiberglass cut off wheels
7/16" socket and ratchet -or- 7/16" wrench -or- crescent wrench
flat screwdriver

Step 2: Sketchup Drawing

Attached is my Sketchup drawing I made up to plan out the dolly. For the most part the final version of the dolly matches the Sketchup other than the vertical brace is longer on the final version.

If your parts greatly differ from what I used I would highly recommend you update the sketchup drawing with your part dimensions and make sure everything fits before cutting anything.

Camera_mount.skp
Download

Step 3: Assembling the Base Frame

!!IMPORTANT!!
If your steel is galvanized you MUST remove the galvanization via grinding or acid BEFORE welding. Burning zinc is VERY toxic.

As mentioned in the supplies and tools step I highly recommend wire feed / MIG over stick welding for this project. Even using the proper size rod, on one current setting I was unable to strike an arc while the next setting up would strike fine but was hard to get a good weld without burning though the thin wall of the square tube. The MIG welder had finer power settings and once set up had no issues with striking a arc (just point and pull) and had no issues with burn though. Also as a bonus little to no slag on the welds when finished.

Also worth mentioning the sketchup drawing is an ideal dolly and for most applications that level of precision is NOT needed. These instructions, and for the most part the final dolly, were rounded to the nearest fraction of a inch.

First cut two 12" lengths of square tube. Make sure one piece either has a factory end or one cut is very square. Place that square end against the other 12" section to make a T. Use the welding magnets to square up the joint and make sure the edges are flush. The top of the T should be shifted over so there is 6.375" between one end and the side of the intersecting square tube. (see the sketchup drawing). Once it is all squared up and ready, tack weld two opposite corners of the joint. Once they are secure, remove the welding magnets and finish welding all the way around the joint.

Next cut a 1.5" length of flat bar stock. Weld this to the bottom of the T so it overhangs to the 6.375" side. (again best to see the sketchup drawing for location) This is the third wheel mount.

Next cut two 4" lengths of square tube. Clamp these as shown to the T 1.75" from each end of the T to the side of the 4" square tube. Use the welding magnets to square up the 4" tubes to the main body T and flush the ends. Secure the tubes with clamps and then weld in place. These are the table edge guide wheel mounts.

Next cut 3/4" long section of angle iron, 3/4" long piece of flat bar stock, and 2.5" long piece of square tube. Weld the angle iron to one end of the square tube such that the back of the angle iron is flush to the end of the square tube. (see photos) a welding magnet is good for holding the two parts flush while starting the weld. Then on that same end weld the bar stock to one side so that half of the bar stock stick past the end of the square tube. (again refer to the pictures or sketchup drawing.) This is the camera mounting bracket.

Step 4: Making the Slotted Angle Iron Vertical Support

First cut a 24" long section of 3/4" angle iron, make sure one end is a factory cut or take extra care to make this cut square.

I used a milling machine to create the slotted angle iron. This by far is the fastest way to cut the slot. If you use this method use a center cutting 1/4" end mill (roughing is fine). Plunge cut the starting hole and use plenty of oil and slowly feed the part into the bit. Watch the free edge of the cut, if it starts to vibrate use a clamp to connect it to the main body (as shown) to maintain the spacing and eliminate vibration.

Alternate method of cutting the slot:

On the inside of the angle iron find the center between the wall of the far leg and the edge of the leg you want to cut the slot in. Next mark a spot 1" from each end on this center line. Use a center punch and make a dimple at these 2 points. Drill a pilot hole with your ~1/8" drill bit at both locations. Then drill out those two holes to 1/4"

Draw two straight lines parallel to the long edge of the angle iron from the inner and outer edges of the 1/4" holes. You should now have the outline of the 1/4" wide slot that is 22" long. Using the fiberglass cut off wheels on a Dremel cut along both of these lines and remove the center. NOTE: start by cutting the line nearest to the edge then the inner line.

Use a 1/4" bolt when finished and make sure it slides along the entire length of the slot without binding up on the edges. If it binds up, use your Dremel and either a cut off wheel or grinding stone to open up the slot where the bolt bound up.

Step 5: Mount the Vertical Support and Brace

Before proceeding on this step, take the camera mounting bracket and hold it on the vertical support. You want it to attach with the bar stock edge bracket on the side of the vertical support with the L of the angle iron, NOT on the side with the thin piece of metal. (see pictures and sketchup). Once you have the camera bracket placed, mark the end of the vertical support that the 3/4" long angle iron welded to the camera bracket is on as the top. Verify the other end of the vertical support (the bottom) has a nice square cut before proceeding.

Next place the base T so the edge wheel supports are down. Measure back 9" from the base of the T (third wheel) and draw a line across the tube. This is where the front edge (the side with the slot cut in it) of the vertical support will be lined up. Use welding magnets to get the vertical support square to the base and flush on the side. Tack weld two corners then remove the magnets and fully weld the joint.

Next cut a 24.5" long section of 3/4" flat bar stock and weld it between the end of the T and the top of the vertical support as show. This is a brace to help prevent flexing of the vertical support. Exact placement is not critical but the higher on the vertical support you mount it the more usable vertical adjustment you will have without removing the camera mount.

Step 6: Tapping the Holes

If you do not have a tap you could drill a clearance hole and use a nut on the inside of the tube instead. Due to the limited space this is not recommended.

First mark the locations of the 5 wheel mounting holes.

Measure in 3/8" from each end of the top of the T and put a mark at the center of the tube.
Measure in 3/8" from the end of the table edge guide brackets on the bottom of the base and put a mark at the center of the tube.
Measure in 3/8" from the free edge of the bar stock on the bottom of the T and put a mark at the center of the flat bar stock
Place the camera mount on the vertical support so the angle iron is on the top side. Make sure the bar stock edge guide is along the side with the other leg of the angle iron and not the thin edge. Put a mark on the camera mount angle iron where the center of the slot is horizontally and the center of the camera mount angle iron vertically
On the camera mount top side (side with the angle iron welded on) mark a point 3/8" from the free end in the center of the square tube. NOTE this hole is NOT tapped and should be drilled out to 1/4"

For each point do the following:

Make a dimple using a punch at the point to be drilled.
Drill a pilot hole with your ~1/8" drill
Drill out the hole with a 7/32" drill (unless this is the non tapped hole in which case drill out to 1/4" and skip the rest of the steps)
Using plenty of cutting oil, tap out the hole with the 1/4"-20 tap. When tapping make sure you hold the tap square to the surface of the hole. Then only screw in 1/4 turn at a time. After every 1/4 turn back out the tap 1/2 turn. This breaks off the burrs created during tapping and prevents the tap from jamming. If the tapping becomes more difficult, back the tap all the way out and clean any shavings off the tap and the hole.

Step 7: Final Assembly

Take your 5 wheels, 5 1/4"-20 x 1.5" bolts, and 5 6mm washer and assemble on the bolt, wheel first then washer.

Screw the five wheel assemblies into the base frame locations as shown. When tightening the bolts you want them tight enough so they don't back out but not so tight that they bind up the bearings in the wheels. If a wheel does not spin smoothly or is very stiff, try loosening the mounting bolt.

Next take one 1/4"-20 x 3/4" bolt, nut, and lock washer and mount it in the camera mount. Pass the bolt from the inside of the tube so the threads of the bolt stick out the top. next place the lock washer and nut onto the bolt so the washer is on the outside of the tube. Use a flat screwdriver to wedge the head of the bolt against the side of the tube and tighten the nut down firmly.

Bolt the camera mount assembly to the vertical support using a 1/4"-20 x 3/4" bolt and flat washer. The bolt head and flat washer should be on the inside of the vertical support angle iron and the camera mount on the outside towards the third wheel on the base of the T. When tightening the camera mount adjustment bolt make sure the flat bar is against the side of the vertical support and the thin free edge of the vertical support is under the flat washer. The flat bar prevents the camera from rotating out of square when adjusted while the washer and the thin edge places even force on the clamping surface.

Finally screw on your camera ball head (if used) to the exposed 1/4"-20 bolt sticking out of the camera mount. Tighten enough so it will not unscrew easily but not so tight as to damage the mount.

At this point the dolly is ready for use. Mount your camera to the ball mount and set on the edge of a table so the edge wheels run along the edge of the table. When moving the dolly, press inwards slightly to keep contact on the edge wheels.