Introduction: Actobotics 48 Inch Channel Slider W/ Auto Reverse & Speed Controller

In 2014, I built the's Actobotics channel slider for use with time lapse photography. The original build can be found using the following links:

Recently, ServoCity added some longer channel lengths to their inventory, including a 36" and 48" channel. When I built the original slider, the kit came with 24" channel from Actobotics. I thought why not try and build a slider using the longer channel, and play with some different gear motors. FYI, the easiest way to accomplish this would be to purchase the slider kit, and then buy the longer channel and belt to go with it. I chose to buy all of the parts separately, and this is a challenge because they do not sell all of the parts included in the kit, directly off the website. I'm sure if you called them directly, you could buy them, but I did some engineering to modify some existing parts to make it work. This slider automagically reverses direction when it gets to the end of the channel using a DPDT relay. Since this is a continuous motion slider, I'll use it with either my Sony NEX-5 mirrorless camera, or with a GoPro as shown.

Step 1: 48" Channel Slider: the Build

I'm not going to go into details on the exact steps to build the Actobotics channel slider, as there are already YouTube videos from ServoCity that show the process step by step. The parts list can also be found here. The main differences with my build is that I upgrade the camera trolley to use the full channel slider A, versus the channel slider D that comes with the kit. I also had to modify a Flat Channel Bracket with an angle grinder so that it would fit into the channel, as I wasn't able to find the Acetyl carriage bolt plate as a part that you could order from the website. This part comes with the kit, but I would assume that the nice people at ServoCity would sell you this part if you called them. I also needed to buy the 1/4"-20 knob and carriage bolt elsewhere. You'll also need to purchase the XL timing belt in a 10 foot length.

I also used a 1/4"-20 Round Screw Plate instead of using the little feet that come with the kit. I want to be able to attach this to a tripod more than I want it sitting on the ground.

Step 2: Testing

On my original channel slider, I used gear reduction to slow the camera trolley down in combination with the .5 rpm motor to traverse the full slider distance in about an hour. On this longer channel, I went with a 4 rpm motor and the servocity digital speed controller to see what results I could get. If I could do it again, I would probably choose a different motor. Using the current configuration, the camera goes 42" between the limit switches in 3 minutes and 30 seconds turned all the way up, and about 14 minutes 20 seconds turned all the way down. Considering that I'll personally use this for time lapse photography, I'll want the slider to be much slower. I think that I'll replace the motor with a .5 or 1 rpm motor in the future, and maybe use some gear reduction.

In the next step, it will show the relay wiring so that the dolly switches directions when it gets to the end of the channel and hits the limit switch.

The last picture shows the 24" slider and the 48" channel slider side-by-side. These are continuous motion sliders, but could easily be modified with NEMA mounts and stepper motors to be a move-shoot-move shoot slider. Just waiting for the weather to get nicer to go out an try the new longer slider!

Step 3: 12V DPDT Relay

So, just like the 2 foot channel slider I built, I wanted this one to switch directions when it got to the end of the track. To do this, I added a DPDT Relay with Limit Switches. The difference in this 4 foot slider is the addition of the digital speed controller from ServoCity. This allows me to slow the motor down during time lapse sequences, or run it at full power for video. The 4RPM motor doesn't move very fast anyway, but it is nice to be able to use the dial to slow things down when needed.

I mounted a short piece of channel to the end of the main channel to house the DPDT relay, which hides the wiring nicely. It also acts as a mount for the battery and the power controller using simple velcro. I also use 12V quick connectors so that I can remove them at any time for transport. I originally found the wiring diagram for this on, so I cannot take credit for figuring this out. I just copied what I did last time, and magic happened.

*** Please note that while testing I noticed that when using the speed controller at less than full power will cause the DPDT relay to fail. Looks like there needs to be a full current for it toe switch directions. The limit switches do make the dolly reverse, but only when the dial is cranked all the way up. If you aren't careful, the dolly could reach the end of the line and not switch directions and burn the motor out.