Newbie- Need ideas for simple 1 axis cnc motion rig

[Cao314159]

Hello all! First time poster, long time lurker. I have been studying and learning from this site for a while, and thank you all for teaching me so much. I am finally ready to get my feet wet in some basic cnc, and would really appreciate any help I could get!

The project:

I have been trying for a while now to find a way to get perfectly smooth and slow dolly shots for use in film. Trying to push a cart or drag a sled usually ends up in a bumpy and uneven shot. I thought a 1 axis cnc machine would be perfect for the job!

I am more interested in even, slow motion so I figured an ACME screw would be a good idea due to the gearing. I have a few tools but no shop, so I wanted to explore building something out of 80/20. I have never built something out of 80/20 before, and the list of parts is staggeringly large! For the motor itself, I thought I might just use my R/C brushless motor and radio, for easy speed control in the field (I am totally open to other suggestions).

I have a design in my head, but could do no better than sketch it out (I do not know how to use CAD). The ideal size would be around 4 to 6 feet of travel, with a gantry width of about 8 - 12 inches. Any suggestions/help would be greatly appreciated!

Thanks, Cao314159

[CNC Lurker]

Is the dolly only for the camera? How fast do you need it to go? The reason I ask is that at 4-6 feet, you could get whip on the lead screw if it is spinning too fast, so you might want to think about rack and pinion if you need speed.

You might want to look at the CNCRourterParts mechanical items: CNCRouterParts LINK

Also, does this need to be CNC? Using your brushless motor, you could use a speed controller such as those sold by MLCS: Router Speed Controls LINK You would probably have to rig it to run in reverse.

[Cao314159]

The dolly is just for the camera, and I would like it to be super slow, I don't think whipping will be too much of a problem. As of now, it does not need to be cnc, although in the future a finer level of control would be great!

Great link, looks like a solid product. It would be great if I could find a motor that could plug into that system and couple to the leadscrew, as well as a way to reduce the gearing....

Thanks for the input!

[RomanLini]

I would suggest rack and pinion too, because it has another advantage that it is not length-critical.

You could even have "rails" with rack that mate together so you could build long runs. Heck you could even have curved pieces if you can get a curved rack!

Anyway I'd explore rack options where you can get the rack in mating lengths.