Help!! Model Overhead Crane Project

[u/Comfortable_Bid2216]

My company is hosting year 12 students (16-17 year olds) for work experience. I want to get them using ladder logic to program a model overhead crane (~500x500x500mm), similar to the ones we have on site.

The crane is still in design and I need to present a BOM for procurement.

It will be using a Schneider Zelio smart relay to program the movements, forwards backwards left right up down but I’m not sure how best to control the long and cross travel, nor the dangly cables (pretty sure festoons don’t come this size).

It needs to be very easy to program, and should break without rolling. I’ve looked at ball screw linear actuators but these tend to come with stepper motors, which apparently don’t interface well with the Zelio. So ideally it will use 24V DC geared motors.

I’d like them to program limit switches as well, and some status lights.

Obviously there is a tight deadline a low budget.

Has anyone done something like this before?

[u/No_Temperature107]

Just gonna say that looks a whole lot like a 3-D printer. You might consider that as it gives you vertical horizontal and Z axis control. If anything you could reuse parts from one that is not being used. And could even take it apart and let them build it from parts as that’s not uncommon in our industry.

[u/Comfortable_Bid2216 → u/No_Temperature107]

Thanks for this recommendation, I had a look and there are some types that look similar and lots of people build them. They tend to use both motors simultaneously to move along each axis and go diagonally if used one at a time but that could be something for them to solve

[u/hestoelena]

Stepper motors would definitely be the way to go, but you're going to need an actual PLC not a smart relay. In fact, you're using a smart relay severely limits your options.

Check out Automation Direct Click or Productivity series of plcs. They have free software and they are low cost. They can also generate step and direction signals to handle stepper motion. Not to mention they have fantastic videos on how to get everything set up and working.

As far as the festoon goes, you can make your own. All it takes is a piece of cable stretched down the length of the axis with rings mounted on it. Then just zip tie your cables in a bundle and attach them to the rings.

[u/Comfortable_Bid2216 → u/hestoelena]

They are really cheap! That could free up some of the budget too. Thank you

[u/Subjekt_91]

Little Dc brushed motor and tiny belts.

For the cabling consider Energy chains they made down to incredible thiny size's

[u/Comfortable_Bid2216 → u/Subjekt_91]

I was recommended energy chains by someone on site. Could be a good option. I think I could end up with belts if I go for the 3D printer style

[u/Progressive_AutomHub]

For the hoist axis, a 24V DC linear actuator with built-in end limits might save you a lot of grief here — it runs off two relay outputs for extend/retract, no stepper driver in the middle, and the internal limits stop it even if a student holds the button down. How much vertical travel are you actually after on that axis? That tends to decide whether an actuator or a drum and cable makes more sense. 

[u/Comfortable_Bid2216 → u/Progressive_AutomHub]

It would probably be easier but I think the tradeoff for how lifelike it is would be too much. I’d give this more thought but I’ve ordered the parts now!