So I was thinking of also attempting to utilize the structure of the MPCNC to use the gantry system for a large scale arcade crane game.
I’m wondering what weight you guy’s feel the gantry can support to pick up items… i’m looking to build the crane pretty large approximately 8 feet by 8 feet by 10 feet high.
What? Are you going to fill it with puppies or something?
That’s huge. The z axis can lift quite a lot. It’s very strong. I don’t want to put a number on it, but at least a six pack. But if there is a large weight at the end of a 10’ long z axis, it will bind or even bend or break something. Also, the x and y axes will not be very strong. You can add support to the outside rails, but the middle rails will bend. Just with the gantry they will flex a few inches.
Also, a 10’ z axis is going to be a mess. I don’t know if you can find T8 leadscrews that long. The 5/16" might work, but max speed will still be about 8mm/s. So, 3-4min to raise and lower it. Also, you’ll need 10 more feet above the machine.
Why so big? Especially in height?
If it’s an arcade crane aka UFO catcher, cable driven Z is the way to go. Build a big ass 2x4 frame, plexiglas/whatever the sides, lay 3/4 EMT rails across the top (10’, saves you the cutting lol) and a support every 2’. Mount a winch on the tool mount and don’t bother with any leadscrew or allthread. Double sheath the pulleys and you may be able to lift a kilo…
And you need a 4th axis with some very devilish programming for the claws… hehehehe
Yeah i wouldn’t use lead screw for z axis… it would be string or cable driven z axis to the claw portion.
i’m just worried about the flex in the x and y axis over that span. I could support the y axis every 2’ but the x would have to be free floating on the y
Depends on what you want to lift, stuffed animal, who cares if it has a bow in it. At 10’ there is not much that is not going to have a pretty good bow in it. If you need the rails stronger just edit the xy parts to have an open back so you can double up the rails. We don’t do it because that would sacrifice rigidity/accuracy, you don’t need that so double up the rails.
interesting… when you say to to edit the xy parts for the open backs to double up the rails i’m not sure I completely follow… does anyone have an example of this already done for another project?
No one has done it, most are more worried about accuracy.
The bottom of the rollers are open so supports can be added, in the same position the xy part has a large flat panel, you can remove that in cad and double up the rail.
I think the easy way here is to find some thick walled, rigid tubing. Pretty sure it would be able to lift around 8-10 kg without catastophic failure. That’s only a maximum load of 5 kilos per tube (not including the weight of the chassis parts themselves), so I’m pretty sure it’s fine since the goal is not to reach accuracy here.
An other possibility would be to have the tubes resting on the top part of the wooden frame, using printed support structures.
Last possibility: supported rails, secured to the wooden frame, like this:
https://www.google.com/search?q=supported+rails&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiAq4uq-ZrVAhXpy1QKHTAsAqgQ_AUICygC&biw=1707&bih=840#imgrc=_
In this case, you don’t even need to print the corner parts.
Otherwise, increase the tubing diameter, but this will need quite a lot of design.
I would think ganging together a few pieces of pipe might work. see this Thiniverse entry for an idea of joining the pipes together.
awesome… thanks for the suggestions and ideas!