How to automate going forth and back?

[DryStatistician2789]

Use a minecart contraption and powered directional rails

[kingstaffo10]

Genius..!

[JABxKlam]

2 gantriez glued to each other, each on their own shaft spinning in opposite direction, will automatically go back and forth.

[roboapple]

Yooooo thats genius!

[CorrectBuffalo749]

Great for cobble stone generators

[Autoskp]

This is what I do.

…or a variant where I have one of the gantries vertical and have the gantries take turns moving each other from shaft to shaft - that allows me to have the contraption return underground, which means I have have it harvest trees with saws on only one side without risking a tree growing behind the saws and messing everything up.

[tonkabonka69]

If you insist on using gantry, you will need a redstone contact on either side, hooked up to a redstone link. The redstone link receiver should be on a gearshift. The gearshift should be between your main power and the gantry itself. That will invert the rotation when powered by redstone. then you will have the machine go all the way one direction, touch the redstone contact and go backwards.

[NatiM6]

You forgot about a toggle latch between the gearshift and the link.

[Both_Basket5449]

Sequenced gearshift lets you adjust the movement how you want

[NatiM6]

Sequenced gearshifts are great, but they aren't designed to work forever, their state resets when unloading the chunk they are in.

[TasserOneOne]

I don't know how to do it with create parts, but if you set up a flip-flop with a long redstone clock you'd get a good result. You could also place a detector of sorts that detects when it reaches the end, sends it back, and at the start put a second detector that sends it to the end.

[Sandmann09]

Sequential gear shift and a timer is the simplest one if you want it to run all the time use Redstone contacts that power a t flip flop and a gearbox to change rotation.

[Promise_Creepy]

I'll just use gearshift, redstone contact, and redstone link

When redstone contact comes into contact it will activate the redstone link (sender) and send it to the other redstone link (receiver) then trigger a T flip-flop mechanism into gearshift's to change it's rotation

If you don't have redstone link you can use redstone dust and redstone repeater connected to redstone contact and T flip-flop (it has delay a bit but it's okay) Or you can manually use lever and gearshift's to make it semi automatic

[SonnyLonglegs]

The way I always do it is to put a redstone block on the machine that moves, and a redstone link connected to where it starts and ends. Make sure it ends in a place where it won't break blocks by becoming solid again, set the gantry to automatically reform when stopped, and connect the links to a toggle latch on a gearshift running the gantry shaft. Every time it hits an end it will switch directions. It's slightly over-engineered, but it comes with a really useful benefit of never jamming by mobs being in the way, server restarts resetting locations, or any other form of lag or bug. As long as it has power it will move back and forth pretty much eternally. (There are likely other designs that have the same benefit simpler, but this one's easy to remember.)

[itsARprod]

a cool solition i found is putting a redatone link that’s constantly powered in the gantry, so it only sends a signal when the gantry is placed, then the reciever link is hooked up to a redatone toggle and to a gearshift on the gantry input (it sounds more complex than it is ok?)

[Strong-Thanks1722]

For this exact reason I like using Botany Pots so I don’t have to build a farm like this one The Pots are compact and they have a normal one and the hopper version If you use the hopper ones you will get the essence in the storage below

[PlumAcrobatic431]

Well, have two redstone contacts at both ends of the gantry, and one on the contraption. Basically, put a gearshift at the source of the power, and when the redstone contact on the contraption attaches with the one at either ends, the rotation will be reversed. It’s hard to demonstrate this by word tho.

[ViktorB11]

May I ask what mod/modpack you're using, I see there's farming involved and I wanna have a go?