Video up and processed. I hope this helps :)
https://youtu.be/RvwABSv9wEQ

Should have a video up in about an hour to show whats going on. I'm just waiting on youtube to process the upload.

it has stopped working since the one time i pressed timer utility and broke it that way.

and there are problems with not connecting, things happening when they shouldnt, and also things being converted to station when they should be ship.

safety interlock merge blocks may need to be turned back on, still figuring it out.

okay. turns out pressing timer utility breaks it. timer welder start actually initiates the whole thing.
proper order is:
1) detach any merge block labelled "Car merge"
2) fly up to the top and using a piston go to the info tab and press convert to ship.
3)Press either of the buttons that says "un/lock B start"
4)press the button that says "welder starter start"
5) set up the projecter to always display rather than display visible.
and don't touch anything else or it breaks.

Sorry for not getting back to you guys sooner. Thanks for the video @blazingImp77151, Tombstone2U is correct both arms were not extended so the projector, didn't move into position. good news was that you were almost there. the problem was that you used the centre button pad instead of the Right hand one. the centre button panel is to go up and down once the tether was build to the height you wanted.

Problem is that the bottom connector needs to be attached for the projector to work correctly.

https://youtu.be/atTlPRZfy0Y it's still processing as of when i post this comment, but here is me making a new one, trying to do a loop, and upon failing proving that A) the top was in station mode, and B) the pistons refuse to extend even with it in ship mode.

I won't have video until the morning, but I literally spawned it in from a blue print, and followed your instructions here in the comments. After it not working for several loops, I went looking for a solution and I decided to check if thing were set to station rather than ship. The top part of the lift was set to station when disconnected, so I tried fixing that, but to no avail. I will get back to you with a gif or something (I don't know how to go about it) sometime tomorrow.

@AeonYue this also happens when building via blueprint in survival.

Hi BlazingImp77151, I think I suspect that I may need to see what you are doing in order to understand what's happening here.
If you've destroyed a named part then I'm afraid that the timer blocks won't be able be able to effect an action involving it. Please check the timer blocks to see if any of the setup actions have been greyed out. This would indicate that the timer blocks can no longer see that component.

Everything seems to be working fine, but the central column of pistons will not extend at all. also since i destroyed and replaced it, the piston with the welders on it is staying unextended.

Note #1. Once started, it won't be easy to stop. you'll need to used the stop commands for the direction of travel at that time. These will be in the centre carriage control panel and must be triggered after both arms are in contact with the tower. if you stop the process in the wrong place there is a chance both arm will unlock, and the carriage will fall.

Note #2. Due to the space engineers hard cap on grid blocks, you will not get much higher that 4-5k in height. Any higher and the carriage won't be able to lock onto the tower and will fall back to the surface as a result.

If you have anymore problems then give me a shout, and I'll see what I can do.

Next the carriage arms need to be extended towards the tower. this can be initiated via triggering timer blocks titled "Lock/Unlock B" or pressing the 3rd button on the right and left carriage control panels.
Lastly to start the welding process hit the "Welder Starter" timer block, via the 4th button on the left hand carriage control panel.

Right I understand whats going on with this version. The reason the grid wasn't building itself was because the projection was aligning to grid correctly.
First ensure that both Top and Bottom Car Merge blocks are in the "Off" state.

Give me a moment, I've just fired up a test world to refresh myself on this one. Its been a while since i worked on this blueprint. :)

If you're able to provide detailed written instructions I'm more than happy to record a video tutorial

I've done both of these however I'm not sure how else to set up the carriage for its first welding operation?

Morning folks, I haven't created a video for this I'm afraid. Can you tell me if you have released the interlocks holding the carriage to the base station. Also has the projector turned on and is projecting the next segment of the central pillar.

It won't even move for me. like the pistons that connect to the conveyor line works, but nothing else does.

Are there any videos on how to set this up? I've tried getting this to start welding but it's not working