They are essentially just vanilla welders with a larger radius. So you use them just like normal welders.
You put all those you've built in a block group and toggle them on/off with a button panel, sensor, cockpit hotbar, timer block, or whatever else.

Can we please have a tutorial on how it works and how to properly use & set up?

it still working

does this still work?

decided to blow my world. sad choice but it's necessary....

All good, lad. I hope you find a way to fix your world.

sorry. i tested my self. maybe my world is broken or welding power is overwhelming. the bug it is when i build welder in survival the building progress is not reach to functional level.

here is example.

add all components - > building Welder - > stop at 78% Or Lower

i try vanilla welding blocks but that block made same result.
Look like my world broken. sorry for take your time. thank you for answer my question.

I've made a test world to try the mod again myself, but as far as things go here, everything is fine. The world has the steam release of this mod as its only modification.
I was able to construct all blocks fully in survival and have them weld up a block. By all accords, things seem fine here.

You're saying you cannot construct the other blocks? As in you weld them with all the items ready but the progress bar just doesn't go above a certain point?

Try making a new world (empty loads the fastest) with just this mod to see if you're able to use them properly there. Just set it to survival and use ALT+F10 creative mode tools. Just place one down with the tools on, toggle the tools off again, grind it down and try to build it again from scratch. Then we know if the mod works fine on its own as it does for me. If it does, I guess you can tell me the mod list you run on your 'broken' save and I can try to see if it breaks for me with those as well.

i don't know why the welder can't build. Flat welder can be build but 81%. before update done well but now don't work. can i get a help?

@Thundermane, yes, that's the gist of it.
The vanilla welders and grinders project this orb-area in front of them in which their effect takes place. This (legacy) mod basically just adds welders and grinders that have had the size of that orb increased substantially, to the point you can envelop entire ships with but a handful of them. This area has no collision, but it can harm the player in survival mode when the tool is on.

If you use the Buildinfo mod, you can make this area visible to you while placing them.

Made a quick video of the grinder part of the mod.
https://youtu.be/k8L_1bFzAwg

Greetings, so if i understand right this mod has an pass-through area-of-effect grind and welding capabilities?

@Silver I know this is long overdue, but yes you can!
When I first read your reply I didn't have much time to work on it and forgot... now due to reasons totally not involving friends building a continent worth of grinders and lagging the server, I had the same idea and remembered your request.
They're now available. If anyone dislikes this and wants a 'welders only' version, I can provide.

Hmm. I'm kind of wondering if it wouldn't be worth it to try just recreating new models from scratch, seeing as they're not particularly complex. I've been meaning to get back into the modding scene, and just a different type of welder with simple geometry sounds like a good entry level project I could try.

I hoped they were there in the XML, too. I was hoping since it clinged to glass so much it was determined by material. That makes no sense of course, but then again, this is Space Engineers.

One of the things I couldn't say due to the character limit is that I do have the original files, they're hidden in the mod by the original author. However, current versions of Blender no longer have a feature the game relied on for its models when this mod was originally made...
I could downgrade, but I'm unsure as to that being relevant still after seven years. I suppose this SDK Keen made has replaced it since or something, since the description says it can translate models to a format the game understands. But again, no concrete wording on that being true either.

Oh, is it impossible to edit that because you don't have the source models or something? I've done modding, but not modeling. Speaking from ignorance, I had assumed all the properties, such as air tightness, were in the XML file?

Since figuring this out is a bit of a nightmare, I suggest you use this workaround for now. It’ll sound trashy as a reply from a “dev”, but it’s the best way to get your creation going, at least anytime soon.

I’m sure you’ve already done this, but as for the flat square part, place a catwalk flat on its rim and cover the glass in windows.
I think the mod mistakes the defined mounting surfaces as being the airtight-box-thing as well. Because the old dev disabled placing on the glass, all glass has become gas-only-holes.
This makes the strut airtight and the flat one easy to cover, but the corner may need some creativity.

I didn’t even know they weren’t airtight. I never tested nor read the build info properly I guess.

Due to a lack of proper documentation and sources posing problems I can’t describe while staying under the 1K character limit of a reply, I can’t fix the issue easily. (Everything is vastly outdated, promised features missing from tools, etc, etc...)

Any way to make these blocks air tight? I'm trying to make a hangar that repairs ships that dock inside it. :)

oof, rip

Well, to be honest, I was indeed very skeptical of it at first. I'd be lying if I said I didn't think just that on first sight.
However, after some digging, it seems Keen has partially partnered with this website now to handle Space Engineers mods. I suppose it's for Xbox players or something, as they don't have access to the steam workshop.

The annoying part of this is that they're also forcing it on the Steam players. There's a prompt in-game now to accept mod.io's terms of service...

it's probably some kind of dodgy piracy/theft site

thank you

I had never heard of that website before until you asked me this just now... Keen's having another adventure, I see?

Nevertheless, I am here to bring you good news: It's been uploaded to mod.io. Similar name, so I trust in your abilities to find it.
Am I a good dev now? :)

I've done a quick test and everything seems to be working as it should when downloaded from there.

can I have permission to upload this mod to mod.io plz sir or can you upload this mod to mod.io plz

could I suggest a 1:1 slope and 1:2 slope diagonal piece so we can make circles or circle-like shapes with this?

nice, thanks.

Certainly can, and already done!
It seems the names it had before were the exact same as their intneral names... I'm not sure if this was done intentionally by the original developer or not. I frankly didn't notice until you posted this comment.
I also tweaked the superconductor cost of the strut part to better fit its cheaper resource price.
I made some patch notes for the tweak if you care to read them. In any case, the names are now completely underscore-free and actually fit in the 'building info' to the right when placing one.

could you fix their names? I feel like I'm just reading the code, instead of "Fly-Through Welder - Flat" or something similar.

oh my god thank you so much for fixing this!

been trying to build a thicc ship and the game decided it didn't like me placing fly-through welders lol.

wow so cool to this the Kodiak Biak !

Man, this mod is a blast from the past... nice job restoring it back to working conditions.

So yeah, loading a new world I did not crash once I tried to place it, so it does have to do with the world was made with the old mod activated

okay, I think I know what might be causing me to still be crashing and I never thought of this till now. This issue may be that I created a world with the original mod and then uninstalled it and installed this mod, and because the world had the original mod, and I edited the mod list from the loading screen, the game might treat it as if I had the original mod, I will try making a new world to test this possibility and report back with what I find

I've done a few tests but I seem to be unable to recreate your issue under normal circumstances. I have placed all three blocks in Creative and Survival, grinded them down and welded them back up, in both an off and on state, on both a powered and unpowered grid. It was also successful in welding every ship I tried to weld with it. Throughout my testing, the game never ceased to run.
The only way I was able to get the game to crash was by involving the original mod, either by replacing mine with it or by loading it in addition to my mod while giving it priority over my patch.
I will change the name of the mod to have [FIXED] in front to make it easier to distinguish the two in the mod browser.

Make sure the fixed mod is either above the original in the mod list, or the original is not loaded in the world at all.

Are you sure you aren't using the original one? I tested this with a few friends, their games worked fine.

you say you fixed this mod yet I still crash upon placement