My Gantry Crane Build

[christian]

Yeah,

Nice fab job.

On the caster wheels; rather than sizing them up more to keep from making indents in the asphalt, I'll suggest that you just fab some take-up hardware that cause the wheels to lose contact with the ground when you're not actually moving the crane. A lot of heavy-duty welding tables utilized that method. You might even be able to use some 3" male and female pipe fittings and a circular plate that could have some kind of hex adjustment that would be heavy enough to rotate and lift each corner until the wheels no longer touch and for the best leveling, too; you know, like on a washing machine. It would probably only take about 1/2" of thread travel.

[av8or1]

Thank y'all for the feedback, I appreciate it.

I realized today that I didn't include a picture with a gratuitous inclusion of my welder. So I'll correct that now:

[av8or1]

Nice job. I would put and weld a piece of flat bar over the ends of the I beam to stabilize the I-beam and prevent any side to side deflection and possible collapse. The top part wouldn't matter much, but the bottom would especially if you are pushing or pulling under load.

Good point. Well, I don't plan on ever pushing the gantry while under load. However, in the pending work I do intend on installing a 1/4" flat plate on the ends of the legs, yes.

[av8or1]

What do you cut with? Have you tried spray arc on your 275p? I try to spray everything I can with the 250p. It's got power to spare and sprays very well using regular 75/25 gas. https://www.everlastgenerators.com/f...250p-Spray-Arc A tapered contact tip is key to not overheating your gun.

Alright, that is good to know, thanks. I'll have to give the spray arc thing a look during the next applicable welding project. That said, I must confess to not noticing when I read through the manual: does the 275p have a spray arc function? I didn't notice because I have used mine on but this one project thus far and that was exclusively SMAW.

Regarding the cutting involved in the project: I cut with my good ol' chop saw wherever/whenever possible. For some components that wasn't possible due to their size. So in those cases I used a metal cutoff wheel on a plain-Jane 4 1/2" angle grinder. Rudimentary but workable approach. For the longer pieces, I had the supplier cut those to length. However they don't exactly do precision cutting to say the least, so some cleanup work was involved therein. The I-beam (S10x24.5, 11' in length) was also cut by the supplier.

Thanks

[performance]

Spray arc is simply a combination of wire speed and voltage, with the appropriate gas. There is no "function" on any mig, just need the right amount of voltage along with the right wire speed to jump into spray with a MIG gas 20% or less rich in CO2. Pulse itself, should be a spray process, which is pulsed spray. That is what that is for.

[av8or1]

Yeah,

Nice fab job.

On the caster wheels; rather than sizing them up more to keep from making indents in the asphalt, I'll suggest that you just fab some take-up hardware that cause the wheels to lose contact with the ground when you're not actually moving the crane. A lot of heavy-duty welding tables utilized that method. You might even be able to use some 3" male and female pipe fittings and a circular plate that could have some kind of hex adjustment that would be heavy enough to rotate and lift each corner until the wheels no longer touch and for the best leveling, too; you know, like on a washing machine. It would probably only take about 1/2" of thread travel.

Ah I see. Sure, you could do that; I've seen several welding tables with that type of feature. Roll them around when you need to then pull a lever to elevate the table onto it's feet when you don't.

I suppose my only feedback on that is that those feet would likely cause small divots in the asphalt too, depending on their size. If large enough so that they could distribute the weight over a much broader area, then perhaps they would not do so. That said, to turn the gantry will generally mean that you must bring it to a stop, at least temporarily. And there the rub lies: it can be difficult to initiate its movement after a stop, especially if the asphalt is uneven or unlevel.

So the plan is to add 14" regular vehicle wheels to the crane, one on each corner. Those wheels can pivot as needed to make whatever turn you need/want. So in a way it would be like parking a light car on the asphalt. Thus the weight would be planted onto the surface via a tire, which is much less destructive to the asphalt than the casters. The casters would remain as-is; the sheer size of the wheels in comparison to those casters would elevate them off of the asphalt easily. And when you wanted to return to the casters, you could do so rather simply by supporting the crane with floor jacks and removing the wheels, leaving the pivots installed. Ergo, just removing the 5 lug nuts and then the wheels, just like a vehicle.

Here is an early sketch of the concept:

[performance]

If you are going to try to spray, use a 90/10 gas. People say you can spray with 75/25, but you have to have a higher voltage, which will indeed overheat your gun, and the arc will not be as stable, and the weld will not be as clean.

[av8or1]

Spray arc is simply a combination of wire speed and voltage, with the appropriate gas. There is no "function" on any mig, just need the right amount of voltage along with the right wire speed to jump into spray with a MIG gas 20% or less rich in CO2. Pulse itself, should be a spray process, which is pulsed spray. That is what that is for.

Oh wow, well then that shows you what I don't know about spray arc MIG!

You said <= 20% CO2 but in a previous post you stated that you can do spray arc with common 75/25. Is the latter correct?

[av8or1]

If you are going to try to spray, use a 90/10 gas. People say you can spray with 75/25, but you have to have a higher voltage, which will indeed overheat your gun, and the arc will not be as stable, and the weld will not be as clean.

Good to know, thank you!

[performance]

That wasn't me that said that about the 75/25. I respect Zoama. I've done it with it, but there is no comparison, and so many more problems and much less stability. I said 80/20, which is recognized as the lower threshold. Personally, I use a C18. This is a good mix for both spray and short circuit, and you get a cleaner weld in short circuit. It's not as hot, but it works wonders in spray too. For spray it does run a bit hotter than 90/10, but it does offer true spray capability. Let's put it this way, you can spray with a lot lower settings with 90/10 instead of 75/25.

[av8or1]

That wasn't me that said that about the 75/25. I respect Zoama. I've done it with it, but there is no comparison, and so many more problems and much less stability. I said 80/20, which is recognized as the lower threshold. Personally, I use a C18. This is a good mix for both spray and short circuit, and you get a cleaner weld in short circuit. It's not as hot, but it works wonders in spray too. For spray it does run a bit hotter than 90/10, but it does offer true spray capability. Let's put it this way, you can spray with a lot lower settings with 90/10 instead of 75/25.

Oh sure, I understood who said what, I just mixed my reply so that it appeared as though I had things confused. Apologies for that. I've watched a few YouTube videos regarding spray arc, so I know what it is and how it differs from short circuit MIG. However the takeaway I had from those experiences was that while spray arc has its purpose, the majority of the time short circuit MIG will be all you need. It seemed like spray arc was for structural MIG welding, if I can express it in that manner. So if you weren't doing anything structural, short circuit MIG was sufficient. Furthermore, "light structural" could be done by short circuit MIG as well. Whatever "light structural" meant.

I would like to attempt spray arc someday, even if it is merely for the experience gain. For the remainder of this project however, I'll continue putting the Lincoln rods to work. Every weld on that gantry, regardless of where it is located, has a minimum of a 3 pass weld, with 6010 as the root and 7018 as the fill/caps. In a couple of instances, I ran another 3 beads of 7018 over that, making it a 5 pass weld. I'll likely remain with that formula for the pending mobility work. Some experimentation with that same thickness of mild steel tubing and plate (before I began welding the gantry) showed that 90A - 95A worked well for the 6010 and 125A - 135A was the range for 7018. FWIW.

What you welded should have been spray arced. It is for 3/16-1/4" and up. Not just structural...but what you have there IS structural. lol. I spray mostly.

[av8or1]

[Previous post snipped for brevity]

What you welded should have been spray arced. It is for 3/16-1/4" and up. Not just structural...but what you have there IS structural. lol. I spray mostly.

A question: I didn't write the last line of this post. Anyone know who did? They put it in my post rather than creating a new post of their own. lol

[zoama]

75/25 works very well for me but when I want to spray thin stuff I blend in some straight argon with a quick connect tee. I use plain old air line quick connects.

I'm not great at continuing around corners so I stop and start. Here's some pictures of spraying 1"x1"x1/8" tube with some extra argon mixed into the 75/25. No pulse since I never learned how to use it. This whole set of shelves was welded with spray arc and it was all welded in the position you see them. I spray everything I can now because it's almost silent and there is zero clean up. No BBs burning holes in my clothes. I was going to make this a cabinet but decided to just leave it open.
If it works it works.

[zoama]

If you are going to try to spray, use a 90/10 gas. People say you can spray with 75/25, but you have to have a higher voltage, which will indeed overheat your gun, and the arc will not be as stable, and the weld will not be as clean.

I know you're teaching people the correct technical way to do things but spray works perfectly well the way I've been doing it. Not the slightest hint of an unstable arc, the welds are clean and the gun doesn't overheat even at maximum duty cycle of the machine as long as I use a tapered tip. A standard or heavy duty tip will overheat the gun quickly because the tip absorbs a lot of the radiant heat. I also use #23 front end parts so the screw on nozzle is insulated further reducing heat transfer. You can hold my profax gun comfortably bare handed after maxing out the duty cycle on 1/2" steel.
With a heavy duty tip the gun will be smoking in a few minutes.

You got me started spraying and I'm very grateful for that. All the other details I worked out through experience.

[av8or1]

I know you're teaching people the correct technical way to do things but spray works perfectly well the way I've been doing it. Not the slightest hint of an unstable arc, the welds are clean and the gun doesn't overheat even at maximum duty cycle of the machine as long as I use a tapered tip. A standard or heavy duty tip will overheat the gun quickly because the tip absorbs a lot of the radiant heat. I also use #23 front end parts so the screw on nozzle is insulated further reducing heat transfer. You can hold my profax gun comfortably bare handed after maxing out the duty cycle on 1/2" steel.
With a heavy duty tip the gun will be smoking in a few minutes.

You got me started spraying and I'm very grateful for that. All the other details I worked out through experience.

Can you show some pictures of your spray setup for your MIG gun? What is this tapered tip about? How does it differ from the standard tip exactly? #23 front end parts? Are those the smaller sized MIG gun parts that you're referring to?

Thanks!

[zoama]

Can you show some pictures of your spray setup for your MIG gun? What is this tapered tip about? How does it differ from the standard tip exactly? #23 front end parts? Are those the smaller sized MIG gun parts that you're referring to?

Thanks!

I replaced my original mig gun with a 20 foot long Profax brand 250 amp Lincoln/Tweco style and then changed the front end parts to use Lincoln/Tweco #23 insulated screw on nozzles and #14 contact tips. I believe the 250HD version comes with these parts.
You can see in the pictures that the tapered contact tip has almost no face to absorb radiant head from the arc. Standard and heavy duty contact tips have a large face and absorb a lot of heat from the arc that can melt your gun. Through trial and error I've learned that the tapered contact tips work well for everything so that's all I buy now.

Click the thumbnails for a larger image.



On my 75/25 tank regulator I use about 2 feet of plain old 1/4" air line like you use with an air compressor with a 1/4" male quick connect. On the mig machine I use about one foot of the same air hose with a 1/4" female quick connect. The cheapest way to get this hose with ends on it is to buy a cheap 6 to 10 foot air hose and cut what you need off each end. The hose clamps are for automotive fuel injection. Regular worm drive clamps won't seal and cause problems. My mig gun and spool gun are in the pics. The spool gun is also a Lincoln/Tweco style and uses the same front end parts as my profax. The gas hose is setup the same way on my tig machine so I can put the carts side by side and connect pure argon to the mig machine for aluminum welding or mix gas with the tee for a higher argon content than 75/25 when I want to spray thin material. I would spray 3/16" steel using 75/25 with ease. Anything thinner I would add more argon. Bumble bees shouldn't be able to fly, but they do and do it well.



The 250p MIG, 250EX TIG and PP60 plasma cutter have been going strong for about 8 years now with no problems.

[av8or1]

Thank you zoama! Great information. I am still using the MIG gun that came with the 275p when I bought it. As I recall the only variance that I have from standard is that I paid extra for the longer MIG hose. I also have the larger gun, though I forget the size now. I recall that there were two choices and I opted for the bigger one. I also bought some knurled rollers for doing flux core (FCAW). Other than that it was the standard/stock 275p. After using its SMAW for a while, I needed a new electrode holder ("stinger") and so I found one online, not through Everlast, and it has worked well since then.

I'll have to research your MIG setup when I return to MIG welding at some point in the future. You appear to have done a considerable amount of experimenting and thus research. Good work!

[av8or1]

So today was the big day. The distributor had completed their preparation of the components that I designed, drew and ordered. Fortunately, they were able to drill all of the holes for me and even radius-ed the edges of the fixed plates that will be welded to the gantry's legs. Thus all I needed to do was pick them up. And that I did:

[av8or1]

The metal was relatively clean too, which I was quite agreeable with because it means less prep time for me:


With just a flap disc on a 4.5" angle grinder, they cleaned up easily. With these types of projects (and I did this during the gantry build itself), I prefer to go with rusty metal primer even though I've ground off the rust:

[av8or1]

After reading Mark's feedback, I decided to go with some 1/4" flat plate, 10" x 6" to serve as the end caps for the H-beam legs on the gantry:


I do listen to feedback and thought that this was a good suggestion. Got those into primer as well: