SS welding question for Zap et al

[walker]

I have to weld a bunch of (80') track for a rolling cabana out of 316l The track is 3/16" x 3 and in the center I am welding a 3/4" solid round bar. I only need welds every 12 -18" along the length. I experimented with a few different ways to weld it, as well as a few different processes to see what was the best I could produce with my equipment. I Tried MIG using .035 316 wire, in the groove (fillet), as well as TIG using 3/32 filler, and stick using 3/32 rod. I also tried punching the flat bar and plug welding. The TIG fillet was the best followed by the stick fillet. The thing I didn't like about the stick fillet was the clean up. So I settled on TIG using my Sync 180SD, 3/32 ceriated tungsten and 3/32 316L filler doing the fillet weld. For the test piece I just put it in the vise, but the track pieces are 12' long. I was considering clamping them to a 6" WF that I have and just setting it up on the bench. It is very convenient to turn the groove up, so that I am welding in the flat position, but I am unsure if welding all one side, then flipping the WF over and welding the other side is going to work well without creating a curve in thte piece. Is that possible, or should I leave the WF flat on the table and do one side then the other, orweld on one side, skip 12" weld on the other while the first weld cools then come back and weld the opposite side?
I don't normally weld a lot of SS, but can (and do a respectable job), I am doing this for one of my best customers as part of a much bigger steel project.
Thanks for the help.

[dave powelson]

A picture or quick sketch of what the profile is to look like, helps a bunch.

IOW-does the .75 round rest on the top of the 3/16" edge or is the round
to run along the center of the 3" flat.....or is it none of the above?

??What is the finished straightness requirement for form, fit and function?
.....and how is this checked?

Welding on one side--then hoping to flip and weld the other side--especially in SS--don't work.

Heat straightening is a poor last resort, when distortion control via pre-stressing
addresses the problem before the fact.

[walker]

The flat bar lays flat on the ground (horizontal), the 3/4" round bar sits in the middle of the flat bar. It forms a sort of railroad track. The flat bar also gets holes in each side to screw down to the ground. So, at each set of welds (1"ish long, one on either side of the round bar) should I place a small shim under the flat bar in the middle and clamp both sides down?

[zapster]

The flat bar lays flat on the ground (horizontal), the 3/4" round bar sits in the middle of the flat bar. It forms a sort of railroad track. The flat bar also gets holes in each side to screw down to the ground. So, at each set of welds (1"ish long, one on either side of the round bar) should I place a small shim under the flat bar in the middle and clamp both sides down?

If you can experiment with one section see what it bends in the middle and pre bend accordingly..

Even with spaced welds warping will happen..
Don't do opposite side welds either..
Stagger them from side to side..


...zap!

[walker]

So, weld one side, skip ahead 6" and weld the other side,zig zagging back and forth for the length?

[Baila La Pinza]

As always, many different ways to skin a cat....

So, if I'm understanding this right you've got roughly 160x 3" welds to complete?

IMHO TIG isn't the right process for this job, apart from it being painfully slow, you'll also put alot of heat into the material and have more distorsion to worry about.

We can all spend all day making pretty beads with TIG, but if you want to make any money from the job (I'm guessing that's why you're in business?) then I'd 100% use MAG.

As for distorsion, either clamp the flat bar to the bench with a filler rod across the middle to pre set it, or drill out some channel and bolt the flat bar to that, again with a TIG filler rod in the middle, whatever's easier.

Personally, I'd lay it flat on the bench and weld opposing sides, probably weld the end ones first, then the middle one, then work my way out from the centre.

[dave powelson]

The flat bar lays flat on the ground (horizontal), the 3/4" round bar sits in the middle of the flat bar. It forms a sort of railroad track. The flat bar also gets holes in each side to screw down to the ground.

So, at each set of welds (1"ish long, one on either side of the round bar) should I place a small shim under the flat bar in the middle and clamp both sides down?

As I mentioned prior "??What is the finished straightness requirement for form, fit and function?
.....and how is this checked?"
The end result required, dictates the assembly method. It appears
to me, that a little more study prior to the doing, might help you.

"sort of a railroad track"---IOW--this is 2 tracks that have to been straight, parallel
and flat to each other within what kind of tolerance?

Your current description sounds like somebody's idea of 2 linear ways,
which the cabana is located upon and slides on, via semi circular sleeves
with .750 ID. If this is v-tracked rollers--one still has the same problems.

Unless there's some good tolerance slop--and allowing one side of the cabana's sleeve(s) to float, to accommodate distortion, location error, etc.---
the assembly will bind up, etc.
If there's 2 sleeves on one track, with a floating, single sleeve on the
opposite track--that helps a bunch. A top view would show the sleeve locations
as the points of an equilateral triangle.

There's ways to pre-stress and minimize weld distortion, albeit with some
testing prior and scrapping of material---but there will still be some distortion.
Depending on a bunch of variables not known--this can easily trash the best
of efforts.

An alternative to welding would be:
.750 dia rod will nest inside 1" 'C' channel. Short sections, along with the 3"
flat are thru drilled, the flat countersunk, the .750 rod drilled and tapped for
flat head screw attachment.

In any case, locating and aligning these tracks on installation effects
how and if the assembly can slide.

If this is some architect's pipe dream, now's the time to raise the flag.

[walker]

Dave, ya pretty much nailed it on the head! It is set up like a v groove roller. On one side I will leave the wheels able to slide on the axle so that it won't bind. As far as total tolerance I could probably do +- 1/8" widthwise and not be too bad off. As far as up and down, I don't know. I will be able to shim things straight, but would just like it as flat as possible to ease the burden of trying to true it up when installing.
"If this is some architect's pipe dream, now's the time to raise the flag", It is, and that's funny! I did raise the flag, but they still want to go ahead.

[sn0border88]

Is the track going to be anchored to the ground in some fashion? If so, I wouldn't be very concerned with distortion if you can just bolt it flat.

Also, MIG is 100% the way to go here. Much faster, with lower heat input (less warping) means more money in your pocket and a happy customer.

[DSW]

Dave, ya pretty much nailed it on the head! It is set up like a v groove roller. On one side I will leave the wheels able to slide on the axle so that it won't bind. As far as total tolerance I could probably do +- 1/8" widthwise and not be too bad off. As far as up and down, I don't know. I will be able to shim things straight, but would just like it as flat as possible to ease the burden of trying to true it up when installing.
"If this is some architect's pipe dream, now's the time to raise the flag", It is, and that's funny! I did raise the flag, but they still want to go ahead.

I've got a bit of experience installing tracks as well as doing metal work and concrete over the years.

Are you responsible for the install or just the fab work? If you have to do the install here's a few pointers from having done tracks for X ray machine installs. Plan on shims and grout. Most people think of "level" as somewhere between the two lines on the 2' level if you are lucky. We used to have a tolerance of +/- 1/16" in 10'-12' IIRC. If not the heavy column would "walk" on it's own slowly moving down hill. Since the column in many cases weighed in excess of 2000 lbs over a very small foot print, if you had to shim ( and you almost always had to despite the call out for tolerances on the print) the track would quickly sag and the unit would bind. In these cases, we'd "over shim" so we had at least an 1/8" of material under the track and use nonshrink grout to fill and level under the track. A string line or laser will be your friend to take out distortion laterally, and a good laser level will get you dead nuts on for level.

If you don't do the install... Expect to get tossed under the bus and run over repeatedly. All the issues I just pointed out above will be tagged to you. Any distortion ( real or imagined) that's caused either by your work or the install will get laid at your feet. Been there. We had people complain about machines we didn't even install because they didn't work right. On the other end we had clients who complained because we had to raise the floor almost 2 1/2" to get even semi close to level. They didn't like the look of the grout.. They didn't like the fact the floor had to be flashed to get the tiles to lay sort of right... The didn't like the way it looked... and so on. CYA as much as possible on this. Lots of notes on issues up front and in writing so you don't get hit with charge backs and change orders.

If this was me, I'd agree with the others and mig it. Sounds like the 'track will be fairly "flexible" when completed. If I was doing the install, I'd anchor one end fairly securely and then using a laser or string line bend the track to straight as I went down each hole and anchor it to the concrete with at least 1-2 washers as shims if the grade was close. After I got the 1st one anchored temporarily, I'd level the whole thing and make adjustments. Then I'd do the same thing for track #2 using track #1 as the reference as well as a tight string line. At the end I'd go back and nonshrink grout the whole thing 100% shimming as needed.

I'm betting grade will be off significantly, especially outside where pitch is usually critical for drainage. I wouldn't be at all surprised if it's pitched in both directions and you have to deal with more than a 1/4" to the foot. 1/8" would normally be considered "flat" but it's not when you've got a "house on wheels". I doubt any of this has been considered in the planning stages. There's a reason we used to refer to the drawings as the funny papers. I've had to rework any number of architectural plans with the architect to make them work in reality. This from someone with a Bachelors of Architecture as well as 20 + years in construction trades of one form or another....

[walker]

Thanks DSW. Yes I am doing the install as well. Fortunately I was there when they were putting up the gunnite walls and was able to steer it a little and correct some bad errors before they actually shot it. The cabana weighs in at 12,000 pounds, split in two sections, so 6 grand apiece. It is supposed to hav a gear motor drive on it, but I have not seen the mechanical drawing yet. I have experienced the bus, and have found a nice indent in the asphalt to lie in while it drives past.

[DSW]

The kind of loads you are looking at and the word "gunnite" wants to make me run away as fast as I can. I doubt that indent in the asphalt is deep enough to cover your azz from the bus.

I've yet to see a gunnite guy who even knew what a level was. "Flat" wasn't even in their vocabulary.

In this case I might even want to think about doing the whole job on site. Set your flat bar straight and level, shim grout and secure as needed. Then mig the round stock in place using the anchored flat stock to help reduce warpage going from side to side alternating as you go down the length making corrections as you go to keep the whole thing as straight and level as possible.

The up side is that chances are you will get the least amount of distortion since the base is firmly " clamped" when you anchor it. ( be sure to let the grout dry before welding) The downside besides the need to work onsite and it's weather related issues, is that if something shifts radically for some reason. it will be harder to correct. If you are careful I don't see that as being a big issue however.

[walker]

The gunnite walls were engineered for the load, and I was able to check the level of the form before they shot it, so I am not so I don't have a huge amount of worry, just a lot.

[DSW]

The gunnite walls were engineered for the load, and I was able to check the level of the form before they shot it, so I am not so I don't have a huge amount of worry, just a lot.

Why do I have a vision of an ICBM launch pad concealed as a pool house for some reason now.

I did see a show years ago where someone had turned one of those decommisioned launch platforms out west into a house. I want to say it was possibly an older base since the roof slid aside so the launcher could be raised vertical rather than the deep vertical ICBM launch tubes. They could open and close the roof on the living room and since the house was all under ground, it was very energy efficient.