how to line up a pipe to weld?

[tarbellb]

heres the scenario.

im welding up a ladder using 1/8" x 3" flat bar for verticals. and then using 1"od x 1/8" pipe for the rungs.

what is the best or common or "i found this to work well" methods used to center the pipe perfectly for welding?

meaning, how do you hit your center of 3" AND vertical marks WITHOUT scribing all over the work piece?

for now i found this method to work the best:

1) use center punch to center mark the circumference of the rung

2) go back and use a hole cutting drill bit with centering bit to mark the circumference of the hole. not going all the way through the work piece though!

 

[GarageEnvy]

I'm guessing you are welding the pipe onto the face of the flat bar rather than running the pipe through the flat bar. Otherwise I would have suggested drilling both sides at once. I usually use a vise clamped/bolted to my drill press when I want things in line.

 

[dittle fart around]

I would go all the way through the flat bar. That would give you two surfaces to weld to. Making centering easier and the welded connection stronger.

 

[kbs2244]

If he goes all the way through, will he have to plug the ends of the pipe?

 

[MoonRise]

Make sure you paint/coat, knurl, dimple, or otherwise treat the rungs to "minimize slipping". OSHA requirements and general good practice.

Also note the rung-to-rung spacing requirements (depending on the application and possible exemptions to the general requirements, but 12 inch OC is usually fine and 'in-spec').

Drilling through the uprights certainly does give you some self-jigging and centering capabilities, but it sure would add a lot of machining time to the job!

Instead of marking each and every rung placement, maybe spend some up-front time and make a centering/locating/spacing jig of some sort. A couple of V-blocks for each rung and then some spacing blocks between rungs/blocks and then go to town. Two sets of V-blocks spaced the 'appropriate distance apart (12 inches?) and you can index the next rung off of the previous rung (that you just tacked into place). Just have to 'locate' the first rung position. Index the height/centering of the V-blocks off of the work/welding table so that the rungs are centered on the uprights side-to-side. Etc, etc, etc.

 

[Grumpy365]

I am no fabricator, BUT I would take my pipe rung, square it up one way, tack it, square it the other way, tack it, check square again all the way around, weld it.

 

[Spectre32]

Well you can take a piece of TIG wire like a 1/16 or a 3/32 and just use that to set your gap between the sides of the hole. That is kinda dependent upon how tight your holes are drilled. If you are setup for a close fit then I would just line them up however you want and then just do a fillet weld around the outside diameter. I would use filler metal as an autogenous weld would probably be sufficent but having the additional strength would not hurt anything. I would probably just pick one side of the hole, **** the rod to it tack it in, and then just weld it up.

 

[tarbellb]

Make sure you paint/coat, knurl, dimple, or otherwise treat the rungs to "minimize slipping". OSHA requirements and general good practice.

Also note the rung-to-rung spacing requirements (depending on the application and possible exemptions to the general requirements, but 12 inch OC is usually fine and 'in-spec').

Drilling through the uprights certainly does give you some self-jigging and centering capabilities, but it sure would add a lot of machining time to the job!

Instead of marking each and every rung placement, maybe spend some up-front time and make a centering/locating/spacing jig of some sort. A couple of V-blocks for each rung and then some spacing blocks between rungs/blocks and then go to town. Two sets of V-blocks spaced the 'appropriate distance apart (12 inches?) and you can index the next rung off of the previous rung (that you just tacked into place). Just have to 'locate' the first rung position. Index the height/centering of the V-blocks off of the work/welding table so that the rungs are centered on the uprights side-to-side. Etc, etc, etc.

i like your idea of jigging it up. i dont own a set of v-blocks but could come up with my own solution for this. thanks

as for drilling all the way through, i didnt think about that. a few issues though, i dont have a accurate enough hole saw to do a clean hole, and capping may be a issue with the client?

thanks for the responses.

im assuming then there is no tool/transfer/marking device to mark and locate the outside of the pipe on the flat bar?

 

[GarageEnvy]

You could always dado out a block of wood (or tack strips on the side) and put two holes in it. Mark one, move the block over to the next hole and mark. It would keep things centered and your spacing the same. It's just a bit more setup time for a single ladder. I'm curious about the choice of flat bar for the outside. Is this ladder going to be mounted on something? I think there could be a fair amount of lateral sway if it's freestanding. Some 1"x3" tubing that you only drilled through one face of might solve a couple of problems. I didn't mention it initially because I was trying to just answer the question and not redesign the whole project.

 

[Spectre32]

Oh.... Your not drilling through... I guess I was under the impression you were(I didn’t read the post to well at first glance)... Well that makes it a little different. You could "dish” the flat bar but that would require you to machine out little circles. That solves the cap issue and allows you to main a smooth outer surface. To be honest, if your making this ladder for actual working purposes and not some acetic reason, you probably want the pipe to run through the flat bar. That would allow for the most force to be transfers through this member, because if not... then all of the weight will fall on the weld joint itself. It would be pretty hard to get a quality weld in that situation while maintaining a decent looking weld…which I assume is important as if it wasn't he could have bought a Werner by now. So I would advise you to weld on both sides of the flatbar. If you had the hole to a interference style fit I would use the hole to get your spacing correct. Tack it all up and then weld on the outside and inside of the rung. You could blend the outside but any material you remove for cosmetic purposes is to some degree affecting the strength of that particular joint, but since your through the flat bar your not loosing anything from a structural standpoint. You could make light gauge caps for the pipe and weld them on and then continue on with that I outlined or you could just use solid bar. You could decrease the size as well as it will be just as strong for a lesser OD size.

 

[pro machine Engineering]

make you a small jig out of wood or metal that will line up the next rung that needs welded. Make for certain your first run is square with the world. Then build off it with the jig. moving the jig to the next rung as you move up the ladder. I would only tack them in place until you get the last one in and it can be checked over good. Lot easier to move a tacked piece than one that has been welded. If the jig is squared and true it and the first rung is squared it should be a piece of cake.

 

[zer01]

What is this ladder going to be used for? Are you going to brace the sides with anything? I may be wrong but that flat stock would not give me much confidence for the sides of a ladder.

 

[tarbellb]

to answer the intended purpose question.

it will be a light duty use rolling library type ladder. being installed in a high-end loft.

i have also questioned the strength of the vertical sides only being 1/8". but i figure with all the 1" pipe rungs bracing, it should hold.

most of the forces on this ladder will be down, and some leaning into the wall. only a real world test will tell me if it will actually hold up?

like this- but more industrial

 

[tarbellb]

oh. im not having issues with marking the piece centered and spaced... just after when im placing the pipe on just a centerpunched mark, not being able to see or center it.

 

[pro machine Engineering]

I think where you are going to get into trouble is once welded. The heat is going to want to twist the ladder and tweek it out of straight

 

[Milton Shaw]

I also don't think the flat bar is strong enough in this application. All ladders I have seen have some type of "I" beam or "H" beam for the side structures to keep them from bending. You could use box tubing and drill through both sides and get the structural strength that a ladder needs. It looks like you are using something like a 3" wide strip of 14 gauge for the side pieces. Those have almost no strength in length wise compression they will fold, and the whole ladder would fold.

 

[tarbellb]

I think where you are going to get into trouble is once welded. The heat is going to want to twist the ladder and tweek it out of straight

ahhhh yes! damn. i think your right with the warping from to much heat.
what could i do?

clamp the whole piece while do small welding sessions?

Milton Shaw- please read the original post for exact specs on the pieces used, please dont guess at what it is and then make suggestions based off that guess

 

[Sureshot]

I would use 1"x2" or 1"x3" rectangular tubing. Drill one side only.

Make a jig the inside width and distance between rungs out of wood. So it would be say 16" wide by 12" long and then you can clamp your sides in place while welding. If using the flat cut some 1/2" plywood 20" or so then add some kind of layer(s) the right spacing between steps. Stands your backside off and spaces your steps so they are all the same.

I would be very surprised if the 1/8" doesn't feel very unstable and not a very comfortable grip for the hands.

You will also be able to use very light tubing so as not to add any weight.
The rectangular tubing will look much nicer and a simple bead around the inside will be plenty strong.

 

[Spectre32]

ahhhh yes! damn. i think your right with the warping from to much heat.
what could i do?

clamp the whole piece while do small welding sessions?

Milton Shaw- please read the original post for exact specs on the pieces used, please dont guess at what it is and then make suggestions based off that guess

Watch your heat input and build the whole thing at once. Tack it all together and then start welding rungs from opposite ends to allow the heat to dissipate

 

[tarbellb]

im am committed to using the 1/8" x 3" bar right now. the idea was to keep it as light as possible + clean minimal look. the entire ladder will be suspended off the front of a wall cabinet that cantilevers 18" from the wall. so weight is a concern.

so is safety, i will be interested to see if the 1/8" bar will work or not?

hoping to weld it up tomorrow or friday, will post results.

 

[Altec]

The 1/8 flat bar is plenty. Think of it like wrench. All your force is applied to the wide section, not the thin section, and for a light duty indoor ladder, this is plenty enough.

If it was my job, I would center punch where I want the pipe at, then using a square, mark half the OD off each side of the center punch marker with soap stone. So I end up with something that looks like a white square shape, with a dot in the center. Then I can take the pipe, center it in the square, and tack it. Easy.

The great thing about soap stone is it isn't effected by heat, so you won't lose your marks... Doesn't give the most precise edge, but it is for a ladder...

 

[knucklehead]

it wont hold up, it will certainly wobble to the sides as you climb it.
another thought is to add some oak stringers to the outsides of the flat bar to beef them up & provide a better hand grip.

 

[Altec]

I highly doubt the ladder will sway much, if at all given that it is a reasonable length. 8-10' will be fine. The 1" tubing will keep it from swaying unless he is trying to do a longer ladder then reasonable for the material he picked. To get any sway on a ladder in the 10' range would involve ripping his welds off.

 

[steel 35]

I **** at math but I would have laid the 1" tube down then stood up the sides and laid the rungs on it.

 

[boohocky]

You can't use v-blocks? Idk if I totally understand here, but when welding something true and round, I usually just use v-blocks and clamp them to the work pieces.

 

[zer01]

I understand where the intended forces are going to be theoretically applied but any movement side to side can and will bend that steel fairly easily. That length of flat stock will not hold up to regular use as a ladder. Not trying to start anything, it will need more side support. The rings will tie the sides together which will provide some added strength but 1/8th inch steel is still not strong enough especially since it will be a moving ladder.

 

[Strouty]

I work on towers and they make ladders similar to yours, the sides are usually 1/4" but they are way overkill. I have seen them bend, but only after someone does something stupid. Here is a diagram with them showing size. Notice how the heavy duty gets larger rungs and wider flat bar, but not thicker. I think the 3" wide will save you, plus those pipes welded to the bar will stiffen things up a lot. Do you have a large metal table? If you did, you could tack weld the sides to it and then weld in the rungs. Maybe make a jig, we did that when we made some of our tower ladders.

 

[srmofo]

Here my idea for a jig.

Support your verticals, clamp and square them to each other, Install the first rung nice and true, use this jig (one on each side of the rung)to keep the remaining rungs true to the first rung.

 

[Strouty]

He should also make something to keep the two sides from creating a diamond while welding. When you weld tack it together then alternate where you weld so you don't put too much heat in one spot.

 

[Altec]

I understand where the intended forces are going to be theoretically applied but any movement side to side can and will bend that steel fairly easily. That length of flat stock will not hold up to regular use as a ladder. Not trying to start anything, it will need more side support. The rings will tie the sides together which will provide some added strength but 1/8th inch steel is still not strong enough especially since it will be a moving ladder.

The only way for it to move is to stretch the steel, or rip his welds out. It is as simple as that. Now if a proper size ladder can stretch 3/8" of steel per-side, or rip 3.14" of welds per-side per-rung, then he must be having elephants looking for some good reading material.

We aren't talking about just one piece of 1/8" steel bar. I can bend a ladder length piece of 1/8" steel easily. However two of these tied together with 1" tube? No way.

Seems like Strouty has the experience first hand in a industrial environment. His opinion should be all that is needed.

 

[Strouty]

We aren't talking about just one piece of 1/8" steel bar. I can bend a ladder length piece of 1/8" steel easily. However two of these tied together with 1" tube? No way.

Seems like Strouty has the experience first hand in a industrial environment. His opinion should be all that is needed.

I agree with both of these comments!

 

[zer01]

My bad, thought my experience and knowledge was worth something here. I stand corrected. Good luck with your project.

 

[ujmchris]

My idea would be this:
Take 2 pieces of your flat stock and cut them about 6-8" longer than your anticipated run spacing. Take 2 pieces of angle iron (1"?) and cut them .25" shorter than your rung length. Notch 2 "V"s into the flat stock where the rungs will go. Weld the angle iron between the flat stock at the appropriate height. Hopefully the picture will help explain it.

Now you can clamp your flat stock to the outside of the flat stock on the jig. Lay your first rung in the angle iron. You can tack it in 2 places within the "V" notch. Lay in your second rung in the 2nd angle iron and tack it, move the jig down and continue. Then you can remove it and finish welding. If everything is square with the jig, this will accurately space and locate the rungs, and keep the sides square.

 

[Altec]

That is a good fixture idea! Although I may want to take a couple extra strips of flat bar, and weld them going in the same direction as the channel on the underside of the side pieces, having them stick out about a inch on each side. That way I don't have to rely on my work surface to get the height of the sides set right.

 

[D.J.]

Kinda late now but all firefighter textbooks say standard rung spacing is 14" just a note and my $.02.

 

[ujmchris]

That is a good fixture idea! Although I may want to take a couple extra strips of flat bar, and weld them going in the same direction as the channel on the underside of the side pieces, having them stick out about a inch on each side. That way I don't have to rely on my work surface to get the height of the sides set right.

Great idea. I thought about something like that, but just envisioned the jig sitting on my (mostly) flat welding table.

 

[Zengineer]

If the ladder is hanging (side bars in pure tension) you likely won't have issues.

If it's resting on the floor, you have a column (and compression loading) and buckling must be considered. 1/4" sides may be overkill, but they are that much thicker to resist buckling... the same reason most ladders are box or C-channel; resistance to buckling.

1/8" sides are suspect if it's not a hanging ladder...

 

[Griff93]

You can mark these pretty accurately if you have a scribe, center punch, adjustable calipers, and a steel rule. Figure out where you want the center of the tube to be and mark it with a center punch. Take the adjustable calipers and set them to the radius of the desired tube size. Put one end of the caliper in the center punched hole and rotate them around. This will give you the layout of the piece of tubing based off of center.

 

[zer01]

If the ladder is hanging (side bars in pure tension) you likely won't have issues.

If it's resting on the floor, you have a column (and compression loading) and buckling must be considered. 1/4" sides may be overkill, but they are that much thicker to resist buckling... the same reason most ladders are box or C-channel; resistance to buckling.

1/8" sides are suspect if it's not a hanging ladder...

 

[tarbellb]

wow, this really took off! thanks for all your helpful input, including you zer01.

i think the materials will work, but only real world testing will tell.

the rungs are spaced a very accurate 11.5" center to center.

the reason i picked 1/8" flat bar is for weight and it matches other materials in the project, i spec'd 3/16" but there is a huge difference in both weight and beef. it seemed to beefy for this application.

this is a library ladder, for a artist, who doesnt read. he literally said "i want the ladder cause it just makes a place look classy" ha. it wont get much use. i will post pics of the final project installed. but heres the carriage system that will support the ladder and roll on 3/16"x3" flat bar on its edge. cantilevered 18". that should also get some of you stirred up as to if it will work and why it will/wont