Selecting aluminum C-channel

[FlyFishn]

I am trying to find suitable aluminum for a rectangular frame (roughly 24" wide and 60" long). I am having trouble with my local metal supply places in that what I am spec'ing they can't get and they are not able to get me a catalog of what they can get so I can select from that.

I am hoping to get some pointers from the group here.

What I want is flat sided C channel that is 3" on the wide face and 1.5" on the shorter flanges, with a wall thickness of 3/32". The target grade is 6061-T6.

One supplier can get 3"x1.5" C channel like that with a 3/16" thickness in 6061. Another option would be a rectangular tube (closed tube) that is 3"x1.5" in 6063.

I did have both places mention that it might be possible to bend the parts on a brake, but 6061 wouldn't work.

I don't like the idea of forming over extruded stock of dimensions that would work. The idea is to do the fabrication myself, and not have a shop do it.

So that brings me to the post here - do you have any thoughts on how to go about selecting material size/type, or where I can source what I am after, that is going to be a "standard" or "universal" size?

Oddly enough, I did email a company that used a similar type of extrusion from what I could tell as to what I am looking for and the response I got from them was that they designed the extrusion for their own purposes so that stock was custom and proprietary to their company. That hits me a bit odd. Though, I used to deliver billets to an extrusion company so I know a bit about it and that custom extrusions are possible. However, if you go to Lowes and Home Depot, for example, they have various aluminum stock in 6-8 foot lengths. It would seem "standard" sizes/extrusion types exist - and I would surely be able to find something, proverbially, "off the shelf" that will work.

Is it the grade that is goofing up the selections? The size? The wall thickness?

[bassboy1]

Oddly enough, I did email a company that used a similar type of extrusion from what I could tell as to what I am looking for and the response I got from them was that they designed the extrusion for their own purposes so that stock was custom and proprietary to their company. That hits me a bit odd.

Not a bit odd, at all. Proprietary extrusions are very common, and inexpensive to make (assuming minimum orders of a couple thousand pounds or more). I personally own 2 proprietary extrusions.

Is it the grade that is goofing up the selections? The size? The wall thickness?

Yes.

It sounds like you are looking for an architectural extrusion (consistent wall thickness throughout the profile, and hard inside corners) vs an American standard or Aluminum Association structural channel (both styles of structural channels will have thicker flanges with thinner webs, also will have radius'd inside corners). Google those terms for pictures of the profile.

However, standard architectural shapes are pretty much always going to be 6063, so that's one thing goofing you up.

Secondly, you might find 3x1.5" architectural (it's not in any of the books I have, but some companies that don't publish books have other sizes), but it'll probably not be that thin. I've never seen .093" in anything bigger than 2x1".

Thirdly, if tube works, you should have no problem finding it in 6061, but it's going to be a .125" wall thickness. Same thing with channel, tube doesn't get made in .093" that large.

[FlyFishn]

It sounds like you are looking for an architectural extrusion (consistent wall thickness throughout the profile, and hard inside corners) vs an American standard or Aluminum Association structural channel (both styles of structural channels will have thicker flanges with thinner webs, also will have radius'd inside corners). Google those terms for pictures of the profile.

Thank you for the reply. That gets me some traction here.

It appears 6063 is where I am going to have the most luck with the architectural extrusions. I am hoping in an assembled frame 6063 can take various dynamic loading and vibration scenarios - namely the joints. Overall material strength for the main frame is a moot point I think - even 2"x1"x3/32" should be adequate, in an assembled frame. But the joints are the question. Reinforcement/gussetting would be easy. Aside from the main frame being C channel, extra bracing would be angle. Welding a strip of angle in a corner, even outside the frame, of the main C channel frame would be pretty easy if need-be = distribute the forces on the frame over larger weld area between the joint in the C channel itself and the sides of the angle, though the HAZ on the C channel frame would increase with welding the angle in place. So the extra bracing of the angle might be a moot point for distributing frame forces. Either way, the extra thickness the angle would provide to a corner would give the corner more impact resistance (not that impact there would be routine or desired, but just-in-case).

[bassboy1]

Thank you for the reply. That gets me some traction here.

It appears 6063 is where I am going to have the most luck with the architectural extrusions. I am hoping in an assembled frame 6063 can take various dynamic loading and vibration scenarios - namely the joints. Overall material strength for the main frame is a moot point I think - even 2"x1"x3/32" should be adequate, in an assembled frame. But the joints are the question. Reinforcement/gussetting would be easy. Aside from the main frame being C channel, extra bracing would be angle. Welding a strip of angle in a corner, even outside the frame, of the main C channel frame would be pretty easy if need-be = distribute the forces on the frame over larger weld area between the joint in the C channel itself and the sides of the angle, though the HAZ on the C channel frame would increase with welding the angle in place. So the extra bracing of the angle might be a moot point for distributing frame forces. Either way, the extra thickness the angle would provide to a corner would give the corner more impact resistance (not that impact there would be routine or desired, but just-in-case).

I'll warn you that the 2x1x.093 might still be tough. I use a few hundred sticks a year of 2x1x.125 channel, and once or twice asked about the .093", as it's listed in the book, but have always been shot down. There are some sizes that are 'available,' meaning the die exists for them, and they are in a stock list, but no one actually keeps it on hand, so you need to order enough for a minimum mill run of it. I haven't actually tried chasing that down beyond a quick ask, so you might have better luck.

What's the reasoning for the thinner wall? Any reason you can't use .125?

[FlyFishn]

The project is a trailer for bicycling. If you are familiar with bike touring - that is the application - a place to haul gear around instead of bags/panniers on the bike. The frame is going to have a box on top - which is why the C channel is preferable (the flanges make it easy to attach the box to it). The overall idea of the frame is to give rigidity to the box, as well as a means to attach other support members that will take more concentrated forces - like the brackets for the axles (which will carry around 90% of the rolling weight, the other 10% or so being on the hitch) and the hitch bar. Speaking of axles - I am going after a design from a fellow bike traveler I rode with for 3 days recently that uses regular bike hubs/axles that are supported on both sides of the axles, not just the inside facing the trailer. For the inside and outside "rails", if you will, that hold the axle for the wheel they will be 1/4" thick angle - I am thinking 1.5" face. Using allthread to support the outer rails would make it easy to assemble and adjust/space for the axle widths.

So with respect to the C channel thickness - by giving rigidity to the box and other parts thicker that take the more concentrated loads/forces - thicker metal means more weight where it isn't needed.

Below is a link to a picture of the type of frame I am after. If you look at the outside rectangle construction and welded joints - that is exactly what I'm after. Although, this frame might be too beefy. As to the rest of the build on this one - there are a few things I don't like so as far as using this as an exact model - don't take the pictorial as exactly that, just the outside rectangle frame of the C channel. As far as the corner welds on this - I like how the builder blended the C channel together so that the short front and back pieces have the flanges cut back to allow the side frame rails to take their place, then all the faces are welded shut. Thats exactly how I want to make it.

https://www.flickr.com/photos/monkey...7617446793100/

[ezduzit]

The 3/32" wall thickness is non-standard. Use 1/8" wall. Besides channel you could rip square tube.

[bassboy1]

What is the box going to be made of?

[ezduzit]

...I am having trouble with my local metal supply places in that what I am spec'ing they can't get...What I want is flat sided C channel that is 3" on the wide face and 1.5" on the shorter flanges, with a wall thickness of 3/32"...

One essential element of good design is to first choose a material that is actually available. Anything else is futile.

[FlyFishn]

The 3/32" wall thickness is non-standard. Use 1/8" wall. Besides channel you could rip square tube.

Ripping is a possibility... but I had to do that for a larger fab project in 2019 ripping 3/16" angle to weld in to square tubing because I couldn't get a stock size the right size and it was a major PITA. That was over a week of time it seemed.

Depending on how easy the aluminum is to cut, I have a carbide metal blade for my circular saw that I may be able to put on my table saw. That might make ripping a piece of cake. We'll see.

[FlyFishn]

What is the box going to be made of?

Aluminum - something around 3/32" (11 to 13 gauge I think, looks like the thickness of aluminum sheet is thinner per gauge than steel so what ever lies around 3/32"). The sheet would be reinforced with angle on the edges.

[bassboy1]

Aluminum - something around 3/32" (11 to 13 gauge I think, looks like the thickness of aluminum sheet is thinner per gauge than steel so what ever lies around 3/32"). The sheet would be reinforced with angle on the edges.

.090" would be the closest size sheet. Aluminum gauges do technically exist (and differ from steel), but they are never used.

Skip the channel frame. Your box formed out of .090 sheet will be way stronger than the frame would ever think of being. You would be fine with .063", as long as the box was more than a couple inches tall. Use an 8" long or so piece of 1/8" wall structural angle lengthwise on each side to spread the axle load.

Press brake the sides of the box, and turn a small flange in on the tops, then outside corner weld on your ends. I know you're trying to avoid outside forming, but this is one of the times it behooves you to bite the bullet and do it right.

[OPUS FERRO]

ezduzit

One essential element of good design is to first choose a
material that is actually available. Anything else is futile.

Shhh - Your posit is why I have been able to urinate
on Architects and Engineers for decades . . .

Bury this card back in the deck . . .

hth


Opus



.

[FlyFishn]

.090" would be the closest size sheet. Aluminum gauges do technically exist (and differ from steel), but they are never used.

Skip the channel frame. Your box formed out of .090 sheet will be way stronger than the frame would ever think of being. You would be fine with .063", as long as the box was more than a couple inches tall. Use an 8" long or so piece of 1/8" wall structural angle lengthwise on each side to spread the axle load.

Press brake the sides of the box, and turn a small flange in on the tops, then outside corner weld on your ends. I know you're trying to avoid outside forming, but this is one of the times it behooves you to bite the bullet and do it right.

I do have a small brake - one from harbor freight. I want to say it is around a 30" width. So it is conceivable I could get a run of sheet that was 24" wide and as long as I would need to wrap all 4 sides of the box then bend it to a box. I don't have the ability to do a flange, though. Maybe small angle could be used instead?

My idea for a lid was, in a round about way, have a lid on a hinge that would use foam tape molding (think sliding window seal foam tape) that presses against a flange on the box body. Off the top of my head, without drawing up an actual design, what comes to mind is a small (3/4" or so face) angle all the way around the inside of the box on the top edge. Then have the lid over hang the box top edge with a flange that hangs down (same angle idea could be used here potentially).

I can check and see if some buddies that also do some metalwork know of a fingerstock brake that might be around... that would be nice.

As to specifically what you had in mind for press braking the sides of the box - do you have a pictorial? Or can you describe it?

If I used the continuous brake I have to form the box my thoughts are to have the front or back the seam, as opposed to have the seam on a corner. Would that make sense?

[OPUS FERRO]

FlyFishn

Spin your Telescope - and, reconsider Sage Design . . .

Who first tied - the Raggedy *** Coachman - and what
water's did it slay . . .

hth


Opus



.

[FlyFishn]

FlyFishn

Spin your Telescope - and, reconsider Sage Design . . .

Who first tied - the Raggedy *** Coachman - and what
water's did it slay . . .

hth


Opus



.

I've read over what you typed 4 times and I can't decipher it. Can you explain in better wording? Thanks.

[Kevin Morin]

Fly, if the frame (above discussed) was intended to "support" a welded aluminum box? then it's completely redundant; as Bassboy has mentioned.

The sides of a box, pressed to their sizes, are deeper by far than the few inches of channel you've proposed. So the section modulus of a 0.090" (or so) sheet that is a foot tall (with pressed edges as flanges) is astronomically greater than a short channel- even 0.187" wall!

Just make the box w/ flanged top and bottom edges and sleeve the axle into the sides with a doubler and you'll have more strength, less overall wt. and better fab time and a cleaner finished product.

cheers,
Kevin Morin
Kenai, AK

[OPUS FERRO]

FlyFishn

I've read over what you typed 4 times and I can't decipher it.
Can you explain in better wording? Thanks.

Thanks for your civil discourse - reread 'your entire thread' for
comprehension [4 times +] - the answer is apparent . . .

[Your design may be crap . . . ?]

Fish bite 'on known feed' - don't waste your time re-engineering
our [over] engineered world . . .

[Build with what you can get - not what you want] . . .

Where - is your favorite water/and fly . . .

hth


Opus



.

[bassboy1]

My idea for a lid was, in a round about way, have a lid on a hinge that would use foam tape molding (think sliding window seal foam tape) that presses against a flange on the box body. Off the top of my head, without drawing up an actual design, what comes to mind is a small (3/4" or so face) angle all the way around the inside of the box on the top edge. Then have the lid over hang the box top edge with a flange that hangs down (same angle idea could be used here potentially).

I can check and see if some buddies that also do some metalwork know of a fingerstock brake that might be around... that would be nice.

As to specifically what you had in mind for press braking the sides of the box - do you have a pictorial? Or can you describe it?

You're on the right track for the box with a flange on the top inside to hold a gasket (with an overhanging flanged lid), but get rid of the angle, and form it out of the sheet.

What you need to do is form the bottom, the two long sides, and the top flanges out of one piece of material. This will be a total of 4 bends on this piece, and you'll need a 5' brake to accomplish this. The end result will look like U with the addition of inside flanges, that is 5' long.

Then, your ends will be 2 separate pieces, each with the flange formed at the top. No need for a finger brake for this portion of the project.

The goal is to bend the longest seams and weld around the end. This reduces welding time, but more importantly, minimizes distortion that you'll otherwise deal with on a 5' seam.

Your overhanging lid is where the finger brake would be most beneficial, but not the end of the world to have them bend the long sides with a straight brake, then weld on the short side flanges.

Where are you located?

[Broccoli1]

Search craigs list for an aluminum ladder.

20 bux all day long out here.

[FlyFishn]

You're on the right track for the box with a flange on the top inside to hold a gasket (with an overhanging flanged lid), but get rid of the angle, and form it out of the sheet.

What you need to do is form the bottom, the two long sides, and the top flanges out of one piece of material. This will be a total of 4 bends on this piece, and you'll need a 5' brake to accomplish this. The end result will look like U with the addition of inside flanges, that is 5' long.

Then, your ends will be 2 separate pieces, each with the flange formed at the top. No need for a finger brake for this portion of the project.

The goal is to bend the longest seams and weld around the end. This reduces welding time, but more importantly, minimizes distortion that you'll otherwise deal with on a 5' seam.

Your overhanging lid is where the finger brake would be most beneficial, but not the end of the world to have them bend the long sides with a straight brake, then weld on the short side flanges.

Where are you located?

Thanks for the details. I will hit the drawing board and see what happens. Speaking of drawing board... when I was in college I took some industrial design courses and ended up doing a lot of hand drafting. My dad is an architect and had a real nice oak drafting table with a drafting machine - the big articulating arm straight edge. So I had that set up in my room to work on my projects with. That was fun working with dads old-school stuff! Sadly, I took it apart and took it back to keep over there and when he was down-sizing houses it ended up getting tossed out or sold in a garage sale. If I had space to hang on to it I would have really loved to have kept that. Though, I do have a lap top drafting table/machine that I got prior to setting dads up. Its just not the same as the big heavy oak table and machine - think the size of a piano.

In any event, I'm in Ohio. I see you are in GA. We're too far away.

As to the welding and distortion - that doesn't have to be. The seams don't need to entirely be welded, so long as they can be sealed. That should be easy with some sealant, but I agree sealing with the metal (either the bends you refer to or welds) would be better if possible to achieve.

[William McCormick]

I am trying to find suitable aluminum for a rectangular frame (roughly 24" wide and 60" long). I am having trouble with my local metal supply places in that what I am spec'ing they can't get and they are not able to get me a catalog of what they can get so I can select from that.

I am hoping to get some pointers from the group here.

What I want is flat sided C channel that is 3" on the wide face and 1.5" on the shorter flanges, with a wall thickness of 3/32". The target grade is 6061-T6.

One supplier can get 3"x1.5" C channel like that with a 3/16" thickness in 6061. Another option would be a rectangular tube (closed tube) that is 3"x1.5" in 6063.

I did have both places mention that it might be possible to bend the parts on a brake, but 6061 wouldn't work.

I don't like the idea of forming over extruded stock of dimensions that would work. The idea is to do the fabrication myself, and not have a shop do it.

So that brings me to the post here - do you have any thoughts on how to go about selecting material size/type, or where I can source what I am after, that is going to be a "standard" or "universal" size?

Oddly enough, I did email a company that used a similar type of extrusion from what I could tell as to what I am looking for and the response I got from them was that they designed the extrusion for their own purposes so that stock was custom and proprietary to their company. That hits me a bit odd. Though, I used to deliver billets to an extrusion company so I know a bit about it and that custom extrusions are possible. However, if you go to Lowes and Home Depot, for example, they have various aluminum stock in 6-8 foot lengths. It would seem "standard" sizes/extrusion types exist - and I would surely be able to find something, proverbially, "off the shelf" that will work.

Is it the grade that is goofing up the selections? The size? The wall thickness?

6061-T3 will bend a ninety. 6061-T0 will certainly bend a ninety.
5052-H-32 will bend a ninety that is what everyone uses for marine gas tanks. We live on an Island so we see a lot of that.
The term for C-channel with un-tapered legs was architectural C-channel, with a tapper was structural C-channel.

Available in my area readily is 6063-T52 C-Channel it comes in 16-foot lengths 3-inch face and 1.5-inch legs and is 1/8" thick. A lot of the extrusion is this material. It used to be more 6061-material. But now mostly 6063.

Sincerely,

William McCormick

[William McCormick]

I am trying to find suitable aluminum for a rectangular frame (roughly 24" wide and 60" long). I am having trouble with my local metal supply places in that what I am spec'ing they can't get and they are not able to get me a catalog of what they can get so I can select from that.

I am hoping to get some pointers from the group here.

What I want is flat sided C channel that is 3" on the wide face and 1.5" on the shorter flanges, with a wall thickness of 3/32". The target grade is 6061-T6.

One supplier can get 3"x1.5" C channel like that with a 3/16" thickness in 6061. Another option would be a rectangular tube (closed tube) that is 3"x1.5" in 6063.

I did have both places mention that it might be possible to bend the parts on a brake, but 6061 wouldn't work.

I don't like the idea of forming over extruded stock of dimensions that would work. The idea is to do the fabrication myself, and not have a shop do it.

So that brings me to the post here - do you have any thoughts on how to go about selecting material size/type, or where I can source what I am after, that is going to be a "standard" or "universal" size?

Oddly enough, I did email a company that used a similar type of extrusion from what I could tell as to what I am looking for and the response I got from them was that they designed the extrusion for their own purposes so that stock was custom and proprietary to their company. That hits me a bit odd. Though, I used to deliver billets to an extrusion company so I know a bit about it and that custom extrusions are possible. However, if you go to Lowes and Home Depot, for example, they have various aluminum stock in 6-8 foot lengths. It would seem "standard" sizes/extrusion types exist - and I would surely be able to find something, proverbially, "off the shelf" that will work.

Is it the grade that is goofing up the selections? The size? The wall thickness?

Remember though if you are going to bend it from a flat 1/8" sheet that you have to take a quarter off for the face and 1/8" off for each leg. So your cut size for a 3" C-channel with 1.5"legs, is going to be 6 - 1/2" = 5 1/2"s to allow for growth over the bends.

If you use 3/32 which is delivered as 0.090" material you have to take off for that thickness. So you would have a cut size of Approximately 5 5/8". When you mark in from the legs for the bend line you just make the mark Approximately 3/32" 0r 0.090" less than 1.5. If you check the distance between the two bends for the face it should be Approximately 2 13/16" or 2.82"

I have seen really brilliant guys screw up a lot of material because they just didn't know that the metal grows over the bend lines.

Sincerely,

William McCormick

[FlyFishn]

.090" would be the closest size sheet. Aluminum gauges do technically exist (and differ from steel), but they are never used.

Skip the channel frame. Your box formed out of .090 sheet will be way stronger than the frame would ever think of being. You would be fine with .063", as long as the box was more than a couple inches tall. Use an 8" long or so piece of 1/8" wall structural angle lengthwise on each side to spread the axle load.

Press brake the sides of the box, and turn a small flange in on the tops, then outside corner weld on your ends. I know you're trying to avoid outside forming, but this is one of the times it behooves you to bite the bullet and do it right.

I am revisiting this project and designing.

I may have access to a Grizzly 0542 pan and box brake:
https://www.grizzly.com/products/gri...12-gauge/g0542

I haven't done a whole lot of sheet metal work before but I gather this would make the bends you refer to a lot easier? Thoughts on what I might be able to expect for bending vs what limitations it might have?

[bassboy1]

I am revisiting this project and designing.

I may have access to a Grizzly 0542 pan and box brake:
https://www.grizzly.com/products/gri...12-gauge/g0542

I haven't done a whole lot of sheet metal work before but I gather this would make the bends you refer to a lot easier? Thoughts on what I might be able to expect for bending vs what limitations it might have?

Won't help much for bending a 60" length, but if you decreased the length of the trailer to 48", it would do fine for what you need.

Have you thought about asking the metal suppliers if they can shear and bend the unit out of sheet. In my neck of the woods, you'd be looking at 35 - 50 bucks to have those parts sheared and bent.