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05-14-2010, 09:21 AM #1
SS u-channel availability/problems ???
I am going round and round with a problem for a large facade installation.
I need 12,000 feet of 1" X 1/2" SS u-channel, 1/8" thick material.
The channels will be drilled (a total of about 60,000 holes in a repetitive pattern) and then assembled into a 1" X 1" square tube (in 10' sections) and then I will have the joy to put 300 of these 10' assembled pieces up there.
Commercial U-channel in 316 is either unavailable or sooo expensive that it seems cheaper to have the u-channels roll formed, which isn't free either.
For a prototype we used 1" square tubing and cut it in half, that was the cheapest we came up with.
My laser guy can't slit it for us because he says, he would have to do one side and when he turns it over it is unstable and he couldn't do the second side.
What to do?? Drill all these holes (a problem all in itself!) and then bandsaw the pieces in half?? At least band sawing, unlike lasering, cuts thru the whole tube at once.
Any suggestions for a desperate guy??
05-14-2010, 10:04 AM #2
Lemme guess- an architect designed this?
Why does it need to be 1/8" thick? 1/8" stainess is strong enough to hang cars off of- I would get a quote from somebody to bend 10 foot sections of 14 gage or even 16 gage on a ten foot press brake.
Stainless, bent into a U shape, is really really stiff. Even 16 gage is very strong and rigid when bent.
I do a lot of this type of decorative work in stainless, literally tons and tons of it over the last 15 years. You cant let somebody else tell you in advance what it will cost- you need to bid it appropriately.
Materials cost for stainless is generally at least 3 times mild.
Final cost, including fabrication, should be 2 times mild.
YEP, double, at the very least.
every single part of dealing with stainless costs more. It goes thru more, and more expensive, tooling, consumables, welding supplies, sandpaper, drill bits, and everything else.
There is no magic supplier that is willing to sell you stainless steel for less than market price. And market price for basic shapes, in the most common forms, is over $2.50 a pound right now, all though some shapes are as much as four bucks.
Add in custom processing, and you immediately are talking real money, as you have found out.
Either they have enough money to pay to do it right, or you are a charity. I suppose if your last name is Gates or Buffett, you can afford to do a job like this for less than cost, but I sure cant.
Alternatively, price it in galvanized, have the stuff punched first, then sheared and bent on a press brake. Immediate 2/3 savings in material costs.
There is no cheap way to do what you want.
Yes, you can plasma, waterjet, or laser cut the square tube. You need to find a shop that will work with you, to make jigs to hold it for the second cut, after the first one is made. Some kind of shim/clamp combo that holds the first cut spaced apart the right distance, but clamped together, so the second cut can be made. Expect handling costs to double the normal cut charges.
I have done slits in square tubing before with my plasma table- you need to make special clamping jigs so the stuff doesnt move around.
Custom rolling channel costs what it costs- stainless wears out dies, and requires twice the machine that the equivalent mild steel takes, for the same thickness. more money.
Even bending it on a press brake costs more. Derate by at least two gages for stainless, which means you need a pretty big brake to bend 1/8". Plus, 1/8" doesnt like to be bent that tight- 1" square if very small for that thickness of material. Of course it can be done- it just costs, you guessed it, more money.
05-14-2010, 11:23 AM #3
This is just huge supposition, because we don't know what the "hole pattern" actually entails, but...
1. Have you checked out SS unistrut? Even if it's a custom run, it might be enough to get your attention. They can do holes, too. Are they where you want? Who knows...
2. Have you considered starting with 1x1 square 10', and spending your time and money on the hole drilling side of things? It seems you start with channel because of the holes. Could water jet or laser do the holes in finished 1x1 square? It seems like you'd never be more than 5' away from the hole. Could you send a CNC mirror up the 1x1 to bounce the laser to where it needs to be?
Note, I could be full o' crap, too...
05-14-2010, 11:56 AM #4
"(a total of about 60,000 holes "
With that many holes..... start with a 12 ga....... SHOTGUN
05-14-2010, 12:20 PM #5
2. Have you considered starting with 1x1 square 10', and spending your time and money on the hole drilling side of things?
Chip, I would do it that way. There are two or three holes every few inches, and they should be drilled first.
But in the end two halves are needed because they need to be electrically insulated from each other.
Of course I started with the U-channel that I need, but I think the approach with a 1"x1" square tube is cheaper (it seems more readily available), even if you factor in the cost of slitting and/or sawing it open.
And yes, it seems the wall thickness is needed, otherwise the two halves twist and shift with regards to each other, blame the wicked wind in downtown SF.
05-14-2010, 06:13 PM #6
Unistrut is available in SS, and most of their stuff is available undrilled. Since it has a little crimp on the edge, extruded plastic insulators could be made to fit and join the parts. Whether its ultimate profile and size will pass muster is up the the architect... I don't think the small stuff is exactly 1".
The electrical insulation material may hold the key to your efficiency. If it totally encloses the cut edge, remaining burrs may be beneficial to retention. That would make the cutting method selection easier.
Since they're apparently using the structure as conductors for the lighted sign/jumbo display board (just a guess), or some kind of lighting (?) issues of dissimilar metals corrosion may impact their low voltage performance... specifically the connection to the electrical device itself -- LED, bulb, whatever. Those leads will like to be mated to copper conductors, most likely. Good environmental testing will prevent pricey re-work, of course.
My ending thought is: make it out of plastic, (thick and strong as necessary) and stick SS trim on it... Tie electric to separate trim pieces.
05-14-2010, 06:37 PM #7
Your laser guy doesn't want to do it.
Set up a series of guides to stabilize it, get two lasers as close to opposing as possible, and powered feed wheels to run it through. Any decent woodworker could figure this out.
And don't answer your laser guy's phone calls, he has let you down.
05-14-2010, 07:55 PM #8
05-14-2010, 09:02 PM #9
A decent laser cutting system is a quarter million dollars. And it is x-y mounted on a gantry over a table, not the kind of thing you can just pitch over on its side and slam another one up next to it to get both sides at once.
Even a good hi-def plasma system that will cut stainless with minimum dross is $80k or so.
With a good sized bandsaw, say, a Do-All 36-12, and a sturdy guide, you cut rip em right down the center pretty well.
You would go thru the bi metal bandsaw blades, but thats a cost of doing business.
05-15-2010, 03:57 AM #10
2 plasma torches, some shaped blocks of wood and a infeed - outfeed table would work ok, expect some consumable usage on a run of this size though!
Practicaly i would be feeding it through the doall here to do that job. If feeds good and a bit of lube is used, coupled with a slow pace and eqauly slow band speed, blade life might be semi surprising. For these qtys i would be looking for a roller feed setup too!
05-15-2010, 06:05 AM #11
My gut feeling let's me agree with the last two posters, it might be old fashioned, but if a good old band saw can do it, I would prefer that. I do not own a band saw of this type and quality, therefore it is good info that people here think this might work. And it would be a relatively simple process which probably can be done quite locally-other than the more modern and fancier methods which I definitely would have to have done 'away'.
05-15-2010, 06:40 AM #12
I'm guessing the hole drilling/countersinking operation is going on a VMC.
Are the holes to be drilled exactly 180DEG on the tubes faces?
Could you drill through both sides in one shot, chamfer, flip part and chamfer?
Plowing through both sides at once would be a significant time saver. I'm probably just echoing what you've already concluded..
For the splitting operation, my vote goes to setting up a fixture on a vertical band saw and splitting them in that manner. However old school, it seems like they fastest/ most cost friendly route. A carbide tipped blade with a kerf as wide as possible, and the widest blade that will fit the machine, just to help prevent it wandering.
Hope I was of some help, and good luck.
05-15-2010, 02:16 PM #13
I would advise against slitting a square tube unless it has been stress releived . Any time I have cut square tube along its axis the residual stress from the way it is formed has changed the shape of the cut piece dramaticaly.
05-15-2010, 04:56 PM #14
I agree with your concern, I was thinking the same.
Just that in this case the two halves are being bolted back together (one of the reason for these many holes) with just a 1 millimeter electrical insulation layer between the two pieces.
So I guess while I would not be surprised by any warping of the individual u-channels after sawing, they will hopefully be just fine once they are being bolted back together with 3/8" bolts every 1'.
Don't you think??
05-15-2010, 07:05 PM #15
In my experiance when a square tube is slit along the axis the resulting "c channel " does not have parrallel sides . the residual stress can cause the the top of the "c channel to spread open so that the top is wider then the bottom . I think this would cause problems for bolting back together
05-16-2010, 09:11 AM #16
What are the conditions that require 316 over 304? That's a major difference in cost, and there's very few places where 316 would be required to resist normal atmospheric corrosion.
IMO you don't need anyone with a plasma, laser, bandsaw, vmc, drill press, or anything of the like. You need to find a shop with a 1/4 x 10' shear, 150 ton press brake, and a gang punching setup made for use in the brake.
11 ga sheet would be the cheapest form of stainless as compared to other shapes. Blanks sheared from 4 x 10 or 5 x 10 sheets, formed into the channel shape on the brake, and gang punched as the final step. Depending on the hole size, it might be possible to do the punching in the flat prior to forming.
Anyone who's got the proper equipment to do this job should be able to do the shearing, forming, and punching very profitably for about $1/ft exclusive of material costs. With 5 holes per foot, its doubtful you could find anyone who'd be interested in drilling and deburring all the holes for a buck a foot. I've done enough of this type work to know I can shear and form 8 10ft channels in less time than I could split one 10ft length of tubing on a bandsaw, and do it without worries of the tube spreading or twisting as its sawed.