Problem that I would like a solution for

[Hood]

If you are going to do it with plasma partially bung one end and a hose in the other so you can fill with water but still have a flow, the cut will then have a nice golden edge to it, see pic below of the edge cut on my plasma with the water table.
As has been said though, it will spring and bend and not be a slotted box any more. That may or may not matter depending on the use.

 

[northwest]

AND..........

Now the real question that should be asked.........

Why does it need a slot in it and what for????

I have absolutely no idea, this is a job, it's what the customer wants and I am not going to argue, I am just going to get on and do it.

 

[Guzrik]

I have absolutely no idea, this is a job, it's what the customer wants and I am not going to argue, I am just going to get on and do it.

Trying to push the material into the saw (as you would do on a wood-cutting table saw) is problematic. If you conventional cut, the blade is trying to lift the material off the table. Because it is above the thing being cut, if you want the cutter to press the material onto the table, you necessarily have to climb cut.

Clamp blocks on the table so that the profile cannot go left, right or up.
Slow rpm's and flood wth coolant.
Like @Hood 's idea too.
Pig of a job, warping migth make it impossible.

 

[Morris]

I have absolutely no idea, this is a job, it's what the customer wants and I am not going to argue, I am just going to get on and do it.

The real worry is that the customers expectations and the real world end product may vary somewhat.

 

[daedalusminos]

I would imagine it will spring out of shape as soon as the slot is made - can you try a short section as a test. Must be £250+/length

 

[minimutly]

Clamp blocks on the table so that the profile cannot go left, right or up.
Slow rpm's and flood wth coolant.
Like @Hood 's idea too.
Pig of a job, warping migth make it impossible.

All this and you can't even clamp it because it will close the cut..
Thin disc would be my go to, but I'm no plasma expert.

 

[Arc Tourist]

If it were me, I would make up a guiding jig at least 12 inches long, that would fit over "both" sides of the box tubing with just enough clearance to let it slide smoothly. Then weld the guide to the base plate of a Wall Chasing Tool, put in the appropriate blades with spacer, and use it like a circular saw with a guide to run down the length of the tubing. Run the cut with several shallow depth passes to minimalize heat.

I'd draw and post a sketch, but my camera has failed, so I hope you can visualise the idea ?

 

[bletchmonster]

I like Hoods water idea for plasma.
Even short bits of box section seriously turn into a banana when slotting with plasma .
It's hellish laborious , but thin disc in a grinder would be my go to.

 

[badabec]

Sub it out to someone else.

 

[morssdn]

Stainless blade in a jigsaw. Would need two run and prob some sort of jig to keep straight. I cut 3mm stainless sheet with one easily enough, with a Metabo 230v saw. Prob go through a few blades.

 

[gaz1]

the amount of times ive seen material spring closer is why i wouldnt cut the box in 2

id have used

6m angle iron to form the lip and the box and strip tig or weld every ft

id drop down a few ways than sometimes use expensive curtain rail

these are just drawings to form a curtain slide box either using plate, box section or angle iron to form it

all boxes can be bolted

 

[chip]

We did miles of track back in the day. Ours all came in two halves lengthwise and even then there was warping an bad folds. probably not practical with you wanting so few, but we used long straight jigs.
We would drop all profiled plates into the jig ensuring their all in line, And then drop in the lengths.
There would be a number of profiled plates along the length, ends middle an so on. and wedges or blocks used to spread ensuring an even gap along the length then weld up.

 

[Hitch]

Sounds like one of them jobs where if they told you the intended purpose, you could make a good decision on how to go about the job..

Tube laser, could be easiest. Pretty simple. Leave the waste attached with micro joints every 300 or so stop it opening or closing during cutting. Trim out afterwards.
Downside is the inside will be full of dross...is that important...Some don't like doing FI material..

Cutting disc, might be a bit wobbly...be a bit of a grubby job PPE up and get it done.

Milling machines, will be very slow going, but would remain clean and be accurate.. sections could be left.

Hand plasma, bit of grinding up after, and the inside will be dirty...if its a hanging runner, dross on the opposite face may not be much of an issue, just scrape it off.

Whatever you choose, I'd leave bits joined till the end and do a final cut out to keep it straight as possible.
And expect to give it some treatment after. Do you have facility to roll it back straight? Or roll the sides closed?

How about finish... is it an architectural feature surrounding some oak veneered panels that need to look spot on, or a hanging track 15ft in the air for a curtain in a damp environment...

 

[northwest]

How about finish... is it an architectural feature surrounding some oak veneered panels that need to look spot on, or a hanging track 15ft in the air for a curtain in a damp environment...

I was hoping you would pitch in. it is more the latter than the former. A return conveyor track apparently and after giving this some careful consideration I think a jig/guide and a box of slitting disks is going to be the way forward, yes we can put it through the big rollers if it bends. I was rather leaning towards @Hood 's suggestion of filling it with water and having at it with the plasma but I am not confident with it whereas I have had years of practice with a slitting disk.

 

[Maker]

If it were me, I would make up a guiding jig at least 12 inches long, that would fit over "both" sides of the box tubing with just enough clearance to let it slide smoothly. Then weld the guide to the base plate of a Wall Chasing Tool, put in the appropriate blades with spacer, and use it like a circular saw with a guide to run down the length of the tubing. Run the cut with several shallow depth passes to minimalize heat.

I'd draw and post a sketch, but my camera has failed, so I hope you can visualise the idea ?

Wall chaser is a cool idea.

 

[voipio]

If the prepared section comes out warped and bent after cutting/machining, surely it could then be straightened, by the judicious application of force or heat to the right places, to straighten it again.

 

[minimutly]

I was hoping you would pitch in. it is more the latter than the former. A return conveyor track apparently and after giving this some careful consideration I think a jig/guide and a box of slitting disks is going to be the way forward, yes we can put it through the big rollers if it bends. I was rather leaning towards @Hood 's suggestion of filling it with water and having at it with the plasma but I am not confident with it whereas I have had years of practice with a slitting disk.

If it's ERW box I would cut the joined side..

 

[gaz1]

it would be less time and messing around just going out buying some stainless box section 6m long

a plate 6m long and angle iron 6m long

weld it all up as in the diagram above

 

[Mark 2]

I've done this before and it warps from the tensions inherent in the manufacturing process. Didn't seem to matter whether you slot the weld seam or the opposite side.

 

[Turbo]

Might be wise to do a test/demonstration piece in some mild steel box the same size and show it to the customer.