punching a hole in square tube

[bigegg]

I have a need to make a LOT of through holes in some 1in square tube.
The holes will be 1/2", spaced every 4 inches, centred on the tube, and I have about 1000ft to make.

I want to do this "in house".
I have a drill press, and I have a fly press
I think that making a punch for the flypress is going to work better than drilling - especially since I can sharpen a press punch a lot faster and easier than a drill bit.

has anyone any experience of punching holes through tube?
I'm worried about deformation
I'll be doing full 24' lengths of tubing, so using a mandrel die is going to be difficult.
I'm thinking a piece of 3/4" bar, which will be a slip fit in the tube, with two 1/2" holes - one for the punch, and one for a locating pin through the previous hole.
I think that deformation of the hole is going to jam the mandrel/die inside the tube.

 

[Welderpaul]

You can't punch tube..you will flatten it before the punch goes through the steel.
I don't think the mandrel idea will work.

Look up tube laser on Parker Steels website...that's the boy

 

[Hitch]

Id drill them if you are desperate to do it in house.
Very limited knowledge on this, tube is a bit different to box, box normally tends to have a support bar inside to keep the face flat, tube sits in a former from memory, top section and bottom section hold it tight, then the punch comes through the top former thing.
Only suitable for light gauge material too.

 

[bigegg]

can't afford *that*
<looks on ebay for a cheap laser to fit my CNC router>

 

[bigegg]

If a made a support which fits around the outside of the tube, that would stop it flattening?

 

[bigegg]

am I using the wrong term?

mild steel square box section 25mm x 25mm tube like you'd make market stalls or gates with?

 

[Hitch]

If a made a support which fits around the outside of the tube, that would stop it flattening?

I think that works better on (round) tube, with box section (square) the face would squash in.

 

[Vdub lover]

You should be able to punch that easy, what the thickness of the box ? and what type of hole do you want square or round.

 

[bigegg]

You should be able to punch that easy, what the thickness of the box ? and what type of hole do you want square or round.

round holes in 2mm thick

 

[Vdub lover]

round holes in 2mm thick

Might be better off just drilling them then.

My mate who runs a gate company just had to build over 800ft of gates and railings after a lot of thought he just ordered the flat bar pre-punched and then drilled the box sections as needed, it'll take a lot of time tho.

 

[Engineer1964]

I don't think your gonna punch a hole in either box or tube thats only 2mm thick. Even if it was 6mm thick you will flatten it before it even conciders punching a hole. The Only way is Laser cut

I've love to see pictures of someone proving me wrong

 

[Paul.]

Tube punching, http://www.youtube.com/watch?v=r_aELzW4BZs
Actually quite common in manufacture of garden furniture, tent frames etc, thin wall erw is often punched in a press using a fixture to support the tube and the punch has a long tapered point like a large hypodermic needle, no die is used and there is distortion of the tube, have a look at a cheap garden chair to see the result, for accurate results though cnc punching is the answer

 

[Engineer1964]

if you look carefully at that video you will see the die inside the tube, Thats why there is a long bar, because at the end where it punches its attached to the Die, to stop the die moving.

Not everyone engineering company is going to have a machine like that unless your manufacturing tube or box with that requirement.

 

[Paul.]

Yes I know there's a die in the video, I was referring to thin wall tubing, its piercing rather than punching, very often the slug isn't even removed it just ends up hanging on by a sliver inside the tube, In a previous existence I used to make the tooling and jigs for a tube manufacturing company, I'll see if I still have any photos.
A bit of similar info here, http://www.daytonprogress.com/tech/dayton_tech-tubing.pdf,

 

[MattF]

Just drill the things. Simplest and cheapest method.