Hole cutting in RSJ

[Rusty]

Hi all,
A mate asked me about cutting some 4" square holes in RSJ's (which are about 12" high) and I mentioned power saw cutters but not sure if they would be man enough,what do you think Guys http://www.amazon.co.uk/Dewalt-DW304PK-240V-1050W-Reciprocating/dp/B0002AJNQ0/ref=cm_cr_pr_pb_t
The joists are 'in situ' about 10 ft of the ground.

 

[rtbcomp]

I've moved this to "Tools Materials and Techniques" - I guess there'll be plenty of all three involved in this one!

 

[wheresmejumper]

i doubt it.plasma maybe?

 

[gordon stephenson]

My first choice if available would be plasma cutter,Second choice would be to drill a hole in each corner (for neatness/stress relief etc) and use an 5" angle grinder with good cutting discs.

 

[Shox Dr]

To use a sabre saw you would need to chain drill it. Or as Gordon suggested, four corner holes open up with a grinder and then into the corners with a sabre saw. Pity you didn't ask last week Lidl had Sabre saws in for 30quid. I've been waiting on them come back in for over a yr, I remembered to set my phone alarm this yr

Plasma would of coarse be a doddle

 

[Rusty]

Thanks' Guys My idea would have been to drill hole(s) in the corners then use saw to cut through to holes,not sure if that type of saw would be man enough for the job though I guess the RSJ would be 1/2" thick steel ? Do also have an angle grinder.

 

[madkayaker]

Have you assessed what strength will be left I the beam after you cut big holes in it?

 

[brightspark]

as said drill the corner holes and use some 1.0 mm slitting disks in an angle grinder would be the quickest

 

[Hitch]

Have you assessed what strength will be left I the beam after you cut big holes in it?

Quite.



Gas, quick lick with a grinder, job done.

 

[Engineer1964]

Quite.



Gas, quick lick with a grinder, job done.

Thats the method i use on structual steel

 

[brightspark]

Thats the method i use on structual steel

same here but the op hasnt any cutting gear or he wouldnt have asked the alternative

 

[Rusty]

Thanks' Guys, plenty of tools for Car bodywork (no gas cutting gear tho)

 

[Welderpaul]

Yeah, without the usual weapons of choice, drill 4 holes and use a slitter. Anything else is just too much hard work!

 

[Rusty]

Just been reading about these 'slitter' disc's and they sound the biz
can you guys who use them tell me a bit more about them and have you cut 1/2 " steel with them ? any recommendation on make to buy ?

 

[brightspark]

Just been reading about these 'slitter' disc's and they sound the biz
can you guys who use them tell me a bit more about them and have you cut 1/2 " steel with them ? any recommendation on make to buy ?

they will cut half inch no bother just keep running over the cut back and forth and dont put much pressure on keep the surface speed up without grinder slowing down and it will cut more eficciently

 

[Welderpaul]

Very quick, buy a decent brand, go steady with the cut and don't force the blade.
I've cut 25mm plate with them before, suprising how quick they cut. You will never go back to the 3/4mm wide 'cutting' discs again
Very often weld flat bars on edge to the perimeter of the hole on both sides to frame it up before cutting the hole to replace the meat taken out.

 

[Rusty]

Can you recommend a make of disc or what price would a good quality disc be please.

 

[Welderpaul]

We use Reca Klingspor and 3M.
Think we pay under 50p a piece, but thats with orders of 400+.
Don't buy Silverline

 

[Rusty]

Thanks' welderpaul/brightspark, are these the 3m ones -
http://www.bndabrasives.co.uk/bonde...ting-disc-115mm-x-1mm-x-22-2mm/prod_1288.html

 

[Welderpaul]

Yeah, they are the ones.