slotting hollow sections

[jimbo1962]

Hi all
Ive to make slots in 100x100x8mm stainless hollow section, 13 mm wide by about 35mm long.
now other than drilling 2 x 13 mm holes and either cutting out the bit inbetween with a cutting disc or with a plasma
are there any other smarter ways of doing it ? Ive about 68 to do.
C

 

[oilcooled :)]

Make up a jig out of 8 mm plate, for example my plasma has a 7mm offset between edge of tip to cut.so I’d be making a template slot 49mm long and 27mm wide, and I’d make it insuch a way with tabs looking down that it grips the sides of your box and self centres.

 

[hotponyshoes]

If you have a plasma just make an oversize cutting template that you can drop over the box.

Just clamp a edge to a test piece and make a cut then you can measure from the flat to the cut line to see how much bigger your template needs to be.

 

[8ob]

13mm milling cutter modified to fit in a variable speed router

Bob

 

[hotponyshoes]

13mm milling cutter modified to fit in a variable speed router

Bob

In 8mm thick steel??
You might need both hands to hold that

 

[oilcooled :)]

In 8mm thick steel??
You might need both hands to hold that

There’s a thick nozzle on the Oxford plasma the thicker the template the better you will do every man has a different machine

 

[cianh91]

Sub out to someone with a tube laser

 

[Agroshield]

If the overall length is 35mm, a 13mm hole either end of that leaves 9mm at its thinnest (22mm fattest) in the middle. You would need a small dia. abrasive disk to reach 8mm deep and completely sever the material.

How about making the slot 39mm long? Three touching holes (rotabroach, not twist drill) and then carbide burr in router as 8ob suggests to dress off the four unsavory bits.

 

[James1979]

Make up a jig out of 8 mm plate, for example my plasma has a 7mm offset between edge of tip to cut.so I’d be making a template slot 49mm long and 27mm wide, and I’d make it insuch a way with tabs looking down that it grips the sides of your box and self centres.

What he said.

 

[mike os]

Plasma or laser …. Cnc ideally

water jet ? Don’t know how the hollow section works out

 

[jimbo1962]

cheers guys I'll try the template approach.
Should I pilot drill a hole to let the plasma start cutting more easily?

 

[Brad93]

Hi all
Ive to make slots in 100x100x8mm stainless hollow section, 13 mm wide by about 35mm long.
now other than drilling 2 x 13 mm holes and either cutting out the bit inbetween with a cutting disc or with a plasma
are there any other smarter ways of doing it ? Ive about 68 to do.
C

Tube laser

 

[oilcooled :)]

cheers guys I'll try the template approach.
Should I pilot drill a hole to let the plasma start cutting more easily?

Depends on your plasma piercing capabilities, drilling a small hole is easier on plasma tips tho but that’s a lot of drilling if I could get away without it I wouldn’t bother

 

[tom2207]

depends how accurate the end result needs to be ,,, thats something else to keep in mind.

 

[James1979]

You can pierce with a hand torch by holding it at an angle and then as it blows the dross away gradually straighten it up. Like you would an oxy torch.

I’m not sure it’s recommended as such but I do it and its a lot easier on the tips.

 

[bletchmonster]

I would pre drill, piercing with the plasma tends to splash the template with dross and mess up the cut edge

 

[Brad93]

You can pierce with a hand torch by holding it at an angle and then as it blows the dross away gradually straighten it up. Like you would an oxy torch.

I’m not sure it’s recommended as such but I do it and its a lot easier on the tips.

More likely to cause side fluting or oval the tip if you tilt the torch.

 

[hotponyshoes]

Fit a old tip and pierce them all at once, clean up the metal then swap to a good tip and run round the template

 

[James1979]

More likely to cause side fluting or oval the tip if you tilt the torch.

Never knew that

 

[Brad93]

Never knew that

It's not gonna make a huge difference but particularly when initiating if the tip is tilted to the work, the arc will want to wander to one side, once cutting the plasma arc will be less likely to wander.