Any Tips on Cutting Plates?

[CaptainRedBeard]

Hi all, I've got 2 pieces of annealed flattened copper, formally a bit of pipe. I tried cutting the circle for my shotgun condenser with my 4" grinder, wasn't working too well. So I tried to grind it down on the bench grinder, only to have it grab and bend the annealed plate. How have the rest of you gone about cutting them? Hole saw?

-CRB

[stilltryin]

hey mate.
i drew the circles and cut mine with a jigsaw, the blades were cheap at bunnings, then finish off with a file and a final rub with sandpaper and they were perfect. :handgestures-thumbupleft:

[CaptainRedBeard]

hey mate.
i drew the circles and cut mine with a jigsaw, the blades were cheap at bunnings, then finish off with a file and a final rub with sandpaper and they were perfect. :handgestures-thumbupleft:

That sounds like a good plan of attack. I'll have to head to bunnings tomorrow to pick up a jig saw. Thanks stilltryin

[P3T3rPan]

I cut mine with a pair of aviation snips

[CaptainRedBeard]

I cut mine with a pair of aviation snips

I haven't got any snips. I know I can pick up a jigsaw for $39 from Bunnings, I'll check the price on snips while I'm there, see what's better for $

[sp0rk]

I know with the talk around here lately of being careful with angle grinders that this is stupid, but this is how i cut mine yesterday
Put a suitably sized bolt in one of the handle mounting holes and clamped it as securely as possible in my vice
Put a thin stainless cutting disc in the angle grinder and switched her on, I worked my way around cutting chunks of the plate off until I was close to my final shape
Then changed the cutting disc out for a flap disc and used that like a disc sander and sat the plate on the guard and slowly and carefully worked it down to the perfect shape/size
Note for this I was wearing a face shield, ear plugs, welding gloves, steel cap boots, thick cotton work clothes and had a fire extinguisher right next to me with the pin already removed
I know this is quite dangerous, but it's the best method I had available to me at the time

[CaptainRedBeard]

I know with the talk around here lately of being careful with angle grinders that this is stupid, but this is how i cut mine yesterday
Put a suitably sized bolt in one of the handle mounting holes and clamped it as securely as possible in my vice
Put a thin stainless cutting disc in the angle grinder and switched her on, I worked my way around cutting chunks of the plate off until I was close to my final shape
Then changed the cutting disc out for a flap disc and used that like a disc sander and sat the plate on the guard and slowly and carefully worked it down to the perfect shape/size
Note for this I was wearing a face shield, ear plugs, welding gloves, steel cap boots, thick cotton work clothes and had a fire extinguisher right next to me with the pin already removed
I know this is quite dangerous, but it's the best method I had available to me at the time

I've found when I use angle grinders, for any projects/work etc, I struggle with accuracy due to the torque. I don't think I can successfully do it the way you did it sp0rk, it's just a little to daunting for me.

[P3T3rPan]

If you use any sort of power tool for cutting copper make sure that the copper is Very well clamped.
Preferably in a vice
The potential for the copper to grab and spit in your eye is very high as you found out.

[Yummyrum]

I've cut out many plates with snips ...its so safe ,easy and accurate .
Trick is to rough it out so you are about 1-2 mm off the line you need then around you go for the final cut, it will peel off like butter.

Then once you have drilled all your holes , re-anneal it and whack it flat between two boards

[P3T3rPan]

:text-+1:
What Yummy said

[P3T3rPan]

Another tip is to mark it out with a scribe or steel dividers, not a pencil or texta.
This allows you to use a bit of force to cut/scratch a line that doesn't rub off.
Snips will "feel and follow" this line/scratch, more easily giving you the accuracy that Yummy said :-B
A sharp nail or ss offcut will do the job if you don't have a real scribe or dividers
Two sharp nails and a piece of string I have used often as dividers

[northernbrewer]

I used a dremel with cut off disks with the flexi shaft. Variable speed, not much weight and easy to move around. In saying that I was cutting stainless not copper and i think snips might have had a lot of trouble doing it.

[sp0rk]

If you're going to use snips, pay for good ones, cheap crappy ones are just that. cheap and (very) crappy

[CaptainRedBeard]

I couldn't wait, you guys had made my mind up for me, and I scrambled down to bunnings and got some snips. Not sure whether they're the better or worse ones, they are multi-way cut, cost $25.
Gave it a crack and they cut smooth and easy! And safe might I add. Time to file it all back, mark out the holes, get Em drilled and solder me a shotgun!

[P3T3rPan]

way to go

[CaptainRedBeard]

Screwed up the Centre hole :angry-banghead:
Stepped up the drill size too quick and tore the plate. Time to start from scratch again :angry-banghead: :angry-banghead: :angry-banghead:

[sp0rk]

Drill before you cut the plates imho, esp if you're only doing 2" plates
Also I wouldn't bother annealing it before you give it a final bash flat, it's probably going to soften it too much
I just cut and bent mine flatish by hand, then beat it flat against a pine sleeper
Then marked and drilled it, cut the plates out and trimmed up
Then finally annealed and smashed flat between 2 wooden blocks and they're chilling out in a citric acid bath right now

[CaptainRedBeard]

Drill before you cut the plates imho, esp if you're only doing 2" plates
Also I wouldn't bother annealing it before you give it a final bash flat, it's probably going to soften it too much
I just cut and bent mine flatish by hand, then beat it flat against a pine sleeper
Then marked and drilled it, cut the plates out and trimmed up
Then finally annealed and smashed flat between 2 wooden blocks and they're chilling out in a citric acid bath right now

It won't be too difficult to cut the plates if they aren't annealed?

[sp0rk]

I guess you could anneal after drilling, I wouldn't do it before that though
The way I cut mine out, I didn't need to worry about it being too hard :teasing-neener:

[bt1]

Slight variation for my shed,

Same method for shotty end caps and plates for perf/cap plate trees for the columns.

piece of MDF pre cut to size with a hole saw to stabilise the saw, sandwich the copper with clamps between the pre cut and a scrap piece of MDF, load her up with lube and hole saw away.
Final sand and re check for fit and done :handgestures-thumbupleft:

bt1