Chassis punches

[Barry]

Hi,

I'm casting the net wide for a 13/16" chassis punch and a 1-1/4" chassis punch to make holes in my pots. I've other options – hire places, buy cheapies (my pots are thin), approach an engineering firm, hit up a friend who works in stainless fabrication.

But seeing as the sizes mandated by theelectrichomebrewery.com are very specific and really must be exact, and seeing as a few here have gone this route with electric gear, I figured someone might have splurged on the GreenLee bad boys and be willing to loan them out.

Anyone?

[Scott H]

I have  22mm one that i got from hand tool house for $64 which i have used for my wieldless bulkheads. I'm also on the hunt for a 1-1/4 in for the elements, most plumbers have a 35mm which is a few mil too big and I'm not keen enough to try it on one of my pots and have it be wrong and not seal. When it comes to getting my 1-1/4 in cutouts done I'll prob just ask a few stainless fabrication outlets and see what they can do.

[Barry]

Cheers Scott,

So 22mm worked for you? 13/16" is 20.6375mm so I'm not keen to risk it with the "o-ring on the outside only and precise washers" method advocated by theelectricbrewery.com

My dad has a set but 13/16 and 1-1/4 are the only two missing – drat!

 

[Barry]

Ooh yes please Guy, at least then I'll only be hit for one if I end up having to buy. It's only for 2 holes eh!
From what I can tell 32mm is close enough to 1-1/4 (31.75mm) so as to be close enough.
I got my elements off Amazon, indeed they are the American 1" ones., but the nuts are NPS (straight thread not tapered).

Where abouts are you based mate? I'm in Whangaparaoa but work in the CBD.

[Scott H]

I made my own compression fittings with 1/2 ID nippling tube nuts washers and custom made my seals from a silicon baking tray (Heh sounds real MacGyver-ery now) 22mm was spot on no leaks see att piccys.. Although I have only done 1 so far, getting a bit more coin together to get some 70L pots to do the rest.

[Druid]

I bought what I thought were decent chassis punches to do my cheap pots but they weren't up to it - lost their edges and bent the edges of the hole instead of cleanly cutting through.

In the end I bought cobalt hole saws from the local plumbing supply wholesalers and used them instead - successful but you need to go slowly and use oil. I think they were comparably priced or cheaper.

[Chris Banks]

From a toolmakers perspective the clearances between the punch and die on a chassis punch would be 10% (just for example it varies with many parameters) of the metal thickness it is cutting

In order to give the of the shelf chassis punches a reasonable cutting range say 1.0 - 2.0mm the clearances are probably set for the median cutting thickness of 1.5mm (0.15mm)

Some of the cheaper pots are down around 0.5 - 0.6mm despite being sold as thicker which would need a tighter clearance so using the bigger punch to die clearances allows the thinner metal to be drawn into the die without cutting nicely , completely or at all and taking the sharp edge of the punch if you are really unlucky.

You could probably force it to work if you doubled up the thickness by adding a piece of scrap sheetmetal into the mix and cut a hole in both at once.

I am hoping this will go under Druids comment but knowing this site it will go wherever it likes....

[Barry]

I noticed that a smidge Chris, the edge of the hole bent over towards the die. Easy to tidy up but definitely something to consider with the cheap pots – they're thin but also pretty hard and unforgiving (one of my holes even tore just a tiny bit).

[Scott H]

What size pots are you using Barry?

[Barry]

50L – these ones: from Trademe

[Peter Smith]

looks ok for $50...

[Scott H]

Using the big 5.5kw Elements or smaller?

[Barry]

Same brand and shape/type, but 4500W.