Making 15/16" x 1-1/16" holes?

[svejkist]

I like Marshall LED power switches and would like to use them on my own chassis. However, I haven't been able to find a 15/16" x 1-1/16" (0.9375" x 1.0625", 24mm x 27mmish) knockout punch to make the holes. Does anyone have a source for the correct punch, or suggestions for an alternative method? Thanks in advance.

[shooter]

alternative method?

I got paid well for "other methods"


3mm fine point "sharpie", mechanical ruler, center punch, drill with quality bit, dermal with cut-off wheels, set of jeweler files, couple hours of cue'd up music

[RoadShow]

I like Marshall LED power switches and would like to use them on my own chassis. However, I haven't been able to find a 15/16" x 1-1/16" (0.9375" x 1.0625", 24mm x 27mmish) knockout punch to make the holes. Does anyone have a source for the correct punch, or suggestions for an alternative method? Thanks in advance.

I've always laid out the square with a Sharpie, opened up as much as possible with a step drill, and file it open.  I check fitment along the way with the switch.

Same for the IEC connector.

Typically takes me 10-15 minutes.

[svejkist]

Yeah, this is what I have done. But when I have to do five of them, it doesn't sound fun. Oh well.

[Lectroid]

 
If you have a jig-saw, buy a metal-cutting blade for it.  Drill your corners with a large enough bit so the jig-saw blade fits easily through the hole.  Then cut out the square shape you've drawn with the jig-saw.  You may have to clean up the edges with a file but I think it would be way easier than doing it with a Dremel-like tool or a file.

[Willabe]

If you have a jig-saw, buy a metal-cutting blade for it.  Drill your corners with a large enough bit so the jig-saw blade fits easily through the hole.  Then cut out the square shape you've drawn with the jig-saw.  You may have to clean up the edges with a file but I think it would be way easier than doing it with a Dremel-like tool or a file.

And you've done it both ways or you just think it would be easier?

The jig saw will be too big, bulky, and be unstable cutting a metal chassis. And the blades teeth, even though very small on a metal cutting blade, will still want to grab the chassis, not good.

The dremel will be much easier to control while cutting. That's what I use. 

[ALBATROS1234]

The only problem with dremels is the bog down and take a while to cut through chassis steel. It takes a steady hand but a small angle grinder make quick work of it.

[Lectroid]

@Willabe,

If you have a jig-saw, buy a metal-cutting blade … …but I think it would be way easier than doing it with a Dremel-like tool or a file.

And you've done it both ways or you just think it would be easier?

The jig saw will be too big, bulky, and be unstable…The dremel will be much easier to control while cutting. That's what I use.

Yes I have done it both ways. I don’t have a Dremel but the jigsaw works well. I do have a black & decker Workmate table that holds the chassis very tightly.   
Other than that, I haven’t noticed any of effects you predicted.

The edges might feel rougher than if I’d done it with a Dremel, but they don’t show once the switch is in. It’s a useful technique.

[Willabe]

Yes I have done it both ways. I don’t have a Dremel but the jigsaw works well.

I don't believe you. 1st you say you don't own a Dremel, then you say you've done it both ways.

If you don't notice a difference between the size and handling of a jig saw compared to a Dremel and have never had jig saw metal blades teeth grab the stock your cutting, then you haven't used them very much.

Like any other tool there is a learning curve, you need to get use to using the tool with it's blades and cutting different material with them.

I could use a jig saw for this, but I'd choose a Dremel over a jig saw for this cut in a heart beat without question. The Dremel will do a much better, cleaner job and it will be easier.         

I have the top of the line B&D Workmate and it does work well, and lots of different types/sizes of clamps to use with it. But, one of the problems is it's hard to get an amp chassis' side, that's only connected on 1 side to the rest of the chassis, to hold still. It's a bent narrow flap that is hard to get a clamp on it and still have room to move the cutting tool your using.

[Lectroid]

Yes I have done it both ways. I don’t have a Dremel but the jigsaw works well.

I don't believe you. 1st you say you don't own a Dremel, then you say you've done it both ways.

Aren't you maybe a little harsh there, bro?  I'm sorry my sentence was contradictory, and confusing.  That's on me.  I was working Q&D at the time, and edited two different thoughts together.  Badly. 

But for you to say right off the bat, "I don't believe you," before maybe asking first me to re-phrase?  That feels...unfriendly.  I don't believe I've been disrespectful to you in any way.  Why push back like that?  I'm curious.

If you don't notice a difference between the size and handling of a jig saw compared to a Dremel and have never had jig saw metal blades teeth grab the stock your cutting, then you haven't used them very much.

Only 60 years or so, it's true.  Have you tried using finer-toothed blades?

Like any other tool there is a learning curve, you need to get use to using the tool with it's blades and cutting different material with them...I could use a jig saw for this, but I'd choose a Dremel over a jig saw for this cut in a heart beat without question. The Dremel will do a much better, cleaner job and it will be easier.

Sure, please use your Dremel; it sounds like the perfect tool.  I wish I had one.  My method is aimed more at people like me who don't own a Dremel.  As you point out,

I could use a jig saw for this

it's not the optimal tool, but it will work.

Despite Willabe's incredulity, I've used a jigsaw to successfully cut square/irregular shapes in sheet metal many times over the years.  It works for amp chassis and IEC inlets' shapes, too.  Willabe raises some genuine areas of concern about using jigsaws, and about adequate clamping and proper attention to tooth-binding.  These do require some expertise to mitigate, but I believe that anyone can get an acceptable result with a jigsaw, if they have the requisite knowledge of the tool and the ability to clamp the work firmly. 

Beyond that, peace to all here below, and I'm outta here. 

[Willabe]

Have you tried using finer-toothed blades?

Jig saw metal blades are fine tooth blades, just like reciprocating saws. That's a given.

But they still can/will grab the stock because the metal wont give like wood.

[rake]

https://www.tubesandmore.com/products/nibbler-cutter-square-holes

https://www.amplifiedparts.com/sites/default/files/styles/uc_product_list/public/uc_products/s-t806.png

[bmccowan]

I suspect the upcoming election has everybody on edge. Square holes, jigsaws, Dremels, nibblers, etc. Ever watch the Red Green show? Explosives are a viable option. https://redgreen.fandom.com/wiki/The_Friendly_Side_of_Dynamite
Have a nice day.

[Lectroid]

I suspect the upcoming election has everybody on edge.

I suspect you are right.

Explosives are a viable option. https://redgreen.fandom.com/wiki/The_Friendly_Side_of_Dynamite.   
Have a nice day.

It's a good day in Virginia.  I'm going out to walk in the Big Blue Room.

[bmccowan]

That link was screwy - this one works.
https://www.youtube.com/watch?v=F6FwSb7zd6M

[mresistor]

Greenlee can most likely make you a rectangular knockout but here is an example of the cost of one of these below.  To recover the cost of one would require that you make many chassis holes and pass the cost on to you customers.


https://megadepot.com/product/greenlee-60025g-rectangular-knockout-punch-unit-0-4-x-0-8

[mresistor]

here's a list of Greenlee rectangular knockout punches
Search - rectangular | Greenlee

[Lectroid]

$553 list price for a 0.4" x 0.8" rectangular punch?  That's a lot of holes to have to punch! 

[Dealbreaker]

I know half the fun of building the amp is building the chassis....But if you can find a mom and pop sheet metal shop, its amazing how much time it can save. 
I live in Southern Ca, and this is my go to.  Jason is great and can make just about anything.  And he is quite reasonable.  If you can't find anyone local, send him your drawing and see what he says.
https://www.whlsheetmetal.com/
I have no skin in this.  He's just a shop I discovered a few years back.  If this violates the advertising rules, I apologize and will delete if needed.
Cheers-