Best way to make very large hole in cabinet

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MrAl
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Best way to make very large hole in cabinet

Post by MrAl » Sun Jan 03, 2010 6:47 am

Hi,


I want to mount a large fan in the side of the computer and that means i need to make a round
hole that will be very large. I havent decided to go with two 120mm fans or one 250mm and
one 120mm fan, but 250mm diameter is almost 10 inches in diameter so i would have to make
a round hole about 10 inches in diameter.

Any ideas on what would be a good way to cut this in somewhat thin steel?
I have a Dremmel with cutters but im not sure how clean that would come out.
I have sheet metal sheers but they are straight cut type unfortunately.
Might consider buying a tool if it's not too expensive and there is no other way.

Any ideas?

Thanks...
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JerryR
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Re: Best way to make very large hole in cabinet

Post by JerryR » Sun Jan 03, 2010 8:37 am

Hi.
Here are couple of ideas:
Draw the size of the hole in the desired location, drill a whole bunch of holes(whatever size you are comfortable with- 1/4" sounds about right for a 10" hole) just inside the hole marking, then with a small chisel break all the metal between the holes. You can smooth the edge with your dremel or with a file.
If this is a seperate panel that can be removed from the cabinet, and you have a drill press, there is a circle cutting tool that will work on steal/wood/plastics etc.
you can see it at : http://www.stanleytoolparts.com/bitsand ... tters.html
Personally I would not use it in a hand drill, only in a drill press at *slow* speed
I don't think that it will cut the 10" hole, but it will work for the 2-5" holes.
HD, Lowes, Ace , sears may have it in stock.
HTH
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Robert Reed
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Re: Best way to make very large hole in cabinet

Post by Robert Reed » Sun Jan 03, 2010 9:16 am

If you have unrestricted access to the panel and it is quite flat, it can be sandwiched between two pieces of 1/4" plywood with double sided tape. Then proceed with saber saw. I do a lot of thin sheet metal work with that and table saw and get clean cuts. This method gives backup to the sheet being cut and produces a nice crisp cut without any pulling. especially effect on aluminum.

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Re: Best way to make very large hole in cabinet

Post by Externet » Sun Jan 03, 2010 6:33 pm

Hi Al.
Do not know the name in english :sad:
It is an attachment to a drill bit and scrapes repeatedly the perimeter with its hard and sharp tip of its adjustable length arm when spins.

Seen it on hardware stores, looks like :

http://www.greatplanestrading.com/StP10-1/DSCN0363.jpg

http://www.barrule.com/workshop/images/ ... cutter.jpg

Or:
http://www.perfectwoodworking.com/my_fi ... ompass.jpg

Miguel
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Re: Best way to make very large hole in cabinet

Post by Robert Reed » Sun Jan 03, 2010 8:46 pm

First two are called circle cutters and for use on a stationary drill press. Largest cutter I have come across is 6" diameter and can be tricky to use with large diameter circles. I run mine at 200 rpm and it will still hang up occasionally. Last pix is a router and ferrous metals will raise hell with the bits, even carbide bits.

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MrAl
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Re: Best way to make very large hole in cabinet

Post by MrAl » Mon Jan 04, 2010 12:27 am

Hi again,


Thanks for all the interesting ideas.
One thing though, i dont have access to a drill press that is large enough to handle
a 10 inch hole cutter.


Robert:
You were saying that you used a sabre saw at one time on thin sheet metal, well did you
ever try a jig saw? I ask because i saw some blades that have 32 teeth per inch so
i was thinking maybe that would make a clean hole without needing the wood?
Maybe some masking tape on top first?


Another idea i am now considering is making the entire side panel over again. That is,
chucking the metal side panel and making it instead out of Plexiglass, and that is a
lot easier to cut than steel. I have actually cut this several times before and made
complex shapes with the Dremel and a special cutter i made for plastic like that.
Im not sure how strong this would be though. Might need some metal reinforcement.
Nice thing about clear plastic is it would act like a 'window' too that we now see in
some more modern cases. Still, have to think about this a while.

BTW, it would cost about 100 dollars for a new case with two 250mm fans already
installed plus another 25 dollars shipping. A 250mm fan costs about 20 dollars and
5 dollars for the 120mm fan plus about 7 dollars shipping.
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Re: Best way to make very large hole in cabinet

Post by Robert Reed » Mon Jan 04, 2010 7:30 am

I guess the term saber saw and jig saw are used interchangeably and yes I use a very fine cut metal sawing blade. But these saws have a habit of grabbing and pulling when the metal does not have FIRM support. This can result in a very unprofessional job. One thing no one has mentioned is a hand nibbling tool. These can be had for about $10, although for a circle of yours size it will require a lot of patience(30+ inches at <1/8" per nibble).But you can get a nice edge if followed by a little file work.

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MrAl
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Re: Best way to make very large hole in cabinet

Post by MrAl » Mon Jan 04, 2010 8:02 am

Hi Robert,


Yeah, hehe, a hand nibbler would work but i dont want to go through that much work :smile:
I guess i am stuck with a few different methods and that's it. I guess it doesnt have to look
super nice either, since it will be hiding once it is installed.
LEDs vs Bulbs, LEDs are winning.

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Re: Best way to make very large hole in cabinet

Post by CeaSaR » Mon Jan 04, 2010 8:31 am

If you wanted to bite the bullet, you could try one of these, but it doesn't say if it will cut thin sheet metal.
The write up only lists plywood, plasterboard, and acrylic up to 1" thick. It is used with a standard hand drill.
On the up side, replacement bits are available and you can keep just one set of them for cutting cases.

For clean edges, you would still need to cut the panel on a backer to prevent twisting the edges on the final cut.

CeaSaR
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Re: Best way to make very large hole in cabinet

Post by gerty » Mon Jan 04, 2010 8:52 am

I use a large knockout punch for fans. I believe one for 4" conduit is the one I used last time I had to put some fans in a PA cabinet.The punches are expensive, but a contractor friend of mine lets me use his if I show up with the cabinet in the back of my truck. :smile:

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Re: Best way to make very large hole in cabinet

Post by Robert Reed » Mon Jan 04, 2010 12:45 pm

MrAl
"I guess it doesn't have to look
super nice either, since it will be hiding once it is installed."

Well ala the Red-Green show, you can cover up any mess with Duct Tape. Of course it might be a worse mess when you are done :smile:

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Re: Best way to make very large hole in cabinet

Post by CeaSaR » Mon Jan 04, 2010 12:52 pm

Well, if it dosn't have to look "good", then how about a 12 guage 00 buckshot with no choke close range? :lol: :P

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Re: Best way to make very large hole in cabinet

Post by Janitor Tzap » Mon Jan 04, 2010 6:42 pm

MrAl,
What are you up too? :P

250mm fan in a computer case?
Are you trying for absolute zero degrees?

Or are you trying to cool the interior of the case,
to the point where you don't need cooling fans for the Video Card, Hard Drive, CPU, Chip Sets, and Power Supply?

This is a Mid-Tower case I'm assuming?

I've added fans to Mini & Mid-Tower cases.
You half to make sure the placement of the fan will insure the maximum amount of air through the case.
Use a ball bearing fan, not a cheap sleeve bearing fan.
It will last longer.
A fan with more blades will have a higher CFM then one with less blades{normally}.
RPMs will also be a factor in this as well.

Here's a gamer case that has the largest fan{200mm} mounted on the top of the case.
And 120mm fans mounted to the sides.
http://www.nanosys1.com/cs-an-ninehundredtwo.html


Signed: Janitor Tzap

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Re: Best way to make very large hole in cabinet

Post by Externet » Mon Jan 04, 2010 7:46 pm

- Abolish the deciBel ! -

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Re: Best way to make very large hole in cabinet

Post by MrAl » Wed Jan 06, 2010 2:03 am

Hi again,


Miguel:
Ha ha, that look cool, literally :smile:

Janitor:
That case looks nice, but im not sure if i want to put out the bucks for it.
Thanks for the info about the fans, i'll have to use that info when i make a choice eventually.
Right now i am divided between the 120mm fans and the 250mm fans. The 120mm would be
easier to install and are a lot cheaper too.
What am i up to? I figured if i use enough fans to cool the motherboard, CPU and hard drives
down to below absolute zero time would reverse and i would be able to recover some of the
files i lost over the years :smile: Just as long as none of the girlfriends come back as well :smile: :smile:

You were right about the fan card fan, i was thinking that maybe a 250mm fan would eliminate
the need for that seriously.
LEDs vs Bulbs, LEDs are winning.

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