I need aluminum case cutting advice

[Jasonaaronfox]

It's been about 5 years since I did any cutting with a dremel. Do I need to keep the top of the case cool as I'm cutting into it? Would a powerful fan be enough, or do I need to keep pouring cold water on it and cutting slow?

What's the best method for cutting a hole for a 120mm fan? Should I print out a stensil and tape it to the case, then cut through the tape? Is there a better method? Should I drill pilot holes and cut between them, then buff with a stone?

I can't currently afford to buy a hole saw just to cut one hole, so this is the cheapest method I can think of. (cheapo harbor freight dremel for $8 and some diamond discs.)

I appreciate any advice someone with expreience has to offer. I'd prefer not to have to buy a new case just to AIO my graphics card.

Does anybody know if this circle cutter they sell would stand up to aluminum?

https://www.harborfreight.com/carbide-tip-adjustable-circle-cutter-68117.html

That looks promising.

 

[bigtallanddopey]

I don’t think that cutter you linked will be upto the job. I’ve never seen anything like that let alone used one. I could be wrong though if anyone else has used one and it works.

When cutting you don’t need to worry about cooling etc. It’s not necessary for one time jobs and aluminium is quite soft anyway. Cooling mostly prolongs tool life.

If you cannot get hold (borrow maybe?) of a hole saw big enough for the fan. Don’t think it needs a full 120mm size, can’t remember. The method I have used in the past is to template the area like you said and then use a jigsaw to follow the line. You can break it up into sections by using pilot holes. Then grind and sand down to the marked out line. The best method though would be to get hold of a hole saw big enough, that way it’s a perfect circle.

Using a dremel for curves can be tricky as the blade really only wants to go in straight lines. It’s doable but takes lots of patience. And again you will have to grind and sand the edges. Or you can buy one of those fan grills to hide any wonky lines.

 

[Alaric]

Unless you can turn the speed way down, a Dremel isn't the best tool for aluminum. Softer metals want slower cuts. The tool you linked to will work in a variable speed drill, too. That's what I would use. Cut slow, maybe have a spray bottle of water handy to keep the cut wet. While cooling may also prolong tool life, thin aluminum panels may warp from excessive localized heat-like ripping through it with a cutting tool. Slower on aluminum will also leave cleaner edges.

 

[Jasonaaronfox]

Unless you can turn the speed way down, a Dremel isn't the best tool for aluminum. Softer metals want slower cuts. The tool you linked to will work in a variable speed drill, too. That's what I would use. Cut slow, maybe have a spray bottle of water handy to keep the cut wet. While cooling may also prolong tool life, thin aluminum panels may warp from excessive localized heat-like ripping through it with a cutting tool. Slower on aluminum will also leave cleaner edges.

I'm leaning toward this idea. Worst case scenario I start the hole at 4.25" and have somone with a hole saw fix it at 4.5" if I mess up.

I've heard WD-40 makes a good cutting lubricant. Thoughts?

 

[Alaric]

WD-40 works. Pretty much any low viscosity fluid will work, the idea being to carry away heat for the most part. You shouldn't have to worry about the tool chattering in your case. Since 120 mm is 4.74" you can probably get away with cutting a 4.7" hole and just dress the cut edge with emery cloth to deburr.

 

[Robert17]

The aluminum transfers heat quite well and so the heat should dissipate through the mass efficiently, no coolant necessary. Drill a pilot hole using a Unibit, then saw to your template from there using an abrasive jigsaw blade (which are cheap and available at any good hardware or tool store). Just take your time which should even still only be about 5-10 minutes.

 

[don256us]

120 mm is about 4". Just use a 4" hole saw. It's aluminum so even a wood blade would probably work. The tool you show can work (I've done it) but it is not the right tool and you can really hurt yourself if it digs in and twists the drill and your wrist. My trick (dangerous) is to get the pilot into the material and let it spin up without the blades digging in. Then very slowly lower the drill to allow the two blades to gently "kiss" the material. Be quick to adjust for level. Keeping full control, continue to lower the drill until you slowly make it through. It you hit the material at an angle at speed, you'll hurt yourself and/or your material. It's not a good idea at all.

Remember, aluminum is really soft. A dremel tool will give it a $h!# look. Borrow a hole saw if you can't buy one. It doesn't have to be carbide or tungsten or whatever.

 

[godevskii]

It's aluminum so even a wood blade would probably work.

Wood blades have big tooth so it makes the cut on aluminium difficult and with rough edges.

 

[Witchdoctor]

Blue tape the entire surface,

Mark hole on tape,

Driill 3/8" hole in waste area close to edge but not on it

Jig saw with fine metal blade cut line

this is supper easy

Wear eye protection while drilling and using the saw

 

[maxfly]

hole saw it. dont waste your time trying to hand cut it. it will look like **** unless you cut way inside the lines and sand or grind the waste away. which will take forever. i did the 120s on my lian li pc65 with a hole saw. couldnt have been easier. with a hole saw you mark your center, drill the pilot hole and cut it out with a metal hole saw blade. if centered properly it will be simple to do and will look perfect. do a practice cut or cuts in a piece of wood so you know what to expect and go to town.

 

[Nebulous]

I used a hole saw to cut 120mm holes in an old Coolermaster Cosmos case. The side panel was a real pita cutting as the aluminum is at least 1/4" thick. The front was also thick as heck so cutting through it was a real challenge. I almost broke my wrists trying to hold my Makita hammerdrill cutting them. Word of caution: Don't be using any cheap drill/dremel to cut Aluminum. Use something with some torque, wear safety goggles and use the speed control. If the cutting wheel gets caught/jammed, it WILL break your wrist. Using a hole saw will leave alot of jagged edges so you'll have to sand those down real good. Wear heavy gloves or you'll shread your hands/fingers to bits!

 

[Robert17]

I guess it comes down to what power tools you may already own and what your budget may be. Four inch hole saws start at $15-$20; a Unibit (step bit) 3 pc set goes for around $15, abrasive jig saw blades go for $6-12 depending on if you get carbide or diamond grit. So if you've already got an electric drill, jigsaw, or access to them for a one-off project you can't go wrong with most of the methods above. Otherwise you could farm out the project to a local high school shop class if those still exist.

 

[Jasonaaronfox]

Everyone's advice is much appreciated, and has made me justifiably nervous! I contacted a local machine shop and they offered to cut it for $10. It is hard to beat that. I have a bad arm from my time in the service and trying to hold a drill steady didn't sound like a good idea for me. I will be using the advice given here to make sure he doesn't butcher my case!

Thank you all.

 

[Jasonaaronfox]

I had good results with the harbor freight tool. The machine shop used a drill press, and WD-40 did indeed make a good lubricant for cutting aluminum.

 

[Robert17]

Very nice indeed!