What kind of hole saw for a Lian Li?

DanG

I'm going to be cutting some blowholes in the side pannel of my PC71 for some more airflow. I want this to be perfect because I don't want to be spending another $95 on a replacement side pannel. I've seen metal hole saws and bi-metal hole saws. Will a bi-metal one work on an aluminum lian li?

muddocktor

I think that a bimetal hole saw blade is a hole saw that uses 2 different metals for the body and cutting structure, with the blade part being made of a very hard steel and the body being made with a softer, more ductile steel. I've used bimetal blades on my reciprocal saw and thats the way they're made. It gives the cuttings structure longer life with the blade staying flexible enough not to easily shatter.

csimon

I've seen some duct trim that looks really nice to cover the spot in case it doesn't look as perfect as you want it to ...will you be putting a fan there or just a blow hole (or suck)?
Here is a link to the blowholes at plycon ...http://www.plycon.com/cases/caseduct.htm ...may be cheaper elsewhere I didn't price shop. I think they are meant to be cut to whatever size you like along those ridges of the cylindrical throat ...looks like a good place to do it anyway if you need to.

DanG

I'm really not too concerned about the longevity of the holesaw, it's just got to last long enough to cut 2, possibly 3 holes.
csimon, it will be used with fans, but I'd prefer to have the fan on the inside of the case just for a cleaner look, so I'm not sure how that would work with the duct. I'm thinking some of the molding you can put on the edge of your car door so you don't chip paint off them if you open it into a wall would help clean it up.
So a regular bi metal one would do what I need?

muddocktor

I would think so. If you have a choice between coarse and fine teeth on the hole saw, go with as fine a tooth pattern you can get for cutting metal; it will make a cleaner cut.

MediaMan

Run out to your neighbourhood home depot/hardware superstore. They will have hole saws there. I think they are around 40 USD...I think.

Aluminum cuts really easy but here's the trick for perfect cuts.

1) The best choice is to use a drill press.
2) THINK carefully where you want to place your fan intake BEFORE you do anything. Are you going to go single 80, dual 80 or 92mm? or 120mm. Measure three times cut once.
3) Find the center of the hole and use a punch to mark the spot where the drill bit will bite.
4) Use machine oil or other oil to lubricate the saw teeth as it starts to cut.
5) Use slow, even pressure. Let the blade do the work.
6) If you have an air compressor handy blow the metal bits away as you cut.
7) Cut the fan box screw holes after you cut the main hole. Best to use a wire fan grill as your guide and use a punch to mark each of the four holes before drilling.
8) Make sure that the drill bit doesn't make too large a hole for the screws or screw head.
9) Again...use the drill press to drill the screw holes and slow even pressure.
10) You can use a fine tip felt marker to "dot" where the holes should be then punch. Alcohol will remove the felt marker. If you don't want to use felt maker then a pencil will do just fine.

I find that dual 80's one on top of the other work best. Place the upper fan first. It should not be directly over the heatsink. Move it down an inch or so. Remember that the center area of the fan produces less direct airflow than nearer to the center of the blades.

Position the next fan below that and REMEMBER to allow room between the two for the screw holes. Best to place and mark the wire grills before making ANY cut at all.

Measure 10 times if you have to before cutting once.


Hope this helps. I've cut about 20 cases this way.

DanG

That's now going to be the hard part how manu and where.
I will get a 4 or more channel rheobus for it to control the noise, so because of that I'm thinking a couple of 120's. One over the pci/agp cards, and one a bit further up that will blow right onto the heatsink.
Still undecided about weather to put one on top. I'd like to avoid that if possible just because the top of the case is rivited on.

MediaMan

I have ONE 120mm in the side of my PC71. That is more than enough. It is centered right over the video card.

a 120 in the top would be okay. COMPLETELY strip the case down with no parts at all...drill the hole and use the compressed air to really blow the case out so there's no little bits of metal hanging about.

bits o metal and PC parts = bad.

Straight_Man

Fine tooth saw, definitely. Can be high speed steel for an aluminum case, need not be carbide teeth. And, aluminum can be hit with a grinder tip in a dremel to smooth edges if you cut maybe 1\4 to 1\8" undersized holes and draw the diameter you want with a compass first.

One thing I have never had slip in aluminum is a Black And Decker titanium oxided Bullet point drill, and drilling a 1\16" or 3\32" hole works very well to keep a hole saw centered, as the 1/4" or so guide drill will bite in and follow your small guide hole. If no center punch (needle type), then get a tiny drill and drill a pilot hole, which will also work to give your comapss center a way to hold as you draw a circle. Measure to center 3X, right MediaMan, drill tiny pilot hole, draw your circle, use hole saw, and then grind carefully to circle outline.

Easiest way to avoid needing auto window molding around jaggies is to cut a bit smaller, grind to fit. Safety Glasses or Safety Goggles for cutting and grinding, please, eyes like metal bits even less than electronics. I shop vac the bits out, before building computer, if gonna mod that is first thing I do, except for side panels.

John.