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Discussion Starter #1
Anyone have a 3" or 3 1/4" carbide grit hole saw I can borrow/buy? I need to drill a couple of holes in my acrylic sump. I have the other sizes but they don't seem to have the 3" ones at home depot or lowes.



Thanks,
David
 

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Monkey Man
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if it acrylic your drilling you don't need carbide grit, a standard hole saw will drill it! that is what I drilled my 3/8 thick acrylic with...
 

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Discussion Starter #3
I not sure if using a hole saw meant for cutting wood would not chip or crack the thin walls of my sump?

Thanks,
David
 

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depends on the type of saw, there are many different ones out there, try to find one with fine teeth, and a drill bit in the middle, should be ok, just go slow, light pressure.
 

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I've never used a carbide saw for acrylic (just standard wood saws), but I would expect that the carbide saw would be caked up with melted acrylic after you were done and would be almost impossible to clean.

I've made holes in acrylic ranging from 1/8" to 3/4" with everyday hole saws from Home Depot without any problem. Just go slow and let the saw do the work.
 

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Acrylic Drilling

For those less familiar with drilling acrylic, I thought I'd post some tips I've accrued through the years of machining acrylic. Drilling acrylic isn't the easiest of tasks, so if you're new to it, be sure to study up on technique, and practice on some scrap pieces (from local DIY center) before tearing into a pristine tank!

A drill press is best for these applications for clean lines and limited cracking and chipping possibility. You may not have one handy though, so a hand drill is acceptable, but a few more precautions should be taken. For best results use drill bits designed specifically for acrylics. Regular bits can be used, but the cutting edges should be modified to prevent the blade from grabbing and fracturing the plastic - this is generally accomplished by grinding flats into the leading edge of the bit, about 1/32" with a tip angle between 60 and 90 degrees. This will allow the bit to scrape out the hole being drilled. I'm not sure that a typical aquarist will have access to or experience on a grinding wheel, but you can PM me if this explanation isn't clear. I suggest, if possible, to pick up an acrylic bit. If your local DIY center doesn't have them, I can give you some sources for them. Also, I've found that taping the front and the back is a good way to prevent surface chipping (on the back surface) and scratching (on the front surface) from a walking bit. You may also want to clamp a piece of softer material on the back side while drilling to further prevent chipping. These are just some tips off the top of my head, but practice is the only true way to figure it out for yourself.

For the best possible finish along the inside of the hole, you will want to use a bit with slow-spiral, smooth, polished flutes which will clear the hole of all shavings without marring or burning the walls. If the drill is correctly sharpened and operated at proper speed, two continuous spiral chips or ribbons will emerge from the hole. You don't want chips coming out (bit speed too slow) or half molten acrylic!(bit speed too fast) Also, if you have thick walls (3x the bit diamater) cutting lubricant should be used.

All this is important because rough holes can lead to cracking a few months down the line, which is pretty much dependent on the location of the hole. and the size of your tank, i.e. the pressures the acrylic wall will see. Cracking can lead to some baaaad mojo!

Well, hope this overly technical post gives you some insight into the fun of DIY tank drilling. I've never personally drilled a tank (a general newcomer to the SW community), but have drilled plenty of pieces to know how to screw it up. You can do it yourself, but practice is key! I have some ideas on constructing a drill press from a hand drill, so let me know if you are interested in that as well.

Hope this helps!

John
 

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Discussion Starter #7
Found one on ebay for $9.50 from some guy in Hong Kong. Looks like he sells all sizes of diamond grit hole saws. The shipping is a killer though. Another $10.

I would like to see the info on where to get holes saws made specifically for acrylic. Do you have the info? Just want to see how much they are.

As far as melting with the grit hole saws you do have to be careful about the heat since the grit is just grinding a hole through instead of cutting. I haven't had any problems with caking or the acrylic sticking to the cutting tools but I have been drilling only thin material on sumps and small tanks. I would guess that on thicker material you would need to use a lubricant and/or clean out debri while you are cutting/grinding.

I would really be hesitant to use a wood cutting hole saw for a hole this large. Has anyone drilled a 2 or 3 inch hole in thin acrylic with a wood hole saw? Just wondering because from the posts listed here it sounds like it works fine for smaller diameter holes.

The good thing about getting the grit holes saws is that you can use them for your glass tanks also. But when doing the glass the lubricant is required.
 

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davidt said:
I would really be hesitant to use a wood cutting hole saw for a hole this large. Has anyone drilled a 2 or 3 inch hole in thin acrylic with a wood hole saw? Just wondering because from the posts listed here it sounds like it works fine for smaller diameter holes.
I've drilled up to 3" holes in 3/4" acrylic and ~2.5" holes in 1/8" acrylic. Clamp it to a piece a wood (or even better, sandwich it between wood) and you'll be fine.
 

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Monkey Man
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I agree, I have drilled 3/8" thick acrylic with a 2.5" standard hole saw with perfect results...
 

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davidt said:
I would like to see the info on where to get holes saws made specifically for acrylic. Do you have the info? Just want to see how much they are.
I found a nice DIY site, at http://www.reefkeeping.com/issues/2002-04/jg/index.php that looks to match with my advise, so I would take it to the bank.

The site suggests unibits for drilling thin acrylic, but I suppose a trial on a practice piece would prove this for sure.

Also found another site that details with pictures what I suggested about modifying a standard drill bit http://www.plasticsmag.com/features.asp?fIssue=Sep/Oct-01

As for the plastic drill bits, you can generally get them from any plastic supplier, but I found one online at http://www.jmkdisplays.homestead.com/bladesNbits.html, with prices. Also found some prices at SDPlatics at http://www.sdplastics.com/plexipointdrillbits.html, but they require a $75 minimum order. An acrylic set might be a good idea for a group buy, though.

Revision: As for hole saws, I don't believe any specialty ones could be made, just drill bits. You would only want to ensure that it has a high tooth density for smooth edges and no cracking, so a metal cutting hole saw would work.
 
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