Hacksaw blades for aluminium - Page 1
Forum section: electronics / general

author: akis
author_rank: Frequent Contributor
timestamp: July 07, 2014, 02:20:17 pm
content: I am cutting some aluminium heatsinks at home, I have cut one using an ancient mini hacksaw (6") and a rusty blade... Not really a clean cut. What is the best TPI blade to get? I am buying a normal size hacksaw this time 12". Thanks

author: Richard Crowley
author_rank: Super Contributor
timestamp: July 07, 2014, 02:23:40 pm
content: http://diyhousehelp.com/tools/hand-tools/choosing-the-correct-hacksaw-blade-tooth-count/

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: July 07, 2014, 02:28:39 pm
content: A fairly course blade will be ok .If you are filing down afterwards rub a bit of chalk on it`ll stop the file clogging up. I use a dremel with a cutting disk ,it goes through aluminium like butter .

author: akis
author_rank: Frequent Contributor
timestamp: July 07, 2014, 02:36:38 pm
content: I just did that. I used my Dremel at around 12K-15K revs, and the cutting disk, on the aluminium heatsink. First, there is aluminium filings/powder flying all over the place, the dremel rotates clockwise, so held with the right hand and away means a lot of debris flying off to the left and into your face. Secondly it did cut the heatsink but there is no accuracy, as you are holding the extension bit with one hand. That is why I gave up on the Dremel and went back to the hacksaw to finish the cut.

author: TerraHertz
author_rank: Super Contributor
timestamp: July 07, 2014, 03:17:16 pm
content: Just so you know, the best tool to cut aluminum is a woodworking drop saw, with a relatively fine pitch and still sharp blade. If the blade has never been warped, and you clamp the metal piece and use the saw's feed slides, moving the cut forward slowly, you can get a really clean cut face that looks like it was milled.I guess you don't have access to one of those?Of course, best done somewhere the millions of tiny metal shavings aren't a disaster, can be cleaned up easily.Lacking a dropsaw, use the coarsest new hacksaw blade that still puts at least 2 teeth across the cut. Squirting some kerosene into the cut, and also when you are filing, makes it go much better.

author: DmitryL
author_rank: Regular Contributor
timestamp: July 07, 2014, 09:32:40 pm
content: Quote from: TerraHertz on July 07, 2014, 03:17:16 pmBTW, I found that usual soap soacked to the state of a mild paste works perfect as a lubricant for dealing with aluminium (not for other metals). I use it for taping screw in aluminium alloys and cutting it with a fret saw.

author: MacAttak
author_rank: Unknown
timestamp: July 08, 2014, 03:23:37 am
content: Quote from: akis on July 07, 2014, 02:36:38 pmI never could understand why a Dremel does that. Are all of the engineers there left-handed??

author: robrenz
author_rank: Super Contributor
timestamp: July 08, 2014, 03:31:10 am
content: Quote from: MacAttak on July 08, 2014, 03:23:37 amHow about putting the part on top of the tool instead of under the tool. Then the debris will be thrown away from you.If they made a Dremel rotate the other way you would complain that all your drills, saws, burs, etc. don't work.

author: Richard Crowley
author_rank: Super Contributor
timestamp: July 08, 2014, 03:32:26 am
content: Quote from: MacAttak on July 08, 2014, 03:23:37 amProbably not. But since drills and burrs work clockwise, making a counter-clockwise rotary tool would make it pretty much useless for drilling or milling, etc.

author: pickle9000
author_rank: Super Contributor
timestamp: July 08, 2014, 03:34:24 am
content: I always use my band saw.

author: David_jones
author_rank: Newbie
timestamp: July 08, 2014, 05:20:49 am
content: It's good technique .Good work really helpful for me practically .

author: notsob
author_rank: Frequent Contributor
timestamp: July 08, 2014, 07:38:47 am
content: you can also use those 1mm ish thick metal cutting disks on your 80mm grinder and touch up later with a file

author: Psi
author_rank: Super Contributor
timestamp: July 08, 2014, 07:48:49 am
content: Im always cutting extruded aluminium cases on the dropsaw which has a general purpose fine cut wood blade.It's cut over 100 cases and doesn't show any sign of damage.Yeah, i know i should get a proper alu blade.Just saying, any blade seems to work ok for cutting alu because it's so soft.(However, be very careful grinding alu, because it's so soft it tends to clog up grinding disks/wheels and throw them out of balance. Wheels have been known to shatter when grinding alu with very dangerous results)

author: akis
author_rank: Frequent Contributor
timestamp: July 08, 2014, 08:24:49 am
content: Quote from: robrenz on July 08, 2014, 03:31:10 amThen I cannot see what I am cutting. It's like asking me to place a loaf of bread over the knife while cutting a slice off.

author: akis
author_rank: Frequent Contributor
timestamp: July 08, 2014, 08:27:43 am
content: Quote from: Psi on July 08, 2014, 07:48:49 amHere we call it chop saw I think. I have one, but I would need a special blade, the one on it now is only for wood with perpendicularly placed teeth. And even then, the heatsinks are too small to be secured properly into such a large tool. I fear on first contact the heatsink is going to fly off.

author: akis
author_rank: Frequent Contributor
timestamp: July 08, 2014, 08:31:25 am
content: I bought a 12" hacksaw and plenty of blades. I also bought a 6" junior hacksaw with better grip than my old "one use only".http://www.amazon.co.uk/gp/product/B0009VX3DQ/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1http://www.amazon.co.uk/gp/product/B0001GS13G/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1As long as the blade stays true and does not veer off sideways, which is what happened yesterday using my ancient junior hacksaw...

author: SeanB
author_rank: Super Contributor
timestamp: July 08, 2014, 05:29:57 pm
content: I often cut aluminium with either a mitre saw or a circular saw. Tungsten carbide blades and gentle feeding and no issues, except for a single chipped tooth from cutting some chipboard with a hidden nail in it. Need to clean the blade after use and oil it as well, but as I do that anyway it is no big issue. On thicker items I tend to first use some cutting wax on the teeth for the initial cut.

author: KJDS
author_rank: Super Contributor
timestamp: July 08, 2014, 05:41:04 pm
content: Use an axe, just swipe through it with one big swipe. If if won't go through in one swipe, use a bigger axe.

author: akis
author_rank: Frequent Contributor
timestamp: July 08, 2014, 05:58:41 pm
content: Interesting idea. But my accuracy with the 3-4 foot axe is terrible. I have been chopping wood for years now and it does not get any better.

author: SeanB
author_rank: Super Contributor
timestamp: July 08, 2014, 06:15:36 pm
content: I do not have an axe easily at hand, but the 14lb Widlariser is within easy reach. A few strokes of that and you tend to have at least 2 pieces.

author: DrJoe
author_rank: Contributor
timestamp: July 08, 2014, 07:18:33 pm
content: Quote from: pickle9000 on July 08, 2014, 03:34:24 amBandsaw is the way to go. Even a table top model will have far more uses than you can imagine. Great on plastic, aluminum, tubing, and even wood.

author: Monkeh
author_rank: Super Contributor
timestamp: July 08, 2014, 07:44:09 pm
content: Quote from: akis on July 08, 2014, 08:27:43 amIt won't go flying anywhere if you hold it (if it's big enough to do that safely!). A normal fine wood blade won't have a problem with alu.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: July 08, 2014, 11:16:36 pm
content: If cutting with a circular saw of some sort, make sure you wear ear defenders & safety glasses. It's very loud and angry aluminium bees fly everywhere. Also if you use a wood cutting blade, select one that has little or no rake to prevent the work getting pulled into the saw. The blades made for cutting aluminium have a bit of a negative rake so they don't suck in at all. Naturally it will need to be carbide tipped saw blade.It leaves a very nice finish and is extremely quick. But if it's a small job then a hack saw works great with less mess.

author: Psi
author_rank: Super Contributor
timestamp: July 09, 2014, 10:31:29 am
content: Quote from: Paul Moir on July 08, 2014, 11:16:36 pmhaha, yeah, it does kick out chunks of alu everwhere

author: krivx
author_rank: Frequent Contributor
timestamp: July 09, 2014, 10:36:35 am
content: If you use fine abrasive cutting (like a high-speed dremel) be careful with the dust. Apart from screwing with your lungs it can clog in the wheel if you cut enough of it. If you get enough of it in the air apparently you can cause dust explosions but that's probably not an issue for a hobbyist cutting small amounts.

author: TerraHertz
author_rank: Super Contributor
timestamp: July 09, 2014, 12:51:56 pm
content: Quote from: Psi on July 08, 2014, 07:48:49 amIf you look through the range of cutting and grinding disks at the hardware store, you should find that there are some specifically for cutting aluminium. They work very well, somehow the metal does not stick to the wheel, so there's no clogging. Cuts the metal like butter. For roughly cutting large bits of alu to shape, or hacking alu things apart, they are great.

author: TerraHertz
author_rank: Super Contributor
timestamp: July 09, 2014, 01:19:31 pm
content: Quote from: Monkeh on July 08, 2014, 07:44:09 pmBad advice there about the holding. NEVER hold small objects by hand close to the blade on a dropsaw. If the object twists it can jam on the blade, after which very loud and fast things happen. Even if it happens to not pull your fingers into the blade, or hit you in the face/eye, just the very fast rotation of an object in your fingers can cause injury. The first (and last, hopefully) time I made the mistake of hand-holding a small bit of wood in a dropsaw, it impacted against the tip of my finger, pulped the flesh down the tip of the bone, and bruised all the joints of that finger. High velocity accidents - it's like being shot.One thing to do to make cutting small objects feasible on a dropsaw, is to make a no-gap cutting base and backstop. For the base just put a sheet of old MDF or plywood across the saw stage, so there's no slot. Set the drop saw vertical stop so the blade just cuts into the MDF.Also get a bit of scrap trued-up wood, and put it right across the back of the stage against the back stops. Clamp the new backstop and base sheets in place on both sides. Make a cut - now you have a backstop with just a thin slot the same width as the blade. You can put stuff there and either hold it with a scrap wooden push-stick, or clamp in place with other scraps of wood and G clamps. It won't move.Apart from that, yes, fine toothed wood cutting blades work perfectly well on aluminium. Even with zero or very little set on the teeth.

author: Monkeh
author_rank: Super Contributor
timestamp: July 09, 2014, 01:23:15 pm
content: Quote from: TerraHertz on July 09, 2014, 01:19:31 pmI explicitly said if it's big enough to hold safely, did I not? Thank you for the lecture on tools I use almost daily, though..

author: akis
author_rank: Frequent Contributor
timestamp: July 09, 2014, 04:03:31 pm
content: Due to the way the drop saws work, wouldn't a band saw be better to achieve a perpendicular cut? What I mean is that with the circular and very large blade, you need a lot of gap depth and a lot of contact with the flat part of the blade when its teeth are cutting the last bits of the object, this is the same with table saws too. With the chop saw sometimes I had to turn the object over to be able to cut it through.But I think a band saw would cut squarely and there would be much less contact and need for clearance.I have gone on Amazon and the band saw ratings are not that good even for the Sealey. Would you know of a cheap and good make?

author: Monkeh
author_rank: Super Contributor
timestamp: July 09, 2014, 04:04:25 pm
content: Quote from: akis on July 09, 2014, 04:03:31 pmThis is called using too small a saw. They make those blades the size of tractor wheels, you know.

author: mzzj
author_rank: Super Contributor
timestamp: July 09, 2014, 06:40:39 pm
content: Quote from: KJDS on July 08, 2014, 05:41:04 pmSwedish axe vs. aluminium heat sink:https://dl.dropboxusercontent.com/u/93888484/WP_20140529_001.jpg

author: akis
author_rank: Frequent Contributor
timestamp: July 09, 2014, 06:51:50 pm
content: That is not an axe, that is a little hatchet. Did you really whack the heatsink with it?

author: Paul Moir
author_rank: Frequent Contributor
timestamp: July 09, 2014, 07:33:20 pm
content: Quote from: akis on July 09, 2014, 04:03:31 pmA bandsaw, whether it be vertical wood type or horizontal metal type, will leave a finish like a hacksaw or a little rougher if using a blade designed for cutting wood. (No real surprise there - it's basically the same thing). The circular saw leaves almost a milled finish.Does anyone really use friction saws anymore, especially for aluminium? Maybe real thin stuff?

author: KJDS
author_rank: Super Contributor
timestamp: July 09, 2014, 08:34:32 pm
content: Quote from: mzzj on July 09, 2014, 06:40:39 pmThat's brilliant

author: mzzj
author_rank: Super Contributor
timestamp: July 10, 2014, 08:39:29 am
content: Quote from: akis on July 09, 2014, 06:51:50 pmYes i used thathatchetto "cut" the heatsink in half. That type of heatsink is made of tightly pressed aluminum strips and it will split with gentle persuasion

author: G7PSK
author_rank: Super Contributor
timestamp: July 10, 2014, 12:59:53 pm
content: Cutting aluminium with a friction saw or cutting disc will cause the disc to pin (clog up) to stop this rub some candle wax onto the disc this also works when cutting with a hacksaw, for small quantity of cuts a good hacksaw with 14tpi blade all hard blade is best flexible blades wander all over the shop making it very hard to get a straight cut.