cutting 1/2" thick aluminum bars on a budget?

I am attempting to make a few "dovetails" which are brackets used to attach a telescope to a telescope mount. If purchased outright, for the
kind of dovetails I need, the expense is beyond my budget. I recently acquired some 1/2" aluminum sheet/ bar. The dovetail needs to be 1.75" wide at the base, with the sides cut at a 15 degree angle. Length can vary a bit, but usually about 12-14". My plan was to make at least 3 for the various telescopes I have.
I thought I'd be able to get away with an old circular table saw I had. Last week, I made some 1/4" thick dovetails of a slightly different design using my table saw fitted with a plywood blade. This went well, but when I tried to make these thicker 1/2" dovetails today, I ended up burning out my saw.
Ideas for a cheap way to make these dovetails would be welcome. I've been watching Craigslist for another circular to replace the burned out one, but I don't think it's the best tool for this job without a $30 plus blade made to cut metal and even then I'm not sure it will do it.
Thanks in advance for your help, John
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I have cut aluminum with circular saws, both hand held and table. The key is to use carbide tipped blades. I'm pretty sure that your plywood blade was not carbide.
It will not cut aluminum as fast as it cuts wood (duh?) - so don't force it. You can also make multiple passes, starting with the blade low and raising it each pass.
It is much harder on the blade's sharpness than wood is (another duh), so I keep a separate blade for aluminum.
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On 06/25/2017 12:02 AM, Bob Engelhardt wrote:

This is the blade I was using:
http://www.homedepot.com/p/Avanti-10-in-x-200-Teeth-OSB-Plywood-Saw-Blade-A10200X/202021698
I think you're right, not carbide.

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"Bob Engelhardt" wrote in message
BTW - for cutting something as thin as 1/2", you don't need a 10" blade - a 7-1/4" blade will do. $5.99 at HF:: https://www.harborfreight.com/7-14-in-24t-framing-circular-saw-blade-62733.html
********
Maybe they are better now, but I think the blades I ripped all the teeth off of described in my other post came from HF. They were 10" blades.
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On Sun, 25 Jun 2017 00:02:59 -0400, Bob Engelhardt

and wear a full leather suit and a full face mask. Those aluminum chips are HOT and SHARP and they fly EVERYWHERE. Also make sure to protect the motor so NO chips can get into it.(Here is where a belt drive saw with a totallt enclosed motor is highlt recommended!!!) Yes, experience talking!
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On Sun, 25 Jun 2017 13:48:12 -0400, snipped-for-privacy@snyder.on.ca wrote:

Yeah, I --much-- prefer hack and bandsaws for cutting aluminum for that very reason.
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On Sun, 25 Jun 2017 00:02:59 -0400, Bob Engelhardt

I have cut 3/4" aluminium with my wood cutting band saw, 1/2" 5T.blade which I use for general shop work. Bonus - you can tilt the table rather than the blade.
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On Saturday, June 24, 2017 at 8:13:25 PM UTC-7, JBL wrote:

You can get metal-cutting (carbide) blades, and can get 'em ground for a 60 degree bevel on the edge, so that the blade cuts one sidewall of a dovetail socket. It's easier, though, to get a bar and bevel its edges, for the male half of the dovetail, then another bar beveled at the edges can be ripped in two, and the halves mounted on a plate to form the dovetail female.
Don't write off your saw just yet, it could have something simple like metal shavings in the brushes. A cleaning and some lube can bring it back to functional.
If a track is what you need, there's suppliers that can deliver it by the millimeter, with lots of options. <http://www.igus.com/drylin
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The table saw I chose for cutting aluminum with a carbide blade and sheet steel with an abrasive disk is an old Craftsman that has the blade on a fixed arbor which extends out the side to a pulley. The table tilts instead of the blade. The saw is on a plywood table with the motor underneath, shielded from metal chips or abrasive particles and sparks. The motor mount is hinged so its weight tensions the belt which slips if the saw blade or abrasive disk binds. I jam a hockey puck under the motor mount to adjust the belt slip.
Since I have more tools than storage space the motor is part of a belt-disk sander that can be flipped up to use it, or down to use the saw. Either way gravity tensions the belt. It isn't the fastest cutting machine but it tolerates jamming well and gives me some ability to cut metal larger than my more precise machines can handle, such as 4'x8' sheets.
The hinge it flips around is a pipe across the center of the plywood. The saw is raised to clear the pipe and make blowing out sawdust easier when I switch from cutting wood to metal. -jsw
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wrote:

Mine got a fatal dose of "indigestion" when the hot sharp aluminum chips damaged the insulation on the armature and shorted it out. All the "magic smoke" came out at once - - -.

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Now is the perfect time to learn how to _really_ use a file. This is your cheapest option and the best way to learn a necessary skill. (Now watch you scoff at it.)

(Burned out your saw? Nasty comments about your IQ suppressed, but most people know when to quit.) HSS plywood blades won't hack it. Try carbide.

Drop by Harbor Freight and get some $5 carbide tipped blades. Oops, they no longer make the cheapies. (Kids are screwing it up, bigtime.) Too bad. 46231 and 00529 are some I still keep in stock. Depending on the alloy, these C3 tips can leave a rough cut, but some alloys cut cleanly. Avanti 10" x 60T blades are $15 at Home Depot. Cut the angle and file the bottom corner. Or regrind the teeth to 15. This is if you were overstating the burnout of the table saw motor. <sigh>
Freud carbide tipped dovetail bits for wood are 14-degrees and are $17 at Amazon with free Prime shipping, if you're a member. A router could make quick work of it for you, if you can make jigs.
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On 06/25/2017 12:45 AM, Larry Jaques wrote:

I was under the impression that the Craftsman I was using just might have some sort of thermal protection circuit. Unfortunately, turns out that it did not. It wasn't a huge loss though as I got it surplus.

Yes, I don't see those blades listed at HF. I assume you mean this one from HD: http://www.homedepot.com/p/Avanti-10-in-x-200-Teeth-OSB-Plywood-Saw-Blade-A10200X/202021698
The one I used during the burnout was this one: http://www.homedepot.com/p/Avanti-10-in-x-200-Teeth-OSB-Plywood-Saw-Blade-A10200X/202021698?MERCH=REC-_-rv_nav_plp_rr-_-NA-_-202021698-_-N
I guess $5 more might have saved the saw. Ok, guess I'll start over looking for another surplus saw and pick up the better blade and try again. Thanks!

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On Sunday, June 25, 2017 at 7:05:09 AM UTC-4, JBL wrote:

-A10200X/202021698

-A10200X/202021698?MERCH=REC-_-rv_nav_plp_rr-_-NA-_-202021698-_-N

Do not use a plywood blade. Use a blade with about 8 to 24 carbide teeth. And do not feed too fast. wear eye and ear protection. The plywood blad e has too many teeth and since they are not carbide tipped the teeth will g et hot and then dull. And being dull will make them get even hotter.
Dan
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On Sunday, June 25, 2017 at 8:32:26 AM UTC-4, snipped-for-privacy@krl.org wrote:

. And do not feed too fast. wear eye and ear protection. The plywood bl ade has too many teeth and since they are not carbide tipped the teeth will get hot and then dull. And being dull will make them get even hotter.

I forgot to add that you might tell where you are located. Someone here mi ght be close and willing to help you.
Dan
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Nope, you just completely ignored it. Same, same, so solly.

I see that you did not learn the lesson from that experience. You're on your own.

What part of "Oops, they no longer make the cheapies." did you miss?

No, I don't ever use "plywood" blades, preferring a dull box cutter to those. (that was a joke)

No, learning to stop trying when a blade isn't cutting is the lesson you fail to learn. If it's not working, stop and determine what is wrong. Check the sharpness of the blade, verify rotation, verify applicability, etc. Plywood blades don't work on metal. Got it?
You're either a troll or not a tool-using human. G'luck!
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On 6/25/2017 9:50 AM, Larry Jaques wrote: ...

Hey ... cut him a break. So, he's new and lacks tool savvy, but he's reading and replying to our posts, which is a good sign.
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wrote:

Hold off until he learns to put up with you.
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On Sun, 25 Jun 2017 11:03:42 -0400, "Jim Wilkins"

I was easy on him (helping) until I saw his 3rd post admitting more and more culpability and tool abuse. He should take your link and run with it.
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On 06/25/2017 09:50 AM, Larry Jaques wrote:

Completely ignored what? Using a file to achieve the necessary 15 degree angles on both sides of the aluminum. Even you expected I would "scoff at it" which I did. What was the point anyway?

What lesson? The saw was burned out yesterday, period. Nothing else has been done until I researched further, which was the primary reason for coming to this group.

Got it. GOT IT. Do YOU get it?

Now for that I stand corrected. The link I asked about above was not the link for the blade you were referring to for $15. Can our precious Larry forgive the oversight? Me thinks not and me doesn't give a rats you know what anyway.

If you weren't prepared for additional questions for what you perceived as obviously a newcomer, then you shouldn't have responded in the first place. Fortunately, I don't have time to sit here and argue with a has been and I am now adding you to my kill file so I will see no more responses. You ought to take the advice of other group members here and give people a break. You remind me of a serious narcissist that probably has some significant issues going on at home that warrant serious attention. What a pity that this is the only channel you have to vent your frustrations.... but it will no longer be at my expense. BYE!

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