On 06/27/2017 04:53 PM, Bob La Londe wrote:
"JBL" wrote in message news
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

***

While not ideal for it I have severed a lot of 1/2 aluminum flat bar
(and thicker) with a 10" table saw. With plenty of lubrication it does
ok actually. I wouldn't saw any old carbide blade would do, because I
had a couple cheap ones that ripped off all the teeth in one pass, but
most name brands do ok for atleast a few cuts. Now I wouldn't put this
on an elcheapo table saw, but my Ridgid contractor saw Is only middle of
the pack as saws go. I've used it for 13-14 years or so for all kinds
of projects. For a couple years it was my dedicated aluminum hacker.
Now it only gets used for wood since I bought a horizontal bandsaw for
the metal shop.

I don't know if I would venture to cut dovetails with it, but I suppose
it might be possible some care and proper feeding. (pun intended) The
problem is going to be keeping the blade lubricated Maybe if you could
figure out how to make multiple passes you could fill the slot with
cutting oil between.

I think a variable speed router and a router table Might be the next
totally wrong for it option to consider. I used router as spindles on
my early CNC machines. They didn't last long, but one would probably
last long enough for the job your describe. Be pretty dangerous too.

The right tool of course is a milling machine and a dovetail cutter.
Could probably still use a carbide router bit if you plan lubrication
and chip clearance.


Thanks. Well, for now, it's all on hold. I've run out of money for
this hobby stuff and will have to now wait until the next paycheck to go
any further. I actually did manage to properly cut one of the dovetails
on the first table saw before it burned out. It wasn't easy and I
probably should have tried lub as you and the other suggest, plus it
wasn't the right blade. This time, I'll start off with a better blade,
more careful and slower cutting, and some lub. That is, when I acquire
the spare funds. The idea was to make myself several dovetails first
and then use those as templates to make a few more maybe to sell to
others. I lack a drill press too, which is a major stumbling block
since holes need drilled into the dovetails. I do have one of those
small drill holders that accepts a drill and then can drill straight
holes. This can actually work before I start cutting any dovetails, but
once the much smaller dovetails are cut, there just isn't enough surface
area left for the device to line up correctly.