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Recommendation for Unisaw cross-cut sled (for aluminum work)?

specfab

Titanium
Joined
May 28, 2005
Location
AZ
I have some fairly good-sized aluminum channels (12" x 5" leg U-channel) to cut with my Unisaw, and I am considering building a cross-cut sled setup that I can adjust for angle, which takes advantage of using both miter slots in the table. I want to bring these parts off the saw in a square and accurately sized condition, fairly repeatably, and I want to know if anyone has a recommendation for a commercially-available setup that I could buy if I can't make the time to build what I need.
 
Those UniSaws are a cult favorite, one of a number of goods useful for Craigslist scams.

There’s a small camper trailer that has a rabid following.

Oh, don’t forget the Kubota tractor being sold by the ex-wife for $2500...

If you are attempting a 5 inch depth, that’s a 16” round blade, say a 16” radial saw, or a Makita 16” beam saw.

2E21B722-E548-4ECE-AD38-91F97D253AE1.jpg model 5402

Or a bandsaw.
 
I have actually cut far more aluminum than I would like to remember with my Unisaw, and what that taught me is that the Unisaw is a pretty bad tool to use for that job. Especially channel, which is gonna be vibrating and wanting to catch and kickback if its sticking up 5" from the table. And my 10" Unisaw wont cut 5" up anyway.
I have cut bevels on 1" plate- multiple passes, with wax to lube the blade. It was the tool I had, but I wouldnt do it again.

anyway- I have had, and built a few crosscut sleds- and I used oak or similar hardwood for the bars that ride in the slots, and 3/4" ply for the sled. But I made fixed angle sleds.
If you are going to want a variable angle, I would say buy a sliding table for the saw. I used to have the Delta sliding table they sold for a while in the late 70s- it was pretty stout, and adjustable for angle. I still wouldnt cut 5" channel with it, but it was better than any shop built sled would be. Grizzly, Excalibur, and a few other companies make sliding table to fit a unisaw.

Me, I would use a horizontal bandsaw. No chance of kickback, completely safe, turns itself off when its done. High rpms on unclamped, hand fed aluminum is just a matter of time before something flies thru the air, and if it only hits you, thats probably the best case scenario. I have been hit by kickbacks from a unisaw, and knocked off my feet, 35 years ago, not even by aluminum. Certainly improved my safety behavior around one. But thats way better than being cut.

The other thing to consider might be a panel saw. Mine is not hefty enough, but some of the bigger ones with 3hp and up motors will do this job, and you are pushing the saw carriage, not the material- much safer. Something like this- Aluminum Composite Panel Saw
 
Thanks for all the input, even that based on assuming I'm an idiot;-).. Of course a Unisaw won't cut 5" deep. That's a major reason I'm trying to make a better setup to process these parts for a product development project; it does require 3 cuts to clear off the extra stock. Between posting earlier and now, I threw together a rudimentary double-runner arrangement with some flat-ground stock for the second table slot and about 3' of 40x80 aluminum extrusion, bolted to the flat-ground and clamped to the existing miter gage, for supporting the channel while it goes through the blade. The second slot support helps a great deal in guiding the material. I want to get as close as possible to parts that don't require secondary machining, since milling the ends is even more of a PITA. With a good circular saw cut, a little finish sander work gets them ready for chem-film and textured powder coat, no milling required if your dimensions are good. Bandsaw finish would require significantly more work.

The circular saw concept for processing aluminum is pretty efficient, IMO, if one is set up well enough. I've been using a tablesaw for quite a while (40+ yrs, I'm shocked to say), and aluminum has never scared me at all. It's very stable, but it does get warm... What scares me is ripping long narrow pieces of red oak or crap 2x4's full of knots, or trying to split 5/8" nylon rectangles about 1.5" x 3" at an angle, with a 40 tooth 12" blade on a contractor's saw, handholding the parts. Last time I did that was 1978, and I still get cold chills... Or trying to trim a blade-thickness off the edge of a 1/4" polycarbonate panel. Yikes.

The sliding table would be my preference also, but I don't have that, and probably don't have room to use one even if I got one. I'll take a look at what's out there, though. I used a Northfield 14" saw w/sliding table for a few tasks back in the late 70's, and that was a beautiful machine. This extrusion could likely be done on a good-sized radial arm saw as well, but rigidity would be key, and those require gobs of unavailable room as well. Bottom line is I need to work within my currently available equipment set.
 
I know you just said you don't have much room, so this is probably a no go, but look into a counter top saw. It would be similar to a panel saw but much smaller as it is only made for the depth of a countertop. The extrusion would be stationary and the saw would move over it. I think they could be capable of the 5" DOC. If you could find one cheap enough it might be worth making room for it. Same with a 16" or bigger blade RAS. I have a Wilson brand that is extremely beefy, more so than the original dewalts and I would be OK with cutting aluminum on it.

Another option would be to replace your unisaw with a bigger saw, preferably a slider too.
 
This extrusion could likely be done on a good-sized radial arm saw as well, but rigidity would be key, and those require gobs of unavailable room as well. Bottom line is I need to work within my currently available equipment set.

Ouch...
As someone who has processed a tad over #200K of 4.5 x 7 U-channels 3 years ago using a 24" table saw with a 14" custom blade, my suggestion
would be to find a way to overcome your space limitation.
If you can, then a table saw can be the cat's meow on the very cheap.

For rigidity, you can install a stabilizer bar on the front of the arm, but that will limit you to 90deg cuts ( or wherever you install the bar )
You also want to stiffen up the slide so it does not "bounce". I've used UHMW shoes pressed against the round guides and it worked pretty well.
The blade likes to "climb" into the material, so instead of pulling, push the blade into it so the saw is cutting upwards.
For lubrication WD40 is barely OK and very soon you will find it quite miserable to use and breathe in. There are specific MQL lubrications
out there for AL that require very little amounts to be squirted on the blade or the material. You can also use something like Evap-lube
or other vanishing lubrications.
The most important part however is the blade itself. Pretty sure you know this, but saying it anyway: Do not go to Home Depot or similar places
to look for a suitable blade! Get one that is specific to cutting Aluminum! There are many places that have off the shelf, or can make one in a jiffy.
My 14" blade was made complete in 5 days ( though they've had the blanks ) and it was flawless for thousands of cuts!
If you need one, Specialty Saws in Simsbury CT is one source.
 
Make your sled big and long. I used Baltic Birch and a piece of 3/8 x 3/4 CRS for the runners and set them in a 1/16 routed groove. VERY IMPORTANT!! Also attach a 1/16 x 1 CRS strip to the bottom of your sled to keep it from tipping off the table when pulled back too far. And you will at some point do that. For sure it will take some grinding and hand work to get it sliding perfectly, but well worth it. When mine started to fall I caught it with my knee and it fell back onto the blade. Lucky for me no metal was hit and the blade shot through the sled and sent in back onto the floor. It was too heavy to get a high speed launch but it was ruined after that.
 
I have always used 3/4x3/8" ground flat stock for the runner and this works very well. Drill and tap it in a few places and use flat head allen screws through the flat base to screw into.
 
I work alone a lot, and over the years dealing with large stock has led to some really bad ideas and the worst ones invariably involved the table saw. A nearly catastrophic disaster trying to cut dozens of 1’ sections from 12’ OAL, 4.5” OD 6061 round was the last time I did anything like that.

My solution now is to secure the stock so it’s stationary and roll the whole bandsaw into it. I anchor some 2”x4”’s to the floor to guide it and the setup has proved effective for many years now. It doesn’t have to move far, just the thickness of the stock, so it’s not a huge difficulty even with a 24” bandsaw. Angles are cut by jacking up one end of the stock.

One day I’m going to put down some short round rails and automate it. One day.
 








 
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