Re: Wrecked Aluminium from chopsaw
 

The pistons in those cylinders generate the force numbers he mentioned.

Is there not a piston in each cylinder?

Re: Wrecked Aluminium from chopsaw
 

I'm with you - cylinder is a shape created by translating a circle or other plane figure, pistons do work.

Re: Wrecked Aluminium from chopsaw
 

Get a cheap band saw

http://www.cpojettools.com/jet-41445...zSQpHi5_B_CJk8

Re: Wrecked Aluminium from chopsaw
 

The whole point of the chop saw is that you don't need to mill the block to length first to make a part with it. I can hit +- 0.005" length tolerance on a run of parts with my chop saw and be ready to do everything else to it. 10 seconds, cut, 10 seconds, cut, repeat until done.
Just set it up right so you force everyone to use it right.

Also I really dislike JET. It starts out fine and becomes a huge hassle to maintain.

Re: Wrecked Aluminium from chopsaw
 

Without your setup forcing everyone to do it right, how could someone do it right by themselves anyways? What are some examples of doing it wrong, and what would be the consequences?

Re: Wrecked Aluminium from chopsaw
 

Could you add some detail on how you get those tolerances? Is that with the chop saw setup you posted on the previous page? Are you using any DRO to get that tolerance?

Re: Wrecked Aluminium from chopsaw
 

If you are doing a run of parts and use a stop block, butting your stock up to it each time before cutting, you can get very repeatable performance, and by measuring a part and adjusting the stop block, dial it in.

If there is a way to get 5 thou on a first cut though, especially on lengths exceeding my cheaper 8" calipers, I'd be all ears :0

Re: Wrecked Aluminium from chopsaw
 

You need to make it mind numbingly easy to clamp your stock, we literally have to flip a switch to clamp our stock, the kids like how easy it is. But really, clamp it, Period. Holding it by hand is asking to have it catch a part. Also hold the blade down as long as it spins, Period. If you don't do those 2 things you will have it catch a part and do 2 or 3 things. 1 ruin your part, 2 ruin your blade, 3 send the part flying possibly into someone's face.

No, I mark the part and set up my work stop(shown in the pic) which is a 1/2-20 bolt. I take a slightly oversize cut and measure with calipers how long it actually made it. Then I use the fact that my 1/2-20 it 0.050" per revolution to fine tune the final size. This is one of the reasons I need that second clamping piston, to hold things on my work stop side of the saw. After that, cut and done, cut and done.

First "cut", no. First piece, yes. You should get a bigger caliper, will not regret. But I suppose you could edge find it in a mill to measure it then trim it to final and cut the rest of the pieces.

I may have a slight obsession with my collection of calipers.
35" Vernier $150 Auction
18" Dial $180 Amazon (if you are cleaver with measuring you can get parts accurate to around 36" with these)
12" Dial $85 Amazon
6" Digital $35 Amazon
1" Vernier Mic $150 for a 0-1,1-2, 2-3, 3-4, 4-5 Starrett set from Craigslist

Re: Wrecked Aluminium from chopsaw
 

Trip to the ER for an open fracture in your finger, missing a() finger(s), or other injury.

Material setup can vary from saw to saw. I setup a piece of angle wrong in a chop saw and received an open fracture in my left middle finger for my mistake. I used a setup recommended for a saw that was nearly the same, but not quite... Read the saw-specific manual for setup guidance and clamp everything down in some form.

Re: Wrecked Aluminium from chopsaw
 

We use Starret 24" and 36" rulers graduated in increments of 0.01" and a jeweler's loupe to cut long stock to size. The woodshop teacher/retired machinist can get it to within your +/-0.005", but I haven't found a student (myself included) that gets it that close repeatably. Usually I find myself doing a post-mill operation to get it the right size.
Do you have a picture of how you set up your work stop and such? That seems like it would be really useful to get that last bit of precision out.

On the topic at hand: I despise using the chop saw. We have one of the Dewalt ones somebody linked to early on in the thread, and "loud" doesn't begin to describe the hell-scream it emits when somebody turns it on. The ultra high rpms and plastic clamping system doesn't help its case either, although to be fair I've never had stock flip out on me. The only time I use it over the bandsaw is when I have to cut super long stock (because, as I mentioned above, I can't get it to within 0.005" on the saw alone). Having a massive floor bolted bandsaw helps.

Re: Wrecked Aluminium from chopsaw
 

I use a couple of the dewalt saws at work for cutting steel. I also used a similar one in High school (including on one occasion while on 1747). They work and when used for the right application can cut fast flat cuts. However, they heat the material a lot (since it's an abrasive saw) and they are loud (which isn't an issue at work since we all have earplugs in anyway).

Re: Wrecked Aluminium from chopsaw
 

Miter saws intended for carpentry are intended for cutting longer pieces of relatively soft, solid material.

This presents challenges when we use them to cut aluminum shapes.

If we are cutting a heavy block or bar of aluminum, the challenge is that the block and blade are heating up and the aluminum begins to weld to the blade teeth. This can be addressed with interrupted cuts and lots of coolant / lubricant on the blade. I typically just use a squirt of cutting oil on the side of the blade between cuts.

The length is the next problem. Most miter saws do not support the cut material very close to the blade. This is a problem with thin wall aluminum shapes and shorter pieces. The easy fix for this is to add support to the back of the fence such as a large aluminum angle plate on each side of the blade adjusted for minimum clearance or zero kerf. This will support the material close to the blade and reduce the grabbing tendency.

The next issue is chatter and rigidity of the material in the cut. If you have a piece of the shape that can flex into the blade during the cut, it will and the material will tear and perhaps carbide teeth will be lost. The aluminum has to be solidly supported. This is a special problem with very thin walls.

I recommend clamps be used to secure the material whenever possible. The generally supplied clamps are OK, except they are usually too far away from the blade. If your added back support is made longer than the original saw's back fence, then you can use a scrap piece of wood to help clamp and support shorter parts in the saw with a spacer block on the outside, similar to toe clamps used on a mill.

I find my blades last a lot longer with frequent cutting oil application. I have also used beeswax successfully. Just rub the block on the sides of the blade teeth before cutting. It is a little cleaner.

Re: Wrecked Aluminium from chopsaw
 

One of the most important things to consider for safety is using the right tool.

I, and the shop where my team works, recently got one of these: https://www.amazon.com/DEWALT-DW872-...metal+chop+saw

It runs at a considerably lower speed than wood chop saws, and holds the material where the saw is cutting down, not up. These two features make this saw inherently safer to use than a chop saw intended for wood. It provides a very nice cut in aluminum, steel, and even titanium.

Re: Wrecked Aluminium from chopsaw
 

Thanks for the tip. I wasn't aware of the Dewalt DW872 but after reading up on it some I just ordered one for our team. Seems like it will be an improvement over our existing miter saw setup. What blade would you specifically recommend? The saw says it comes with a "do-all" 70T but I suspect there are better blades for specific purposes like everything else. Do you have a recommendation that you have found works well for cutting aluminum?

Re: Wrecked Aluminium from chopsaw
 

I just did some shopping this week for a more appropriate aluminum cutting solution than we have used in recent years. I purchased this blade yesterday and installed it on one of our 7-1/4" (Craftsman) chop saws and put seven or eight "Aluminum & Plastic" labels on the saw. I also purchased a decent wood cutting blade for our 10" DeWalt chop saw, and put a similar number of "WOOD ONLY" labels on it. We cut very little steel (apart from what we can cut with a bolt cutter and finish with a wire brush), so we'll see how this gets us through a season.