Wrecked Aluminium from chopsaw
 

Sorry for the mess up in the NASA thread. Button pushing fail.

Yeah, sorry about that. No one was hurt when the blade failed, but there were quite a few interesting chunks of metal that came out of it. ::ouch::

Re: Wrecked Aluminium from chopsaw
 

That has always scared me about cutting aluminum with a chop saw.

Re: Wrecked Aluminium from chopsaw
 

Looks like the blade had a few more teeth that where pretty close to going also. I would buy a cold saw or a nice horizontal band saw. The cold saw in or shop probably gets more use than any other machine there. Best money we ever spent and its a whole lot safer too.

Re: Wrecked Aluminium from chopsaw
 

How long is that piece that was being cut and which way was it being cut? Was it cutting the full width of the tube?

I don't think that the blade failed causing the aluminum to bend and bind, I think that piece is just too small to cut with adequate clamping force. The margin of safety on a miter saw is 4", I don't see how anyone's hands could have been clear of that margin. When the aluminum moved or twisted it snagged the tooth and when the material hit the fence the tooth snapped off. I have lost a tooth on a blade before and didn't have a catastrophic failure like that. I'd be curious as to the full details of what happened and exactly how the scenario unfolded.

Glad everyone is okay, stay safe out there!

Re: Wrecked Aluminium from chopsaw
 

Look at the Evolution saws.
They run at lower RPM.
They are cheaper than a new cold saw.
The Evolution blades have teeth both directions.

I had a piece do something similar to this after breaking a clamp.
The cost of the saw was nothing compared to the risk of harm.

Re: Wrecked Aluminium from chopsaw
 

I've always been slightly apprehensive about cutting aluminum on chop saws for the very reason pictured in this thread.

Horizontal chop saws are my first go to machine for cutting raw extrusion/rods, but after Build Blitz I'd also recommend this setup for those with space limitations: portable band saw (such as Dewalt DWM120) + aftermarket stand.

Re: Wrecked Aluminium from chopsaw
 

Obtained this guy before build blitz, and cannot recommend the setup enough.
Replacement blades are available from Home Depot etc, it's setup for much tougher cutting than your typical small bandsaw (wood/foam, etc).
It can easily handle steel/aluminum.
I would recommend the footpedal to control it.

-Aren

Re: Wrecked Aluminium from chopsaw
 

I love horizontal bandsaws, the only problem with them though is because aluminum is so soft and ductile, the blade may want to cut at a bit on a vertical angle, which can be easily corrected with milling.

Re: Wrecked Aluminium from chopsaw
 

Scary! I hate to think of where that tooth could have gone.

We have a wonderful horizontal bandsaw that my nice brother gave me, then I donated to our build space. It is so much safer than a circular saw - no possibility of making shrapnel.

Re: Wrecked Aluminium from chopsaw
 

This is by far the best purchase we have ever made in power tools. The Dewault DW872 metal cutting saw.

http://www.dewalt.com/tools/metalwor...aws-dw872.aspx



It can make cuts with no or minimal milling of cut ends.

It does have it's downsides though.

Loud (hearing protection loud), expensive blades (haven't replaced our's yet.), and bad clamp design (hard to get square).

Re: Wrecked Aluminium from chopsaw
 

Use the right tool for the right job. A chop saw may cut aluminum, a knife can also be used to eat ice cream. Just because a tool will do the job doesn't mean it is the correct one to use.

A reciprocating saw can be purchased for $30 at most any hardware stores. Combine it with a fine tooth blade and a vice and it will cut all the aluminum and steel you want-- safely.

Re: Wrecked Aluminium from chopsaw
 

There are chop saws designed to cut wood, and chop saws designed to cut metal, sometimes called multi-cutter saws. Much of the difference is where the cutting guide is located with respect to the blade. Saws designed for wood allow the center of the blade to cut beyond the guide, allowing the blade to 'pick up' on the material being cut. Not a huge deal in wood and non-metals where cutting forces are relatively low, but in metal it can be quite dangerous. Saws designed for wood and other non-metals will generally have 1-2 clamps pointed down, saws designed to cut metals will generally have 1-2 clamps oriented horizontally.

Very similar saws can act quite differently. Know the difference!

Re: Wrecked Aluminium from chopsaw
 

A reciprocating saw is not going to cut straight at all, and is far more dangerous than a proper chop saw for metal.

We run a metal chop saw with a blade meant for aluminum and kids have made at least 1000 cuts this year quickly and safely.

Re: Wrecked Aluminium from chopsaw
 

We use the MK Morse Metal Devil 14" cutoff

http://www.mkmorse.com/products/index.aspx?product=74

Best tool donation we've ever gotten

Re: Wrecked Aluminium from chopsaw
 

Although we have not cut anywhere near that number of parts on a chop saw, we do use them. We also have a LARGE horizontal band saw.
Both will do the job well IF they are used and set up properly.

Below is my ASSUMPTION based on the picture alone. I do not have enough factual information to give anything more than an assumption here.

My guess from looking at the picture is that the cut was from the top with a 45 degree vertical rotation to the blade. The part being cut was standing on it's narrow edge and not clamped securely. This set up is NOT ideal for a chop saw.

Lay the part with the larger side down. Use the horizontal rotation of the saw to set the angle. CLAMP THE PART SECURELY. Sorry for the all caps, but the importance of securing the part can not be understated.

It just struck me, the saw may not have been a Miter Saw! If not, it was the wrong tool for the job.

Re: Wrecked Aluminium from chopsaw
 

Same story here. Training and proper clamping is critical. The clamp that comes with the saw doesn't cut it. As long as you don't go too fast, you'll be fine.

Re: Wrecked Aluminium from chopsaw
 

Since this was the first post I'd seen on here about this, perhaps the OP could detail:

1) Material being cut (yes, aluminum- but what grade)
2) Orientation of the material
3) Dimensions of the material
4) Size of the cut (and the cutoff piece)
5) Was the material clamped?

Thanks. Would help me appreciate the level of risk here.

Re: Wrecked Aluminium from chopsaw
 

Hmm, it sure seems to have worked out well for the OP...

I reiterate- just because a tool will do the job doesn't make it the right tool!

A chop saw is NOT the right tool. Chop saws designed for structural tube are called cold saws and typically cost $1000+, have an automatic feed, and run at low RPM to prevent accidents such as the OP's photo. The capabilities of a consumer grade chop saw and aluminum end at things like window screen frames. THIS is a chop saw for structural tube ie: cold saw:



I contest anyone that states a reciprocating saw is more dangerous than a chop saw. How many people do you know have lost fingers to chop saws vs reciprocating saws??

A reciprocating saw will be challenged to make a perfectly straight cut but what are you doing that requires a perfect cut? Welding? Fill it. Anything that requires more precision than a saw cut should be rough cut and then machined.

Acceptable saws to cut structural aluminum:
-Reciprocating saw with bimetal blade
-Bandsaw (vertical) with appropriate blade and blade speed for metal
-Bandsaw (horizontal)
-Cold saw
-Hacksaw

Re: Wrecked Aluminium from chopsaw
 

This is not true. Check out the specs on a non-ferrous chop saw. You're looking at ~3,000 RPM.

A previous poster already linked to the DeWalt multicutter, which is specifically designed for cutting solid and tube. Adam is using a similar model. I know for a fact that some professional machine shops use these saws in lieu of a band saw, for cleaner, faster cuts.

Re: Wrecked Aluminium from chopsaw
 

We use a chop saw designed for cutting Metal that has a purpose built blade for aluminum on it. How is this not the right tool?

Yes, a cold saw would be nicer, but it's still on our wish list.

The OP likely was doing something improper and/or using the wrong kind of saw/blade.

We get square cuts off our saw, it's a huge time savings not having to mill ends. I'm in the business of maximizing my students time doing cool stuff (fun machining) and minimizing the lame stuff (hey lets face 200 tubes this season because our saw can't cut straight!). Suggesting we weld nonsquare tubes and just fill the edge is really a poor approach to the manufacturing process.

All the students and mentors cleared to use our saw have been trained, and they use it safely and without issue. Fingers shouldn't be involved in the process at all. Material should be clamped.

For ~$500 we got a saw that was able to cut up to 4" solid with square edges, you'd be looking at likely $5k+ for a cold saw with such capability (which is our next move, we really want one). A horizontal band saw that can compete in speed and squareness isn't really an option either.

Many of out industry professional sponsors running small to large shops run similar saws for certain cuts as opposed to their band saws for the same reason we do.

A reciprocating saw will do the job, but that doesn't make it the right tool ;)

Re: Wrecked Aluminium from chopsaw
 

lol alright then, have fun guys.

For those interested in doing things the right way, two options for properly cutting structural tube for less than $400:

USA: http://www.harborfreight.com/garage-...saw-93762.html

Canada: http://www.princessauto.com/pal/en/B...-Saw/8354789.p

For less than $50:

USA: http://www.harborfreight.com/6-amp-r...ngsaw-11142012

Canada: http://www.princessauto.com/pal/Reci...-Saw/8507626.p

Re: Wrecked Aluminium from chopsaw
 

I'd love to hear why you think a chop saw DESIGNED for cutting metal is not the right way? That's your opinion and not a fact.

If you use one you will change your mind.

We spend less time cutting and machining using our chop saw designed for metal.

For reference on a chop saw designed for metal here's a link:

http://www.homedepot.com/p/DEWALT-15...W872/203164101

Re: Wrecked Aluminium from chopsaw
 

The DeWalt multi-cutter is a fantastic saw.

In college I used a DeWalt multi-cutter to cut thick-walled alloy steel tubing, thin-walled titanium tubing, galvanized steel angle, all manor of aluminum extrusions, and practically everything in between. It runs at 1,300rpm and has a heck of a good clamp for securing work pieces. Never had a single incident with it.

It's such a good saw that the lab I was running was able to buy it with safety equipment funding, and it's barely over $400.

A saw like this is the 'right tool' no matter how you cut it. *rimshot*

Re: Wrecked Aluminium from chopsaw
 

We have a Grizzly horizontal bandsaw, a Dewalt 12" miter saw, and a Rage Evolution saw. The Dewalt is by far the go-to saw for precise cuts in box tubing. With a 72 tooth carbide tipped blade and a careful operator, it makes very nice, very precise cuts, with no real danger involved. You just have to go slow and not cut small pieces. I've even cut small pieces at odd angles with care and caution, and I've even cut 2" solid bar stock on it.

For bar stock, the horizontal bandsaw is our go-to machine. We run a Starret bi-metal blade, and put on a flood coolant system. These two improvements have made a night and day difference. Also, we put on a new 1/2 HP NEMA 56 frame motor. The original caught fire (actual flames) when we stalled the blade in some stock.

The Rage saw is great for steel box tubing, and I'll use it to cut aluminum flat bar now and then. But, it doesn't dry cut without clogging, and the vise is junky and hard to get square. It's good for quick rough cuts with a shot of Kool Mist or WD40.

I just haven't been able to justify the cost of a $1000+ cold saw yet. Anyone have an inexpensive one they're happy with?

Re: Wrecked Aluminium from chopsaw
 

Having used both, I think that given the option, the horizontal bandsaws would be safer. Simply put, the bandsaw is going to have less loading per tooth than a circular blade, and the potential for an accident is lessened.

However, a chop saw with a properly clamped piece, where the blade only engages it such that the cutting force keeps the piece pressed DOWN, can be perfectly safe. We had an incident this year where someone attempted to use the radial arm function of the saw, with a churro in the back, and brought the saw from out to in, such that the cut lifted the churro. This bounced around inside the blade guard before hitting the ceiling. A second incident is where I built a wood jig to hold pieces, and I didn't have quite enough downforce clamping for where the piece was relative to the blade, and it pulled the aluminum through a piece of 3/4" plywood jigging making a sound like a gunshot, and tossing the piece. Fortunately, safety glasses policies and no hands near the blade made this a near miss, but a sobering one.

For any harder metals (steel axle rods), the chop saw might also have issues, where a bandsaw would not really care, it would just cut more slowly.

So, I don't think its fair to say "you shouldn't use a chopsaw" because they are dangerous. You just need to be aware that the damage potential is greater, and mitigate the risk appropriately. If you have less strict control over the tools, and see a risk of a student (or mentor) improperly using the chopsaw on metal, you might consider a safer (albeit more expensive or less precise) method of making cuts.

Steven

Re: Wrecked Aluminium from chopsaw
 

Per my previous post:

http://www.evolutionpowertools.com/us/build/rage3.php
http://www.evolutionpowertools.com/u...n_build_us.pdf

After a go round with my Rigid saw this was what I bought.
The cuts are cleaner and obviously more thought toward cutting metal was put into it. A 4x more expensive cold saw would be even better and is my tool of choice but for a little late night tinkering this works for me.

Some of the Dewalt saws run at no load RPM near this.
Many of the cheaper saws run at higher RPM.

My other saw is a Harbor Freight bandsaw with a custom down feed system I made. There are instructions for this downfeed elsewhere on the Internet. I recommend this attachment it improves the quality of the cut and the aggravation of using the saw quite a bit.

Re: Wrecked Aluminium from chopsaw
 

There's absolutely nothing wrong with using an blade for aluminum in a chop saw designed to cut aluminum to cut aluminum.

If you clamp the part well (not the crappy little clamps that come with saw, something real strong) and don't go crazy fast through the part, you'll be just fine.

Re: Wrecked Aluminium from chopsaw
 

It's interesting to see a lot of us have converged on essentially using the same saw. A 14" blade saw designed for metal with the proper blade.

We're loving ours so far, it's a huge time saver during season.

Re: Wrecked Aluminium from chopsaw
 

Yep. I think I'm going to try to work one into the budget. Our ~$600 sliding radial arm saw is roughly equivalent (purchased by our teacher before we joined), but the clamping is insufficient and the sliding action is a safety nightmare if used on metal. Thanks for pointing me to the better version of a metal chop saw.

Steven

Re: Wrecked Aluminium from chopsaw
 

Yep the aluminum blades work like a charm

Re: Wrecked Aluminium from chopsaw
 

A vertical band saw with a blade made for metal or a horizontal band saw with a blade made for metal probably work better than the chop saw. Imo, it's very dangerous to be cutting a piece of aluminum that large on the chop saw, and I'm hoping you guys clamped it at first. I think it COULD be done with the chop saw, but I would look into getting a horizontal band saw. Those things are amazing for metal. (Of course, milling it is preferred, but good mills can use up $$ quickly)

Re: Wrecked Aluminium from chopsaw
 

It's amazing when things that are designed for a given purpose actually work for that purpose.

But yeah, that Dewalt multicutter has saved us so much time this year it's ridiculous.

Re: Wrecked Aluminium from chopsaw
 

This is the internet- everyone has an opinion and everyone is an expert. It's why we have discussions like these.

How many times have you had or heard of a workpiece being picked up and shot across a room by a circular saw? How many times has the same happened with a bandsaw or recip. saw?

Have you heard of anyone losing fingers to a circular saw? What about bandsaws or recip. saws?

You can't deny the circular saw is far more dangerous than the other two.

Therefore, it is not the best option regardless of speed or convenience.

You're going to argue this by saying "it can be just as safe as long as *** and *** and you don't ***." Well each of these *** represents increased chances of something going wrong.

Ultimately you need to put safety before speed cost and convenience because nothing brings a build season to a screeching hault faster than a student getting hurt.

Re: Wrecked Aluminium from chopsaw
 

Man, cars are a bad idea, I should just walk everywhere. :rolleyes:

Teaching proper usage of equipment and enabling students and team members to be more productive is always the best idea.

But you do need to draw the line somewhere, in this case some have chosen proper training and using equipment designed for the job, You have chosen to require less training, and addition ops.

-Aren

Re: Wrecked Aluminium from chopsaw
 

If only their was a better balance between a car and walking.
You know something that has 2 wheels and balances. :yikes:

I don't know if there are that many additional ops involved.
Even with cold saws I mill or grind the ends that are critical.
Take for example a 1-2-3 block they aren't just cut.

I think the issue is also one of expectations.
There are plenty of ways to cut aluminum but not everything needs be micron accurate.

In fact wasting time for accuracy you don't need is as much an issue as designing things that require accuracy when there are more forgiving alternatives.

Re: Wrecked Aluminium from chopsaw
 

A bandsaw requires you to use your hands to push the part towards the cutting blade. How is that better then having one hand (or both) on the cut off saw handle which is several inches away from anything that can cut them?

I've come much closer to cutting my fingers on a band saw than I ever have with our Dewault cutoff saw.

I'm not going to debate which is safer. Is it a factor that should be used in determining which tool is best for your needs? Sure. I'm just proving a point that a band saw being used normally has a greater potential of cutting fingers than a chop saw that is used properly and so I could argue that it is more dangerous than a chop saw when it comes to finger safety. I could also argue that a chop saw is more dangerous because it has a greater potential of flying debris and so it could cause harm to anyone standing in the path of the saw blade. Would it be safe to cut a round shaft on a bandsaw? NO! Would be be safe to cut a round shaft with a chop saw? Absolutely!

So why are table saws so dangerous? The user is always pushing the part towards the saw blade with his hands. This is the same as pushing the part towards a sharp moving bandsaw blade.

Re: Wrecked Aluminium from chopsaw
 

Evo Cold Saw - all I am going to say.
http://www.oceanmachinery.com/evolution_saw.htm#380 Evolution Steel Saw

Re: Wrecked Aluminium from chopsaw
 

Actual I have gone in another room & made coffee while cutting parts with the band saw. :)

A band saw will cut you just as fast a chop saw, but it is a lot less likely to cut you finger off.

Re: Wrecked Aluminium from chopsaw
 

As a shop teacher with 30+ years of history around woodworking power tools and 13 years in the classroom, I have seen accidents and results of accidents from chop saws, table saws, lathes, jointers, band saws, sanders, drill presses, and everything else. Fortunately I've not had to deal with students suffering injuries likely to change how their hands work, but I've seen that and worse happen to adults and children elsewhere. Use the right tool for the job, make sure you prep it correctly, and be thoroughly trained. Students should work within sight of a responsible adult and always check to make sure what they are planning to do is correct and safe.

Regarding bandsaws being a "safer" choice: see the meat packing industry and what they use band saws for.:eek:

Re: Wrecked Aluminium from chopsaw
 

The best $1K I ever spent was when we moved from using a chop saw with aluminum blade to a cold saw. Besides the piece of mind of knowing students fingers are likely to stay attached, the noise is vastly less. Cold saws just turn at around 100 rpm so the difference is night and day. Ours is this one from Jet.

Re: Wrecked Aluminium from chopsaw
 

If your cold saw is running at around 100 RPM it is likely a cold saw for ferrous material.

Non ferrous cold saws are up in the 2000-3000 RPM range

Re: Wrecked Aluminium from chopsaw
 

That's true, our cold saw is designed to handle steel but does a dandy job on aluminum.

Re: Wrecked Aluminium from chopsaw
 

We use a chop saw quite a bit during build season for cutting aluminum tubing, angle, box extrusion, etc. I've found this advice to be key - don't rush the cut, don't slam the blade down into the material with a ton of force; let the tool do the work.

Re: Wrecked Aluminium from chopsaw
 

No matter how careful you are if students are hand holding the aluminum you will find a typical chop saw will eventually grab the aluminum and do something scary with it. Maybe it will fling it across the shop, maybe mangle it, maybe just scare the pants off a student or maybe cause serious injury.

When we were using a chop saw for aluminum we'd have something scary happen about once a year. Thankfully no one ever got hurt but it sure got my attention. And the noise, oh the noise.

If you insist on using a chop saw to cut aluminum, please figure out a way of clamping it so students aren't hand holding it.

Re: Wrecked Aluminium from chopsaw
 

Best thing we ever bought

http://www.amazon.com/Morse-CSM14MB-14-Inch-Dry-Cut-Cutting/dp/B000IHXOKI/ref=pd_sim_sbs_hi_3?ie=UTF8&refRID=0V285P96W7YRB23 TAPCA

Re: Wrecked Aluminium from chopsaw
 

Personally I prefer the horizontal band saw for cutting stock. They include a vise to clamp the material and hands never have to be anywhere near the blade. Not it is not as quick as a chop saw but with the right blade it goes pretty quickly. Since we got ours the chop saw is only used for wood.

Re: Wrecked Aluminium from chopsaw
 

Why has no one said anything along the lines of: the blade is wrong?...

I am almost positive that is a wood blade, the teeth are spaced out FAR too much and have the end bits on them. The huge teeth grabbed the part (ESPECIALLY since it is a tube) and threw it. This is an extremely obvious safety hazard to me. I have cut more aluminum on a compound miter saw WITH THE CORRECT BLADE then I wish to count. It is extremely safe. One hand has to be on the trigger and pulling the blade down, and the other is free, but it is VERY obvious where the blade will go, especially with a laser, and I use the other hand to brace the part if needed.

Re: Wrecked Aluminium from chopsaw
 

Are you sure the blade in the original post photo is for metal? Looks like its for wood. please don't try wood saws for cutting metal!

Re: Wrecked Aluminium from chopsaw
 

Hah I beat you to that by about 11 minutes. :rolleyes:

Re: Wrecked Aluminium from chopsaw
 

We use a metal cutting chop saw; a Dewalt. We cut aluminum extrusions including 2x1 and bosch without problem. It has a clamp onboard, so the material does not lift or move around.
We had a problem this year with a terrible cut (nobody got hurt or was in danger) when somebody tried to cut 1/8" aluminum at an angle. Bad idea, and the piece had to be scrapped. We use a bandsaw for plate now.
The clamp is hard to get square and the saw is extremely loud, but in my two years on the team nobody has gotten hurt or even come close. Clamping correctly makes things much easier.

Re: Wrecked Aluminium from chopsaw
 

Looks a lot like an aluminum blade to me.

http://www.amazon.com/Freud-LU89M010...freud+aluminum

Re: Wrecked Aluminium from chopsaw
 

We've been using a wood chop saw to cut tubing, C-channel, and 80/20 for the entire time I've been in FIRST (five years I think? something like that).

But we have rules about how to use it:

Always use a secondary clamp (We use a C-clamp), make sure the part is clamped in a way where it's physically restrained (If you've got a 1x2 bar, the 2" side should be against the fence, where the clamp is putting pressure).

Your hand that's not on the handle should be at your side, or behind your back. No need for it to be anywhere near the cutting area.

Go slow, let the saw do the cutting. It should take 3-5 seconds to get through a 1010 bar of 80/20. (You can actually go a fair bit faster, but this is a good range for students, because if the accidentally go a little too fast, it's not an issue)

Bring the blade all the way down, turn it off, and don't bring it up until it's stopped spinning.

And of course, make sure you've got a proper blade for aluminum. Honestly I forget the tooth count on ours, but it's a tri-chip blade, I'd guess it's an 80-tooth.

As far as I know, we've only had one accident with that saw, and that was one time long ago where I brought it up while still under power. Either the bar expanded from heat, or slipped in it's clamp, and it caught the back edge of a carbide tooth. It broke three teeth off, and threw them at me. Luckily I was okay, they didn't even get through my shirt.

So one minor accident over five years and thousands of cuts, and that due to improper use. We've never had any issues from people using the above rules.

Re: Wrecked Aluminium from chopsaw
 

I've seen aluminum scrap ejected from a chop saw before, but I've never seen it result in injury and it never happens if you have the work piece properly clamped and you are firm and steady while cutting.

As a rule, neither 449 nor 4464 allows freshman to use the chop saw at all. Older students must have a mentor immediately present and observing. Work pieces must be clamped on both sides if possible (we just use normal c-clamps), and if it is impossible to clamp either side then a mentor must make the cut.

We have not had any safety incidents of note involving the chop saw on either team, and neither team could function without regularly using a chop saw for aluminum tube.

Remember to replace your chop saw blade regularly if it sees heavy use - the teeth do wear down, and once you lose a couple of those you can start having problems.

This is absolutely crucial. Even a clamped piece can settle slightly once the cut is made, and bringing a spinning blade back up into a piece that has moved even slightly is a bad idea.

Re: Wrecked Aluminium from chopsaw
 

Usually clamping on both sides of the blade is considered to be a very bad idea (Blade binding and all that). We have had no problems clamping with the built-in clam and a C-clamp on one side.

If you follow the "Don't bring the blade up until it stops" rule, then I don't think clamping on both sides is an issue, but I would still stick to the one side.

I always try to remember that these are skills that the students will take with them, beyond my or any mentor's guidance. And in recognition of that, I try to avoid teaching the students things like this. That is; procedures that are unsafe, and only become safe under a narrow set of circumstances.

For instance, if the student is cutting a different material, where you can raise the blade under power, and they still clamp both sides, then something bad could happen.

Re: Wrecked Aluminium from chopsaw
 

I've never had any issue with it at all (been doing it for ~7 years now), and it does a great job of ensuring that your work piece stays right where you want it.

We never let the students bring the blade up while spinning regardless of material; we find it better to keep the procedure the same.

Re: Wrecked Aluminium from chopsaw
 

I'm sure you haven't, but that's not really what I was getting at.

One thing our shop mentorship identified and focused on is consistency. Because we all, as experienced metalworkers (Some professionals, some amateurs) have different ways of doing things. And those methods are safe on their own. But, if you mix-and-match different parts of them, somebody could definitely get hurt.

So before doing any safety training this last year, we sat down and laid out exactly what method we were going to teach the students, and we tried to ensure it was the method that follows "best practices" or at least general widely-followed practices. That way, if our students go on into machining, like I did, they won't have to un-learn anything we taught. And we don't have to worry about them accidentally mixing-and-matching our methods, and those that are used out in industry/education.

I mean I don't want to tell you how to mentor or anything, just my $0.02.

Re: Wrecked Aluminium from chopsaw
 

Did you by chance document this in a form that you would be willing to share so that others may be able to benefit?

Re: Wrecked Aluminium from chopsaw
 

We have a master tool and safety document from a few years back, and last year we only edited the relevant parts. This summer I want to do a full re-write, with more procedural instructions (As in; "This is step 1, this is step 2," etc). Right now it's organized more as rules, rather than a procedure. (A member from Team 1086 Blue Cheese posted this a while back, and I think it's great.)

Here's our master document.

The first 50 pages are all tool info, you can skip those ;)

We then have the students take an online test with questions on those rules, which the have to pass with a 100% score (retakes allowed). And then we do mentor-guided hands-on training in the shop, and the student gets signed off on a list.

Re: Wrecked Aluminium from chopsaw
 

Here is our solution to chop saw safety.

Big piston is about 140 pounds of force, small piston is about 40 pounds. Clamp is actuated by a foot switch toggle. Anything bigger than 4" in a dimension gets cut with the band saw.
We also added a pneumatic brake to the blade, if the blade is off the solenoid fires and it pushes the side of the blade and stops it in about 2 seconds. You must depress BOTH buttons on the 2 handed handle to turn it on, both hands must be used.



The main thing I have noticed that causes parts to get ejected are small loose pieces getting snagged by the blade if it is brought up too soon. That is why we clamp both sides.

This thing has been amazing this year, 3 HP 3 phase motor. No injuries from the saw. And it only cost $95! plus some parts, but still way cheap. I love auctions.

Re: Wrecked Aluminium from chopsaw
 

Cylinder not piston. Sigh....,,,

On the other hand. That's pretty cool.

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.

Re: Wrecked Aluminium from chopsaw
 

We have used these blades to cut aluminum extrusion on our 12" Dewalt miter saw. I highly recommend them for this purpose.
https://www.amazon.com/gp/product/B000FXWCGM/
https://www.amazon.com/gp/product/B00008WQ39/

Re: Wrecked Aluminium from chopsaw
 

I'm a fan of this blade for our 10" miter. We've cut aluminum(6061, 7075), plastic(polycarb, acrylic, PVC), and wood on it. Super clean surface finish provided your work is properly clamped down.

Re: Wrecked Aluminium from chopsaw
 

I'd have to triple-check to be sure, but I believe it was this blade: https://www.amazon.com/Oshlun-SBNF-1...THMH0DNWDXGHN4

We like it so far, cutting 8020 with it primarily.

I have cut stainless, aluminum, steel, and titanium with the blade that came on the saw with no issues at all, leaving a nice surface finish and few or no burrs.

To those continuing to use high-RPM chop saws that are nominally designed for wood: please carefully consider the safety risks being taken to save about $420 bucks (<cost of 5 Talons).

Re: Wrecked Aluminium from chopsaw
 

I just put the 7-1/4" version of the second one in our Craftsman saw yesterday to chop away the holes from some disassembled robot parts so they are again stock for short pieces come build season - easiest and smoothest aluminum cuts I ever made (various extrusions, mostly 6061 and 6063). No flashing, just sharp corners to deburr. Have not done any miter/bevel cuts yet, but anticipate no issues.