Cutting EMT

[joshuabardwell]

I have a project that I may be doing soon that will involve cutting about 250 pieces of 3/4" EMT. The last time I did this, I used a 14" abrasive chop-saw, which worked really well in a lot of ways, but one thing I didn't like was how long it took. I could only cut one piece at a time and each cut took maybe 5 seconds, plus the time to set up the next piece in the jig. Really inefficient.

I have one of these Diabolo metal cutting blades that I originally got for cutting corrugated metal roofing. It says right on the side of the blade that it is for EMT, so I am sure it will do the job, but given that the blade is $40 a pop, I am not so sure it's the right choice. 14" abrasive wheels are maybe $7 each, and if I recall correctly, I will use 2 or 3 of them on this job.

My question is, if you have one of these Diabolo metal cutting blades, what kind of life can I expect out of it cutting EMT like this? I would really like to be able to just line up a bunch of pieces of EMT, clamp a board across them, and then run a circular saw down a straight-edge to cut tens of pieces in a single go. It would save so much time! But if I'm going to burn out this $40 saw blade in the process (or, god forbid, more than one!), I think I'll just suck it up and use the chop-saw.

In case you're curious, the project is building a geodesic dome. You can read more about the first time I built a dome here.

 

[BHD]

I have a Dewalt cordless metal cutting saw that I use for this purpose,(Cutting emt conduit) and it is still on it first blade, and on the diablol blade, I cut plate steel up to 3/8" and have cut a lot of running feet in projects, and they last a good time, I think on conduit they would last a very long time as it is very thin steel,

 

[chim]

At work we often cut hundreds of pieces of EMT the same length. For that we take bundles of 100 feet and wrap duct tape around the bundles at the cuts. The bundles are clamped in one of the horizontal band saws and the conduit is cut 10 pieces at a time. For burr removal we then run the pieces through an out-of-print Ridgid prep machine.

 

[LD1]

Got access to a gas powered abrasive saw. (like a concrete saw)??

If so, you could line them up like you plan on doing with the circ-saw, and cut several at one go.

 

[Soundguy]

a radial arm saw with an abrasive or that metal cutting blade will be fine.

emt is thin soft stuff.. shold not tax that metal cutting blade much at all.

heat kills blades more than anything..

 

[LD1]

Forgot, another option would be a porta-band.

Once they are all marked and lined up, you can zip through them rather quickly.

If you dont have a porta-band, maybe this is a good excuse to get something from the wish list

 

[jwmorris]

I would bundle cut them, as many as I could at once. If I couldn't use one of my automatic horizontal band saws I would use the roll in or as a last ditch I have a portaband and table that I have modified for cutting parts with adjustable pressure and auto cut off that works too. So it at least can be cutting while you debur.

 

[joshuabardwell]

Thanks for everyone's input. It sounds like the Diabolo blade is going to be the go-to. Unfortunately, I already am using this project as a justification to buy an air-over-hydraulic press, so a porta-band is out for the time being. The last (and only other) time I made a dome, I used a friend's press, so that's the one tool that's required for the job that I don't already own. The only other tool I have that might cut the EMT is a reciprocating saw, but it's battery powered, so it will be more trouble than it's worth. I will have to wait until the next time somebody buys a dome from me to buy a band saw.

EDIT TO ADD: Anybody want to buy a geodesic dome?

 

[Soundguy]

i'd use any of the other items mentioned before using a sawsall. IMHO.. it's akin to a chainsaw when you look at cut quality and accuracy..

 

[LD1]

i'd use any of the other items mentioned before using a sawsall. IMHO.. it's akin to a chainsaw when you look at cut quality and accuracy..

Yep, not to mention slower, any I have never had much luck getting them blades to last. At least not as long as other cutting methods.

 

[Soundguy]

wood blades I do ok with.. the metal blades.. they seem to go fast due to heat.

i even buy the good blades.. not the harbor freight cheapies... lately i have gotten the long ones and get 3x the use out of it cutting small items, as the cut area only wears a part of the blade about 2" long due to stroke. thus I can get about 3 cut areas out of a long one.. still not my choice of straight metal cutting.

i use mine more for demo work cutting thru a stud where i know i might hit a nail or anchor bolt shaft.

in dire cases i have used it to cut soemthing i could not torch due to location or heat.. etc..

 

[Stimw]

Harbor Freight sells visegrip like chain clamps.
With two of those you could bundle, clamp and use the chop saw for a dozen or so at a time.

 

[thecnwcaboose]

What? no one mentioned a hacksaw? Ive been cutting conduit for years with one...

thought Id mention it just for the hack of it.....

 

[CNC Dan]

Don't forget that the length of the tubes isn't critical, but the distance between bolt holes is.
Use a jig that locates off of the first hole to position for the second hole.

If you've done this before you probably already know all this.

 

[Soundguy]

What? no one mentioned a hacksaw? Ive been cutting conduit for years with one...

thought Id mention it just for the hack of it.....

i've cut it with a roller style copper pipe cutter. worked nice. was slow as watching ice melt in a refer though..

 

[joshuabardwell]

i've cut it with a roller style copper pipe cutter. worked nice. was slow as watching ice melt in a refer though..

With about 250 cuts to make, I'll pass.

 

[Soundguy]

i hear ya!

 

[k0ua]

i've cut it with a roller style copper pipe cutter. worked nice. was slow as watching ice melt in a refer though..

I did that.... once.. I use my bandsaw now. Not the fastest but makes a nice square clean cut, and it is only a few seconds.

James K0UA

 

[Soundguy]

for the small amount of any tube or pipe i cut.. I just chopsaw it... I don't even keep the radial arm saw out inthe open anymore.. it's on a rolelr bench burried somewhere..

 

[grsthegreat]

Yep, not to mention slower, any I have never had much luck getting them blades to last. At least not as long as other cutting methods.

I have a portable band saw...its hand held (one handed). and after 10 years, im still on the original blade. I cut alot of 2", 3" and miles of 1/2" and /4" emt with it. It also blasts thru RIGID pipe.BettyMills: Heavy-Duty Deep Cut Porta-Bandｮ Saws - DeWalt 115-DW328. mine is LIKE this, but made by ridgid.