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Discussion Starter #1
search terms: chop saw chopsaw abrasive cuttoff 14" notching notch tube 1.75 miter coping fishmouth fish mouth hole saw

This is a recurring topic around here. I snapped a couple of pictures while doing some cage work today so we'd have somewhere to point anyone who asks from now on.

First, a brief pictorial of a basic right-angle notch. That is 1-5/8" tubing in these pictures...









 

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Discussion Starter #2 (Edited)
Next, what angle do you set the chopsaw to? Hint: It usually takes a pair of cuts between 20 and 30 degrees for a 90-degree "T" joint like the one in the above picture. Using two 45 degree cuts seems to make sense as a place to start, but is actually FAR too much and will leave large gaps if you try it.

I've seen this posted by various people on here so I don't know who to credit for posting it on PBB first. But here's the info:

Here is one from Marc Googer on www.Offroadfabnet.com :

The chop saw method, if understood, is a science. With known tube size and joint angle, tube can be notched with great accuracy. The notch is achieved by cutting two opposing angles on one end of a piece of tube, to form a point. The cross-section of this cut will be an elliptical cut due to the shape of the tube. Changes in both of the two angled cuts must be made for the intersection angle and the size of the two tubes being joined. The only real limitation is the max angle of the chop saw.

You start with what I call the base angle. This is the angle of both cuts if the joint was 90*. For an example, I am fitting Two tubes together that are both 1.75", at an 90* joint. The base angle, or the angle of both cuts is 28*. These two cuts must meet at a point, and the point must also be centered on the tube.

Remember your base angle will change with the tube being cut and the tube that you are fitting to.

Here are a few examples of base angles...

2.0" to 2.0" tube, base angle of 30*

1.75" to 1.75" tube, base angle of 28*

1.5" to 1.5" tube, base angle of 26*

1.25" to 1.25" tube, base angle of 22.5*

1" to 1" tube, Base angle of 20*

Now to fit different size tubes together

1.75" to 2" tube, base angle of 25*

1.75" to 1.25" tube, base angle of 45*

1.25" to 1.75 tube, base angle of 20*

1" to 2" tube, base angle of 12*

What if instead of a "T" joint, I want the notched tube at a 15* angle with my first 1.75" tube???? You must start with your base angle, which was 28* for 1.75"(remember above), and subtract 15* from one cut, and add 15* to the other cut to form a perfect notch. So now I must make a 13* cut and an 43* cut with the point centered on the tube. Perfect coped joint, with no grinding.

Written by Marc Googer
[Edited slightly for clarity by TNToy]
I used this to setup the cuts on the 1-5/8" tube in the top pictures (27* cut) and it came out very well. :)
 

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Discussion Starter #3 (Edited)
Last tip for now:

SAVE YOUR EMPTY PAPER TOWEL ROLLS!


These thin cardboard tubes are almost the same diameter as a 1.75" piece of tubing. Notch tricky angles in the cardboard with scissors until you get it perfect. Then slit it lengthwise and slip it over the tube & copy it. It's a whole lot faster than notching the same tube 3 times. Plus it's free. ;)

You can get at least 5 notches out of one cardboard tube if you're careful.

:D :D :D
 

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Discussion Starter #5 (Edited)
No problem. We just plain needed a good pictorial. I used it for the first time yesterday, and will probably never borrow Dibble' JD2 notcher again unless the chopsaw dies or I've got a REALLY funky notch. This is so much simpler, easier, and definitely faster. I'm loving it so far. :D

Feel free to add any other info you've gathered using this technique.
 

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If i remember correctly, Eric from FatCity built all his rigs with the chopsaw notcher. I know he did with my scout.

Big Sexy
 

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5trucks said:
If i remember correctly, Eric from FatCity built all his rigs with the chopsaw notcher. I know he did with my scout.

Big Sexy

With a lot of experience you can make every angle of cope no matter how extreme, without the use of a grinder, but I've been doing this for 15 years or so now.

Important and most commonly over looked by many is the practice of deburring your tubes after you've coped, it will decrease blood shed and increase the look of profesionalism, and can also effect your weld (sort of)

Eric Filar
 

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Good job I use my chop saw more than my notcher sometimes and grinder of course.

Nordic1 said:
That's good to know (I'm to cheap to buy a notcher) thanks! :laughing:
How could you be to cheap I bartered with HF and got mine for like $30..:flipoff2:
 

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TNToy said:
Last tip for now:

SAVE YOUR EMPTY PAPER TOWEL ROLLS!


These thin cardboard tubes are almost the same diameter as a 1.75" piece of tubing. Notch tricky angles in the cardboard with scissors until you get it perfect. Then slit it lengthwise and slip it over the tube & copy it. It's a whole lot faster than notching the same tube 3 times. Plus it's free. ;)

You can get at least 5 notches out of one cardboard tube if you're careful.

:D :D :D
No shit, that is a great tip right there. Thanks.
:D
 

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space saver

Thanks for the good ideas. My garage doesn't have room for more tools. The more ways I can use the ones i've got the better
 

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I am still a little confused on how you achieve the base angle. I try to figure it out each time I see a post about chop saw notching and have yet to figure it out. I am probably just trying ot hard to figure out a simple solution. I know there are quite a few base angles listed above, but what if I am trying to fit two pieces of tube together that are not listed above?
 

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Discussion Starter #17 (Edited)
Start with the indicated angles for the closest sizes listed... and then notch a short piece of scrap or a paper towl tube with scissors. In other words, trial and error, buddy. :)

There's a mathematical formula Jasonmt posted in one of the chopsaw-notch threads... but I'm not that smart nor patient. If you're off by 5 degrees (hell, the chopsaw has less accuracy than that to start with) a tap or two with a grinding wheel will fix it pretty quick.

Something else: I bought a couple pieces of foam pipe insulation to pad my cage. You know, the stuff they tell you never to use to pad a cage? It's $2 for a 6-foot section, around 1.5" thick, and easy to cut. Might be a good thing to use as practice-notching foder if you don't have a paper towel tube or toiler paper tube handy. :)
 

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TNToy said:
Last tip for now:

SAVE YOUR EMPTY PAPER TOWEL ROLLS!

These thin cardboard tubes are almost the same diameter as a 1.75" piece of tubing. Notch tricky angles in the cardboard with scissors until you get it perfect. Then slit it lengthwise and slip it over the tube & copy it....
:D :D :D
Great tip! thanks:)
 
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