Chop saw notching 101 (With pictures)

[TNToy]

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...

[TNToy]

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.

[TNToy]

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.

[ironpig70]

thanks for this info. will definetly be used

[TNToy]

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.

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

[Ali]

thanks for the tip!

[Cue-Ball]

Well done. :bookmarking thread:

:Golfclap:

[35xj]

good stuff. since our notcher took a shit i've been doing the same thing with either the sawzall or the porta band. works great!

[5trucks]

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

Big Sexy

[FatCity]

Originally Posted by 5trucks

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

[Nordic1]

That's good to know (I'm to cheap to buy a notcher) thanks!

[TheRipper]

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

Originally Posted by Nordic1

That's good to know (I'm to cheap to buy a notcher) thanks!

How could you be to cheap I bartered with HF and got mine for like $30..

[W_B]

Nice post.. good info..

guess it's time to go build that cage I've always wanted!!

[aloharover]

Originally Posted by TNToy

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.

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

[Tippy Tim]

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

[Grnscru]

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?

[TNToy]

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.

[KI5KA]

Originally Posted by TNToy

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....

Great tip! thanks

[jasonmt]

Originally Posted by TNToy

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.

Like I said in the below post "If you are really bored" or you are stuck in the middle of a refinery in a hole trying to figure out how to stub on a 4" pipe to a 4" pipe at a 40 degree angle would I bother with the formula.

For small stuff (under 2") I generally just eyeball it and then hit it with a cone stone on the grinder to get it to a acceptable fit.

http://www.pirate4x4.com/forum/showp...2&postcount=44

[TR]

heres a program that prints out templets that you wrap around the tube
http://home.tallships.ca/mspencer/winmiter.html

[j13l]

A subject which returns regularly is the "Pipe/tubing Notcher with chop saw".

Wishing to learn to program with Web, I made this small script. (Javascript, PHP ...).

http://snip.awardspace.com/

Good notching.

[Trailer Rails]

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

With the program above it spits out 45* for each cut. Whick one is right? I am thinking 28* is right because I rember trying to chop saw notch and I cut both angles at 45*. The tube was nowhere close to fitting together correctly.

It is a nice little program. I think it needs some tweeking.

[jasonmt]

Originally Posted by Trailer Rails

With the program above it spits out 45* for each cut. Whick one is right? I am thinking 28* is right because I rember trying to chop saw notch and I cut both angles at 45*. The tube was nowhere close to fitting together correctly.

It is a nice little program. I think it needs some tweeking.

If you punch in 1.75" for the OD and 1.75" for the ID it is going to give you a 45 degree response.

If you punch in 1.75" for the OD and 1.51" for the ID assuming that you are using 0.120"WT tube you get a "base angle" of 60.2/29.8 degrees.

[j13l]

3 values are needed for the program to work.

od for the outside diameter of the main tube.
Id for the inside diameter of the notched tube.
angle for the connecting angle of tubes.

You will obtain 2 angles of cutting.


The table is a bonus summarizing some angles of connecting.

[Trailer Rails]

Ahhh, thanks, sweet little program. It helps if I read the direstions huh?