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Chop Saw tube notching exposed!

BadDog

BadDog

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I like many others do most of my notches (tube fish-mouth) using a chop saw, even though I have a "hole saw notcher" and plasma cutter. However, I pretty much guess at how it needs to be cut. Sometimes it works, sometimes I grind a while, sometimes I fill a 1/4+ gap... Recently on PBB there was a thread about how this is done more precisely. The best post was by "tigweld" on PBB and is quoted below. After the quote is a link to the whole thread. I thought this was just too good not to post here (and make it easier for me to keep up with it too!)
tigweld:

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.

What if I want an 15* joint with my 1.75" tube???? You must start with your base angle, witch 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.

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 diffrent 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*
Click to expand...

Full thread on PBB.
 
That is some baddass information there. Believe it or not, I actually understand that and can't for the life of me think of why I didn't think of notching like that a long time ago instead of just using my angle grinder to make the notch after using the bandsaw to cut the angle :doah:
 
I must admit that does work rather well. After doing my bed and exo last January with a holesaw notcher I moved into this method of notching and it was much better. I used to get so frustrated with the holesaw notcher that about every 10 notches I would throw it across the garage then go in the house for an hour to calm down... But the chop saw was still slow and required some grinding was loud (I have sensitive ears and loud things bug me and give me headaches). I bought a bandsaw to use for a chop saw since I couldn't stand the noise anymore and havn't had the chop saw out in probably 8 months now. My new notcher:

IMG_1028.sized.jpg


Notches from 0-90* in seconds :D ;)
 
willyswanter said:
I must admit that does work rather well. After doing my bed and exo last January with a holesaw notcher I moved into this method of notching and it was much better. I used to get so frustrated with the holesaw notcher that about every 10 notches I would throw it across the garage then go in the house for an hour to calm down... But the chop saw was still slow and required some grinding was loud (I have sensitive ears and loud things bug me and give me headaches). I bought a bandsaw to use for a chop saw since I couldn't stand the noise anymore and havn't had the chop saw out in probably 8 months now. My new notcher:

IMG_1028.sized.jpg


Notches from 0-90* in seconds :D ;)
Click to expand...

tHIS i THINK WOULD BE THE IDEAL SETUP ALTHOUGH MOST OF US DON'T HAVE THE ROOM OR THE FUNDAGE FOR A LATHE:blush:
 
yeah, i was following that thread over there... very usefull info. Interesting that some people who fab a lot and can definitely afford real notchers etc have gotten good enough with the chop saw method that they dont even bother with anything else. Pretty cool since a chop saw can definitely be had cheaper than a good notcher.

j
 
That lathe method is great unless you are using thin wall tubing with deep notches. The thin wall tends to bend at the tip when you get deep. You have to cut the notch, then file down some of the tip, then cut some more. It works great. I built a jig that pretty much looks exactly like the one shown. I always wondered why you can't buy those to mount up to your tool post.

-Chris
 
Sure, works great; assuming you can afford, have room for, and know how to use a lathe... ;)
 
Chop saw tube notching

Nice quote from tigweld. Can't wait to try it out. I'm building a full cage and am new to this type of work.
 
Great info there guys! But that would take all the cursing and getting pissed at the tube, out of the whole cage building experience! :D
 
Back in my Mini-Baja days I could notch tubes like that on the bandsaw faster than anyone else could do it with a hole saw. It's so much easier for small angles too, especially since most notchers only go to 60*.
 
Check out " Williams low buck tools" ,they have a notcher that works good and is affordable. Do a search for it !
[I am not related to the peoples.]
 
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All i have ever noched tube with is a home made chop saw my boss made.

he had been cutting on it for years,(making railings) when a guy tryed to sell him a nocher he said he would buy it IF it was better or faster them him.

the salesman said he dident need it!

once you do it for a bit you will have the hang of it and will be fine.
 
holy old thread batman.....


I chopsaw about 80% of my notches.....
 
Again why I started a machine shop to support the Brotherhood :waytogo: I will get there is the plan.
 
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