Welding round tube...Help please

[chopitrakeit]

Good info here: Tube work.
Also just google "Tube Weld Fishmouth".
Also look at some sites that deal with race car building ie roll cage construction.

 

[JoeL4330]

Big hammer, flatten end on intersecting piece, weld

 

[Blagadan]

Or if you have a 4.5 inch grinder, you can cut in the fish mouth on the end of the tube roughly first, then when you are pretty close, you can get a marker and scribe in exactly. Better to spend the time and get a perfect fit, makes for a nicer weld in the end.

Depends on how many you need to make I guess. If only a couple, grind em out. If 20 or more, get the HF hole saw tool. If 50+ I'd get a miller cutter and use in a pillar drill with a good XY table (AKA milling machine...lol)

 

[chumly2071]

One thing to add with the holesaw route... Do not leave the "knife edge" point on the end of the tube you just coped. Grind it back until you get a full material thickness all around the edge. This gives you a lot stronger weld.
When using the holesaw method, I typically make a mark 25% of the tube diameter from the end of the tube being coped, and then when I position it in the notcher vise, I make this mark tangent to the holesaw. This gives you a good cope, not requiring the grinding (except for a little deburring), and also actually cuts faster as the holesaw is not having to remove so much material during the cut. Use a slow spindle speed, and some cutting oil. Another thing to mention about the HF nothcer, is the bushing for the cutter spindle can wear out and get "wobbly", leading to loss of teeth on the holesaw. Sometimes too, the holesaw on the HF version will not be centered over the tube when clamped in the vise (HF quality thing). For the money vs. usefulness, the HF nothcer is a good buy.

For a lot of repetitive notching, it is hard to beat the chopsaw method for speed, but does take some getting used to.

If you're doing a joint with several tubes converging at a node, then the Pipemaster brand templates are a good start, albeit a little pricey.

 

[tommu56]

cityfarma


Here is a link to pipe layout that I use tee / saddle is around page 20 or so

http://www.globalsecurity.org/military/library/policy/navy/nrtc/14251_ch3.pdf

tommu

 

[chumly2071]

That is a really good reference tommu56!!!

 

[cityfarma]

That is a really good reference tommu56!!!

Ditto.

I have only got back to this thread today and thank all who have added comments. I will be taking a close look at some of the ideas and links.

Cityfarma.

 

[cmuncy]

I love the guys over at Pirate4x4.Com - The largest off roading website in the world. as they think like we do:

Chop saw notching 101 (With pictures) - Pirate4x4.Com Bulletin Board

Take a look at the link: pics and descriptions:

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

I just found a neat little program that will print out a template that you can wrap around your pipe in order to get the correct notch:

Pipe ans Tube Joint Software

And here is an online program you can use. If you enter the ID and OD of the pipes, it will give you the correct angle to cut:

SNiP Sawing Notch in Pipe

(btw - these sites are work safe and pop-up free)

 

[Cap-n-Cray]

I used this jig for tube railing job. Works well, and very precise, but expensive.

Cary

 

[Sandlot]

I have been thinking about this little tool. Anyone have one?

Harbor Freight Tools - Quality Tools at the Lowest Prices