Fishmouths??

   / Fishmouths?? #1  

Rancher Ed

Gold Member
Joined
Apr 22, 2011
Messages
294
Location
Texas
Tractor
2008 Kubota M7040 4WD w/loader, 1979? Mitsubishi D2600 4WD w/loader
I have been thinking about maybe making a couple gates out of some old pipe we have and have been wondering what the best way to make the fishmouths? (that doesn't sound quite right but I think that is what it is called) on the ends of the pipe so they can be welded to a different piece on pipe.

We have a drill press but its slowest speed is ~750rpm so I am guessing it won't work. We also have drills and 4 1/2" grinders. What would be the best way to go about doing this?

Thanks, Ed
 
   / Fishmouths?? #2  
If you're going to do it with hand tools, this is a nice template maker. Plug your numbers in, print it out, cut the line, wrap around your pipe, mark, and cut / grind.

Tube Coping Calculator
 
   / Fishmouths?? #3  
What I've done is just cut a shallow V in the end of the pipe and using 6013 rods to weld. Not necessarily the prettiest joint but it holds.

Good luck.
 
   / Fishmouths?? #4  
I've made fish mouths with a hole sale in my drill press, and I've cut them out with an angle grinder. I usually keep one grinder with a narrow curf cutting disc in it and another one with a grinding disk. It's fairly quick to cut the V with the cutting disc and then grind out the rest of the profile.
 
   / Fishmouths?? #5  
I've never done it, but I have read where you can cut fish mouths with your chop saw. A guy posted these angle for the size pipe you're working with on another site.

Pipe / Tube bevels

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*
 
   / Fishmouths?? #9  

Yes but there's a few precautions you need to take. The shaft spins on a bushing. You need oil or grease on the bushing or it will get slack that will decrease accuracy. The hole saw makes lots of small metal filings that get attracted to the grease. It's better of you mount it on a drill press (I used a 1/2" hand drill with it clamped into a vise). Also something like WD40 is needed to lubricate the saw while cutting so it will last.

So keep it greased and the grease clean of dirt and metal and it will work great.
 

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