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Hi,
I am building a wet tumbler and using PVC for the tumbling drums. I have 6" & 8" PVC pipe. The 6" pipe is schedule 40 and I bought Cherne mechanical plugs for them. They fit and work perfectly. Now my problem. My 8" is schedule 80 and the mechanical plugs I bought are too big for the schedule 80. They are designed for schedule 40.

Schedule 80 and schedule 40 have the same outside diameter. The schedule 80 is thicker pipe (made to be pressurized). I have a router but no router table.

What I need to do is increase the inside diameter of the last two inches of the pipe to the same as schedule 40. I am guessing I will only need to remove 1/4 inch or less.

ANY suggestions as to how to accomplish this? This pipe is about $74.00 a foot so I have to be sure I don't mess it up.

Thanks in advance for any and all input
Doug
 

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Hi,
I am building a wet tumbler and using PVC for the tumbling drums. I have 6" & 8" PVC pipe. The 6" pipe is schedule 40 and I bought Cherne mechanical plugs for them. They fit and work perfectly. Now my problem. My 8" is schedule 80 and the mechanical plugs I bought are too big for the schedule 80. They are designed for schedule 40.

Schedule 80 and schedule 40 have the same outside diameter. The schedule 80 is thicker pipe (made to be pressurized). I have a router but no router table.

What I need to do is increase the inside diameter of the last two inches of the pipe to the same as schedule 40. I am guessing I will only need to remove 1/4 inch or less.

ANY suggestions as to how to accomplish this? This pipe is about $74.00 a foot so I have to be sure I don't mess it up.

Thanks in advance for any and all input
Doug
bearing guided rabbeting bit and a router table..

 

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PVC will get very hot when routing and it can melt onto the bit making a real mess of things. Also the bit will like to take chunks out of the plastic and throw them everywhere. You'll need to slow your router down when you try to cut the rabbit. The whole idea of using a router to expand the inside diameter is interesting.

I might try a couple of things. First would be to mount 2 pins to rub on the inside of the pipe above the cut to hold the router bit the correct position for the rabbit. But I would try it on a scrap of other pip first.

Another thought I had was to cut a circle into a board that the 8" pipe will fit into so you can rotate it easily. Mount the router at the correct position on the board with the bit sticking through at the correct position to make the cut. Make very small cuts with each pass.

My experience with PVC is it makes pretty good shrapnel if the bit is allowed to grab it. Good luck.
 

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Is there a bit long enough to route 2" deep? Might try making a reducer out of plywood rings and stack them up after they are cut out. Or buy a coupling and make a plywood reducer to fit inside. Or if the OD's are the same use the coupling and put the 80 in one side and the 40 in the other.

Herb

What kind of ends does the pipe have? Bell? Straight?
Make wooden ends to plug the pipe?
 

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Or caps for the outside. Two test caps with gear clamps would be a simple solution. Or couplings with one FIP end on each, plus threaded plugs.
I'd go the plumbing fitting route before trying to machine the PVC.
 

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cut two circles out of 3/4 ply for each end 1/16 less than pipe id. Find 1/4 inch cross section oring with the od as close to the pipe ID without being larger (ASA568A-441)Cut a 3/16 x1/16 deep rabbet on the od on one side of the circlesDrill 1/4 inch hole in center for 1/4 carriage bolt. put two circles together with the rabbets facing each other. bolt together with 1/4 inch carriage bolt. Stretch the oring so it fits in the groove fromed by the twp rabbets. Slip in the ed of the pipe and tighted the bolt to squeezw the oring.

Another approach would be to make two taper wood plugs the will start into the pipe. Drill a 1/4 hole in the center of each. Get a piece of all thread long enugh to fit through the pipe and plugs.
 

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I tried finding 8" fittings for the PVC....good luck with the 8" availability. It's basically a municipal water supply, and maybe some industrial app., situation.
You'd have to go to a glue on cap on one end and a glue on coup. with a FIP thread at the outside end, with a threaded plug at the outside end. With a round slick interior there won't be much tumbling happening.
The coupling and cap have the same outer diam. so that's what would ride on your drive roller.
 

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The only safe way to cut the inside of the pipe is on a lathe,either wood or metal. Maybe a machine shop could chuck them up and turn them to size with boring bars. and I suppose they could be mounted on a wood lathe and cut inside like a bowl too.

Herb
 

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sch80 will machine the same as sheet goods...
a router table along w/ a bearing guided bit should do it...
rabbet or straight bit w/ several different dia bearings so the rabbet can be cut in stages.....

a 1'' dia straight bit w/ a ¾'' bearing will give you an 8th inch deep cut...
same bit and a ½'' bearing will give you a ¼'' cut...
but taking a ¼'' in one shot would be nuts...
use 13/16 and 9/16'' dia bearings if need be....
 

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How about this; Make a template from a piece of 3/4" plywood or MDF larger than the pipe and cut a hole in the center to match to hole you need plus 1/2 of the difference between the bit diameter and a guide bushing. Attach this to the top of the pipe using locating blocks on the underside of the template. Get a long straight bit (I recommend at least 3/8" diameter with 1/2" shank) and take progressively deeper cuts until you get to the depth you need for the plugs. Go slow and don't burn the pipe.
 

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The test plug seems to me to be the best solution if you can find a place that carries it. Second I think the idea of chucking it up in a lathe and using a scraper to hollow it out like doing a hollow vessel. If you have or could get access to a wood lathe I think you could probably do something with a regular check to secure the pipe section, although I don't know how long it will be so that might preclude the lathe. If you turned a piece of wood that was > 8" by cutting a tenon on the end and then cutting it down on the outer end to press fit into the pipe or turn it close in diameter and glue in with silicone at end that would be easy to break free and clean out later. If it's very long it might wobble though without support.

If you go the router route I think you could use a flush trim bit that is 2" long-those seem to be better to me than a rabbetting bit as I am not sure if they make rabbetting ones 2" so you'd have to do multiple cuts. I know I've seen those on amazon for less than 20.00. You'd have to secure the pipe and router though and rotate the pipe in a cradle cutting light cuts til you achieve what you wanted. Cradle should be easy, you could just cut an upside down triangle in a piece of wood to support it, then figure out how to secure router horizontally somehow.

Interesting problem-let us know what you decide to do and how it works out. I recently had an unusual project for a woman who wanted to cut several duck pin bowling balls and bocci balls that belonged to her deceased mother so she could incorporate those momentos into something she could use and see daily. It was a fun but messy project that in the end required a unique jig that was simple but took me a while to think of it. If anyone is interested in pics of that I took shots, could be handy if you ever have to cut any kind of round object. So let me know and I'll post if interest.

Good luck.
 

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Im a little confused. The plastic pipe industry chart states the ID of 8" sch 80 PVC pipe is 7.565.It sounds to me that you have the wrong plugs. It would probably be safer to make plugs out of plywood than to trying to use a router on the end of a peace of pipe.
 

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sch80 will machine the same as sheet goods...
a router table along w/ a bearing guided bit should do it...
rabbet or straight bit w/ several different dia bearings so the rabbet can be cut in stages.....

a 1'' dia straight bit w/ a ¾'' bearing will give you an 8th inch deep cut...
same bit and a ½'' bearing will give you a ¼'' cut...
but taking a ¼'' in one shot would be nuts...
use 13/16 and 9/16'' dia bearings if need be....
Think you can could get 2" hi out of that bit ,Stick?
Herb
 

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Discussion Starter #19
Hi,
Thanks for all the input fellows. Some great ideas for sure. Found a friend on a accurate shooter forum who lived close and owns a metal lathe. He called yesterday and said they are ready to go.
Again thanks for all the input
Doug
 

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Hi,
Thanks for all the input fellows. Some great ideas for sure. Found a friend on a accurate shooter forum who lived close and owns a metal lathe. He called yesterday and said they are ready to go.
Again thanks for all the input
Doug
Good Show! Sounds like you made the safest and best decision.
Herb
 
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