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PVC pipe boring question from a newbie

mooserov

Aluminum
Joined
Feb 6, 2021
I have a job coming up where I need to bore out a 16" long piece of 14" OD PVC pipe. Finished ID needs to be between 13.5" and 13.75" I have an old 16" swing monarch and I was wondering how to approach this? I am looking at an 18" boring bar from McMaster that takes 1/2" square hss inserts. I can flip the part around and finish from the other side, the tolerance is not tight at all.
Is this a good idea or am I on the wrong track?
Thanks in advance.
 
I have a job coming up where I need to bore out a 16" long piece of 14" OD PVC pipe. Finished ID needs to be between 13.5" and 13.75" I have an old 16" swing monarch and I was wondering how to approach this? I am looking at an 18" boring bar from McMaster that takes 1/2" square hss inserts. I can flip the part around and finish from the other side, the tolerance is not tight at all.
Is this a good idea or am I on the wrong track?
Thanks in advance.
You answered your own question.
 
I have a job coming up where I need to bore out a 16" long piece of 14" OD PVC pipe. Finished ID needs to be between 13.5" and 13.75" I have an old 16" swing monarch and I was wondering how to approach this? I am looking at an 18" boring bar from McMaster that takes 1/2" square hss inserts. I can flip the part around and finish from the other side, the tolerance is not tight at all.
Is this a good idea or am I on the wrong track?
Thanks in advance.
Yep. Do what you said in your first post. Long boring bar. You could make your own relatively easily - otherwise just buy it.

Sent from my SAMSUNG-SM-G891A using Tapatalk
 
I wouldn't even buy a real boring bar. A piece of 1 X 1-1/8 pto shafting and a clamp for the tool bit would do just fine.

But then, I've got that sort of stuff just laying around in the shop...
 
I'd suggest that you bore one end about 1/2" deep, enough to fit a steel plate or even a wooden disk to reinforce the PVC so you can chuck it firmly and not have it pop out of the chuck on you.
 
Good plan. PVC, especially in that size, is going to "give" and "squirm" like crazy.

I bet just getting that small section bored will be harder than you think unless you use a 6 jaw, or first make a filler for the original ID to clamp on.

I'd make the filler, but I do not have a 6 jaw that big.
 
steady rest, cobbled together from wood or metal will be worth the effort.

Unless you happen to have one large enough ;-)
 
That is going to be really thin wall, not sure the ID will be consistent even at the low end. PVC tends to go oval when boring thin sections. At that length a steady is a must. I have bored short sections of 4-6" OD with several extra pieces on hand for ones that grab or twist. The stuff is easily ripped out of the chuck. That is with a six jaw, a center plug would help but more like an inch or better.

Steve
 
As noted, a 16" long piece of 14" OD PVC pipe with a 1/4" wall (or 1/18" wall) is gonna be like spaghetti. Holding i will be as big a problem as boring it. Maybe bigger.
 
I have a job coming up where I need to bore out a 16" long piece of 14" OD PVC pipe. Finished ID needs to be between 13.5" and 13.75" I have an old 16" swing monarch and I was wondering how to approach this? I am looking at an 18" boring bar from McMaster that takes 1/2" square hss inserts. I can flip the part around and finish from the other side, the tolerance is not tight at all.
Is this a good idea or am I on the wrong track?
Thanks in advance.

With that loose tolerance and paper thin piece, I would look into welding up a reamer.
Cobble up some "wings" and 2 opposed HSS bits.

Get fancy and put some 6300 series ball bearings for the rub blocks.
 
Maybe not this particular job but another way to "look at it" would be 2 or 3 short pieces and solvent weld them together in a fixture. :-)
...lewie...
 
Clamp it to the saddle and run a boring bar between centers. I'd make wooden clamps for the outside that support 360° and help keep it round.
 
Maybe not this particular job but another way to "look at it" would be 2 or 3 short pieces and solvent weld them together in a fixture. :-)
...lewie...

Thought: (hey, I have them on occasion)..

since this thing is coming down to about zero wall thickness. (.125 to .25"). Would it
be easier to just get a sheet of maybe 3/16, and roll it?

I can't imagine boring that thing out to be anything but a giant cluster F*..

You'd need to hold it 360 degrees, and pretty much full length. FCiron has a good idea,
I think that would work with the least amount of fuss, and the highest chance of success.

As for asking about the boring bar. I wouldn't waste a nickel on it. Just for fun many years
ago, I made a cutting tool out of some 2024 aluminum just to see if it worked, it did. A simple
piece of HSS clamped or brazed onto just about any piece of scrap you have kicking around the shop
would work fantastic.

--------------
Thin wall plastic SUCKS!!!! I got suckered into modifying some teflon rings the other day.
They weren't 14" and they weren't a foot long, but they still sucked, taking them down to a
.040 wall thickness with .008" tolerance on the ID. Hold it in my hand for 45 seconds and the
no-go would go. Put it in the frig for 3 minutes and the go wouldn't go.

PVC is at least decent to deal with. Cuts easy, and its moderately rigid. Not as nice
as Delrin to machine, but its not too far off.
 
I had to thin a piece of 12” x12 “ that was already down in a 200’ well for some reason that was undersized and the pump bowls wouldnt go through it. engineer screwed up. Forgot that pvc pipe is thicker internally than steel i used an 3 wing underreqmer cut to size, with file peices welded on it and a 8 roller stabiliizer right above the cutters then pulled up 1/16” and rotated by hand for however many hours it took we ended up with about 1/4 wall but the camera didnt show any cracking and no sand leakage so it did work. Maybe a pull system would work better for you
 
APT multi-tool. Make a custom pilot. Get or modify a blade for the correct ID. Make an extension for the shank.
Have enough extra length for chucking. Use a plug to support the chucked area. Part off after boring.
 
I have a job coming up where I need to bore out a 16" long piece of 14" OD PVC pipe. Finished ID needs to be between 13.5" and 13.75" I have an old 16" swing monarch and I was wondering how to approach this? I am looking at an 18" boring bar from McMaster that takes 1/2" square hss inserts. I can flip the part around and finish from the other side, the tolerance is not tight at all.
Is this a good idea or am I on the wrong track?
Thanks in advance.

I'm in the camp of "It's harder than you think". As others have noted, this is going to be a very squishy/springy work piece. You absolutely need a plug for the ID to use the chuck effectively. If you have a chuck with 2-pc jaws, consider getting some pie jaws to use for holding the part with almost 100% circumferential grip. The use of a steady rest would be a good thing also, but that is something you'd need to cobble up based on lathe swing and workpiece size. The boring tool itself is going to be the least of your worries. When the boring tool cutting edge engages the work at the end away from the chuck, there is a HUGE moment applied to the end of the pipe, and insufficient clamping will be instantly revealed. It will help if you can face one end of the pipe, then flip it to hold the (allegedly) square end , again with the ID plug. A vacuum cleaner to remove the chip in real time is also going to be needed, so you can see what you're doing.

You could also make a faceplate fixture plate, with a turned boss to center and locate the pipe ID/end, with tapped holes at a correct distance to allow use of screw-down clamps of some sort to hold the free end, clamping against the faceplate.
 
It being squishy and squirmy is the problem right up to the time it blows up on you. At some point, unless fully supported, this thing will grab and shatter.

Might be better boring on a milling machine with the part well supported.
 
reduce the diameter of the thing that's supposed to go inside it and then you don't have to bore anything.
 








 
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