Machining characteristics of plastic pipe

I may be getting a project where it is necessary to machine internal threads in
PVC. An threaded
metal cylinder would screw into a 1" ID piece of plastic pipe. Does anyone have
experience with
machining PVC ?
Bob Swinney
Reply to
Robert Swinney
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One, or 10,000? For one, just go slow enough that you don't melt the stuff - it cuts rather easily. Of course, if you cut away too much as threads and are using tapered pipe threads (especially) it may crack - but pipe threads are easily available as PVC fittings.
For production, special tooling shapes and cooling setups can allow higher processing speeds without getting a melted mass of plastic, but I've never done that. One-off lab projects involving PVC, I've done.
Reply to
Ecnerwal
ads in PVC. =A0An threaded
yone have experience with
PVC machines easily, but the chip is one long string. So single pointing threads is not great as you have to clear the string of PVC away before each cut. If I had a lot to do, I would use a tap. Or if a tap was handy, I would use it for just one.
Thinking out of the box, could you machine grooves on the metal so that it is a barbed fitting and just press the metal into the pipe with no machining of the PVC? A form tool would make the machining of the barbs quick.
=20 Dan
Reply to
dcaster
"Robert Swinney" fired this volley in news:zvednSybXY9gyLDXnZ2dnUVZ snipped-for-privacy@giganews.com:
Bob, we use PVC for "disposable" tools (not really, but one-offs for every new project). It machines like a dream. You can usually thread in one pass, although, as mentioned before, the chip comes out as one long string. DON'T take too fine a cut, though, or it will just "fuzz" on you, like polyethylene tends to do. I think, at a certain scale, that the plastic starts to crawl out from under the bit, instead of being cut.
It's abrasive, and will eat up edges in a hurry, but for some reason, it seems to like HSS better than carbide, in terms of ease of cut and finish.
LLoyd
Reply to
Lloyd E. Sponenburgh
ads in PVC. =A0An threaded
yone have experience with
I'd be more inclined to epoxy an internally threaded metal sleeve into the PVC and thread your cylinder into that. If you're going to be moving the thing back and forth, PVC threads aren't going to wear very well and if you're not, just epoxy your cap on and be done with it. My experience with turning PVC pipe is that it's very messy and I had to get cleaned down with a shop vac before I could set foot in the rest of the house. The stuff tracks, too.
Stan
Reply to
stans4
Thanks to all who replied. I am glad to know the stuff is easily machinable. I'm only going to make 1 or 2. I may make a metal sleeve to receive the shank of the bayonet and epoxy that into the 1" PVC pipe. Earlier I had considered epoxying a metal sleeve around the shank and then threading the sleeve to screw into mating internal threads in the PVC. The idea was to make the bayonet removable, reversing it for storage into the handle. Probably a bad idea. I suspect the PVC / metallic threads would wear quite a lot.
Bob Swinney
in PVC. An threaded
have experience with
I'd be more inclined to epoxy an internally threaded metal sleeve into the PVC and thread your cylinder into that. If you're going to be moving the thing back and forth, PVC threads aren't going to wear very well and if you're not, just epoxy your cap on and be done with it. My experience with turning PVC pipe is that it's very messy and I had to get cleaned down with a shop vac before I could set foot in the rest of the house. The stuff tracks, too.
Stan
Reply to
Robert Swinney
I've found the same. I used more rake than a standard tool, like 15 degrees. The trick for handling swarf is a shop vac right at the cutting tool - suck the long string right in.
Karl
Reply to
Karl Townsend
It cuts well. Use slow feeds to keep the heat down. The swarf makes a big mess.... JR Dweller in the cellar
Robert Sw> I may be getting a project where it is necessary to machine internal threads in PVC. An threaded
have experience with
Reply to
JR North
reads in PVC. =A0An threaded
anyone have experience with
Try grey plastic electrical conduit instead.
jsw
Reply to
Jim Wilkins
I'm only going to
epoxy that into the
and then threading
make the bayonet
suspect the PVC /
in PVC. An threaded
have experience with
Has anybody actually epoxied something to PVC, and tested the strength of the bond? My own experience was that epoxy didn't bond to PVC very strongly.
Cheers,
Bruce (bruceinbangkokatgmaildotcom)
Reply to
Bruce In Bangkok
In article , Jim Wilk> Try grey plastic electrical conduit instead.
Machining-wise, essentially the same. The only real advantage of the electrical stuff is sunlight resistance - I use 1/2" for driveway markers (a snow-country thing) and don't have to replace them every year or two like wood or bamboo ones - plus they are cheaper (3 from a 10 foot stick, at 59-79 cents for a 10 foot stick of 1/2"...)
If gluing metal into PVC, you'd probably want to "tooth" the exterior of your metal part and use PVC cement or the multi-purpose PVC/ABS cement - epoxy is a dubious choice, I'd agree with Bruce. Perhaps melt a bit of the swarf into some of the PVC cement (no heat needed - melting PVC is what PVC cement does best, by solvent means) and work that into the teeth/grooves/knurling (or perhaps threads) on the metal. Heat and hose clamps would also do it.
Reply to
Ecnerwal
I'd agree with Bruce. Epoxy is a very brittle material with a high modulous of elasticity. PVC or ABS are pretty soft, low yield point, and creep readily.
Bruce > >
I'm only going to
and epoxy that into the
shank and then threading
make the bayonet
suspect the PVC /
in PVC. An threaded
have experience with
Reply to
RoyJ
ads in PVC. =A0An threaded
yone have experience with
Bob. I guess I would first try heating the PVC with a heat gun and when slightly plastic, screw your metal cylinder in to the PVC. May need to heat the metal some, also. PVC is very easy to work with when heated.
Paul
Reply to
KD7HB
there are some special epoxies for bonding plastics that work better - Devcon makes one that you get at a homeowner's type store
Reply to
Bill Noble
That's what they do on a corregator, to remove the waste cardboard from each side. The vacuum makes a whole shop vac look like a toy. My dad was a foreman for 'Inland Container' for many years.
Reply to
Michael A. Terrell
Are you sure that it is an "epoxy"? I know about various glues for plastic but my (limited) experiences in using epoxy to bond PVC were not a resounding success. If there is a two part, epoxy, adhesive which successfully will bond PVC to an existing epoxy, composite, structure I'd be really happy to hear about it.
Cheers,
Bruce (bruceinbangkokatgmaildotcom)
Reply to
Bruce In Bangkok
PVC. An threaded
have experience with
here in australia we use inch pipe for reticulation. you can buy glue on fittings that are threaded.
Reply to
Stealth Pilot
PVC. An threaded
have experience with
if you need to do a large number of pieces you could do the job a little creatively. you can get pvc soft enough to deform at steam temperatures. steam the tube and expand slightly using a push in insert. place the threaded rod in position then squeeze back the pvc. it should pick up the threads as you press it back.
never attempted this but upvc can be formed into any shape when warm enough.
Reply to
Stealth Pilot
Some info on warm forming pvc here:
formatting link
David Merrill
Reply to
David Merrill
Good link, thanks.
Reply to
Bob Engelhardt

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