Bending PVC conduit without a hotbox

[oldwino]

I know there are plenty of wise guys (I mean wisdom) here so I gotta try. I"m looking to bend a bunch of 1/2" PVC conduit but don't have a hotbox. Any suggestions as to how to heat without over concentrating and screwing things up?

 

[Cmreschke]

BBQ grill.
Also they make a spring like thing that slides into the conduit to keep it from collapsing, you slide that in and bend it on a hand bender. 3/4 hand bender for 1/2 pvc.
But I'd just do the grill.

 

[LXCam]

That size will bend in the next larger size emt bender if you have one. It ain't pretty and it's not a full 90 cause of spring back but it'll fatigue the pic enough it works. Also any torch will do just fine, but don't burn the pvc.

 

[rkevins]

I watched a man use a fish cooker he would lay the pipe on the rack that holds the cook pot rotate the conduit until limp the lay it out on a plywood form and mist it with water to cool it, some of the best bends I have ever seen. He made all his bends so fewer couplers.

 

[CJ7VFR]

I have used my Heat Gun to soften and bend PVC pipe. I fill the pipe up with sand, temporarily push end caps on the ends of the pipe, heat up the area where I want the bend, and then bend it.

When I am done, I let it cool off, pull the end caps off, and let the sand run out to reuse again.

Jim

 

[oldwino]

Thanx for the quick replies fellas. Really like the BBQ idea. I did catch an "electrician" pouring PVC glue over pipe and lighting it to heat and bend but even I have higher standards than that

 

[Stuart in MN]

I've done it with a Bernzomatic torch, you just have to be careful to keep moving the torch and not getting the conduit too hot.

 

[CNGsaves]

+1 for fill with sand, then heat and bend.

 

[nehog]

Sand fill, and heat gun. Not a steep bend then no sand needed.

 

[Aceman]

I know there are plenty of wise guys (I mean wisdom) here so I gotta try. I"m looking to bend a bunch of 1/2" PVC conduit but don't have a hotbox. Any suggestions as to how to heat without over concentrating and screwing things up?

1/2" pvc is very flexible. If this is going in the dirt, you should not need to heat it at all, just bow it. If this is above ground, offsets and such, on the wall or ceiling where you can see it, if you look hard enough you can buy factory box offsets, etc.

Where exactly are these bends going?

Our shop does not use 1/2" pvc. The conduit fill is horrible, it usually makes more sense to run 3/4".

 

[Richard Cranium]

and is this thin wall or schedule 40

 

[toyotadriver]

I've bent up to 2 1/2 inch with nothing but a Harbor Freight electric heat gun. Worked fine. Keep the heat moving until it softens. Bend carefully and it goes fine.

 

[alfredeneuman]

Smaller sizes of PVC can be heated by inserting the conduit into the tailpipe of a running car or truck.

 

[wyliesdiesels]

Torch or heat gun!

 

[ND80]

Tape up the ends with duct tape then use a weed burner or a torch with a wide tip.

 

[The Cobbler]

Smaller sizes of PVC can be heated by inserting the conduit into the tailpipe of a running car or truck.

This. An old electrician friend had a garage exhaust hose he would take to the job. place the conduit in it & run the van. voila!!

 

[gearheads78]

Heat gun worked great for me.

 

[oldwino]

1/2" pvc is very flexible. If this is going in the dirt, you should not need to heat it at all, just bow it. If this is above ground, offsets and such, on the wall or ceiling where you can see it, if you look hard enough you can buy factory box offsets, etc.

Where exactly are these bends going?

Our shop does not use 1/2" pvc. The conduit fill is horrible, it usually makes more sense to run 3/4".

ACEMAN
most of conduit will be direct buried but there are a couple of significant grade-breaks that would require a ton more digging (hand). Other sections are too be suspended under a deck but will require a couple of oddball bends (around 70 and around 130 degree) with an offset or two.

I agree with using 3/4" most of the time but these are minimum fill (one run is a sprinkler control wire and the other is LV lighting.

thanks to all for your responses and I will report in tomorrow evening on how it went.

 

[zmaxmotorsports]

An electric stove works great for me,I prefer it over gas so it doesnt burn as easy.
Just make sure to keep spinning the pipe as you heat it.

 

[rharman]

Heat gun has always worked fine for me.

What about some of that flexible PVC stuff they sell? Not sure how easy to pull through but you're doing very light wire anyway.

 

[yyc_ranger_4x4]

Inspectors don't like seeing burn marks. Most of our first year apprentices burn their share of pipe. LOL

That being said...not much works faster than a tiger torch if you know what you're doing. I've bent any rigid pvc from 1/2" through 6". Works great when its cold out or when you have to offset something that's already installed in the ground. Keep the torch moving and keep a close eye for spots turning yellow....it will burn very quickly.

 

[checkthisout]

As suggested above, Home Depot or whatever sells spring kits that you can use to help maintain the diameter of the pipe at the bend. It makes it easier to do nicer looking work especially if you have a lot to bend.

As others have said, heat gun, weed burner (that's a lot of heat), a propane torch, an oven, a BBQ....you get the idea. Whatever gets hot and allows you to get heat on the pipe.

Dedicate one piece as sacrificial for practice!

 

[bjcouche]

If you have never done this before, I would suggest the heat gun instead of any type of torch. Keep the gun moving and try to heat the conduit all the way around. Also heat the area that you want the bend at plus a few inches on either end of the bend. 1/2" should be fairly easy. With a heat gun, it will take longer to heat up, so be patient, but it's less likely to bun than using a torch. Remember, it takes a while for the interior to get hot, even though the outside is hot, plastic doesn't transfer heat like steel. I've bent a lot of 1/2 to 2" with a heat gun. IF I can I lay the conduit on a sheet of plywood and roll the conduit as i move the heat gun back and forth to heat it evenly. Eventually the conduit will get real wimpy and bend easily. If it wants to kink, then it's not hot enough yet. I've never had to use sand. The theory behind the sand is that it holds the inside shape and helps prevent kinking. I've rarely had to bend a radius that was sharper than a factory radius, so maybe that's when sand is needed.
Another tip, once it's up to temperature, hold the conduit in the bent position either by hand or with a form until completely cool. Remember the outside will feel cool way before the inside is. I usually use a compressed air gun and blow air through the conduit to cool it quicker from the inside. I then set it aside to fully cool to room temp before using it. I'm not an electrician, but I am a perfectionist.....

Brian

 

[LS6 Tommy]

I have used my Heat Gun to soften and bend PVC pipe. I fill the pipe up with sand, temporarily push end caps on the ends of the pipe, heat up the area where I want the bend, and then bend it.

When I am done, I let it cool off, pull the end caps off, and let the sand run out to reuse again.

Jim

This is what I've seen done without a hotbox.

Tommy

 

[zmaxmotorsports]

This is what I've seen done without a hotbox.

Tommy

Id be worried about sand sticking to the inside of the pvc,As long as you heat a longer area then needed and work fast its usually not a problem.
Having a wet rag handy to cool the pipe as you smooth out the bend youll be ok.
If youre bending a bunch of 90's having a pre bent 90 for a pattern helps get the radius of the bend right.

 

[Zeke]

I watched a man use a fish cooker he would lay the pipe on the rack that holds the cook pot rotate the conduit until limp the lay it out on a plywood form and mist it with water to cool it, some of the best bends I have ever seen. He made all his bends so fewer couplers.

I've seen the same process with a little bit of air pressure in the pipe to keep it round. I've seen up to " done this way.

 

[nh_yota]

Use a heat gun and something like a spring or sand to keep it from kinking when you bend it. Make sure you heat it up evenly along where you're going to bend it because if it's only warm in one spot it will kink in that spot when you bend it.

 

[CJ7VFR]

Id be worried about sand sticking to the inside of the pvc...

As long as you don't get the PVC so hot it starts to melt the plastic on the inisde, the sand won't stick to it.

And if you are getting the PVC hot enough to get the inside to start to melt, the outside will have long been destroyed by completely melting and wrecking the pipe.

Also, the sand acts as a bit of a heatsink, so as you heat the pipe the sand transfers some of the heat to a larger area inside the pipe.

In all the years I have been bending PVC I have never had the sand stick to the inside other than what some static cling will make stick as I empty out the pipes.

And running some water thru the pipe with a hose takes care of that.

No matter which way you end up using a heat source to bend PVC pipe, the real trick is to practice, practice, practice!

You will actually get a "feel" for it as you learn. You will "know" when it is hot enough, pliable enough, and just right to bend it.

It is amazing what kind of shapes you can create! I bent a piece one time that had several different bends in different directions so it would snake around some roof and floor joists in my garage attic to help protect some wires I was running to a light.

Did I have to spend all that time doing that? No. Was it fun? Yes. Did I drink lots of beer when it was done? Hell yes!

Jim

 

[zmaxmotorsports]

As long as you don't get the PVC so hot it starts to melt the plastic on the inisde, the sand won't stick to it.

And if you are getting the PVC hot enough to get the inside to start to melt, the outside will have long been destroyed by completely melting and wrecking the pipe.

Also, the sand acts as a bit of a heatsink, so as you heat the pipe the sand transfers some of the heat to a larger area inside the pipe.

In all the years I have been bending PVC I have never had the sand stick to the inside other than what some static cling will make stick as I empty out the pipes.

And running some water thru the pipe with a hose takes care of that.

No matter which way you end up using a heat source to bend PVC pipe, the real trick is to practice, practice, practice!

You will actually get a "feel" for it as you learn. You will "know" when it is hot enough, pliable enough, and just right to bend it.

Jim

Ive been bending pvc for many years,never had a need to fill it with sand anyway.

 

[CJ7VFR]

Ive been bending pvc for many years,never had a need to fill it with sand anyway.

Because you "learned" the way the pipe felt when it was ready to bend!!

I could probably do that now too, but I have all the sand, end caps and stuff, so I just keep doing it that way.

Jim

 

[zmaxmotorsports]

Because you "learned" the way the pipe felt when it was ready to bend!!

I could probably do that now too, but I have all the sand, end caps and stuff, so I just keep doing it that way.

Jim

Back when I started out in the trades we didnt have apprentice labor laws,The journeyman were allowed to beat us rigorously with what ever object they could lay their hands on!
You learned to either do things right and fast or you got to be good at dodging hammers/ conduit benders/pipe wrenches/soil pipe snappers............!
Once I learned to start throwing things back at them my life got easier.
Ah the 70s.

 

[oldwino]

Thanx for all your help, guys.
As I am inclined to do I!ll ask for advice, take a simple job and make it complicated. I ended up making my own box using an 18" piece of 1 1/2" steel pipe clamped in the vice vertically. I supported PVC with a clamp and heated steel pipe with a torch. Took a couple of tries to get heat right but it worked like a champ. Even heat all around and not messing with turning pipe

 

[zmaxmotorsports]

Thanx for all your help, guys.
As I am inclined to do I!ll ask for advice, take a simple job and make it complicated. I ended up making my own box using an 18" piece of 1 1/2" steel pipe clamped in the vice vertically. I supported PVC with a clamp and heated steel pipe with a torch. Took a couple of tries to get heat right but it worked like a champ. Even heat all around and not messing with turning pipe

Pictures?

 

[jdieter]

Pictures?

made a similar contraption out of a 3' piece of round furnace duct with a short 2x4 cut to fit part of the radius on each end with a couple rollers fixed to each 2x4 to support conduit and a couple holes cut in the side of the round duct for heat gun nozzles. Bent up to 4" with no problem. Also used the tailpipe trick years ago in my electrician days, boss was to cheap to buy a proper heat box.

 

[LS6 Tommy]

I forgot to mention there are relativiely low cost "blanket" type heaters for bending PVC. They're still not what I would call "cheap", but they're usually about 1/2 the cost of a hot box for the same size range of PVC. The previously mentioned internal spring benders are even cheaper, but I've never seen one used.

Tommy

 

[Big Daddy Chop Shop]

Probably stating the obvious here, but I would shy away from open flame and PVC. If you happen to screw up (and it you have never done this before, you will) and get it too hot, you will get Chlorine gas. I will spare you the details, but it is beyond nasty stuff.

Heat gun or such is the safer bet.