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Philsphixit
bending PVC moldings
Philsphixit

Can PVC moldings be bent to fit a bow front cabinet? The molding is 1.25 x 5/8" the cabinet radious is 20". The cabinet holds an antique marble top bow front corner sink. The marble top sits on the two side edges but there is a noticeable gap in front. The top can't be lowered or the front will sit on the door preventing it from closing fully. I have bent PVC pipe using my torch, you have to be careful or it scorches. Could I do the same with the molding?

HoustonRemodeler
Re: bending PVC moldings
HoustonRemodeler

My local lumber yard carries a few flexible mouldings. Not sure what they are made from. They are brown.

dj1
Re: bending PVC moldings
dj1

Quote: " I have bent PVC pipe using my torch, you have to be careful or it scorches. Could I do the same with the molding?"

I've done PVC bending with heat and it worked for me. Why don't you find out about the molding yourself? just use a small piece as a sample. Let us know the results.

Sombreuil_mongrel
Re: bending PVC moldings
Sombreuil_mongrel

A small-section shape like a base shoe will bend easily to a 4ft diameter. A big crown molding, forget it. Don't burn PVC, supposedly gives of very nasty chlorine gasses.
The flex-trim stuff is some kind of polyester resin, a cousin of bondo. It can be ordered to any specified radius/shape (like an arched window casing) , or you can order the flexible generic kind for lesser degrees of bend.

Philsphixit
Re: bending PVC moldings
Philsphixit
HoustonRemodeler wrote:

My local lumber yard carries a few flexible mouldings. Not sure what they are made from. They are brown.

I haven't ever seen flexible moldings locally. I am an hour from town and only have a choice of Lowes, Home Depot and meeks, since I only need a small amount, shipping would cost more than it would be worth.

Philsphixit
Re: bending PVC moldings
Philsphixit
dj1 wrote:

Quote: " I have bent PVC pipe using my torch, you have to be careful or it scorches. Could I do the same with the molding?"

I've done PVC bending with heat and it worked for me. Why don't you find out about the molding yourself? just use a small piece as a sample. Let us know the results.

That's my plan , just wondered if anyone has done it with molding.

Philsphixit
Re: bending PVC moldings
Philsphixit
Sombreuil_mongrel wrote:

A small-section shape like a base shoe will bend easily to a 4ft diameter. A big crown molding, forget it. Don't burn PVC, supposedly gives of very nasty chlorine gasses.
The flex-trim stuff is some kind of polyester resin, a cousin of bondo. It can be ordered to any specified radius/shape (like an arched window casing) , or you can order the flexible generic kind for lesser degrees of bend.

It's a small Ogee but the diameter is a little smaller than 2 feet and I didn't have a piece that I wanted to sacrifice to try it. Did try a molding made out of that foam stuff, just to see if it would bend that far and it just exploded, we are still finding pieces. No don't want to burn it, not just because of the nasty chemicals it off gasses but it causes PVC to bubble and turn brown, won't have a nice smooth surface for paint, besides my wife is an asthmatic. The trick with using the torch is to run it back and forth quickly just to warm it but not to leave it in one place long enough to have it color. Then check to see if it will bend, have to work fast, it cools pretty quick. Kind of like heating marshmallows without browning them. I have only done this for pipe though, I am concerned about distorting the profile on the molding. I'll have to try it and get back to you.

Sombreuil_mongrel
Re: bending PVC moldings
Sombreuil_mongrel

I would leave it a bit long so you have handles on each end or you'll never get the last few inches to curve; this is assuming the cabinet is free and can be worked around; The final length will only be determinable after it is bent and nailed down. Leave it long and trim after installation.
Casey

Mastercarpentry
Re: bending PVC moldings
Mastercarpentry

Given the radius and molding size it's a definite maybe. I'd try it by starting with a heat gun using an identically-shaped jig as the cabinetry outdoors, progressing to a torch only if necessary. I'd also have enough on hand for 3 attempts, maybe 4. If you can't do it by then it probably won't work. An extra helper with another heat gun might be worthwhile too.

Looking forward to hearing and seeing your results!

Phil

Philsphixit
Re: bending PVC moldings
Philsphixit

Yes, it is possible to bend PVC moldings! Sorry it took me so long but I had a lot of trial and error. This is how I did it.
I tried a torch, it works but you have to be very careful and it doesn't bend smoothly. Where the torch heats it distorts the molding, warps and hardens in spots. A heat gun does a little better but it is still too hot. I see they now have adjustable heat guns, but I have just a 1 setting one.

What I used was my wife's 1500 watt blow dryer set on the highest setting. There isn't a diffuser or anything to focus the heat so it heats a wider area. Takes a few minutes to heat the molding so it bends easily. I tacked it and heated a section, clamped it then heated the next section, clamped it and continued till it was clamped all the way around the curve. Then I let it cool and pin nailed it into place. Worked great! No fumes either. :D

Mastercarpentry
Re: bending PVC moldings
Mastercarpentry

Thanks for the update. I've always used my heat gun on low but it's still tricky to get the heat just right.

I haven't tried it with moldings, but electricians use a 'heat box' to bend large NM conduit. It's essentially just some UV fluorescent tubes in a long box enclosure with rollers so you can heat all sides by turning the conduit. If I had a lot to do I'd build something like that and give it a try but for one-off use the heat gun works well enough.

Phil

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