Problem with PVC?

[Dave Norbury]

I've seen a number of warnings about lasering materials that contain PVC. I'm curious, is the problem that the gasses somehow mess up the laser or that they are poisonous to the operator (or both)?

Are there other materials that we should avoid?

Thanks,

Dave

[Scott Shepherd]

Gases created will rust the inside of the laser. There used to be a photo of a machine that ran PVC on here, but I've looked several times and can't locate it. Think of a 1970 era car, living in town near the ocean :) That's what it looked like inside the laser.

[greg lindsey]

I have a friend ( lets call him my Guru of engraving) taught me tons about corel and engraving. He regulary cuts Harco blasting material, I mean lots of the stuff with 2- 36EXT 120 watt machines, he has a process of cutting the film for sandblasting plaques, his machines looks as good today as two years ago, so I am on the fence here about cutting PVC. I myself have cut much on it also, without ever having a single problem, I know the risks of the vapors and have excellent ventalation, my machines show no abnormal wear from this cutting, maybe we are just getting lucky.

[Dan Hintz]

Vectoring a film and cutting a 1" thick piece are drastically different in the amount of gases released... it also helps if you have a really strong vacuum system.

[Richard Rumancik]

Dave, the other "common" material you should avoid are Teflon-based materials. All materials generate gases you should not breathe but PVC and Teflon are often identified as to be avoided.

Some people on this forum cut sign vinyl routinely, but there is much more risk in cutting thicker materials. Film and 3-mil vinyl is one thing but personally I would not recommend cutting sheet materials. Greg says he does not see any issues with cutting sand blast masking but it probably is quite thin.

The success can greatly depend on the exhaust system, in terms of flow as well as the direction it takes when it exhausts from the laser chamber. If the exhaust from PVC settles on metallic parts (like the rails) then hydrochloric acid can condense out on the surfaces. So if someone wants to cut PVC (even films) it would be a good idea to clean all surfaces in the exhaust path after the job is complete or corrosion can result. You need to be careful about opening the lid and breathing residual fumes.

Generally the warranty on mechanical parts will be voided if the manufacturer sees evidence of corrosion due to acid residues. Also, if you get any hydrochloric acid condensing on your lenses they will probably be damaged.

[greg lindsey]

Richard and Dan are both correct, I would never cut any real thickness of PVC on my machines, I mailnly use my summits for cutting the masks because they are older machines and the vacumme gantry travels along with the arm, so the point of vacumme is directly behind the cutting beam, unlike my 32ex which is stationary. I also use a big overkill on the vacumme, way more than i need.

[Dan Hintz]

A second note I don't believe I've ever seen mentioned on the board yet, how to reduce (eliminate?) corrosion issues with chlorinated compounds...

The chlorinated compounds (of various sorts) leaving the machine aren't the enemy themselves, it's when they combine with moisture in the air to create the dreaded HCl molecule (H20 molecules gladly give up a hydrogen to chlorine molecules)... you can reduce the amount of HCl by reducing the amount of moisture in the air, i.e., use your air conditioner or dehumidifier. Dry air will allow the chlorinated compounds to pass through your system without attaching itself and be absorbed by your air scrubber (assuming you have one).

[Joe Pelonio]

I have cut and engraved sandblast resist too, but it was rubber, not vinyl. Actually works as a rubber stamp material.

As for PVC, the machine I saw that taught me a lesson was used to cut
about 50 pieces of 3mm PVC sheet (Sintra). It looked like it had been at the bottom of the sea for weeks, rust and corrosion all over inside. Regardless of how good your exhaust works, the fumes going out the vent are toxic and you are likely to have birds dropping out of the tree outside or worse neighbors getting sick. Just not worth the risk.

[Bill Cunningham]

Gas from burnt Teflon in particular kills birds stone dead... Burn a pan on the stove, and your pet bird becomes the Monty Python parrot..

[Joe Pelonio]

Funny, two mentions of dead birds, then my wife and I are sitting watching baseball on TV and a stupid starling runs into the window.:eek:

[Zvi Grinberg]

For those who want to see what's the problem with PVC

This is an X-Motor of a ULS machine that was used (so I have been told) for 3 months with PVC.

http://i94.photobucket.com/albums/l98/ZviGr/pvc-1.jpg

Do you want to see how X-Motors look after several years of not using PVC? I believe I can bring many pictures

[Dan Hintz]

Birds and baseball don't mix:
http://www.youtube.com/watch?v=AMQbC8oMF00

[Frank Corker]

For those who want to see what's the problem with PVC

This is an X-Motor of a ULS machine that was used (so I have been told) for 3 months with PVC.


Do you want to see how X-Motors look after several years of not using PVC? I believe I can bring many pictures

Yes me. I would like to see more pictures if you have them please post.

[Dan Hintz]

Great, now I don't know who's being more facetious, Frank or Viktor ;)

[John Frazee]

Just a thought...... if lasering pvc and teflon kills birds, what can I laser to kill all these darn stray cats?:D

As for the photo's I would like to see that same motor before/without cutting pvc. If it does this much damage to parts, I wonder what some of our lungs look like?

[Mark Ross]

Not to mention that lasering white pvc yellows it and with pvc when we have tried to laser it, it just melts, can't get a nice edge to it.

[Joe De Medeiros]

Just a thought...... if lasering pvc and teflon kills birds, what can I laser to kill all these darn stray cats?:D


My shop is an old coach house (1849), and I'm constantly chasing stray cats, raccoons and squirrels out. At present there's a persistent raccoon, that's taken refuge in my shop, and leaving little foot prints on everything.

[Dave Norbury]

Thanks for all the replies. This is obviously important stuff to know!

[Bill Cunningham]

Hey ! I just had a partridge at my back door.. Just one, not the whole family :D It's been a long time since I've seen a partridge around here..

[Bill Cunningham]

My shop is an old coach house (1849), and I'm constantly chasing stray cats, raccoons and squirrels out. At present there's a persistent raccoon, that's taken refuge in my shop, and leaving little foot prints on everything.

Raccoons can do a lot of damage, and their crap is dangerously toxic. If it's inside your shop, a gunshot won't be heard and won't freak your neighbors, the best cure is an evenings well placed .22, a plastic bag, and a trip to a country lane where some coyote will probably enjoy it!

[Dan Hintz]

Hey ! I just had a partridge at my back door.. Just one, not the whole family :D It's been a long time since I've seen a partridge around here..
Any pear trees?

[Dave Johnson29]

For those who want to see what's the problem with PVC

The question is, did they have an efficient extraction system. I regularly cut Schedule-40 PVC pipe and do not have a spot of rust inside the machine.

One of the substances given off joins with the moisture in the air to form Hydrochloric acid and this will cause rust if let settle on steel parts.

However when I am cutting PVC I have the extractor at full speed and not even the steel blades of the extractor impeller show signs of rusting.

Probably not good to be breathing the gasses coming off but they are outside and moving fast. The exhaust ducting is all PVC pipe.

[Bill Cunningham]

Any pear trees?
Nope, and no maids a milkin either :mad: