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I have a large door frame that I want to break into smaller pieces so I can fit it into my car and take it to the dump. The frame is PVC, but has steel on the inside.

I've been trying to avoid an angle grinder because of everything I've been reading online regarding the risks associated with it, so I tried a hacksaw, but it seems to be doing nothing to the steel.

I've seen a few warnings against using an angle grinder on wood (including this question). I really only need it for the steel/metal parts, but they are all surrounded by PVC and even some wood, and I don't think I can really separate them, so I'd have to cut through everything?

Would it be a really bad idea to get a blade for cutting metal and trying to cut through everything?

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    If an angle-grinder was the tool I had on hand, I would not hesitate to tear up that stuff with it. Is it the "best" tool for that? Well, "best" is subjective and to me the "best" is what I have right now that I know will work and I am comfortable using safely. You don't need to worry about incidental wood or plastic, which may load/gum up the wheel but who cares, they are a couple bucks apiece... – Jimmy Fix-it Oct 9 '20 at 0:04
  • There seems to be an agreement that it will work but might not be the best tool for the job; a reciprocating saw might be ineffective because of the difficulty holding the internal structure in place. I've certainly seen people use an angle grinder to cut Perspex etc. to approximate size, I don't know whether it would be beneficial/safe to cut the PVC wet. – Mark Morgan Lloyd Oct 9 '20 at 9:24
  • Can you fit the frame on your car instead? – Crowley Oct 9 '20 at 11:09
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    The risks of using angle grinders with carving tools on wood seem to be much higher than using the tool to cut or grind metal. They are really quite different operations despite using the same base tool. – StayOnTarget Oct 9 '20 at 14:23
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    Why wreck it? List the item on your local auction site for $1, pickup only. The winner will transport it away for you. There are even services like freecycle.org which put you in contact with people who will take and reuse your item. – Criggie Oct 9 '20 at 21:40
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Using an angle grinder you're going to end up with melted PVC clogging the blade, and possible fire from hot metal/sparks that you are grinding igniting the plastic, etc.

As such, the suggestion to use a reciprocating saw (effectively a form of power hacksaw) is valid - however, since you already own a hacksaw, and it does not seem like it should be such a huge job, I would suggest that possibly your hacksaw blade might be dull, if it's "doing nothing to the steel" and that a new, sharp, hacksaw blade might be a very different experience. Hacksaws are made to cut steel, but a dull blade won't cut much of anything. Hacksaw blades are replaceable precisely so that you can have a sharp one easily (they are not generally considered to be practical to sharpen.)

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    Hacksaw needs the teeth to be sharpen. You're not going to sharpen it in any meaningful way manually. You might as well beg for money on the street and buy a new blade because it'll take less work and you'll get it done faster. – Nelson Oct 9 '20 at 14:23
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    But do be sure to get blades actually meant for steel. For a full-size hacksaw they're harder and a little more expensive than those for softer metals but worth it. If you've only got a junior hacksaw the common blades are rubbish on steel and hard ones aren't always easy to find – Chris H Oct 9 '20 at 14:25
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I think you'd do better with a Sawzall. That's the trade name - like Kleenex, everyone uses the name no matter what the brand. Just looked up - it is generically a reciprocating saw. These things can be dangerous beasts, but I think they'd be a lot safer for this type of job than an angle grinder. Buy/beg/borrow/rent - for one small job, any of the options will work. Just make sure you have a blade designed for cutting metal (very hard material, closely spaced teeth) and not wood (wide teeth). Corded or cordless.

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    I agree with using a reciprocating saw as well. Not only is it safer, but it's also useful to cut thru any hardware (nails or otherwise) that are holding the door frame to the studs. – nnamerz Oct 8 '20 at 23:35
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    I think the OP may be in the U.K., in which case it’s rare to call it a Sawzall! – Tim Oct 9 '20 at 7:59
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    inexpensive screwfix.com/p/… – spikey_richie Oct 9 '20 at 10:21
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Yes, it'll be fine but heed the valid warnings given in the other answers about the minor risk of melting plastic and starting small fires. You won't instantly be sitting in the middle of a blazing inferno; it'd me more like having a few birthday candles in front of you, but the fumes are unpleasant.. The biggest risk from an angle grinder in this context is probably from the tool itself

To reduce the amount of melted plastic, don't hold the grider in the same place; go back and forth across the plastic so you aren't overheating any one part causing it to melt. Have a damp cloth or water sprayer on hand to smother anything that ignites. PVC frames that are reinforced have metal box section inside that is a snug fit, so you're unlikely to start a fire inside the frame/any flames you see will be surface only. Additionally, you seem to have already removed the frame from the building so cutting it up in the yard is considerably safer than generating a sparkshow with it still attached to your house, and if you can arrange for good ventilation and a mask to avoid inhaling fine particles it will help.

If you're not into all this doom-talk of fires and would prefer to avoid the possibility you'll probably have good success in using the hacksaw to cut along the plastic weld lines. In my experience the fabrication of PVC units is that long straight sections of profile, including a metal box section, are cut to length and then only the plastic is welded; the metal isn't welded/doesn't continue around the corner. The metal just provides bending resistance for the mid section. If you do find metal in the corners, you may also have success in cutting the plastic all the way round in some part of the mod section, then smacking the frame apart with a hammer - the box section isn't fixed to the plastic (except for where you've screwed frame fixing through it) so they should separate with some determination

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  • This is the best answer because it addresses the question of the angle grinder, which is certainly an effective tool for the job. I often use it for plain PVC as well as for steel. Also, the warning to be careful is good. The heat will at least make the pvc smoke--unpleasant but not deadly for this short exposure. Do wear safety glasses--the cutting discs will still throw sparks from the steel. – Conrado Oct 9 '20 at 20:57
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    @Conrado I'd say PVC smoke is a bit beyond unpleasant. It is indeed not deadly in small amounts, but it can still have potentially nasty long-term effects on your respiratory tract if you inhale it. Not discounting use of an angle grinder here, just make sure it's in a well ventilated area and avoid inhaling any smoke/fumes. – Austin Hemmelgarn Oct 9 '20 at 22:46
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    And as noted in the answer; use it to grind the plastic (by not holding the grinder in the same place all the time) rather than toast it. I forgot to point out it'd be worth wearing a respiratory mask; inhaling fine plastic particles isn't ideal! – Caius Jard Oct 9 '20 at 22:49
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    @austin Right-I should have said toxic but not deadly. By all means, avoid it like the plague. If you can cut downwind from yourself, you shouldn't really even have to breath it in at all. – Conrado Oct 10 '20 at 0:29
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As the goal is just to make it smaller:

I'd use a sledge hammer to fold it up until it fits in the car, or if there's room just store it (even outdoors) until the next council hard waste collection.

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    Concur - its going to the trash so condition is not relevant. It may be possible to support the ends and stomp/hit the unsupported middle until it folds. – Criggie Oct 9 '20 at 21:37
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    @Criggie Do not stomp - it can break/collapse unwanted way and you will be all inside the mess. Eye/hand protection plus hammering is much better. I would also recommed old forged two-hand axe. I was able to cut two cars in pieces with one axe from begining of 20th centure.. – Crowley Oct 10 '20 at 21:59
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FWIW, I had a similar problem with some steel re-enforced concrete. I used a stone blade to cut away a load of the concrete, exposing a reasonably large amount of the steel, then switched to a metal blade to cut the steel. I did try a (new) hacksaw, but found it tedious, and seemed to dull the blade very quickly whilst doing relatively little to the steel.

In this case, I'd say use the hacksaw to cut away a chunk of the plastic/wood and then grind through the steel - but take suitable precautions to avoid sparks on the plastic or plastic on the grinder. Avoiding heat is probably the best advice, so moving the grinder about so that you're grinding different bits of metal at a time, and maybe just go at it for a couple of minutes, then leave it for 10 minutes before you go back and do a bit more.

Another answer recommends a sledge hammer. You may find that when stripped of the plastic and wood, the steel buckles and bends more easily than you might imagine (when suitably persuaded by a hammer). The problem is that's a one-way trip. If you start doing it that way, you're going to have to finish. At least with the grinder you could change your mind and switch to a different method.

The last thing I'll just add is that our family car has some Tardis-like qualities when it really needs to (ie. when I've bought a load of materials without thinking about how I'm going to get them home). You may find you can fit more in your car than you imagine if you try hard enough, so may need a lot less cutting than it may appear.

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A circular saw with a common carbide-tipped blade will make quick work of it. The steel in such frames is soft and will dull your blade only slightly, if at all.

Otherwise, just knock it apart at the corners and slide it into the car. I carry 8' lumber in my little sedan all the time.

Use eye and ear protection.

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  • Some cars have a surprising storage length, if you fold down the front seat, and any rear seats that can move. – Criggie Oct 9 '20 at 21:38

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