Hot Knife Tool

[Old Nasty]

Does anyone remember an electric hot knife type device you could use to open up doors, trunks, & cut up bodies for top chops & sectioning? I recall as a kid in the '60's you could get one from Auto World I think. Are these things still available?

[Harry P.]

They didn't cut plastic... they melted it.

Use a razor saw on straight cuts, or scribe the panel lines with the back side of an X-acto blade until the piece you want to open is removed.

[Tom Geiger]

I have one of those old AutoWorld panel cutters that I got back in the day. Pretty much just a cheap soldering iron with an exacto blade in it. Forget the drawing they had of someone perfectly opening a door with one. Like Harry said, it pretty much melted a scale foot pathway through your model! Not good for anything.

[pharoah]

What Harry said. They were terrible for opening doors and things like that.

They were good if you wanted to remove a big chunk of plastic,or they were good for burning your hands.

[crazyjim]

I still have the X-Acto blade welded/brazed to a solder iron fitting that I got from Auto World. Think it's worth anything? I still have 1 or 2 of their catalogs too.

[Deathgoblin]

They were the nearest cousin to a wood burning kit, weren't they?

[Tom Geiger]

They were good if you wanted to remove a big chunk of plastic,or they were good for burning your hands.

and when you were 13 they were good for burning plastic, which was part of our fascination with models back in those days!

[peter31a]

MMMM... Love the smell of burning plastic in the morning......

[Mark]

Not for precision work, that's for sure. I have the X-Acto version, though in the past I made one by sawing a notch into the end of a cheap soldering iron. A machine screw held an #11 X-Acto blade in the slot, through a hole drilled perpendicular to the notch. For straight cuts on sheet plastic, I'll either use a saw or do the "scribe and break" method with a box cutter. But I still use the X-Acto piece once in a while, usually to cut odd-shaped parts from sheet plastic or for rough cuts on radiused wheel openings.

[Daddyfink]

Just use a hot butter knife! LOL!

[Skip]

I actually ordered one of those from Auto World after seeing some of the stuff that Model Car Science and Car Model magazines were doing with them. I am sure there must have been some sort of mixup with the order, the precision panel cutting tool I ordered was somehow substituted for a flameless cutting torch!

I do remember seeing an article where they controlled the excessive heat with a rheostat, which "Good Old Uncle Oscar" neglected to include in my order. (Must have been because they knew I wasn't one of those famous magazine guys!)

[KingSix]

I have to admit, when I first got into modeling when I was a kid, I saw the add for these and knew I had to have one. I mean the add clearly showed how "easily" it sliced thru the plastic.. unfortunately I destroyed a jo-han superbird and pro-stock maverick "testing" it .. I still kick myself

Edited September 22, 2013 by KingSix

[Harry P.]

I have to admit, when I first got into modeling when I was a kid, I saw the add for these and knew I had to have one. I mean the add clearly showed how "easily" it sliced thru the plastic.. unfortunately I destroyed a jo-han superbird and pro-stock maverick "testing" it .. I still kick myself

Now there's an example of immoral selling! Passing off a gizmo that melts plastic as some sort of precision cutting device!

[Tom Geiger]

Okay guys... here we go, by popular demand and the need for hobby education...

Here it is, my Auto World Auto Cutter. I knew where it was stored in the hobby room. It hasn't been used in maybe 30-40 years. I hadn't seen it in a long time, and found it in my father's garage when I sold his house after he died. We didn't figure that Auto World actually manufactured this unit, but I was surprised to see exacto on the silver band with the two screws. The end of it screws on and the blade tightens just like a exacto blade does in a knife handle. Mine is frozen stuck with melted plastic from years ago so we'll leave the blade in it. So let's fire this baby up and see what she'll do.

So I broke the seal on a mint sealed MPC '71 Duster kit for this test... actually don't panic, I grabbed this broken body from the depth of my parts box. It had already been robbed of an A pillar because it was warped. And here's the results of our test. Once heated up, the blade did slice through plastic, leaving a melted path behind it. Hotter seemed to be better because it would cut faster. Whenever it slowed down, it melted a wider path.

And here's a close up of our work. My first pass was the back cut, which came out fair since it was a straight line. Still once cleaned up that would be about a 8 inch door jamb. Not good. Then on the front edge you can see where the knife stuttered on the curve. Not good. There is no way to turn a corner, or start a cut where you don't have an edge to start with. See the bottom line. I'd have to cut that another way unless I just stabbed it until the blade sunk in enough to move forward.

I'm not saying I couldn't get better with some practice, but why? I already know a bunch of techniques for cutting plastic and opening panels that don't involve melting plastic.

So that's our real life adult modeler test of the ancient tool of our youth. We can say that the results are about the same as we remembered. And my model room now smells just like my room did when I was 12.

[Harry P.]

Wow, Tom... that's some precision styrene surgery there!

I think you just proved what a racket that "cutter" was!

[ChrisBcritter]

I learned it was OK for hacking smaller pieces out of larger pieces and flaring axle ends; also learned how to make dings and scrapes in my AMT Modified Stockers; how you shouldn't absentmindedly use your thumb to guide the end of it, and how long it takes a second degree burn to heal.

Edit: After a couple years use, the heating and cooling cycles fatigued the blade mount and it snapped off. The end.

Edited September 23, 2013 by ChrisBcritter

[KingSix]

Now there's an example of immoral selling! Passing off a gizmo that melts plastic as some sort of precision cutting device!

no doubt !

[Old Nasty]

Thank you to everyone for your responses & comments towards my inquiry. The demo was particularly interesting. It's funny how we remember weird stuff from our youth.

[Jim B]

Yes, I remember those. It seemed like a good idea when I bought it back in 1980-whenever, but like mode "kitchen gadgets" it got used once & never again.

[ZTony8]

Ah,the Auto Melter-I mean Cutter.I never did get the hang of using mine.It ended up in a drawer in my model desk where I rediscovered it years later.The blade carrier was fused to it's threads and refused removal so into the round file it went.

[59 Impala]

Just use a hot butter knife! LOL!

That's what I used to do and my Mom yelled at me for doing using one of her knives. She only had to yell once. I did find a well used butter knife and used that from then on. I wanted to buy one of these Auto cutters but I couldn't come up with the money. I always spent the money on more kits instead. :D Thanks for the memories. Dan

[Tom Geiger]

I wanted to buy one of these Auto cutters but I couldn't come up with the money. I always spent the money on more kits instead. :D

My father was in the US Army so I lived in Germany as a kid. My only access to American model kits was Auto World. It took something like 90 days to get a package delivered to me, and I ordered about once a month. So I had my notes of each order I made, seeing I was like 3 orders out most times. Each time I got enough money from my lawn mowing and car washing, I'd place an order for a kit, the needed brush paints (couldn't get sprays shipped to me) and some other goodies like Auto World details, Ulrich men and the like. On one order I bought the Auto Cutter and two packs of Auto World hinges, since I believed I'd be cutting out and hinging doors like a pro! Wasn't to be!

[Brett Barrow]

These things actually have a useful purpose - use them to remove clear parts from the sprues without cracking. Also works well with small, delicate parts that would get crushed and broken when trying to remove them with clippers or Xactos.

I use a hot knife for these jobs all the time, but usually I just hold an Xacto in a torch flame instead of breaking out the hot knife/soldering iron. I have one, but it's buried somewhere deep in the tool box. I wouldn't recommend running out and buying one if you don't already have one.

[62rebel]

I recall seeing the article somewhere that instructed on using a hot knife to open doors, etc... well; FIRST off, they said you needed at LEAST two bodies to start with, cutting "good" panels out of one and using the other by cutting inside the shut lines.... !!!!!

I wanted one horribly, but my Dad vetoed this one item (wisely).... at that age, I regularly sliced divots out of my fingers just using Ex-acto knives.... a red-hot soldering iron with a razor sharp blade on it? naaah.

[Tom Geiger]

I wanted one horribly, but my Dad vetoed this one item (wisely).... at that age, I regularly sliced divots out of my fingers just using Ex-acto knives.... a red-hot soldering iron with a razor sharp blade on it? naaah.

Yea, at 12 or 13 I was too busy burning my fingers on my Vacu-form and Creepy Crawlers hot plate. I wonder how many house fires those started!

Then there was the time my buddy Henry got a Cox airplane as a present. He crashed it making it useless within a half hour so we did what 12 year olds will do. We filled the fuselage with the Cox fuel and lit it. The ensuing fireball cost Henry is eye brows. And we thought that was way cool!