# cutting a hole in plastic



## raleets (Jan 2, 2011)

Another newbie question comin' at ya'....
I'm now ready to install lights inside my buildings. I've assembled most of them from kits and they all have openings in the base so that I can install an LED inside easily. However, I also bought a few older buildings on eBay that have a solid base with no opening. Therefore, I need to create an access hole. What's a fast, simple way to cut the plastic without making a mess of the building?
Thanks in advance for your advice.
Bob


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## tankist (Jun 11, 2009)

drill, baby, drill! 

for least strain on assembled model you might want to do it in several passes , using small drill bit first and going up.


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## gunrunnerjohn (Nov 10, 2010)

You also want to back the plastic if possible, that prevents the break-through that sometimes cracks things.


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## TapRoot (Oct 3, 2010)

gunrunnerjohn said:


> You also want to back the plastic if possible, that prevents the break-through that sometimes cracks things.


with tape......


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## gunrunnerjohn (Nov 10, 2010)

I stick some tape on it, and also drill with a wooden block backing it. This prevents the plastic from flexing and possibly cracking. I also drill slowly.


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## concretepumper (Jan 2, 2011)

Drill slow with a sharp bit is "key"! Go for it. CA glue will fix any mess up.


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## cabledawg (Nov 30, 2010)

If its a preassembled building a backing block may not be possible. Tankist and CP have got it, start with a small bit and work your way up. Be sure to have sharp bits and while you want go slow, dont go so slow that the bit digs in instead of cutting.


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## gunrunnerjohn (Nov 10, 2010)

You can also finish a hole with jeweler's files instead of trying to drill it larger, safer.


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## raleets (Jan 2, 2011)

Thanks, guys,
Yep, I had figured that would be the drill :laugh:......If you guys didn't come up with anything "magic", I had planned to use my small cordless drill with some sharp bits working up in size until I could use my teenie little hole saw to finish the task.
My cordless can be speed controlled, so I don't go burserk into the plastic.
Can't back the bugger 'cause they're already built and sealed.
Good idea using tape. This can (hopefully) add some stability and prevent a crack.
I need to make an opening large enough to at least use tweezers to place an LED up near the ceiling and fix it in place with Gorilla tape. That stuff is stickier than duct tape, if you can believe that!
Never had so much fun getting frustrated in my life! 
Bob


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## gunrunnerjohn (Nov 10, 2010)

Shouldn't have glued them together before lighting them!


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## raleets (Jan 2, 2011)

Gunrunnerjohn,
As stated in my opening remarks, I bought some used buildings on eBay that were already assembled and GLUED.
Therefore, I'm now needing an access hole to light those suckers up.
But, many thanks, 'cause you're so right in that they should have been lighted first.
I'll slay this dragon with my trusty drill and tweezers 
Thanks again,
Bob


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## NIMT (Jan 6, 2011)

If it's not going to show I use a soldering iron tip to bore a hole. No cracking going on with that. If it's in an almost completely inaccessible lo-cal I heat up a cloths hanger wire to bore the hole.
CA jell works great for stuff like that, a dab on the bottom if the light then up in the hole to the ceiling and touch done.


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## gunrunnerjohn (Nov 10, 2010)

raleets said:


> Gunrunnerjohn,
> As stated in my opening remarks, I bought some used buildings on eBay that were already assembled and GLUED.


Just having some fun with you, I realized what the situation was.


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## raleets (Jan 2, 2011)

gunrunnerjohn,
Yeh, I know you're just funnin' me..
And that hot soldering iron idea was also in mind but the stench of the melting plastic is a bit much, right? Respirator, here I come!
Within the next few days there WILL be some access for lighting in those little puppies.
Franks a rot,
Bob


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## gunrunnerjohn (Nov 10, 2010)

I love the smell of burning plastic in the morning, unless I didn't want a hole there! 

Note that you should consider the heat of the bulb in it's placement, I've seen lots of plastic buildings with melt marks from too hot a bulb too close to the plastic.


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## raleets (Jan 2, 2011)

Which is precisely why I'm going with LED's! :thumbsup:


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## gunrunnerjohn (Nov 10, 2010)

Good plan.


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## SkyArcher (Oct 20, 2010)

Stop!! Don't use a twist drill to drill holes in plastic. I use a Uni-bit aka step drill to drill holes in sheet plastic. The $12.99 bits from Harbor Freight works great!! No digging or tearing and it is not messy like boring hole with a soldering iron. See:

http://www.harborfreight.com/3-piece-titanium-nitride-coated-high-speed-steel-step-drills-91616.html


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## T-Man (May 16, 2008)

They sell small forstner bits I have a set from Big Lots. They act like a hole saw and would well on plastic. I never thought of it until now.

Bits


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## gunrunnerjohn (Nov 10, 2010)

I have a set of Forstner bits, but nothing really small. They go up to 2 1/2", but the smallest is 1/4". A Forstner bit needs a pilot hole, so you still have to drill a hole.


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## gunrunnerjohn (Nov 10, 2010)

SkyArcher said:


> Stop!! Don't use a twist drill to drill holes in plastic. I use a Uni-bit aka step drill to drill holes in sheet plastic. The $12.99 bits from Harbor Freight works great!! No digging or tearing and it is not messy like boring hole with a soldering iron. See:
> 
> http://www.harborfreight.com/3-piece-titanium-nitride-coated-high-speed-steel-step-drills-91616.html


Never tried one of these, they always looked a bit cheesy to me. I may have to take another look, I have a Harbor Freight down the street that I stop at from time to time.


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## raleets (Jan 2, 2011)

Guys,
The dragon has been slain! Once in awhile I get a brainstorm. This one actually worked :laugh:
I put a sharp 1/8" bit in my drill press, turned the model building upside down, marked the desired hole area with a black marking pen, and went at it.
VOILA! By carefully and slowly tracing the black line I was able to "cut" out my opening in a jiffy. 
Yeah, it made a mess with teenie plastic shavings all over the place, including me, but the vacuum took care of that problem. A little trimming on the edges with my Exacto knife finished the job.
Once in a blue moon something works out the way it's supposed to work out!
On to installing LED's this weekend. 
Thanks for all your input!!! :thumbsup:
Bob


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## gunrunnerjohn (Nov 10, 2010)

I love it when a plan comes together.


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## T-Man (May 16, 2008)

gunrunnerjohn said:


> I have a set of Forstner bits, but nothing really small. They go up to 2 1/2", but the smallest is 1/4". A Forstner bit needs a pilot hole, so you still have to drill a hole.


Then the hole is big enough to pull the light out and move the building.:thumbsup:


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## gunrunnerjohn (Nov 10, 2010)

If the building is smaller than 2 1/2", you have a whole different issue. 

FWIW, I just drilled one of my Amtrak passenger cars for a pair of trailing red indicator lights. No sweat, I drilled with the small drill, then moved up. For the final fitting of the LED's, I actually hand drilled with the largest bit so I didn't overshoot the depth I wanted. The car was low class, just had a couple of flat spots where the lights should be.


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## SkyArcher (Oct 20, 2010)

Here is another trick to drilling plastic. If you have to drill a lot of holes in plastic especially in acrylic, there are special drill bits that are designed for drilling acrylic. I usually just regrind an old twist drill bit to have a 88 deg cutting edge instead of the standard 30 degs cutting edge.


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## raleets (Jan 2, 2011)

I guess the best part about drilling/cutting into the bottom of a plastic model building is that it's strictly for utility purposes and not for "show". Once the light is installed and the building is set in place there's no way to tell that little bugger was ever altered. 
I won't tell if you don't! 
Bob


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