Best technique for drilling clean holes into styrene?

[No_6]

I've been having the problem of the melted plastic spinning itself around the drill bit as I drill, thus causing the hole to be larger than I wanted it to be. I've been using my dremel... is that the problem? Do I need to go to a hand tool?

[Kylwell]

Slower speeds and sharp bits are the only help.

Part of the reason I love the cordless 10.8v Dremel, really slow speeds.

A hand drill will also solve the problem.

[USS Atlantis]

Slower speeds and sharp bits are the only help.

Part of the reason I love the cordless 10.8v Dremel, really slow speeds.

A hand drill will also solve the problem.

I know it's a pain, but the best way is with a Pin-Vise by hand

If you have to use the Dremel - get a variable speed controller for it and use the SLOWEST speed possible

Also I use Titanium-Nitride coated bits - they run cooler than the standard HSS or Cobalt coated ones

[srspicer]

Yup, what they said. Slower speed is the key. Also, use a pointed tool to start a small dimple for the bit to guide into.

Scott

[Mr. Badwrench]

Another helpful trick: For larger holes, start off small and work your way up. So if you need a half inch hole for example, start off by drilling a 1/4" hole, then step up your drill size 1/16" at a time until you get to 1/2". It reduces the chance that the web of the drill will grab the plastic as it breaks through, and crack it.

Coated tools, such as titanium nitride, (TiN), titanium aluminum nitride, (TiAlN), titanium carbide nitride, (TiCN), or LubriPlate, don't really do you any favors when cutting plastic. These coatings are specially designed to increase tool life when cutting hard materials, such as inconel, hastalloy, hardened tool steels, or some of the harder stainless steels. If anything they are worse when cutting plastic than just ordinary high speed steel. The coating adds a tiny layer to the edge of the tool, making it a tiny bit less sharp than uncoated tools. They don't have anything to do with heat distribution while cutting, that is almost entirely governed by tool speed. As others have said, keep the speed as slow as possible- it is best not to use a Dremel at all. If you must use a Dremel, use a speed governer with it, and neck the speed down as far as it will go.

[Andrew Gorman]

Drill them by hand! Either chuck the bit into a pin vise, or for larger sizes I use a drill chuck as a giant pin vise. A taper reamer is useful to get the hole to the final size you want. If you are using a power tool without a speed control. it just won't make a clean hole.

[srspicer]

The best Dremel to use is the old school foot control with the flex shaft and hand piece. The smaller self-contained drills do not give you the ultimate control, but if you take your time, you'll do fine.

Ditto on all the advice. Good luck.

Scott

[Chacal]

I use a cordless screwdriver with a chuck. Slow speed, clean holes. I usually get two nicely shaped spiral shavings—one per cutting edge on the drill bit—with each hole I drill, meaning the bit cuts cleanly.

[Warped Speedster]

Sometimes when drilling into soft plastic, like "Evergreen," it's very easy for your drill bit to drift while it's plowing through the plastic, especially with larger bits. Single edged unibits are notorious for that--where the hole ends up not being exactly where you wanted it to be. I'm not talking about a center punch problem, I'm talking about the bit cutting unevenly through the plastic once it gets started.

So I've been using a drafting compass to first "draw the hole" on the plastic as a guide. I then drill the hole as closely centered in the circle as possible and then finish it with a hand reamer.

Reamers are a good way to finish up a hole. And, if you can find them, they make very small needle reamers too. They're great for trueing up very tiny holes to exact size.

I found my last set of needle reamers at the "Great American Train Show" (GATS) where some of the venders there used to sell some really neat tools.

[Kylwell]

And of course, Micro Mark sells them.

[Lt. Z0mBe]

Drill by hand using a pin vise. Seriously. It's not that big of a deal and you'll find the amount of control you gain far outstrips the 30 seconds you gain from using the rotary tool. The only time I go to the Dremel for drilling is when drilling through metal or really, really thick plastic or other substrate. Then, to avoid the ridge and ribbon, I add a drop of water to the bit, remove the bit as it evaporates and reseat, adding more water until I am through. For large holes, I step up the bits to avoid splintering holes in plastic; with metals, I just use the correct bit at the start.

Finally, make sure, as others have stated, you start with a pilot hole set with a pin chucked in a vise or knife handle.

I hope this helps.

Kenny

[Kolschey]

I've been using a pin vise myself for the past year or so, and it quite simply gives you far more control than a motor tool, let alone a drill, with none of the melting or deforming issues.

For thicker stock, I find that this works really nicely:

http://www2.fiskars.com/Products/Crafti ... Hand-Drill

This allows you full control over the speed of any drilling job.

To start a hole, this is the sort of bit I sometimes use- a reaming burr like number DRE125 on this page:

http://www.hobbyplace.com/tools/drebits.php

[en'til Zog]

This NEEDS to be a a sticky. It's such a basic problem.

[Warped Speedster]

I agree with using pin vise drills for making the most accurate holes. In some instances I'll start a tiny hole like that with a new exacto blade--just a couple turns, very lightly, to give it an exact center point to drill in.

I guess you could center punch with a needle chucked up in a pin vise too, like Kenny said. Good idea.

[MillenniumFalsehood]

Ditto on the pin-vise. There's quite simply no other way to ensure accuracy and clean cuts on a model. I use them for everything from drilling to making starter holes for cutting. I would advise against using a Dremel for anything other than brute force cutting, as in stuff you don't care about messing up such as removing bulkheads for lighting, carving into resin, and battle damage.

[Ace Airspeed]

Pin Vise.