Drilling holes in clear plastic parts...

[CountryJoe]

  I'm building a pro mod car and would like to try putting holes in the side windows. I've seen these on the actual cars {no idea what they are for}  but they seem like a nice touch. Now, the clears parts have never been something I've ever had very much luck with...  I've chipped more of these suckers than I'd ever care to mention.

  It just seems to me that they would be something that wouldn't take very kindly to a drill bit. Is this possible or should I be looking for some other material to make windows out of?

[Tom Geiger]

What I'd try...   Take the side glass and cover both sides with masking tape.  That will add to the rigidity and protect the glass from scratching.  Put the glass on a wood surface (one that is okay to drill into). If it curves, turn it so that the area you are drilling is right on the wood surface, you don't want it flexing.  Then drill a small hole in it.  Once you are through, progress with larger bits, until you get to the size of the hole you want.  I wouldn't just go small hole then big hole to avoid stress on the glass. Then remove the masking tape and hope for the best.  Good luck.  

[Ace-Garageguy]

Using conventional drill bits to drill clear plastic is almost guaranteed to shatter and crack the material. Tom's suggestions of using masking tape and carefully supporting the work are good, but experiment on scrap material...that is IDENTICAL to the kit plastic you want to drill... FIRST.

Special drill bits that are far less likely to crack and shatter clear materials have been devised.    http://www.eplastics.com/plexiglass_lexan_plastic_drill_bits

A good way to avoid the problem entirely, and make scale-thickness windows, is to use clear plastic or acetate sheet, and use a hole-punch to form your holes. The old standard paper-punch works fine for this, and they can be found in various sizes.

Gasket-punches also work beautifully.   

Edited October 11, 2015 by Ace-Garageguy

[Tom Geiger]

I've done holes in clear plastic as I described. I believe I've avoided cracking the glass because I started with a very small hole cushioned with tape. The tape also gives your first bit something to hold it in place so it doesn't skip off your intended point. I then went up one bit size at a time to enlarge the hole. That was done to minimize stress on the plastic by taking out a little bit at a time.

As per Bill, practice on scrap first!  And his advise on making glass from acetate sheet is good,  my favorite is Evergreen clear sheet for that.

 

[Ace-Garageguy]

An important thing to remember when using conventional bits as per Tom's method...or even the special bits for plastics...go slow. Normal drill bits are designed to 'bite' into the material, while the special bits for plastic have a differently-angled tip that "shaves" material out of the hole, far less aggressively than standard bits do. When a bit bites too deep, it will force itself farther into the hole than there's room for, and the material, much weaker than metal and unable to stretch, will crack.

Whatever bit you use, if the bit is pushed too fast or too hard, and it digs into the material, it WILL crack.

Cracking also occurs frequently when the bit breaks through the back side of the hole, as it can easily become wedged and split the material at this time. Tom's suggestion of supporting the backside of the material with tape, AND making sure the drilling location is flat on the backing surface, are both VERY important to avoid cracking...especially if you elect to try to use conventional bits.

I learned about the special plastic bits back in the early '70s, working for a Datsun dealership installing clear headlight covers on the then-new 240Z. The cover kits came with special bits, but the other mechanics didn't bother to use them or read the instructions. They also ate a bunch of headlight covers they'd ruined.

Over the years, I've installed many, many very expensive aircraft and race-car screens and windows, and have come to rely on the special bits for cheap insurance.

Edited October 11, 2015 by Ace-Garageguy

[sjordan2]

  I'm building a pro mod car and would like to try putting holes in the side windows. I've seen these on the actual cars {no idea what they are for}  but they seem like a nice touch. Now, the clears parts have never been something I've ever had very much luck with...  I've chipped more of these suckers than I'd ever care to mention.

  It just seems to me that they would be something that wouldn't take very kindly to a drill bit. Is this possible or should I be looking for some other material to make windows out of?

Different kinds of cars have different size holes, including some with plexi flaps and small holes. Do you have a reference picture?

Edited October 11, 2015 by sjordan2

[Art Anderson]

For starters, the clear plastic used in model car kit "glass" is pure styrene, which itself is very brittle!  You can drill holes in it--I've done that in years past, but it takes PATIENCE!  I'm not sure just how large a hole you want to drill, but as others have stated, for holes larger than what you can drill with a pin vise, it does take PATIENCE, and drilling consecutive larger guide holes.  This is NOT a job for your Craftsman electric drill though!

Twist drill bits tend to PULL themselves into the work--pretty simple as their cutting edges are in fact a "wedge".  So, TAKE your time, start with a small bit, do not force it, let it gently cut its way into the plastic, and once that hole is drilled clear through, and you want it larger, repeat the same process, with successively larger drill bits, all the while letting the drill bit do its thing with NO pressure from you.  Doing this by hand will allow you to control how fast the bit drills or enlarges the hole, and trust me, it can be done with absolutely NO cracking of the surrounding clear plastic!

Art

[SfanGoch]

I've noticed that "drill" has been used. If you mean using a power tool, like a Dremel, therein lies the problem. That's plain overkill and you're asking for trouble, especially with clear styrene..Use a pin vise. You won't have to worry about excessive bit speeds melting or cracking the clear plastic. You also won't have to be concerned about the bit jumping, either. You have complete control of bit speed and making sure the bit stays where it's supposed to stay. Use the needle on a compass to mark the center of the hole to be drilled and the bit won't skip. I've hand-drilled through .8mm acrylic sheet and various thicknesses of clear styrene and acetate with no cracks, no melting, no burrs.

[Ace-Garageguy]

There IS a method that will work with a Dremel, but it's not for the faint-of-heart. I've successfully 'melt-bored' large-scale-diameter holes in clear styrene by using a tapered grinder bit in my Dremel, and a fairly high speed.

A tapered bit allows you to bore the hole slightly undersize, remove the melted flash with a sharp X-acto, and bring it up to final diameter with files worked at 90deg to the surface, NOT rotated in the hole. A tapered file that's a close fit in the hole, if rotated, can also dig in and crack the material. Finish-polish the final edge with sandpaper rolls, wet.

And as SfanGoch and Art Anderson both caution, do NOT try to power-drill a hole in clear styrene.

Edited October 11, 2015 by Ace-Garageguy

[Muncie]

Have to agree with these tips - no power - all of the holes that I drill are done with  pin vise - starting small and working up in small steps. 

I believe the hole in the window that you are making is a minimum 6" diameter opening for the safety crews to access the interior with a fire extinguisher.  That's about 1/4" in scale.  At that size, it is difficult to get a round hole in plastic with a drill bit.  Best to get up close to size with a drill and finish with a round file.  take it easy - not much pressure

 

[StevenGuthmiller]

Wouldn't it be just as easy to make new glass out of clear acetate or "lay film"?

After all, if it's side glass, it's most likely flat anyway.

I use .007 lay film for side glass on occasion. I'm sure it would be very easy to drill holes in.

 

Steve

[Ace-Garageguy]

Wouldn't it be just as easy to make new glass out of clear acetate or "lay film"?

After all, if it's side glass, it's most likely flat anyway.

I use .007 lay film for side glass on occasion. I'm sure it would be very easy to drill holes in.

Drilling small, pin-vise size holes, around .015"-.045" holes is indeed very easy in thin material.

Drilling 1/4 inch holes in material that thin is next to impossible, as the flutes of the drill bit catch and tear the material. This even occurs when drilling soft, thin metals (and even thin steel sheet)...

...which is why, in the third post from the top, I recommended to use some type of punch tool to make holes of the necessary diameter in thin styrene or acetate sheet.

[StevenGuthmiller]

Drilling small, pin-vise size holes, around .015"-.045" holes is indeed very easy in thin material.

Drilling 1/4 inch holes in material that thin is next to impossible, as the flutes of the drill bit catch and tear the material. This even occurs when drilling soft, thin metals (and even thin steel sheet)...

...which is why, in the third post from the top, I recommended to use some type of punch tool to make holes of the necessary diameter in thin styrene or acetate sheet.

You're probably right.

A punch used on the .007 lay film seems like an easy solution.

 

Steve

[ChrisBcritter]

+1 for using the thin material - big reason being that the thickness of the glass will be obvious when a hole is drilled through it.

[afx]

I drilled these holes using a Dremel ball bit turned with my fingers.  Started with a small bit and gradually worked up to the size I needed.

[Helper Monkey]

I am not sure it will work for model parts but i have used a power drill on acrylics and lexans. I used masking tape on both sides and then sandwiched the plastic between 2 pieces of wood and drilled through both. Make sure to keep the wood clamped together really tight. 

[peteski]

I am not sure it will work for model parts but i have used a power drill on acrylics and lexans. I used masking tape on both sides and then sandwiched the plastic between 2 pieces of wood and drilled through both. Make sure to keep the wood clamped together really tight. 

That method does work well for any flat piece of plastic or even sheet metal. But most model car windows are curved )often compound curves) so they cannot be clamped between to flat pieces of wood. 

[Helper Monkey]

I figured that is why it would not work.

If you really wanted to, one could carve the wood to have the same curve as the parts. It is a lot of work. I do not think anyone would do that. 

 

[SfanGoch]

You can support the curvature of the plastic glass by placing modeling clay underneath the part and packing it to completely fill the area. Hopefully, you'll use a pin vise so there won't be any heat generated and there won't be much force applied when drilling. Once you're finished, gently remove the clay and clean up with some 91% IPA.

[Ace-Garageguy]

 ..clean up with some 91% IPA.

A simply tragic waste of India Pale Ale.

Far as pin-vises go, I've not seen one that will hold a bit larger than 3/32" or 1/8", so to get the 1/4" holes mentioned, it's necessary to use a standard twist-drill in your fingers...not the easiest thing to do. Perhaps obtain a small drill chuck to make handling the larger bits easier, and to give a little more leverage?

Supporting the area to be drilled with clay, maybe even masking tape directly on the glass and THEN clay, seems like a good idea. Gots to try it.

 

[SfanGoch]

A simply tragic waste of India Pale Ale.

Far as pin-vises go, I've not seen one that will hold a bit larger than 3/32" or 1/8", so to get the 1/4" holes mentioned, it's necessary to use a standard twist-drill in your fingers...not the easiest thing to do. Perhaps obtain a small drill chuck to make handling the larger bits easier, and to give a little more leverage?

Supporting the area to be drilled with clay, maybe even masking tape directly on the glass and THEN clay, seems like a good idea. Gots to try it.

 

Agree about the twist drills. I also use them if I need a hole as large as 1/4". 

 

I meant isopropyl alcohol. Using India Pale Ale to clean a model is a capital offense in most of the U.S. and its territories. I'm not sure about the U.S. Virgin Islands, though. They consider overproof rum a breakfast drink.

[Muncie]

yep, always rob the chuck off an old burned up power drill before you throw it away - there is usually a hole in the motor shaft behind the chuck - slide pin in the shaft and the chuck should unscrew - makes a good handle for larger drill bits - one of those stepped uni-bits works really well but spendy - the steps seem to be the right increment to enlarge a hole without doing damage.