Drilling plexiglass

[Steve B]

I got a 6" square 1/8" piece of plexi to mount the switches on my boat. It
will be set into a 3/4" piece of plywood that I routed out, and stained and
varnished.

I have never had much luck drilling plexi without having it split. Is there
a secret? Sharp blade? High rpm? Very easy pressure? Use a backer piece
of plywood? All the above?

Steve

[chaniarts]

the drill tip has a different angle on it. you can get them at the
plastics shop. i don't think i've ever seen them at a borg.

[tiredofspam]

Brad point bit, very little pressure, medium rpm,
yes backer, always avoid edges, you can be close, but they will crack
over time. cleanout with a counter sink...

[-MIKE-]

All of the above, except high rpm. Go slow. Brad point bits helps.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com
mi...@mikedrumsDOT.com
---remove "DOT" ^^^^ to reply

[-MIKE-]

On 5/31/12 12:13 PM, tiredofspam wrote:
> always avoid edges, you can be close, but they will crack
> over time.

For close to the edge, I've used a soldering iron to melt holes in thin
plexi.
Also, you could drill the holes in a larger piece, first, then cut to
size.

[bw]

"Steve B" <ste...@gmail.com> wrote in message
news:jq887i$i5t$1...@speranza.aioe.org...

http://www.eplastics.com/Plastic/Plexiglass_Lexan_Plastic_Drill_Bits

[Jim Weisgram]

On Thu, 31 May 2012 10:02:51 -0700, "Steve B" <ste...@gmail.com>
wrote:

A drill bit with the right grind?

http://www.rplastics.com/plasticdrill.html

http://www.amazon.com/s?ie=UTF8&tag=mozilla-20&index=blended&link_code=qs&field-keywords=plexiglass%20drill%20bit&sourceid=Mozilla-search

[routerman]

Plexipoint (second up from left: http://patwarner.com/drilling_tools.html
)
with negative rake (HSS) about the best for small holes in AC.
No breakage, clean entry & exits. Don't drill at 10000, however.
They stop working @~1/2" diameter, so if you need a bigger hole then
you need another drill.
118 degree tools will work but demand a backup, slow speed (<250) and
sharpness.
Hi feed rate will bust the plastic. Brad point, Forstner, hole saw?
Rediculous.
(That should start a BM storm)
*********************************************

[Lee Michaels]

> On 5/31/2012 10:02 AM, Steve B wrote:
>> I got a 6" square 1/8" piece of plexi to mount the switches on my boat.
>> It
>> will be set into a 3/4" piece of plywood that I routed out, and stained
>> and
>> varnished.
>>
>> I have never had much luck drilling plexi without having it split. Is
>> there
>> a secret? Sharp blade? High rpm? Very easy pressure? Use a backer
>> piece
>> of plywood? All the above?
>>

Why plexi? Lexan (polycarbonate) is much more forgiving. It is also more
flexible and will stand up to more shock and abuse. And it is much easier
to drill. For such a small piece, you can get something at the borg and cut
it to size with any kind of woodworking saw. I have built a lot of stuff
with lexan. Most of the applications I used would have broken the
Plexiglas. Plexi is not only easy to break, but it can develop cracks over
time. Lexan will change its size slightly with temperature changes, but its
increased strength and durability make it more feasible for many
applications. And if this is going on a boat, I would want something a
little stronger and easier to work with.

My advice, toss the plexi and use lexan instead.

[Swingman]

On 5/31/2012 1:47 PM, Lee Michaels wrote:

>> On 5/31/2012 10:02 AM, Steve B wrote:

>>> I have never had much luck drilling plexi without having it split. Is
>>> there a secret?

> Why plexi? Lexan (polycarbonate) is much more forgiving. It is also more
> flexible and will stand up to more shock and abuse. And it is much
> easier to drill. For such a small piece, you can get something at the
> borg and cut it to size with any kind of woodworking saw. I have built a
> lot of stuff with lexan. Most of the applications I used would have
> broken the Plexiglas. Plexi is not only easy to break, but it can
> develop cracks over time. Lexan will change its size slightly with
> temperature changes, but its increased strength and durability make it
> more feasible for many applications. And if this is going on a boat, I
> would want something a little stronger and easier to work with.
>
> My advice, toss the plexi and use lexan instead.

Bingo ... second the use of Lexan over plexiglass, although it can get
pricey.

I can cut it on the TS with my Forrest WWII, and have drilled it (albeit
small holes for screws) with whatever was in my tool box.

Used Lexan for this "no visible means of support" backlit art glass
shelf for a client, cut to size on the table saw from a 4 x 8 sheet,
about a year ago:

https://picasaweb.google.com/111355467778981859077/EWoodShopBacklitGlassDisplayShelf#5701367237981688482

(cell phone photos, sorry)

--
www.eWoodShop.com
Last update: 4/15/2010
KarlCaillouet@ (the obvious)
http://gplus.to/eWoodShop

[Leon]

Start with a small hole and work up.

[Lew Hodgett]

Steve B wrote:

> I got a 6" square 1/8" piece of plexi to mount the switches on my
> boat.

----------------------------
Plexiglass and boats don't mix.

Use Lexan.

Lew

[Larry Blanchard]

On Thu, 31 May 2012 10:02:51 -0700, Steve B wrote:

> I have never had much luck drilling plexi without having it split. Is
> there a secret? Sharp blade? High rpm? Very easy pressure? Use a
> backer piece of plywood? All the above?

There are special bits, but I've had pretty good luck with a plywood
sandwich.

--
Intelligence is an experiment that failed - G. B. Shaw

[Larry Jaques]

On Thu, 31 May 2012 10:04:28 -0700, chaniarts
<chan...@nospam.yahoo.com> wrote:

>On 5/31/2012 10:02 AM, Steve B wrote:
>> I got a 6" square 1/8" piece of plexi to mount the switches on my boat. It
>> will be set into a 3/4" piece of plywood that I routed out, and stained and
>> varnished.
>>
>> I have never had much luck drilling plexi without having it split. Is there
>> a secret? Sharp blade? High rpm? Very easy pressure? Use a backer piece
>> of plywood? All the above?

With normal metalworking twistbilldrits, use low RPM, light touch,
sharp edges. Backer boards are a very good idea, too. Some forstner
bits work well (small diameter), others don't (like sawtooth styles).

>the drill tip has a different angle on it. you can get them at the
>plastics shop. i don't think i've ever seen them at a borg.

Aha! I didn't know that one.

I used to drill square holes in plastic dashboard with an air drill
and twistbilldrits, but that's not plexi. (I think it was ABS.) I
worked in Phoenix one summer (what an idiot!) installing air
conditioners in brand new trucks. One 118F day, it was only 108 in
the shop with 4 humongous swamp coolers running.

--
Self-development is a higher duty than self-sacrifice.
-- Elizabeth Cady Stanton

[Martin Eastburn]

There is help below - but Dad and I always used a ring of clay -
modeling type - oil base - and water inside. It keeps the plastic
cool - and pec drill. Keep the tips slow. RPM's slow. A fast
turning tip of a drill - the outer cutting edge - can melt plastic
and then it cracks it.

Martin

On 5/31/2012 12:02 PM, Steve B wrote:

[Larry Jaques]

On Thu, 31 May 2012 15:38:00 -0500, Leon <lcb11211@swbelldotnet>
wrote:

That's the _opposite_ of what she said. <domg>

LJ, humming "Lay 'er down, roll 'er over, and do it again."

[m II]

Let's destroy his question so we can give answers he didn't ask for.
Here is his text that was conveniently removed from the OP quote.

"Steve B" wrote in message news:jq887i$i5t$1...@speranza.aioe.org...

I got a 6" square 1/8" piece of plexi to mount the switches on my boat.
It
will be set into a 3/4" piece of plywood that I routed out, and stained
and
varnished."

-------------------

"Swingman" wrote in message
news:qKudnUdcK6dITlrS...@giganews.com...

[Morgans]

"Steve B" wrote in message news:jq887i$i5t$1...@speranza.aioe.org...

**********************
Modify a regular twist bit. The leading edge of the cutting surface of a
normal bit is several degrees, and helps lift the chips away from the cut
and also pulls the bit into the material. That is what you do not want.
Take a cutoff wheel on a dremel tool, and cut that leading edge so it is at
89 or 90 degrees to the material you are cutting. Then, take a little
paint, like white or orange, and paint down in the flutes, so it will be
easy to identify later, and not used for cutting other stuff, and getting
thrown away.
Works well, every time.

-- Jim in NC

[CW]

"Morgans" wrote in message news:jqeejr$sdd$1...@speranza.aioe.org...

==================================================================================
I agree. I have done production drilling on plexi. A neutral rake on a twist
drill works great.

[Twayne]

In news:jqeejr$sdd$1...@speranza.aioe.org,
Morgans <jsmo...@charter.net> typed:

I tried that for grins; and it fails miserably. Std drill bit will work as
below:

Backer piece plus tape applied to the other side where the hole will be has
always worked well here. Speed slow enough to let it cut before it burns the
plastic. Need a sharp bit.

[CW]

"Twayne" wrote in message news:jqfufb$90a$2...@speranza.aioe.org...

In news:jqeejr$sdd$1...@speranza.aioe.org,
Morgans <jsmo...@charter.net> typed:
> "Steve B" wrote in message
> news:jq887i$i5t$1...@speranza.aioe.org...
> I got a 6" square 1/8" piece of plexi to mount the
> switches on my boat. It will be set into a 3/4" piece of
> plywood that I routed out, and stained and varnished.
>
> I have never had much luck drilling plexi without having
> it split. Is there a secret? Sharp blade? High rpm? Very easy pressure?
> Use a backer piece of plywood? All
> the above?
> **********************
> Modify a regular twist bit. The leading edge of the
> cutting surface of a normal bit is several degrees, and
> helps lift the chips away from the cut and also pulls the
> bit into the material. That is what you do not want.
> Take a cutoff wheel on a dremel tool, and cut that
> leading edge so it is at 89 or 90 degrees to the material
> you are cutting. Then, take a little paint, like white
> or orange, and paint down in the flutes, so it will be
> easy to identify later, and not used for cutting other
> stuff, and getting thrown away. Works well, every time.
>
> -- Jim in NC
I tried that for grins; and it fails miserably.

=====================================================================================
Then you ground it wrong.

[Ken Moffett]

"CW" <cma...@earthlink.et> wrote in
news:sKadnWxWzsv6ZVfS...@earthlink.com:

That's how I've done it...especially if I want to tap the
hole. The bits sold by the plastics vendors come in only a
few fractional sizes. I have a set of number bits (tap and
clearence sizes) that I've ground a small flat on the lip,
parallel to the bit axis, so it produces a "scraping" action,
rather than the "shearing" action of normal twist drill bits.
Backing, slow speed, and gentle feed...especially on
breakout. These are also great for drilling brass.
I do have a set of commercial plastics bits (1/8"-1/2"), and
the point angle on them is smaller than twist drills. But
mine work great.

Ken

[Martin Eastburn]

While not a pro way, a circular dam that holds a small amout
of water over the hole site as the drill pecks a hole into
the glass.

Must keep the speed down as the plastic melts. The linear
movement of the circumference is what gets you. The outside
really whips around. But in water it will keep the drill
and plastic cool. Just keep adding drips of water to keep
it full. When the hole is drilled, the water drops through.

Remember it is inches per minute that is important, not RPM.
Slow down the large drills even more than the small ones.

Martin

[Doug White]

Martin Eastburn <lion...@consolidated.net> wrote in
news:qxAzr.130924$eR7....@en-nntp-16.dc1.easynews.com:

A touch of soap in the water also helps.

The problem with drilling most plastics is that they have a nasty
combination of poor thermal conductivity, and high thermal expansion.
That means that once the material starts getting hot, it wants to expand,
but the only place it can go is towards the drill. If the thermal
conductivity was higher, the hole would actually get bigger as the whole
piece expanded. The inward expansion creates more friction, which begats
more expansion, and you can rapidly get a runaway condition leading to
the drill grabbing. You have to keep the plastic & the drill cool enough
that it nevers gets into the runaway condition. Slows speeds, pecking,
and coolant all help.

Doug White

[routerman]

Wow, a real BM storm, a strain @ a gnat, a complication where none
exists.
I drill PC & AC & a lot of other materials; I'm a driller. With a
plexi drill, and the work immobilized, you advance the spinning drill
into the work and make a hole. The exit is as clean as the entry;
what's the deal?
No goo, no lube no clay dams, no diddly, see:
http://patwarner.com/images/machining_plastic_d.jpg

[CW]

"Doug White" wrote in message
news:XnsA06AB61E28846...@69.16.186.7...

=========================================================================
The right speed and the right drill bit is all that is needed.

[CW]

"routerman" wrote in message
news:4ce5c54a-e1d1-44d6...@qq9g2000pbb.googlegroups.com...

=======================================================================
I agree completely.

[Martin Eastburn]

Tap also.
Hum.

Ok - where are the plastic drills you use.
Plastic taps also ?

Martin

On 6/6/2012 5:17 PM, routerman wrote:
>
> Wow, a real BM storm, a strain @ a gnat, a complication where none
> exists.

> I drill PC& AC& a lot of other materials; I'm a driller. With a

[routerman]

Negative raked plexi drills, a dime a dozen at WL fuller.
Taps x the millions, any metal working supply or Fuller. Use through,
3 or 4 fluted HSS. As cheap as the drills.
Expect to pay <5$/tap x ~5/16" or less. No rocket or other science
needed.
*******************************************