threaded holes?

Korndog · Mar 6, 2004

i wanna make threaded holes on my res (acrylic).
i'm not sure what kind of drill bit to use for it.. My uncle left a huge box of drill bits and some look like they can do some niffty stuff, i don't have a drill right now (loaning it) but once i get it back i'm going to start drilling away..
does anyone know what kind i should use? if i dont' have it, does anyone know where they sell them?

thx guys!

edit:: okey, i'm a moron.. threaded drill looks like an inverted thread hole. duh. but i still can't find any.. i'm finding threaded drill bits that attach with the threaded end (useless) besides the fact its only small size.

Joe Camel · Mar 6, 2004

to get threads into a hole you use a tap. its like .... ill find a pic brb...

http://www.grainger.com/Grainger/productdetail.jsp?xi=xi&ItemId=1611768790&ccitem=

google gave this: i havent read it but i thik it should give u a great start: http://www.sheldonbrown.com/tooltips/taps.html

they assume your tapping metal. the stuff you want to tap will cut easier, but could crack ALOT easier. i would suggest trying to drill (could crack on this step) and tap a few (3-5) holes in some scrap sheet of the SAME plastic/plexy/lexan/acrylic B4 you work on something you DONT want to break!

GOOD LUCK

PS. make sure the tap is at a right angle to the surface, if the tap is off, then the barb you thread in will alos be off angle.

PPS. use lube!! oil, wd-40, spit (J/K), that can help ALOT. they make "tap oil" but i just dip the tap in 10/40 motor oil. note: ive tapped steel & alu. but never acrilic

SysCrusher · Mar 6, 2004

Your going to want 1/4npt tap.

Korndog · Mar 7, 2004

OOOOO tap! learn something new everyday..
thx for the like joe, i actually found a small one, but what i need is a 1/2npt for the 3/4 barb fitting i have
oil? i guess 3n1 oil is fine.. right? sae10? eh.. who cares

Joe Camel · Mar 7, 2004

as long as it (the oil) dosnt damage the acrylic. ie. eat it away.
i dont think it would, but again, i would test.

also, are you making holes that are already there bigger? and, are u using a hand drill?

Korndog · Mar 7, 2004

no, no holes yet.
i have a special dril that goes from small to large and was recommened to me by the plastic guy at tap plastics.
its really hard find a 1/2npt tap, argh..

Joe Camel · Mar 7, 2004

huh, i have to drill 7/8" hole into 1/4" plexi-glass cabinet doors @ work and have had "more than one" crack on me. how big does that special drill...drill? (learn something new everyday..)

JFettig · Mar 7, 2004

It sounds like you have a step drill,

Drilling and tapping plexiglass is very risky business, It is very likely youll have it crack on you.

Here is a good link for you:
http://www.carbidedepot.com/formulas-tap-pipe.htm

Jon

slater3333uk · Mar 7, 2004

Il put money on it breaking

sorry but it will

but anyway each size of tap will have a specific size of hole it will work in. Sometimes it will tell you on the tap its self or sometimes you have to look it up in a book (you could probably find it on the net aswell). Its normaly called the tapping drill size.

Posidon42 · Mar 7, 2004

This is not universally true guys. I built a small project box out of 1/4" acrylic and tapped all of the screw holes. None of them cracked on me. You just have to take your time and make sure you drill a big enough starter hole to begin with.

If you are trying to tap into the side of the acrylic, you are going to have to drill the hole about 1/4" deeper than the length of the screw. This is to account for the extra depth you have to tap before it will get to the right diameter for the screw. Just try it out, you will understand later.

Remember to use a some lubrication, always handy

, and try to find something to keep the tap flush with the surface. I ended up making a little jig out of some spare aluminum and a small section of 1/4" ID metal tubing I had lying around and that worked fine. Lightly clamp that to the acrylic and tap away!

Korndog · Mar 7, 2004

well.. i'm going to try tapping the cylinder i got now, it only cost me 3 bucks so i don't mind. If it does crack on me, i'll get a polycarbonate cylinder instead, i've missed around with polycarbonate a bit and that stuff needs some serious pressure to crack. if all eles fails, i guess i gotta just buy something premade

thx for ur help guys!! i'll post pics if i get it to work

Edit: OO i actually found a hole saw, small one.. i think it'll work better then a drill, maybe less pressure/bending, more cutting. yay.
*tosses stepping bit*

VballCoach · Mar 8, 2004

I tapped my res(when I was going to use it...t-line installed now) and I used silicone spray. I used lots of it. After every 1/2 to 3/4 turn on the tap I'd spray silicone liberally. I would blow out the excess material from the tapping with compressed air and then spray silicone and keep 'tapping'. Go slow and don't rush it. I was talking to my uncle who is a machinist and he says there is a way to 'harden' the poly so it stays clear and is hard as a rock. Some type of vapor you 'dip' the poly in. I'm hoping to have him build my a poly top for my w/b's. He says I won't ever have to worry about them cracking then. He says the vapor chemical is very expensive. Good thing he's my uncle....

Korndog · Mar 8, 2004

damn...
hm..
i wonder.. if i heated up the tap (pretty hot like with a 120watt soldering iron

) and then started drilling slowly.. would that be easier and possibly crack-free?

JFettig · Mar 8, 2004

Well, heating it up wouldnt help, those taps are made to cut not push, Did you turn in half turn and out quarter then in half and out quarter?

Jon

Joe Camel · Mar 8, 2004

ya, you have to back the tap out and break the chips you just cut. that way the flutes dont clog up.

keep trying on scrap, youll get a feel for it.

threaded holes?

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