drilling fiberglass fan shroud

[jtkkz]

I bought a new amber fan shroud....

what is the best way / tools used to drill holes in it...

Multi-flute reamer?

Helix drill bit?

[gestalt1]

a regular drill bit will tear it up and crack the fg too much. i used a zip saw - used for cutting drywall for outlets etc.. worked great.
-matt

[jmshepard]

I used a Unibit step drill. They work great on all plastics.

[jtkkz]

Originally posted by jmshepard
I used a Unibit step drill. They work great on all plastics.

Do you still need to drill a small pilot hole first, then use the unibit step bit to drill the bigger holes..?

[jtkkz]

Will this work fine with my fan shroud?

IRWIN 10233 UNIBIT 3, 9 Hole Sizes 1/4-Inch-3/4-Inch in 1/16-Inch Increments

Ideal for drilling holes into thin materials such as stainless steel, copper, brass, aluminum, plastic and laminates

[Early_S_Man]

Dremel Tool & carbide PC board router bit ... a tiny version of a Roto-Zip bit.

http://www.goldmine-elec-products.com/prodinfo.asp?number=G15898

[jmshepard]

I used a similar Unibit the other night on my shroud.
It was the bit with the smaller series of holes.
I did not drill a pilot hole.
Jim S.

[jtkkz]

How do we drill the bigger holes 3/4"

[jmshepard]

I would buy two Unibits. Use the smaller to start a pilot, finish with the larger to 3/4".
Jim S.

[Johnb911]

If in doubt drill plastics and fiberglass at highspeed backward.
Especially the first and last bit.
Its slow but it won't chip or tear on the way in or out the otherside.

It's also a good idea to drill untill the tip gets through and then flip it over and drill from the other side.

That way you are in the middle of the glass when you grab the last bit with the drill. Less chance of tearing.

[island911]

Well heres a re post of mine...

Originally posted by island911
here you go, 5-x . . .

the diamond shape toothed Tungsten Carbide Cutter;



and, far from your average drill bit;


'nuff detail of the cutter geometry?

I suposse, next your going to ask for speed & feed rates.

(2800rpm @ 1.5thou/rev)

But really, for the bigger holes, think about composites being most like wood ... lots of wood-bits out there. (typical Forstner or spade bits)

For the small stuff Warren has it right, Carbide Dremel bits.

[tctnd]

Cheap chinese "forstner" bits work great for larger (3/8" up) holes.
regards,
Phil

[haycait911]

for small holes 'blair' bits work well, basically a small hole saw. for larger holes, 1/2 inch up, well, a hole saw. but a sharp one! It's also a good idea to drill untill the tip gets through and then flip it over and drill from the other side.- very good advice. Don.

[The Turk]

I just used this the other night to make a ¾” hole, it worked great, I got it at Home Depot.

Good Luck.