Tips on drilling clear glass needed!

[beachbowhunter]

I just finished my first set of TD limbs and one of the difficulties I had was chipping/splintering around the drill holes. I use a great jig and the holes are nicely aligned.  How do you avoid the chipping?  Do you drill fast or slow? Drill press or hand drill? Any recommendations on drill bits?

thanks!

[psychmonky]

Never built a glass bow, but could you use masking tape? Put it on the spot to be drilled and then drill through it and remove after your holes are there? Might be worth a shot.

[Sharp Shooter]

I have the same problem, masking tape helps, also use a drill bit that scores the outside edge of the hole. I think their called a brad point bits. They work better for me. Tony

[Bradford]

going in the glass usually is not the problem..it is coming out the other side.  I make sure there is a piece of wood tight to the bottom of my limb..and i go slow.. i still get a splinter now and then but that is what super glue is for

[D]

I had the same problem. My fix...drill with a small bit first to get an alignment hole then drill through the glass with the drill in reverse, then when your in the wood drill in foward then use the small hole as a guide on the other side so you can reverse drill through the glass on the other side.  I hope that makes sence.  Has anybody tried Forsner bits??  I've never tried them on glass

[perry f.]

Bradford, how do you fix it with super glue?

[Sharp Shooter]

Another thing I've discovered the hard way, once you drill the holes through the limb, use a reamer an bevel the holes and apply super glue to the bevel. This will help prevent the glass from splitting farther down the limb. Hasn't happened a lot but can. Tony

[Bradford]

Just like sharp shooter... Most of the time the splinter is still there.. I apply a small amount of superglue under the sliver.. or just around the hole if there is no splinters and let it dry.  It holds it all together and seals it up.

[D]

I just tried a forstner bit on a scrap piece I had that I cut off the limb when I glued it up and it didn't splinter bad at all.  I didn't clamp it down or anything just pressed it down against my bench.  The exit hole didn't even splinter much either.

[beachbowhunter]

I used masking tape and had a piece of wood beneath and tight but still had splintering. I did seal everything with super glue.  

I have heard of something called "pilot bits". Anybody know what those are. I don't know what a Forstner bit is.

[Crooked Stic]

Use sharp bits. Clamp a hardwood piece underneath and dont force it. Countersink the hole on each side with a grinding stone mounted in a drill.

[D]

Drilling with the drill in reverse just to get through the glass gives the cleanest how I've found yet.  I'm sure its not good on the bits but they are cheeper than glass.

[kennym]

The best bit I ever had , and don't know if they still make em, was a black and decker from the department store called a bullet point(I think)

It was kind of like a brad point, but for metal (or glass) , had a  lil point in center and then the edges cut first, worked lke a champ.

They may not still be the same, but I found some here..

  http://www.amazon.com/dp/B000PIVM9U/ref=asc_df_B000PIVM9U2324474?smid=AM0TJKCE8MD21&tag=sdcbing4-20&linkCode=asn&creative=395105&creativeASIN=B000PIVM9U  

You cant see the end of the bit, but the pic on the package kind of shows it better.
If anyone tries em, let us know how they work...

[4runr]

Norb, a pilot bit is just a smaller bit than the one used as the final bit.

For example, if your finished size hole is going to be 3/8, first drill a hole with a 1/8 bit.

HOWEVER, if you're using a Forstner or a brad-point, don't drill a pilot hole. Both those bits have a center "point" which the bit uses as a pilot.

[Sigmazxcs]

Haven't dealt with glass yet, but I've quite a bit of experience dealing with similar materials.
A pilot hole is a good solution, but be sure to align the surface parallel to the drilling platform, otherwise, god have mercy on you.

[D]

Hey Kenny Lowes has those pilot point bits.  I bought a whole Dewalt kit of them.  Pretty cheep too.  But I used one of them and it splintered the glass. Ya know I never thought about it til now they actually make a drill bit for glass.  To drill in mirrors to hang on walls.  They actually look like two blade broadhead on a shaft.  I've never tried them.  I knew they had them but never even thought about them.  I've seen them at Lowes but I can't remember what size they were.  Heres an example
 http://www.amazon.com/Vermont-American-13310-4-Piece-Glass/dp/B000ETWIKM/ref=sr_1_7?ie=UTF8&qid=1357087929&sr=8-7&keywords=glass+drill+bit

[Roy from Pa]

Ifin you boys made real bows outta wood, ya wouldn't haf ta worry about such trivial things          ...

[kennym]

But Roy, we would haf to make so danged many to get just one.        

Hmm, were you drilling just the glass, or a glued up limb?  I always just drill slowly til it turns white on the back side then drill from the other way. This is on limbs glued up tho.

[beachbowhunter]

They call them lip and spur bits or brad points according to Wikipedia. Are those the ones you have tried?  The description of how it Cuts fibers is interesting.

[beachbowhunter]

Definitely not like the Lowes link from D. Can't post a picture from my phone.

Like these?

 http://www.traditionalwoodworker.com/COLT-5-Star-Brad-Point-Bits-Inches-HSS-Germany/products/725/