Heat bending polycarbonate for a windscreen

[Troy]

Gary, that's a fine looking machine. But shouldn't the picture maybe go in the "Hooters" thread?

[Guest Gary Cheek]

Hooters for sure! The hooters were There was a celebrity named Dagmar who was quite well endowed. THe Cyclone wans nic-named Dagmar when it was being built.

[dlaing]

[mike wilson]

Eh? Enlighten me, por favor? I thought a properly ground bit was a sharp bit??

 

I use a "Drill Doctor" bit grinder.

 

To describe it simply, you want a bit that ends up looking similar to a masonry drill. The cutting faces of a normal twist drill need to be ground back with a whetstone so that they are less of a sharp point. It's one of those things that is very difficult to put into words and indescribably easy to show someone. I'll see if I can find a website with the information in diagram form.

 

Once the bit is properly formed, it will be much easier than farting about with hot needles. Not to mention safer.

[mike wilson]

Good article here:

http://www.newmantools.com/machines/drillpoint.html

 

If you go down to diagram "N" you can see what I mean about backing off the cutting edge. Bring the point (in cross section) of the edge back until you have something that makes more of a planing action than a cutting one.

 

A fine whetstone run parallel to the longitudinal axis of the bit will work nicely in a couple of strokes.

 

HTH.

[Guest ratchethack]

Thanks, Mike. I understand the principle:

 

"A reduced chisel as in fig. L and increasing or decreasing the rake accordingly permits a dubbed point to drill hard or soft metals, bakelite, fiberglass, plexiglass, copper or brass."

 

Not sure if I'm even able to achieve ideal bit dimensions for the task with the Drill MD, but knowing the dynamics at work will help prevent problems, and I'll certainly give a sharpened bit some attention with a whetstone. Since there's only 6 holes to be concerned about, not production quantities, I reckon I can put some additional care & attention on top o' the knowledge to achieve a good result.

[Guest Gary Cheek]

As Mike siad. Just a few licks on the whet-stone will do the trick well enough. It doesn't take much of a flat. If you can see it with 60 year old eyes, it'll do.

[Steve G.]

As Mike siad. Just a few licks on the whet-stone will do the trick well enough. It doesn't take much of a flat. If you can see it with 60 year old eyes, it'll do.

So, are you guys talking about drilling poly or acrylic? If it's poly, any drill will do, even a frickin' wood hole saw, it will work with anything, ANY type of poly. Drilling acrylic? ANY type of acrylic?? No matter which drill you use, or how you modify it, you stand the risk of cracking it. Believe me, I do it every day, today!!

Ciao, Steve

[Guest Gary Cheek]

Yes, any drill "will do" in polycarbonates but some work better than others.Grabbing excessive self feeding and hogging should be avoided for professional appearing results. Hole saws work well as do Unibits (latter with thin material) As you get more experience with acrylics you learn to work them too without cracking . Properly tempered material Using the right tools and techniques with properly tempered materials are a must . In this business we seldom have near enough time to do it over. Breaking parts is not an option.

[Steve G.]

Yes, any drill "will do" in polycarbonates but some work better than others.Grabbing excessive self feeding and hogging should be avoided for professional appearing results. Hole saws work well as do Unibits (latter with thin material) As you get more experience with acrylics you learn to work them too without cracking . Properly tempered material Using the right tools and techniques with properly tempered materials are a must . In this business we seldom have near enough time to do it over. Breaking parts is not an option.

 

The same can be said for my business. I recently fitted/installed a new roof dome on a Messerschmitt 3 wheeled car. There was no room for error!!

Ciao, Steve