Need Help!- Drilling a Paddle Racket (fiberglass+foam)

[PEU]

Hi, I need help drilling a Paddle Racket, this racket outside shell is fiberglass and core is EVA foam, other lighter foams are used too, for example polypropylene foam.
Im using a Syil X4+ machine with a spindle capable of 3000 RPM

I'm having a hard time trying to make a clean, nice and straight hole, I tried with HSS 2 and 4 flute endmills and 2 and 4 flute carbide endmill and the results are more or less the same and they are not satisfactory, here is the sacrifice racket Im using for tests:



and this is a macro shot of how the holes are finished:



As you can see there are concentrical bands that make the hole "not nice/not straight" I guess that happens due to material not finding a proper exit and revolving around the mill while its drilling.

Then I found this video, but I never saw a tool like that, the cuts look nice, I would like to know what kind of tool is that, or what is the best way to drill this racket using my machine (remember, fiberglass shell + eva foam core)

YouTube - Agujeros Paddle

YouTube - Agujeros Paddle

Thanks a lot in advance!!


Pablo

[PEU]

Any pointer would be really appreciated, thanks!

[John Welden]

I've used a carbide spade bits in carbon fiber and there was virtually no breakout on the back side. Haven't gone through foam + composite before. Problem is that we ran coolant, not sure if your foam would like that.

I've also used "endmills" that are just a rod coated with diamond grit. They work great but like before, we ran coolant.

Maybe you could water jet cut your holes?

If you have to run the cutters dry, I'm not sure what the best way to do it would be.

[PEU]

thanks for the suggestions, yes, we tried waterjet, its a clean cut, BUT, it detaches the composite from the foam on the exit side leaving a small bubble around the hole. This has to be done dry.

I also tought of spades, but the ones I found aren't as pointy like the ones in the video.

[John Welden]

Originally Posted by peu thanks for the suggestions, yes, we tried waterjet, its a clean cut, BUT, it detaches the composite from the foam on the exit side leaving a small bubble around the hole. This has to be done dry. I also tought of spades, but the ones I found aren't as pointy like the ones in the video.

It was years ago but I just remembered that we had a spade bit end, custom ground into a carbide reamer. Again, I'm not sure it would work to run them dry.

[LaserImage]

I would send a link of that video to bits-n-bits or Hartlauer and ask if they know what it is or if they can make it.

Gary