What tool to make altimeter holes-ARC rockets?

[tina_NM]

I am an instructor for several ARC teams and we really need to reduce our variability in max altitude. As I am learning more details about altimeters the recommended hole size is 0.02" or about 0.5mm. We had been just punching 4 holes with an awl equally spaced around the tube about 3-5mm in size.

I am thinking of trying a sharp needle to make the four small holes of 0.5mm. Any other suggestions? Thanks.

 

[Pinetree]

Me personally, I drill a 1/8” hole, but here's a handy calculator.


https://rocketrycalculator.com/rocketry-calculator/test-vent-port/

 

[Antares JS]

I am an instructor for several ARC teams and we really need to reduce our variability in max altitude. As I am learning more details about altimeters the recommended hole size is 0.02" or about 0.5mm. We had been just punching 4 holes with an awl equally spaced around the tube about 3-5mm in size.

I am thinking of trying a sharp needle to make the four small holes of 0.5mm. Any other suggestions? Thanks.

Holes being too small is a problem. Holes being too big is really not. Just use a power drill with a 1/16" or so bit.

 

[SolarYellow]

https://www.amazon.com/KINGFOREST-Casting-Manual-Jewelry-Assembling/dp/B08NHJDWWW/
I like to drill the holes after primer so they don't get munged up with paint. The paint that's on the tube leaves something like a sorta crisp edge if you go slowly and carefully. Add a drop of thin CA after drilling to harden up the fibers on the edge/back of the hole. When the CA hardens, run the drill through again. After final paint, run the drill through again.

Holes being too big can be a problem if it leads to excessive air currents in the altimeter chamber. I think more, smaller holes is better to have lower velocity, smaller streams of air in more directions.

The altimeter should be protected against both airflow and sunlight.

 

[tina_NM]

Me personally, I drill a 1/8” hole, but here's a handy calculator.


https://rocketrycalculator.com/rocketry-calculator/test-vent-port/

Thanks. The ARC materials talk about large vent holes causing wind noise in the data. So I thought I would ask around for people's actual experience.

 

[tina_NM]

Holes being too small is a problem. Holes being too big is really not. Just use a power drill with a 1/16" or so bit.

Thanks. 1/16" drill bit seems a practical size. Materials provided by ARC states holes that are too large can cause wind noise in the data. We are trying to get to a point of consistency, so we can improve our performance. Thanks for some actual experience.

 

[tina_NM]

https://www.amazon.com/KINGFOREST-Casting-Manual-Jewelry-Assembling/dp/B08NHJDWWW/
I like to drill the holes after primer so they don't get munged up with paint. The paint that's on the tube leaves something like a sorta crisp edge if you go slowly and carefully. Add a drop of thin CA after drilling to harden up the fibers on the edge/back of the hole. When the CA hardens, run the drill through again. After final paint, run the drill through again.

Holes being too big can be a problem if it leads to excessive air currents in the altimeter chamber. I think more, smaller holes is better to have lower velocity, smaller streams of air in more directions.

The altimeter should be protected against both airflow and sunlight.

Thank you for the clear, specific advice! Incremental improvement here we come!

 

[Antares JS]

The only thing I can think of is maybe that wind noise would be a problem if your altimeter is right up against the vent hole.

 

[Wrightme43]

I want to offer a woodworking trick. Bradpoint drill bits. They have a center point and two outer spur cutters. Barely start the center point and then by hand spin the bit backwards to use the outer spur cutters to create a clean hole edge, the cut thru by hand to prevent a mess on the inside.


I don't know much, but this I do know.

 

[dhbarr]

For cardboard I usually twist a 1/16" bit by hand, apply thin CA to stiffen up any fuzzies, then re-twist. EZ PZ.

 

[waltr]

For cardboard I usually twist a 1/16" bit by hand, apply thin CA to stiffen up any fuzzies, then re-twist. EZ PZ.

That is how I drill holes in BTs.