Static ports in cardboard

Picked up a tool some time ago and finally used it today. If I only use the smallest 1/8" punch, it's worth the $16 I paid here:
https://www.homedepot.com/p/TEKTON-...XvrK1FvIKBYwrFqi38VLlBoCLOHw_wcB&gclsrc=aw.ds
You can also get these punches in smaller sets for less, this is just the one I had.

I have always hated drilling holes in my rockets, regardless of what they were made of. When you drill out paper rockets, you get fuzzy holes that need treating with CA glue and filing/sanding them smooth. Fiberglass requires a special technique that I have perfected to prevent filaments from splitting out inside the tube.

Today, I'm making static ports for my smaller rockets to fly the estes altimeter. I picked the smallest punch out of the above set and punched out a perfect hole. Backed up internally with an old hammer handle, two smacks with a ball peen hammer and here's what you get:







...

Really??? you think that's a clean hole?
You'll still need to CA and sand to create a decent vent.
Where did you get the 1/8" diameter is the correct size for your rocket? depending on the BT size your working on (Looks to be prehaps a BT-55 ot 60), that 1/8" hole may be way to large. Most Altimeters suggest 3 small vent holes equally spaced around the body. You need to know the volumn of your Alt-bay to determine the size vents needed.
If I'm not mistaken there is a Altimeter vent hole calculator available that can be a big help. can't put my finger on the program at the moment, could have been either www.info-central.org or www.rocketreviews.com (Essence's Model Rocket Reviews).

IIRC the largest vent hole i've ever put in a model body (BT-80) Altimeter-bay or payload section were 3- .046875" (3/64"). Generally for smaller bodies the holes are very small fractional size bits.

Hope this helps a little. I do use small round leather punches like the one pictured to cut exhaust vent holes in Helicopter and Glider model pods.

The cleanest hole (easiest for me) is made with a paper punch. Not sure if you can get them in smaller sizes than the 1/4".
I also use a leather punch. Not the same as a paper punch(not made really for paper), but it does work.
You can get deep paper punches.
Pic 1 leather
Pic 2 long reach paper punch 4" reach

Also, you can use a paper punch to make doohickies..the center part of the hole that got punched out.

My favorite tool is just a sharpened piece of brass tubing - I use 3/32 and 1/8 inch. Back up the spot with a stage coupler, press and twist.

As for hole sizing - for your application three spaced 120 degrees apart like the one you have made will probably make some sense. The Estes altimeter seems to need a REALLY fast pressure drop to actually decide it's been launched. Otherwise you wind up after a flight with it still reading zero.

Micromeister - compared to using a twist drill that's a clean hole. The model is an Estes Firestorm ARF, which is BT-60 based and about a foot long between the fin can and nose cone., and the altimeter will be hanging down in the body with the parachute and wadding. And since Wayco said he was using an Estes altimeter, big vents will increase the chances he gets a reading. And since it's not doing deployment or being used in an altitude competition, chances are it will be close enough.

I only know of one altimeter maker that cautions against making the holes too big. It's not Estes.

BEC said:

My favorite tool is just a sharpened piece of brass tubing - I use 3/32 and 1/8 inch. Back up the spot with a stage coupler, press and twist.

As for hole sizing - for your application three spaced 120 degrees apart like the one you have made will probably make some sense. The Estes altimeter seems to need a REALLY fast pressure drop to actually decide it's been launched. Otherwise you wind up after a flight with it still reading zero.

Micromeister - compared to using a twist drill that's a clean hole. The model is an Estes Firestorm ARF, which is BT-60 based and about a foot long between the fin can and nose cone., and the altimeter will be hanging down in the body with the parachute and wadding. And since Wayco said he was using an Estes altimeter, big vents will increase the chances he gets a reading. And since it's not doing deployment or being used in an altitude competition, chances are it will be close enough.

I only know of one altimeter maker that cautions against making the holes too big. It's not Estes.

Click to expand...

I get your point but the fact is even the Estes Altimeter doesn't need gaping 1/8" vents, As a matter of fact it is one of the only altimeter I know of the really doesn't need vent hole at all, since it is Hanging in the body tube, it reads just fine at ejection where it's dangling in open air below the chute & nose cone.
Several of our club members have this altimeter and don't add any holes to the model. I have one but haven't used it other then on a demonstration table showing the size differences between many different models.

The more important point I was trying to making was if you still have to clean up our punched holes then is particual tool may not be such a great find. As Scottydog mentioned there are better punches out there! Plain old paper punches can be had in 1/8", 3/16" and 1/4" but again 3- 1/8" Holes in a BT-60 is WAY overkill. and smaller punches or compass cut holes do a much cleaner job then single straight leather punches. My sharpened & Stropped Rotary Leather punch tubes cuts an almost clean hole but will still needs a little CA around the edges and very light sanding to clean the minor amount of fuzz.
The best method i've found is with a precision Punch and die sets but they don't work well on very small diameter bodies BT-20 and below as the die is generally larger the the tube.

When I drill vent holes I start by drilling the hole with a regular twist bit, but I drill it slightly smaller than the intended size. I then harden the hole with CA. Finally I use a tapered grinding bit on a Dremel tool to open the hole to its finished size. They come out smooth and round and it doesn't take any specialized tools.

Glad my thread got someone's attention, all comments are appreciated. I had to go back and re-read my first post to check if I actually said that the holes were clean.... I admit I didn't go all anal and try to calculate the volume of my body tube, I just followed the Manufacturer's directions:

"For accurate altitude measurements, it is necessary to create 3 to 4 evenly spaced, 1/8 inch (3 mm) square or round holes, approximately 2 inches (51 mm) below the open end of the body tube or payload section of your rocket. Cut holes using a hobby knife or 1/8 inch (3 mm) drill."

Click to expand...

I like Bernard's idea of using a small brass tube sharpened on the end and twisting a hole. At least this would come closer to the 3/64" hole John suggests. Realistically, I don't sweat the small stuff. Little rockets are fun to fly, but won't get my full attention until they could hurt someone when the deployment sequence fails. All my dual deploy rockets have static ports sized correctly for the avbay, and all rockets 54mm and above have redundant altimeters. If you deplore my perspective, flame away, won't change it, and everybody's opinion is appreciated on my threads.
That's what TRF is all about for me, sharing ideas. Even Scotty dog brought to light a tool I didn't know existed, the long reach paper punch. Looks like it would work, but the size of the hole would be too big for a BT 60 tube. Don't think John's antique leather punch would reach far enough to clear the shoulder of the N/C, let alone the recommended 2 inches Estes suggests, and once again, the hole size would be too big. My two stage Estes firestorm has had 10 successful flights, and one separation that I expected, never did trust those cheap rubber band shock cords, and this one failed on the third flight. Now it has what all my other small rockets use, kevlar. Recovery is very important to me, and all my rockets are built with that in mind. The size and cleanliness of those holes won't affect that, and I'm good with leaving them just the way they are.