Here is a template for drilling evenly spaced holes for your N-Filter.
I posted this in my pack build awhile ago and it seemed to be popular, so I wanted to make it easier to find. If you’re building a plastic N-filter, I link to the tubing I used for mine on that thread.
Print the template at 1:1 scale (don’t fit-to-page) and cut along the outside. I’ve left some overlap in the template so that you can tape one end to your tubing. Wrap the template around the outside, and then tape the other end down. Make sure you drill small pilot holes in the center of each circle first. Then go back and drill your 1/2" holes.
There are two templates, depending on the size of your N-Filter. If there is another common size, let me know and I will add a template for it.
The holes are equidistant on the templates. If you want to make two holes closer together (and the rest equal) you could always print the template out a little larger, so it overlaps itself just a little bit more.
Used your template to drill my N-filter holes today. It was one of those times when it was just so nice to not even have to think about figuring out measurements! Thanks a lot Namssorg!
There are a few reasons. Sometimes people just want to replace it with a metal N-filter. Some of us have older shells built before the exact dimensions and placement of the N-filter were available, and some of us have shells that do not include an N-filter at all.
In my case, I just didn’t like the N-filter that came with my Shell. It was sightly too small, and didn’t look like I wanted it to, so I built my own!
Wow this is great! How do you actually cut the filter to fit onto the cyclo though, would be really helpful if there was a template for this. I know all packs vary slightly but some sort of guide would be awesome
That’s a great question. If you have a contour gauge, that would help a little:
I didn’t have one, so what I did was cut apart a cereal box, and cut out a few rectangles that with the ends taped together, made tubes the same diameter as my N-filter.
Then I just carefully measured and cut out the profile of my cyclotron out of the cardboard. It took some trial and error, but eventually I got a ‘paper’ n-filter that had the right profile of my cut. I wrapped it around my actual N-filter and used it to trace on guides that I used for my cuts.
Hey guys- Long time! Just wanted to call out that I’ve slightly updated the 3" filter template. I actually did this awhile ago, but forgot to mention it here.
The 3" template now has two options- an evenly spaced version, and a “GB1 Movie Spacing” version with two holes closer together, like on the Minnesota pack. The link to the full-size PDF is in the original post on this thread.
Thanks to Drjameshouse who provided the measurements and encouraged me to put this together.
Another minor update- The files have not changed, but the public Dropbox links have stopped working. I’m now hosting these on Google Drive if anyone still needs them!
