Drill Guide for Solid Foam Cylinders

This model, and all related uses of such (ie. as a tool for drilling out foam), is only permitted for personal and/or noncommercial use.  Creative Commons - Attribution - Noncommercial - Share Alike.

Parametric model that can be configured within Autodesk Fusion / Fusion 360.  From the design bar, select “MODIFY” and then “Change Parameters”.  From there you can set the drill diameter, the foam diameter, the height, and so on.

When printing, PLA is fine and recommended, there is no need to use any fancy or more durable filament here like PETG.

As some background, this drill guide is used to drill a hole of a specific diameter through the center of solid pool noodles (or similar foam cylinders) so we can use them to make boffers for boffer combat sports like belegarth, amtgard, dagorhir, darkon, etc.  This way we can match the hole diameter to a specific size of carbon fiber, fiberglass, or golf shaft rod rather than having to deal with typical pool noodles that often have a hole down the center, but one where the diameter is simply too large.

You will need a power drill as well as a long drill, 36" recommended, 24" might be enough if you are making bel half-bats, daggers, or something like that.  The guide can be easily built up in pieces, you will want to print one “complete foam and drill guide” and one or more “complete foam guide” pieces and then join them using them M5 screws.

Note:  There are some “experiental” changes to the model not depicted in the photos.. like adding “air holes” just above the guide that should make it easier when inserting and removing the foam cylinder from the guide.  There is also a more open guide “complete foam guide open 4 (param)” which can make it easier to move the foam cylinder in and out of the guide when the foam cylinder is shorter than the guide itself.  

Recommended Procedure:

1. Set guide_dia_inner and guide_dia_outer.  Save “foam guide (bot)” as a mesh, import it into your slicer of choice, and print it.  Use this small test part to check your foam diameter.  It should be tight around the foam, but not so tight that you can't move it up and down the foam freely.  Repeat this step as necessary.
2. Set drill_dia.  You can try measuring your drill bit with calipers but a good starting point for a 3/8" drill is between 9.3mm and 9.6mm.  Save “drill test 4 (param)” as a mesh, import it into your slicer of choice, and print it.  Get it as close to the drill size as you can, but the drill should be able to fit through this piece and spin freely without resistance.  Repeat this step as necessary.
3. Set height close to the build volume of your printer.  Set guide_height as desired, 100mm to 125mm is a good starting point and you shouldn't need to change this much unless you are using a very short or a very long foam cylinder.  Save “complete foam and drill guide 4 (param)” as a mesh, import it into your slicer of choice, and print it.  Double check to see that the drill can fit completely within the guide and will spin freely when doing so, hopefully it does, but if not you may need to increase the size of drill_dia slightly.  Also check that your foam fits into the end of the cylinder.
4. Save “complete foam guide 4 (param)” as a mesh, import it into your slicer of choice, and print it.  After printing a single one, join it to the “complete foam and drill guide 4 (param)” you printed as step 3 using some short M5 screws.  Test insert your foam.  If it works, you can print more pieces to get up to your desired length.

Some Parts:

Solid Pool Noodles(they are not always super consistent with their diameter, but they are wider than the 2.5" template with some margin):  https://www.amazon.com/gp/product/B098TS78S5

36" long, 3/8" dia drill bit:  https://www.amazon.com/dp/B00LLHES90