Centering a hole in balsa transition

[mccoy300]

I’m beating my head against the wall. I’m sure there is a simple way to accomplish this, and I know I’m overthinking it. I have a balsa bt-60 to bt-80 transition that is solid. Plan is to drill a one inch hole through the center, but I’m not sure of the best way to mark exact center, and I don’t trust my eyeball. Also unsure of how to clamp the transition without damaging it. Anyone ever ventured such an undertaking?

 

[GlenP]

Print up a centering ring template from payloadbay.com with the ID of the hole you want to drill and one each with the OD of the two ends of the transition.

 

[mccoy300]

Print up a centering ring template from payloadbay.com with the ID of the hole you want to drill and one each with the OD of the two ends of the transition.

You sir, win the internet today. Thank you

 

[jqavins]

What tools do you plan to use? There are many ways to skin this particular cat.

• Freehand?
  • GlenP's method sounds sound. When he says to make two templates, one for each end of the coupler, I guess that implies going in about half way from each end. That way, if the holes are a little bit off axis, the overall hole gets a bend in the middle and is centered at the ends.
  • Or use a center finder. Still good to go half way in from each end.
    
  • Or 3D print a self-centering center punch, a cup that fits the shoulder OD and has a spike in the middle. Put the cup on the shoulder and push it down to make a well centered dent. Only good for balsa, but balsa's what you've got.
    
    Again, make two and go in from both ends.
    • No 3D printer? Take a piece of body tube and a bulkhead that comes center drilled, or at least marked, from a vendor; glue it into the tube to make the cup. Put a snug fitting nail through the bulkhead, point in of course, so that the cup holds the nail centered. Tap the tail head with a hammer. And this works with harder materials, too.
• Lathe? Use a piece of body tube cut to the same length as the larger shoulder to protect it, then put that in the chuck and drill as you would anything else.
• Drill press? Clamp a piece of scrap to the table. Drill a hole the same diameter as either shoulder. (I'd prefer the larger end, but it's probably not important, so if you've a better drill size match for the small end go for it.) Without moving table or head, change the bit to the one you want, put the coupler into the hole in the scrap, and make your hole.
• Some other tool? I'm sure we can come up with something.

 

[BigMacDaddy]

Can you just print a template on paper, cut it out, line up with the face of transition, and put a pin through the center to mark the wood (or drill through paper into wood). I guess you need a drill press to stay vertical.

If you have a 3D printer just 3D print a new transition with the mounts / holes you want.

 

[mccoy300]

This is what I did, made a template for each side and drilled half. Balsa is super grabby which I didn’t expect, and it clogged the forstner but I made it through. I still need to clean the hole, but mission mostly accomplished. In retrospect, I would have built a jig, or soaked the balsa in thin CA first as I think that would have helped. Thank you everyone for the help