Cutting big holes in balsa

[Spikey]

If you needed to cut getting on for 20 identical holes of around 38mm diameter in 1/16" sheet balsa, how would you do it without driving yourself up the wall?

[IanN]

You could find a piece of suitably sized metal tube and sharpen the edges

[Former Member]

[This posting has been removed]

[Stevo]

Router / Dremel...

Cut a template, try it out on some scrap first!!

[Guest]

I use Ian's tube method by sharpening the tube so that the bevel is on the inside to give a sharp cut on the outside

[Stevo]

Oh yes - Hence the Gaskin cutters...

**LINK**

 

I use these on Balsa and liteply..

Forstner Bits

Edited By Pete B - Moderator on 20/07/2013 21:37:47

[PatMc]

A cheap hole saw set from Aldi or Lidl.

[David Tweddle]

For the price this may be worth a go.

all the best David

[Spikey]

Cheers, chaps. I'll try a few different methods and see how I get on ...

[Stevo]

Beware, the hole saws produce an adequate hole in chipboard, but will tear balsa. One other way would be to cut them undersize with a scalpel, then...

Take a bit of wastepipe (36mm) and glue some 240grit around it. Gently rotate this pipe through the hole and it should round it off - to get up to size, wrap and glue some more paper around it to 38mm.

If it were me, I would go the router/dremel route, making an accurate hole to 38mm first, then rout through it, a 3-4mm SHARP bit will do that quite nicely.

[Mowerman]

When I built my first Femto Fun 400 (see my album) the lightening holes (2x35mm 1x 24mm 1x13mm) in the 10 ribs were cut using a compass cutter, took ages and resulted in sore fingers. for the second build I invested in a set of Brian Gaskin's 'Softbore' hole cutters- easier, neater and much quicker.

[Myron Beaumont]

Cut one hole out after marking it out (lots of ways of doing it) with a modelling knife ,then use the disc to cut round wherever you need more holes.I sometimes wonder why some people take up modelling when all they do is search for a tool to do anything and everything.

It has just taken me about 30 seconds to cut a hole in 1/16 hard balsa

Myron YO13 Enjoyable modelling by hand dept.

[Glyn R]

I use a holesaw in a drillstand. Use a backing board helps to reduce tearing. If the saw is sharp and you do not try to rush it works fine. I use a set of saws just like David Tweddle's post.

Edited By Glyn R on 21/07/2013 18:49:34

[Tom Sharp]

I buy a packet of holes and stick them on to the balsa. Job done.

[Spikey]

Posted by Tom Sharp on 21/07/2013 21:44:20:

I buy a packet of holes and stick them on to the balsa. Job done.

Now why didn't I think of that?  What's the best glue to use - or can you get stickyback ones nowadays?

Edited By Spikey on 22/07/2013 07:06:06

[Jonnor]

Get a drawing compass....thingy with a spike and a hole for the pencil......inch or so of 6mm dowel. saw a slit in the end of the dowel, slide in a Swan Morton blade or similar and secure. Pop this in the compass and you've got a variable size balsa cutter. you can also use it for cutting circles in covering films.

[Martyn K]

 

If you make a compass cutter then you need one with an articulated leg so you can keep the blade vertical.

A bit like this

Martyn

Edited By Martyn K on 22/07/2013 22:28:38

[David Tweddle]

Posted by Glyn R on 21/07/2013 18:44:45:

I use a holesaw in a drillstand. Use a backing board helps to reduce tearing.

I would also have a backing board to centralise and already cut to a depth of 1/8" (3mm). Making sure the power is off at the wall and cut by rotating backwards by hand whilst maintaining light pressure.

Also these things are probably made of cheese so you could use a fine hacksaw blade ground to fit in the holder. They are hardened steel so health & safety equipment must be used (they can and will shatter) and common sense, also gentle heat...

David

[Greybeard]

If you have a pillar drill then a tile hole saw may work if used at a slow speed.

[Sparks]

I use a Rolson Tools Compass Cutter - Avaliable from most hardware/diy outlets.

Edited By Sparks on 23/07/2013 08:55:44

Edited By Sparks on 23/07/2013 08:56:12

[Mowerman]

The compass cutter shown above is simmilar to the one I used. Will do a good job but a bit slow and tedious if lots of holes required.

[Spikey]

OK ... I now have the answer, or at least a way that works for me.

When I built my Lazy Bee, I cut the portholes using Andy Clancy's design of home-made hole-cutter, but frankly it was a major PITA. So much so that I swore I'd find a better way of doing the job before I started Bee #2.

Seems I'm not the only one who didn't get on with the Clancy cutter. The dude who made this video didn't either, but he came up with a big improvement on it, which works a treat. It's well worth checking out if you need to cut big holes in thin sheet balsa. Shame he got so carried away with the cringe-making Walt Disney effects, but there you go ...

[Andy48]

Just how much weight do you save this way, and are there any better weight saving options. Eg, smaller more powerful servos, shorter servo leads, lighter wheels etc.

[Spikey]

Posted by Martin Phillips on 23/07/2013 15:15:00:

Just how much weight do you save this way

Dunno Martin, I don't own a balance which is sensitive enough to tell.  But in the case of the Lazy Bee, the holes are the portholes in the fuselage plus the same-sized holes in the tailplane, all of which are purely cosmetic.

Having said that, the Bee tends towards tail-heaviness so I guess the holes in the tailplane help in theory, even if they make no discernible difference in practice.

Edited By Spikey on 23/07/2013 18:08:49