What's your approach to cutting balsa and ply for kit builds

[toto]

What's your approach to cutting balsa and ply for accurate fitting when building kits from sheet and stick materials?

 

Even when thinking clever and allowing for blade thicknesses etc, it can still be that you end up with a less than perfect fit.

 

I have a couple of kit pack builds for later and decided the best approach is to cut slightly oversize and then sand back to a comfort fit.

I've just added a proxxon sander to my armoury. I have a few of their tools and find them very good at what they do.

 

Toto

[John Lee]

Measure twice and cut once!

[Martin Harris - Moderator]

Some info on how I go about it in this thread (click the top of the box below to go to the relevant part of the thread):

 

 

[john stones 1 - Moderator]

Good tools make it easier, sharp blade in your scalpel is a must, some parts can be cut spot on without sanding others not so easy, belt/disc sander and good selection of Permagrit tools you're good to go.

When you're relatively new to model building you can feel every MM is a big deal, it often isn't. Accuracy improves as you build more, same with your flying.

[Nigel R]

1 hour ago, toto said:

What's your approach to cutting balsa and ply for accurate fitting when building kits from sheet and stick materials?

 

Low tech, keep it simple: knife, steel rule, sanding block.

 

Transferring shapes to wood, accurate cuts, accurate sanding, all learned skills. As john says you get better the more you build.

 

 

1 hour ago, toto said:

Even when thinking clever and allowing for blade thicknesses etc, it can still be that you end up with a less than perfect fit.

 

You are way overthinking this.

 

[Martin Harris - Moderator]

Many plans contain minor dimensional errors due to drafting errors and print process distortion and the thickness of the printed lines precludes accurate cutting to blade widths - in fact knife blades don't actually remove any material anyway!

[Flying Squirrel]

Grain direction can also play a part both in cutting/sanding and adding strength to a model

[Martin Harris - Moderator]

Very important IMO.  A good plan will indicate the correct orientation but still think about it while you're cutting out.

[toto]

All good advice I'm sure. I'm an advocate of good tools and where possible, the right tool for the job. Sharp blades .... goes without saying it's interesting though that plans can lose their scale as they transition from electronic to hard copy etc but on most of these models, maybe a mm or so is not the end of the world. A bit of build to suit I'd imagine.

 

Toto

[leccyflyer]

For transferring shapes and dimensions from plan to wood, I used to be an advocate of Pete Nicholson's Model Design philosophy of using a copy of the plan, temporarily glued to the wood with a Pritt stick, which was then cut out accurately with a good sharp scalpel, or sharp Stanley knife for liteply or thin birch play. The technique is also useful for thicker ply, using a scroll saw.

 

On recent builds I have traced over the parts on the plan, using Frisk film, then put that to the wood, allowing easy transfer of the dimensions to the wood - cut out being by the same good sharp tools. Any small inaccuracy built in - such as by the thickness of a pencil line, really isn't going to be critical.

[Eric Robson]

When notching ribs etc  I use a razor saw for cutting across the grain. 

[Mike T]

Swann-Morton 20-series blades in a No 4 handle.  Stanley and/or snap-off blades for the heavy stuff.  Japanese pull-saw (24+ tpi) for liteply and cross-cuts.  Permagrit block for bringing down to size, used on its side with a bench hook.

 

Always start with the elevators and/or rudder to get your hand and eye in.  By the time you've finished everything else, you'll look at them again and decide you could have done better! 🙂

[Geoff S]

1 hour ago, leccyflyer said:

For transferring shapes and dimensions from plan to wood, I used to be an advocate of Pete Nicholson's Model Design philosophy of using a copy of the plan, temporarily glued to the wood with a Pritt stick, which was then cut out accurately with a good sharp scalpel, or sharp Stanley knife for liteply or thin birch play. The technique is also useful for thicker ply, using a scroll saw.

 

On recent builds I have traced over the parts on the plan, using Frisk film, then put that to the wood, allowing easy transfer of the dimensions to the wood - cut out being by the same good sharp tools. Any small inaccuracy built in - such as by the thickness of a pencil line, really isn't going to be critical.

 

If you're lucky enough to have PDF copy of the drawing (and Peter Miller is very generous in this respect) you can easily print selected parts of the drawing and stick them to the balsa sheet for cutting out.  If it's a parallel wing with similarly shaped and sized ribs then cut out (say) an aluminium or thicker plywood pattern and use it to cut out the ribs individually with a scalpel (I favour 10a blades just about exclusively).

 

Of course you can buy at relatively modest cost sets of ribs ready cut for many of the more popular designs. iGull on eBay has a huge number available for example.

[Paul De Tourtoulon]

I have in the past photocopied bits, then used the copy and an iron to transfer the ink to the balsa.

I hand sand everything, good tools and files for adjusting the cut-outs are essential.

[leccyflyer]

Geoff - that's what I do for ribs, cut a ply template - derived by sticking a copy of the rib shape from the plan onto the ply, then use that to cut the ribs individually, if there's not too many, or a pair to use the sandwich method. Spar slots are cut using the Permagrit spar slotter.

[David Davis 2]

To transfer patterns to wood I use carbon paper under the plan. Not as accurate as photocopying the plan I'll agree but it works and all of the models I have built using this process have flown.

[toto]

Loads of ideas being flushed out here. Great stuff.

 

Toto

[Nigel R]

Some bedtime reading

 

https://rclibrary.co.uk/title_details.asp?ID=2672

[toto]

Cheers,

 

I'll get it downloaded and have a read.

 

toto

[Don Fry]

A very successful rich ex builder mate explained.

“Don, the customer does not actually see the process, they see the result. it looks straight, square, tidy, does not fall down.” Much the same as a tidy build. The frame is rough, but gets more attention at the end. 

[toto]

My proxxon sander arrived as well. 

 

 

A great addition to the work bench ...... Once I clear it a bit ........

 

 

foam cutter which is a great tool as well.

 

 

small bench circular saw.

 

 

and a pillar drill.

 

what more could you need 😄

 

the shed does need tidied in that corner but there is still some remodeling of the shed to be done for model storage space so I will get around to that. The good thing is all these machines are small and portable so can be moved around as needed.

 

great stuff

 

toto

 

[toto]

Just had a closer look at my bedtime reading as supplied by Nigel R. I've only really started on it but what a great read. Some clear instruction and illustrations. ....Thank Nigel.

 

Toto

[Paul De Tourtoulon]

All tooled up, so is there any room left to build ?.😄

[toto]

Hi Paul,

 

Not a lot at the moment but I still have things to move out yet so there will be more space created. I have a work bench area that I use when laying out stuff for the ARTF assemblies which will be freed up when I start on the kits and there will be a table I can put up for the winter which will remain up permanently. 

 

I must admit though, I need to be careful now as the shed is getting pretty full. The new shed will not be until well into next year.

 

Toto

[Rich Griff]

What more does one need ?

 

A bigger shed perhaps 😁