How do you cut yours?

Hi

building from a plan, and cutting the balsa and ply in some instances, what is your preferred quick method of accurately cutting them out? I am after a cheap cost effective way of doing this, that means I am not going to be spending all my evenings cutting out parts

I suspect the requirements of 'quick' and 'accurate' could be mutually exclusive, or expensive. A laser cutter would give you both but cost effective? There is the investment in the machine probably several hundred pounds and the investment in time needed to learn how to program it and operate it. if you are looking at looking at the long term and a substantial number of models, great idea. If you are like me one or two models a year not so good. So its back to hand methods. Making large numbers of identical parts e.g. wing ribs, templates and sandwich method is probably the quickest and insures identical ribs, or identical to the templates. For formers etc in balsa my preferred method is photocopy on my printer then spray mount onto balsa and use a scalpel and steel rule for straight lines freehand for curves. I use a scroll saw for ply parts.

Apart from that an evening spent cutting is quite theraputic especially as the pile of parts grows!

Not sure how to put this, but cutting parts is kind of a big part of the woodwork in a wood airframe... just buy a laser cut plan pack if you want someone to take the problem of producing parts away.

Anyway, as to the first question; measure up, then, knife, steel rule, drill, coping saw, razor saw, various sanding blocks, a disc sander, a dremel sanding drum... depends on the part... I'm all manual and don't do high tech cutting like laser or cnc.

Photocopy on an A4 printer (if necessary roll the plan up like the ancients did -i roll in each hand to reach parts in the middle ) and then stick to wood using a few tiny - 1/2 inch- bits of double sided sellotape. Then cut right through the photocopy into the wood with a scalpel ( new model - new blade ) or a Stanley knife with new blade for thick balsa or thin ply.

Fretsaw or Jewellers saw ( piercing saw) for curved bits and ply. If you use a coping saw use the blade mounted to cut on the pull stroke just like a fretsaw. Straight cuts in Liteply can be done with multiple cuts of Stanley knife and straight edge. Straight parts of thick ply are best done by scoring through with scalpel then pencil in the groove and cut with a fine saw such as a japanese style pull saw.

Wing ribs can be cut by making a 1/32 ply template ( the offcut from the fuselage doublers ) cut with a stanley knife. Then  fix a tiny handle and use to cut each rib with a scalpel.   Work out best way to economise on balsa by seeing if you can interleave LE with TE, maybe inverting some ribs too.

Edited By kc on 24/11/2020 13:43:04

Thanks for the reply’s, really sounds like the two methods I was thinking would be the quickest, laser or scroll saw.

I have been doing this with no 10 scalpel and steel ruler, but some of the ply parts are going to be more tricky....have been looking for cheap scroll saw, but seems I miss out all the time at the moment...

I use the scanner / printer method as mentioned above, so easy and accurate. Handy for producing templates from the plan and then mounted on old cornflakes carton when carving / sanding fuselages or pretty much anything else.

Can't say I enjoy Cutting out parts - a labour of love at best and always glad when its done.

A set of Permagrits have been my best investment when it comes to modelling along with my bandsaw.

Scalpel, razor saw, power scroll saw.

It is part of modelling.

I can remember when Keil Kraft actually supplied band saw ribs in a Junior 60 kit. Absolute luxury!!! Mind you, the kit did cost about £3 for which you could buy a good engine.

Then we got Frog kits which even had die crushed parts. What a horrible mess they were!!!

Try cutting out the parts of an original KK Flying Scale Series Spitfire with a Blue Gillette razor blade snapped in half lengthwise and the one end snapped of diagonally. You haven't lived until you have done that!!!

One of the key things is to select the right plan first. Some modern CAD produced designs use intricate parts that are really too difficult to cut by hand - they are designed to be laser cut. Other plans including those drawn by hand are much easier to cut out as they use less intricate parts and straight lines where possible for formers etc.

Ah, the joy of photocopying a set of ribs and ironing the photocopy onto a sheet of balsa to transfer the image (before the days of home inkjet printers!) then cutting out the ribs only to find out they had been drawn inaccurately! Now it's a copy of the part made on the all-in-one printer and Prit stick it to the balsa. If it's a straight taper or parallel wing look into the sandwich method of rib cutting. Two ply or formica ribs for root and tip clamped either side of the correct number of balsa blanks and carve them as a block.

AS for those KK kits, the hours I must have spent gluing bits back onto the formers where they'd broken away, then more hours picking balsa cement off my fingers. Pure joy back then, now arthritis means hours of unlocking fingers and cursing loudly so I'd rather pay for short kits or ribsets off e-bay.

Instead of buying an electric fretsaw give the old hand fretsaw etc a try first but use a fretworkers Vee device - dead simple to make. See photos here on Tools you can make yourself

Also make traditional woodworkers Bench Hook or the improved type which uses a G clamp too in that thread. Holding the work firm is the key to easy yet accurate cutting.

That is what I do, make a thin ply template and cut round it with No 11 Swan Morton Blade onto the balsa sheet. Once I have made the rib template a set of ribs usually does not typically take more than an hour, if it is a parallel wing. A tapered wing obviously takes longer but once the ribs for one wing have been cut, I just carefully cut round them to produce the set for the other wing.

Blue Tack make an aerosol called Fast Tak which makes it easy to temporally attach the fuselage former images from the plan to your wood. Just cut round them and then peel off the paper.

For ply parts if you don't want to splash out on a scroll saw a cheap jig saw can produce good results, just use a fine tooth blade. If that is still too expensive the MacAlister one from B and Q is only £25!

Edited By Piers Bowlan on 24/11/2020 14:19:03

I photocopy the parts and stick them to the wood with print stick. As a bonus, that helps prevent thin balsa parts splitting. The glue comes off easily or with s damp sponge.

As for cutting;

A scalpel/No.11 blade for most balsa.

Razor blade for longerons and bracing strips

Scissors for thin ply

Stanley Knife for 1/32" to 1/8" ply

Razor saw for thicker ply, beech, thick balsa.

Most of the time if I need to make 1/4" or thicker ply formers I just laminate them from 1/8" sheet with PVA (or Epoxy if it's a firewall)

I use old tx antennae to make holes in balsa sheet

Lots of rat tail files.

A scroll saw is the best investment you can make. I am on my second one, this time a Jet from Axminster Tools, but if you can then get a version with a quick release blade and the ability to turn the blade by 90 deg. because the throat is only 16" meaning that you cannot slice a 36" piece of balsa down its full length with the version I have. It was £100 a few years ago. They sell blades at a very reasonable price as well. You need the Pegas 90.478C 25 tpi ones.

I use mine on all ply over 1/32nd and any balsa over 3/32nd thick in order to get a true vertical cut.

I too try to make a photocopy of parts if possible then cut round with scissors, pin to the wood and carefully draw round with a fine felt tip pen. Cut on this line and you will have an exact copy. Never paste the paper to the wood because it will expand considerably.

AH!!! Bob Cotsford remembers those KK kits!!! Chewing the glue off your fingers while watching TV. Oh Yes,

And then there was the never ending task of sharpening your Exacto blades on a sharpening stone, and following up with an Akansas Slip to produce a bladed as sharp as a scalpel. Some of my blades ended up at half their original length.

And then we used a hand drill to drill our holes. Power Drill??? In your dreams,Lad.

Now I go into my workshop with so many tools and life is so easy.

I like to print out the parts on A4 paper and stick them in place with a Pritt stick - the way that the original Model Designs short kits were done. Bear in mind if using a photocopier that they often are not 100% dimensionally correct - sometimes one axis is underscale relative to the other. Then cut out with a sharp scalpel blade or with the scroll saw if it's ply.

Trace through carbon paper onto thin card,cut the card shape out and draw round it onto the wood,templates can be kept for a rainy day or repairs after a sudden arrival

Jim

I have an ancient treadle operated Hobbies fretsaw - can be quite therapeutic. For some operations I'm lazy and use a bandsaw.

A note of caution if using a coping saw - the teeth are quite big and can easily cause damage if cutting thin materials.

Like Peter Miller, I remember well cutting out printed KK balsa parts with a broken razor blade. Never had the wherewithal to re-sharpen them and often had stains on the balsa created by red stuff leaking from one or other of my fingers.

Malcolm

When it comes to printing or photocopying I often find that the print is not quite to scale or slightly distorted. With various computer and printer combinations this can often be rectified simply by playing about with the printer settings. Usually the culprit is something like a default margin setting that can be turned off or changed. If one has a 3D drafted plan, things are much easier because one can print out the part outline with a background grid (e.g. 1-inch grid) and then check and adjust the settings rather easily to make sure that 1" really is exactly 1" in both directions.

I managed to get a scroll saw of Amazon, it was a refurbished model but it didn't have a mark on it when it arrived. I use the good reliable no 11 blade, razor saw,coping saw and a selection of sanding blocks etc. for most things and break out the power tools for the thick and hard bits. I find if you dont rush it and pop the radio on and enjoy the crafting of individual parts before you know it you have a full kit of bits. A good cutting mat and a vice help too!

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