|Jonathan M||10/02/2019 11:20:22|
669 forum posts
Need to order a complete supply of sheet and strip balsa for my first short kit, a 2m slope-soarer, which has been designed and laser-cut in exact Metric. Some stuff can be the usual Imperial equivalent (e.g. wing sheeting can be 1/16" rather than the exact 1.5, etc) but some needs to be spot on to match laser-cut parts (e.g. 2mm, 5mm, 10mm).
Is there a UK supplier that does the Full French - including the ability to choose light/medium/hard densities?
447 forum posts
I was told by a leading balsa supplier (around 1990), that balsa supplied in the UK IS cut to metric dimensions.
|Martin Dance 1||10/02/2019 12:16:37|
|194 forum posts|
SLEC certainly advertise and supply metric sized balsa it's in 1 metre long pieces. I believe Balsa Cabin do the same thing. Metric sized balsa is also available from Mantua models based in Windsor.
I'm not sure about SLEC cutting all balsa to metric sizes but certainly their 4 inch wide sheet is 100mm wide as I discovered recently.
|Stuart C||10/02/2019 13:16:46|
|121 forum posts|
All the 2mm sheet that I buy is always oversize by 0.38mm !
|David Davis||10/02/2019 13:43:29|
3349 forum posts
I have recently built this fuselage for a Baron which I plan to fly in a competition in September. The longerons are from 1/4" square basswood and the uprights and cross pieces are from 1/4 sq balsa, bought from SLEC. The front fuselage sheeting was bought from a French supplier. It purports to be 6mm thick balsa sheet but it proved to be rather thicker than the basswood and had to be sanded down to match.
Edited By David Davis on 10/02/2019 13:44:13
|Martin Harris||10/02/2019 13:47:03|
8672 forum posts
Could you speak to the short kit supplier and enquire where they sourced the material it was cut from? You won't get a better match!
|David Davis||10/02/2019 14:17:47|
3349 forum posts
SLEC should be able to help you. **LINK**
|Andrew Ray||10/02/2019 14:50:00|
699 forum posts
Balsa wood is an organic material and is not (cannot) be machined to such tolerances. It also changes with humidity and adjustments will have to be made during the construction process. It is what it is.
Isn’t wood from a timber yard supplied in nominal sizes because of the natural variation in the wood?
Edited By Andrew Ray on 10/02/2019 14:52:57
|Trevor Crook||10/02/2019 17:09:12|
|824 forum posts|
Mantua Models in Windsor supply both balsa and piano wire in metric sizes. The latter is particularly useful for replacing the bendy stuff used with some ARTF retracts.
|Geoff Sleath||10/02/2019 17:19:40|
3272 forum posts
I just wish Imperial units were done away with altogether. It's probably only the US that seem to be resolutely sticking to the 20th (or even 19th) century. I admit I have a few problem with some metric units (wing loading and bike frame sizes to mention 2) but that's because I'm old. I use almost exclusively metric threads and dimensions otherwise.
I had difficulty acquiring metric sized brass tubing when I made the Gordon Whitehead designed undercarriage for my DB Gypsy Moth.
Edited By Geoff Sleath on 10/02/2019 17:21:06
|Martin McIntosh||10/02/2019 18:10:38|
2874 forum posts
As far as I know all wood, whatever type it may be, is cut to imperial sizes in the UK because that is what the machines are set to. Timber generally comes in imperial lengths etc so if you want 2m from an eight foot plank then you pay for the eight feet. An 8x4 ft sheet is still 8x4 whatever the nearest metric equivalent may be.
When I built my modelling shed some years ago I wrongly assumed that everything must by then have been metric. Put the hardboard battens at 1m only to discover that white faced board was still 6x2.
Can be frustrating when building a model from a plan because the CAD drawing is invariably in metric now but the balsa is not. It can often make a very big difference.
|Jonathan M||10/02/2019 19:54:04|
669 forum posts
Thanks guys. I'm happy working with both systems, and the problem only arises in certain cases such as this one.
In my day-job I sometimes work with hardwood to plans which are always done in Metric. So if I need an oak component to be exactly 25mm thick, then I buy 1-1/4" or 1-1/2" rough-sawn, which is almost always about 1/8" thicker (whether by law or by custom I'm not sure?) than its nominal size - and the board will always be to varying degrees bowed, cupped and in wind (twisted). Then I machine the board down, usually in two stages: the first after roughing out the component oversize to allow it 'stretch' and settle for a few days after being released from its long captivity inside a dried longitudinal slice of tree, then to final thickness plus a smidgeon to allow for hand-planing, scraping and sanding.
But in the case of this short-kit (from a French designer based Ireland as it happens, with international carriage and a lousy exchange rate) which has laser-cut ply and balsa components notched out for exact thicknesses (e.g. wing-spars, inner leading edges, etc), I have no suitable kit to machine balsa - the 3-phase thicknesser would make mincemeat out of a soft and floppy sheet! The choice then is either to find a supplier of exact metric thicknesses in the densities I'd prefer, or buy Imperial in the next size up (from Balsa Cabin or SLEC who both enable choice of density), then thin down components by hand or using a router-jig. But this would be tedious and inefficient, and would begin to make my hobby resemble my day-job! Or just bodge it... which would probably suffice but would annoy me!
|Don Fry||10/02/2019 20:13:03|
3728 forum posts
Do you honestly think you will get exact metric, or indeed imperial. If you are that fussy, cut it yourself, or sand it yourself.
Not sarcastic. I live in France. The stuff I buy in France is no more metric than the stuff I buy from SLEC is imperial.
|Andy Hall||10/02/2019 20:24:30|
10 forum posts
|Manufacturing tolerances are going play a big part in all this.|
Either way, only 47 days 'til we revert to feet, inches, pounds and onces !! 😂
|Don Fry||10/02/2019 20:49:14|
3728 forum posts
Or keep moving to world standards.
|Andy Hall||10/02/2019 21:18:38|
10 forum posts
|Piers Bowlan||11/02/2019 05:45:23|
1804 forum posts
Andy, you need a balsa stripper. Just buy a 1/4in sheet and set the stripper to 5/8th in. You can plane it down to the correct profile on the upper surface of the wing or sand it if you don't have a razor plane (get some spare blades too). Talking of sanding, get a permagrit sanding block if you don't have one (expensive but you will never need to buy sandpaper again!)
What is the model by the way?
Edited By Piers Bowlan on 11/02/2019 06:04:00
|Percy Verance||11/02/2019 06:59:45|
8109 forum posts
Or you could go all out and treat yourself to one of these......
Once I do switch it on I don't just cut one strip, I cut 20 or 30 of the sizes used most ie: 1/4 square. Suddenly, all those harder sheets that nobody wants in your local model shop, become sought after ........ plus you save a packet over paying for pre-cut stuff. I tried one of those stripper gadgets with a blade in, but they struggle with harder grades of balsa like you'd choose for wing spars. The Proxxon simply glides through it with superb accuracy......
Edited By Percy Verance on 11/02/2019 07:00:29
|SR 71||11/02/2019 09:13:41|
276 forum posts
|I have one of those Percy very useful little saw|
But I have had the magic puff of white smoke from mine
Still trying to find a replacement part
|Nigel R||11/02/2019 09:46:37|
2933 forum posts
I concur with the above opinions, balsa is only ever approximately the size you order. If you have slots in laser cut ribs and whatnot, which need other stuff slotted in, I would suggest making yourself a slot sander and just opening up the slots a bit. Permagrit will sell you an expensive one, but I've only ever cut short (maybe 6" at most) strips of paper and stuck them to bits of hard scrap balsa the right width. Then trim the paper if it overhangs.
One of the great things about balsa is that it is so soft you can knock up all sorts of sanding widgets in no time at all, to get repeatable angles and bevels and slots and whatnot.
Edited By Nigel R on 11/02/2019 09:50:19
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