using CAD to own design

[ben goodfellow 1]

has any one had any experience with using cad to design and produce your own planes i found a really good buid blog and would love to try it .if you have whats the best program to use and the best place to start.

[Ady Hayward]

Hi Ben,

I use an application by Alibre: Alibre Personal edition. It is a full 2d/3d Cad application and can save the files in the main types DXF and DWG so it can share between other CAD apps. I started by copying my plans that were on paper then worked up to drawing from scratch all in 2d, and now getting to grips with 3d. Many start by learning the 3d side of it which can automatically produce the 2d drawings from the 3d model. There are many CAD apps out there so where possible have a try out first before opening the wallet.

Ady

[Stephen Jones]

Hi ,

I paid £9.99 for Turbo Cad 14 Deluxe from one of those revolving racks they have at Pc World .

i have had it for some time but until recently never tried it as i find it easier to use paper and pencils

And having just started to use it i think i am finally getting to grips with it but it will be a long learning curve for sure .

I also have draftsight free cad but no longer runs on my Linux system . so not really got to grips with that , but seems very useable software .

[ben goodfellow 1]

i will have a look at the two of them, i seen a blog about someone designing then getting his bit laser cut , well my friend has a laser cutter so i might beable to beg him if i ever get to grips with any of the programmes and get something knocked up , thanks

[Stephen Jones]

Oh ,

i forgot to mention DevCad.com

[Lindsay Todd]

I use autocad, but there are plenty of others and most support dwg and dxf which are the most common file output formats to transfer to cnc cutters. I usually send dwg format files it also helps the cutters if you cluster the parts and make sure you don't have line duplications as this either takes time to edit out or effectively costs you money as the laser or mill re cuts the same line more than once. I also try and find out the timber sheet sizes used and use these as a border to cluster the parts. Basically the more I can do to make the cnc cutters job easier the cheaper it becomes. hope that helps a bit.

Linds

[ben goodfellow 1]

ok thats turbo cad 15 ordered , next question , if you want to say design a f16 jet is it poss to import a 3 view drawing and work away from that or to you have to do it totaly from scratch,

[GrahamC]

Yes you can do that. Normally you bring in a jpeg file and trace it in cad. I use Draftsight, a very powerful free package produced by Dassalt Systems. Well worth a look.

I also use doublecad free edition because its very good a printing tiled versions of large drawings.

[Lindsay Todd]

Wintopo is another free download that will alow you to import a jpeg and export as a dxf

[ben goodfellow 1]

well got the auto cad today , the book is a shade baffling. going to take a bit to get to grips with it any tips or tricks greatly taken

[Robin Kearney]

Lindsay, quick question for you regarding getting parts laser or cnc cut. Do you have to make allowances for the cutter in your cad drawings?

r.

[Richie Carey Maddog Designs UK]

Ben the best advice I can offer is to go on to youtube and have a look at the many auto cad tutorials, in my opinion it is so much easier and quicker than using a book.
Robin my laser cutter is set up to cut hair line which gives such a fine cut there is no need to make allowances, hope this helps.
Richie

[Lindsay Todd]

Hi Robin,

As Richie say's you do not need to allow any tolerance for the cutter, the line is I would guess typically less than 0.25mm. I do leave the tagging of the parts to the cutter, these are the small connections to the raw material that stop everything falling out and are trimed off when you remove the parts from the sheet.

As for learning CAD like most things practice, practice, practice. You tube does have some good tutorials but also remember their are many ways to perform tasks. I think autocad has about thirty ways of just drawing a line. So don't be afraid to go you own path if it seems the logical way to you and achieves the correct end result.

Linds

[Peter Miller]

I need to see the drawing full size when I am designing. It is surprising how different something can look when enlarged. Loook at some of the vinateg designs that look nice at their original small size and look horrible when scaled up. Vic Smeed's Coquette is a good example

. IT is also amazing how a subtle change in a line or angle can make or ruin a shape. and this can't be seen on a small screen. Of course these are just my own feelings/preferences.

I do use compufoil these days to design the wings as it saves so much work with tapered wings and elliptical shapes

[Danny Fenton]

Hi Ben, you are in for a very time consuming process, but it is good fun.

I am not as talented at CAD as the other posters, and have never gone beyond 2D but use TurboCad.

It is a wonderful tool

Peter, I use a 24" monitor as I like to see it at a good size too

Cheers

Danny

[Robin Kearney]

Lindsay and Richie - thanks for the advice.

Danny you had me lol with that comment - I was waiting for somebody to suggest Peter bought a bigger monitor

[Peter Miller]

Still not as big as my AO size drawing board on a stand .

These days they are so cheap. Mine cost 2 ounces of tobacco and that was about 22 years ago.

[Lindsay Todd]

Peter, your absolutely right about seeing a design full size, I guess you do become familiar to some extent (especially with a 24" monitor) but their is nothing like seeing a full size plan to realise what a load of old garbage you have just created. I speak from experience. You get better eventually I am told. I bitterley regret getting rid of my A0 table, I just ran out of space and something had to go.

Linds

[Erfolg]

Other than for personal preference of a modeller I can not see many reasons to use CAD.

The one advantage is that the files from a cad drawing can be used for laser cutting.

For commercial applications, the advantages are not the same as for modellers.

Typically the files can be amended as modifications are needed, such as when a mistake has ben made. Other reasons are that the files can be used as the basis for another similar design. The files in some instances are used in modelling, for such purposes as heat transfer, stress analysis, fluid flow analysis etc.

Although great claims were made that CAD drawings were quicker to produce than using drawing boards. It was quickly established that CAD drawings were no faster to produce, often taking longer, even using the best CAD operatives. The savings coming from ease of amendment at a later date.Plus the cost of drawing storage was drastically reduced. Plus benefits from modelling and evaluation processes. A final advantage is that files can be shared and sent to distant locations, quicklt and at low cost.

I have two CAD systems on my PC, I have used them twice, once for my own extension drawings, the other for my daughter. The reason being very much along the lines as commercial applications. Allowing many variations to be discussed with wife and daughter. Then amendments during the Planning and building regulation phase. Later parts extracted for application to vary the original approved drawings. Non of this is relevant for the hobbyist.

I do design my own models, or modify other peoples original design. What do I use? Not my Ao drawing board, as I build on that. No, my kitchen table, on wall lining paper, using a HB pencil and rubber. These are not engineering drawings, where 2-4h pencils are needed, sanded to a chisel point, where absolute accuracy is sort.

Another major disadvantage of CAD files, is that my local printer charges over £20 per plotted sheet. Which can then be used for multiple prints such as commercial Architects and Engineers need for tendering, approval and manufacturing purposes.

If you are setting up a model manufacturing business, CAD type systems will almost certainly have a place.

But if you think CAD drawing is fun, great.

ME, I enjoy a few sweeps of a pencil, the use of French curves, rubbing out, sketching in. No tapping away at a keyboard, starring at a screen. The joy of looking out of the window, as I ponder, what if I............

[kc]

Well I have to agree with Erfolg ( that may be the first time! ) Drawing with pencil & paper is more enjoyable than using CAD. Use CAD if you like or if you want to use it in your career, but for speed, economy and enjoyment use a pencil and lining paper ( wallpaper shop ). Make a drawing board from ply 6ft by 3ft and use a Tee square along the top edge ( not the traditional way ) as most lines are vertical with maybe just one horizontal datum line. A couple of set squares and a few French curves and maybe one of those circle guides from Helix is all you need.

If you need to scale up a plan from a magazine drawing then a calculator with a constant is very handy ( less than a pound now )Simply measure all the dimensions from a datum line - probably the thrustline and the fin rudder hinge line - and multiply by the same factor to get full size. You may want to use the basic dimensions from a proven design and re-style it to your own design - at least you can be pretty sure it will fly reasonably well.

I find it worthwhile to do all the fomers and small parts on A4 paper so that when finished they can simply be photocopied on a printer/scanner/copier to produce an extra  copy to stick on the wood.  Cut right through the paper into balso or ply with a scalpel to produce a scored line in the material.   Then saw as needed.

Edited By kc on 10/01/2013 15:07:07

[coline]

Greetings Ben, interesting to read your post concerning CAD systems for own design modelling.Your choice of Turbocad 14 is well made. I run TC 15 and can vouch for its versatility,it is very very good, You have a fast 3D solid modeller with with all the attributes of some proffessional systems. The turbocad proffessional systems are expensive but the deluxe versions are still about 90quid. I base my comparisons on 15 years using an Intergraph system finishing in 1994 and my advice to you is keep plugging away at it, Use the help feature and the user guide booklet and you will be well pleased. Regards Coline.

[ben goodfellow 1]

i am a time served fabricator and therefore well versed in engineering drawings i can manually draw plans absolutely no probs , this cad is a feather in the hat for me if i ever get my head round it(which i will) am going to check out some you tube tuts tonight, then save up and buy a laser cutter and get it delivered when shes out and not tell her

[ben goodfellow 1]

my friend has a laser cutter and really its so amazing to watch it working .

[Erfolg]

Ben

I would think that for the average aeromodeller it is being able to compile files for laser cutting that makes CAD a consideration.

I take it you tack all your components before running a full penetration glue fillet? On critical work do you dye pentrant test, or go for Gamma graphs or Ultra-sonic?

[ben goodfellow 1]

used them all macro, dye, bommbing ,mag part as i am also a coded welder. two friends of mine are cswip testers one off shore one for doosan  yhey know more on them than i do ,, but they cant weld though.

Edited By ben goodfellow 1 on 10/01/2013 18:29:46