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The Ohmen

My first electric powered aerobatic model

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EarlyBird23/11/2020 20:16:01
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646 forum posts
460 photos

I have just ordered The Ohmen and if you are taking orders then one of each please.

Cheers beer

Steve

RedBaron23/11/2020 20:25:09
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67 forum posts
33 photos

Bother I posted that without completing the thought:

templatessetup.jpg

The first step was to scan key parts of the plan,. import the scans into the 3D program and set them up as shown above.

It is then relatively easy to construct drawings and then to make the solid parts within the program. The parts are then exported as .stl files to ones PC desktop or anywhere.

The .stl files then need to be processed in another program to produce the toolpaths for the 3D printer and there you are.

I have been playing at 3D design for a couple of years but this cowling was the first project in a new design program (purchased)

Does it cost a lot well yes and no. Where I have got to after a few iterations is:

The free plan thank you Peter.

The design program, there are lots of free ones but many are not up to the job, the one I have just acquired was wincingly expensive but less than the cost of a middling moulded glider

The program that makes the tool paths, there are lots of free ones but I have settled on a purchased one I think it was about £50

The printer, there are lots of cheap ones but I have now settled on one that cost much as a medium sized electric model. Do not buy one that locks you into the manufactures consumables! For filament choose an established supplier and buy a medium to higher range filament, cheap filament will not do.

So the whole lot cost a biggish moulded glider.

I do enjoy making stuff in wood. But... Once you have designed say a servo mount it is very easy to modify it for another type of servo or another model. The same if you make a mistake. So I believe that embracing the new technology helps one to be a more efficient builder and it is a different sort of fun

On the more mundane side of things stuff around the house often breaks and the plastic parts are completely unobtainable now I can design and print replacement parts in a lot of cases.

Peter Miller23/11/2020 21:03:00
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11780 forum posts
1416 photos
10 articles

Amazing. I am lost at the complexities.

I do have a Dremel 3D printer. A freebie from Amazon Vine. About all that I have managed is a few pilot figures from it...So glad that I didn't have to pay for it because they would have been the most expensive pilots in the world!!

Sounds like you have your first customer!!!

Edited By Peter Miller on 23/11/2020 21:03:48

RedBaron23/11/2020 23:19:37
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67 forum posts
33 photos

If I may say so - not complex, just a load of simple sequential actions.

If you have a printer all you need is practice, decide on some simple projects like design and print a servo mount to go in the Ohmen? and when that works another project. But from my own experience regular use is good

The more you do the more you can do.

Ron Gray24/11/2020 06:48:04
2533 forum posts
1013 photos

Interesting RB, which program are you using, I use Fusion 360 which I find is incredibly powerful plus has lots of YouTube vids explaining how to do things but am always interested in other software.

RedBaron24/11/2020 10:01:32
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67 forum posts
33 photos

I too have been using Fusion360 and very good it is but I have recently changed to Rhinoceros.

It is always a struggle changing to a new UI. The Cowling was my first Rhino project.

Piers Bowlan24/11/2020 10:14:56
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2351 forum posts
68 photos

Huge respect Red Baron, very impressed. yes

Why don't you submit an article for inclusion in RCM&E as 3D printing has become so popular and has not featured very much in the magazine. I tried a beta version of Rhino on my Mac with a few exercises but found it very challenging. Perhaps I should have persevered.

Nigel R24/11/2020 11:22:08
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4428 forum posts
717 photos

Nice work RB. yes

RedBaron24/11/2020 19:48:51
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67 forum posts
33 photos

This last post has nothing to do with The Ohmen, it is more to encourage people with printers to use them more and those without to get a basic one. After this Peter I promise to stick to the subject and thank you for your patience.

I mentioned above about non modelling uses, such as replacing broken and irreplaceable household items. Well I should not have tempted fate. For about twenty years we have had two wooden geese (carved from bamboo root I think) that live in the garden next to the bird bath.

This afternoon I went into the garden for some fresh air and noticed one of the geese lying on his side. I went over to stand him up and found to my horror that both of his feet had completely rotted way - no wonder he was lying down.

Well it seemed to me that rotten feet qualified as irreplaceable. So after 15 minutes of designing and about 1.5 hours printing Mr Goose had a new pair of orange feet. Imagine doing that by carving lumps of hard wood.

ducksfeet.jpg

RedBaron25/11/2020 18:36:03
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67 forum posts
33 photos

Further to the comments about Fusion360 above. I decided today to start exporting my designs from Fusion360.

And........

There is no way to export designs AND drawings from Fusion360 unless you have one of their paid for options. In fact the drawings and associations to the solids are in the wind. If you are a Personal Use Only user then you are locked into a proprietary format with no escape for your work!!

I have no desire to be locked into any product or format which makes me very happy to have recently chosen Rhino

I can export the Fusion360 solids via STEP format, which I will do but I will not have the associated drawings!! For most designs this isn't too bad. Then I will close down my Fusion360 account.But a major swindles as I do nor remember being told this at the beginning.

RedBaron06/12/2020 18:33:35
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67 forum posts
33 photos

Back to the Ohmen - my build is complete except for a short list of minor things to do before covering.

Top of the list today was the matter of the windscreens, no matter how hard I looked there was not a template on the plan. Now whilst one can make guesses and after endless trimming with fine scissors arrive at a good result I much prefer to start with an accurate template.

My method today.took longer than the old fashioned approach but it was an investment in understanding what Rhino can do.

See the pictures:

1 I constructed a model in Rhino of the upper body and front windscreen from careful measurement of the plan.

2 Show a pretty neat feature of the program - one can unroll a surface to create a template! This picture shows the curved screen and flat template

3 I tried to upload a jpg of the template such that it can be printed and the template cut out. I have cut out the original image on thin card and offered it to the fuselage and it looks almost OK The unrolling process was not quite perfect and I don't know why yet. However I think the image is useable.

I cannot guess whether or not the uploaded image preserves the actual size. If anyone tries to use it and the size is wrong, then just scale uniformly so that the distance between the two pointed tips is 125mm

ohmen-upperfusandscreen.jpg

ohmenscreenandtemplate.jpg

ohmenscreentemplate.jpg

Peter Miller06/12/2020 19:32:15
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11780 forum posts
1416 photos
10 articles

Hi Red Baron.

Sorry! No templates. I just cut mine until it looked about right. Thex good old TLAR

The thing is that if one looks at pictiures of similar aircraft they all have variations frpm the simple curved shape to fancy one with metal frames. I have even seen a fullsize Tiger Moth with both types fitted.

Then one can even do really fancy ones like my Destiny.

destiny eng 003.jpg

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