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Old Jul 16, 2008, 02:46 PM
Tearing the Skies a new one...
Sensiblenick's Avatar
Sweden: Ystad
Joined Oct 2004
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Argh... you just fried my brain Jon.

This effectively cuts out the middle-process of making a plug.

Plugs are usually made because it is far easier to make the actual shape that you want, and then take a mould from it. Alternatively, making a female mould can take a HUGE amount of material if you're making - say - a mould for a car body. In that kind of case a male plug is the best option so that a female mould can be taken from it.

In this case however the moulds are relatively small, and I have scrap 7075-T6 (used to be called "aircraft grade") aluminium to hand that can be used... and this way I get moulds that are far more durable than fibreglass ones, and are "perfect" from the very start instead of potentially building in error from a mistake in the plug.
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Old Jul 16, 2008, 03:29 PM
hot air rises...
jfinch's Avatar
Pleasant Grove, UT
Joined Jul 2005
7,710 Posts
Those reasons are all very good, but what does Jon do when Jon drops the lower left wing mold off the table and into the leg of the chair? He cries and cries like a TV preacher is what he does. At least with a male plug it would relatively easy to make another female (I know, stating the obvious). But I do really like the "perfectness" of the female aluminium molds.

Jon
who now wishes his best buddy (tooling engineer with Boeing) was "into" RC planes...
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Old Jul 16, 2008, 03:45 PM
Tearing the Skies a new one...
Sensiblenick's Avatar
Sweden: Ystad
Joined Oct 2004
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All done for tonight...

You'll be wanting pictures then?

10:45pm. Time to go home I think.
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Old Jul 17, 2008, 01:32 AM
Tearing the Skies a new one...
Sensiblenick's Avatar
Sweden: Ystad
Joined Oct 2004
4,013 Posts
Recieved an E-mail from Dymond... Servos were shipped on the 7th of this month. I'd missed Andy's mail: it had been filtered as junk

So.. nice and relaxed postage times... hope they get here before monday!
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Old Jul 17, 2008, 04:43 AM
Engine? No, thanks.
Leonardo's Avatar
Firenze (Florence, Florenz, Florencia) Italy
Joined May 2005
557 Posts
too coooooooooooooooooool !!!!!!!!!!!!

5xstars
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Old Jul 17, 2008, 09:53 AM
You must die! I alone am best.
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Gee Nick - I hope it flies OK...
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Old Jul 17, 2008, 10:13 AM
Tearing the Skies a new one...
Sensiblenick's Avatar
Sweden: Ystad
Joined Oct 2004
4,013 Posts
Quote:
Originally Posted by slopetrashuk
Gee Nick - I hope it flies OK...
Yeah.. that's the rub with taking the time and effort to scratch-build things.. .. but with Peter W's input, I'm pretty sure it'll be fine

So.. how's your kit-Jart doing Andy?

EDIT: Nick bites his tongue as he realises that his own Jart is yet to fly....
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Old Jul 17, 2008, 10:23 AM
You must die! I alone am best.
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It rips...
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Old Jul 17, 2008, 11:07 AM
I want to believe...
winchdoc's Avatar
A hut in the woods in Oregon
Joined Jan 2003
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Nice Work!

.....(stumbling around the inter-web-nets)...
What's this thread? Oh, That guy from Sweden, Hasn't he finished that big Jarty-thing yet? What's this? CNC cut molds!?!?!

ZOMGWTFBBQ!!!

I'd be curious to know about your finish pass stepovers and depth of cut.
I may have to pick your brains if there are any good parts left after this project.

WinchDoc
Who likes shiny curvy surfaces....
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Old Jul 17, 2008, 11:11 AM
Tearing the Skies a new one...
Sensiblenick's Avatar
Sweden: Ystad
Joined Oct 2004
4,013 Posts
Step-over on the wings was 0.3mm using a 4mm diameter ball-end.
Some of the tailplane was done using a 0.2mm step-over... depth of cut I'm not sure about... Will have to find out from Jonas...

Jonas.. are you reading this?

Ellie's a hundred Km away today, and I'm sat once more polishing.. this time the Canopy mould =)
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Old Jul 17, 2008, 11:40 AM
Engine? No, thanks.
Leonardo's Avatar
Firenze (Florence, Florenz, Florencia) Italy
Joined May 2005
557 Posts
That's one of the coolest thing I've seen since my.... "first time I saw it".

PS: don't forget to put a generous amount of mold releasing wax, this time...

Cheers

Marco
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Old Jul 17, 2008, 11:55 AM
IforOneCareLessForThem
JonasC's Avatar
Sweden
Joined Jun 2008
5 Posts
Quote:
Originally Posted by Sensiblenick
Step-over on the wings was 0.3mm using a 4mm diameter ball-end.
Some of the tailplane was done using a 0.2mm step-over... depth of cut I'm not sure about... Will have to find out from Jonas...

Jonas.. are you reading this?
ia, just sat down to see your mirrorsurface polishing on that last part. No photos, so still rubbing it?

Anyways, the scallopheight and thus the stepover can be controlled by defining either (scallopheight or stepover). So the finnishing on theese parts where mostly specified with a scallopheight of 0.003-0.005mm.In some cases the stepover was defined to be for example 0.3 with a 4mm Ballend mill, which corresponds to roughly 0.0056mm scallopheight.

( Formula, if interested)

Depth of cut for the finnishing passes are harder to define explicitly, since it depends on the previous tooling. Generally i leave 0.1 mm for the finnish, but if the previous tool is to big to fit everywhere that might leave excess material. Same if you have a flat end mill in a curved area.

Hope that helps, JC
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Old Jul 17, 2008, 12:01 PM
Tearing the Skies a new one...
Sensiblenick's Avatar
Sweden: Ystad
Joined Oct 2004
4,013 Posts
Ladies and gents, This bloke ^^^^ is the genius behind the Programming.

Welcome to RCG jonas

Photos are... a few minutes away
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Old Jul 17, 2008, 12:18 PM
Tearing the Skies a new one...
Sensiblenick's Avatar
Sweden: Ystad
Joined Oct 2004
4,013 Posts
Here we are...

Last bit of machining 'til we down tools and head off on holiday. the rest are all small fast parts, and we'll be knocking them out next month.

I'm off to the UK for 3 weeks on monday... no way I'm hauling 40kg of aluminium over there for a jaunt.
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Old Jul 17, 2008, 12:34 PM
Needs brain lubrication
biber's Avatar
Aachen, very western Germany
Joined Dec 2004
1,391 Posts
Jonas, if you have the sparetime, I'd take a set of them, too.

Serious, cool stuff you're doing there.

Keep up the muffin... erm... good work!

biber
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