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 Post subject: Canopy repair
PostPosted: 10 May 2007 10:14 pm 
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Joined: 26 Feb 2004 07:54 pm
Posts: 1660
Location: Tai Po, HK
What can be done when a canopy is broken due to old age ? AA glue seems not working well with that material :(
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 Post subject:
PostPosted: 11 May 2007 12:12 am 
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Joined: 26 Feb 2004 06:07 pm
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Location: Hong Kong
無得救 :!: 一喺用balsa做個mould,然後玩吸塑,或者買過個 :shock:


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 Post subject:
PostPosted: 11 May 2007 09:59 am 
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Joined: 26 Feb 2004 05:08 pm
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Location: Hong Kong
Hi Ah Mak,

Is it the Robbe ASH26 canopy? I have one and can make a mould for you.

Anyone know where can provide small volume vacuum forming service?


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 Post subject:
PostPosted: 11 May 2007 11:11 am 

Joined: 02 Aug 2004 10:14 am
Posts: 621
Hi Mak and CM,
Would you please measure the dimension of the canopy. I have to see if my forming platform and oven are large enough.

Mak, there is a special glue for "canopy" or try contact cement (clear type). At least you can put the pieces together and then make a plug.
CA glue is brittle when cure. Canopy glue is flexible and is available at Waigo (hopefully).


CM, it is easier if your canopy is uncut.
For moulding the plug, please consider using yellow plaster.

Yeung


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 Post subject:
PostPosted: 11 May 2007 03:09 pm 
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Joined: 26 Feb 2004 07:54 pm
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Location: Tai Po, HK
CM Cheng wrote:
Hi Ah Mak,

Is it the Robbe ASH26 canopy? I have one and can make a mould for you.

Anyone know where can provide small volume vacuum forming service?


CM,
Yes, it's the Robbe ASH26 canopy.

How are you going to make the mould?
There are 2 methods in my mind. each have its disadvantage.

1. pour plaster in to the canopy.
Plaster is heavy which might break the original.

2. spray self expending foam in to the canopy.
This foam is light, hence may not fill up all spaces to form a good mould.


Yeung,
I didn't measure the size, but it should be around 1.5' x 9"


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 Post subject:
PostPosted: 11 May 2007 03:30 pm 
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Joined: 26 Feb 2004 07:54 pm
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Location: Tai Po, HK
I have an idea which might work without danger of breaking the original canopy due to weight.

We can put the canopy on water, and allow the canopy to sink into water, as we pour plaster into it.
We must keep the edge of the canopy above water surface. so that water outside the canopy will balance out the pressure inside the canopy.

There is another problem !
With that much plaster, the whole thing might get very hot and deform the canopy!
Yeung, does yellow plaster generate much heat ?


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 Post subject:
PostPosted: 11 May 2007 03:56 pm 

Joined: 02 Aug 2004 10:14 am
Posts: 621
Mak,
You really do not fully fill the canopy with plaster, you can insert some foam in the center. (Less weigh and less cost). The plaster is thick enough that the foam will not float up.
Yellow plaster will not melt down you canopy. White plaster or fiberglassing with thick layer of epoxy will generate too much heat.

Your concern about overloading the canopy is correct. Big volume and mass of the plaster will push the canopy out and distort the shape. So it is necessary to support it outside before pouring in plaster. You can frame it with cardboard, white foam or some wood strip.

Putting the original canopy in water will make life harder. If the canopy is not rigid enough or supported, the heavy and dense plaster will still pushing out.

Neither the expanding foam method sounds good. The hot plastic sheet will be placed and pressed down to this plu and I don't think the foam one can hold it.

Yeung


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 Post subject:
PostPosted: 11 May 2007 04:14 pm 

Joined: 02 Aug 2004 10:14 am
Posts: 621
Mak,
It is necessay to know the height of the canopy so as to estimate the size of the plastic sheet. It is not just the size of the base but also the material of the lateral surface.

It seems that my equipment cannot handle your project.
A large heater and a large forming platform are needed. For the platform, you can consider a drawer of a cabin or cupboard. But a large oven which can accomodate a big turkey is necessay. Mine is just a small one.

Is it possible to make it two portions?

Yeung


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 Post subject:
PostPosted: 11 May 2007 07:09 pm 
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Joined: 26 Feb 2004 07:54 pm
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Location: Tai Po, HK
Yeung wrote:
Mak,

It seems that my equipment cannot handle your project.
A large heater and a large forming platform are needed. For the platform, you can consider a drawer of a cabin or cupboard. But a large oven which can accomodate a big turkey is necessay. Mine is just a small one.

Is it possible to make it two portions?

Yeung


Hi Yeung,
I just measured the size.
It's 21" x 8" x 5"

Is it possible to hold a 2000W heater or a hair dryer above the setup to heat things up, while pulling vacuum with a vacuum pump ?


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 Post subject:
PostPosted: 11 May 2007 10:44 pm 

Joined: 09 Sep 2004 04:57 pm
Posts: 688
Don,t forget .I have a factory in china,we can do any type of canopy .any colour ,any thickness !!!!!!!!!!sent me your mold master !!!!


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 Post subject:
PostPosted: 17 Jun 2007 07:16 pm 
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Joined: 26 Feb 2004 05:08 pm
Posts: 2941
Location: Hong Kong
原本用呢個方法減少石膏用量,但太杰失敗左,最後一層層塗上去。
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阿麥,你桶石膏用晒嘞。 :)
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 Post subject:
PostPosted: 17 Jun 2007 09:05 pm 
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Joined: 26 Feb 2004 07:54 pm
Posts: 1660
Location: Tai Po, HK
CM,

Is that a solid plaster mould ? It looks real smooth :D
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 Post subject:
PostPosted: 17 Jun 2007 10:55 pm 

Joined: 09 Sep 2004 04:57 pm
Posts: 688
Sent me as soon as possible !


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 Post subject:
PostPosted: 18 Jun 2007 07:44 pm 
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Joined: 26 Feb 2004 07:54 pm
Posts: 1660
Location: Tai Po, HK
CM,

Did you sent the canopy to Ah Kin yet ?
If not, better take it with you to MOS.

I'm looking forward to fly the ASH26 together with yours. :D

BTW, start your ASH26 project early, and post the installation photos.
I need reference for my first scale glider project :o


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 Post subject:
PostPosted: 18 Jun 2007 10:13 pm 
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Joined: 26 Feb 2004 05:08 pm
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Location: Hong Kong
Hi Mak,

The mould is not solid. Your plaster is not enough to fill it up :x

I will bring the mould to MOS tomorrow. It is very heavy, I think it is over 8Kg.


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 Post subject:
PostPosted: 19 Jun 2007 01:45 am 
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Joined: 26 Feb 2004 07:54 pm
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Location: Tai Po, HK
CM Cheng wrote:
Hi Mak,

The mould is not solid. Your plaster is not enough to fill it up :x

I will bring the mould to MOS tomorrow. It is very heavy, I think it is over 8Kg.


What! It's not finished ?
Well, I have more plaster.
How much plaster should I bring ?


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 Post subject:
PostPosted: 20 Jun 2007 12:36 am 

Joined: 09 Sep 2004 04:57 pm
Posts: 688
埃!!!!!!!!!!!!!有D後侮,咁重...唔係..應該係咁XYZ###重,點囉反大陸,真大濟!!!!!!要用老土手拉車....(門+小)!!!!!!!!


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