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australian electronic gold prospecting forum.com  |  Recent Posts
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 91 
 on: Friday March 23 2018 14:17:16 AEDT PM 
Started by IBGold - Last post by Muntari
Hi All,

More photos of Vacuum testing on platen.

Simple test to see how long the vacuum would hold in general.

The initial draw was more than enough and it held steady, so platen is fine.

I lifted some duct tape in one corner (last photo) and the vacuum dropped quickly as expected.
Put tape back on and it held steady, so all good I think.

On another front, I tested 4 x 500w halogen flood lights set up as a heater and it worked. Temperature at a distance of 200 mm rose to 290 deg C.
The problem is, I think it will require 6 units for even heat on the 750 x 750 mm size bed. so that idea is out the window or at least a re-think is in order.
There is another halogen heat source I spotted at Bunning's hardware which might just do the trick, more on that later.

Cheers

Muntari


 

 92 
 on: Friday March 23 2018 13:47:13 AEDT PM 
Started by Aziz - Last post by Muntari
Hi gef2,

The coil Q and inductance will  decrease depending on conductivity of shield, aluminum, copper, zinc, steel etc.
But adding extra cable length can increase inductance, it would have to be a fair bit of cable to get that 20-40% increase though.

I have found that the decrease in Q of the inductor will be affected with some materials worse than others, still the same net effect though.

I use Nickel shielding mostly and always with a gap in the shield (no shorted turn) but I don't see a drastic reduction in Q or inductance, certainly not 20-40% the distance between shield and spacer will of course play a part.




Cheers

Muntari



 93 
 on: Friday March 23 2018 13:04:51 AEDT PM 
Started by Aziz - Last post by gef12
Query regarding inductance ...
After coil is wound and inductance is example 500uH ..
will the inductance increase with sheilding and cable or decrease ..
I read somewhere that it will decrease by about 20 or 40 percent ..
yet seeing elsewhere that it will increase from the original wind of coil ..
thoughts .
I have a current coil (plain - without shield or cable etc ) at 1000uH using Litz on
HDP spider flat wound.

 94 
 on: Friday March 23 2018 00:16:36 AEDT AM 
Started by Muntari - Last post by Muntari
Hi All,

So after receiving some good information,

I can say with a very high degree of confidence, White's and Carl did not copy any of my ideas of using accelerometers in PI coils.

I didn't really think they had to be honest  and like I said at the top of the post, I did find it (the patent) interesting as it took me by surprise to actually see a patent on it.

I can see, looking back at my posts where it is possible to draw the wrong conclusion.

My opinion of not sharing anything on forums that you might want to use commercially or even patent has still not changed however  happy face

Thought I should set the record straight.

Cheers

Muntari


 95 
 on: Thursday March 22 2018 17:01:36 AEDT PM 
Started by IBGold - Last post by Muntari
Hi all,

Here are some progress photos of the modified vacuum former platen.
I have inserted some nylon spacers into the 6 mm holes and made the grooves 1.5mm deep after some advice from Ian.
Only had 1,000 to press in, still quicker than re-machining the top again.
Added some 40 mm aluminium spacers to bottom side (the Lexan tank is 40 mm high and 10 mm thick) to prevent collapse when vacuum is applied.
There will be a fine stainless steel mesh placed between mold and platen to further help even out vacuum flow.
Areas that are not covered by the mold during forming, will be sealed with the blue plastic wrap you see on the cnc table. It comes on a 300 mm wide roll and I generally use it to protect parts once machined but is perfect for the job.
I have used what materials I had laying around the workshop and modified to suit....

Did some testing on vacuum last night and it works just fine.
Tonight, I'll assemble everything, then its just the heating section to do.

Btw, those with a keen eye may have noticed the grooves are offset to the holes, they should have been centered on the holes but when I zeroed the CNC, I didn't notice the offset until it was on the second set of angle cuts and by that time, I thought, don't bother, its not going to stop it working.

More later

Cheers

Muntari



 96 
 on: Thursday March 22 2018 16:08:32 AEDT PM 
Started by Doug - Last post by Doug
ExxonMobil Talks a Good Game, but It's Still Funding Climate Science Deniers
  
link-http://www.truth-out.org/news/item/41172-exxonmobil-talks-a-good-game-but-it-s-still-funding-climate-science-deniers


Climate Deniers Exposed: Top Scientist Got Funding from ExxonMobil, Koch Brothers, Big Coal
  
link-https://www.youtube.com/watch?v=8E11v7DY4UM

  
link-https://www.youtube.com/watch?v=wnv0DJJPopQ
Global Warming Confirmed By Koch Funded Researchers!!!!
  
link-https://www.youtube.com/watch?v=a6FbISa3nFQ
doug smile

 97 
 on: Thursday March 22 2018 11:18:24 AEDT AM 
Started by Alex - Last post by WM6
  

Here are some progress photos of the modified vacuum former platen.



Great work, Muntari.

Wish to see some video, how it works, if possible.

 98 
 on: Thursday March 22 2018 09:47:16 AEDT AM 
Started by Alex - Last post by Muntari
Hi all,

Here are some progress photos of the modified vacuum former platen.
I have inserted some nylon spacers into the 6 mm holes and made the grooves 1.5mm deep after some advice from Ian.
Only had 1,000 to press in, still quicker than re-machining the top again.
Added some 40 mm aluminium spacers to bottom side (the Lexan tank is 40 mm high and 10 mm thick) to prevent collapse when vacuum is applied.
There will be a fine stainless steel mesh placed between mold and platen to further help even out vacuum flow.
Areas that are not covered by the mold during forming, will be sealed with the blue plastic wrap you see on the cnc table. It comes on a 300 mm wide roll and I generally use it to protect parts once machined but is perfect for the job.
I have used what materials I had laying around the workshop and modified to suit....

Did some testing on vacuum last night and it works just fine.
Tonight, I'll assemble everything, then its just the heating section to do.

Btw, those with a keen eye may have noticed the grooves are offset to the holes, they should have been centered on the holes but when I zeroed the CNC, I didn't notice the offset until it was on the second set of angle cuts and by that time, I thought, don't bother, its not going to stop it working.

More later

Cheers

Muntari

 99 
 on: Wednesday March 21 2018 23:49:07 AEDT PM 
Started by Aziz - Last post by Muntari
Hi Aziz,

That's good news will be good to get some testing on coils soon.
Won't be long now I think. good luck
I tested the platen on vacuum former tonight and it's working very well, so I can get back on to test coils again in a day or so.

Cheers

Muntari

 100 
 on: Wednesday March 21 2018 23:41:12 AEDT PM 
Started by Aziz - Last post by Muntari
  
Hi All,

The Litz spider RX coil is wound the specifications are 429 uh resistance 4.4 ohms and S.R.F coil on former 620 KHz.

Regards, Ian. happy face

Hi Ian,

That's great news, much better, well done.

Cheers

Muntari

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