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Author Topic: Welman build  (Read 17987 times)

bbdave

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Re: Welman build
« Reply #100 on: September 21, 2013, 02:46:22 pm »

I will get some discs cut these ones are 77.7mm i think I'll round up to 78mm and dress them down if needed the reason for using acrylic is it's  free and i can get it cut free plus it does the job :-))


Dave
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Circlip

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Re: Welman build
« Reply #101 on: September 21, 2013, 02:49:18 pm »

Only mentioned it for the end caps, not the main body. Laser cutting? haven't seen an o-ring groove cut using that. Given that many need to be told what length their "Scale" model is, percentage compression is a whole new ball game.  {-)   and percentage of what dimension?At least manufacturers figures give a starting point and don't forget, in this application, if the fit is too tight, you can machine the groove a bit deeper to give a slacker seal, hard to put it back on if too slack.
 
  In the case of Axial seal, as Subdriver has stated, limiting factor is how much you swing on the spanner.
 
  Regards   Ian
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bbdave

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Re: Welman build
« Reply #102 on: September 21, 2013, 04:53:34 pm »

Ok the % is the C.S. of the o ring which in my case is 3.53mm so %20=.706mm the I.D. of the tube is 84mm minus 2x3.53 plus 2x.706mm which= 78.352 for the middle disc i think {:-{


Dave
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Subculture

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Re: Welman build
« Reply #103 on: September 21, 2013, 07:21:40 pm »

You got it, Dave. 78.4mm will be sufficient. Bear in mind that tubing varies in diameter even along the length.

bbdave

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Re: Welman build
« Reply #104 on: October 03, 2013, 04:39:09 pm »

Bingo looks like a spot on fit this time will the friction be enough to hold them in or is it best to hold them in mechanicaly?



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Subculture

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Re: Welman build
« Reply #105 on: October 03, 2013, 04:58:51 pm »

As you are pressurizing the internal cylinder you will need some means of retain the caps to prevent them popping off.

Various ways of doing that, a good way is to take a leaf out of Robbe's book and use the tech rack to keep things buttoned up.

Davy1

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Re: Welman build
« Reply #106 on: October 03, 2013, 06:36:16 pm »

I take it you can remove/replace the cap easily? With firm hand pressure.
(The photo makes it look a little tight - thats all.)

What ballast system are you planning to use? (To help assess any overpressure)

David
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bbdave

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Re: Welman build
« Reply #107 on: October 03, 2013, 07:38:08 pm »

I may wet and dry them a little but i'd rather a good seal but any reduction will be tiny but I'll make sure they are easy enough to remove specialy the battery end.

Dave
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Re: Welman build
« Reply #108 on: October 03, 2013, 08:27:00 pm »

If you think the seal is a little tight, you can file gently around the circumference of the inner disc with a small square file.

You do have quite a bit of tolerance with these seals, especially as you're using a seal on the fatter side.
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