Joined: 18 Jun 2004
Posts: 3842
Location: Queensland near Brisbane
Beautiful.
Why did you choose a straight spring rather than a conical one? Have you determined your valve's Cv? What is the thickness of your piston? _________________ So even the rain that falls isn't actually going to fill our dams and our river systems
Sun May 10, 2009 12:08 pm
assassin
Joined: 27 Jun 2004
Posts: 1105
Location: SunshineCoast
Its a XU1 spring. No less than 10 CV. Which part of the piston?
I quickly designed a valve that would suit your ram today. But would your ram handle it and could you make your bot handle it? _________________ Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
Albert Einstein.
Sun May 10, 2009 12:31 pm
Philip Experienced Roboteer
Joined: 18 Jun 2004
Posts: 3842
Location: Queensland near Brisbane
I was wondering how thick the UHMW (?) is. Actually, I would be interested to see the dimensions of all of the parts of the piston valve and four bar mechanism.
I would like to put an enormous Trent valve in Marauder and if it dies, it dies. Woody's Flipper Calc for Flow and Throw says a CV of up to 18.65 would suit the ram. http://www.teamonslaught.fsnet.co.uk/pneumatics.htm
I would like to build me an entire Trent valve and ram combination at 60 * 60 mm. This would be the basis of a complete new bot. I will need to be more financial before I do anything new. _________________ So even the rain that falls isn't actually going to fill our dams and our river systems
Sun May 10, 2009 1:58 pm
assassin
Joined: 27 Jun 2004
Posts: 1105
Location: SunshineCoast
15mm
A new valve could be done cheaply. Your piping is 1/2 inch? That's like 12 CV, so a valve designed around 1/2 inch piping would be the go. Which is the same as the ram on these pages. _________________ Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
Albert Einstein.
Sun May 10, 2009 2:11 pm
Philip Experienced Roboteer
Joined: 18 Jun 2004
Posts: 3842
Location: Queensland near Brisbane
Yes I have 1/2" BSP piping. My current CV is only 2.2, IIRC. 12 would be a huge improvement. _________________ So even the rain that falls isn't actually going to fill our dams and our river systems
Sun May 10, 2009 3:37 pm
Philip Experienced Roboteer
Joined: 18 Jun 2004
Posts: 3842
Location: Queensland near Brisbane
This is the sort of thing I had in mind. Not to scale. http://robowars.org/forum/album_pic.php?pic_id=1504 _________________ So even the rain that falls isn't actually going to fill our dams and our river systems
Sun May 10, 2009 4:14 pm
assassin
Joined: 27 Jun 2004
Posts: 1105
Location: SunshineCoast
I could do this with my lathe and drill press. _________________ Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
Albert Einstein.
Sun May 10, 2009 5:24 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
Any reason for choosing UMHW for he piston over stronger plastics like Nylon or Delrin? After having machined all three, I am not nearly as impressed with UMHW as I used to be.
Sun May 10, 2009 7:01 pm
maddox
Joined: 21 Dec 2006
Posts: 786
Location: Belgium
The softness of UMHW is a good way to assure a seal.
Also, I tried nylon for the piston itself in a few rams, and it did break,I replaced those with UMHW pistons, No more problems.
Sun May 10, 2009 7:11 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
Fair enough. I thought the O ring did all the sealing?
Sun May 10, 2009 7:15 pm
assassin
Joined: 27 Jun 2004
Posts: 1105
Location: SunshineCoast
The shuttle seals with aluminum to UHWM-PE. Nylon is too brittle Nick, as Mario stated and has tested.
Nylon is a lot better to machine and has it place, but not here.
thanks for the interest Nick and G'day Mario I've been away for a while, thanks for your help I'll be testing @ FP soon. _________________ Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
Albert Einstein.
Sun May 10, 2009 8:48 pm
maddox
Joined: 21 Dec 2006
Posts: 786
Location: Belgium
I mean for the shuttle. On a HDPE piston I use nothing or Viton Orings.
The shuttle in my version of the QEV ram seals directly on the ali body. And with harder plastics the seal is difficult to achive.
In the Burkert it's solved with a PTFE ring in the bronze shuttle. Just to give another example.
Mon May 11, 2009 9:57 am
Woody
Joined: 07 Oct 2004
Posts: 202
Location: UK
quote:
Fair enough. I thought the O ring did all the sealing?
I think you'll find that Trent's design is a face seal....could be wrong.
There will be however an O ring in the shuttle body.
So..... inlet port in the side ...outlet port at the top and bolted to the ram base via the staggered bolt hole pattern.
UHWM-PE shuttle ... probably stepped to give an annulus at the inlet port...with small bleed hole drilled thru it ...is pressed against the outlet by pressure of gas that bleeds thru the small hole...a NOS valve or similar actuates the valve by dropping the pressure below the shuttle.
This would be at the small end ( bottom ) of the pic.
Mon May 11, 2009 7:26 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
Thanks Woody. I was just looking at the ram seal. The shuttle valve still mystifies me, even though I have read several explanations; guess I'm a noob with gas weapons .
Mon May 11, 2009 8:12 pm
Glen Experienced Roboteer
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
its exactly the same as the plan c ram, except the shuttle valves are smaller in these designs same concepts anyway.
fantastic work Trent. nothing short of perfect
i think with the design the pressure holds the shuttle valve up against the bottom of the ram sealing it off. then the pressure under it is vented allowing it to drop down and the gas to flow around it into the ram.
all of these super flow valves are spin offs from spud guns. theres tons of websites on the majority of the designs AFAIK anyway _________________ www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz
Last edited by Glen on Mon May 11, 2009 8:20 pm; edited 2 times in total
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum