Search found 13 matches

by stup86
Wed Jun 19, 2019 4:11 pm
Forum: Hybrid Cannons
Topic: Thoughts on my piston valve design
Replies: 29
Views: 4019

Re: Thoughts on my piston valve design

Thanks Moonbogg. Updates to the following: - Bumper OD reduced. There is now radial clearance of 1.5mm (Annoyingly, I didn't mean to completely fill the gap!) - Thickness of front seal increased form 8mm to 15mm (I'll need to find something suitable to make this from) - Screw securing front seal has...
by stup86
Wed Jun 19, 2019 7:55 am
Forum: Hybrid Cannons
Topic: Thoughts on my piston valve design
Replies: 29
Views: 4019

Re: Thoughts on my piston valve design

Thanks for your answer’s guys. Some people don't mind working on the edge of the material specifications and operate on the assumption that something will probably give, while others won't touch anything without a 3 or 4 times safety margin. I can see the appeal, from a weight perspective, in gettin...
by stup86
Tue Jun 18, 2019 3:17 pm
Forum: Hybrid Cannons
Topic: Thoughts on my piston valve design
Replies: 29
Views: 4019

Re: Thoughts on my piston valve design

So, as I'm trying to get the piston assembly weight down to as little as possible, I've started to (try to) analyse the part in SolidWorks. My company used to use SolidWorks before moving to Catia, so I only have access to a basic version - meaning SimulationXpress is all I can run. I HAVE NEVER PER...
by stup86
Sun Jun 16, 2019 3:57 pm
Forum: Hybrid Cannons
Topic: Thoughts on my piston valve design
Replies: 29
Views: 4019

Re: Thoughts on my piston valve design

There's something about the orientation of the piston that isn't sitting right with me. I feel that having a design where the piston moves vertically, essentially sealing the chamber rather than the barrel would be better. As a picture is worth a 1000 words, here we go: Cannon_alternative.jpg What'...
by stup86
Sun Jun 16, 2019 6:02 am
Forum: Hybrid Cannons
Topic: Thoughts on my piston valve design
Replies: 29
Views: 4019

Re: Thoughts on my piston valve design

Also, I think I'm going to change the tee used in my design to swept tee as shown below:
Swept tee
Swept tee
black-malleable-pitcher-swept-tee.jpg (19.58 KiB) Viewed 2142 times
Thoughts?
by stup86
Sun Jun 16, 2019 5:31 am
Forum: Hybrid Cannons
Topic: Thoughts on my piston valve design
Replies: 29
Views: 4019

Re: Thoughts on my piston valve design

There's something about the orientation of the piston that isn't sitting right with me. I feel that having a design where the piston moves vertically, essentially sealing the chamber rather than the barrel would be better. As a picture is worth a 1000 words, here we go: Cannon_alternative.jpg What's...
by stup86
Sun Jun 16, 2019 5:15 am
Forum: Hybrid Cannons
Topic: Thoughts on my piston valve design
Replies: 29
Views: 4019

Re: Thoughts on my piston valve design

mrfoo wrote:Depending on dimensions, I might be able to sort you a block of teflon or two, for the cost of postage from cheese-eating surrender-monkey land. Drop me a PM if you're interested.
Thank you. Once I've finalised the piston design, I'll send you some dimensions and we'll sort something out. :D
by stup86
Sat Jun 15, 2019 5:54 pm
Forum: Hybrid Cannons
Topic: Thoughts on my piston valve design
Replies: 29
Views: 4019

Re: Thoughts on my piston valve design

The next issue I see is the bumper. I assume that little rubber washer in the back of the pilot is a bumper? Or is that used as a guide for the rod? It looks like a bumper. Correct, it is a bumper. I'm not exactly sure of the hardness but you're right, it does look woefully inadequate when consider...
by stup86
Sat Jun 15, 2019 12:28 pm
Forum: Hybrid Cannons
Topic: Thoughts on my piston valve design
Replies: 29
Views: 4019

Re: Thoughts on my piston valve design

HGDT is a great program to determine this, as it is no longer available online I have attached a zip file. Thank you! Nice solidworks drawings by the way, I assume you have access to machining facilities if you intend to build this? Never really got in to Solidworks, this was modelled using CATIA. ...
by stup86
Fri Jun 14, 2019 4:28 pm
Forum: Hybrid Cannons
Topic: Thoughts on my piston valve design
Replies: 29
Views: 4019

Re: Thoughts on my piston valve design

I like the design. Thank you I'd like to see the barrel side diameter be closer to the pilot side diameter, similar to how you had it in your first drawing, but not quite that close. I see a small edge of engagement where the piston seats against the T-housing. I'd like to see a larger step there. ...
by stup86
Fri Jun 14, 2019 10:39 am
Forum: Hybrid Cannons
Topic: Thoughts on my piston valve design
Replies: 29
Views: 4019

Re: Thoughts on my piston valve design

The piston won't open. The area of the barrel side need to be smaller than the area of the pilot side. Thank you for replying. It was obvious really! I'm made some changes to the design, incorporating a weld-in bush to reduce the diameter of the piston at the barrel side. Again, any thoughts and co...
by stup86
Thu Jun 13, 2019 5:02 pm
Forum: Hybrid Cannons
Topic: Thoughts on my piston valve design
Replies: 29
Views: 4019

Thoughts on my piston valve design

Hi all, Attached are some images of the designs of my first hybrid cannon. I've been working on piston valve and wanted people thoughts on the design that I'm at currently. I plan to use o-rings to seal the chamber from the barrel - anyone had any luck with a design like this? All comments welcome N...
by stup86
Mon Jun 10, 2019 7:53 am
Forum: Hybrid Cannons
Topic: HYBRID FUELING 101
Replies: 105
Views: 28268

Re: HYBRID FUELING 101

Hello all, 1st post here. I've been telling myself I would build a hybrid cannon since I first built a spudgun over 10 years ago. I've started working on the design on CAD and should have something to work with in the next few weeks (when time allows) There seems to be quite a lot of contradicting i...