Biopowered - vegetable oil and biodiesel forum
Biodiesel => Biodiesel equipment => Topic started by: greasemonkey on August 08, 2014, 09:03:07 PM
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On the Wiki page on Venturi, it states the angles as 10 degrees inclusive, and 60 degrees inclusive.
Would I be right in thinking, that if there was a line running horizontally, through the middle of the pipe, then the angle of the edge of the pipe would be 5 degrees one side, and 5 degrees the other?
To put it another way, if I was to turn down a wooden plug, for casting, I would find the axis of the wood, and turn down a taper, that would be slopping out 5 degrees from the axis?
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Correct.
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Try drawing one in Sketch-up!
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Drawing things in sketchup is the new printing stuff with 3d printer!
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Magic, thank you.
I think this one will be a fag packet design, or at least a piece of printing paper.
Another question for the more experienced metal casters. When it comes to the suction hole, what would it be like to make a sacrificial plug, out of clay or something, the exact right size, and pour with that, rather than trying to drill the hole afterwards. Or is that not practical.
I haven't calculated he size of the hole yet mind. If it happened to be exactly 6mm, than there would be no question but to drill it.
Ahh, no, that's not going to work.......
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Right, first things first.
What pump will you be using with the venturi as that will determine the throat diameter.
Throat diameter will govern the vacuum diameter, I use 3 x 6mm diam holes on an 8mm throat.
We need more info.
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IIRC, my pump is rated at 70LPM, but I will have to check that.
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IIRC, my pump is rated at 70LPM, but I will have to check that.
You'll need an 8.7mm diam throat but you could get away with 9mm, it might slightly reduce the vacuum but it's a nice round figure to work to.
With a 9mm throat you can use a 9mm vacuum hole, IF you can drill it accurately.
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Cheers, that was my next question, how much difference would the extra 0.3 mm make.
I can probably get it in the lathe to drill it, somehow.
Cheers, I update when I get on with it. Hopefully soon.
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Cheers, that was my next question, how much difference would the extra 0.3 mm make.
I can probably get it in the lathe to drill it, somehow.
Cheers, I update when I get on with it. Hopefully soon.
I was referring to the accurate vacuum hole drilling as the throat will be formed during the casting.
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If you are going to drill the throat in a lathe, be careful you don't get a jet effect from it.
There's a bit on the wiki about it here ... http://www.biopowered.co.uk/wiki/Venturi#Installing_a_venturi
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I can see what you mean about the jet effect. I presume that is caused by the parallel walls of the throat. once it's been drilled.
I was going to cast that bit anyway, and drill the vacuum hole. I was thinking I'd clamp the piece, and spin the drill.
I will have to do a bit more pondering, and work out what way is best, given what tools I have access to.
I'm also considering spinning it.
Been watching a few Utube vids, and it looks like it might spin not to bad, but I'd have to make a few tools for the lathe, and possibly spin it in two parts, and join them.
Something to mull over.
Thanks for your help Gents.
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I've made a couple of spun venturis. I only have a little ML7 lathe and it puts way too much stress on the components.
I had some photos I posted on the VOD a while back, but I can't find them now. They showed damage to the tool post (very heavily burred edges) just from the pressure of leavering the tool.
It was a really interesting exercise, and produced good venturis, but didn't do the lathe any favours at all.
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Did you anneal the copper?
The lathe here is a horse of a thing. It took two of us to lift the bed, without the feet and motor. It's only 4 ft long.
Bit of a bargain father had off an old boy who was clearing out.
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Yes, annealed the copper several times, but it soon work hardened.
I was using 22mm copper pipe which I shrunk to a turned mandrill. It may not have been the best type of copper to use, but it was readily available.
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The quickest way to feck a lathe is to use it for spinning, there are some serious loads applied to shift the metal about.
Don't do it.
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Ah, right, scratch that then. I've got plenty of time to think about it now, while i weld the van up for MOT.........
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When I was in the trade we referred to normal lathe work as turning. I never heared of spinning until I came on this site. What do you mean by the term. Is it it as I understand turning to use a tool mounted into the tool post to cut material off of the spinning material which is held in the chuck, or something totally different ?
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Its an art lots on youtube.
http://www.youtube.com/watch?v=43N44ICyuEU
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Wow, thanks. That explains how lots of things are made that I always thought were pressed.
Can see how it's brutal to tool posts tho.
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Wow, thanks. That explains how lots of things are made that I always thought were pressed.
Can see how it's brutal to tool posts tho.
I've just watched the tank dome end being made, a bit farty, the last one I watched being spun up was 40ft diam and 6" thick.
A proper dome end.
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I've just watched the tank dome end being made, a bit farty, the last one I watched being spun up was 40ft diam and 6" thick.
A proper dome end.
Course Jim would know, that was the time they made his trumpet!
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While on the subject of shaping metal things, if spinning isn't well known, has anyone come across hydroforming?
https://www.youtube.com/watch?v=I_Z3AIFSd60 (https://www.youtube.com/watch?v=I_Z3AIFSd60)
https://www.youtube.com/watch?v=ppXRMTeR2NQ (https://www.youtube.com/watch?v=ppXRMTeR2NQ)
https://www.youtube.com/watch?v=y0aphiMT4VE (https://www.youtube.com/watch?v=y0aphiMT4VE)
https://www.youtube.com/watch?v=RQE9cJApSgQ (https://www.youtube.com/watch?v=RQE9cJApSgQ)
And the engineering world's biggest nutter ...
https://www.youtube.com/watch?v=llhcATrmsBg (https://www.youtube.com/watch?v=llhcATrmsBg)
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I hate to say it but yes, I've known about it for donkeys years.
A method use in the manufacture of brass instruments since just after the invention of hydraulics.
How about explosive forming?
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I know you'd know!
Explosive forming ... yes.
If we're building a hot tub it would be a perfect tank. A little bit of oxygen and acetylene with womble in control, no problem!
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Does the Womble survive though.
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Does the Womble survive though.
The idea is that he doesn't.
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Jim doesn't hydroform, he just blows into the welded parts and up they pop.
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Jim doesn't hydroform, he just blows into the welded parts and up they pop.
Years of practise.
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That's what you mean when you say he blows his own trumpet. Here's me getting it wrong again. :)
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Seeing as hydroforming was mentioned.
http://hackaday.com/2014/08/13/hydroforming-in-the-garage-with-a-pressure-washer/ (http://hackaday.com/2014/08/13/hydroforming-in-the-garage-with-a-pressure-washer/)
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Excellent vid James,, thanks for sharing, I also just watched his 70mph mobility scooter build, and bookmarked his channel for future viewing.