Hello guys. Today I've made my own Venturi too, based on the sketch from Zippi. Thanks Zippi.
The Venturi is made from 3 brass pieces and one plastic chamber.
The first brass piece (the rightmost one) is a quick-connect air hose coupling. I adjusted the thinner end to be exactly 6.05 mm in exterior diameter, to match my 6mm drill for the plastic chamber.
The nozzle is second brass part from right. I machined the body to fit the inner diameter of the hose coupling (about 4,5 mm). The cone on the end is very important; it has an agle of 16 deg (15 to 18 seems fairly good) that allows it to extend about 18,5 mm in the vacuum chamber, covering very well the suction hole on the bottom. (~5mm)
The third brass part (the suction coupling on the botton) is somewhat too complicated for its role. Anyway, I am planning to use the vacuum pump not for a vac table (as most of you seem to) but for bleeding the brakes on my BMW. Therefore, the suction coupling matches the various tubes and connectors used in the process.
The design is very simple and also very tolerant to errors. The three most important things are the inner nozzle diameter (1mm), the output inner diameter (2.5mm) and the suction part inner diameter (2mm). I found this values by making 4 testing vacuum chambers with different parameters until the I've got the best suction. The nozzle position in the vac chamber is somewhat important too. I tried different positions until i got it right (somewhat very very close to the output hole).
If you are interested in more details, I've made a couple of photos of the parts as well as sketch, to the best of my abilities. The sketch is also in CorelDraw 13 format (the zip file), scaled 1:1 so you can actually measure on the sketch any dimension you want. In fact, Corel has a very good measuring tool.
Well tha't it. A couple of words more, for the ending, a sort of FAQ:
Spelling. I am sorry for amy spelling mistakes I may have made, but English is not my native language.
Why I did this? Well, here in Romania, things are a little bit different form other places. Tool professionals didn't even heard of Venturi before, so imagine what happens when I want to buy a redy-made venturi pump. A ... what? they ask ...
So, i needed one. Starting from Zippi's idea, I made a few testing of my own, and, "voila!".
Sketck errors. If any, remember I am only a hobbist machinist, and the spare time is little.
Well, I guess that is all. I hope you guys find it useful the few pieces on info I have shared. If you have any questions or, more important, upgrading ideas, please fell free to tell me.
Oh, I almost forgot! How does it perform? In one word: WELL! I don't have any means to measure the vacuum, but if I try to extract the air from a plastic bottle, well, let's say it becomes **very** thin. I found out that the pump is most efficient at about 5-6 bar of comressed air. Anyway, it is way to powerfull for bleeding the brakes. I generaly use it with 0,5 - 1 bar of compressed air. |