homemade dredge nozzle

[cmatue1]

My $18 homemade nozzle 1.5" pressure into a 2" suction.... not sure if it will work, but what the heck....

 

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[Goodyguy]

Did you put a restrictor jet in the pressure supply tube?

Needs to be 1/4 the size of the 1.5 supply to create the proper pressure. So the jet opening should be 3/16"

 

[cmatue1]

Nope....... whoops. Can I put it where the hose connects to the tube? Or do I need to take it apart and put it at the junction?

 

[Goodyguy]

Nope....... whoops. Can I put it where the hose connects to the tube? Or do I need to take it apart and put it at the junction?

Has to be in the junction at the end of the supply. Cut and install a reducer or two. may work with 1/2" if the pump is strong enough.

 

[cmatue1]

Thank you...... this is why I joined this forum. There is actually some people who know what they're doing.... I don't.

 

[omnicron]

The problem with plastic is it'll break easy. Also you need a restrictor on the suction end to stop bigger rocks from getting sucked up, causing a plug up. Seriously cm, your going down the same road I traveled 2 years ago. I spend much money and time building a 2.5" dredge and only recovered a few hundred dollars in gold. The moral here is your spending money on things that might/wont work or will break when you could just spend a little more and get what will work. Look at it this way, you spend $20 building that, it doesn't work so you try to mod it to work...another $5....then scrap it or it breaks...then try something else...another $25 or more.... $50 spent and still don't have something that is working look it should. You bite the bullet and buy a nozzle for $100 so now your out 150....see my point.

 

[Hoser John]

Never use plastic as muffler shops have plenty of extra pieces in trash piles for next to nuttn. NEVER EVEN NO WAY restrict that nozzle intake except for a ring set off about a inch to allow for rock removal from nozzle that get stuck there. It allows water to come around and enable easier removal-John

 

[Jason in Enid]

That 90 degree turn is guaranteed to be a plug magnet.

 

[russau]

Not necesarly! hes useing a long sweep 90 that has less restriction than a regular ole 90, and if he learns which rocks to pitch and NOT get sucked up the hose, he should be fine for maybe 1 summer.and hes probly not going to be useing a mask, so feeling all thats under water will be real critical for him... after the first summer, he can go out and buy a new suction nozzel because used ones are impossible to find!

 

[Jason in Enid]

... after the first summer, he can go out and buy a new suction nozzel because used ones are impossible to find!

That's true, they are almost as rare as used jet log!

 

[cmatue1]

I plan on wrapping the nozzle with 1 inch chicken wire. And I'll have a mask and snorkel so I can attempt to see what I'm doing......

 

[cmatue1]

Made a new nozzle with a 3/8" inside diameter 4" long pressure jet installed inside the pipe at the junction

 

[russau]

that ought to get you started. go get some gold.

 

[Timberdoodle]

A few problems yet to work out. I recommend cutting back the restrictor to less than 1/2" long. The losses of psi incurred from friction losses through the 4"long restriction are going to result in poorer performance. If you factor a 1-1 motive fluid feed to suction and want to draw 80gpm through the nozzle then your going to need 80gpm through the jet.

80gpm through 4" of 3/8 diameter pipe calculated psi loss is 63psi
80gpm through 1/2" of 3/8 diameter pipe calculated psi loss is 7.8
80gpm through 1/4" of 3/8 diameter pipe calculated psi loss is 3.8

So the losses are significant as the length increases. I hate to bring it up (Sorry GG), but the ratio of 1/4 the diameter is to your 2" inlet so a 1/2" jet orifice is better suited than 3/8. If you are not running a high pressure pump than slightly larger is even better. To get 80gpm through a 1/2" jet orifice would require 50psi on a well designed orifice and even more on a homemade. I hope this helps, I have done the same as you in building my own jet's, just trying to help save some aggravation in the process. Most of the "tools" for calculating friction loss etc.. are available on-line.

You can cut the friction loss numbers above in half for a 1/2" restrictor pipe nozzle.

 

[Goodyguy]

Definitely just use a washer as your restrictor.

 

[Timberdoodle]

Yes as GG said a washer will work just fine and is better than welding up something. If you have the ability, then using a punch to modify the washer with a funnel shape will give you even better flow and focus of the jet stream. See the link Flow through an orifice for orifice types. The k=.97 is what I am referring to.

 

[cmatue1]

I tried using just a washer. It didn't give me a directional blast more like a fan spray. A directional blast will push the material better. Maybe I'll cut it down to an inch

 

[Timberdoodle]

I think you are still going to want to go to 1/2". This is a good time to experiment with the 3/8 by cutting some length off a bit at a time and test. Find the best operation then try it with 1/2"

If you can modify a fender washer as described in my last post, I think you will like the outcome over the fan spray. You really only need about 1/4" depth of focus area to get a good jet.

 

[cmatue1]

It already seems to suck pretty good with my backyard tests. But if I can get better suction I'm all for it. I'll try modifications tonight

 

[cmatue1]

I forgot I had a tube bender at work. So I whipped together a steel nozzle too. The jet is a 1/2" I. D. And 1/2" long. Pay no attention to my booger welds, my first time ever tig welding