Trommel Build..question for the sparkys

[y4k]

As warrior said, if the rocks come out clean then your doing something right, speed will depend on soil/gravel type. Eg more clay, slower speed to clean the clay off. Depends on the length of your barrel (the longer the barrel the more cleaning area and time spent in the spray area), and the angle the barrel is set at (steeper the angle the faster the rocks go through. All makes sense doesn't it?

Cracka.

The barrel i got is 14' and 1m long so should keep the material in long enough to wash it off and break it down if needed and have plenty of cogs around to gear it to the speed im comfortable that its actually doing just that but am unsure as to how i can get the wiper motor to spin in a continual direction as opposed to the back and forth of the wipers.

 

[y4k]

The wiper motor goes in one direction, they use a cam system to make the blades go back and forth. All you will need is the wiper motor and maybe a dc speed controller to adjust the speed. Or try different cogs for the speed.

Cracka.

Haha ok u were too quick for me, posted as i was typing...ill get it all hooked up and see how it turns out, Cheers

 

[y4k]

Makes sense them working on a cam and not continually changing back and forth now u mention it, would put alot of uneccesary strain on the motor, never pulled one apart so was a fair bit of guesswork on my part lol.
Tks for the help

 

[cracka]

Just be careful of those cogs and chains running, especially with kids around, those round spinny things tend to attract small fingers. A safety cage even of light chicken wire would probably work well. If you get your finger caught between the chain and the cogs it will take your finger off (not joking either). You won't believe the torque in those motors. I will try to find some pics of the spit we made out of wiper motor, speed controller and racing bike cogs and chain.

Cracka.

 

[kawman]

found this..it may or may not be of use.. https://www.youtube.com/watch?v=xaIdL0N4qk4

 

[Nightjar]

Little difficult to see in this photo however the drive for this gold wheel is a wiper motor with a rubber disc drive cut from a piece of conveyor belt.
The motor is adjustable to keep pressure on the drive to prevent it slipping.
Feel sure you could drive your trommel using the same method rather than fiddling about with a chain drive?

 

[y4k]

Little difficult to see in this photo however the drive for this gold wheel is a wiper motor with a rubber disc drive cut from a piece of conveyor belt.
The motor is adjustable to keep pressure on the drive to prevent it slipping.
Feel sure you could drive your trommel using the same method rather than fiddling about with a chain drive?

http://i151.photobucket.com/albums/s122/nightjar3/Goldwheel1.jpg

The barrel i ended up getting is 14' and 1m long so i imagine i will be able to load it with a fair bit of material (provided im fit enough to do so) the weight in a spiral wheel would be reasonably easy to keep turning i imagine but with the weight of the barrel loaded and with water flying around its possible a friction drive wouldnt get the required purchase and would just slip?

 

[warrior707]

Most wiper motors have a high and a low speed the motor I use can go clockwise or anti clockwise depending on how you wire it up trial and error to work it out

 

[slowflow]

DC motors can be designed to run in one direction better, so check what you have. Running 'backwards' appears the same but results in lower torque an can change brush wear.

 

[Tathradj]

With a two speed motor you have 3 brush's.
Two are placed directly opposite each other and that is your high speed.
For low speed, The third brush which is off set comes into play.
With the later model design, A pulse width modulator is used.
Much cheaper and easier to produce and more expensive to buy.
The latter is the most efficient and effective way of speed controlling a DC motor.
Making sure you use heavy transistors with a good heat sink.
.
Direct drive wiper motors are a good choice providing that they do not have much weight on them
and to do that you use gearing and don't stall them.
With a one to two gear you half your speed and almost double your torque.

 

[Tathradj]

To work out your ratio's,
Divide the highest number by the lowest number.
36 teeth Large
12 small
36 divided by 12 = 3
every 3 revolutions by the small gear or cog will equal 1 turn by the large.
you have also nearly multiplied your torque by a factor of 3.
There is some loss with friction etc.
This is a bit rough but will put you in ball park.
Or, Use this,
http://www.calculatorsoup.com/calculators/math/ratios.php