Picture Of Machine.
Picture of machine.
Re: Counter Weight Problem
ScreenGuy,
The weight of the counterweights required will be equal to:
m = (M x r) / R
where
m = required total weight of all counterweights in pounds
M = total vibrating weight of screen (basket + mechanism + effective material load) in pounds
r = the required radius of vibration in inches
R = the radius from centre line of the mechanism shaft to the centre of gravity of the counterweight in inches
For example:
Let’s assume that the total weight to be vibrated is say 3000 lbs, and that the desired radius of vibration is 0.125” (0.25” dia).
Furthermore let’s assume that the centre of gravity of the counterweights will be say 4” from the centreline of the shaft.
Then the total weight of counterweights required will be = (3000 x 0.125) / 4 = 93.75 pounds ■
Man That Is Awesome
That is simple enough for me to use. Thanks a lot.
I just tried my first weight (10 lbs. set at 4 inches off and centered on the shaft) and it bent my shaft (1.5" round bar). The bearings were set apart at about 50". I could not believe it. THe whole machine tried to vibrate off the ground. The ami bearings seemed like they were going to come apart. I thought it was dangerous so I bit the bullet and block a set of pillow block extra duty bearings at $250 each. I also upgraded to a 1 15/16 shaft size with the bearings being set at 30" apart. I then put the weight closer to the shaft 2" or so off and spread it along the shaft instead of one large piece.
The machine is acutally running awesome now, with about 15 lbs or so of weight.
I am not sure but It seems that it might be "throwing" in the wrong direction and since my great design used one screen dumping large debris to one side and then the smaller screen going the opposite way. I am not sure this can be done.
I have not added the screens yet but I noticed my clamps went uphill instead of down and off to the ground.
Can I have 2 screens inclined in different directions on the same vibrating unit?
Will it work?
I notice that my wieght amount is low for 800 pounds, according to the formula so I might need to add more.
I will test it first.
Thanks for the help ■
Screaming Screener
About your screener,
Bear with me here as I only want to help you:
opposing screens have been done but require a lot of work, timing and balance as the orbits would cancel each other out
You need to take a 12 quart pail of the material and raise it to your shoulders
and flip it over in one quick movement the resulting angle is the angle the screen should be to screen the material- its and old tyler screening method but it works for inclined screens.
An easier less troublesome method to screen material is with a near flat screener at a very low angle.
You can take all the steel you have and reuse it to make a flat screener that you will never have to shake like an elliptical screen
A wide long screen deck will give you good separation with a flat screener-you wll just have to dump slowly to avoid overloading or meter the material with an an auger with a small dump hopper which are easy to find and buy. the thing is you can dump an entire bucket of material in the small hopper and the auger meters the material to the screener and avoids overloading and screen blinding.
The longer flat screener will allow you to have several screening cuts from smaller to larger as it moves back and forth on the same deck screen box as well with no issues at a very low angle of departure at 10 degrees and a short stroke length with no issues of balance and excess ellipitical orbit which is but one of many reasons why your shaft bent.
The screening box will be carried by steel wheels on bronze bushings stub shafts which are supporting the entire side of the screener riding in two pieces of channel iron-so if you have a single twelve foot deck or longer the length does not matter.
You just need to buy enough wheels to allow full support of the box and deck when you are dumping so you should have at least 4 on a side equidistant along the length of both sides to aid in the screening process.
You can reuse the pillow blocks and any good shaft stock for the rotating twin cam discs at the end of the screen box and the arms that would be connected to the cam discs and to the screen box at the bottom at each corner with bronze bushings and greased to allow easy movement.
You could use a tractor PTO shaft to spin the cam discs from the engine shaft through a v belt drive off to one side to aid in its moving when needed
and you will never run out of torque to move the screen box either as the wheels are always moving because of the rotation by the discs and the reciprocation created by the arms attached to the discs.
Or use a right angle gear box at the bottom of the frame with the pto shaft to spin the cam discs as you will only need a 30-40 rpm at the cam disc to move the screen box or less per minute and short stroke distance of 4 inches nearly horizontally and screen a lot of material with several cuts of screns in one deck
I would advise you to substitute air bags for the coil springs if you intend on using your weldments as they will amplify the excitation if they become compressed to the point where they are over loaded with the weight of the material being screened and coil springs will break(been there done that because they refused to substitute air bags to eliminate the vibration problems on an 8 by 16 screen- they added weight under the screen to cancel out the resonance created in the 1,000 plus tons of steel in the screen plant because the manufacturer told them to do to that way, and I was the stupid one. lots ostress cracks in that mess and the steel work.
You can simply add air pressure to the air bags and leave them sealed to absorb the impact of the material on the screens with no issues also. ■
Any Progress Update On Advise??
is it working........as the mad scientist would ask?? ■
Good Results So Far.
Sorry for the delayed post I have been welding on the screener and crusher for the last 2 months and I have been so busy teaching my self how to make new things. My Screener is working as planned, just not as fast as I want but it works. I have learned much more since my last post and appreciate the advice. The screens move material each way with no problems and I love the first screen as it gets rid of most roots medium to large rocks sticks trash etc.
Points for others.
1. Cross supports under the screen cause material to build up and slows the movement down the screen.
2. My Vibration is weak when screen is heavily loaded need larger weight to slow the spin down and increase the shake. The bearing and shaft get so hot you can not even touch it. I am wondering how long my six hundred dollar bearings are going to last . (working on larger counter weight now.)
3. I should have made the screen tighten by bending the mesh up on the sides then pulling it tight with angle iron and bolts. I elected to bolt it down flat to save two metal break fees$$. So... it could be more efficient. with less material on and under the screen slowing flow.
4. If soil is not dried properly it will gum the screen up. When the soil is dry it works so much better.
My screen classifies 3 sizes. The items that stay on the 2nd screen are what I am after. Dirt loves to ball up and stay on the screen. This really bothered me so I figured the easiest way to break the dirt was with a roller crusher system. Which I made.
The crusher is quite interesting to watch work. It is good and dangerous. It will turn rocks to dust up to about 3/4 of an inch in size. The crusher / conveyer took some work figuring out pulleys to rpm then pulleys to fpm. My plan was to place the crusher under the screener by digging out the ground with the loader. This did not work out so well. I realized that I needed a conveyer belt to run the material back up so gravity could do its thing through the crusher.
The conveyer is foldable so that it folds up and out of the way for transportation. It runs from about 60 to 150 FPM. About 75 or so FPM I like the best, it is safer and works the crusher better. I made the bottom roller adjustable for tensions on both sides to help with the tracking of the belt. It is still being a pain in butt. When the screen loads up heavy , the belt gets a lot of material which makes it heavy. It will move to the side and bind so I am still working out the bugs in it. But it works about 50% so I can test my system some what.
Once the material goes though the crusher I am still left with small sticks, roots, glass, and whatever else is the small enough to go through the crusher and still stay on the screen for the 2nd pass. Also some dirt and wood chips? just will not go away.
Any of you guys got any ideas on how to use air to blow the light weight stuff off? I was thinking of using a home air conditioner fan setup with baffles and/or spinning air in a chamber? I am looking for a cheap and easy way to seperate heaiver material from lighter material similar in size with out using water. I know, I know what you are thinking this guy is cheap!! I am so way over budget on this project. Three motors, 4000 lbs of metal, 250.00 in welding rods, 2 months of 10 to 12 hour days.
Regards, ■
Major Set Back. The Welds And Steel Are Breaking.
Well after 10 hours of heavy use, my screener is breaking. I doubled the weight in the shaker assembly to about 25 lbs or so. This allowed me to slow the speed of the spinning weight which allows the bearings to run cooler and it gives harder/stronger shake which seemed to be perfect. Wet clay will stick some so I ran the RPMs up and it moves along but it balls up some. About 1 hr of this and it broke.
At first a few welds on my steel drop funnels broke. Which I fixed. Then Today the screen got very loud and I noticed that the main angle iron that holds the screen on both sides broke.
The angle iron is 3/8 steel 4" x 4" angle. So the L works as a base for the screen to attach to and the side holds the material on the screen. The top leg or the metal that runs up and down spilt down both sides of the frame near where the weight frame assembly attaches to the angle which is in the center of the angle. The bottom part of the angle has not broken into yet so the deck stayed together. The breaks could be due to it flexing in an up and down motion or it could be the vibration is going into the deck at this point and this area is over stressed. Do I need more support from vibrating unit to the shaker deck?
Any one have any ideas? I was thinking of reinforcing the shaker deck angle with 1/2 flat bar on the veritcal sides to transfer the engery further along the angle but I am not so sure. The forces that are occuring are so strong.
Or could my problem be the distance between the springs which are set to the ends? 8' feet apart. Should 3/8 angle hold up or is it to small for this stress?
Near where the angle broke a vertical 3/8s thick steel angle 2 x 2 runs from the top deck to the bottom deck. This has the weight attached to it. So this angle sends the vibration into both the upper and lower deck. ON the lower deck it is sending it into the center of the angle iron support rails. Where my breaks occured. You can see this in my picture above.
What should I look at to fix my problem. Just add more steel or is my design bad? ■
Bad Design....Further Complicated By...
with full respect: I must tell you, you are somewhat re-inventing the wheel here. Especially if you are screening clayey topsoil, non-free flowing material.
I read all posts again and am shuddering somewhat as I read due to the use of the words WELDING....(heat checks created), cracking (caused by heat checks caused by welding...= break), adding weights.....speeding up.....operating at most likely now..at TOO HIGH of accelerating forces or G FORCE to keep your hard worked on design together. ((WHEN you start to WELD TO FIX on these frames YOU ARE basically done in my opinion....unless you can control you welding heat or self relief those welds after welding.....it will just keep re-breaking)
All of these issues are NOT NEW to screening of material at all but, rules must be followed or these vibrating units WILL self destruct and that is what yours is in fact doing.
THE bearings...i do not believe are calculated.....properly...for what we call L10 Bearing life....so they are most likely UNDERSIZE and the wrong type for vibrating screen duty. Vibrating screens typically utilize wide 33 series type double spherical roller bearing type bearings by SKF, TORRINGTON, FAG typically....they are built to take the operating forces created by the operation of vibrating screeners.
GET YOUR hands on a VSMA book for starters...for all the answers to all of these types of issues....not expensive and very very informative and helpful. I will try to PDF your some troubleshooting pages for your use.
ALTERNATIVELY, buy a used vibrating screener that will do thee parameters of the actual JOB you want it to do.....and save a lot of money....and screen what you need to screen. FILL in a vibrating screen questionnaire first to decide what issues MR VIBRATING SCREEN needs to deal with first before you buy a used one.
GOOD LUCK. George Baker - Moderator ■
Vsma Pages For Help
Vsma Pages
Check these vsma sheets for help. Enjoy. Gb
Attachments
■
Vibrating Screen Principles.
AN interesting link to help you.......ENJOY....GEORGE
http://www.pitandquarry.com/educatio...r-14-screening ■
Vsma Troubleshooting Tips And Guidelines
HOPE this helps.....it is actually quite quite proper and it does identify nicely, typical problems with vibrating screen breakdowns.
enjoy. George Baker - Moderator
Attachments
vsma problems&solutions chap 9 titlepg (PDF)
■
Check With Manufacturer...Kinda Marked With Asteric
I have worked for over 30 years with vibrating screen mfrs...the reason VSMA marks that at the bottom of each page is quite important.
EACH mfr has his or her own AS built MANUFACTURING BILL OF MATERIALS.....very very important before ...say speeding up, slowing down, adding or subtracting wgts, static wgts......dynamic operating wgts, weight of screen cloth, rubber, perf, or urethane.
They like people to check ...because when they build up the TOTAL STATIC weight of whatever the vibrating screen box is going to end up at......THEN, and only then do the engineers....calculate the size of the shaft that is needed diameter wise, the offset needed to move the static weight of that AS BUILT WEIGHT, and the size of bearings needed to actually run the machine and get what is considered a reasonable, bearing life out of the unit.....typically want minimum 10,000 plus operating hours (L-10). if they do not get acceptable bearing life.....it is quite often back to the drawing board to design a better mousetrap that will.
hoping this might be of assistance .......George Baker. Moderator ■
Vsma Page 9 Sizing Bed Depth Calculation
In my travels, i find almost everyone and their brother are semi comfortable sizing a vibrating screen, if you are in this business.
BUT, i also find almost all folks, except for people who actually work for companies that make vibrating equipment MISS THIS LAST VERY IMPORTANT SIZING DOUBLE CHECK.
most just go with what the SIZING FORMULA pukes out....whether that be, VSMA or some company's own formula. and DO FORGET the last bit, to do the BED DEPTH CALC.
say the formula gives you a 120 sq ft of screen area needed for example: a 6x20 for example....right? NO....or maybe no.
at this point we apply bed depth calc and EXPERIENCE of customer's actual weather conditions, material conditions, past machine size used experience, whether the machine was TOO BIG OR TOO SMALL, whether there was carryover or not of fines or whatever....we apply the BLACK ART, EXPERIENCE OR knowledge. and who knows you may BUMP THE SIZE UP TO 7 x 20 or because of that.
Im just saying.......... keep smiling.... George. ■
Hi George, Thanks For The Info. Better Results.
George,
Thank you for getting me the info that you posted. I have not seen that before.
Since failure is not option I did the only thing that I could still do without dissambly. I added more support. Based on my results which was from field use, I decided to reinforce the vibrating unit attachment to the shaker deck. I went to the local scrap yard and located the largest rebar I have ever held. 1" plus. There was a lot of it and it was cheap. I also got some thick walled sqaure pipe. All told i spent $36.00. At this point it could have been $250 million. Every dollar more it cost me it really gets me upset. I need results. And I got them for only $36 dollars more.
I then welded as many triangles As i could get from the shaker to the deck. And from the upper to lower deck. All told I added about 150lbs of bracing and used triple + welds with 7018 5/32 rods. I repaired the broken angles and added more steel to the vibrating assembly to further reinforce it and spread the forces. This sends the vibration forces in sort of a circle into the frame work at more than four locations. 8 total. This spread the forces in many different directions and upon more of the steel.
So far I have had success. The unit is more balanced and it really shakes nicely. It almost goes into what I call a sweet spot and it runs. I have used it for hours on end now with no broken welds or cracked steel pieces. Other than the skid steer attachment points which broke with the machine about 4 feet off the ground. I have really learned a good looking weld might be crap. I now know how to control the heat as well as the bubble gum so to speak.
When the machine hit the ground the vibrating deck which I guess weights about 800 lbs bounced up into the air and broke my engine and bent the springs. I repaired the motor and set the tray back down on the springs which straightend them back out some. I am willing to bet my unit will out perform most made commerical small top soil screeners out there. It will power through dump truck after dump truck load of dirt. I base my statement on u tube videos of others equipment. My 2500 lb machine was made according to my needs. Which was 3 main things. 1. Overall weight. Unit must be able to be moved along with a skid steer to the job site and it must be able to be moved around site with the skid steer. 2. It must handle the dirt moving ability of the skid steer with out much fuss. 3. It must fit on my trailer with the skid steer without needing a new trailer. It has met or exceeded my design requirements. It is robust and can be hit with the skid steer and still operate. It will withstand moderate abuse. It will handle and sort off large rocks roots and other debris. It screens well.
The design was simply and it is really works better now that I have been able to fix the faults. I am not sure how long it will last but I will keep you guys updated if anything comes loose or If any one has questions on how to make your own.
Welds will hold if you can set them thickly and smoothly, spreading the heat widely. They will amost have a smooth look with nickel on nickel type consistancy. It was hard to do and i had to do it 3 different times with many passes. But it holds. I also found out that you should not run the machine long empty, keep weight in it to dampen the vibration. We the machine is loaded it might have 500 to 1000 pounds on it so that in itself can change how it runs.
All told I have two months of work in the design and making of this machine. It cost me 1/20th the cost of a commerically made unit and I have pride for the orginal design of which I have not seen any others even come close to making. I can load and unload this machine in less than 5 mins. I can start it with the turn of a key. I love watching the large and medium rock roll right of the end of the unit. I have not be able to get one stuck yet! One thing that I have noticed is that most of the screening is done in the first foot of the screen on the second deck. It seems as if the dirt just falls right through and not much happens after that. so strange to watch. It is like a waterfall of dirt.
Thanks Again for the help.
ScreenGuy ■
Thanks So Much For Your Update
Wishing great success.......let us know how it all ends.
Sincerely,
George Baker ■
Counter Weight Problem
Counter weight amount and how do you make a stroke?
I am new here and I hope that someone can pass along a little help.
I have been working on making my home made screener and I am in the process of designing the counter weight for my stroke and throw.
My machine weights 2000 lbs and the vibrating assembly weights about 450 pounds. It will need to handle half a skid steer 6' wide bucket load of dirt or so at a time as it is partly dumped on to the top screen (maybe 400 to 650 pounds at a time). Georgia dirt clay top soil.
I plan to use 1.5 expanded metal for the top screen which will shed larger debris to one side using a 23* slope.
On the lower screen it will shake smaller debris to that end using a heavy 1/4 wire cloth at 12.5* angle.
Motor is an 11 hp gas engine.
It will use to pulleys to power the weight shaft which is center in the screen trays center point of gravity. It will hold the counter weight which will be centered on the shaft, not on each end and it will be adjustable in LBS.
This is my first project.
I know you guys get real technical here, I am not that techincal I just need a little direction in about how much weight I should start with. I plan to spin it at about 1000 rpms which will be a little adjustable with the fuel lever on the gas engine.
Can someone give me a starting weight to try and how far away from my spinning shaft it should sit.?
Thanks.
Will include a picture if I can figure out how to up load it. ■