Wanna discuss head balancing?

[cili]

I was wondering if some of ya'll might be interested in discussing how to balance mulching/mowing heads. I know there's a big difference in running a smooth head and an out of balance head for the operator not to mention the fatigue to equipment. Balancing heads was an up and down road for me through the years because of reasons we'll discuss. One time it would come in the next time it would make me pull my hair out. My limited experience was with rotors systems on helicopters which had turned out to be quite different than the mulching drums. With helicopters it's; static balance, pitch setting(blade tracking), lead/lag, and then forward flight balancing which was very challenging or so I thought. Unlike helicopters when trying to balance heads there were no charts or ANY kind of information to aid in knowing how to do it. Thankfully though now I'm some better and will share some hard learned lessons with ya'll if you like. For you who want to keep your heads smooth there's some rather cheap balancing equipment that you can purchase to do it yourselves. For most it's very intimidating at first but if you stay with it you'll get it.

 

[tonyoz]

Cheap balanceing equipment= 1 magnet,a set of scales, scrapmetal and a welder.:thumbsup::laughing::laughing::laughing:

 

[nwterex]

I'm interested

 

[QwikDraw]

Here's an old thread I started on balancing

http://www.tractorbynet.com/forums/land-clearing/167762-mulch-head-balancing.html

 

[cili]

Ok quickdraw, I didn't search through the old threads. It sounds like you got better equipment than mine but I am wondering does the analizer tell you which end to put weight? Mine only has one accelerometer (measures vibs per second) that you must move from one end of head to the other. One of the biggest problems I had was that I was use to balancing disc type rotating objects. I would get reading and it would tell me where to put weight. With drums like we have they MUST be looked at as two seperate rotating disc, in other words from the center of the drum to one end is one disc and from the center out to the other end is another disc. Most of the time if you look at or can feel each end of your head you will be able to tell which end is out. If the imbalance is dead center of the drum then you would either put weight somewhere around center or split it up and put the weights out at the ends at same clock angle. Now, so that we dont get confussed, let me say that when we talk about where in the rotation the weight needs to be it is called clock angle. You need to be thinking along the lines of the disc that I mentioned and see it as a clock as viewed from one end of the drum. You would have 2 "clocks", one for each end of the drum. My balancer has a photo sensor in which I put a piece of reflectant tape on one end (doesnt matter which end)of the drum,usually on a tooth and then clamp the sensor to the body in such away as necessary for it to read the tape. This lets the balancer know what clock angle the weight needs to be added and also reads rpms. You don't have to move this as with the accelerometer. Now I know most of you dont have this equipment so we'll try to keep this simple. Unfortunately without balancing equipment it'll take longer and probably not as smooth as it could be. You will basically be doing what curbside does in quickdraw's thread but with some of the info we talk about maybe we can figure a way to do it quicker, maybe. The above mentioned is the most important, knowing which end is out. Note too that if something like a tooth holder has broken off or the like then this will aid in determining where you will be working. Now if you can determine which end is out then one hurdle is done. I'll stop here to see if any questions are out there.

 

[tonyoz]

With one sensor you will only harmonically balance the rotor.You need 2 sensors so that the rotor can be dynamically balanced. If I have to change a tooth I also change the one on the opposite side and opposite end if it is out of balance

 

[cili]

Tonyoz, I'm sorry I didn't make it clear. I have one photo sensor that ony has to be somewhere to read the drum in rotation so as to let computer know which clock angle the drum is out. It can be read off shaft, pulley, or drum. The tape is 12:00. I also have one accelerometer that MUST be moved from one end to the other. This reads the vibration and with the photo sensor it's able to tell you where the imbalance is on the end that you have the accelerometer mounted. I have it fixed so that I clamp with vice grips to simplify moving. As discussed above you normally balance one end at a time. When I start a new balance on a new unbalanced head I have to move from end to end, would certainly be nice if I had 2 accelerometers.
Now the one thing I would strongly suggest is that everyone who wants to try to balance thier heads invest in a set of digital scales. You can get them fairly cheap at places like northern tool or harbor freight or where ever. They need to be able to weigh as much as the weight of a new tooth that goes on your head.
This is one reason why; if your head was smooth and you haven't lost a weight or got bad wear on a non-replaceable part of your drum you can simply(though it's a lot of work) add weight to each tooth to get it back to the orginal weight by welding (on the softer metal) or in some cases use washers. Make sure if you weld that it doesn't sacrifice the integrity of your tooth, in most cases I don't think it will but don't take my word for it. This will fix most balancing issues because most have differently worn teeth that are scattered across their head and rightfully so because of the cost.
I use to think that I could balance if I could equal the weight opposite(180 degrees) of a tooth that was worn bad or replaced new. It will usually make it better and sometimes make it within reasonable balance and that's fine (kinda what I think Tonyoz is doing). However it wasn't until my last balancing that a light went off in my weak mind that I finally found the missing link(so to speak). It answered the problem with why heads were out of balance without teeth or why if you had a lot of wear that you couldn't get a true balance. The problem is I don't know if I can explain it, maybe someone out there can but I will try a little later. To be simple and for the time being please understand that when a head is balanced it is balanced with new teeth and no wear(duh, I know) but when and if I can explain it, you will see that all weights and teeth need to be close to original weight to get the smoothest balance. Example; if you take a brand new head that's perfect balance and you take all the teeth off and put another set on that weighs 50 grams each less the head will be out of balance to some degree depending on the design. Now if your really into this I will futher say that IF you could remove 50 grams from the other side(180 degrees) of each one of these teeth it would not balance it. It would make it worse in most if not all cases. Getting kinda long so I'll stop here for a while to get replies.

 

[cili]

Ok, lets try to keep it simple and put what we've talked about in an understanding form, hopefully:thumbsup:. The 2 most common out of balance problems are;(1) differently worn teeth mixed across the head and (2) a holder or weight has broken off and one welded back on. If number 1 is your problem then the best way to balance (without purchacing balancing equipment) is to roll up your sleeves and get ready to work awhile or pay somebody. Get a set of scales and find out how much a new tooth weighs for your head. Then do whatever works to get each tooth back to original weight. You will find that washers are good weights. If it's impossible to weld on or bolt weights on to your teeth then it becomes a little more challenging, we'll get to that later. Some of you may be thinking that you can get a balancer and weld some weight to the drum in just a few minutes and bingo problem solved. No because then you are only fixing the "current" out of balance problem. Why? as soon as you start replacing teeth plus wearing continues on your right back out plus your complicating future balancing with those weights you had welded on. In other words it's a temporary fix and a future pain in the butt. Why, you have to keep in mind that with the arrangement of the teeth and other yet to be explained reasons each drum is it's own when it comes to balancing. The weights that were put on it when new plus the new teeth will never change unless something changes (which will be wear at least on all mulching heads) or something breaking off. Keep in mind too that some drums have weights and or tool holders that are susceptible to wear and these can't be unbolted. So in these cases you can build back with weld to try to get it back to what you think it was. This would probably get it to a decent balance unless there's a lot of wear in different places then you might want to get some balancing equipment to do a more accurate job. Now to go back to the challenge of not being able to build up the teeth or add weight to a bolt or the like. Some may come up with there own way and that's great. What I would do(if no balancer) is put the best (heaviest) teeth in the middle of the drum and work outwards in order of weight. For lack of a better explanation, think of your drum as a see-saw and your going to put your weights on it in such a way that the heavier ones are in the middle and they get lighter as you go out towards the end. Why? well it goes back to that unexplainable thing we hope to conquer:thumbsup:. What this will do is make it a little easier to trial & error the weight and it's placement. Then we would run up the head and see which end is vibrating the worst. We would then stop the head(duh) and place weight on the end that had worst vibs. Where and why? Well this is the good ole trail & error part. Just keep in mind that anything welded on needs to be done in such a way that it can be removed easily. I would use a weight that weighs about 100 to 150 grams and tack it(pretty good) on the opposite side(180 degrees) of the outter most tooth. Run it up again and see if it worse or better. NOTE, GET A PAD AND PENSIL so you can keep up with results of each run up. If better your probably within 60 degrees of where you need to be with weight placement. If worse then remove weight and place on other side(180 degrees). Run up again and observe the vib. again. If better then your probably within 60 degrees of weight placement.If you cant tell much difference then remove wt. and place it 90 degrees from that position and repeat. In other words the first position would be marked 12:00, the second 6:00, the third 3:00 or 9:00, and forth 9:00 or 3:00. Now if you find a smoother spot then you can remove wt. and place it at about 10 to 20 degrees forward or backwards in rotation to see if it gets better and you can add 50 grams or so at a time to see if it gets better. If the other end was out and I'm sure it was then do the same to it. If the end your working on stops getting better then you need to work on other end. Time for a break!

 

[cili]

I've attached a drawing to hopefully help aid in showing what I can't explain. The drawing is a drum with teeth(and holders) mounted along one side(odd numbers) and teeth(and holders) along the other side(180 degrees) from the odd. There's a segmented line to show center of drum. Now if you were to place this drum as is on a saw horse directly under center line it would be balanced. Agree? Sure because same weight on both ends and places along linear plane as it would be on a "see-saw". Well unfortanetly, when it's rotated It becomes a different situation. This is what had me screwed up so bad for a long time. You will notice I show the two places where weights would need to be placed for a dynamic balance. I'm sure there's someone that can explain the theories for this but it ain't me. The best I can explain it is as follows; tooth 8&9 counter weigh each other because they are close to opposite (180 degrees) of each other and very near center. Then as you move out, 6/7 and 10/11 (and so on) counter weigh each other till you get to the end and where there's no counter weight for 1 and 16. So to balance it you would need to weld a weight that weighed the same or more than likely a little less than the tooth and holder at the places shown. I know that most drums have the holders with teeth "scattered" around the drum which unfortanely makes it harder to see. This drawing is for clarity and simplicity I hope. When I talked earlier about how the head gets out of balance from wear and that trying to get it back in balance by simply trying to match balance teeth that are near opposite of each other like 4/3 or 2/3 for instance. It will help sometimes but if you study the drawing you will see how it will can never get it to perfect balance. When the weights are put on "new" they have to be a certain weight(duh) but as wear comes into play these weights in effect cause an imbalance. So you either have to buy a new set of teeth, build all the teeth back to original weight, or buy some balancing equipment to (temporarily) fix your imbalance from time to time. That's all I'll say on the subject apart fom questions. Good luck View attachment 252600