Wheel balancer

Don't waste your money, we tried one for mobile work and it was completely useless. It's just a spirit level where the bubble sits inside of a circle, you just add weight to any part of the rim until you are bored.

"Fred" useless. It's just a spirit level where the bubble sits inside of a

Speaking of which, I can vaguely remember seeing on Tomorrow's World back in the 70s, a device for automagically balancing wheels. IIRC it was a circular piece of tube with ball bearings (about 6 or so 1cm diameter) and some fluid to damp things down a bit. If the wheel was perfectly balanced then the ball bearings would space themselves out equally as the wheel spun, but if the wheel was out of balance then the bearings would automagically adjust their spacing to compensate.

Yup I remember that. Always wondered why it never caught on

This sounds similar to what you mention:

I haven't ready it all but it seems to a describe a device for permanently fixing to the wheel to provide automatic balancing.

OK thanks. I'll give it a miss.

Certainly the description of the patents that he's trying to supercede. It does go on a bit though and I reached glazing over point about halfway down the page.

Dynamic balancing's really usefull. For angle grinders:-)

You got further than I did then, even with a £4k balancers you can still get a different reading if you take the wheel off and remount it. I remember they used to do a sit and ride balancer which balanced the wheel on the car, that was hopeless too.

Costco only charge 2.35 to rebalance a wheel, they use a several thousand pounds machine. Unless you are going into business, purchasing a wheel balancer is not worth it. A manual tyre changer is well worth having though !!

I've made a manual bead breaker and need to balancer to finish off the job.

£2.35 for balancing sounds good. Does that include taking them off the car and refitting them?? Kwikfit here are £5.25 whether they are on or off the car and 5 X £5.25 adds up to a figure that makes £70 seem OK for an occasionally used balancer - but not if it doesn't work.

The Costco price is drive in drive out, same if you take in a loose wheel.

I don't believe that a 70 quid balancer could work any better than a home version:. If you have a really free running, non driven hub then spin the wheel on there and see if it keeps stopping in the same place, if it does add some weight roughly opposite the heavy bit. This method works acceptably well, but is not as good as a proper spinning wheel dynamic balance. or get a spare hub from a breaker and use that.

I've used that method for years (- using an old hub with no brakes) and was happy with the results but now I've got wider wheels (205 instead of 145) and imagine results would be a bit variable as I wouldn't know which part of the rim - inside or outside to stick the weights and suppose it is more important with the wider rims.

Balancing using the hub seemed to be accurate to within a few gms. I find it hard to believe the £70 balancer would manage even that.

"Fred" useless. It's just a spirit level where the bubble sits inside of a

If it's designed correctly a bubble balancer should be a perfectly good method of balancing a wheel. It does depend on a number of things though.

1) Friction in the pivot which should be negligible if made properly. 2) The resolution of the bubble. These are made to different specs so that a given angle of tilt leads to a smaller or greater displacement of the bubble. They come in standard sizes and it doesn't cost much to change to a better one from a company such as..

3) The angle of divergence of the cone the wheel sits on. The shallower this is, and hence longer, the more accurately the wheel is located. With very shallow angles it might need more than one cone to suit the various sized wheel centre holes. 4) Burrs or other damage on the wheel centre hole or the cone. Throwing the wheel off centre by even a thou can lead to quite a lot of mass being incorrectly balanced. If you imagine a slice through a wheel and tyre only 1 thou thick that's still a fair amount of material. That's also why even professional balancers can only register as well as the wheel is mounted and that won't always be the same as it is on the car and will probably alter every time you put the same wheel on the balancer anyway.

As for balancing rim to rim rather than just in one plane with all the weights on one rim I haven't found this makes a scrap of difference on wheels of normal width. It's clearly more important as the item gets longer such as an engine crankshaft if a rocking couple is to be avoided. If you think about tyre wear, which is often eccentric if the tracking is out, if rim to rim balancing was necessary this ought to lead to a balance problem if the tread is scrubbed off on one side but doesn't seem to.

It did .. for 48x 52x .. CD players!

Speed variation of car wheel makes the ball bearings move round, either lagging under acceleration or leading when braking. Due to impulse from each power stroke there is constant vibration in transmission system, the primary damper being the tyre contact patch and tyre wall. Then there is road surface induced vibration. Ball bearings in real world car wheel balancer are in state of constant confusion. On CD player the CD is run up to speed and then held at that speed, once at constant speed with little or no external vibration the ball bearings soon stabilise it.

Mount hub on 2 pairs of thin strips of steel (spring steel would be best). The strips should be wide in axis of axle.

ASCII art (needs fixed font to view)

--- strips [ ]- hub & axle () tyre/wheel

--- --- () [ ]--

--- --- ()

Strips allow motion ^ ^ V V

Out of balance will make the whole assembly move laterally, side to side position of weight will make it waggle.

Delux model. Spin axle using belt from motor, fit motion detectors on each mount, fit index pulse gen / angle sensor on axle. Hook up to PC and get it to show where and how much weight is needed just like the ones tyre fitters use. Put it in a smart case with mounts for different wheels. Then you have a business!

I think I understand what you mean. Correct me if I've got it wrong, but I think you mean Have the axle supporting the hub and bearing assembly and the axle is supported on flexible strips so it is free to move laterally at either end. A perfectly balanced wheel would cause no movement of the axle and a balanced wheel with the weights at the wrong side of the rim would tend to make the axle point to left and right. If it was difficult to detect the difference between lateral movement and waggle, the wheel could be balanced first then the weights moved to minimize waggle. Perhaps a laser pointer could be attached to the axle to magnify the movement.

I've wondered how a balancing machine works - wondered if it has bearings for the shaft and load sensors at x number of spots round the bearings coupled with a device to record the impulses in relation to a point of rotation on the shaft. Extrapolating from your design here though, perhaps they'd only need one load sensor per bearing - or a motion detector as per your "deluxe" design.

Once I've found a hub I think I'll give it a try. Thanks for posting this.

Well the one I recently bought is a bit more refined :

Mind you as that cost £4k I may have a crack at your idea.

might be just as well to keep it out of site of your customers! (unless you put it inside a fancy case of course)

In the last year I have pulled apart around 150 CD-ROM drives to recover bits (for a children's robotics activity). I have never seen anything like this balancer ... where is it?

Ian