Poor man's rear wheel balancer - under $20

[TREE]

Here is a rig I built to balance the rear wheel and it seems to work fine.

 

http://tinyurl.com/7d5gu

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[TREE]

pix attached

 

Moditor edit: I put the picture in post for you

[No_Twilight]

well done. apparently you've been very careful to make sure your axle is centered in your rear wheel. Having a lathe I made one a little fancier. See attached. It is a copy of the parnes balancer with the following "Stephenson" upgrages:

 

1. Addition of a ring to allow horizontal clamping screws to ensure the cone is well seated in the wheel.

2. Dual angle cones to fit both BMW wheels.

3. O-rings near both ends of the axle to keep the bearing housing from falling off.

4. All screws have brass tips to keep from marring the precision shaft.

 

All fitups are w/in .001" which is indeed overkill. As for cost??? About 8 hours of fabrication. I had all the components in the shop--not a single trip to the store. I'm not sure that is a good thing.

 

moderator edit : pic in post here as well

 

 

Cheers,

Jerry

[Nevets]

Wow, a beautiful job. Shows some real engineering and craftsmanship. Ever think about selling them???? You and Mitch (with his tire bar) should go into buiness!

[TREE]

Very nice machining. I will probably turn one also when my buddy gets his lathe running.

[No_Twilight]

Wow, a beautiful job. Shows some real engineering and craftsmanship. Ever think about selling them???? You and Mitch (with his tire bar) should go into buiness!

 

I like to make things and sell them, especially with the ongoing divorce making me about $2k/month negative right now, but I couldn't market this one for a couple of reasons:

 

1. I stole most of the design from the Parnes balancer http://www.marcparnes.com/. He sells them and I like the design well enough to copy it. If you want some of my upgrades, I'd be glad to make those for you. I generally try to figure out what you would pay a machine shop for something and then charge half of that.

 

2. I've got probably 8 hours in this one doing the special touches that you do for something you're making for yourself. To make it cost effective to sell I'd possibly simplify it and it would look a lot like Marc's.

 

Thanks for the compliment,

Jerry

[David Sharpe]

How about a parts list and directions?

[No_Twilight]

How about a parts list and directions?

 

Looks like I've hijacked Tree's thread and I apologize. Tree, if you have any questions when you get ready to turn one, just let me know. And I thought of a way to double check the accuracy of the one you've already made: balance a wheel, take your adapter off and rotate it 180 degrees. Check the balance again. If it is still balanced, your balancer is going a great job and you don't need to make one like mine.

 

I didn't make any drawings, sketches, or plans. I just went to the garage and started work. Here is a detailed description of how I made it:

 

Shaft: 1/2" drill rod turned down to 12mm on the ends because I had a bunch of surplus 12mm bearings laying around. I then put an o-ring groove near each end of shaft with a 2mm parting tool. I played with the depth until the o-ring was fairly easy to slide the bearing over but kept the bearing from falling off. Oh yea, I centerdrilled both ends an put it between centers in the lathe. It had about .002" of runout in the middle. I straightened it with a rubber mallet on the bench (put a piece of delrin under each end and smack it with the bow up).

 

Bearing housings: All the aluminum is from a piece of 2" diameter scrap I had in the shop. I turned a pocket the depth of the bearing and about .002" smaller than the OD and then pressed them in. The center thru-hole is larger than the inner race to make sure it doesn't rub. I then milled a flat on the bottom of each one so it will sit on the jackstand. The bearings are standard 12mm id shielded zz. You could use 1/2" bearings and not have to turn down the shaft if you were buying bearings anyway. Then I would put two o-rings on each end for the bearing to sit between.

 

Cones: each cone has a 45 degree section in the small diameter area to match the chamfer on the front wheel bearing inner race. And each has a 30 degree section that matches the rear wheel better. Of course you want to bore the center hole and turn the cone w/o rechucking to ensure concentricity. I made a clutch collet 1.995" and about 3/16" deep to hold all the components so I made everything's OD 1.995". the clutch collet is much more convenient and much more accurate than using the chuck. I drilled the center hole 7/16 and then bored it out to about .5005". A solid carbide 5/16" boring bar is good for this task. I put two setscrews in one of the cones. You really only need one but by putting two in I endured balance wasn't affected. The other cone has no setscrews because it is pressed into place by the...

 

Pressure ring: To make it easy to ensure the cones are firmly against the wheel I turned an extra ring not included in the Parnes design. It just clamps onto the shaft with two thumbscrews and then has two horizontal screws to jack the cone into the wheel.

 

Screws: I took 1" long 1/4-20 ss capscrews and put Shur-loc press-on knobs on them except for the to horizontal ones. The Shur-loc knobs would have hit the shaft so I turned a couple of knobs out of brass. Again, I just went by a size and shape that looked good to me. I drilled them a couple of thousandths smaller than the head of the screw, knurled them, and pressed them onto the screws. I put brass tips one all the screws as follows: I chucked the screw in a 1/4" 5c collet with the head inside the collet. It is long enough to stick thru. Turn the end flat and then use a centerdrill to drill a hole in the middle. I think I used a number 4 center drill and the hole was about .128" and about .180" deep. I did about 12 screws this way in a production line effort keeping my setup between screws and it went very fast. Then I took some 3/16" brass and turned a nipple on the end .130" x 160". I parted them all off the same length, about .100" as I recall, so they would all weigh the same. Actually I made the brass tips first and while the screw was still in the collet I pressed the brass tip in with the tailstock and deburred the cornersand used the centerdrill to put a dent in the middle to ensure there was no litle tip in the center from the parting tool. Sounds more complicated than it is. I made a dozen of them in less than an hour. I'll attach a photo. I can't figure out how to embed it.

 

I think this is all the details. Feel free to post or PM me with questions. I would apologize to the non-machinists for the long explanation but they quit reading long ago.

 

Cheers,

Jerry

[TREE]

Looks like I've hijacked Tree's thread and I apologize. Tree, if you have any questions when you get ready to turn one, just let me know. And I thought of a way to double check the accuracy of the one you've already made: balance a wheel, take your adapter off and rotate it 180 degrees. Check the balance again. If it is still balanced, your balancer is going a great job and you don't need to make one like mine.

 

No problem Jerry, always nice to get more info.

 

I think the secret with my cheapy is to check the radial runout before you balance the wheel.

 

If it is running on a true centre the runout should be very small and balancing after that should be accurate.

[RFW]

Here is a rig I built to balance the rear wheel and it seems to work fine.

Here's a tip. Remove the shields from the bearings, and clean all the grease out using a strong solvent such as lacquer thinner. Then spray a copious amount of WD40 in the bearings.

 

The purpose of this is to eliminate the rotational resistance caused by the grease.

 

I made a balancing stand simiar to what you show, except is was welded from square tubing and the hub was machined from a big chunk of aluminum. But the results are no doubt much the same. There was a noticeable improvement in the ease of achieving balance when I did the WD40 trick,.

 

Bob.

[flatbutt]

how well does this compare to a dynamic balancing?

[TREE]

Nothing compares to dynamic balancing if you look at the physics.

I'm lazy, the rear often runs with no weights and still feels fine.

I still prefer to dynamic balance the front though.

Almost never do the rear dynamically, only static.

[No_Twilight]

I've read just the opposite, that the dynamic balancing used by the shop is designed for speed rather than accuracy and you can take a shop-balanced wheel home and improve it with one of these manual balancers. --jerry

[SWB]

I've read just the opposite, that the dynamic balancing used by the shop is designed for speed rather than accuracy and you can take a shop-balanced wheel home and improve it with one of these manual balancers. --jerry

 

I've read the problem in dynamic balancing is in how well tuned the equipment is. I guess in a lot of shops either the equipment isn't maintained well, or the technicians aren't trained well, with poor results to the customer. For that reason, I kind of like to balance my own as well. But the home made stuff I used was crap compared to these illustrations.

[RFW]

how well does this compare to a dynamic balancing?

Dynamic balancing is essentially irrelivant on a motorcycle wheel. It is needed on car wheels because they are wide compared to their diameter, and an imbalance can also impart an axial "rocking" motion to the wheel.

 

With a bike wheel, it is so narrow as compared to its diameter, significant dynamic imbalance is not possible, so only a static balance is sufficient. If a rotating disk with zero thickness is statically balanced, then it is by definition also dynamically balanced, since it has only 2 dimensions (no axial thickness). A bike wheel essentially acts nearly like a zero-thickness disk, so dynamic balancing is pointless.

 

It is wise nonetheless when adding weights, to remember not to put them all on one side of the rim; they should be divided up so roughly equal half are on side, and the other half are right opposite on the other side.

 

Bob.

[No_Twilight]

how well does this compare to a dynamic balancing?

Dynamic balancing is essentially irrelivant on a motorcycle wheel. It is needed on car wheels because they are wide compared to their diameter, and an imbalance can also impart an axial "rocking" motion to the wheel.

 

With a bike wheel, it is so narrow as compared to its diameter, significant dynamic imbalance is not possible, so only a static balance is sufficient. If a rotating disk with zero thickness is statically balanced, then it is by definition also dynamically balanced, since it has only 2 dimensions (no axial thickness). A bike wheel essentially acts nearly like a zero-thickness disk, so dynamic balancing is pointless.

 

It is wise nonetheless when adding weights, to remember not to put them all on one side of the rim; they should be divided up so roughly equal half are on side, and the other half are right opposite on the other side.

 

Bob.

 

Bob,

What you have described is the difference between 1 plane and 2 plane balancing. INdeed the static balancers that we build are one plane. Most dynamic balancers used to balance car tires are indeed two plane balancers. I looked at a lot of balancer literature on the internet and "dynamic" and "two plane" seem to be used incorrectly as interchangeable. Dynamic, in this case, means spinning. Static means stationary. I'm pretty sure that the relatively inexpensive dynamic balancers used in motorcycle shops are single plane balancers, for the reasons that you explain very clearly.

 

So the question is, given that both the static and dynamic balancers for motorcycle tires are single plane, which machine does the best job. I still say that the dynamic balancers are designed to give an acceptable job in a quick time (production mentality). I'll eventually find someone with a freshly mounted tire from a shop to put on my static balancer. I believe my balancer will show detectable unbalance. Not that this is a real problem. We've been using wheels balanced as well as the dynamic balancers do the job for years, going 160+ mph occasionally, with no problems.

 

--Jerry

[RFW]

So the question is, given that both the static and dynamic balancers for motorcycle tires are single plane, which machine does the best job. I still say that the dynamic balancers are designed to give an acceptable job in a quick time (production mentality). I'll eventually find someone with a freshly mounted tire from a shop to put on my static balancer. I believe my balancer will show detectable unbalance. Not that this is a real problem. We've been using wheels balanced as well as the dynamic balancers do the job for years, going 160+ mph occasionally, with no problems.

You are quite right. I WAS getting "dynamic" and "2-plane" balancers mixed up. That's probably because so-called "dynamic balancers" used for cars are also 2 plane types as well. A dynamic balancer just spins up the wheel and then as it spins figures out where the weight needs to be added. This is a much faster process than spinning it by hand and waiting to see where the heavy spot is as the wheel stops.

 

So the main advantage with a dynamic balancer would appear to be to speed up the balancing process. As you say, ordinary static balancing works perfectly well if it is done with care (and the static balancer's bearings are really friction-free). I do my own; it takes about 15 minutes per wheel to get it right, but even at 200 km/h it appears rock solid.

 

Bob.

[No_Twilight]

 

Bob,

So far I'm working on theory only since I haven't balanced a single tire. But my balancer feels Smoooothe....To minimize friction, I used a 12mm shieled bearing. (6301 ZZ). The sheilded bearings seem to have less grease friction than the rubber sealed ones and the slightly smaller bearings (others use 1/2") have slightly less friction. Someone suggested using open bearings and I considered it but didn't want to deal with dust/dirt. One dirt spec and the wheel will tend to stop there. If I find that my bearings aren't loose enough I'll heat them before use. Grease gets pretty running about 120 deg F.

 

Thanks,

Jerry

[TREE]

Nothing compares to dynamic balancing if you look at the physics.

I'm lazy, the rear often runs with no weights and still feels fine.

I still prefer to dynamic balance the front though.

Almost never do the rear dynamically, only static.

 

After reading all your good comments I will modify the post above......

 

Since I built the front wheel balancer I must admit I have not paid for another dynamic balance although I used to prefer it.

 

I find doing a static balance at home on the front works just as well and I have had no problems.

 

The rear I will first run it with no weights to see if I can feel anything. So far on all the wheels (8) I have not been able to feel any imbalance. Maybe your butts are more sensitive but it seems that once the rear is locked up to that rear drive the point becomes moot.

 

This project was a rainy day boredom experiment, and it was fun. I balanced the rear, it took one ounce, then I removed it and ran it up to 75mph and the rear still felt smooth.

 

That's my story and I'm sticking to it............

[Green RT]

I also built my own. Pictures below. The only comment on some of the posts so far is that I am skeptical of some of the bearing schemes. You want fairly low friction. I used a couple of pulleys to support each end of the shaft. You can also just roll the shaft on a couple of level knife edges.

 

The plywood stand and pulleys were cheap. I had a machinist make up the shaft and cones for about $100 or more (I don't remember exactly).

 

The larger cone is for the rear wheel.

 

I have used this gadget for quite awhile.

 

 

 

[RFW]

The sheilded bearings seem to have less grease friction than the rubber sealed ones and the slightly smaller bearings (others use 1/2") have slightly less friction. Someone suggested using open bearings and I considered it but didn't want to deal with dust/dirt. One dirt spec and the wheel will tend to stop there. If I find that my bearings aren't loose enough I'll heat them before use. Grease gets pretty running about 120 deg F

 

That's because the shield in a shielded bearing does not touch the inner race. As for removing the grease, I had suggested this in a previous post. I did just this (after removing the shields), and sprayed WD40 in the bearing instead. It markedly reduced the friction. I had no real problem with dirt entry, but if it does happen, all you need to do is give it a shot of WD40 and spin the bearing. It will run smoothly after that. It's a lot less inconvenient than getting out the old blowtorch

 

Bob.