Rebuilding trackballs

[_) (V) (-)]

Hey guys,
I just scored a box of some VERY used trackballs and was hoping to piece together something usable from the lot. There are  a couple Happs type, one says Atari, and a couple Imp's, however, most of these seem to be beyond resurrection. (Hence the reason I got them)

The first thing I noticed was most of the balls appear to be loose in their housings. Some by 1/8" or more.  This does not seem normal. Is there any way to repair this?

I was thinking of shimming up the bearings or maybe putting a liner over the roller surface. Currently experimenting with some plastic tubing.

Also, some of the rollers actually have a groove worn into the center where the ball contacts it. I dunno if anything can be done for this situation.

Something else I thought about, was shaving off some of the underside from the top case piece, thus making it sit lower and closer to the ball.
Is that a valid option?  Of course the circuit boards would need to be trimmed a bit as well if they are to fit into their places.

I'll also need to find out how to test the circuit boards without anything to plug them into. (other than a DVOM) Not sure what 'lingo' to google even. Man I'm ignorant!

Figure it should generate some kind of pulse to coinside with the veins on the shutter wheel thingy. I'm guessing a light voltage with a high and lo limit.

Can anyone recomend a good primer (for dummies) on rebuilding these things?

Thanks!
_)

[divemaster127]

Purchase one of the happ rebuild kits with bearings & rebuild the trackball
dm

[_) (V) (-)]

That sounds too simple to be true DM.
The bearings actually seem to be fine. At least they move nice and smoothly, they are also clean and oiled.

Will the rebuild kit address the sloppy fit issue?
Do the balls ever shrink?

[Texasmame]

Do the balls ever shrink?

 

[shardian]

I have put new rollers in a 3", and it really didn't seem to help the slop much. It made no sense to me either.

[Fozzy The Bear]

Balls do slop around in trackballs.... It's not a fault... They work by just sitting on top of the rollers. They shouldn't be at all close tollerance to the case.

As long as your rollers and bearings are good to go, and the balls are not chiped or damaged then they should be fine.

Best Regards,
Julian (Fozzy The Bear)

[Dudeman]

Do the balls ever shrink?

 

Shrinkage usually occurs when swimming in cold water. Just ask Costanza.

[RayB]

The grooves in the rollers are part of the reason why the ball sits lower. Replace the rollers.  And yes, it is as simple as that EXCEPT they aren't cheap!!

Another thing to check is if you have any Wico TBs you'll find they have little springs under the bearings. That's supposed to help keep the ball close to the opening lip (but still not touching it).

[_) (V) (-)]

Well guys, I've been playing with my balls alot recently. . .
and I have found that the white one is in fact smaller than the red one,
by about 1/16 of an inch.  (Maybe it's infected?) 

I've swapped them from case to case and found the difference in fit is related to the ball and not the casings or the rollers. Then I verified it with a micrometer measurment. Shame too because I really wanted to use the white one in my setup but dislike the sloppy feel.

I tried putting a piece of plastic tubing over the rollers in one of the cases just to see how it would do. It did in fact raise the ball height, however the plastic surface was not optimal for traction. It was actually a little too sticky in some directions, not wanting to move. Maybe a metal sleeve would work better? 

RayB, only 1 roller in each of the 2 larger 3" trackballs were worn in this fashion. The ones I've been experimenting with (2 1/8") have no groves in them. Didn't see any springs in the 3" wicos, but there was some kind of green wire with a copper strip on the end, looks like it could have gone under the bearings. Is that the spring you mentioned?

[shardian]

Have you considered raising the bearings in their seats with something. You could gain an 1/8" easy that way.

[_) (V) (-)]

Yes Sharidan, and that is a really good idea, but the problem is that there are portions of the top casing that actually hold the bearings down into their slots, attempting to keep them 'level' with the top edge of the lower casing.  I didn't want to modify the casings any but, it may not be that big of a deal. I've got a couple to work with here.  I'd really like to clean up the action on this thing before I cut up my control panel and install it.
Guess I have to do something cuz I just don't like touching sloppy balls!
 
(hey, someone had to say it)

[RayB]

No, the green wire is just a ground.

Maybe someone put a billiards cue ball of the wrong size in there. It should be 2 1/4".

[_) (V) (-)]

Ya'kno, it does look like a cue ball, but it was just a typo, I ment to say (I mean type) 2 1/4" there.

The size difference is very small, like 1/16th of an inch. But it is enough to make the thing hop around in the casing if you really get on it.

[shardian]

Where would you get a cue-ball of non-regulation size anyways??? Reg. is 2-1/4"

[_) (V) (-)]

eBay?
They got everything else . . .

[u_rebelscum]

Where would you get a cue-ball of non-regulation size anyways??? Reg. is 2-1/4"

Probably a cue ball for coin operated pool tables.  The way the table "knows" to return a cue ball scrach but not the numbered balls is for the ball to be different size (usually).  Most often the ball is bigger (2-7/16" or 2-3/8"), but there are smaller ones too (2-3/16").  (IIRC, sometimes the coin cue ball weighs differently instead of size, but this is rare AFAIK.)

I've seen these coin cue balls at sports stores.

[shardian]

Here is a quick article that explains coin-op cue balls.

it will be bigger than a regulation, not smaller.
http://www.straightdope.com/mailbag/mcueball.html

[Jess--]

it will be bigger than a regulation, not smaller

unless its a UK cue ball, 95% are smaller here

[_) (V) (-)]

I have no idea where my balls have been but I do know 'Shardian's shimming suggestion' (patent pending) has been most helpful.

I cut the clear tubing off the rollers and used pieces of it to raise the bearings up in their seats, then took a small grinder and removed a bit from each of the spots on the top cover part that was intended to hold them into place. After a few trys I got everything to fit together again and the slop has been reduced to about 1/16". I'd say about 70% better. This I can live with, Thanks for the tip!

Also worked up a mouse hack and used it as a testing rig to go through all the rest of these. Most are actually working fine. Found a couple that appear to have flakey sensors or diodes but overall I'd say I have enough parts to get 4 out of 7 up and running. 

Now I need to score some trackball mounting plates. Anyone have a few they'd care to sell or trade?

[shardian]

Glad to be of service.