Need help finding a bearing for a motor! HP 113BR frequency divider and clock - Page 1
Forum section: electronics / projects

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: July 06, 2021, 03:18:50 am
content: I'm repairing an HP 113BR clock. It's a 1961 vintage mechanical clock driven by a motor whose speed is controlled by a 100Khz frequency standard input to the unit. The rear bearing on the motor is shot and the manual does not break down the motor that far.I'd like to replace both the front and rear bearings but so far I can't find a substitute. Without my micrometer handy it looks like the shaft diameter is 1/4", the bearing O.D. is 15/16", and the thickness is close to 7/32". I can mike it tomorrow to verify but that is very close. Can anyone help me source this item?Any help will be appreciated!Cheers,Corby

author: edpalmer42
author_rank: Super Contributor
timestamp: July 06, 2021, 03:47:36 am
content: The two good sources of bearings that I know of are:https://www.mcmaster.com/bearings/ball-bearings/https://www.wmberg.com/products/bearings/bearingsBut I don't see anything close to your measurements. Get out your magnifying glass and look at the bearing really closely. I have bearings that are smaller than yours and they're marked with a part number. Do you have a manual for the 113BR? They usually give a part number and manufacturer in the parts list.Edit:Out of curiosity I checked to see if I could find any info on the small bearings that I've got. Add another company to the list:https://www.nhbb.com/products/miniature-instrument-ball-bearings

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: July 06, 2021, 04:00:43 am
content: Ed,The manual gives bearing numbers for several other bearings but not the 2 motor bearings.Also the bearings have no visible markings.I'll doublecheck tomorrow when I mike the bearing.Thanks!Cheers,Corby

author: mzzj
author_rank: Super Contributor
timestamp: July 06, 2021, 08:53:47 am
content: ID/OD ratio doesn't sound like any standard bearing and very few bearings come with 15/16" ODMany US manufacturers have used metric ball bearing sizes for historic reasons.Metric 636 bearing would be ballpark similar size but if you already measured your bearings with anything better than ruler its unlikely to match.

author: jpanhalt
author_rank: Super Contributor
timestamp: July 06, 2021, 09:10:20 am
content: Is it a ball bearing or plain sleeve, like oilite?If the latter, you may find a proper fit, but usually I just buy something close and turn or ream it to fit. If you can get the proper ID, turning the OD and adjusting the length is a little easier.

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: July 06, 2021, 05:40:04 pm
content: Here is a PIX.ID .25"OD .942"thickness .188"Extended thickness .218"Cheers,Corby

author: jpanhalt
author_rank: Super Contributor
timestamp: July 06, 2021, 06:26:25 pm
content: Just looking at that shield, I suspect the balls do not go from the OD of the inner race to the ID of the outer shell. It looks to me as if it is a relatively standar bearing for a 0.25" shaft pressed into something ( e.g., a donut) with the proper OD and ID corresponding to the OD of the bearing would work.

author: mikerj
author_rank: Super Contributor
timestamp: July 06, 2021, 06:42:10 pm
content: It's something like a R188ZZ in a spacer/bushing to extend the OD. You need to see if you can extract the bearing to be able to reuse the outer part, if not seems like a relatively simple part to get machined.

author: Gyro
author_rank: Super Contributor
timestamp: July 06, 2021, 07:04:44 pm
content: If the bearing does have a separate outer race, then it must be very thin - all I can see is the circlip that holds the dust shield, it's normally possible to see the outer race around that. If so, it's pretty unusual.As mikerj says, It should be pretty easy to machine a couple or rings to allow normal bearings to be used.

author: edpalmer42
author_rank: Super Contributor
timestamp: July 06, 2021, 07:08:01 pm
content: How fast does the motor spin? Does the bearing have to be anything special or would a generic ball bearing do the job?

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: July 06, 2021, 08:49:45 pm
content: The motor spins at 1000 RPM and the motor is mounted horizontally. The shaft that the motor drives spins easily and does not require a large torque.I'll see if I can get the old bearing apart so as to use the outer race as a mount for a smaller diameter bearing.Cheers,Corby

author: BrianInTexas
author_rank: Contributor
timestamp: July 06, 2021, 09:13:52 pm
content: The picture looks to me that the circlip holds the entire bearing within the bushing.If so, the bearing is not likely press fitted, and it will be possible to measure the OD directly.If the shaft is 0.25, the OD is likely 0.375.

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: July 06, 2021, 10:55:58 pm
content: Took the clips off and the two shields.Can see the ball bearings now!Flushed it out with WD40 and it spins nicely now.I'm thinking I'll re-grease it, reassemble and try it out.If that does not work I'll regroup!Any idea what kind of grease to use?I'd like to use something I could find at NAPA auto, in a small tube maybe?Cheers,Corby

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: July 07, 2021, 05:12:41 am
content: jpanhalt - I was told, by a mechanical engineer many years ago, that it was not recommended to ream an oilite-type bush. They are sintered and reaming tends to close the 'gaps' - in effect 'smearing' the material and creating a tube that is not lubricated. I seem to remember that it was not recommended to lubricate the bushes either, but I have totally ignored that during my working and hobby life!BT

author: james_s
author_rank: Super Contributor
timestamp: July 07, 2021, 05:16:57 am
content: I'm guessing the bearings are probably fine. I'd probably try something like WD-40 to flush out the old grease and then if they spin nicely put a few drops of light machine oil in there, the stuff sold as electric motor oil or sewing machine oil ought to work. If you do need to replace the bearings pretty much any machine shop ought to be able to make you a set of spacers you can press standard bearings into.

author: jpanhalt
author_rank: Super Contributor
timestamp: July 07, 2021, 09:42:07 am
content: Quote from: BurningTantalum on July 07, 2021, 05:12:41 amCorrect. I should have said better instead of easier. (In reality, I can't remember a time when I couldn't find the proper ID.) Oilite are supposedly pre oiled, but some sintered bronze used to come with a need to soak. In either case, like you, I oil both.

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: July 07, 2021, 04:11:38 pm
content: Here are PIX of the "guts".If the re-lube does not work I'll pull the guts and use a different OD bearing as suggested.The rear bearing has lots of room to kludge a different bearing.Cheers,Corby

author: BrokenYugo
author_rank: Super Contributor
timestamp: July 07, 2021, 05:20:27 pm
content: With such a small bearing I hesitate to suggest ordinary #2 GC-LB chassis/wheel bearing grease. Something thinner is probably (#0 I'd guess) more appropriate, but difficult to aquire in small quantities.

author: james_s
author_rank: Super Contributor
timestamp: July 07, 2021, 09:13:48 pm
content: Most small bearings use oil, not grease. Sewing machine oil or 3-in-1 ought to be fine. It's not rocket science, this is a 1,000 RPM motor, not turbomachinery.

author: edpalmer42
author_rank: Super Contributor
timestamp: July 07, 2021, 10:00:34 pm
content: Corby,Is this the unit thatnormallyruns so noisy that it practically drives you out of the room?You know you have to post a video of it working, right?

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: July 08, 2021, 12:17:40 am
content: Ed, It was SUPER noisy with the bad bearing!Once the motor was removed the input shaft of the clock moves smoothly and quietly so hopeful that it will quiet down a lot! I'll see about a video.Well cleaning and repacking the bearing did not work!The bearing is worn inside and allows the shaft to have several degrees of movement!This causes the rotor to rub.The front bearing is an order of magnitude better.I've ordered an R188-2Z bearing and I think I can make it work.Probably be a week or so before I have any further info.Cheers,Corby