Any tips for opening a 130 size DC motor case? - Page 1
Forum section: electronics / beginners

author: gsgx
author_rank: Contributor
timestamp: July 25, 2023, 07:17:05 am
content: I'm trying to open a 130 size DC motor to fix one of the brushes inside. The problem is there are two metal tabs that keep the plastic casing closed. The width of the tab is about 2.5mm, and the smallest prying tool I have is 5mm. I tried a 2.5mm screwdriver, but I think the head is too thick to actually get under the tab.On YouTube I saw someone pry it open with scissors (which didn't work for me) and a soldering iron tip (which I don't to do as I don't want to damage my tip).I can't find any inexpensive tools online that seem like they would work here, does anyone have any suggestions for how I can get this thing open?

author: Zero999
author_rank: Super Contributor
timestamp: July 25, 2023, 07:31:33 am
content: Why do you want to open it up? Prefumably for educational purposes? Those cheap motors are not worth repairing.I've always managed to do it with a small screwdriver. Try multimeter probes.Note there might be some grease on the bearings, which should be kept out of the brushes, otherwise it'll burn, shortening their life.

author: beanflying
author_rank: Super Contributor
timestamp: July 25, 2023, 08:14:40 am
content: Try searching for O'Ring Picks. The good ones have a T handle on top which allow good control of the point.On the smaller ones go slow and carefully taking the back plates off or you will bend the brush holders and cause more damage than can be fixed.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 25, 2023, 01:14:16 pm
content: Seems like a silly thing to want to do.These toy motors are quite cheap, and they won't last long anyway.It's multiple things that fail, bot the brushes and commutator, and the bearings ain't great either.It's just not worth repairing, just get a new replacement motor.

author: Zero999
author_rank: Super Contributor
timestamp: July 25, 2023, 01:32:40 pm
content: Quote from: Doctorandus_P on July 25, 2023, 01:14:16 pmI agree about it not being worth repairing, but not that it's a silly thing to do. One of the first things I did as a child was open up one of those motors, fix it and put it back together. The stranded wire I used to replace the brush with, didn't last long, but I learned a bit from the experiance. It's not something I'd do as an adult, unless it was to diagnose why it failed, or show it to my nephew.

author: CaptDon
author_rank: Super Contributor
timestamp: July 25, 2023, 03:08:49 pm
content: Shirley you can't be serious.....Are you kidding me??? What do you have around the house? A dental pick, a jeweler's screwdriver, a long small nail, a sacraficial screw driver to be narrowed on a grinder. Use your imagination. I was ripping these things apart when I was about 6 probably with a sea scout knife. A hammer will work if you are in a ward with no sharp objects allowed.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 25, 2023, 04:20:44 pm
content: Quote from: Zero999 on July 25, 2023, 01:32:40 pmTaking it apart with the intention of repairing it is a silly thing to do.Taking it apart with the intention to look inside how it works, analyze it's (crappy) quality or other reasons is very valid and can be eduactional.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: July 25, 2023, 05:49:48 pm
content: Small side cutters/dykes.

author: themadhippy
author_rank: Super Contributor
timestamp: July 25, 2023, 05:59:37 pm
content: give it to a small child with instructions not to open it

author: gsgx
author_rank: Contributor
timestamp: July 25, 2023, 07:40:30 pm
content: If I'm being really honest, the fact that I'm unable to open it is the main reason I want to open itThanks for the suggestions, will go to a hardware store soon and see what I can find.

author: Nusa
author_rank: Super Contributor
timestamp: July 25, 2023, 07:52:47 pm
content: Do you have a corkscrew? Or a fork? Both of those should have a good enough point for the job.

author: Gyro
author_rank: Super Contributor
timestamp: July 25, 2023, 08:23:27 pm
content: Quote from: themadhippy on July 25, 2023, 05:59:37 pmI was opening folded tab motors like that when Iwasa child! They always succumb to tool misuse (usually sidecutters).

author: gsgx
author_rank: Contributor
timestamp: July 25, 2023, 09:21:45 pm
content: FWIW, today I tried side cutters as well as a multimeter probe. Neither can get a good hold between the tab and the case, so they slip.

author: coppercone2
author_rank: Super Contributor
timestamp: July 25, 2023, 09:53:43 pm
content: don't pry with scissors or do anything with scissors, don't even try to slide open a cardboard box. For some reason they really like hurting you when used improperly.Like seriously its the worst tool for prying. I feel like for some reason I feel safer with a big ass knife then a scissors. At least the knife is solid.What might work is soldering some crap to the tab of the motor, and gripping that with pliers, then removing the solder after you bend it out. Hahah I hate those fucking things, I think at this point if I had a hard one I would spot weld something to it so I have a grip point. At least I won't be the ass hole damaging flush side cuttersyour co workers would borrow your side cutters to open that tab.

author: amyk
author_rank: Super Contributor
timestamp: July 26, 2023, 12:17:08 am
content: Have opened and cleaned/greased many of these; needlenose pliers with suitably serrated jaws work well. Put one jaw behind the tab and the other one on the side of the case where the tab begins to bend, push down and rotate outwards.

author: johansen
author_rank: Super Contributor
timestamp: July 26, 2023, 03:30:08 am
content: Quote from: themadhippy on July 25, 2023, 05:59:37 pmI think i was around 7 when i started taking things like those motors apart. Think i tried to rewind one of them when i was maybe 9.

author: beanflying
author_rank: Super Contributor
timestamp: July 26, 2023, 04:08:29 am
content: And some of us have never lost the joy in taking stuff apart even as we ageI spent a chunk of my 20-30's extracting and abusing Mabuchi 480's in R/C Aircraft for a specific race class. As part of the Brush break in process we actually ran them for extended duration at low voltage underwater. Yes that was a thinghttps://www.wattflyer.com/forums/showthread.php?t=5788&page=2So much easier now than then with brushless.

author: Infraviolet
author_rank: Super Contributor
timestamp: July 26, 2023, 09:10:33 pm
content: I'd give an extra note for serated needle nose pliers, use them to bend up the metal tabs, then use them to tug on the white plastic so as to pull it out. Given my experience looking inside failed motors of similar type I'd say the plastic will need quite a lot of tugging to come out, the tabs aren't the only thing holding it in, there is a strong friction fit between the plastic back cap and the metal casing.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: July 26, 2023, 09:44:22 pm
content: This looks like one of the more challenging ones to open. The tabs are in deep wells in the end cap, and though the picture isn't clear enough to be sure it appears that much of the end is swaged down around the cap.I would recommend you buy some cheap small screwdrivers, either new or from garage sales and the like. Grind one or more down to get the widths and shapes you need. Either grind slowly and cool the tip with water regularly or be prepared to reharden and re-temper the end after you do this. Scribes and picks can also be useful. Once the prying tools have done the job of getting some clearance between the parts a small set of needle nose pliers is useful. Here good quality is appropriate since they will be worked hard.Since these motors are made in a few million sizes (well only a couple of hundred nominally size 130) and windings it can be tough finding a suitable replacement. Which sometimes makes repair more worthwhile. Particularly in toys where the repair will often last long enough for the child to grow out of the toy.

author: MarkS
author_rank: Unknown
timestamp: July 26, 2023, 09:58:17 pm
content: I've always used a sharp, pointed knife. Steak knives work well. However, I've never been able to get them to run correctly after putting them back together and God help you if they didn't epoxy in the permanent magnets! There's really nothing of note inside. Typically, it's just two magnets (of no particular use due to the curvature, a tiny copper wire wound rotor and a couple of finger style brass or copper brushes.

author: Zero999
author_rank: Super Contributor
timestamp: July 26, 2023, 10:10:14 pm
content: Quote from: MarkS on July 26, 2023, 09:58:17 pmI've never had a problem. I don't think I've seen a small motor like the one in the original post with the magnets glued in place. They're secured in place with a U-spring, with holes punched in the other side, with the metal pushed in to form flaps.I think the issue you probably have is you're damaging the bushes. The trick is push the shaft downwards, whilst removing the armature, so the commutator doesn't separate from the brushes. Then, when putting it back together, hold the armature so the commutator pushes downward, so it isn't sucked in by the magnets.

author: MarkS
author_rank: Unknown
timestamp: July 26, 2023, 11:58:00 pm
content: Quote from: Zero999 on July 26, 2023, 10:10:14 pmI haven't opened one in about 30 years, but I do distinctly remember some with glued in magnets. Good point about the brushes! That brought back a memory. Yes, that was the problem. I could never put it back together without damaging them.