How to attach a disk to the shaft of a small DC motor? - Page 1
Forum section: electronics / beginners

author: David_
author_rank: Contributor
timestamp: April 08, 2019, 11:06:26 pm
content: Hello.I have spent a lot of time taking any device I can get my hands on apart scavanging any intresting parts found inside, this has lead me to have aquired a small bag full of small DC motors, 6V, 9V and 12V motors.They all appear to have a shaft that is round and approximately 2mm in diameter and completely smooth, some of the motors have plastic parts stuck to the shaft but those plastic parts would have to be removed in order to make the motor usable for me.But I can't use any of these motors because I have no idea about how to find a product that can attach things to the shafts of these sort of motors.I have seen very suitable things that have a screw that is screwed into the side of the shaft going through a structure which then supports other things but I have only seen pictures of these and I can't find out what such a thing is called or where such components may be bought(preferably in Europe or from seller that can ship to Europe while not requiring a shipping cost far higher than the cost of the items).I have read online where people suggest everything from epoxy, loctite, filing a bit of the shaft flat to then be used with some mystery thing to attach stuff.Although I have a specific project in mind(a magnetic stirrer) I am looking for a solution that I can use many times.On a China made magnetic stirrer that I bought they use a DC motor and on the shaft there is a metal plate with a circular chunk of brass attached to the plate in the middle, the motor shaft goes through the plate and the brass chunk, then a machine or tool have been used to deform the brass to make a tight fit sort of as hammering in a nail a little into the brass and then removing the nail.Does anyone know of any source for parts that are used for these purposes?Or other repeatable solution?What I ultimately want in the project this I have in mind right now is to mount a couple of strong magnets onto the shaft, which would require a plate or disk mounted on the shaft to which the magnets can be mounted on to.Regards

author: Psi
author_rank: Super Contributor
timestamp: April 08, 2019, 11:10:03 pm
content: Use a joint coupler.This 2.2mm might work, but finding one designed for 2mm would be better.https://www.ebay.com/itm/Joint-Coupler-2-2mm-To-2-3mm-Brass-Couplings-Flex-Collet-For-Brushless-Motor-RC-/201866965246Ones intended for a smooth shaft will usually have multiple grub screws where as ones for a D shaft only need 1 grub screw to lock into the flat.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 08, 2019, 11:26:30 pm
content: The couplers as mentioned by Psi usually do not go much smaller as 4mm.The small motors with thin axles usually have very high RPM, which makes balancing important, and stuff like brass gears are usually press fit on the axles, which is not easy to do with diy methods.Easiest DIY method is probably to drill a hole in a small piece of hardwood and glue it to the shaft, and glue the magnets to the wood.Those press fit small pinions can be removed with tools like:https://www.aliexpress.com/wholesale?SearchText=motor+pinion+gear+puller

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 09, 2019, 03:01:17 am
content: A collet is another way of fastening to a shaft. Model airplane vendors carry sizes appropriate for very small shafts.The type of device you originally described is called a collar. McMaster-Carr carries them in metric sizes down to 2 mm and Imperial sizes down to 1/64 inch (about 0.5 mm). I guess metric isn't better for every thing.

author: beanflying
author_rank: Super Contributor
timestamp: April 09, 2019, 03:20:03 am
content: As CatilinaWOW mentioned R/C prop collets would be a good option. All you need then is a disc with your magnets. The benefit of a collet style over a grub screw held adapter is generally the radial accuracy for lower wobble or vibration. We virtually stopped using grub screw mounts a very long time ago on anything remotely performance.Plenty of good places online as sources Hobbyking would be one but more local to you will make it faster.https://hobbyking.com/en_us/catalogsearch/result/?cat=&q=collets

author: amyk
author_rank: Super Contributor
timestamp: April 09, 2019, 11:45:13 am
content: For a 2mm diameter shaft, press fit is the usual way to attach something.

author: CJay
author_rank: Super Contributor
timestamp: April 09, 2019, 12:03:14 pm
content: Quote from: amyk on April 09, 2019, 11:45:13 amAnd there's a large range of plastic press fit gears, wheels etc. available from model maker supply shops, sites likehttps://mindsetsonline.co.uk/and loads of other STEM resource sites

author: zynb.masm
author_rank: Newbie
timestamp: August 20, 2024, 09:09:01 am
content: Himy bachelor's project at the university is about building a magnetic stirrer. Could you please tell me how you connected the motor shaft to the magnet holder?thanks

author: CatalinaWOW
author_rank: Super Contributor
timestamp: August 20, 2024, 02:26:43 pm
content: Read the thread. Several suitable answers are given.Since you are at university to learn, I would suggest thinking about each of the answers and thinking about why each one might be more suitable for your (or any) application.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 20, 2024, 02:46:18 pm
content: You can buy things like this on Amazon (although this particular range only goes down to 3mm). If you've got access to a lathe you can make a bush for them easily enough.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 20, 2024, 02:49:01 pm
content: Quote from: zynb.masm on August 20, 2024, 09:09:01 amI'm with CatalinaWOW on this: if you're on a degree course you must learn to think for yourself. You've had more than enough advice - it's over to you now.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 20, 2024, 03:06:56 pm
content: If you don't want to order and wait, then improvise a coupler out of any item that might fit the diameter, random examples:https://www.instructables.com/DIY-PCB-Drill/https://youtube.com/watch?v=YE6L4-79bR0

author: Terry Bites
author_rank: Super Contributor
timestamp: August 20, 2024, 03:59:49 pm
content: A flange?This kind of thing:https://www.ebay.co.uk/itm/314366419074(cheaper on aliexpress)

author: SteveThackery
author_rank: Super Contributor
timestamp: August 20, 2024, 06:14:17 pm
content: @Terry Bites: I've just suggested the very same thing three messages earlier!