Trying to get stator machined for learning project need advice - Page 1
Forum section: electronics / projects

author: fahraynk
author_rank: Newbie
timestamp: September 09, 2016, 01:47:47 am
content: Hi. I am trying to figure out how to get a stator and rotor manufactured for a motor I am building as a learning project. Anyone have any clue how I can get a stator manufactured from a cad drawing with electrical steel ?Everything I see on the net is for large orders sigh. I have never done this before so I figured id ask for help. Am I going to have to make the stator myself or is it easy to find someone to machine it?

author: alsetalokin4017
author_rank: Super Contributor
timestamp: September 09, 2016, 02:38:25 am
content: Step 1: Buy a case of beer and chill it down.Step 2: Go to your local Makerspace or small automotive machine shop and look for a machinist to befriend.Step 3: Apply beer liberally.Step 4: Break out the CAD drawings and start negotiating....

author: DaJMasta
author_rank: Super Contributor
timestamp: September 09, 2016, 03:25:54 am
content: While the above advice is solid, maybe try to find a hobbyist or enthusiast with access to a machine shop but who doesn't do it for a living. If you can get them interested in the project or offer a nice reward, it could be an interesting one-off thing for someone who just wants to try stuff out. Maybe a technical university of some sort would have a prof. that could recommend a promising student for an interesting side project.Just ideas, but there are definitely people who enjoy doing it and have some access to good equipment (or can use it as an excuse to get access to better equipment!) and that enthusiasm could go a long way for keeping a one-off prototype project in a reasonable budget - could also mean a friend or go-to machinist for future ideas!

author: Jeff_Birt
author_rank: Regular Contributor
timestamp: September 09, 2016, 03:50:12 am
content: The type of steel used for laminations is nearly impossible to get in small quantities. I know there are companies that make specialty motors who will laser cut the laminations for you, as we have had them made at the university where I work. I'll see if I can find out some names. Your choice of lamination thickness is limited to what is commonly produced and what the company cutting them for you has in stock.Also keep in mind that total thickness of your stack of laminations will be different than what you think. Lets say you want to use 50 layers of 0.5mm laminations and some simple math would say that 50x0.5mm=25mm. The lamination stock will actually be 0.5mm+- some amount and when the laminations are cut imperfections to the edges are introduced so when you stack them up you 50 laminations might actually be 26.2mm. In practice you build a fixture that compresses the laminations and you add as many as you can to get as close as you can to the total lamination thickness the design calls for. Then you weld the edges of the laminations. This can be done with a TIG welder doing a fusion weld, i.e. no filter material.If your design uses any sort of commutator or slip rings that adds more fun but is straightforward machining. If you are designing a brushless motor with a PM rotor it can be hard to find the curved magnets for the rotor in the size you want so you may have to wrap your design around the magnets you can get. Gluing magnets to an armature is tricky. There is a special type of CA (super glue) for that purpose you can get from McMaster-Carr. You may need a special fixture to hold the magnets in alignment as you glue them as well.For the case you may be able to design around using a standard heavy wall tubing. What I have had to do I start with a thick wall tubing and bore it out or start with a sold rod and drill/bore it out. For a 'pancake' brushless motor I built I first 3D printed the case which was accurate enough to fit the rotor and bearings and the stator lamination stack and give the student designing the motor the opportunity to workout the final details or how to get the wires out, and after he wound the stator to make sure it still fit the case! Then the case was machined out of two 1"x6"x6" pieces of aluminum.Even a small motor could take from two day to two weeks of machining time. Half or more of the machinist time of R&D projects is just spent figuring out how to machine the part, creating fixture and setting a job up. I have spent 10 times as long on the planning, fixture, setup as it took to machine some things. Do not be surprised if the machinist suggest other ways to accomplish what you have in mind, in fact ask for their opinion. I get designs all of the time that can't be manufactured, can't be manufactured on the machinery I have or are far more complex than they need to be. I have found that talking with the student, professor, etc. and talking about the design allows us to come up with a plan that is more likely to work.