What about these for PCB drilling / routing?
Some have integrated electronics, and some are high speed and are continuously rated.
We also have torque curves.
There are verity of speeds and the datasheets do match, what you need to look at is the nominal speed not the max speed.
As an example there is a motor that has a max speed of 20000 RPM, but at that speed the torque is very low, but at 12000 RPM, the torque is at its highest and this is the speed we rate the motor at.
this is the misconception a lot of people have.
If a motor has a max speed of 20000 RPM, does not mean that you can get the most power at that speed because torque drops as speed goes up.
Shit? compared to what? The datasheet lists a no load speed, and surely you realize that this is not the rated speed of the motor?
Speed is propotional to Voltage and Torque is propotional to current, and the curve shows the continuous rating.
Just like other DC motors, you can get more torque at the higher speeds, but you will be limited due to heat, and the heat will effect the duty cycle.
When you buy a servo motor that has a nominal speed of 3000 RPM, but a max speed of 5000 RPM, do you call it a 5000 RPM motor, no you call it a servo motor.
Why? because the speed is varible, and not fixed.
Who said it was a 20000 RPM motor?
The description doesn’t, the specification only mentioned the no load speed.
In fact the motor is not a 12000 RPM motor, but it will do 12000 RPM continuous at the torque specified inthe torque curve, just like it will do 20000 RPM at the speed is shows in the curve.
The only person who made the misguided assumption that it was 20000 RPM was you, and then claimed it was crap becasue the power at 20000 RPM was not as you expected.
These motors have a variable speed and are designed to be used throughout this speed range, so the torque curves are there to show what you will get at a specific speed.
Show me an AC induction motor manufacture that offers a speed curve?
They don’t offer them because they rate their motors at a known speed.
When you buy a AC induction motor and you ask for a 2800 RPM motor they will sell you a 2 pole motor, but the speed may not be 2800 RPM, and generally varies by about 150 RPM due to slip, but this does not mean that the motor is faulty it is just the design of the motor.
Would you send it back if you were getting 2734 RPM if you run it at 50hz? no you wouldn’t.
You made the assumption not me, i was just pointing out your assumption was wrong.
Having started to look at bearings for high speed operations it looks like your burn out after a 100 hours may well be 'par for the course'. I looked at angular contact bearings with rated speeds of up to 200,000 rpm (phew!) and when you take into account preloading and cooling and lubricants and distortion of the shells due to centrifugal force, blah, blah, blah then 100 hours is 'par for the course'. Anyway back to the Dyson motor. If it contains bearings that will stand up to a 100 hours usage (which lets face it, for say a years warranty is ball park reasonable to expect) then maybe the motor is worth consideration.
All good stuff but it is speed I am looking at. A Dremel tops out at 33,000 rpm, no load, and I consider that a little pedestrian.
Ok so gear things up but using something like belt drives at high rpm involves tensioners and even then at high speeds perceived internet wisdom seems to think that belts stretch, slip, burn out, skip out of grooves, become unbalanced, 'become complicated'. Gears seem to suffer a similar perceived status of 'complicated'. At the moment my thinking is that direct drive is the way to go but I am still very much open to persuasion and/or reasoned argument
By dsc in forum Marketplace DiscussionReplies: 5Last Post: 23-07-2013, 10:54 PM
By njhussey in forum Tool & Tooling TechnologyReplies: 4Last Post: 04-12-2012, 07:07 PM
By Simon C in forum Motor Drivers & ControllersReplies: 5Last Post: 31-03-2011, 02:27 PM
FOR SALE: digital vernier.By i2i in forum Items For SaleReplies: 8Last Post: 13-08-2010, 10:31 AM
By Robin Hewitt in forum Milling Machines, Builds & ConversionsReplies: 14Last Post: 22-08-2008, 09:21 AM