TopHat Report post Posted August 3, 2018 So Juki makes these motors, J7R KE120 series, that appear to be digitally controlled brushless motors. Would these be worth an upgrade over a FamilySew servo motor? I know these have an option to add synchronization and all that, but I'm wondering if these things have a better "braking" action when paired with a speed reducer (which increases torque) or any other benefits. Quote Share this post Link to post Share on other sites
brmax Report post Posted August 3, 2018 Trying to grasp what you might need braking for and to understand better your question. In that servos, in their basic operation can expend a lot of watts to maintain a stop or in its run scenario under a load. They continously try to meet a target in a closed loop, or just continous. I really wished I could write code in some advanced way. Especialy with the motors i have now. All that has to include some equipment to analyze the outcome. So if these motors are the voltage you can use and a wattage of equal or higher its sure possibile to be a nice option motor. But without a bit more information I cannot agree its a needed change. Good day Floyd Quote Share this post Link to post Share on other sites
Constabulary Report post Posted August 3, 2018 (edited) Reg braking power - I figured (and i only have experience with JACK Servo Motors from College sewing) that the 750W Motors have a harder / stronger brake than the 550W motors. I put a 550W motor on friends a Adler 105 and I have a 750w Motor on my Singer 45D91 (both machines are the same class). The 750w motor makes a bit more noise but when you step off the pedal its a much harder stop compared with the 550W motor. My friends machine does stop but you can see that the needle still makes some way when you step off the pedal (if you know what I mean). These are the servos from College Sewing, they have a separate control box and accelerator unit https://www.college-sewing.co.uk/store/Jack-Servo-Motors The one you show looks like a "budget" servo you find on Ebay for below 100€ - they have a combined control box and accelerator unit! https://www.ebay.de/itm/220V-550W-Brushless-Motor-Servomotor-Nahmotor-Fur-Industrielle-Nahmaschine/273220104265?hash=item3f9d2ff049:g:ii8AAOSwrY9a~jgD Be careful - read the details - these motors (not sure if its the same as the Juki but looks like it is) start at 500 RPM (!!!!) most other Servo Motors start at 200 RPM - that is an important detail I think! Edited August 3, 2018 by Constabulary Quote Share this post Link to post Share on other sites
dikman Report post Posted August 3, 2018 From Wiki - " The advantages of a brushless motor over brushed motors are high power to weight ratio, high speed, and electronic control". Which means they should be a bit more efficient than a brush motor, but honestly I doubt if, in the case of our needs, we would notice any difference. The main advantage I can see is that there are no brushes to wear out (but again, for most of us I doubt if that's likely to be a problem). As for "braking action" I doubt if they'll stop any quicker than the common brush motors many are using now - at least not enough that we're likely to notice it. Only reason I could see to change is if you wanted the "latest and greatest" , but I would also assume that they would come at a premium cost. Quote Share this post Link to post Share on other sites
DrmCa Report post Posted August 3, 2018 I am surprised by how tiny the motor is, about 1/2 the size of Family. Can it really deliver the same HP? Quote Share this post Link to post Share on other sites
brmax Report post Posted August 3, 2018 It is suprising the size of these anymore. I have seen inside several and most are this very same size, though shrouded in various housing styles. Many have a circuit board and or three. Good day Floyd Quote Share this post Link to post Share on other sites
