Apr 28

Swapping out J3 motor

4 comments

Hi Chris/all,

 

I've hit a weight limit with Axis 3 (it is skipping steps).

 

I'm looking at ways to reduce the total load by changing out tools but tomorrow I'm going to check if I can swap out the J3 Nema 17 motor with a J2 Nema 23 motor for some extra oompf.

 

I've done some quick measurements and at first glance it seems like a nema 23 might fit the frame but wanted to run it by you before I dig into too much.

 

Does this seem like a reasonable idea? And do you know if there is clearance for the Nema 23 motor?

 

PS: As an update I have finished installing the AR2 upside down (inverted). It has been hanging for a few days now and is doing great. I had to flip some of the motor directions as you mentioned but it went off pretty damn smooth all things considered. Will post some more information later.

 

P.S.S: I've also run it at a higher amperage which I will experiment with further tomorrow. It gets a bit more power but have you experimented with increasing the amp's over the specified?

 

 

 

 

I suppose the only concern I would have with using a nema 23 motor for J3 would be having to come up with a new motor mount to fit the nema23 drive to the robot arm. I think it should fit. the other thing is finding a sprocket with the larger 12mm bore. theres room under the cover for a larger sprocket you would just have to recalculate your total steps traveled. You can turn up the amperage to get more power just keep an eye on your motor temp. They shouldn't get hot enough that its too hot to touch.

Apr 29

Awesome, thanks Chris for the feedback.

 

I've ordered the sprocket & motor and will let you know how it goes. As it is inverted I'm not too concerned about adding the extra weight to axis 2 but will let you know how it all goes regardless.

 

I've also increased the amps to J3 and it is managing fine. I've got a few meters of cable which, with the help of an online calculator, adds ~5% of power loss.

Awesome, let me know when you can post some pics. Im very interested to see your project.

Apr 30

@Chris Annin Will do. And thank you for the feedback. I've got the Nema 23 motor on order and a low profile gripper.

 

As a note to others, I am running the J3 motor at 2.37A against the rated 1.68A (and the 1.46A default). It doesn't give an 'huge' power boost however is is noticeable but does generate extra heat. I've temporarily strapped on some small aluminium heatsinks which work surprisingly well to take away the extra heat.

 

I've seen folks online use small fans to actively cool steppers which would likely increase the power capacity.

New Posts
  • I read the build manual for the AR3 robot and found that during the build for the control box there is nowhere in the BOM does it mention the 5v PSU used in the build. Any specific PSU you'd recommend or any 5v PSU will work?
  • Hey Chris, is there a minimum screen resolution for ARCS? it wont dynamically adjust to my screen size that is 1366x768.
  • Hi Chris, I've purchased all the parts to upgrade my AR2 to AR3 but have run into a issue right at the start. Your AR3 Robot Manuel shows additional mounting holes for the encoders on the back of the steppers. My steppers do not have additional mounting holes in the back. I'm assuming that I need to drill/tap these myself? I don't see anywhere in the instructions where it directs me to do this... I'm also confused on the length of the shaft out the back... mine all seem short. The instructions included with the encoder are pretty basic and do not really help to solve this issue. Thanks!