aviphysics

Just thinking, this part doesn't have to be a full cylinder. It could be a 'C' profile, so that it can clip on with the machine in place.

I got the new metal worm and gear in today. The worm is just a little bigger outer diameter. More importantly the gear is a lot thicker than your design is designed to accommodate (though the diameter is good.) The good news is that the metal worm seems to mesh well with the acetal worm gear and doesn't require modification of the stepper shaft, so I will use that for now. To adapt the MK8 drive gear ID to fit the 3 mm shaft, I printed a spacer with an interference fit. I then put it in a little hot water and push it onto the shaft and into the sprocket. It took a couple of tries before I got one that came out really nicely. A little epoxy binds the worm gear to the drive gear. BTW, in the model on youmagine, the bearing holes do not seem quite size right for the 10 mm bearings. I solved this problem with a 10 mm reamer. Once everything is working, I have plans to do a little tweaking to make the design fit my metal worm gear and maybe tweak the bearing holes. For now, it looks ok.

Nice idea. Thanks

I really wish they would do something to reduce the number of clicks to reach the forums section. On mobile, navigating the forums currently feels like a massive PITA, especially when your connection is week. I would also like higher contrast delineation between stuff (like between posts and quotes inset in posts.) Currently, on mobile, everything kind of blends together.

On the Android version of Chrome, clicking "last" will sometimes take me to a page that says there are no replies.

Thanks. Looks like they ship to the U.S., so I will keep them in mind, if things don't work out with the gear from aliexpress.

What are the dimensions of your worm and worm gear? I was browsing what else is available and it seems like there is some variance. For example. This worm gear set is labeled as 0.5 module with a 1:40 ratio and the worm is available with a 4mm ID, but it seems like the diameter of the worm and gear are slightly to large for your design. http://www.aliexpress.com/item/0-5-modulus-wormwheel-large-reduction-ratio-1-40-remote-control-toy-steering-copper-worm-gear/32285575729.html My Acetal set on the other hand appears to have a spacing of about 12 mm from center of the worm to center of the gear. This appears to be what you designed for.

I am guessing that the blue box is the stepper motor. Not sure what the orange is and while I see the pulley I don't see the mechanism to hold it in place. Looks like the difference wouldn't be noticed in the original (non magnetic) modular head design, due to the difference width of the linear bearings. Still, looks interesting. At some point I will probably want to switch, and I already have almost enough parts to make 2 (would just need to order more bearings). On the topic of size, It looks like you used 10 mm OD bearing for the drive axle. Was there a reason you didn't use much smaller ones? Seems like 6mm OD is fairly common for a 3mm ID bearing. Edit: It actually looks like 9mm OD is what your design used. Couldn't find that locally, so I went with 10 mm and made the holes slightly bigger.

Why does the filament diameter have such a big impact on how big the extruder is? Is it just a matter of the required gear ratio?

The current plan is to visit a friend with a metal lathe and try to turn down the shaft. If that does't work, we will cut off the part we tried to turn down and make an adapter instead.

Motor arrived way sooner than expected. I am wondering if I am fitting the motor wrong. It looks to be sitting at an odd angle and the shaft extends down way too far to fit the worm.

Were you able to use the 12V heater cartridge that came with the Merlin hot end? If not, what did you use instead?

A couple questions. Did you guys have to cut down the stepper motor shaft to make room for the 4mm to 1.4mm worm gear adapter (the worm I got is a part number GW0.5-01-14 from gizmozone.com and matching 40 tooth worm gear GWG0.5-40-31) It would also be nice to get a recommendation for the spring. Also, I apparently ordered the wrong OD bearings . I am guessing the tiny ones I got would be fine, but doesn't seem worth reinventing the wheel. Thanks for introducing the great design. Really can't wait to get this up and running.

thanks

Just wondering why the UMO board runs off of 19V instead of 12 or 24V. Mainly wondering what limits the acceptable voltage for the board, so I can consider whether or not 24V could be made to work.

My UMO heater is basically impossible to take out without destroying it.

I had pretty good luck putting an RC filter on a normal fan. PWM is 30khz, which seems high enough to easily filter.

If it is not designed for PWM, could their be problems from the inductive load causing voltage spikes?

Is the hollow shaft slightly bigger diameter? I believe the standard for NEMA 8 is supposed to be 4 mm.

@foehnstrum. Would you mind trying to run your Nema 8 motor at 0.6A and see how that works? The slightly higher torque variety that you are using isn't readily available in the states. I think the difference in current limit largley accounts for the difference in torque, so testing at 0.6 amps instead of 0.8A ought to give some indication of whether or not the lesser motor will do.

After opening my CA glue, I keep it in a ziplock bag with as much air as possible squeezed out. This seems to keep it in good shape. The only issue was one instance where the cap wasn't sealed well enough and fumes from the CA caused severe degradation of the bag.

Minimum order is 3. Also not sure about the hollow shaft.

UM can take several days to respond. You just have to remain patient for a little bit. IIRC, updating your ticket moves your ticket to the back of the line, so don't do that until they respond.

12V or 24V version? Looking at getting an E3D v6 for a UMO and not sure which one to go for. I know the UMO supplies 19V to the hotend.

It helps that the UM2 board has digital current control and that the larger ground plane provides better cooling for the drivers.