Hobbed Bolt / Wade Extruder Issues

Hobbed Bolt on my printer does not have a uniform tooth pattern. Part of the bolt has normal indent arc that picks up filament correctly. Opposite side teeth are barely cut. If you hold it up to the light, the profile is an arc on one side and straight bolt shoulder on the other. Yet another QC issue. There is a thingiverse to hob your own bolt...will get one from eBay in the mean time. I thought were we 0ut of the woods on Hobbed Bolt issues. Guess not...

Wade Extruder Assembly Gear Slop If you look at the Robo 3D assembly videos, there is supposed to be an 8mm nut between the large extruder gear and the extruder bearing on the hobbed bolt. Purpose of the nut is to adjust the end play in hobbed bolt. The nut tightens against the nut holding the large gear. On my machine, the nut was replaced with a bearing between the gear and housing. (say what? ) This means the large gear is only held in place by the tension of the aircraft nut plastic lock ring, holding the large gear. Play adjustment in hobbed bolt is controlled by tightening the large gear with captive aircraft nut on to the hobbed bolt. Since the hex hole in the large gear is much larger than the aircraft nut, the gear is not not firmly attached to the hobbed bolt. The gear is free and has to rotate some distance during retracts, before the hobbed bolt starts turning. One fix is to nuke the bearing and replace it with an 8mm nut as in the conventional design. Admittedly this is a little tweaky to adjust since you have to get a wrench onto the the nut when tightening the gear/aircraft nut. Alternative is to keep the bearing, and embed the aircraft nut into the large gear with glue/epoxy/silicone/hotmelt to take up the slop. If you stay with the aircraft nut/bearing, maybe add some thread locker to make sure the gear does not slip on the hobbed bolt.

Robo 3D vintage shipped Oct 18.

 

which order number were you?

 

Do you have a photo of your assembly??

 

I have the same problem, my printer was shipped in November. I fixed the slop between the captive nut and the big plastic gear by wrapping the captive nut with one layer of blue painter's tape.

You can remove the gear by using pliers to keep the hobbed bolt still, and rotate the big plastic gear while the machine isn't powered up. The nut will fall out of the gear. Add the tape, then screw the gear with captive nut back together.That seemed to improve my prints a lot.

 

Yesterday I put some high-strength threadlocker on the walls of the gear nut retainer hole. I tried electrical tape but one layer would not fit. Be careful with the threadlocker because it can be very messy.

My son and I are just starting a long PLA print for a spool holder and so far it seems to help a lot. We used to get some periodic, missing plastic in areas with a lot of retraction. The missing sections were as long as a few cm. Now there are none so far through 7 layers.

When I get a chance I will mention this to be added to the FAQ in the FAQ thread.

BTW - I have a November ABS Robo with an ebay hobbed bolt and a grooved bearing. No problems with bed leveling, we just are very careful with the first layer thickness and double check the left/right Z height periodically.

-Steve