Delay in my extruder feed???

I figure I can’t be the only person with this issue.

Whenever my print head has to pickup to move to another location when it restarts there is always a delay from when the feed gears start moving to when the melted filament start to come out resulting in a portion of a layer missing anywhere from a few mm to 8mm. Also sometimes there is a slipping/grinding sound which has the same result. It can’t be the belts because the head stays on track with the print so I’m guessing it has to do with the extruder or its timing. Ive looked at the gears but cant see a way to tighten or adjust?

If I can fix this it will help my print quality greatly it also makes some of my prints fail


Thanks

 

oh i'm using MatterCantroll

 

Have you checked/cleaned your hobbed bolt? What temp are you printing at, maybe try hotter. Turn your retraction speed down to 1200 or even 700 and your retraction distance to 1 or 2mm. Also try packing your filament guide springs with more washers so there's more tension. I've done a lot of tweaking to try reduce the number of retractions that occur to reduce the chance for filament grinding but it can then become a battle with blobbing and stringing, it's a difficult balance. You may also need to tell it to extrude extra filament after retraction but I doubt it. I greatly prefer Repetier + Slic3r to Matter Control but am currently trying to get Simplify3D to produce prints as good as I got with Slic3r.

 

Also make sure your spool turns freely so the extruder doesn't have to work to pull the filament. Definitely print/build a spool holder that uses bearings. I just finished setting up mine and wow does it turn freely, I haven't had a chance to print with it yet though and can't wait to watch it in action.

 

I’ve printed a new spool holder and it works great. I’ve also heard a lot about the hobbed bolt but I’m not sure what/where it is? As for the temp if anything I’m running hot (I think) 205c-210c, I was actually thinking about dialing it back abit. As for the settings, that sounds like it could take care of at least some of it. I check to see if I can find those settings in MatterControl as soon as I get a chance. Do you know if MC has them?

 

The hobbed bolt is what feeds your filament. If you take out the 2 screws with the springs on the filament guide and open the filament guide you'll see a bolt with teeth/hob. To clean it you should need to take it out, just heat your extruder to say 175 and pull the filament out so then you can access the hob with a stiff brush, I use an electric shaver cleaning brush, to clean out any/all plastic clogging the hob.
That temp might be a little high for the stock hotend. I'm using 210-215 with the Hexagon hotend for PLA but I need to experiment with a lower temp now that I've tweaked other things I use to run 196 with the stock hotend for PLA. Be aware that different brands, colours, and even batches of filament will likely require temperature tweaks, always start with some calibration test prints when you use a brand new roll of filament, it's better to bin a couple small test prints than a big yoda head.

 

Oh sorry. I tried MC briefly and really didn't like it and that was that so unfortunately I can't help you with MC settings. There's a thread for MC I think which may help.

 

What software are you using that has all those control settings?

 

Two possibilities - The hobbed bolt as mentioned above and/or the hobbed bolt is slipping back and forth in the big gear.

The hobbed bolt needs to be replaced with a good one especially if you see any plastic shavings on it. There should never be any plastic shavings on the bolt. The measurement is 15mm from the bolt head base to the hobb. In addition to the new bolt you can also add extra washers to increase the spring tension, or use stronger springs. Hopefully Robo3D is working on replacing those bad hobbed bolts.

The bolt head can slip during each retract/extrude cycle causing a delay in both retract and extrude. To check this turn the gear back and forth and see if the bolt head slips each time. To fix this put a drop of extra strength Locktite (red) between each flat of the bolt and the gear. Be careful not to put too much or to get is on the threads. Wait 24 hours for it to dry. The Locktite can be scraped off the bolt when you need to remove it.

 

Oh yeah, I forgot about that SteveC. I made some shims from a coke can, works great. They're held in firm with an extra nut, I do have an after market hobbed bolt which is a little longer though.

 

One think I really like about this forum is seeing the wildly different ways that everyone comes up with to solve the same problem. And there are certainly a lot of problems to solve.