Grinding noises when extruding

1TxMarvel

I have an A3S that I’ve been using since Christmas 2018. This past month or so I have been hearing some noises during X&Y moves. Nothing real bad, sounded just like I needed to do some routine maintenance. Then my extruder motor started making loud clicking/grinding noise that sounded like the filament was jammed. That is when I decided to take it completely apart to inspect everything, check belts, lubricate rods, etc. Everything looked great. I can move move X and Y freely with no resistance or noise. The belt tension felt good and there was no debris interfering with travel. I disassembled the extruder assembly completely to the point I even removed the filament detection switch. Pulled bowden tube and all. I checked the gear on the extruder stepper motor, made sure the filament release spring was seated, everything I could think of. 

I put everything back together, fired it up and...Same Problem!!! I walked away yesterday so nobody got hurt. 
This evening I tried again.  I even get the clicking/grinding when I am auto loading the filament so it is not a hot-end jam. 

I am at my wits end.  The extruder is by far the loudest but the other axis just don’t sound right either. 

Is it possible it could be a voltage problem from the stepper drivers?

A couple of clarifications. 

1. I am using the original stepper drivers it came with.
2. I am using the original firmware. 

3. I am an electronic technician (35 years) so I am comfortable with any test procedures if someone can give me some guidance. 

HELP PLEASE!!!

Stephen Todd

Are you using the original power brick, or did you upgrade to a more powerful PSU?

1TxMarvel

Original power brick. 15 amp

Stephen Todd

15 amps is plenty of power - my V1 A3s came with a weedy power brick that burnt out in 3 days as it was under powered, so I upgraded to 15 amps

I'd check the voltages on the stepper drivers and adjust if necessary:

• X = 0.4 - 0.55V
• Y = 0.4 - 0.6V
• Z = 0.7 - 0.85V
• E = 0.55 - 0.6V
  
  https://jgaurorawiki.com/a5/stepper-drivers
  
  

Samuel Pinches

Welcome @1TxMarvel !

Oh boy, I know how frustrating that can be....

Lets tackle one axis at a time....

For extruder grinding, that usually means there is some significant resistance. With the hotend hot, can you extrude filament manually by hand? i.e. - if you press the extruder clutch button to release the motor, and then try to feed filament with your other hand? Is it easy to do, or do you feel heavy resistance?

If so, then lets inspect the hot end - unscrew the bowden connector on the hotend side, and retry to manually feed filament, and examine if there is still significant resistance when extruding by hand.

If so, may be worth replacing the small section of bowden tube that lives in the hot end, or tearing that down further. It may be worth ordering a spare hot end assembly or spare thermistor, as they are fairly fragile parts. Be careful not to twist the hot end and put stress on the heat-break, since the heat-break is only a very thin metal tube and will snap/tear, requiring you to also buy an x-carriage j-head. When cutting bowden tube, do not use scissors as you will crush and deform the tube. You must use a razor blade or other sharp edge to slice it. There is a 3D printable guide to help you cut a new section to the correct length here. I've attached the STL to this post also.

You could try tuning the stepper drivers, turning up the motor current slightly. Please have a read and then feel free to ask questions here.

Best,

Sam

Samuel Pinches

Looks like @Stephen Todd beat me to it

1TxMarvel

Thank you all. I can manually extrude pushing clutch and push filament through hot end and out nozzle. What is odd is I get that noise even when I’m doing the auto filament load even right in the beginning when the tube is empty. I have a printer profile that has some fairly aggressive retraction and that is when you can always hear it clearly. 

Stephen Todd

As you hear it when loading filament, I'd try tuning the extruder motor stepper driver, but I'm now thinking that its something mechanical

I'd suspect something is worn out - either the whole filament drive mechanism, or the drive motor

Does it make the noise with no filament in the bowden tube? - i.e. pretend printing

1TxMarvel

I will try that. I can have it make a little noise when I do a fast 10mm extrude retract manually from keypad without without filament. Let me verify that mist to ne sure

1TxMarvel

Bad typing. On another note, if I do need to get a new drive assembly would it be worth installing a direct drive as opposed to bowden style? I ask because I’m not sure the A3S would have enough X Axis available. 

1TxMarvel

Ok, i just tried. These are using “fast”as opposed to ”normal”  With the filament removed i have no noise when inserting or retracting. If I have filament in the drive I get the noise inserting but not retracting. What is odd is if I put tension on the filament when inserting it does not make the noise. I also put pressure when retracting and am getting no noise. 

I don’t know if a quick video may help. Thank you again for your assistance. 

Stephen Todd

If you have adjusted the stepper voltages to the upper limit, then its physical resistance inside the bowden tube, or insufficient pressure on the feeding gear (weak spring, cracked/deformed pressure lever)

I'd put a washer underneath the spring, or stretch the spring in order to increase pressure against the filament

I'd also consider pulling out the bowden tube from the black pipe, shorten it at both ends (could be worn), and let it float free between the extruder motor and the cold end with minimum possible length

You could fit a new feed gear - maybe a better type (slightly larger, sharper teeth, more/less teeth)

Some people oil the filament with some sort of natural oil - canola, peanut, etc. - you could print out a filament cleaner/lubricator and fit it before the feed mechanism - I run mine dry, but you can oil the sponge

https://www.thingiverse.com/search?q=filament+lubricator&type=things&sort=relevant

Laser8302

Don't forget to cut the "blob" of filament off the end. That could be causing extra resistance in the bowden tube.

I personally ditched the stock extruder and went to a BMG type withe 3:1 gearing.

One last thing to check is your acceleration and max feedrate of your extruder. Try a stupid low acceleration like 300mm/s/s and max feedrate of 70mm/s to start.

1TxMarvel

Thanks Stephen and Laser. Last night I narrowed it down to the extruder. The spring was getting weak. I always use the release to fill or remove the filament. (Impatient). I stretched it some but they have memory wouldn’t stay. That is a great idea about the washer!  I want to get a new extruder but couldn’t find a Xref except some for Ender3. Could you send me a link for a good extruder.  I’m also going to upgrade the stepper drivers and load the community firmware. I’ve been using this stock out of the box for 1-1/2 years with zero problems. Great little machine. 

Once again, I want to thank everyone for all of your help!

Stephen Todd

You could stretch the spring, then heat with a blowtorch till glowing, then quench in oil - that will set it - but I know that it is a standard spring, as somebody said they found a replacement easily

I've not replaced my standard extruder yet, but think people have fitted readily available extruders - on here somewhere

1TxMarvel

I like the washer idea.
Although it would be fun I’d probably mess it up if I did the blow torch.

Stephen Todd

I mess with air rifles, and spring cutting, coil collapsing, grinding, polishing, pre-tensioning with packing washers for power adjustment is all part of the fun - but its easier with bigger springs

For small springs, you could make your own
https://www.youtube.com/results?search_query=make+spring+with+spring+wires

1TxMarvel

I need to try that.  I remember when I was a kid my dad made some springs like that. I thought that was so cool at the time