Z Problem can you help?

Hi Guys

just need some opinions on this Z problem

running at a slow 40mm/sec

have checked and also replaced hobbed bolt

have altered tension on filament bearing

have fan blowing across top of j-head

it happens at random layers

It is normally the same for the whole permiter and also the infill in the layer when it happens

happens with PLA @190C and ABS @230C

any ideas for me to try?

i have read that it may be a gap between the PTFE and the brass in the J-Head? will try this tommrow but not got spanner set atm to take j-head apart

Edited 1 time(s). Last edit at 09/17/2012 03:45PM by Enlightx.

I have the same problem and i'm stil looking what the problem is

Charlie

Maybe the hobbed bolt hasn't got a proper grip?
You can test this by turning of the stepper motors, and try to turn the big gear with your hands. (obviously with a hot hotend). You can feel if the bolt slips. If the slipping happens at a 'low' force, than the grip is not good enough. It's best if you can not make it slip (with a reasonable force).

Hi,
If it happens randomly and it effects the entire layer maybe it is Z axis slipping. If it slips randomly and your layer height is 0.2 you may get the odd layer at anything between 0 and 0.2.
Regards
Jan

I just corrected something similar on my Prusa. The X-ends I originally got were too loose, especially for the sprung z-axis nut. Printed off a new set and installed them. Also changed out my hobbed bolt (home made) to a manufactured one and the results have been pretty good.

J-head is probably not the problem. But if you're going to take it apart get some heat into it before you do. I broke my first J-head taking it apart when it was cold.

---

- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

just been working on the machine

put a dot on the extruder main cog and turned by hand

slips at same place everytime for a good 1/4 of a turn so looks like thats the problem

would also explain iv had this problem since i got a hyena hobbed bolt which was to replace a worn out hobbed bolt i got from ebay .

have this problem since fitting it

might have a go at making my own for a laff but int he mean time ill try getting the hyena bolt fitted again

just a pain to take it out as the m8 nut on 1 end just turns while trying to tighten up the other end

hi guys

just taken out the the hyena bolt out cleaned it all out put it back in and again its slipping in the same place

cleaned it out again and started very loose on the springs and tightned just a bit untill i got grip then as soon as it hit the mark on the cog slipped again

had a look at the bolt and its stripping the filament in 1 spot all the time then causing it to slip.

any ideas how i can sort it ?

could it be a problem with the bolt ? as iv had this problem since having it

How well aligned is the hyena?

---

- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

100% filament slips strait into the groove.

made sure when i removed the bolt to clean it i make sure it lines up 100% even have different thickness washesr to get it spot on

The only way I could see it being an issue with the bolt (other that an obvious defect like no teeth on one part) is if the hobbed groove was not concentric with the bolt itself.
You ought to be able to see that as it turns though.
Given it's always the same point in the revolution I'd be looking to see what is causing the filament to slip at that point. Something has to be increasing the drag for the gear to strip the filament.

I have a similar issue to the one you showed above but only with the cheap Chinese filament I have, in my case the issue is that the filament varies in thickness enough +/- 0.15mm ish that the extruder stepper misses on the wider parts, it's mostly my fault because I don't usually run springs on the cold end idler, so there is little to no forgiveness in the adjustment.

got another hyena bolt on its way as well as another bolt form ebay (needed a cheap backup anyway)

so we shall see


reallllly hoping its the bolt otherwise i have no idea

Weird. I'd get some heat into the hotend and open up the extruder use the large gear to feed the filament while keeping my thumb on the filament for pressure an to feel when the slip happens.

I just changed over from a hobbed bolt I made to a hyena and the difference is night and day.

---

- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

struggling with this problem guys not sure were to go from here now

got a replacement hyena bolt sent out and seems to be the same but now just stripping no slipping

if i remove the j-head and extrude i get 5mm filament moved perfect, i put j-head back in and get anythign from 1mm to 3mm

tested j-head heat and its spot on 1c out so its at the correct temp.

everytime i try i end up having to clean out the hyena bolt as it just strips badly and clogs everytime.

any ideas what else i can try ?

It can be that the jhead is not fermly tight enough. Try to turn it a litle bit more when it's on 230 degrees.

If there is a litle gap it can cause problems.

Charlie

ripped open the j-head look like the ptfe has had a problem was melted ptfe at the entrance to the j-head.

opened it all up and filament was not fitting loosly in the ptfe so replaced it.

tigned the head back on nice and tight

still stripping and then slipping i extrude 5mm in reality i get about 3-4mm now bolt is caked in abs again

if i run looser i only get about 1 - 2mm extruded

think they problem may be not enough heat for the ABS

looked on the spec sheet of the ABS im using (never used ABS before) and i thought it was 210 - 230c printable turns out its 210c - 250c

tested my esteps at 240C and works like a charm so started to do a print and seemes okay still get a bit here and there.

baby sat the print for a while trying to catch were it had problems and work out whats differenet

looks like my heat is dropping down to 235C at points and thats again causing it to skip as it cannot extrude easily.

im goign to try a print later at 250C as im guessin it will only drop to 245C at points then and be okay.

but is there anything i can do to help stop the drops in heat? i remeber theres some command i can run to tune the firmware? whats the procedure for this and how to impliment new settings?

You need better values for the PID temperature controller to avoid big drops in the temperature.

For details look here:
[blog.lincomatic.com]