Hello,

I was this weekend finally able to test-drive my Orca v0.3. Camiel sent me the missing 'insert' last week.

Things are not working kind of like they should. The first extruder v9 tests without actually printing worked fine (i.e. clicking the 'extrude' button in pronterface).

However, when I started printing I encounter the following problem: after a few cm of filament, feeding the filament through the extruder becomes more and more difficult. This becomes worse and worse up to the point where the brass insert on the extruder stepper 'grinds' into the filament.

I've tried multiple temperature settings from 175 -> 240 to no avail.

To correct the situation, I need to remove the filament from the nozzle and cut the part that passed by the brass insert off (this is the part that went into the extruder). Then with a new piece of filament, the problem happens again after some 10 cm of filament. The brass insert is nicely aligned over the hot-end entry, so there is no 'S' bend in the filament as Camiel already described in another post.

Is there somebody that encountered a similar problem? If you did, how did you solve it? Possible causes that I think of and that I'd like to check with experienced printers:

• The heater block is not completely mounted against the extruder nozzle, there is a small gap of ~2mm. It was delivered that way, and I assume that it is not the idea that change this as the heater block was mounted firmly on the threaded piece with a nut. Could it be that the nozzle itself is not getting enough heat transferred? How does the v9 hotend of other printers look like, doe the heater block touch the nozzle screw?
• My hotend was delivered 07/10. There has been a notice on the blog that we needed to unscrew the PEEK parts and tighten the brass parts that screw into the central PEEK tube. Could it be that I have not tightened it enough or too much? Can this be verified?

Then two practical questions:

• Do you need to change the e-steps-per-mm if you use v9 and the mendel-parts Marlin firmware? Other things that need to be calibrated?
• Is there a way to slow down the extruder speed in pronterface/SFACT? I tried to reduce the number mentioned in the main GUI but this seems not to have any effect

My current setup:

• git master branch of pronterface
• sfact 42.4.1
• Latest Marlin firmware 0.9.3 from mendel-parts (new_opto_4G_acc)
• speed settings: 20 mm/s main feed rate, scaler 1.0
• no raft
• temperature: experimented with settings between 175 and 240 degrees C

Regards,
Hollie.

Hi Hollie,

Is there any filament coming out of the tip as you extrude. Nothing out of tip = blockage, some = some other problem.

On the pronterface screen, bottom left, is the extrude button / extrude speed. I have my extrude speed set to 5mm. I use a V6 hot end and it works fine at this speed for setup etc.

Not sure about the E_STEPS_MM for Orca/Marlin. I had to recalibrate mine as I have a Prusa. Notmatter which machine you have you should alway check/calibrate your steps specifically for your machine as there are always minor variations machine to machine.

If you can remove the hot end and test the calibration without it, you will remove one variable from the equation.

Well done for getting this far, it took me about 3 months to get the time to build my Prusa.

Geoff

Hi Geoff,

yes, there is filament coming out of the nozzle tip. I can print a few layers of an object. It is just that the filaments starts to jam after a short period when I'm printing.

I have in the mean time disassembled the hotend again. There are no signs of leakage, but I noticed this: when I insert filament that was used before (so that the filament has a small tip that is a bit wider than 1.75 mm because it has been in the 'melt chamber') then this tip smoothly goes through the metal parts, but it experiences some friction when it passes the PEEK separator. It seems that the hole in the PEEK part is slightly narrower than the hole in the metal parts.

This extra friction also happens when the hotend is completely disassembled, so I assume that it is not related to a possible overtightening of the metal parts in the PEEK part.

Is this slight difference in hole width intentional, or could this be the cause of the jams? -> the PEEK heats up, the filament in the PEEK also heats a bit, expands and jams.

I'm a bit reluctant to make the hole in the PEEK wider. I would assume that this is intentional. On the other hand I cannot find cross-sections of hotends that have different diameters in the filament route from input to melt chamber...

The pronterface GUI: re-checked it, and indeed, this works. I hadn't noticed because I only tried 5, 10 and 20. When I put it to 100 it is indeed faster.

Concerning the build time: Orca v0.3 assembles easily. Build time was <14 days spare time (and I don't have that much spare time ).

Hollie.

i´ve experienced the same thing and i think that the problem is that there is not enough heat in the melt chamber.

I was planning to cut little holes to the bottom M6 brass so that the heat gets easier to the tip, but i broke threads from the peek separator..

If that doesn´t help, i´ll try bottom brass part that has the nozzle in it.

http://www.reprap.org/wiki/File:Brass-barrel.png

Hi Jokeri,

I don't know for sure, because if that is the problem, then why does it not go away when I wait 5 minutes (heater on) and try to extrude again? By that time the filament in the melt chamber should have been molten again, no?

On the other hand, when I disassembled my hotend, I noticed that the threading in the heater block was not so ideal: http://imgur.com/6OQNO
As you can see, the brass threaded piece enters the heater block under an angle. Therefore it is not easy to tighten the nut completely flat to the heater block. This could be a reason why energy is not transferred in an optimal way to the nozzle.

Before changing anything there, I would like to get the confirmation that the PEEK part does/doesn't need to be more narrow than the holes in the brass tubes. I think that causes the jams in my extruder.

Hollie.

That is true..

Have you tried hand feeding the filament??

The peek part doesn't have to be smaller. Ive drilled the whole filament line to 3.5mm..

Yes, I tried hand feeding the filament. Same problem.

In the mean time I got in touch with James. He helped Camiel. He stated that the hotend is drilled after assembly. I had to tighten the lower brass tube further because it was not tightened enough. I also checked the hole in the lower brass tube. The hole is not in the centre of the tube. This means that by tightening it further as recommend by Camiel on his blog the hole in the PEEK is no longer in line with the hole in the brass tube.

I can imagine this causes the jams.

Time to get in touch with Camiel I think...

Hollie ... any progress?

We have three machines in this state, but I think it's software, or Skeinforge.

It goes through the motions of printing, but mostly the extruder never even tries to turn, even with no filament.

I have, by generating gcodes on RepSnapper, then saving them and loading them into Pronterface, got the base layer printed, but nothing after that.

If I don't get it cracked soon, I'm going to load all three machines in the back of the car, and drive them to Eindhoven, and haunt Camiel till they work!

James,

If all 3 machines are have the same problem it must be something common.

Do you have 'Dimension' activated in SF?

Perhaps I could send you a gcode file that prints on my m/c. It would not be that good on yours, but at least iof something comes out it would be a start. Email me at geoffd123 [at] gmail [dot] com.

Cheers
Geoff

Thanks, Geoff, I will e-mail,

and,

have you seen this:

http://www.mendel-parts.com/downloads/s ... e_big_zip/

Appeared in the early hours of this morning.

The instructions leave a LOT to be desired (just as well, or I'd be out of a job as an author!)

Am working on unravelling it all, and making sensible instructions (and seeing if it works!)

James