How to Cut maintenance time with new extruder and better levelling

I am finally having success with my Prusa/Mendel printer thanks in no small part to the generous support and advice by members of this forum and my kit’s vendor (MixShop).

Now I am back for more advice concerning extruders and leveling so I can cut my maintenance time to less than my printing time...

My “Wade’s geared extruder” works well but tends to jam from time to time and requires too much down time to strip, clean and reassemble the extruder and head, in fact I have spent more time stripping and reassembling than printing. I have two problems I can identify, 1st the cleanup time and second the loss of filament flow to the nozzle which I attribute to the amount of pressure from the bearing against the filament and the hobbed bolt. I have had some cleanouts showing plastic doubled up after the hobbed bolt. Some plastic residue in the hobbed portion, sometimes no plastic indicating variation on spring tension setting.

These problems are extruder related. I have seen version of extruder that are easy to clean and have visual sight of the bearing/hobbed bolt/filament interface and a simpler hinged assembly.
Question 1: What is a less problem prone extruder that hopefully will allow recycling of the “Wades” components (excluding Plastics which are beginning to split apart).

My prints often have stopped because the nozzle will drag on the bed despite being levelled before the print started. There must be vibration of the nuts and bolts losing the ”level”. I am able to level fairly easily, but an easier/faster/foolproof way for the bed itself, would be a blessing as would a way to stop the continual loss of level. I have use loc-tite, and jam nuts, but still requiring leveling too often, in fact before each print.
Question 2 : What suggestions/methods are available for stabilizing my bed so it doesn’t go out of level so often?

Thanks in advance.

Bob

1. i use [www.thingiverse.com] works great, easy to access.

2. how are you leveling at the moment? Can you post a pic of your bed?

what size filament are you using?
what is the quality of the hobbed bolt like?

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Usually, once the bed is leveled well once, you need to print an Z-calibration helper and just adjust the Z-height at the point of the endstop instead of re-leveling the whole bed each time.

I have now gone to the variable Z-endstop option and it saves me SO much time. Be sure to have a good measuring paper with you. The thickness of paper can vary a great deal and also influence the way you measure the Z-distance to the printbed. I usually calibrate it too tight...

Be sure you are not printing too hot or too cold, also, I myself keep on extruding filament when it's heating up, hitting the 'extrude' command withint Repetier Host every once in a while when it's not yet up to temperature, but already hot enough to carefully extrude some.

Blockage can come from a bad copy of the hotend, or bad quality of filament. And a whole great deal of other aspects.

Attached are photos of my bed and hobbed bolt.

I have my printer sitting on a piece of MDF with a 3 point leveling system. This part is easy to level.

The heated bed is supported by 4 bolt/spring/jam nuts. Perhaps a 3 point leveling on the bed too would simplify levelling?

My hobbed bolt is commercial and of good quality and workmanship. I have a 2nd as a spare and it is identical to the 1st one with uniform measurements.

Bob

I believe bed leveling is measured from the nozzle tip to the print surface.

A bubble level is not going to help with the gap at the nozzle.

I use a piece of office paper to set the gap (.1mm or .004").
I do this directly at the leveling screws.

BE WARNED

The idler bearing can 'bottom out' and stop spinning on the Wades Gear Extruder, when the hinged part is moved forward.

I had to file down a fair amount of material indicated by the end of my file in the picture attached.

The bearing would turn freely, but as soon as I put the idler in place close to the hobbed bolt, it wouldn't turn anymore.

Shadowram,

Are you suggesting that I set my bed by setting to "paper" clearance at the 4 corners of the bed to the homing height of "Z"? I can see this as being as easy and likely more precise than using a level, either bubbble or electronic.

What about 3 measurement points instead of four ie. 2 corners and center of opposite side?

Bob

Using a paper sheet certainly is more accurate than a level - it must be done like this.

What hotend are you using? I found that what I thought was an extruder problem was a hotend problem. New hot end, no problems. If your hotend doesn't work just right, to much pressure builds up or the hot end clogs.

BobHewson Wrote:
-------------------------------------------------------
> Shadowram,
>
> Are you suggesting that I set my bed by setting to
> "paper" clearance at the 4 corners of the bed to
> the homing height of "Z"? I can see this as being
> as easy and likely more precise than using a
> level, either bubbble or electronic.
>
> What about 3 measurement points instead of four
> ie. 2 corners and center of opposite side?
>
> Bob


My suggestion was about the Wades Extruder possibility of jamming.

But yes for Z calibration, I would do all 4 corners AND the center.
There's a possibility that your bed could be concave or convex.

A bubble or even an accelerometer (electronic level) will never be accurate enough.

Keep in mind, even if you did make the bed perfectly flat to gravity, there's nothing saying the rest of your carriage is level as well.

What matters is the carriage is level to the bed. (Gravity ignored).

So yes, use the paper clearance method at multiple points.

Jzatoopa,

I have do not know what the designation is for my hotend. It is the "standard" hot end sold with Wades extruder. If you check MixShop site in Toronto, Canada they show the components used. When I purchased I bought the Prusa/Mendel kit which included all the bits and pieces.

Bob

Does your hotend look like this one?

[www.mixshop.com]

I'm not seeing any others on their site.

jzatopa Wrote:
-------------------------------------------------------
> What hotend are you using? I found that what I
> thought was an extruder problem was a hotend
> problem. New hot end, no problems. If your
> hotend doesn't work just right, to much pressure
> builds up or the hot end clogs.


Care to expand on this? Which hot end were you using, what was your issue, and what did you switch to?

I often encounter these problems too. I don't really have any idea why it happens but sometimes it can be very irritating especially when I have lots of work to do. Thanks for the information. I'll try to see what I can do with my printer basing on the information you guys shared.

Jatopa,

No, that is MixShop's new extruder for their new machine. MIne is the one shown in attached photo.

Attached a photo of my extruder hot end. It consists of a PTFE rod 16cm with a hole through for the filament. One end is drilled and tapped to 5mm to take a 6mm threaded brass rod with a hole through it. There is also a copper collar for both rigidity and as a heat sink for the PTFE tube. This assembely screws through the heater block (aluminum with
2x 5 watt resisters and a thermistor. The threaded portion protrudes out of the heater block and has the 0.35 nozzle fastened to it.

I have certainly had issues with my hot end. have probably stripped it and reamed all holes 20 times. I at one time figured a problem was feeding the filament (1.75 PLA) through the extruder body into the PTFE was a fretty tight fussy job so made a tiny relief of the PTFE hole (like a funnel) figuring it would help guide the filament in. No, didn't work, just made jamming worse and the filament would double over itself and cause a blockage. One more reason to go to the hinged Greg/Wade extruder.

In any event I am rebuilding my hot end with new PTFE and Brass rod so that should not be an issue.

Bob

Edited 1 time(s). Last edit at 05/08/2013 11:01AM by BobHewson.