Why is PEEK needed?

And thinking about it, because it is sold by the metre is must be illegal to deliberately under size it. It is 11% short on volume.

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[www.hydraraptor.blogspot.com]

Here (USA), I only see them being sold by weight (lbs or kg).

faberdasher Wrote:
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> It surprises me that the cheap PLA (from China)
> can be extruded at 150C. Assuming it's the same
> extrusion grade of Natureworks 4043D, the only
> explanation is that the material has been
> degraded, leading to shorter chain lengths with
> lower MPt.

I have no idea what Esunpla's PLA is made from.


All of you talking about extruding PLA over 200°C made me curious, So I tried it.

It works better ! It appears I was using a non-optimal temperature all that time. I have less occurences of filament cutting corners, the extruder needs less force, etc. I'm gonna stay at 210° C for now.

Thanks.

nophead Wrote:
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> And thinking about it, because it is sold by the
> metre is must be illegal to deliberately under
> size it. It is 11% short on volume.


I was trying to determine if they announce the volume for 3mm or 2.8mm on their product page :
"100 meters is about 880g or 638cc" for 3mm filament.

But I'm failing at the math. Shouldn't the volume be (cross section (which is Pi times r²)) times length ?

That gives me .3cm x .3cm x Pi x 100cm = 28,27 cc per meter, which means 2827 cc for 100 m.

That's doesn't seems related at all to the announced 638cc. Where am I failing ?

The area of a circle is pi R^2, not pi D^2.

So working back from 683cc gives 2.95mm. It would be great if it actually was 2.95mm or anywhere between 2.9 and 3.1 as that is what non-Bowden extruders are designed for.

Edited 1 time(s). Last edit at 12/08/2011 05:40AM by nophead.

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[www.hydraraptor.blogspot.com]

Back to topic: What about plaster instead of soapstone? you wouldn't need to machine it, even, since it can be cast in a mold. You could embed heat sink fins into the plaster to help with conductivity problems, and line the interior with ptfe to prevent porosity problems. It should also be relatively easy to print a mold ('course, you'd need a working printer first, or get a mold with your printed pieces). You also wouldn't need to tap , since it can be poured around the nozzle threads.

What type of plaster would be best? plaster of paris is easy and cheap to source, as is tile grout. Fire cement is a bit harder maybe, but would certainly stand up to the heat. Portland Cement? Dental Plaster?

I attached some quick mockups

taking it even further, maybe you can even skip the heater block entirely and encase the thermistor and resistor in plaster right around the nozzle. (not the orifice, though, of course.)

- Sorry Buback, please forgive this brief diversion...

@nophead - Chris, I understand your personal frustration... but the fact is most people would have serious problems if we supplied 3mm diameter filament. The typical expectation is that '3mm' filament will pass down a 3mm hole, so should be at most 2.9mm (as you noticed with all suppliers). Our internal spec' is actually 2.84 +/- 0.1mm (although we achieve up to 0.02 across some of our lines). However, '1.75' material will pass down a hole normally drilled to 2mm, so here our spec is 1.74 +/- 0.1mm (and better). These have become industry standards.

We spent quite some time considering how we communicate these dimensions. Our goal is to make 3d printing way more accessible, particularly for designers and crafts people. We felt that actually it would confuse newbies more, and everyone in the community already understands the nominal sizes... Our on site weight /cc estimates are all based on the actual (2.84/1.74) values. I want to be absolutely clear, we would never mislead anyone. I will be reviewing how and where we can add this info to save confusion. We want every customer to be delighted with their order. Chris- just drop us an email to arrange a refund. We are also happy about doing a custom 3.00mm extrusion run for you... just drop us an email (as we rarely check these forums). Cheers.

All the best,
Andrew

Edited 1 time(s). Last edit at 12/08/2011 08:33PM by faberdasher.

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Faberdashery

Sorry for helping the diversion Buback.

Regarding plaster : Aside from the heat resistance, I wonder how does that behave under compression ?

Couldn't the thread used to contain the nozzle break easily when the hotend push vertically into the build surface, even if the bed is on springs ? We all know this will happen sooner or later.

I'll give it a try. Such a thermal barrier would be a nice improvement to the reprap project, regarding costs, availability of materials, and ease of build.

This is a complete mess. It never used to be the expectation is that '3mm' filament will pass down a 3mm hole. Filament suppliers have silently changed the meaning of "3mm" filament but people selling extruder parts have not reduced the bore accordingly. Why would they as there has been no announcement of a change in the standard. and they probably won't because they are in the opposite situation as people will complain when the have the old style "3mm" and it jams.

The problem is 2.74mm ABS filament does not work in a barrel designed to take up to 3.1mm (i.e. bore 3.2mm or 1/8") and the maximum flow rate achievable goes down as the gap between the filament and the barrel gets bigger, so I find 2.85mm ABS unreliable at the flow rates I have been using for two years. PLA might be a bit more forgiving but the change my ABS supplier made has cost me hundreds of pounds in lost production.

I think all suppliers of filament should give their upper and lower bounds and suppliers of nozzles should give the exact internal bore size.

Starting from scratch, standardising the bore make sense, but 3mm was an existing standard for welding rod. Also where is the consistency if "3mm" filament is intended for a 3mm bore and is centred on 2.84mm and "1.75mm" filament is intended for a 2mm bore and is centred on 1.74mm?

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[www.hydraraptor.blogspot.com]

Hello guys. I am new in this forum. I can see that are people with a lot of mechanical experience. I got an idea. What about making a hight temperature nozzle from an used old benzine engine spark plug. It is cheep, sustain very hight temperatures,
mechanical stress, vibrations etc. It may hold easily 550 C for a very long time.It has a cooper or a metal inner rod which can be drilled to make a nozzle. It is somebody wiling to try and post the results?
Best regards,
Octavian

A long time ago I tried to use a car spark plug but the ceramic was too thermally conductive.

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[www.hydraraptor.blogspot.com]

@nophead:

We have been testing abs from New Image Plastic here in the U.S. We got 30 pounds from them on single spool. In the process of spooling it on to smaller spools I ran the filament through a laser mic. Diameter went from a low of 2.97 to a high of 3.01. The only downside for us is that it appears to need extruder temp of around 245-250C. We run 22 printers all with budaschnozzles which don't do too well at those temps. On the plus side the price is way better than anywhere else.

I print with NIP ABS exclusively with the nozzle at 230C. I used a Budaschnozzle 1.0 earlier and now J-heads.

@brnrd

If you don't mind me asking, what type of settings are you using as far as extrusion speed and retract speed? I revisited using this plastic last night but again was having issues of the filament slipping and causing air prints. I can get it to run on my development machine with a J Head @ 245 C but on all of our production units I can't consistently get it to print at 230 C. Any insite you could give would be greatly appreciated.

Are you sure that you set the firmware to the correct thermistor? I think the Honeywell thermistor is 7 in Marlin and Sprinter.

Yeah they are setup correctly, I even double check actual temps with Thermocouple once a month. I am just wondering if I'm retracting too fast as it seems to always fail after a retract. It then slips and starts air printing. Sometimes it will get an hour into a print and do it, other times it happens fairly quickly. Hate to let almost 30lbs go to waste. Thanks again.

I'm using the default retract settings in slic3r: retract length 1mm, speed 30 mm/s, extra on restart 0 mm. I'm using a gearless NEMA17 extruder with a 0.35 mm J-Head Mk-V but I don't push the speed too hard (perimeter 30 mm/s and solid infill 80 mm/s) even though I've determined that it can extrude at 150 mm/min of 3 mm ABS. That should allow me to print up to around 180 mm/s feed rate.

I've also checked the melt zone temperature with a thermocouple and it's easily within 5C.

How fast are you printing?

brnrd,

Lowered the retract setting to 1.25mm and slowed the retract speed down and voila 13 prints off 9 different machines without a hitch. All at 230 C. I can't thank you enough for your help. Now just need to order 200 lbs. Thanks again and sorry to hijack this thread.

BTW, your extruder is a nice clean design! Going to print up one and put it on my developement machine.

I've updated the design but I haven't finished it up for release yet.