Ordbot recommissioned

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Ordbot recommissioned

Postby WillAdams » Sun Mar 01, 2015 7:45 pm

Received an Ordbot from Edward Ford (Thanks!)

Swapped in some minor replacement hardware just 'cause I'm fussy, and connected it to an Azteeg X5 mini (I'll post the config file presently) and even w/o any especial effort, it's printing better than my "repstrapoko".

The only real issue was one of the Z-axis motors seeming to not work --- turned out to be mechanical, even though things seemed level to the eye, and the threaded rod seemed to turn easily enough by hand, the motor wasn't able to budge it --- found that out whenI resorted to swapping a motor in. Once I loosened the Z-axis nuts, lined things up properly and tightened things back up, it all ran fine.

Next up is sorting out the wiring, leveling the machine (never mind --- figured that out), working up some way to attach the power supply and reworking the enclosure that I printed up so that it can be attached and the wiring properly run through it and getting it attached.

Then I'll have to see about adding an LCD / control panel....

Really appreciate the nice, open design and all the build logs which have been posted thus far.

Thanks!
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Re: Ordbot recommissioned

Postby WillAdams » Tue Mar 24, 2015 1:48 am

Well, that was a quick three weeks.

Machine worked fine until yesterday, when a print (from a file I've been printing successfully many times previously) came out blobby and very smooth.

Tried again tonight w/ much the same result and noticed the extruder was running hotter than usual. Switched filament and tried a different file until the hot end began falling apart. Questions:

Does a J-head require active/ direct cooling from a fan?
Does an Azteeg X5 mini need a fan?
Does hot end auto tuning need to be re-done periodically? If so, how often?
Should I try an all-metal hot end? How is the B3 Pico?
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Re: Ordbot recommissioned

Postby Zebethyal » Tue Mar 24, 2015 3:33 pm

The subject of cooling the J head can be quite a hot topic ;)

to a degree it depends on the J head in question and how it has been put together, what size filament it was designed for and what size filament it is using.

My first Chinese J head was designed for 3mm filament and I was using it with 1.75mm - I simply replaced the PTFE sleeve. This one worked fine for a few months, then I had issues with it clogging (dust) and so took it apart and cleaned the aluminium part with a blowtorch.

Again it worked fine for a while, however each time it clogged and was cleaned, it did not go back together quite as well afterwards, I cleaned the threads on the Peek, and used PTFE tape on the threads, but it started leaking from the join and started dripping on the prints.

I replaced it with another Chinese one, this time one designed for 1.75mm filament after I was a bit to enthusiastic with the blowtorch and melted the threaded part on the first one :)

This one started having issues very quickly - the filament was melting too far up the Peek section and would ultimately prevent the extruder from pushing the plastic through.

I solved the problem by drilling out the threaded part of the aluminium section to 4mm and then pushing a length of PTFE into this 4mm hole, and running it all the way through the Peek section and all the way up to just below the hobbed bolt of the extruder.

As a result of this, the Peek section no longer gets hot and if I try and cool the piece being printed, it now cools the hot end too much! this with a fan that I can barely feel the air movement from.

I have had no issues with my J head since this drilling exercise.

Hope this helps
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Re: Ordbot recommissioned

Postby cvoinescu » Tue Mar 24, 2015 9:38 pm

The only J-Head is the one made by Reifsnyder. The Chinese ones are clones, and bad ones at that. Your adventures illustrate the typical results of using a rip-off.
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Re: Ordbot recommissioned

Postby Zebethyal » Thu Mar 26, 2015 12:30 pm

There are many clones/copies, not just Chinese ones, the product itself is open hardware under the GPL license, so free for anyone to reproduce, copy or modify, and therefore not a 'rip-off' if someone other than the original inventor makes it, however good/bad a job they may perform on that copy.

This whole 3D printing hobby is about copying, improving and making it cheaper/more accessible, economies of scale are always going to kick in at some point, having only one supplier of an item is a monopoly and the same as closed source.

I can dispose of half a dozen Chinese J Heads before I am close to the cost of a "genuine" one, which may very well last 2-3 times as long as a copy.

As far as I can tell all hot ends are prone to clogging due to dust, etc, yes you can try and avoid this with a piece of cloth, better filament, etc, but ultimately they all clog at some point. The more you clean, the looser the fit on re-assembly, it is plastic against metal after all and won't last forever. Cleaning the threads on the PEEK usually requires re-tapping which again makes it loose.

Most of the issues I have experienced have also happened to just as many people who have "genuine" hot ends of various types, all you need to do to prove this is look around the web for the types of issue mentioned.

Why do you think the "genuine" J Head is forever being 'improved', it is currently on Mk 7-E and MK 8 from a development viewpoint as can be seen here, this implies they still have not yet reached perfection and it still has room for improvement.

I was merely offering advice based on my experiences which the OP can choose to take on board or ignore as they see fit, I am not seeing any additional helpful advice from yourself in this regard.
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Re: Ordbot recommissioned

Postby cvoinescu » Sun Mar 29, 2015 2:14 am

There's a difference between using the design (okay) and using the name (not okay without permission) or pretending your product is the original when it isn't (not okay at all).

Several people have examined clone J-Heads and compared them to the original, and posted their findings. I think all of them agree that most copies are not built to Reifsnyder's (open-source) specs. The worst problems are melt chambers not drilled deeply enough (so that the narrow orifice is way too long), and problems with the PTFE liners (often there's no means to retain them, meaning that molten plastic can push them out). There are some good clones too, and Reifsnyder himself points that out.

As for the J-Head development, I did not say anything. It was pretty much perfected at Mk V-B. The following versions were due to the original thermistor no longer being available (Mk V-BV), switching from a resistor to a ceramic heater element (Mk VI-B), an easier to machine PEEK holder (Mk 7-B), a different material for the holder to increase the working temperature (Mk 7-E), and an experimental design that's not released yet (Mk 8). You'll notice that up to the new experimental design, the geometry of the nozzle and melt chamber is the same; the only changes are the second thermistor hole and the different heater element hole size -- not changes indicative of a continuous search for a working hot end, but the kind you'd expect in a proven, mature design.

I've had no problems at all with clogging in my J-Head. It just worked from day one and kept working with no maintenance whatsoever (let alone modifications). It even resumed working perfectly after being stored in a box in the garage for six months, with a piece of PLA in it. This is a very different experience from what you're describing, so I am further reassured that my J-Head was well worth the money. This was the point I was making, and I still believe it's helpful.
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Re: Ordbot recommissioned

Postby WillAdams » Sun Mar 29, 2015 9:10 pm

All of that makes me even sadder that I destroyed my J-head.

I've gone ahead and ordered a Pico from B3 Innovations. Hopefully third time's the charm.
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Re: Ordbot recommissioned

Postby WillAdams » Thu Apr 02, 2015 12:57 am

Well, I've got it, and it's installed, but I'm stymied by Marlin Table No. 1

Can't puzzle out which thermistor that is to Smoothieware.
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Re: Ordbot recommissioned

Postby Zebethyal » Thu Apr 02, 2015 9:25 am

@cvoinescu
With regards your J-Head never having clogged - good for you, you probably buy better quality filament than me (mine tends to cost around £12.00 per kg), have less dust around, take better precautions against dust, use your printer less than me (maybe/maybe not), etc, etc.

Storing the J head with a PLA plug and in a box will have prevented any unwanted particles entering.

Clogging due to unwanted particles has nothing to do with the make or build quality of the hot end, if the particle is too large to push through the 0.2/0.3/0.4/0.5/whatever mm exit hole, it will clog. The smaller the hole, the greater the probability of a particle being too large.

@WillAdams
Why not simply fit the thermistor you had in the previous J-Head? you know the table for that worked and you know what make/model of thermistor it was.

Failing that, buy some additional thermistors of a known type and swap out the one in the new hot end.

I bought 10 ATC Semitec 104GT-2 thermistors from China for $4.99, previously I bought just a couple from Rapid Online for £1.02 each, I use one on my heated bed as well, so I only need to worry about a single known thermistor table.

Yes, I have used a couple of different Chinese J-Heads, but I use my own 104GT-2 thermistor because the one supplied with each of the J-Heads was a complete unknown, I would do the same for any other Hot end, whatever make, genuine or otherwise.

For the sake of not having to perform any rewiring and guessing at the make/model of thermistor, I simply remove the Kaptan tape, use my original thermistor and heating element and tape it back up again.
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Re: Ordbot recommissioned

Postby WillAdams » Thu Apr 02, 2015 6:00 pm

I'm not convinced I had the thermistor table right, or that it hadn't been damaged by the initial misadventure. I'll see about testing it later.

So, I've got the new Pico Hot End installed, and I now know that Marlin Table No. 1 == EPCOS100K, so will begin a cautious calibration. Already canceled 1 print 'cause it was over-extruding and the head was getting dragged across solidified ridges of filament.
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