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Author Topic: Printing with PLA  (Read 722 times)

webby2

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Printing with PLA
« on: November 28, 2018, 08:48:13 am »
I have made some mods to my printer,, nothing big there.

What I just noticed is interesting to those whom use PLA.
What I have been using as a glue is DAP Rapid Fuse all purpose adhesive.  It works fairly well for general gluing of parts but I just used some isopropyl alcohol to clean up the excess glue around a bearing,, I was not so happy with the fit of the bearing as far as alignment goes,, I tried to tweak it a little bit and nothing really moved but about 1 minute after I cleaned up the excess I tried again but this time the plastic and glue all acted kind of like a liquid and allowed me to reposition the bearing alignment so that it is much better.

webby2

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Re: Printing with PLA
« Reply #1 on: November 30, 2018, 11:46:07 am »
I found that if I have a hole for a shaft that is not right,, it might be a little out of alignment or a little small or what not,, if I place the shaft through the hole and then spin it with my drill press,, or whatever will do the job,, I can use the friction to slightly heat up the PLA and allow it to form into a better position\shape.  This seems to work for small errors.

I also use a razor blade and "back scrape" the PLA to clean up the part, by back scrape I mean having an angle on the blade and sliding the face of the blade across the area to be cleaned up.  I find that this also seems to create a sort of surface friction melt thing.  I use the edge of the blade, whether that is the sharp edge or the square edge, not all edges work.

webby2

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Re: Printing with PLA
« Reply #2 on: June 03, 2019, 04:55:26 am »
An interesting thing to remember.

PLA will wear out metal parts.

I have printed a lot of parts on my printer, changed the print head\extruder out to a Bowden style system,, but other than that change I have been running with the same parts, so that is only 1 new hot-end and 1 new nozzle.  I modified my extruder to accept the Bowden setup so I have been using the same hob all along.

So the other day I used the NEW Basic Premium filament from Amazon and my printer would not work with it, I had an older partial spool and put it back on and it worked fine, back to tha Amazon premium and no good,,

I started replacing some of the parts I was planning on but in a less planned out method than what I wanted, I was looking for the reason my printer did not like the new filament.  I now have a new hot-end and cooling fan for the hot-end, not to be confused with the parts cooling fan, a new sheath that goes between the extruder and the hot-end, a new nozzle, a new heat element and a new thermistor,,  all this and still no joy.

Now you can see why I mentioned the hob,, yep that was the problem mostly.  The new filament is about 0.178 to 0.174 and the older stuff was 0.175 to 0.173,, the slightly larger diameter filament makes for a slightly higher friction in the sheath, and a slightly higher pressure making it slightly harder to push the filament through the nozzle and my hob was worn really bad,, smooth in a few spots even.

webby2

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Re: Printing with PLA
« Reply #3 on: June 23, 2019, 07:38:47 am »
I am using a press fit drive piece to connect a motor to one of my testbeds, it is a 2.3mm diameter shaft motor so it is very small.

When the drive motor is loaded and starts to heat up the output shaft starts to "slip"  inside the connection piece and has a few times now actually allowed the connection piece to get hot enough to warp and bend.  On larger diameter shafts I have not had this issue so much, or if I key the connection.  I have also tried super-glue with some success but as I am using it right now it is not a good way to go.

webby2

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Re: Printing with PLA
« Reply #4 on: June 29, 2019, 12:53:27 pm »
An interesting printer issue.
My sheath that connects the extruder to the hot end came loose, that is the fitting that holds the end of the sheath to the extruder wore out.

Did not think that would happen but it would explain some print errors I have had,,,,

webby2

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Re: Printing with PLA
« Reply #5 on: July 24, 2019, 10:38:45 pm »
I bought a new printer
https://www.amazon.com/TRONXY-Semi-Assembled-Filament-Adjustable-Eccentric/dp/B079LYSQCP/ref=asc_df_B079LYSQCP/?tag=hyprod-20&linkCode=df0&hvadid=241942224913&hvpos=1o1&hvnetw=g&hvrand=3997737725117473230&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9033255&hvtargid=pla-707605623047&psc=1
but mine does not have the filament detector.

This was really easy to assemble and does a fairly good job.
HOWEVER
I found out the hard way that you need to adjust the Z stop when the bed is hot.
The paper drag setting also needs to be so that you just start to feel a little roughness when pulling\pushing the paper under the nozzle.  I am assuming that the printer firmware has a Z gap built into it,, I have not looked at the firmware settings that it is shipped with.
If you set the Z stop to close to the bed not only do you get a really bad elephant foot thing but it will fuse the filament to the magnetic build sheet, thus leaving huge holes in the build sheet.

I am using Kiss slicer software and Pronterface to print directly from my computer, the small card that comes with the printer can also be used if you do not want to have your computer doing the printing server thing.

My other printer, which is a modified RepRap Guru Prusa i3, I am using a Raspberry PI as the print server running with Repetier-server free print server.

webby2

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Re: Printing with PLA
« Reply #6 on: July 25, 2019, 06:38:07 am »
one thing to mention with these printers about hole size,,

It would be suggested that you print several slightly larger or smaller holes to get what the error is for the printer,, like mine is 4.15mm Radius for an 8mm hole, this leaves just a little snug where as 4mm radius is to small for an 8mm shaft.

webby2

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Re: Printing with PLA
« Reply #7 on: August 08, 2019, 11:35:46 pm »
Here is my new Tronxy in action.
This is the largest single print I have ever done :)    I put the ruler on the bed to show its size

I was having some issues with lifting and stuff,, so I used denatured alcohol to clean the surface and then used some 120 grit sandpaper to sand the entire surface and then clean again with the alcohol.  I also raised the bed temp to 70C instead of 60, the heater element does not go all the way to the edges of the print surface and so the edges of the bed were cooling down to far to hold the print in place.

I also was having print issues that were strange, I would get a shifted print, meaning the print would go for so many layers and then it would suddenly shift in either the X or Y plane and continue.  At first I thought it might be because I was using my computer to serve the print file but I noticed a strange sound every now and then coming from the printer,,,  It was the spool holder position and filament angle of entry into the extruder.  When the spool was on the top of the frame the filament was trying to make a 90 degree turn into the extruder and that port is threaded,, also the spool holder was basically a flat piece of metal that did not allow the spool to roll nicely and what would happen is that every now and then the spool would bind on the holder, that would put to much tension in the filament and that would pull the filament up and into the threads of the port going into the extruder and all of this was just enough to cause the belt to slip a little bit and change the print.
I made a spool holder and it now sits off of the printer and to the side and things are doing way better :)

webby2

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Re: Printing with PLA
« Reply #8 on: August 10, 2019, 11:42:09 pm »
Interesting thing with the Tronxy,,

To print that large print the bed was not holding enough heat out at the far ends to stop the print from warping and lifting,, so I took the suggested setting of 60C and upped it to 70C, this then kept the print stuck to the build surface,, great right ???

Nope,, I have been having fairly good prints off of this thing, they are within about 0.15mm until I upped the bed temp.  At the higher temp the error was up to about 0.3mm but more interesting is that the whole print job was messed up differently,, it was a size thing but the smaller the hole the bigger the impact, the larger the less,, dropped the bed back down to 60C and it seems as tho the issue is not there.
I also have to power cycle the printer from time to time, I start to get a growing error in the Z axis until I power cycle it,, funny little things that to me point to a power supply issue.

 

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