understanding the plastruder mk4
Craig Link
understand some of the skeinforge settings, but I’ve just deformed my
second PTFE barrier and had ABS oozing from the threads. I’m sure
some of this is by squishing rafts occasionally too much, etc., but
there should be a way to reduce the heat deformation. I have a PEEK
insulator on order.
After I deformed my first one, I did a bit of reading an saw one post
where a small fan was mounted on the Z-axis acrylic near the PTFE
barrier. I installed a 20mm CPU fan and ran my bot this way for a
bit. Unfortunately it was blowing a bit low with some air going just
below the laser cut washer and causing some print issues. I think was
causing to short of a thermal transition for the ABS. Side note –
when I had the fan running it would drop the temperature of my nozzle
by 4c to 216c and keep it there while running.
So I played with manually turning the fan on and off a bit while I was
getting ready to print, but not actually printing. It worked well but
became tiresome. So eventually, I turned it off – and soon after I
deformed my second PTFE barrier.
Before I go into a bunch of experimentation, I’d see what knowledge is
out there.
Besides being a mechanical support, what purpose does the laser cut
washer server? Is it a heat sink for cooling? Or does it help the
regulate temperature. Just wondering if I should avoid cooling it at
all.
The nut which buts up against the PTFE barrier. I believe this is
just structural to remove upward stress from barrel on the PTFE.
However, being steel, this is transferring heat to the PTFE. Would it
make sense to install an insulating material between the two. I’m
thinking of making a large washer out of a FR4 circuit board that I
have lying around.
What about the thermal transition arrange along the length of the PTFE
barrier. Is it bad to cool the whole length? At what point does the
Plastuder expect the ABS to begin to be warmed / heated? Would
blowing a fan on the upper part of the PTFE barrier be bad?
Thanks
-Craig
MakerBot #545
Steven Dick
[...]
Besides being a mechanical support, what purpose does the laser cut
washer server? Is it a heat sink for cooling? Or does it help the
regulate temperature. Just wondering if I should avoid cooling it at
all.
I don't know if it was intenteded as a heat sink but I found it does work as one.
Steel is a relatively poor thermal conductor as metals go, so it doesn't suck all the heat out, and even if the washer is hot, you'll notice the screws are a lot cooler at the other end.
I actually have a jam nut both above and below the washer to keep it from wiggling, and I found that with both nuts, the washer wass sinking too much heat. I put a few layers of kapton tape in to reduce the cooling, and that worked well. However, I found that if I put two much insulation, I get melting like you describe, so apparently some amount of heat sinking on the copper barrel helps.
The nut which buts up against the PTFE barrier. I believe this is
just structural to remove upward stress from barrel on the PTFE.
However, being steel, this is transferring heat to the PTFE.
On my plastruder, there is a narrow gap between the nut and the PTFE -- it can't really effectively relieve stress if it is putting pressure on the PTFE!
What about the thermal transition arrange along the length of the PTFE
barrier.
I think this is more critical with PLA than ABS. Some people have actually put heat sinks on the PTFE.
Tony Buser
> The nut which buts up against the PTFE barrier. I believe this is
> just structural to remove upward stress from barrel on the PTFE.
> However, being steel, this is transferring heat to the PTFE. Would it
> make sense to install an insulating material between the two. I’m
> thinking of making a large washer out of a FR4 circuit board that I
> have lying around.
I like to put a bit of PTFE cut off a ruined barrel between the nut
and the washer to help reduce heat transfer like this:
http://www.flickr.com/photos/tbuser/4374053726 I've also been
experimenting with using a slice of threaded PEEK in place of a metal
nut. It seems to be almost strong enough to serve the same structural
support that a nut does without changing the heat profile at all, see:
http://www.flickr.com/photos/tbuser/4455825211
Thomas Charron
What about the thermal transition arrange along the length of the PTFE
barrier. Is it bad to cool the whole length? At what point does the
Plastuder expect the ABS to begin to be warmed / heated? Would
blowing a fan on the upper part of the PTFE barrier be bad?
--
-- Thomas
Rick Pollack
With the tip at 220C you'll find the temp at top of the barrel to be 180C - 190C IIRC (plus or minus) depending on how well the nichrome is wrapped and how much heat is being lost - primarily due to the large washer. The problem is not that the top of the barrel is too hot, rather if the temp at the top of the barrel drops below ~180C ABS filament gets stuck in the barrel. When the filament gets stuck the motor is still pushing and this forces softened filament to expand sideways and is likely the reason for damaged PTFE insulators and ABS in the threads. Even when the plastruder seems to be working but the temp is still borderline, softened ABS still gets forced sideways into the threads. Get the temp properly managed and PTFE insulators can last a long time (though for ABS, PEEK is really the way to go).
PLA 4042D needs a barrel entry temp of 150C. PLA 4032D has a 10C higher melting temp than 4042D, so it probably needs 160C.
Here are photo sets of ABS and PLA melt processes taken using a glass plastruder.
Rick
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Thomas Charron
Thomas -
With the tip at 220C you'll find the temp at top of the barrel to be 180C - 190C IIRC (plus or minus) depending on how well the nichrome is wrapped and how much heat is being lost - primarily due to the large washer
The problem is not that the top of the barrel is too hot, rather if the temp at the top of the barrel drops below ~180C ABS filament gets stuck in the barrel. When the filament gets stuck the motor is still pushing and this forces softened filament to expand sideways and is likely the reason for damaged PTFE insulators and ABS in the threads. Even when the plastruder seems to be working but the temp is still borderline, softened ABS still gets forced sideways into the threads. Get the temp properly managed and PTFE insulators can last a long time (though for ABS, PEEK is really the way to go).
PLA 4042D needs a barrel entry temp of 150C. PLA 4032D has a 10C higher melting temp than 4042D, so it probably needs 160C.
Here are photo sets of ABS and PLA melt processes taken using a glass plastruder.
Rick
On Tue, Apr 6, 2010 at 11:17 AM, Thomas Charron <twa...@gmail.com> wrote:On Sun, Apr 4, 2010 at 1:54 PM, Craig Link <make...@moonrock.com> wrote:
What about the thermal transition arrange along the length of the PTFE
barrier. Is it bad to cool the whole length? At what point does the
Plastuder expect the ABS to begin to be warmed / heated? Would
blowing a fan on the upper part of the PTFE barrier be bad?The primary thought of the insulator is to be able to hold onto something hot, and connect it to something cold. Here, in my opinion, if the flaw in that plan.There is much talk about a thermal gradiant, heating the barrel twards the tip, and have it be cooller up by the insulator. This is, IMHO, a fundamental flaw. You see, the barrels and made of brass, which is one of the best thermal conductors that could be put into the bot. So when the tip is heated to 220 degrees, you can bet that the top of that barell is pretty close to that as well.When this occurs, and your not printing, the ABS twards the top of the barell begins to melt. When this occurs, there is a larger pressure area once you start pushing ABS once again. At this point, the pressure area begins to extend into the thermal insulator itself, which is not meant to BE part of the barell. Proof that this occurs is that when people are blowing out their insulators, they find moltel ABS has krept into the threads.The 'proper design' would insulate the barel be using a two of three peice barel. These peices would be connected by a thermal insulator, such as ceramic.--
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Rick Pollack
How the barrel is wrapped is of primary importance. And, like I said, heat loss up the barrel results primarily from having a large washer on the barrel. Get rid of the washer, insulate the barrel and most of the heat loss goes away.
The glass was heated all the way up, you can see the nichrome wrapped around the glass.
"If there is a thermal insulater as part of the barrel, it functions much better." Do you have something working?
Rick
wulfdesign
I've "armored" my PTFE insulator by cutting a 1/2 inch copper pipe
coupler lengthwise and putting a hose clamp around it.
completely solved the whole PTFE bulging issues.
Larry James
Wulf Design
http://wulfdesign.blogspot.com
On Apr 6, 9:47 am, Rick Pollack <r...@makergear.com> wrote:
> Thomas -
>
> How the barrel is wrapped is of primary importance. And, like I said, heat
> loss up the barrel results primarily from having a large washer on the
> barrel. Get rid of the washer, insulate the barrel and most of the heat loss
> goes away.
>
> The glass was heated all the way up, you can see the nichrome wrapped around
> the glass.
>
> "If there is a thermal insulater as part of the barrel, it functions much
> better." Do you have something working?
>
> Rick
>
> On Tue, Apr 6, 2010 at 12:23 PM, Thomas Charron <twaf...@gmail.com> wrote:
> > On Tue, Apr 6, 2010 at 12:11 PM, Rick Pollack <r...@makergear.com> wrote:
>
> >> Thomas -
>
> >> With the tip at 220C you'll find the temp at top of the barrel to be 180C
> >> - 190C IIRC (plus or minus) depending on how well the nichrome is wrapped
> >> and how much heat is being lost - primarily due to the large washer
>
> > Brass has a thermal conductivity of 109. This conductivity functions
> > both ways. When performing measurements using MakerGears thermistors when
> > the barrel is not actually screwed into an insulator, and the thermistor
> > head itself was insulated, and in direct contact with the brass barrel, I've
> > seen a 5 degrees C variance. Not 40.
>
> >> The problem is not that the top of the barrel is too hot, rather if the
> >> temp at the top of the barrel drops below ~180C ABS filament gets stuck in
> >> the barrel. When the filament gets stuck the motor is still pushing and this
> >> forces softened filament to expand sideways and is likely the reason for
> >> damaged PTFE insulators and ABS in the threads. Even when the plastruder
> >> seems to be working but the temp is still borderline, softened ABS still
> >> gets forced sideways into the threads. Get the temp properly managed and
> >> PTFE insulators can last a long time (though for ABS, PEEK is really the way
> >> to go).
>
> >> PLA 4042D needs a barrel entry temp of 150C. PLA 4032D has a 10C higher
> >> melting temp than 4042D, so it probably needs 160C.
>
> >> Here are photo sets of ABS<http://www.flickr.com/photos/makergear/sets/72157622855375537/>and
> >> PLA <http://www.flickr.com/photos/makergear/sets/72157623457543310/> melt
> >> processes taken using a glass plastruder.
>
> > Using a glass barrel, which has a thermal conductivity rating of around
> > 2, as compared to brass or even aluminum. In a way, your images validated
> > what I was saying. If there is a thermal insulater as part of the barrel,
> > it functions much better.
>
> >> Rick
>
> >> On Tue, Apr 6, 2010 at 11:17 AM, Thomas Charron <twaf...@gmail.com>wrote:
> >>> makerbot+u...@googlegroups.com<makerbot%2Bunsu...@googlegroups.com>
> >>> .
> >>> For more options, visit this group at
> >>>http://groups.google.com/group/makerbot?hl=en.
>
> >> --
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> > --
> > -- Thomas
>
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othreed
I have a ABS build up problem inside the PTFE barrier right above the
brass barrel .. Can anyone point out a solution please.. Should the
temperature at the top of the extruder barrel right where it connects
to the PTFE Barrier be hot or cold? Seems as if there are different
opinions about that.
please take a look at these photos on flickr .. This is what happens
to my every time .. even after 7 - 10 min heat up at 220 C
http://www.flickr.com/photos/49144859@N04/4505201916/
I did not measure the temperature but I think that it quite hot
because the "teeth" in the ABS get meltet away.
http://www.flickr.com/photos/49144859@N04/4504805183/
thanks for any help
On Apr 9, 10:37 am, wulfdesign <wulfdes...@gmail.com> wrote:
> just a quick note.
>
> I've "armored" my PTFE insulator by cutting a 1/2 inch copper pipe
> coupler lengthwise and putting a hose clamp around it.
>
> completely solved the whole PTFE bulging issues.
>
> Larry James
> Wulf Designhttp://wulfdesign.blogspot.com
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>
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> > > --
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>
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Roger Walsberg
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Thanks. Roger
Andrew Plumb
Andrew.
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othreed
is all close to the nozzle like described in the instructions.
Also I put the big nut on the PTFE side just as described in the
assembly instructions
http://wiki.makerbot.com/plastruder-mk4-assembly
"slide on the washer, thread the M6 nut snug against the washer and
then screw the PTFE Thermal Barrier Back on. "
Can anyone confirm that the brass nozzel has to be hot right up to the
PTFE barrier or does is need to be colder?
thanks
On Apr 9, 4:20 pm, Andrew Plumb <and...@plumb.org> wrote:
> That big nut you have on the PTFE side of the retainer washer is going to drastically change the thermal properties of the PTFE-side of the barrel. Even more if it's not insulated; it'll act like a heat-sink and the PTFE-insulated part of barrel won't get warm enough to melt that chunk of melted ABS.
>
> Andrew.
>
> On 2010-04-09, at 10:06 AM, Roger Walsberg wrote:
>
>
>
>
>
> > Where is your heater wire relative to the brass tube? I wound mine closest to the tip, and not up the barrel. I don't have the problem you are having.
>
> > > > >>> makerbot+u...@googlegroups.com<makerbot%2Bunsubscr...@googlegroups.c om>
> > > > >>> .
> > > > >>> For more options, visit this group at
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>
> > > > >> --
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> > > > > --
> > > > > -- Thomas
>
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> > --
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> > --
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>
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Andrew Plumb
Ah, the other important detail is to measure the size of your thermistor and pick the correct look-up table in ReplicatorG. Sensed 220C may not actually be 220C if the look-up tables are wrong for your particular thermistor.
Andrew.
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Steven Dick
have a problem with ABS building up above the brass barrel inside
the PTFE barrier. It seems as if there are different opinions about a
hot or colder top of the brass barrel. What is right?
please take a look at these pictures..
Any suggestions?
http://www.flickr.com/photos/49144859@N04/4504805183/
http://www.flickr.com/photos/49144859@N04/4505201916
From the pictures, I'd guess your PTFE is stretched on the inside.
Put a piece of raw filament in it and compare the size of the hole where it meets the brass barrel.
The filament is suppose to be 2.9 - 3.0 mm in diameter, and the hole is suppose to be 3.1mm.
It looks to me like the small hole has been stretched to the size of the large hole.
othreed
What did I do wrong?
Searching forum, group and net brings up a lot of problems with the
PTFE... guess I will have to go for PEEK..
Any suggestions?
On Apr 9, 7:50 pm, Steven Dick <kg4...@gmail.com> wrote:
Steven Dick
Yes, it is streched inside where the PTFE meets the Brass barrel...Any suggestions why this happened?
The stretched barrel will continue to cause more jams.
My experience is that problems with the plastruder cause more problems with the plastruder.
When it works, it works great and long. When it breaks, it breaks more faster.
Probably somthing you did in the past caused a jam, and either the jam caused the stretching directly, or you backed out a stiff blob backwards and stretched the insulator. I've done this myself, it's hard to prevent. Sometimes the best bet is to unscrew the support bolts and run it forward until you can cut the filament, remove the insulator (and then inspect the filament where the insulator and barrel join), heat it back up to remove the filament. Its a lot easier to just back it out without dissassembling it though.
The most likely reason for a blob to form between the barrel and the insulator is that you didn't screw the insulator in far enough.
I found a better way to assemble the extruder head is to first put a piece of raw filament all the way through the insulator, and then screw the barrel into it as far as it will go. The filament in the insulator will keep it from collapsing as you screw it in hard. (If you go too far, you mash the bottom of the lip and shrink the hole too much.)
Now that I think about it, this probably should go in the wiki -- is anyone else using this method to protect the insulator during assembly?
Cathal Garvey
I have just managed to do the same to my extruder, just days before an ignite talk I'm supposed to be giving on Makerbot. Wanted to have it printing at the talk..
Any suggestions for a quick and desperate insulator?
On Apr 10, 2010 5:28 AM, "Steven Dick" <kg4...@gmail.com> wrote:On Fri, Apr 9, 2010 at 2:37 PM, othreed <ole.h...@gmail.com> wrote: > > Yes, it is streched insid...
The stretched barrel will continue to cause more jams.
My experience is that problems with the plastruder cause more problems with the plastruder.
When it works, it works great and long. When it breaks, it breaks more faster.
Probably somthing you did in the past caused a jam, and either the jam caused the stretching directly, or you backed out a stiff blob backwards and stretched the insulator. I've done this myself, it's hard to prevent. Sometimes the best bet is to unscrew the support bolts and run it forward until you can cut the filament, remove the insulator (and then inspect the filament where the insulator and barrel join), heat it back up to remove the filament. Its a lot easier to just back it out without dissassembling it though.
The most likely reason for a blob to form between the barrel and the insulator is that you didn't screw the insulator in far enough.
I found a better way to assemble the extruder head is to first put a piece of raw filament all the way through the insulator, and then screw the barrel into it as far as it will go. The filament in the insulator will keep it from collapsing as you screw it in hard. (If you go too far, you mash the bottom of the lip and shrink the hole too much.)
Now that I think about it, this probably should go in the wiki -- is anyone else using this method to protect the insulator during assembly?
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Andrew Plumb
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wulfdesign
I've found that it's easy enough to OVER tighten
it and cause too much pressure/shrink the 3m hole/ deform it.
enough to cause it too jam.
cutting a piece of 1/2 in copper pipe coupling lenght wise with a
hacksaw
and then clamping the bejesus out of it (use solid marine grade
Stainless hose clamp or 2)
will keep it from getting deformed without crushing it.
it'll probably work an an already bulged PTFE (though I haven't tried
that yet)
to bring it back into a usable state. (especially if you heat it up
some to get the PTFE soft.)
good luck and let us all know if it worked out.
-L
p.s. I think someone else called this "Armoring" their Plastuder...
On Apr 10, 8:55 am, Andrew Plumb <and...@plumb.org> wrote:
> Maybe try this:
>
> 1. Wrap one of those screw-tightened pipe clamps around the PTFE
>
> 2. Insert the brass barrel
>
> 3. Crank up the heater; don't know what target temp but perhaps
> something like 230C or 240C to make it softer than normal.
>
> 4. Gradually tighten the clamp screws until it's back to it's regular
> outer diameter.
>
> 5. Check internal clearance with a 3mm or 1/8" drill bit.
>
> 6. Keep the pipe clamp in place for actual printing.
>
> Andrew.
>
> On 2010-04-10, at 10:31, Cathal Garvey <cathalgar...@gmail.com> wrote:
>
> > I have just managed to do the same to my extruder, just days before
> > an ignite talk I'm supposed to be giving on Makerbot. Wanted to have
> > it printing at the talk..
>
> > Any suggestions for a quick and desperate insulator?
>
> >> On Apr 10, 2010 5:28 AM, "Steven Dick" <kg4...@gmail.com> wrote:
>
> >> On Fri, Apr 9, 2010 at 2:37 PM, othreed <ole.hein...@gmail.com>