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PaulB
(@paulb)
Trusted Member
What spares should I keep?

Hi,

It looks like I didnt get any spare PTFE tube in my order, so I need or order some. As the shipping is such a significant amount, I want to get other stuff at the ame time. What other things would people suggest I hold in case of failure?

Thanks

Paul

Posted : 18/03/2021 9:45 am
John Doe
(@john-doe-3)
Trusted Member
RE: What spares should I keep?

For me where needed these parts that were better to order more, which Prusa is not offering always

Only Olive rings to hold PTFE tube in extruder and in hotend ... from Ali

PTFE tube one meter ... from Ali

Per type of sheet one, to have per each one spare ... from Prusa

 

Posted : 18/03/2021 10:22 am
PaulB
(@paulb)
Trusted Member
Topic starter answered:
RE: What spares should I keep?

@john-doe-3

Thanks, are they just standard 4mm compression olives? I'm guessing so. Looks like I can get them on eBay pretty cheaply.

Posted : 18/03/2021 10:49 am
JoanTabb
(@joantabb)
Moderator
RE: What spares should I keep?

I keep
a heater,
 Extruder thermistor
Heatbed thermistor
16AWG Flexible silicone wire + 3mm ring and spade crimp terminals (for low voltage Power cable extensions, Heatbed and extruder heater)
24AWG flexile silicone wire  + suitable heatshrink all other signal wires.
spare 0.25mm, 0.4mm, 0.6mm nozzles and a 7mm socket spanner, like they use for 10th scale model car wheel nuts
m3 x 2mm Grub Screw for Bondtech gears and M3 x 3mm for X&Y Motor toothed wheels. plus an assortment of m3 hex head screws (Usually in the Prusa Spares bag)
Spare Build Plates in different surface finishes
Dish soap, Hot water,  clean paper towels 99.9%IPA
and loads of filament

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 18/03/2021 11:08 am
draeh liked
PaulB
(@paulb)
Trusted Member
Topic starter answered:
RE: What spares should I keep?

I guess I should have been clear, I have a mini+ not a MK3.

Thanks

Posted : 18/03/2021 11:18 am
d0ug
 d0ug
(@d0ug)
Trusted Member
RE: What spares should I keep?

For the PTFE tube you need. It would probably be more cost effective to just get a long length of it off ebay/amazon and cut it to size yourself. Prusa has the lengths of the various PTFE tubes on their site. I came across some perfectly clear PTFE tube on amazon months ago and replaced all my tubing with that. Can better see what the filament is doing in the tube rather than the milky tube PRUSA uses. It also seems like that clear tube is ever so slightly narrower inside, giving less play on the filament during retracts. Or the original tube that came with the mini had slightly worn from the filament passing though it. Not sure if that is a thing?

https://www.amazon.com/gp/product/B07TY77KT1/

https://help.prusa3d.com/en/guide/how-to-trim-ptfe-tube-original-prusa-printers_22424#133076

Posted : 19/03/2021 1:49 am
d0ug
 d0ug
(@d0ug)
Trusted Member
RE: What spares should I keep?

For the crush washers. I would just recommend completely removing the crush fittings and replacing them with these PC4-M8 fittings. You just push the PFTE tube into them and there are teeth inside that bite into the tube to keep it from coming out. You push down on the blue part to release the teeth to pull the tube out. The inside part of the fitting is not as deep as the original crush fittings. You'll need to modify the length of the tubing inside the hot end and extruder. The ones I got measured about 2.72mm shallower than the original fittings. So you'll need to cut those tubes 2.27mm shorter than the specs on PRUSA's site

https://www.amazon.com/gp/product/B07QFK7YWP/

I went with these after twice the crush fittings slipped and the PTFE tube slipped out. I got to the point I was making a mark on the PTFE tube where it entered the fitting so I could see if it was slipping again. Absolutely no issue with those replacement fittings since replacing them Nov last year.

 

Posted : 19/03/2021 2:05 am
d0ug
 d0ug
(@d0ug)
Trusted Member
RE: What spares should I keep?

Also for cutting the long tube that goes between the extruder and the hot end, I don't think the length of this tube is as crucial. As long as it is long enough to give the axis movement along it's whole length, but not so excessively long that the amount of time the extruder retracts during a filament change allows the filament to fully extract and clear the extruder teeth. The extruder essentially zeros out any variance of this length on filament load when it is done purging.

Posted : 19/03/2021 2:19 am
PaulB
(@paulb)
Trusted Member
Topic starter answered:
RE: What spares should I keep?

@d0ug

Thanks for the suggestions, i'll look into it. How do you manually cut the chamfers on the PTFE? Is there a tool?

 

Posted : 19/03/2021 9:05 am
JoanTabb
(@joantabb)
Moderator
RE: What spares should I keep?

@d0ug

there is an issue with the Pneumatic  fittings, 
the repeated movement of the X axis carriage causes the teeth in the fitting to saw through your PTFE Tube  and will eventually cut the end off... 
this was a problem on MMU1 and MMU2

regards Joan

 

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 19/03/2021 9:47 am
John Doe
(@john-doe-3)
Trusted Member
RE: What spares should I keep?
Posted by: @d0ug

For the crush washers. I would just recommend completely removing the crush fittings and replacing them with these PC4-M8 fittings.

The reason, Prusa use this is because, the PETF tube rotates in all directions due to way how it operates. So it is not a good idea to replace them for the pressured one. I already had to twice cut from PETF tube (per 1cm) because due to pressure it slide out and was "damaged" where the holding was.
I am using it for now on one side as on the picture, only because I don't have a spare one (waiting for ali-ex to deliver a bunch of the olive rings).

Posted : 19/03/2021 11:15 am
d0ug
 d0ug
(@d0ug)
Trusted Member
RE: What spares should I keep?

@paulb

I didn't bother with the outside ones. The inside ones I used a cone shaped grinding stone that I have for my dremel. Push the tip of the cone into the tube for a few seconds and done. Just make sure to use some compressed air to blow the grindings out of the tube afterwords.

Posted : 19/03/2021 1:16 pm
d0ug
 d0ug
(@d0ug)
Trusted Member
RE: What spares should I keep?

@joantabb

Hmm, It's not been an issue for me yet, and going on about 4.5 months they have been installed. Longer than before I started having issues with the stock fittings. I'll pop the tube out after my current print finishes and see if it is chewing into the tube. Easy enough to replace the tube every few months since I have several feet of the stuff here. Much less hassle than those compression fittings.

Posted : 19/03/2021 1:19 pm
JoanTabb
(@joantabb)
Moderator
RE: What spares should I keep?

 I had the MMU1 it had 4 tubes to the extruder so there were 8 pneumatic connectors chewing up the PTFE tubes...    
they were the 5mm thread ones, so there was no way to get the ends out of the connectors when they got cut off... 

really frustrating!

the MMU2 has one tube and two fittings

the main difference is the MMU1 and MMU2 have the X axis passing left to right in front of them, the Mini has the X axis moves towards and away from the extruder... so that may make a difference... 

regards, Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 19/03/2021 3:45 pm
d0ug
 d0ug
(@d0ug)
Trusted Member
RE: What spares should I keep?

So I just got to inspecting my tube today and yes it does look like the teeth chewing into the tube is an issue. Not as much on the hot end side because it would seem that mainly sees back and forth movement, but more so on the extruder end because of the angle of that fitting it sees more of a twisting motion. My tube hadn't chewed all the way though, but was pretty deep in. I just replaced the tube and cut the replacement about an inch longer. I will just add inspecting the tube to my routine inspection and maint of the printer and with the slightly longer cut tube I can just cut off the chewed up ends a few times before the tube gets so short I just need to replace the whole thing.

Considering that one lasted me about 4 months with zero issues. I would still rather use those fittings than use the compression fittings. I am more confident that those fittings aren't going to just pop out like the compression fittings. Last thing I want is a day long print fail because the tube poped out while I was asleep and then just have a mess of filament to back though the extruder or cut off and toss away if it doesn't just get tangled around everything and cause larger issues.

In the end the PTFE tubing is cheap enough that I'd just rather regularly replace it than have to constantly worry about those compression fittings.

If anything as well, the chewing just means the tube becomes even more secure, because now the teeth are in a notch that they have dug into the tube making it even less likely that it just pops out.

Posted : 22/03/2021 2:32 am
cwbullet
(@cwbullet)
Illustrious Member
RE: What spares should I keep?

I keep, one bed, one hotend, one hotend thermistor, one bed thermistor, one print fan, one hotend fan, and one heater.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 22/03/2021 5:10 pm
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