Teflon spacer replacement

[densohax 0]

I just read about vespel, sounds like a good material! Do you have a good place where we can source this from Canada or US ?

 

[3poro 9]

As Vespel's availability is not great - and as its price is prohibitive, I would like to share some of mine with those who inspired me to make my move... With all respect for everyone following this thread, I'm addressing this message to Anders Olsson, Cleven, densohax, Kris and Solid Print 3D (in alphabetical order).

I have three "surplus" washers made out of Vespel:

 

1. 3.5mm thick (good fit to stainless steel isolator, diameter 6.3mm)
    
   
2. 2.4mm thick (same as above)
    
   
3. 2.3mm thick (slightly loose fit to stainless steel isolator, diameter 6.1mm)
   

 

If you would like to get one of the washers above, please respond to this thread indicating which one you would like to get. First-come, first-served. No costs for you, except a humble wish that you would share your experiences afterwards.

In case one of you would want to use some of my remaining Vespel rod instead, let me know. This offer is valid only if you are located within the European Union - and you have a lathe - and you are ready to make some charity crafting for the other contributors

 

[densohax 0]

Unfortunately, I live in canada, but if you accept that I pay the shipping, I'd be happy to have #1!

 

[3poro 9]

Unfortunately, I live in canada, but if you accept that I pay the shipping, I'd be happy to have #1!

 

I don't think you are very unfortunate, at least for living in Canada

Sorry for being unclear - I didn't mean I wouldn't mail the washers outside of the European Union. It's the Vespel rod I don't want to send outside of the EU as its value is too high. If Canadian customs wouldn't collect any duties on it, the Soviet European Union certainly will once the rest of it would be returned to me.

On the other hand, as Vespel is (somewhat) more affordable in the US (through Amazon, as I wrote above), it doesn't make sense to send the stuff over from the Tax Heights (EU).

So - you'll get #1 if you just send me your mailing address as a private message. No need to pay for shipping, unless you require some super express delivery.

 

[densohax 0]

I don't think you are very unfortunate, at least for living in Canada

Sorry for being unclear - I didn't mean I wouldn't mail the washers outside of the European Union. It's the Vespel rod I don't want to send outside of the EU as its value is too high. If Canadian customs wouldn't collect any duties on it, the Soviet European Union certainly will once the rest of it would be returned to me.

On the other hand, as Vespel is (somewhat) more affordable in the US (through Amazon, as I wrote above), it doesn't make sense to send the stuff over from the Tax Heights (EU).

So - you'll get #1 if you just send me your mailing address as a private message. No need to pay for shipping, unless you require some super express delivery.

 

Oh I misread that post!

Ok I'll send you a pm as soon as I get home, thanks a lot!!

 

[Anders Olsson 136]

The #2 would work fine for me, I am happy to have that one if still available. :smile:

I will PM more info.

 

[solid-print-3d 30]

Torlon 4301

Torlon 4435

ALTYMID® 750

Meldin 7001

Meldin 6000

Duratron® PBI

Plavis N

These are the Vespel alternatives I've found so far. Interestingly enough, they all have a glass transition phase, whereas Vespel is stated as having no observable Tg by some. For instance the Tg of Torlon 4301 is 280C, but is rated up to 260C. Will have to do some more research on these.

 

[3poro 9]

Right - densohax and Anders have been sent some Vespel... Washer #3 above is still up for a grab. Don't let the "loose fit" note fool you; if requested, I can also send some polyimide tape with the washer.

 

[densohax 0]

Very nice of you 3Poro, thanks again!

 

[Anders Olsson 136]

I pricked up the Vespel spacer today, thanks again 3Poro!

To get some idea of how it reduces the temperature of the remaining teflon spacer, I modified an old teflon spacer (not glass filled) to fit a temperature sensor.

This teflon spacer was in bad condition already before I modified it, and making room for the temperature sensor did not improve it :???: So I don't know how realistic this test was, but hopefully it should give some idea about the improvement.

I printed the Ultimaker robot in ABS at 260C, but I had to abort the print half way through because I was lazy to level the platform and the robot came loose.

Anyway, the temperature had then stabilized at about 80C.

Impressive so far, I have to say!!

The current teflon spacer has suffered form previous experiments and has an inner diameter of 3.5mm , so I can not really conlude anything about retraction with this one (it worked, but showed potential for problems).

Next test will be to fit another glass filled spacer with normal inner diameter and crank up the temperature to polycarbonate levels :grin:

 

[3poro 9]

Great stuff - as I wasn't analytic (or diligent) enough to use temperature probe, I'm very glad to get some numbers - thank you for sharing!

I would guess the temperature drops quite nicely by every millimeter of insulator - and the good news is, it doesn't actually have to drop a lot. In the original design the Teflon is in direct contact with 260C brass.

 

[Anders Olsson 136]

I did some more testing of the Vespel insulator tonight.

Initially it caused me quite some problems with PLA, but this was mainly related to the fact that my teflon spacer had 0.1 mm larger inner diameter than the Vespel insulator which caused major problems after retraction.

After I drilled it to 3.3 mm it appears to be printing PLA fine.

However, I still have a feeling that the Vespel causes some friction with PLA and that making it thinner would reduce friction.

I managed to get a molten plug of ABS to stick inside the Vespel insulator too. (before I increased the inner diameter of it)

I was worried that the ABS would bond to the Vespel since it was sitting there for quite some time at 260C before slowly cooling down.

But the ABS-plug came out easily and did not show any signs of bonding to the Vespel.

So apparently Vespel does not bond easily to ABS even though it chemically is a kind of polyimide.

 

[Anders Olsson 136]

I have been printing Polycarbonate at 290-300C for about 6 hours now with the Vespel insulator.

I had to stop since there was a strong smell of burnt plastic and I had to find out what was going on.

It turns out there was a leak somewhere in the Vespel-area which soaked my heater block in polycarbonate :cry:

 

The leak was most likely caused by one of the surfaces not being perfectly flat. I will investigate this further.

When taking things apart I noticed that the teflon spacer seems to have survived the increased temperature:

The slightly burnt surface on the teflon comes from numerous hour of printing before cut 2mm of the teflon spacer to fit the Vespel insulator.

If anyone else ends up soaking the heater block in polycarbonate, I found out that burning it off with a micro torch works well (obviously has to be done outdoors, with sensor, heater and teflon spacer removed)

Considering Vespel, I think I just found another alternative that looks interesting.

It is commonly known as Kalrez, Isolast or Perlast and chemically called "perfluoroelastomer" or FFKM.

It is used for o-rings and some grades have continous operating temperatures of up to 327C (!)

I think an o-ring like that might be the ultimate thing to put between the teflon insulator and the heater block. It will serve both as a heat break and as a seal, reducing both thermal stress on the teflon and reducing the risk of leaks of molten plastic.

These Kalrez o-rings seems to be as pricey as Vespel though, and I had difficulties finding an o-ring with suitable size.

 

[gadgetfreak 7]

Excellent experimenting Anders!!

[donmilne 2]

I would have thought you need a washer rather than an O-ring. With an O-ring thing will be a rib of PLA which if allowed to cool will prevent you from changing filaments.

 

[3poro 9]

Great to see the washer has been taken into use by a real overclocker! Were you using "plain" PTFE isolator or the newer glass-impregnated one? I have only used the plain one as it feels softer and I thought it would act as a kind of a seal. Having an additional part/material on the filament path is of course not ideal...

What comes to the print after 6 hours, how was the print quality until that point? I would be very interested in printing PC as well, if your findings are encouraging.

 

[densohax 0]

On my side, I didn't test the vespel yet, my setup is not failing, even in an enclosure..

 

I'm planning heavy printing soon, so we'll see if I need it! If I don't need it, I will be happy to send the vespel to someone who needs it.

Here's something I'm currently designing and will be printed soon (home made bearings, electroformed plastic and hopefully diy hydraulics (I'm trying to polish an ABS copper-electroplated liner that will fit in my cylinders) )

 

Here's my enclosure setup btw, I will need ventilation for the bottom PCB. (I still don't understand why the red tubing of my MK6 is not failing)

 

 

[Anders Olsson 136]

DonMilne >> Yes, a flat FFKM-gasket would be better than an o-ring, but flat FFKM gaskets seems even more uncommon than o-rings.

I think a thin O-ring would work, since it sits very close to the heat block which means the plastic stays reasonable soft there.

3Poro >> I used a glass filled teflon isolator. The only pure teflon isolator I had ended up too heavily modified for further use when I fitted the temperature sensor to it.

As I mentioned, I suspect one of the parts is not perfectly flat and that is why it was leaking, I will have a look into that.

Polycarbonate is quite tricky. I struggled to get reasonable layer adhesion but my destructive testing always ended up in things coming apart between the printed layers.

On the other hand, I tested an ABS component in the same way and PC printed hot was obviously stronger.

Printing hot and slow seems to help and PC prints quite nicely actually. Drying the filament in an oven at 120C for a few hours improves printing quality a lot too.

I think there should be a combination of tricks that prints PC nicely in the UM2, but I have to keep testing to figure the parameters out.

PC printing is on hold right now though, until I found out why it was leaking.

 

[densohax 0]

On the other hand, I tested an ABS component in the same way and PC printed hot was obviously stronger.

Printing hot and slow seems to help and PC prints quite nicely actually. Drying the filament in an oven at 120C for a few hours improves printing quality a lot too.

 

Is PC as stiff as PLA or flexible like ABS ?

 

[Dim3nsioneer 557]

CDs / DVDs / BDs are made of PC...

 

[MartijnvG 16]

I bought Vespel from Goodfellow (http://www.goodfellow.com), but there are probably cheaper sources... In the US, Vespel can even be ordered from Amazon with quite reasonable cost:

http://www.amazon.com/Vespel-Round-Opaque-Diameter-Length/dp/B00FKK36LU

I'm wondering when Ultimaker will announce something based on Vespel. When people have proposed Aerogel, ceramics and metals, Ultimaker engineers have made comments on those materials. Vespel has also been proposed, but there's been complete silence from Ultimaker's side. I'm drawing conclusions and wearing a folio hat.

 

Hi guys,

sorry i have been a little quiet lately, busy times at the hq. But i have to say i love the work you guys have been doing and i'm very impressed. I'm very curious how the vespel has been holding up. I am actually thinking of ordering some here and running some tests with it for dual extrusion on the UM2, the problem with that is the deformation in the PTFE occurs faster as soon as you add the second Hot-end in the printhead. So actively cooling them with a 35mm fan on the front (and removing the small fan at the back for better airflow). I am however still a little afraid that is not enough to prevent the PTFE from deforming. So thats why i turn to the Vespel.

@kris, I really like your idea's with the extra cooling ribs on the steel coupler, and i love your heat simulations. i want to look at your idea as a backup if the vespel doesn't make it as a good fix because it changes more parts in the whole print head.

So if you want and can i would really like to your idea's and opinions.

 

[3poro 9]

I'm very curious how the vespel has been holding up. I am actually thinking of ordering some here and running some tests with it for dual extrusion on the UM2, the problem with that is the deformation in the PTFE occurs faster as soon as you add the second Hot-end in the printhead. So actively cooling them with a 35mm fan on the front (and removing the small fan at the back for better airflow). I am however still a little afraid that is not enough to prevent the PTFE from deforming. So thats why i turn to the Vespel.

 

Vespel seems to hold up pretty well. I ended up making a pretty extreme test a few days ago - unintentionally. Here's how the story went... My UM2 has had some connector contact issue from its early days, causing the rear fan to stop breathing every now and then - but only for a second or two at a time. I noticed the issue maybe once a week or two, so I didn't pay too much attention on it. However, I have always wondered what would happen if the rear fan just stopped functioning. In my case this would mean stopping the two powerful Tornado fans I have installed to replace the original Sunon fan. As I typically print at 260C and I have a closed chamber, maybe heat would cause some damage?

A few days ago, due to human error (rather than poor connector contacts of my UM2), I was printing having the "rear fan" turned off completely. After several hours I noticed the print had failed and the filament was stuck somewhere in the print head. I had to open the print head to get my printer serviced. The last centimeters of the filament had grown in size - enough to cause the blockade. Obviously the filament had had problems with the increased temperature. However, both the PTFE and the Vespel parts were in perfect condition. No burnt surfaces, no ridges - nothing. I just had to reassemble the print head, cut the first few centimeters off the filament and continue printing.

My guess is - there is no need to modify the stainless steel insulator or to make some dramatic changes to cooling. The problems with PTFE are caused by the part being in direct contact with the hot nozzle. As soon as there's some "cushion" between the two, there's immediate improvement.

 

[Anders Olsson 136]

I'm very curious how the vespel has been holding up. I am actually thinking of ordering some here and running some tests with it for dual extrusion on the UM2, the problem with that is the deformation in the PTFE occurs faster as soon as you add the second Hot-end in the printhead.

 

If heat-related deformation of the PTFE insulator is the main problem with dual extruders I think a short Vespel spacer might work.

I though another major heat problem with dual extruders was that PLA will melt further up the PTFE insulator when both extruders are heated, causing retraction issues?

Personally, I would really like to get a sheet or a suitable diameter o-ring made from FFKM (Kalrez).

I think that material has a combination of properties which makes it even more promising than Vespel, even though Vespel is not bad at all.

It seems even more difficult to get FFKM than Vespel though..

Regarding Duratron, I had a talk to our workshop, but they kind of did not like what they read about machining that stuff.

So I have abandoned that material for now.

 

[MartijnvG 16]

If heat-related deformation of the PTFE insulator is the main problem with dual extruders I think a short Vespel spacer might work.

I though another major heat problem with dual extruders was that PLA will melt further up the PTFE insulator when both extruders are heated, causing retraction issues?

Personally, I would really like to get a sheet or a suitable diameter o-ring made from FFKM (Kalrez).

I think that material has a combination of properties which makes it even more promising than Vespel, even though Vespel is not bad at all.

It seems even more difficult to get FFKM than Vespel though..

Regarding Duratron, I had a talk to our workshop, but they kind of did not like what they read about machining that stuff.

So I have abandoned that material for now.

 

Getting specialized plastics is not easy, so i found a show where they machine vespel and i'm trying to order some rings with different diameters.

About the material getting to hot and plugging during lots of retractions. i have been actively cooling the hot-ends with a 35mm fan and fan duct on the front as well. The combination should reduce the overall heat in the hot-end and prevent that from happening.

its a work in progress, but i think we are getting somewhere

 

[3poro 9]

About the material getting to hot and plugging during lots of retractions. i have been actively cooling the hot-ends with a 35mm fan and fan duct on the front as well. The combination should reduce the overall heat in the hot-end and prevent that from happening.

 

The problem with two hot-ends and retractions has been discussed in some other threads as well, but I'm pretty confident that issue is not very difficult to solve. Cooling of the print head needs to be enhanced, but the original design leaves quite clear room for improvement - without redesigning the whole thing. While I have improved the cooling by ignoring noise levels, more subtle modifications should do it as well.