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UM2 "socks" - well it turned out to look more like spandex

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Posted (edited) · UM2 "socks" - well it turned out to look more like spandex

It appears that your mould has vertical side walls? To make removal of the casts easier, I would recommend that you use slanted walls where possible, if the model and its function allow it. For injection moulding a few degrees would do, but for 3d-printing (with rougher side walls) I would recommend more, maybe 10° or so.

Also, it may be a good idea to design a few holes or extensions in the outsides of your mould, or to make screw threads on places that will not be filled with the casting material, so that you can get a good grip with pliers, hooks, screws, or whatever tools, to get both mould parts apart after casting.

If your silicone auto-cures in a few weeks after opening, it probably is industrial or sanitary one-component silicone? This cures due to the moisture in the air. If you want longer shelf-life, try using real two-component mould-making silicone. There are a lot of good instruction videos on Youtube. Search for: "silicone mould making and casting".

Anyway, I really like this idea of silicone covers: it may not only keep the nozzle clean(er), but also prevent silicone from getting in-between the cooling plates in case of failed prints.

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Posted (edited) · UM2 "socks" - well it turned out to look more like spandex

Really like these covers. That's how they look like after +100 hrs of printing.

Never witnessed any curled up filament sticking to the nozzle.

nozzle-cover-3.thumb.jpg.dce06ce3e7f732a6b9bd133b37e67825.jpg

nozzle-cover-3.thumb.jpg.dce06ce3e7f732a6b9bd133b37e67825.jpg

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Posted · UM2 "socks" - well it turned out to look more like spandex

Nice. This would be really great.

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Posted · UM2 "socks" - well it turned out to look more like spandex

I've been playing around with a similar idea to insulate a custom fan duct (PLA) from the heater block. High-temp silicone (the red stuff) is needed to withstand the heat. Normal silicone is good for about 205°C continuous, whereas the high-temp silicone will withstand 300°C+.

In the US, I can find the high-temp one-part silicone in a tube for 5USD. I did not do a lot of searching but I haven't seen high-temp 2-part silicone that is readily available (and that cheap). That seems like it would be easier to use.

neotko, did you look in an auto parts store for high-temp (red) silicone? Permatex is a common brand in the US, although I'm using J-B Weld brand.

Permatex 81160 High-Temp Silicone Gasket Sealant

J-B Weld Hi-Temp Red Silicone

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Posted (edited) · UM2 "socks" - well it turned out to look more like spandex

I'm using Mold Max 60, a two compound hightemp silicon 294C

So far the nozzle molds went ok, but I did wrong the mix ratio and it took 48h to cure.

Also indeed the mold design needs adjustments to make it easier.

I'm in between 3 proyects so I'm going slow, finishing other stuff that I need more.

Also this two compounds (specially B blue) it's really abrasive and left the tip of a finger with a numb sensation for a full day, and the A stuff I don't know how breaks my gloves. So I need to get new, much better, gloves to handly this sticky red stuff.

Also I was wrong this stuff will last much more than a week when open, but since I never used this stuff I didn't knew.

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Posted · UM2 "socks" - well it turned out to look more like spandex

I found the Mold Max 60 last night as well. It seems like a good choice except the cost is above my (cheap) budget. If my experiments with the one-part silicone don't work, I may invest in some Mold Max 60.

The biggest problem I've encountered with the one-part RTV silicone that comes in a tube is that it takes forever to cure, and may never fully cure in the thick sections. It's also very viscous so it's difficult to get it to fill the mold.

I've read that it's possible to thin the silicone with xylene or charcoal lighter fluid. I've also read that you can improve curing by adding some glycerine or acrylic paint to the silicone, which adds moisture to initiate curing. Some experimentation is in order since I have lighter fluid and acrylic paint lying around the house.

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Posted · UM2 "socks" - well it turned out to look more like spandex

Rowiak,

I had great success with high temp automotive silicone See the boot I printed on the previous page. This was made with a reusable 3 piece mold from printed PLA. Corn flour (I finely ground corn meal in my coffee grinder instead) was added to help the silicon cure in hours. The mix was then injected into the oiled mold. Cured in a couple hours. Has served for years. I dont understand the chemistry, but the corn flour somehow alters the moisture in the RTV causing it to cure fast. No expensive silicone compounds required.

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Posted · UM2 "socks" - well it turned out to look more like spandex

mastory,

That's great, I'll try the corn flour. How did you deal with the thick consistency of the automotive silicone? Did you just use a syringe with a large piece of tubing to inject it? I think I could get it to flow through a 2 mm tube without too much trouble.

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Posted · UM2 "socks" - well it turned out to look more like spandex

mastory,

That's great, I'll try the corn flour.  How did you deal with the thick consistency of the automotive silicone?  Did you just use a syringe with a large piece of tubing to inject it?  I think I could get it to flow through a 2 mm tube without too much trouble.

 

The thickness wasn't an issue for me. My syringe is sort of large, maybe 50cc or more. I think the tip is maybe 3mm inside. I think I mis-spoke on the previous page - you need corn meal/flour, not corn starch to mix with the rtv. There was some discussion on this in another thread - https://ultimaker.com/en/community/3839-the-physics-of-cooling?page=3

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Posted (edited) · UM2 "socks" - well it turned out to look more like spandex

I just realised there may be an easier and faster way to create such covers. At least for some printer models.

In short:

- Find an undeep spoon, or something with a round hollow inside (e.g. cut off a part of a ping-pong ball).

- Fill that cavity with non-stick silicone paste.

- Heat up the nozzle a bit, e.g. to 100°C to speed up curing.

- Push the spoon up against the nozzle.

- Let the silicone cure.

- Remove spoon, remove flashes.

- And ready: you now have a silicone nozzle tip cover that is flush with the nozzle.

Notes:

- Only use non-stick, two-component mould making or artistic silicone, platinum cured (="additive"). Do not use tin cured silicones, as they are not form stable and not chemically stable, they may decompose. Do not use sticky sanitary or building silicone either, as they cure slowly (require moisture of the air), and you may have a hell of a time removing it afterwards.

- Be sure that the nozzle tip is completely filled with filament, so the silicone can not enter into the nozzle. It will not stick, but may still be difficult to get out.

- Use silicone paste, no liquid (it will leak away everywhere). Or if you only have liquid, after mixing let it cure until it is a paste, before applying.

- The spoon must be slightly undeeper than the length of the nozzle that is sticking out below the aluminum fan mount (on an Ultimaker 2, I don't know how it looks on other printers).

- Push the spoon firmly up against the nozzle, so the silicone will be flush with the nozzle tip.

Also have a look at the picture. This is based on an Ultimaker2, but the basic concept should also work for other printer heads.

The advantage is that you don't have to measure up your nozzle and you don't have to design any custom moulds anymore.

I haven't tried it myself yet, but I have used enough silicones to believe that it should work.  :-)

silicone_cover_nozzle_tip.thumb.jpg.1a380827549eab1d63c6e7221f675d70.jpg

silicone_cover_nozzle_tip.thumb.jpg.1a380827549eab1d63c6e7221f675d70.jpg

Edited by Guest
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Posted · UM2 "socks" - well it turned out to look more like spandex

That's a really cool idea!

 

Yep, but looking at the picture... is it removable (if i want to change the nozzle)?

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Posted · UM2 "socks" - well it turned out to look more like spandex

Maybe, if you get the amount of silicone right after several trials.

This idea is more an option for tinkerers who like to play around with silicone. But I like its simplicity.

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Posted · UM2 "socks" - well it turned out to look more like spandex

 

That's a really cool idea!

 

Yep, but looking at the picture... is it removable (if i want to change the nozzle)?

 

On a standard Ultimaker2, if you remove the aluminum plate with the fans, the silicone just slides off the nozzle. That is why you need to use non-stick silicone as used for mould making and casting. So it works just like removing a cast from a mould. Once the nozzle is out, you could force the rest out of the aluminum plate, if necessary.

Or you could just break the silicone piece, or cut it off, and apply fresh silicone. This sort of silicone is not that strong and tears apart easily.

Note that some molten filament may still creep under the silicone around the nozzle. That will depend on the hardness of the silicone, and on the liquid filament: whether it is repelled by the silicone or not.

For example water is strongly repelled by silicone. So any silicone tubing is absolutely water-tight. However, most oils are not repelled, and they slowly seep through silicone. Molten parafine (candle lights) also slowly seeps through silicone. Also solvents and vapours may seep through. That is why it is a good idea to use plenty of silicone oil on a fresh silicone mould, prior to using it for casting: the silicone oil will saturate the silicone mould, so the vapours and liquids of the casting plastic will not get into it so easily. This will prolong mould life.

So I could imagine that vapours or liquid plastic of filament might also to some degree seep into (or under) such a silicone cover. This will just be a question of trial and error. But for those cases where filament build-up around the nozzle is a real problem, it might be worth trying.

Also check if your silicone is heat resistant enough: most go to about 250°C, some lower, some higher. Some people even use them for casting lead and tin figurines.

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Posted (edited) · UM2 "socks" - well it turned out to look more like spandex

If filament building up and sticking to the nozzle is an issue, why not just wipe the nozzle with silicone lube before printing?  

That gets the non-stick all the way up to the rim of the nozzle, and should work even better than silicone rubber.

(It works nicely, BTW - it's part of my pre-print warmup routine now.)

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Posted · UM2 "socks" - well it turned out to look more like spandex

If filament building up and sticking to the nozzle isa an issue, why not just wipe the nozzle with silicone lube before printing?  

That gets the non-stick all the way up to the rim of the nozzle, and should work even better than silicone rubber.

(It works nicely, BTW - it's part of my pre-print warmup routine now.)

 

Yes, this is even more simple, definitely worth trying. I just hadn't thought of it...

Why make things simple, if we can also make them complex? :)

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Posted · UM2 "socks" - well it turned out to look more like spandex

No matter how - don't be silly - keep your nozzle clean! :p

DSCN0764B.thumb.JPG.af45e8f02a77bb07f79a080c4660efc0.JPG

I'm testing this for a week now (approx. 20-30 printing hours in summary) - it just works!

@foehnsturm: Thumbs up! 37_EmoticonsHDcom.png

DSCN0764B.thumb.JPG.af45e8f02a77bb07f79a080c4660efc0.JPG

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Posted · UM2 "socks" - well it turned out to look more like spandex

If filament building up and sticking to the nozzle is an issue, why not just wipe the nozzle with silicone lube before printing?  

That gets the non-stick all the way up to the rim of the nozzle, and should work even better than silicone rubber.

(It works nicely, BTW - it's part of my pre-print warmup routine now.)

 

I have tried it a couple of times now: I sprayed silicone oil on a tissue and wiped the nozzle with it, prior to starting each print.

Results: on the white PLA filament there is still a little bit of build-up of molten filament on the nozzle, but less than before. And it is way easier to remove afterwards than before. On the orange PLA filament there is none. (Both filaments: ICE brand.)

Further, the extruded sausages do no longer curl up and stick to the nozzle when starting a print: an unexpected result, but of course good.

So it is definitely worth trying. I think I am gonna make it a standard of my preparation too. Thanks for that tip.

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Posted · UM2 "socks" - well it turned out to look more like spandex

You're welcome - it only occurred to me as a result of reading this discussion.

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Posted · UM2 "socks" - well it turned out to look more like spandex

silicone_cover_nozzle_tip.thumb.jpg.1a380827549eab1d63c6e7221f675d70.jpg

 

I tried this today, but it did not work well. What I feared did happen indeed: molten filament creeps up between the nozzle and silicone cover, and it breaks the silicone at the top (where the nozzle meets the aluminum fan mounts) and pours out there in a big blob.

This is probably due to the silicone cover being flush with the nozzle, so it sort of pushes a bit on the surface while printing. When there is a little bit of overextrusion, as on the first layer or on short strokes with frequent stops, the melt choses the way of the least resistance, which seems to be in-between the nozzle and silicone cover...

It looked beautiful but didn't work, so I took it apart again. (I Forgot to take photos.) And I will stick to wiping the nozzle with silicone oil prior to printing.

silicone_cover_nozzle_tip.thumb.jpg.1a380827549eab1d63c6e7221f675d70.jpg

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Posted · UM2 "socks" - well it turned out to look more like spandex

Hi Foehnstorm,

these nozzel covers are verry exciting.

Can i buy one from you?

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Posted · UM2 "socks" - well it turned out to look more like spandex

Looks cool, perhaps this can be developed into a coating for the actual um parts from um3+ onwards!

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Posted · UM2 "socks" - well it turned out to look more like spandex

As E3D already produce a sock for their V6 a a very reasonable price, and have therefore done all the reasearch and development do you think they would produce them to suit the Olsson block and the matchless block as well?

There's enough of us using them to probably make it viable for them to do it commercially.

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Posted · UM2 "socks" - well it turned out to look more like spandex

foehnsturm and tinkergnome

is the red silicone material I see just thin silicone sheet you punched a hole in for the nozzle and then attached it to the bottom?

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Posted · UM2 "socks" - well it turned out to look more like spandex

Just for the heck of it, I decided to order some E3D silicone socks to see if I could make them work with my fan mount. Coincidentally, they fit perfectly into the nozzle hole in my design. The only thing I needed to do was cut off the the tabs sticking up from the back of the sock (see photo), because the Olsson block is longer. Other than that, it fits right in, and the fan mount holds it in place. With the sock installed, I can run my fans as high as I want without worrying about air being deflected back up into the heater block which can cause inconsistent layers. Unfortunately, this addition defeats the quick nozzle change feature of the original fan mount design.

fan_mount_sock.thumb.jpg.09d9c46f28005219c9e19c2033029f6b.jpg

sock.thumb.jpg.a284ec8a78e2d10ab6160b8683b85d74.jpg

fan_mount_sock.thumb.jpg.09d9c46f28005219c9e19c2033029f6b.jpg

sock.thumb.jpg.a284ec8a78e2d10ab6160b8683b85d74.jpg

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