Silicon boot for hot block.

[JF Kansas]

So it seems a thermal boot for hot blocks are the "in" thing. So for my hot block I designed a custom boot that would need to be injection molded with some sort of high temp silicon.

Thinking about printing a 2 piece mold to make these. The Silicon takes a couple hours to cure so hopefully can do 6-8 at a time. So a lot of the silicons out there are for making molds to cast other things, not really for an end use product. Anything out there specifically for this and is good for around 300c? 

[Brandon A.]

I doubt they would tell you but the silicone encased Rep2X replacement hot block from Fargo 3D has 3DP lines so I assume it wasn't made the fancy way.  PM Jake Clark (active on Makerbot UsersGG), it can't hurt to ask.  

[Wing Wong]

A lower tech approach would be to buy a roll a self-sealing high temp silicone tape. You'd need to re-wrap it each time you had to take the head assembly apart, but then again, it's generally $4-$5 for a silicone boot/sock. For a 10' roll of 1" wide high temp silicone self-sealing tape, it's $10-$25 depending on brand/quality/quantity... but it would take about what? 6" of tape to do the job? So each roll has about 20 uses and would conform to any shaped head. 

Something like:

https://smile.amazon.com/Soledi-Waterproof-Silicone-Repair-Bonding/dp/B01J9D33AM

A molded silicone piece would be cool, but just looking at my own hot end collection, a silicone tape route would be more practical. If I had a whole bunch or wanted to sell, then definitely, go with a cast/mold route.

Looks like you can get 100% silicone caulking, but unsure as to the temp ratings for them. Some of the fireplace/fire-proof high temp sealant can withstand higher temps, but they note that they can expand. 

W.

Wing Wong
winge...@gmail.com
http://about.me/wingtangwong

https://www.facebook.com/wingedpower

--
You received this message because you are subscribed to the Google Groups "3DP Ideas" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+unsubscribe@googlegroups.com.
To post to this group, send email to 3dp-...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/c907bf98-be52-486b-9d1d-deb33dc6b14d%40googlegroups.com.

For more options, visit https://groups.google.com/d/optout.

[JF Kansas]

This is for a hot block that I produce and sell so kinda looking for a little more convenient solution for the end user.

I just did a quick search last night for the products to do this and finished the design. This is my first go at a mold so it will be a learning experience. It is rubber that stretches, and that helps, but still have to design the mold so the product will have a way to come out. This will be tricky with the holes in the cover, but I think I know how to make it work. Just not sure if a 3d printed mold will be up to the task, and I need multiple molding cavities so I can to a bunch at a time. The more I think about this it is no wonder mold making is so expensive. There is more to it than I realized. 

Was thinking a RTV High temp product would be up to the task to inject into the mold cavity. 

On Tuesday, September 20, 2016 at 12:02:07 PM UTC-5, Wing Wong wrote:

A lower tech approach would be to buy a roll a self-sealing high temp silicone tape. You'd need to re-wrap it each time you had to take the head assembly apart, but then again, it's generally $4-$5 for a silicone boot/sock. For a 10' roll of 1" wide high temp silicone self-sealing tape, it's $10-$25 depending on brand/quality/quantity... but it would take about what? 6" of tape to do the job? So each roll has about 20 uses and would conform to any shaped head. 

Something like:

https://smile.amazon.com/Soledi-Waterproof-Silicone-Repair-Bonding/dp/B01J9D33AM

A molded silicone piece would be cool, but just looking at my own hot end collection, a silicone tape route would be more practical. If I had a whole bunch or wanted to sell, then definitely, go with a cast/mold route.

Looks like you can get 100% silicone caulking, but unsure as to the temp ratings for them. Some of the fireplace/fire-proof high temp sealant can withstand higher temps, but they note that they can expand. 

W.

Wing Wong
winge...@gmail.com
http://about.me/wingtangwong

https://www.facebook.com/wingedpower

On Tue, Sep 20, 2016 at 9:23 AM, Brandon A. <andoj...@gmail.com> wrote:

I doubt they would tell you but the silicone encased Rep2X replacement hot block from Fargo 3D has 3DP lines so I assume it wasn't made the fancy way.  PM Jake Clark (active on Makerbot UsersGG), it can't hurt to ask.  

On Tuesday, September 20, 2016 at 8:00:27 AM UTC-5, JF Kansas wrote:

So it seems a thermal boot for hot blocks are the "in" thing. So for my hot block I designed a custom boot that would need to be injection molded with some sort of high temp silicon.

Thinking about printing a 2 piece mold to make these. The Silicon takes a couple hours to cure so hopefully can do 6-8 at a time. So a lot of the silicons out there are for making molds to cast other things, not really for an end use product. Anything out there specifically for this and is good for around 300c? 

--
You received this message because you are subscribed to the Google Groups "3DP Ideas" group.

To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+...@googlegroups.com.

To post to this group, send email to 3dp-...@googlegroups.com.

[JF Kansas]

Thanks, Ya there is proto labs and another place I found. I just don't do the quantities needed to justify a $2000 mold. But it isn't totally out of the question. And like what has been talked about recently, a cover really isn't that needed for the hot end so was just seeing if I could do some economically. 

[Whosawhatsis]

The Bukito hot ends are wrapped in the self-sealing silicone tape. You need to avoid putting it under much tension because it will crack when it gets hot. It holds up pretty well at PLA temperatures, but mine has completely disintegrated because I've printed PC on that machine. If you're printing a lot of ABS/PETG/Nylon, that will break it down more slowly.

To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+...@googlegroups.com.

To post to this group, send email to 3dp-...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/CAM0i%2ByrzcZOD8rnTrehvQF9RYNqK46Bjrhrf9XBv_woPc3VNEQ%40mail.gmail.com.

[Wing Wong]

Thanks WW, that is very good to know!

W

To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+...@googlegroups.com.
To post to this group, send email to 3dp-...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/c907bf98-be52-486b-9d1d-deb33dc6b14d%40googlegroups.com.

For more options, visit https://groups.google.com/d/optout.

--
You received this message because you are subscribed to the Google Groups "3DP Ideas" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+...@googlegroups.com.
To post to this group, send email to 3dp-...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/CAM0i%2ByrzcZOD8rnTrehvQF9RYNqK46Bjrhrf9XBv_woPc3VNEQ%40mail.gmail.com.

For more options, visit https://groups.google.com/d/optout.

--
You received this message because you are subscribed to the Google Groups "3DP Ideas" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+...@googlegroups.com.
To post to this group, send email to 3dp-...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/CAO3p9u3T9m39iezYB1TkqyZfp14DboRrqDLbCbFgmuKDFKoTjQ%40mail.gmail.com.

[Bob Bilbrey]

You don't need to injection or transfer mold.  You can 3dprint multi cavity molds and pour the boots.  I've made silicone parts in the past and it is quite easy.  The key is to have the silicone-hardener mix bubble free before pouring and to avoid air entrapment when you introduce the mix into the mold.  I used a simple bell-jar hooked to a water powered aspirator which pulls a very good vacuum.  There are many youtube videos describing de-bubbling methods.  It is also simple to design and print a 3Dprint two part mold array providing you have some understanding of molding/casting processes.   Nice little project.  

              This link is for 300C silicone 

https://www.amazon.com/Mold-High-Resistant-Silicone-Rubber/dp/B00IZNNIU8/ref=sr_1_14?ie=UTF8&qid=1470156074&sr=8-14&keywords=silicone+rubber+casting

[Jelle]

tried to make a silicone boot with bathroom silione + sodium bicarbonate (to make it foam). It still went brown pretty quick, but the foam might be a good idea: It may keep the material cooler on the inside.

But I suspect that the silicone boot is trying to do two things: keeping the block insulated/hot and keeping the nozzle + block clean. Heat insulation is imho much better done with that felt + tape thingy you can buy for allmost nothing from ali, or in a pinch a few folds of aluminium foil wrapped around the block. The other feature is keeping the nozzle clean, that is where I think should be the focus on, as that can have a direct influence on the quality of the print.  So perhaps have the silicone boot only cover the nozzle (with a hole for the tip) and clamp that to the heater block with a (felt insulated) heat shield.

Don't know if that can compete with the one part silicone boots though?

To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+unsubscribe@googlegroups.com.

To post to this group, send email to 3dp-...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/c907bf98-be52-486b-9d1d-deb33dc6b14d%40googlegroups.com.

For more options, visit https://groups.google.com/d/optout.

--
You received this message because you are subscribed to the Google Groups "3DP Ideas" group.

To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+unsubscribe@googlegroups.com.

To post to this group, send email to 3dp-...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/CAM0i%2ByrzcZOD8rnTrehvQF9RYNqK46Bjrhrf9XBv_woPc3VNEQ%40mail.gmail.com.

For more options, visit https://groups.google.com/d/optout.

--
You received this message because you are subscribed to the Google Groups "3DP Ideas" group.

To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+unsubscribe@googlegroups.com.

To post to this group, send email to 3dp-...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/CAO3p9u3T9m39iezYB1TkqyZfp14DboRrqDLbCbFgmuKDFKoTjQ%40mail.gmail.com.
For more options, visit https://groups.google.com/d/optout.

--

You received this message because you are subscribed to the Google Groups "3DP Ideas" group.

To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+unsubscribe@googlegroups.com.

To post to this group, send email to 3dp-...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/CAM0i%2ByofDFS5guBWFq2-hiDeNc0u5P2wO0BwRmSyDFgP9QrLQw%40mail.gmail.com.

For more options, visit https://groups.google.com/d/optout.

--

met vriendelijke groeten,
Jelle Boomstra

[JF Kansas]

Thanks, ya that smooth on stuff is one that I was looking at. Here is where I am at so far on an 8 up mold. Each rubber is a little under 3cc of volume so I hope to be able to fill each cavity with 3cc of rubber liquid then let the rest ooze out in the vents. Have to order up some silicon and see how it works. 

[Whosawhatsis]

You might want to add some alignment pieces to ensure that they go together straight (rather than relying on the hole cutouts for that). You also might want to add some holes to give the overflow somewhere to go. Maybe even make the top piece a frame that loosely holds the pieces together rather than a solid plate.

From: JF Kansas <jfka...@gmail.com>
Reply: JF Kansas <jfka...@gmail.com>
Date: September 22, 2016 at 01:45:50
To: 3DP Ideas <3dp-...@googlegroups.com>
Subject:  [3dp-ideas] Re: Silicon boot for hot block.

Thanks, ya that smooth on stuff is one that I was looking at. Here is where I am at so far on an 8 up mold. 

On Wednesday, September 21, 2016 at 7:26:05 PM UTC-5, Bob Bilbrey wrote:

You don't need to injection or transfer mold.  You can 3dprint multi cavity molds and pour the boots.  I've made silicone parts in the past and it is quite easy.  The key is to have the silicone-hardener mix bubble free before pouring and to avoid air entrapment when you introduce the mix into the mold.  I used a simple bell-jar hooked to a water powered aspirator which pulls a very good vacuum.  There are many youtube videos describing de-bubbling methods.  It is also simple to design and print a 3Dprint two part mold array providing you have some understanding of molding/casting processes.   Nice little project.  

              This link is for 300C silicone 

https://www.amazon.com/Mold-High-Resistant-Silicone-Rubber/dp/B00IZNNIU8/ref=sr_1_14?ie=UTF8&qid=1470156074&sr=8-14&keywords=silicone+rubber+casting

On Tuesday, September 20, 2016 at 6:00:27 AM UTC-7, JF Kansas wrote:

So it seems a thermal boot for hot blocks are the "in" thing. So for my hot block I designed a custom boot that would need to be injection molded with some sort of high temp silicon.

Thinking about printing a 2 piece mold to make these. The Silicon takes a couple hours to cure so hopefully can do 6-8 at a time. So a lot of the silicons out there are for making molds to cast other things, not really for an end use product. Anything out there specifically for this and is good for around 300c? 

--
You received this message because you are subscribed to the Google Groups "3DP Ideas" group.

To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+...@googlegroups.com.

To post to this group, send email to 3dp-...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/188fa9fe-b1fa-488c-a384-3328d1a3d376%40googlegroups.com.

[JF Kansas]

Yep on alignment, just haven't added things. Was thinking about putting 15 bolts in the corners to clamp it, or may just put pins and toss a big piece of granite on top. The overflow "viens" are there, may be hard to see. 

[Ryan Carlyle]

Does this silicone warm up as it cures like PU does?

[JF Kansas]

https://www.smooth-on.com/tb/files/MOLD_MAX_60_TB.PDF

Here is the data on it. It mentions an alcohol/water condensation reaction so I imagine that creates a little heat. 

[Ryan Carlyle]

You know what would be fun? Building a 3D printed pump to inject the silicone into the mold. Manual pouring is for weenies :-)

[JF Kansas]

This stuff is pretty thick, like 20000cps, so going through a pump might not be too smooth. But guess depends on the pump, then there's the pump cleaning :-(   I will probably use an accelerator that makes the set up time go from 24 hours to 2 hours or so. That means the working time is shortened considerably. 

[Ryan Carlyle]

Oh, I've got pump tricks for viscous fluids. That's why it's fun :-)

Probably use a special type of viscoelastic-fluid disc pump (3D printed and disposable but you'd probably coat it with mold-release) for an initial suction boost stage, and then a peristaltic pump with some cheap tubing for the main metering/pressure stage. Throw away the tubing after every use.

[JF Kansas]

Ya, maybe in future. Probably will try drawing into a syringe or just pouring a little in.

[Whosawhatsis]

What would be impressive is if you have a way to remove any air bubbles from the stuff as it's being pumped. For silicone, the most common way I've seen to do this is to pour it in a thin stream from high above the mold so that most of the bubbles will pop on the way down (sometimes called the "bombs away" method).

From: Ryan Carlyle <temp...@gmail.com>
Reply: Ryan Carlyle <temp...@gmail.com>
Date: September 22, 2016 at 14:15:10
To: 3DP Ideas <3dp-...@googlegroups.com>
Subject:  [3dp-ideas] Re: Silicon boot for hot block.

--
You received this message because you are subscribed to the Google Groups "3DP Ideas" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+...@googlegroups.com.
To post to this group, send email to 3dp-...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/531a9886-f700-4bcc-98eb-c0f35b146e35%40googlegroups.com.

[Ryan Carlyle]

Short of an intermediate vacuum degasser stage, no, I don't have any good ideas for that. I'm not aware of any other good ways to get bubbles out of high-viscosity fluids aside from vacuum and centrifuging. The suction pump I'm thinking of might de-gas, or it might shear them out to lots of smaller bubbles, I'm not sure. 

Looks to me like you can get a vacuum chamber and vacuum pump for $100 on Amazon. Add a little for tubing and fittings and you should be good. 

On Thursday, September 22, 2016 at 6:02:45 PM UTC-5, Whosa whatsis wrote:

What would be impressive is if you have a way to remove any air bubbles from the stuff as it's being pumped. For silicone, the most common way I've seen to do this is to pour it in a thin stream from high above the mold so that most of the bubbles will pop on the way down (sometimes called the "bombs away" method).

From: Ryan Carlyle <temp...@gmail.com>
Reply: Ryan Carlyle <temp...@gmail.com>
Date: September 22, 2016 at 14:15:10
To: 3DP Ideas <3dp-...@googlegroups.com>
Subject:  [3dp-ideas] Re: Silicon boot for hot block.

Oh, I've got pump tricks for viscous fluids. That's why it's fun :-)

Probably use a special type of viscoelastic-fluid disc pump (3D printed and disposable but you'd probably coat it with mold-release) for an initial suction boost stage, and then a peristaltic pump with some cheap tubing for the main metering/pressure stage. Throw away the tubing after every use.

--
You received this message because you are subscribed to the Google Groups "3DP Ideas" group.

To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+unsubscribe@googlegroups.com.

[Ryan Carlyle]

Actually, centrifuging isn't THAT bad of an idea. I bet you could make a spin-fill casting rigup. Put the uncured mix in a central bucket, and spin it into the molds. http://www.thingiverse.com/thing:1483

[JF Kansas]

I'm thinking for the purpose of these that a few small bubbles aren't going to matter a lot. Also as the mold is assembled a lot of bubbles will pop due to the two halves compressing the liquid into a 2mm gap. Maybe not, just gotta test it out and see what happens. 

On Thursday, September 22, 2016 at 6:48:20 PM UTC-5, Ryan Carlyle wrote:

Actually, centrifuging isn't THAT bad of an idea. I bet you could make a spin-fill casting rigup. Put the uncured mix in a central bucket, and spin it into the molds. http://www.thingiverse.com/thing:1483

On Thursday, September 22, 2016 at 6:42:32 PM UTC-5, Ryan Carlyle wrote:

Short of an intermediate vacuum degasser stage, no, I don't have any good ideas for that. I'm not aware of any other good ways to get bubbles out of high-viscosity fluids aside from vacuum and centrifuging. The suction pump I'm thinking of might de-gas, or it might shear them out to lots of smaller bubbles, I'm not sure. 

Looks to me like you can get a vacuum chamber and vacuum pump for $100 on Amazon. Add a little for tubing and fittings and you should be good. 

On Thursday, September 22, 2016 at 6:02:45 PM UTC-5, Whosa whatsis wrote:

What would be impressive is if you have a way to remove any air bubbles from the stuff as it's being pumped. For silicone, the most common way I've seen to do this is to pour it in a thin stream from high above the mold so that most of the bubbles will pop on the way down (sometimes called the "bombs away" method).

From: Ryan Carlyle <tem...@gmail.com>
Reply: Ryan Carlyle <tem...@gmail.com>
Date: September 22, 2016 at 14:15:10
To: 3DP Ideas <3dp-...@googlegroups.com>
Subject:  [3dp-ideas] Re: Silicon boot for hot block.

Oh, I've got pump tricks for viscous fluids. That's why it's fun :-)

Probably use a special type of viscoelastic-fluid disc pump (3D printed and disposable but you'd probably coat it with mold-release) for an initial suction boost stage, and then a peristaltic pump with some cheap tubing for the main metering/pressure stage. Throw away the tubing after every use.

--
You received this message because you are subscribed to the Google Groups "3DP Ideas" group.

To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+...@googlegroups.com.

[Whosawhatsis]

How is compression going to pop the bubbles if the air doesn't have anywhere to go?

From: JF Kansas <jfka...@gmail.com>
Reply: JF Kansas <jfka...@gmail.com>

To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/59727c29-0480-444b-8a93-7b3a90c1a4f9%40googlegroups.com.

[JF Kansas]

It can go up and vent out the sides. I'm gonna try to not have any air at all. 

On Thursday, September 22, 2016 at 8:34:20 PM UTC-5, Whosa whatsis wrote:

How is compression going to pop the bubbles if the air doesn't have anywhere to go?

From: JF Kansas <jfk...@gmail.com>
Reply: JF Kansas <jfk...@gmail.com>

[Whosawhatsis]

If the air was going to bubble out, it would do that in the first place. The silicone is too viscous and the buoyancy isn't sufficient.

From: JF Kansas <jfka...@gmail.com>
Reply: JF Kansas <jfka...@gmail.com>

To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/239d8018-d18b-4f05-8185-539c70e187f7%40googlegroups.com.

[JF Kansas]

When the top is put on it will displace the rubber and push most of the material out and up. Hopefully will get most of it. Will focus on not getting air in the mix in the first place and should be pretty good for the function of the boot. 

Will see what happens, gonna be a week or so until the product gets here. Gives me time to print and clean up the molds. 

On Thursday, September 22, 2016 at 10:53:13 PM UTC-5, Whosa whatsis wrote:

If the air was going to bubble out, it would do that in the first place. The silicone is too viscous and the buoyancy isn't sufficient.

[Wing Wong]

@JF, just saw this on my G+ stream:

https://plus.google.com/+LukasMathis/posts/Bie576tm6ZG

Basically, the bottom of the E3D silicone boot ended up getting caught on some printed PLA plastic and tugged it down just enough so that the extruded plastic started to fill the boot instead of being laid down. 

Some talk about securing the boot in some way to prevent it. Thought it would be a good data point since you were working on a cover as well. 

W.

Wing Wong
winge...@gmail.com
http://about.me/wingtangwong

https://www.facebook.com/wingedpower

To unsubscribe from this group and stop receiving emails from it, send an email to 3dp-ideas+unsubscribe@googlegroups.com.

To post to this group, send email to 3dp-...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/3dp-ideas/30c087da-f66a-4eae-a2f9-e3335ed5858f%40googlegroups.com.

[JF Kansas]

Ah wow, that's a mess. Mine is designed quite a bit different and should fit more snug. It looks like the E3d one needed a couple wraps of kapton tape to help hold it on.

I ordered the silicon the other day, should have it this week. Printing out the molds this weekend. 

[tray]

Hmm, maybe cast in air channels for your cooling fan?

[JF Kansas]

What do you mean cooling fan?

[JF Kansas]

Silicon material got here yesterday. Mold production underway. Decided to go with a 4 up mold to start with. Faster to print, and less waste if something doesn't work right. 

Now to figure out how to mix up the stuff. The 100parts of A and 3 parts of B is easy. But have some Accelerator that needs to be mixed at .2% of the volume of part B. Seems like that would be just a few drops of it. 

I need about 12ml of sliicon to make 4 covers. Nice of them to have some handy calculators.

So. .52g of part B and I need .2% of that for the Accelerator. 

That is .001 grams. lol  How the heck do you measure out .001 grams?

[Ryan Carlyle]

Heh. Good luck with that :-)

Only thing I can think of is to dip the slightest bit of the tip of your stirring device into the accelerant, and hope it works out. 

[JF Kansas]

Ya might have to cause this stuff is really sensitive to that accelerator. Normal pot time without is 40 minutes. With .2% added to Part B is 24 minutes, and 1% added is 3 minutes. 1% would be .005 grams and one drop of water is like .05 grams. lol

[Timothy Zalusky]

Keep me posted on how it goes!

With any luck, I might be able to test some of them :D

Might be a while until my new machine is up though... Ordering everything has taken longer than I thought

[JF Kansas]

Batted almost 50% on the new mold. Think I am going to forget the accelerator and just let it slow cure. 

[Brandon A.]

Looks good from arms length across the internet!  Sounds like you are happy with the results (at least half).  What was the difference between the good and bad?

Be sure to toss a couple random characters after your images to keep Google from quote hiding them.

[JF Kansas]

The bad ones didn't set up in places so I must have not got the stuff fully mixed. I think it was the accelerator because it started to clump almost instantly. I tried to mix it out but don't think I got it all distributed. The problem is the accelerator is literally a half drop with the quantity I am mixing. Then Part B is .4ml. which isn't much either, so it was impossible to mix a half drop of accelerator into .4ml of Part B. Then I added Part B to A, and it sat there for a little bit before I started mixing so i think the clump was from where the part B sat in the part A too long. On the outside of the mold sat a little material that squeezed out and it was still "wet" and so was the inside of the little mixing cup. I was expecting the worst when taking the mold apart thinking that nothing would be set up and I would be spending a day trying to clean out the mold cavities. Good thing except for a couple little wet spots in the mold, they are essentially ready to go again.   

I really think I need to have 4 molds ready so I can mix up enough for 16 at a time. It should be easier to mix out the Part A and Part B with the larger quantities. The ratio is 100A:3B by weight. I don't have a scale to measure out the .5 gram of Part B so I ended up figuring about how many ml or units it was for .5 grams. 

The only scale I have is a postal scale and it does 1g increments. But I have a better one on order.

[Ryan Carlyle]

Alternative option, come up with something else fun to do with silicone, and mix up a bigger batch to include the other thing. How expensive is this stuff, anyway?

[JF Kansas]

The minimum amount was $50 bucks or so shipped. That didn't include the $10 accelerator, so total order was like 62 shipped. Total amount is 1pt or so. The can they ship is about half full. 

I was actually thinking the same thing of doing something else with it but couldn't think of anything at the time. It would be fun to do some Tin casting which is what this stuff is made for. 

[JF Kansas]

I do need to work on degassing the stuff. Was thinking about rigging something up with one of these for that task.

https://www.amazon.com/gp/product/B00MV8R0IY/ref=ox_sc_sfl_title_65?ie=UTF8&smid=A3VZEZDUSWXB7M&th=1

[Brandon A.]

So glad that's now going to show up on my wife's Amazon recently viewed.  =P

I tend to mix more than I need to account for waste on the sides of the container mixed in.  This of course would be solved if I had a spatula at work, somehow I never remember to purchase one.

[JF Kansas]

Lol, we will call it a scientific instrument. 

Ya I had some extra mixed but not enough to do anything with. I was hoping to use the cup to tell when the silicon was cured, but the excess in the cup is still wet enough to get some on your finger. Really just need to mix things better I am sure, once it kind of clumped up I got in a hurry so I could get it in the mold.  

[Brandon A.]

I know that feeling.  I was used to a 10-30 min working time and the first time I used Repro-Rubber I didn't RTFM and ended up with a really nice casting of the 3mL syringe I was dispensing with. >.<

I have a love-hate relationship with that product, it's very good at what it does but it's expensive and cures so fast it gives me pouring/injecting anxiety every time.

New production methods are fun and all, but how do your boots perform on a printer?  Have any tests planned for it?

[Timothy Zalusky]

As far as testing, if he's able to make enough, I should be able to test them on my printers (FFCP, and corexy in the making).

Of course, that will be more qualitative than quantitative testing unless I actually take the time to see if it has an effect on power usage/temp stability.

[tray]

really more of a air flow splitter so you can blow cooling air at your print without blowing directly at the nozzle

[JF Kansas]

So on a chemistry standpoint, this is a 2 part mix. 100parts A to 3 parts B.  What would happen if I used 4 or 5 parts of B? Speed cure time or change the elasticity and/or shore of the rubber? 

On Tuesday, September 20, 2016 at 8:00:27 AM UTC-5, JF Kansas wrote:

So it seems a thermal boot for hot blocks are the "in" thing. So for my hot block I designed a custom boot that would need to be injection molded with some sort of high temp silicon.

Thinking about printing a 2 piece mold to make these. The Silicon takes a couple hours to cure so hopefully can do 6-8 at a time. So a lot of the silicons out there are for making molds to cast other things, not really for an end use product. Anything out there specifically for this and is good for around 300c? 

[Ryan Carlyle]

Ummm... good question. You'd basically end up with an excess of the curing agent as a contaminant in the final product. Probably some minor degradation of final material properties, maybe more post-cure out-gassing when the boots are heated. I don't know enough about the chemistry of your specific silicone to say much more than that. 

[JF Kansas]

I did a little research on this and found some info about there being a window of about 20% over by weight and it won't change much. Over that and the product can be come brittle and not as flexible. So it seems it affects shore and elasticity. Not sure about cure rates though. I'm not too worried about elasticity but would like to get faster cure times. That accelerator is way too aggressive. In the smallest amount I can deliver it is almost like an insta set. No time for degassing or anything. 

[JF Kansas]

Found this stuff the other day. I like it since it is black, the rust color of the Smooth on stuff is functional but kinda dull looking.

When I run short of the "red" stuff I will try this out. It has over 2x the heat resistance also. 

https://www.riogrande.com/Product/high-temperature-rtv-mold-compounds/701014