3D printed plastic burner experiments (photo heavy)

[Another FrankenBurner]

Thanks Frosty.  I can't prove most of that stuff so it is a mental work in progress. 

Velocity was one of those things which I couldn't quite wrap my head around for a while.  A hotter flame has a higher rate of combustion, it's burning faster.  More fuel per second.  Does FAM stream speed have anything to do with controlling temperature?  If the FAM stream is pushed to a higher velocity will burn hotter?  

A hotter flame will require a faster stream, because it's hungry, but that doesn't mean feeding it more will make it hotter.  Flame speed and temperature are proportional.  If you get the mix closer, it will burn faster.  Faster is hotter.  So long as the stream is faster than the flame, no suck back.  Increasing the FAM speed beyond this propagation velocity does nothing to the temperature.  It just makes the flame bigger.

Things are starting to make some sense over here.  Wait... does anyone else smell smoke?

Most late improvements have been in casting technique.  Though, we are playing around with zircon slip so hopefully material improvements are in the future.  Improvements were easier to come by in the beginning.  Now we are having to work for it.  We had a lot of failures for a while there but it's getting exciting again.

5 hours ago, SnowdragonIW said:

I am so happy right now! This was not to much information.

I got two of you to read the whole thing?  I'm glad any of that helped you and gave you more questions.  The more you learn, the less you'll know.  Questions are the best part of all of this.  Or was it playing with fire?

Don't think too hard on your build though.  Do a little research and then just build it.  Even if you build one that barely works, that still means you can hit metal while you over think the next one.  We have 4 forges in progress and 6 completed.  They are all different.  Every one of them has something wrong.  Every one of them works just fine. 

I know kast-o-lite has some kind of short fibers in it.  If you break pieces off, you can see the little hairs sticking out.  I have not played with adding things to the refractory. 

My first forge was a freon mini forge, built mostly to Ron Reil's website advice.  I did add a 1/4" of kast-o-lite.  I didn't really know what I was doing.  I probably added too much water when mixing.  I smeared it on, let it "dry" overnight, fired it up the next day.  I threw metal into the walls, I once had a piece heat up and expand to the point it trapped between the two sides, I had a lot of rain water make its way into it and I fired it up anyway(the burner was not happy), I broke the face off stabbing my work into it, I abused it in my learning.  She is still around.  A few cracks along the way and I redid the face when it broke.  Kast-o-lite is pretty tough stuff, sans flux.  Somewhere along the way, I learned to slow down.

I have not noticed issues with thick versus thin area cooling at different rates causing problems.  I've never even considered it. I think we are lucky to have access to a product which tolerates imperfect handling.  

Don't worry about the erroneous importing information stuff.  I like information, import away.  If it turns out to be irrelevant, the price was right.  I am not afraid of a little deep reading.  I got Frosty the reader to keep me company and teach me new words.

We just recently used the kiln to cure a liner and some nozzles according to refractory manufacturer recommendations.  Up until now, we used the burner gently to cook the refractory like everyone else.  This kiln cooked forge sounds like glass went flicked.  We haven't given it a good enough run yet to know if the kiln cookout is worth the power.

[Frosty]

Taking mental vacations with ideas and such is how I work things out before going to the drawing board. Thoughts are always popping up if one seems interesting we'll take a stroll and see where it leads. 

We're looking at the same thing differently. Velocity has a whole lot less to do with ambient flame temperature than it seems you may think. On the other hand the closer to a neutral burn the faster the rate of combustion/propagation so Yes a hotter flame is faster. That isn't necessarily the flame speed out of a burner though so it's sort of apples and oranges in a forge.

Assuming a neutral burn and say 3,000f flame doesn't say how hot the forge will be, can be yes. It comes down (in my mind) to how much FAM burns per second in the chamber. So, as you say a flame has to be fast enough to burn enough fuel in the chamber to overcome heat transfer through the liner and exhaust and IR leakage out the openings. Too fast though and the flame blows through the chamber and burns outside and wastes fuel and breathable. 

"A hotter flame will require a faster stream because it's hungry." HUH? A neutral flame will be X degrees regardless of how fast the stream is. It's easy to prevent a flame from burning back even if the flow is WAY below it's rate of propagation. There is a size limit through which a flame CAN pass. You've seen radiant propane heaters. Yes? Your statement is true if you substitute "forge" for "flame". And we get back to my viewpoint.

So, yes you can control the forge temperature by controlling stream velocity, either throttling it down and not burning as much in the chamber or speeding it up and blowing the heat through the forge. Option 2 is pretty silly when you think about it but look at the videos online, some forges are crazy wasteful of fuel and breathable air.

Being easy to throttle in use is one of my favorite things about NA burners.

And just because it's a fun thing to me, I'll be pleased to pop another intuitively logical mistake. Of course you can have a furnace temperature hotter than the flame. The mechanism is compression heating. By forcing a greater volume of flame into a chamber than the chamber's volume the flame MUST shed heat to the chamber walls. Touch your compressor tank some time. Compression heating is brownian movement that is forced to bounce between closer barriers. Bounce a ping pong ball on a table and shorten the space between table and paddle, it goes faster and faster and is an excellent model of brownian movement and compression heating. 

Hmmmm? 

Frosty The Lucky.

[ThomasPowers]

The "traditional" way to strengthen castable refractories by adding fibrous material was to use asbestos...NOT SUGGESTED!!!!!!!!!!!!!!!!!

[Another FrankenBurner]

Thanks for all that Frosty.  It helps the wheels turn.  I think we are on the same page, saying the same thing, but I stated it poorly.  I was picturing a single flame from a straight burner in open air, excluding the very cool quench diameter stuff and the forge side of things.

I was stating that stream velocity does not change flame temperature.  This was the thing I was mentally hung up on for a while.

I used the terms flame speed and propagation velocity to mean the same thing which is confusing.  From now on I will use flame speed to mean the speed of the flame out of the burner, and propagation velocity to mean the rate of combustion.  Apples and oranges as you said.  

"A hotter flame will require a faster stream because it's hungry."  I meant that at a given propagation velocity, there will be a minimum flame speed requirement.  Increase the propagation velocity and the minimum flame speed will also increase but increasing the flame speed beyond this minimum requirement will not increase propagation velocity(temperature).

When it comes to how this all operates with a forge, we are in agreement.  Too fast is wasteful.

8 hours ago, Frosty said:

And just because it's a fun thing to me, I'll be pleased to pop another intuitively logical mistake. 

This one made me laugh.  I am glad you were entertained.  If I am going to make a mistake, at least it's intuitively logical.  I'm wrong but I'm not stupid.  You are good with the words.  I enjoy our conversations.  

Compression heating, aren't you stretching a little on this one?  Do you think we could compress enough flame to overcome losses enough to raise the temperature of the forge above the temperature of the flame with a pipe burner?  

Joking aside, I would have never thought about compression in this application.  Are there furnaces which use this technology?  What kind of burner are they using?  I am imagining some form of supplied air, compressed or forced.

[Frosty]

Yes, we're talking about the same thing with different terms pretty much on the same page. No real disagreement.

Yes, compression heating is everywhere. It's a big reason ground temperatures run higher than ambient under an inversion layer. It can also make it warmer when a prevailing wind meets mountains or ridges. We use compression heating and the reverse every day to make refrigerators cold and heat pumps heat and cool our house. 

No, I don't know of furnaces making use of compression heating specifically but a law of thermodynamics applies regardless. There are some burners that use compression heating but to improve burner performance not in the furnace. We know it's easy to over heat the intake air in a recuperative forge but a number of burner designs heat the propane. The one we've all seen is the burners in hot air balloons, they're recuperative preheaters of course.

The compression pre heaters used pumps  at or near the jet nozzle. 

We live with and make use of compression heating every day.

Sure any increase in furnace temperature due to compression would be negligible with NA burners but yes it could be and maybe is significant enough to use with gun burners, especially in large commercial furnaces. Regardless compression heating exists and certainly COULD cause a furnace's temperature to exceed flame temperature. 

I only said it's possible as an invite to a little mental idea stroll. Of course I don't want to imply you're stupid, that'd make me dishonest. I really try not to be dishonest, mistaken(?) oh yes, all the time but not dishonest.

Sure I like to spread a little BS but that's for entertainment or as a teaching tool. I'd have to be an idiot to think you're stupid. I don't even have to look for ways to avoid that implication.

It's MUCH harder when you are discussing things with folk who are expounding way out of their depth, I think of them as products of the EDYtube system. That segment has been around longer than I have, I've even been a member when I was a kid. I remember kids expounding on "known facts" they got from a DC comic book. Bruce Wayne is a scientist you know! Nobody is immune to accepting wrong information but today we can look into things more easily thad going to a library. 

Frosty The Lucky.

[Another FrankenBurner]

Why is asbestos not suggested. That stuff is great.  From the fire fighter suits to the dining room table pads to the chair covers.  That way when Barney Rubble drops his Winston, he doesn't set the house on fire.  Of all the things I like bestest...

[Another FrankenBurner]

I did not take anything you said the wrong way Frosty.  I didn't think you were calling me stupid and I didn't take any offense, I never do.  I was mostly just joking around and complimenting your elegance with word selection.  I should probably watch my humor as written word is so easy to misinterpret.  I am a weird guy so my humor is off.  

I like being challenged when I am wrong especially when it contains reasoning.  I don't want to put out bad information which I why I often preface things with "as I know it currently."  None of my knowledge is concrete.  If I can test information, I will.  If it's theoretical, I will think long and hard about it.  I enjoy cordial disagreement conversation.  If I am wrong, I will appreciatively accept it.  If it comes to it, I can completely disagree with someone and still be great friends.  

On the flip side, I did not mean to imply anything negative about you.  I enjoy your mental strolls, your bs, your puns, and all of the lesser known information you can bring into a conversation.  

[ThomasPowers]

What's the saying about "When the going gets weird, the weird turn Pro!"   I've always considered being called weird a high compliment!

[Frosty]

1 minute ago, Another FrankenBurner said:

I did not take anything you said the wrong way Frosty.  I didn't think you were calling me stupid and I didn't take any offense, I never do.  I was mostly just joking around

I know you weren't Curtis, I was just twitting you a back and taking it as an opportunity to put a little reason out there. Too many folks don't know a correction isn't an insult or attack.  More don't know what honest means or what constitutes misrepresentation. I got carried away is all.

I wish we lived within visiting distance we could have a good time laying some weirdness on: relatives, acquaintances and neighbors. Most of my Nieces call me Weird Uncle Jerry. It's a title I wear with pride, more so than curmudgeon for sure.

Frosty The Lucky.

[Another FrankenBurner]

I am the same Thomas.  I often reply with "Thank you."  That is a great quote I was unfamiliar with.  After researching it, I see I have some reading to do.

Frosty, I'm glad the conversation didn't go too sideways after we had some wires cross.  It seems I am the one who did the misinterpreting.  Which makes sense, me being stupid and all.  

If we lived within visiting distance, I see a lot of yammering at a campfire.  Everyone else hearing the Peanuts teacher.  If we went out to the shop, for some reason, I envision hijinks.  

I'd enjoy seeing your rusty stuff and I'd sure love to show you our shop and all the stuff we are playing with.  Then there would be 3 excited idiots out there.

[JHCC]

1 hour ago, Frosty said:

I know you weren't Curtis

Is that, "I know you weren't Curtis" or "I know you weren't, Curtis"? Makes quite a difference.

For the record, I too am not Curtis.

[Another FrankenBurner]

Uh oh.  The grammar hammer is lurking.  Have you come across the comma's save lives stuff?  Some of it is pretty funny.

[Frosty]

Like dangling a red wiggler in front of a hungry fish, eh? 

Frosty The Lucky.

[ThomasPowers]

We're going to need a bigger boat!

[HojPoj]

And from what I understand, the ones closest to the high temperature regions actually end up burning out of the refractory matrix, their primary role is helping the refractory keep its shape until it can be fired.  

[Another FrankenBurner]

I hadn't thought of that.  I went out and took a look at some broken refractory from an old forge and found it does not have the fibers sticking out of the break.  It is missing through the full thickness.

[Don82]

Have you thought about trying vapor smoothing ABS for molds?  It would significantly reduce the amount of layer lines you would see.  I don't know what acetone does to casting material, but you would also be able to remove the plastic without any heat if it will hold up.

 

PS New to the forum and forging in general. I'm fairly experienced with 3D printers and CAD and this thread has been fascinating.

 

[Irondragon Forge ClayWorks]

Welcome aboard Don82... have you read the Read This First thread located up in the blue banner? It will help get the best out of the forum with tips like editing your profile to show location, as so many answers require knowing that.

[Another FrankenBurner]

I am using PLA as it prints easier and seems to burn out cleaner.  The prints easier reason is also why I don't use the machineable wax filament which would burn out even easier.  Vapor smoothing would be a nice thing to have but PLA requires some fun chemicals for that.  I don't think the layer lines are causing issues and it has been suggested that they may aid in boundary layer turbulence like the dimples on a golf ball but I have no real idea on it all.  I am going to shellac the inside of some, one of these days, to see if the smoothness makes any difference in performance.

Something tells me acetone won't mix well with Kast O Lite or plaster.  Either thing I am casting though, requires heat in the first place.  The molded Kast O Lite has to be cooked to finish and the investments have to be preheated to pretty high temperatures so the metal won't cool upon contact or cause spalling.  

Thank you for the input.  Especially with 3D printing, as I am still fairly new to it all.  

[Don82]

 

I struggled mightily in fluid dynamics, but I think a golf ball moving/spinning through the air vs a stationary object breathing is a little different.  Wouldn't you want as much laminar flow as possible?

I doubt you would see much difference either way.  I was actually thinking smoother molds would make casting easier and there is always points for aesthetics.

I want to get to a point I can test some ideas out but I'm still at the wobbly anvil stage.

ABS isn't hard to print.  It is stinkier, requires a really warm print bed, and doesn't like any kind of draft. I'd be more than willing to print one out if your interested.  I'd just need the CAD file. 

[Another FrankenBurner]

I agree that golf balls and burners are apples and oranges.  I only brought up the golf ball as a demonstration of boundary layer turbulence being a good thing.  It was something suggested by someone else.  I have no idea about such things and kind of doubt it applies here.  Induced air does not travel down that curve in the paths I once thought it did.  

The wobbly anvil stage is a great descriptor.  

The bigger reason I never went to ABS was because of the burnout.  I had read that it leaves more ash, requires a higher temperature, and has a nice nasty black smoke.  I had not heard about it not liking draft, what does it do with that?

 

[Latticino]

Actually the whole boundary layer turbulence thing is directly applicable to burners as well.  As regards flow in a pipe, a limited amount of turbulence is a good thing for reducing pipe friction.  Friction in laminar flow is actually higher than when you cross over the boundary to turbulent flow.  I can dig out the equations if anyone is really interested...

[yotebuster1200]

2 hours ago, Another FrankenBurner said:

(Concerning ABS) I had not heard about it not liking draft, what does it do with that?

 

ABS has a high tendancy to warp when it cools faster in one area than another.  If there is a draft you will end up with warped parts and often prints that have corners pulling away from the print bed.

 

Many people print ABS in an enclosure.  

 

If I wanted smoothed castable parts I would most likely set up to do PLA smoothing it seems to be a much better material for burnout.  Although i wouldn't be opposed to figuring out the setup for lost wax filaments.  Both my printers are direct drive so they probably wouldnt be to tricky to get diled in.  

[Another FrankenBurner]

Thank you for the input Laticcino.  I always get the impression that you are the quiet guy in the room who actually knows about the things the rest of us speculate about.  

Thank you, as well, yotebuster.  I hadn't thought about warping.  PLA is cheap and burns out decently so we haven't ventured down the wax path yet.

[Mikey98118]

AFB,

Welcome to the permanent threads. I had given up, and here you are

Looking forward to lots more fascinating stuff out of you!