My new project ...Small diesel engine .

[Nerd1000]

From what I have been reading, people heat the plastic up to get it soft enough to withdrawl from the sand, but avoid overheating the sand.

Apparently bound sand can take a lot of heating.
I think I was reading about sodium-silicate molds getting heated to allow removal of the 3D print.

I have flamed resin-binder molds with a gentle propane flame, and also burned off the moldcoat, without problems, so they are pretty heat resistant.

Hopefully I will not have to get the 3D print fully molten to remove it from the sand.

I am thinking about using a 2-part print, with a removeable round core that takes up perhaps 80% of the print, and then separately print the teeth with a little backing. Then I can remove the center part of the gear, and then heat and remove the teeth.

A bound sand mold I think will be as accurate as a ceramic shell, or almost as accurate depending on how well the teeth spaces ram.

This may be a case where excess binder is used, which makes for a very hard mold or core, but that may be desirable, unless the mold gets too hard and prevents expansion of the molten metal.

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Why not use an investment casting method for this?

 

[GreenTwin]

I am told the slurry has a shelf life of about 1 year.
You have to have a burnout oven, and the shell can crack if the oven is not run precisely.
They generally use a programmed microcontroller on the oven.
The shell has to be heated very hot in a kiln prior to a pour, which can also crack it.
So in short, the investment method can be expensive and very time consuming, and success is not guarunteed.
You have to be willing to pay for investment quality.
Bound sand with a ceramic mold coat approaches investment quality, in a much easier and less expensive way.
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[a41capt]

I’ve experimented with printed gears in PLA, PLA+, PETG, Glass Filled Nylon, and Carbon fiber Nylon, all tested in my HF Mini Mill. No significant wear or breakage on any of the materials, with the cheap filament standing toe-to-toe with the expensive stuff. For a more wear resistant gear, as long as there are no sudden “surprises”, I believe the carbon fiber nylon looks the be about the best.

John W

 

[minh-thanh]

Hi !
Thanks for the comments.
Gears printing, that's also a solution
I don't have a 3D printer yet, so if I want to print gears, I'll buy one
Defect : I have never used a printer...so my experience = 0
I'm also thinking....instead of buying a printer I'll use that money to make a gear cutter
Defect : having to design and build a gear cutter...a lot of work to do
Personally, I prefer metal gears

 

[timo_gross]

Hi !
Thanks for the comments.
Gears printing, that's also a solution
I don't have a 3D printer yet, so if I want to print gears, I'll buy one
Defect : I have never used a printer...so my experience = 0
I'm also thinking....instead of buying a printer I'll use that money to make a gear cutter
Defect : having to design and build a gear cutter...a lot of work to do
Personally, I prefer metal gears

@minh-thanh: did you never cut gears so far, or is it about helical gears?
With "make a gear cutter" do you refer to a machine

or a cutting tool?

http://mikesworkshop.weebly.com/making-gear-cutters.html
"Gears and gear cutting" by Ivan Law ISBN: 9780852429112
I think it is helpful, but probably everybody rolls his eyes, because everybody here has it.

Greetings Timo

p.s. "3d printed gears are evil" do not try to convince me otherwise, do not take the statement too serious

 

[minh-thanh]

@minh-thanh: did you never cut gears so far, or is it about helical gears?
With "make a gear cutter" do you refer to a machine

I have never cut a helical gears
I will make a part or part of a machine to cut gears or maybe make a small machine just to cut gears including helical gears , ...still thinking
Another option: I will go to my friend's place to cut helical gears, he has quite enough machines and tools to cut gears, he is willing to help me, but I don't like to bother him.
About 3d printed gears, I think it will be fine. I have a friend in Vietnam who uses it for his engine and they are quite good.
Personally, I still prefer something that looks...mechanical or metallic

 

[timo_gross]

I have never cut a helical gears
I will make a part or part of a machine to cut gears or maybe make a small machine just to cut gears including helical gears , ...still thinking
Another option: I will go to my friend's place to cut helical gears, he has quite enough machines and tools to cut gears, he is willing to help me, but I don't like to bother him.
About 3d printed gears, I think it will be fine. I have a friend in Vietnam who uses it for his engine and they are quite good.
Personally, I still prefer something that looks...mechanical or metallic

I converted a small vertical mill into my hobbing contraption. To say it was not much work would be self-decepton .... but it works(ish) with some limitations.

Helical gears require more preparation, so I often leave it set for straight gears.

 

[minh-thanh]

Hi All !
An update: I designed more parts, assembled them and see how they look

 

[minh-thanh]

Hi All !
An update:

 

[minh-thanh]

Hi All !
An update:
I can call this engine's plan complete
I will design 2 to 3 more engines that I like and when I will build this engine I will make more parts that it will use for the projects I am planning

 

[a41capt]

I like the looks of that Minh Thanh! This’ll certainly be one to follow and I look forward to your progress.

John W

 

[minh-thanh]

Hi John !
Thank you !
I will use all my knowledge and experience with the previous 2 projects on these projects and try to do the best I can.

 

[werowance]

the main stand, pillar or "block" of the engine (not sure which of the 3 best describe it). Do you plan on casting that or barstock? im intersted in seeing how you handle machining that if done from barstock. im also interested in seeing how you cast it if you go that route

 

[GreenTwin]

Greetings Timo

p.s. "3d printed gears are evil" do not try to convince me otherwise, do not take the statement too serious

LOL, that's funny !

I have "evil" sitting on my desk next to me......... LOL.

I guess this is a throw-down challenge to print some 14" JabsonB helical gears....now how cool would that be.
"BIG Evil", as we call it in these here parts.

Better to have a clearcut opinion than to be all wishy-washy.

All in jest; this is a funny topic for sure.
(Sorry for drifting off topic)

.

 

[minh-thanh]

the main stand, pillar or "block" of the engine (not sure which of the 3 best describe it). Do you plan on casting that or barstock? im intersted in seeing how you handle machining that if done from barstock. im also interested in seeing how you cast it if you go that route

Hi !
I'll make it from bar stock
Currently I have some ideas for processing it, I will let you know when I start processing it.
Some pictures of the new designs

 

[minh-thanh]

Hi All !
Some pictures of the new designs

 

[minh-thanh]

Hi All !
After thinking and checking... everything is fine, I will do the engine body first
How I would machine the body of the engine
1: Milling to size
2: Milling removes excess material
3: Use a lathe to machine the outer surface and middle hole
4.5 : Milling to size
6,7,8...will follow when I get there

 

[Basil]

I like the design. Going to be a nice engine.

 

[minh-thanh]

Hi All !
I have bought some materials for the 2 diesel engines I have designed and will build but I have some work to do, I will return to the project in about 2 , 3 weeks

 

[GreenTwin]

I worked on a Myers steam oscillator casting kit, which is similar to a Cretors No.06, and it was a bit interesting to hold the frame.

I am not sure whether this would be applicable, but I do recall it being a bit awkward to grip.

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