# 3D printing an engine frame?



## Harry Mueller (Feb 22, 2022)

I’ve been toying with the idea of printing an engine frame for the Tiny. In looking at the various filaments available I ran into PAHT CF15, which would seem to have most of the qualities required of that purpose. It can handle 150C continuously, with a peak of 180C and is stiffer than most. 
I guess the main variable is the operating temperature of the Tiny and I wonder if the cylinder temps can be held at or below 150C. I suspect they can with enough water cooling.
Any thoughts on this topic?
Harry


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## lohring (Feb 22, 2022)

Prusament PC Blend Carbon Fiber Black 800g | Original Prusa 3D printers directly from Josef Prusa
					






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Lohring Miller


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## Harry Mueller (Feb 22, 2022)

I think this stuff would melt with permanent contact to a cylinder.
Harry


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## GailInNM (Feb 22, 2022)

I think you would be OK with temperature. Consider that the fuel tank on TINY  is bolted directly onto the frame with only a gasket insulating them. As the lighter distillates of gasoline starts boiling at about 100 degrees F (38 degrees C) the fuel tank temperature cannot rise too mulchl abouve this before fuel problems start. Probably 150 degrees F.
I would be concerned about the gasoline attacking the frame chemically however as the bottom of the frame is also the top of the fuel tank. Many plastics do not get along well with gasoline. Probably a PTFE gasket covering the entire bottom of the frame would be adequate protection.
Gail


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## Harry Mueller (Feb 22, 2022)

Thanks Gail, hadn’t thought about the effect of gas on plastics. And I guess a gasket would require a different venting option. Might be worth a look when my printer arrives and I complete a drawing of the frame.
Harry


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## CraigLD (Feb 23, 2022)

I have done something not overly different.  What I did was not what you have tried, but may be of interest to someone...

A number of years ago, I purchased the casting and plan set from myFordBoy for his steam engine.  At the time I didn't have a lathe an so the kit just sat on a shelf.  Since then, I took it out and started to look at working on it.  I now have one of the cheap Chinese lathes, but do have a good set of tools for 3D printing and a fair amount of experience in using them.  So, my thought was to transfer the plans to Fusion 360 (which I am fairly experienced with) and print the parts first in PLA.  This has actually worked out fairly well.  Once all plans were implemented in Fusion 360, I was able able to print each part and assemble it and verified it did work using air pressure.  Obviously this method would never work for use with live stream, but I doubt I will ever use live stream.

Since when I implemented the plans in Fusion, I made sure they were at the same scale as the original, I should be able to swap out each part, one by one, as I machine them in Brass. So the end result is a 1-for-1 replica of the original 3D printed plus the a working Steam Engine as designed by David.


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## awake (Feb 23, 2022)

I seem to recall that both PLA and PETG are resistant to gasoline, but ABS is not. However, don't take my word / fuzzy memory for it ... please apply a liberal helping of salt!


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## Harry Mueller (Feb 24, 2022)

Hey Craig, love what you’re doing! My journey started almost the same way with my wife giving me a Bob Shores Little Herc casting kit. With little experience on my Sherline equipment I started trying to gain enough experience to handle the Herc. I built several air engines and a stirling and am now trying to build the Tiny. I recently made a fatal error on the frame and am looking at restarting it. That’s where the idea of building up the frame with a heat resistant plastic came from. So I ordered a 3D printer that is supposed to arrive today and started learning FreeCAD. I’ve been eyeing the wobbler air engines on thingiverse so that may also be in my future. I kind of feel like I’m burning the candle at both ends but am enjoying the journey.
Harry


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## RM-MN (Feb 24, 2022)

Here's a nice tutorial on using FreeCAD.  It's 1.5 hours long but the first 20 minutes will get you a good start.


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## Harry Mueller (Feb 24, 2022)

I started this one but moved on after a while, it’s actually 2.5 hours long. I’m now at the point where I understand much more so maybe I’ll take another run at it.


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## ddmckee54 (Feb 24, 2022)

Craig:

Be sure when you print the parts that you allow for shrinkage as the plastic cools.  Otherwise your printed parts, and your machined parts will NOT be a 1-for-1 exchange.

Don


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## CraigLD (Feb 24, 2022)

> Be sure when you print the parts that you allow for shrinkage as the plastic cools. Otherwise your printed parts, and your machined parts will NOT be a 1-for-1 exchange.



I have only been using PLA, but the amount of shrinkage actually varies from one brand to another.  I have standardize on one specific brand (but have even notice variation from one manufactured lot to another, but at least that is minimal). A nice thing about 3D printing, if something needs to be tweaked slightly, you just print it again.  Some of the parts were much more critical than others.  For example, the piston valve was much more "touchy" than the crankshaft.  I'm sure I have printed every part at least a couple times.

I go through a lot of rolls of filament.  Its fun because both my wife and I are into it.  Her designs are more "artsy-craftsy" oriented, like gifts for the grandkids.  while mine are more mundane like containers or tool holders.


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## ddmckee54 (Feb 25, 2022)

I totally agree on the difference of shrinkinge between brands.  I've got a roll of red on one printer that prints close enough to actual size when scaled to 103% for printing.  I've got a roll of blue that's a different brand on the other printer, and it needs to be scaled to 104.5% before it's close enough.  When you're printing small parts allowing for shrinkage isn't as important, but on the bigger parts the error REALLY accumulates.


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## CraigLD (Feb 25, 2022)

It's not the best brand out there, but my wife and I have settled on Hatchbox from Amazon.  We have had so many types of filament that have caused clogs on our Sidewinder X1, but it seems to handle Hatchbox the best.  Our Ender-3 V2 seems to handle various brands better.  As you say, on bigger prints variations can really add up. Since the X1 has a 300x300x400 footprint, we use it for our larger parts. But that means there is greater opportunity for clogging.


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## ddmckee54 (Feb 25, 2022)

That's the same size as my MP10, the printer with the blue filament.  Mine's a Monoprice, so it's probably a rebadged clone.

I haven't used it in a while, couple of weeks, and I noticed that the filament has snapped off at the extruder.  I had a spool of red that did that too if I wasn't using it often enough.  If I didn't use it at least every other day the filament would snap between the spool and the extruder - it was a PITA until I got that spool used up. Never had any problems with that spool whille it was printing though.


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## CraigLD (Feb 25, 2022)

My biggest complaint with the Ender 3 V2 is the Bowden drive.  Both my wife and I like the direct drive extruder.  However, she seems to be convinced we need to keep the extra large footprint.  Lately, she has zero in one the new Creality 3D CR-10 Smart Po which does have the direct drive.  Not available yet from US distributors, but is suppose to be later this month.  Everyone needs three printers, right?

Sorry, I now realize that we are high-jacking the original thread.  Maybe there should be a separate area for 3D printer as they relate to model engine building. 

Any thoughts?????


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## cds4byu (Feb 25, 2022)

I bought a direct-drive extruder to replace the Bowden tube extruder on my tronxy 3-D printer.  Cost less than $40 and works like a charm.  

Carl


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## awake (Feb 26, 2022)

Something to consider on a larger format 3d printer is switching to a larger nozzle. You could go all the way up to a "volcano" style with a 1mm nozzle, but if your current nozzle is the typical .4mm, consider switching to a .6mm. You will likely be able to use your existing extruder - it should be able to provide enough heat - but you will cut down your printing time by a fair bit.


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## coulsea (Feb 26, 2022)

I printed a top for an Upshur twin and it works well but I don't run it for very long at a time. I have also printed name plates and painted them to match the engine, putting them in the sun for the paint to dry on a hot day will deform then quite badly.


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## a41capt (Jun 14, 2022)

My sons gave me an Ender 3 V2 for my birthday in April, and I don’t think it’s been off more than a dozen hours since I got it.  What a hoot!  I’ve been printing gears in PLA to experiment with, and when I can get my experience level up to where it should be, I’ll try moving over to Nylon for its toughness in this application.

Im new to 3d CAD, and I’m attempting to learn FreeCAD (loyal Mac user), and I think I’d like to try and draw/print Elmer’s Geared Engine in ABS, PLA, and of course Nylon for the gears.

Anybody got any words of wisdom to share with a newbie 3D printer addict?

John W


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## RM-MN (Jun 15, 2022)

The first "word of wisdom" is that learning 3D CAD is difficult, regardless of the program.  I started with Fusion 360 but figured out fairly quickly that Autodesk was not likely to leave this free to hobbiests with all the features.  FreeCAD may not be as easy to use and may not have all the features but the features are being added, not subtracted.


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## a41capt (Jun 15, 2022)

RM-MN said:


> The first "word of wisdom" is that learning 3D CAD is difficult, regardless of the program.  I started with Fusion 360 but figured out fairly quickly that Autodesk was not likely to leave this free to hobbiests with all the features.  FreeCAD may not be as easy to use and may not have all the features but the features are being added, not subtracted.


Agreed!  About 12 years ago I had a student license for SolidWorks and I was doing real well with it, but that was when I had a Windows computer at work to use.  Powerful program, and as a veteran, I am still entitled to student rates with that program.  However, I’m a dyed in the wool Mac user (since 1986), retired, and no longer have access to a Windows machine with enough RAM, etc.  Therefore, it’s time to re-educate myself and dive headfirst into FreeCAD, which as you’ve said, continues to grow in capability.

We sure do have a great hobby, and I feel very lucky and privileged to be surrounded by such a talented and helpful group of fellow enthusiasts. Thanks for all the guidance folks!

John W


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## Richard Hed (Jun 15, 2022)

RM-MN said:


> The first "word of wisdom" is that learning 3D CAD is difficult, regardless of the program.  I started with Fusion 360 but figured out fairly quickly that Autodesk was not likely to leave this free to hobbiests with all the features.  FreeCAD may not be as easy to use and may not have all the features but the features are being added, not subtracted.


I disagree with you on 3D CAD being difficult.  HOwever, it IS quite helpful to have a good tutorial for whatever program you use.


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## Harry Mueller (Jun 16, 2022)

After starting to learn 3D CAD using FreeCAD this spring, I’ve become fairly comfortable with the basics. I’ve designed and printed a number of useful projects and slso some not so useful ones. Although I’m slowing down on this basement workshop stuff for the summer I plan on going full out again come fall/early winter.
Getting back to my original post, I’m still anxious to explore how 3D printing can be used in building a model IC engine, in my case the Tiny. The frame is an obvious candidate but less obvious are the gears and perhaps even the camshaft. I’ve become comfortable using PLA, PETg and TPU but understand I’ll have to become proficient at using other filament types to continue.
If there is any interest, I’d be up doing a group project on say a small air engine using FreeCAD and a 3D printer. Could be fun!


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## GreenTwin (Jun 16, 2022)

I use Solidworks, and have gotten heavily into 3D printing patterns.
Example below.
Learning 3D was difficult for me because there were no tutorials that showed how to design engines using 3D modeling, and because the concepts were so different than 2D drafting.


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## awake (Jun 16, 2022)

John, 3d printing is indeed fun - and despite what one sometimes reads, useful.

Generally, the articles that say that 3d printing failed to live up to its promise note that people thought they had a Star Trek replicator that would automagically print whatever they needed ... and then they discovered that 3d design requires work.  More about this below ...

I am happy to share my thoughts on 3d printing, with the understanding that this represents only my own experience and needs; mileage may vary. First, thoughts on filaments:

1) PLA is actually stronger than you may think. It is easy to dismiss it as a "beginner" filament, but really, it is quite versatile and reasonably strong. Its one great weakness is that it can deform at relatively low heat, so don't plan to use it for a part that lives inside a hot car, for example.

2) PETG is a nice all-around filament. It is softer and more flexible than PLA, so one might think in terms of PLA being strong but brittle while PETG is more tough and flexible, with better performance in hot environments (though only relatively better than PLA - it might survive the hot interior of a car, maybe, but nothing hotter than that).

3) ABS is not as hard to print as you may think, IF you have a heated bed that can go to 100°C AND you use "ABS glue" (a thin solution of some ABS dissolved in acetone) to wash the plate. But it has poor UV resistance, is smelly when printing (potentially dangerous fumes), and in general I have not found a reason to use it over PETG or PLA.

4) Nylon seems like such a great idea - it should be super tough, great for wear parts - right? Well ... the first problem is, a stock Ender 3 or similar printer is not going to print it successfully. Nylon WARPS like mad; even with a 100°C heated bed, it is nearly impossible to print anything other than a very small part without corners lifting and the part warping - unless you have a heated enclosure, which I do not. Add to that the fact that Nylon loves to absorb water, changing dimensions in the process, and I decided that this filament was not so great after all.

5) POM aka acetal - the common trade name is Delrin - again, seems like such a great idea. I LOVE to use Delrin in machined parts for strength, stability, low speed bearing surfaces, and more. Printing it is ... challenging. Even worse than Nylon, POM is near-impossible to print without a heated enclosure. I have had some success with small parts, such as a linear bearing printed in "vase mode" or a small bushing for a wheel.

6) TPU - flexible filament - I have had success in printing both 85 and 95 TPU (the number referring to how flexible it is). The conventional wisdom is that it requires a direct drive extruder ... but I have been successful with a Bowden extruder. The key is a custom-designed extruder that completely constrains the filament path so that it cannot "squirt out" around the extruder gear. Also key - to either Bowden or direct drive - is greatly slowing down the print speed.

Note that some (most?) of these filaments need an all-metal hotend; depending on the nature of the bed, some of these benefit from some sort of stick/release layer (e.g., glue stick); in particular, without glue stick or similar, TPU can stick so tightly to the bed that it will not release without ripping up chunks of the bed.

Note also that there are tons of variations on many of these filaments, and some of those variations can make a significant difference in strength and/or stability - a particular example being carbon fiber added to the filament. But note also that many fillers, such as carbon fiber, are abrasive and will require the use of a hardened nozzle for best results.

This is getting way long, so I will continue in a second post.


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## awake (Jun 16, 2022)

Continuing on thoughts / experience with 3d printing, with focus on the usefulness and design issues:

I got into 3d printing thinking that it might turn out to be one of those things that is interesting at first, but ultimately goes onto the shelf to catch dust. Nope, definitely not. I don't print every day, not even every week; sometimes a month or more might go by without turning it on. But over and over again, I find myself needing something for which 3d printing is perfect, and the printer goes into action - often with several design iterations until I get just what I want and need.

Some of the highly useful parts that I have 3d printed:

- Boxes to hold gear cutters, drill bits, reamers, taps, etc.
- Boxes to hold electronics and other projects such as an ignition system for model engines
- A teleprompter (works incredibly well)
- All sorts of knobs
- Car parts, such as the gear selector button and a replacement key fob case for my daughter's Honda Accord
- Household items, such as curtain rod holders, handles, funnels, lids, soap dishes
- Jigs and templates for wood and metal working - e.g., a jig to hold items securely at a given angle or shape, or a layout template, or so on
- prototypes - such as an ignition cam for a model engine, or a mounting plate for the band saw, or endless others
- Miscellaneous parts for machines and projects - spacers, shrouds, faceplates, grills, mounts
- And on, and on, and on

Of course, all of these had to be designed. I find myself using two tools for designing 3d printed parts. One is FreeCAD; the other is OpenSCAD. They are very, very different in approach. FreeCAD uses the familiar WYSIWYG sketch-extrude-loft and boolean combine/cut 3d modelling that is similar to Fusion360 and others. Each step of the modelling process builds on the previous step, and you see the effect each step has. OpenSCAD, by contrast, uses a programmatic approach, where one builds up the model by instructing it to manipulate and combine/cut basic primitives. Any time you want to see the results, you have to render the model - essentially rebuilding it from start to finish each time.

It might seem strange, but for many projects I find OpenSCAD to be faster and easier to use. For other projects, FreeCAD is the clear winner.

While FreeCAD is "parametric" - meaning you can adjust various dimensions and features without having to rebuild the whole model - there are limits on what will work. For example, it is generally trivial to change the dimension of a hole or the length of a side. But changing a knob from 5 lobes to 6 is probably going to involve a redesign process. In OpenSCAD, by contrast, _everything_ is parametric. If you build your program correctly, you can set up an OpenSCAD project that lets you enter the desired features of that same knob - OD, height, number of lobes, bolt size, etc. - and it will build the model accordingly. I have built up a collection of such projects, so now when it comes time to make a new box to hold a new set of reamers, or a new knob, or a new button or spacer or bushing, I just plug in the numbers and go.

I am sorry for these lengthy posts, and I hope they do NOT come across as any sort of "look at me"; my goal is rather to help anyone think about all of the ways that a 3d printer can be useful!


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## Bazzer (Jun 17, 2022)

A very comprehensive and interesting report from Andy.

I was very sceptical about 3D printers having seen some work and parts that were truly junk. Then I saw some guy printing carbon fibre filled PLA on Youtube using a Dremel printer, I thought the results looked good and bought a second hand Dremel 3D20 for £200.

This turned out to be money that was very well spent as I have had some very useful parts off of the machine, As with most things it is how you use the machine and apply yourself to the task that determines the result.

The Dremel will print right out of the box with just the print bed needing levelling. After levelling the Dremel can just just start printing the trinket files that come with the machine.

I have only ever printed two free download files, everything else has been original design. I sue the Simplify 3D programme to slice STL models that are produced in a number of 3D CAD packages.

Below are some examples of real work that can be done with good FDM printers feed with good code and using decent filament.

The two orange models are from the moulds produced from the yellow pattern. The upswept wing tips on the models are actually direct 3D printed parts and black arms form part of the aileron control linkage on the same model.

The fuel tank holds methanol and nitromethane fuel and is printed with a good quality PLA, we just drain those tanks down carefully at the end of the day.

Any day now I will be printing some wax for doing some investment castings, that will be interesting.

B.


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## Bentwings (Jun 23, 2022)

Harry Mueller said:


> After starting to learn 3D CAD using FreeCAD this spring, I’ve become fairly comfortable with the basics. I’ve designed and printed a number of useful projects and slso some not so useful ones. Although I’m slowing down on this basement workshop stuff for the summer I plan on going full out again come fall/early winter.
> Getting back to my original post, I’m still anxious to explore how 3D printing can be used in building a model IC engine, in my case the Tiny. The frame is an obvious candidate but less obvious are the gears and perhaps even the camshaft. I’ve become comfortable using PLA, PETg and TPU but understand I’ll have to become proficient at using other filament types to continue.
> If there is any interest, I’d be up doing a group project on say a small air engine using FreeCAD and a 3D printer. Could be fun!


you should be able to find gear models on various web sites you just need to know if metric or imperial some you will get the exact size others you may have to specify . I’m not really up to speed on the new 3D plastic machines . My last experience was in the early days of rapid prototyping. It wasn’t too hard but you had to be mindful of wall thickness .   Some times a sample part was made to check actual sizes then  a minor adjustment allowed very close fits.


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## Harry Mueller (Jun 26, 2022)

Good tips, thanks. I’ve printed several objects recently where exact sizing was important and printing only a few initial layers allowed testing to determine scaling for accurate printing.
Harry


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## a41capt (Jun 26, 2022)

awake said:


> Continuing on thoughts / experience with 3d printing, with focus on the usefulness and design issues:
> 
> I got into 3d printing thinking that it might turn out to be one of those things that is interesting at first, but ultimately goes onto the shelf to catch dust. Nope, definitely not. I don't print every day, not even every week; sometimes a month or more might go by without turning it on. But over and over again, I find myself needing something for which 3d printing is perfect, and the printer goes into action - often with several design iterations until I get just what I want and need.
> 
> ...


Thanks Andy, excellent advice as usual!  I’m trying to draw Elmer’s Geared Engine (I believe it’s number 5), the one with the inner ring gear.  I’ve gotten the ring gear and spur gear modeled already, and will begin the frame valve box, and cylinder.  I’m planning on using a glass dashpot as a cylinder liner, with a graphite piston.  Perhaps printed in ABS to give me a little more temp. resistance (I live in Arizona, and it gets mighty hot!).

Someone mentioned an interest in a group project, maybe this would be a good one to try out.

Thanks again for your usual excellent advice,
John W


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## Bentwings (Jun 26, 2022)

a41capt said:


> Thanks Andy, excellent advice as usual!  I’m trying to draw Elmer’s Geared Engine (I believe it’s number 5), the one with the inner ring gear.  I’ve gotten the ring gear and spur gear modeled already, and will begin the frame valve box, and cylinder.  I’m planning on using a glass dashpot as a cylinder liner, with a graphite piston.  Perhaps printed in ABS to give me a little more temp. resistance (I live in Arizona, and it gets mighty hot!).
> 
> Someone mentioned an interest in a group project, maybe this would be a good one to try out.
> 
> ...


one thing or engine I’d like to see is ageless 18 cyl radial as a clear or see through plastic model . I have never seen a model r 4360 27 cyl . RadialBut 3 d printing could make a desktop model possible


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## awake (Jun 28, 2022)

I would be up for a group FreeCAD project. That would be an excellent way for anyone interested to get a good handle on how to use it.

I know the Elmer engines only by name ... are there any public domain plans available? That would make it considerably easier to do a public group project; if the plans are copyrighted, I would think each participant would have to purchase plans, and the group FreeCAD work would need to be kept private to respect the copyright.

An 18 or 27 cylinder radial might be a bit too big a bite for a group project involving folks new to and learning 3d CAD ... but I agree that I'd love to see a clear model of one!


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## stanstocker (Jun 29, 2022)

Hi Folks,

It appears that a legal version of Elmers Engines is available at:





__





						Resources & Downloads
					

myheap.com - A site for the Do It Your-selfer knowing you do it at your own risk!  Build exciting projects like casting furnace, KRMx01 CNC, JGRO CNC, Wax injector, Joomla development and much, much more!




					www.myheap.com
				




I seem to recall that the family choose to make it available for free, but might be thinking of the Engine Boys books.

In any event, it's good to have these books available, far too many valuable plans or collections of a lifetimes work simply disappear when a magazine or author dies or fails.  Think of all the great plans that were in Modeltec and a few other fallen mags.

Please note that this version of Elmers Engines is not placed in the public domain, just made available by the copyright holder for free.

Best to all,
Stan


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## awake (Jun 29, 2022)

Thanks, Stan. Hmm ... "not in the public domain, but made freely available" - sounds something like one of the "Creative Commons" licenses, which retains the copyright but makes it freely available with attribution.

What say ye all - shall we tackle #5 as a group FreeCAD project? And how should we go about it? Here's an initial thought - not at all sure this is the best way to do it - just to get the ideas flowing:

1) Agree on the order of developing the parts (e.g., first the cylinder, then the piston, then ...)
2) Agree on a schedule, e.g., one week per part
3) Each person who wants to participate can work on modelling the part for the first half of the week; then in the second half of the week, everyone shares their approach / ideas.

Again, I am not at all sure that the above is a good approach or reasonable time frame or anything else; hopefully, though, it moves us closer to figuring out how to proceed.


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## Gedeon Spilett (Jun 29, 2022)

I too love to use my Ender each time I have to make a little gizmo...mainly because it is so easy to reprint a refined version !

there is a pair of beautiful yellow helical gear in a picture above (# 25, Greentwin)  
I wonder if it is possible to model it in 3D with freecad too ?
I'm just starting with freecad...


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## awake (Jun 29, 2022)

Gedeon Spilett said:


> I too love to use my Ender each time I have to make a little gizmo...mainly because it is so easy to reprint a refined version !
> 
> there is a pair of beautiful yellow helical gear in a picture above (# 25, Greentwin)
> I wonder if it is possible to model it in 3D with freecad too ?
> I'm just starting with freecad...


I've not had occasion to try it out, but there is an add-on workbench that can do all sorts of gears, including helical: FCGear Workbench - FreeCAD Documentation


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## timo_gross (Jun 29, 2022)

Bentwings said:


> you should be able to find gear models on various web sites you just need to know if metric or imperial some you will get the exact size others you may have to specify . I’m not really up to speed on the new 3D plastic machines . My last experience was in the early days of rapid prototyping. It wasn’t too hard but you had to be mindful of wall thickness .   Some times a sample part was made to check actual sizes then  a minor adjustment allowed very close fits.



This guys instruction videos on gears for fusion 360 users I found very helpful.  

He is not missing out some of the important details that make the difference between a 3d printed gear pair, and a 3d printed gear that "cooperates" with existing standard gears.


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## timo_gross (Jun 29, 2022)

awake said:


> Thanks, Stan. Hmm ... "not in the public domain, but made freely available" - sounds something like one of the "Creative Commons" licenses, which retains the copyright but makes it freely available with attribution.
> 
> What say ye all - shall we tackle #5 as a group FreeCAD project? And how should we go about it? Here's an initial thought - not at all sure this is the best way to do it - just to get the ideas flowing:
> 
> ...



Is it this one? You are refering to? Nasty internal gear and some smaller parts?



Greetings Timo


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## awake (Jun 29, 2022)

timo_gross said:


> Is it this one? You are refering to? Nasty internal gear and some smaller parts?
> 
> 
> 
> Greetings Timo



I believe that is the one that was suggested above. Personally, I'm open to whatever people want to work on. This one would be more challenging to build due to the internal gear, but it would not be any harder to model in FreeCAD.


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## ajoeiam (Jun 30, 2022)

awake said:


> Thanks, Stan. Hmm ... "not in the public domain, but made freely available" - sounds something like one of the "Creative Commons" licenses, which retains the copyright but makes it freely available with attribution.
> 
> What say ye all - shall we tackle #5 as a group FreeCAD project? And how should we go about it? Here's an initial thought - not at all sure this is the best way to do it - just to get the ideas flowing:
> 
> ...



This sounds like I might even get to learn FreeCAD. 
One big issue is that this is the time of year when I'm totally swamped - - - - its time for construction and gardening. 
Its about like a need for a few clones to get everything done before snow flies!!

I even am just setting up a new system with updated gpu so my system should be less of a hindrance. 

I might just have to follow along because of these present time demands. 
(Maybe stretch the schedule a bit? 2 weeks a part instead of one - - - dunno what would help - - - just have found FreeCAD to be a monster to understand!)


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## lellasone (Jun 30, 2022)

a41capt said:


> Agreed!  About 12 years ago I had a student license for SolidWorks and I was doing real well with it, but that was when I had a Windows computer at work to use.  Powerful program, and as a veteran, I am still entitled to student rates with that program.  However, I’m a dyed in the wool Mac user (since 1986), retired, and no longer have access to a Windows machine with enough RAM, etc.  Therefore, it’s time to re-educate myself and dive headfirst into FreeCAD, which as you’ve said, continues to grow in capability.
> 
> We sure do have a great hobby, and I feel very lucky and privileged to be surrounded by such a talented and helpful group of fellow enthusiasts. Thanks for all the guidance folks!
> 
> John W


If you have a Solidworks background then Onshape could be worth checking out. It's a free web-based cad solution from the same core team as Solidworks, and with a lot of the same interface and feature set (you'll find yourself missing advanced features occasionally, but on the other hand it has much nicer variable handling). The collaboration features have definitly made it the go-to casual CAD program for ME / CS students right now because you don't have all the version control issues you get sharing solidworks projects with a small group. It doesn't seem to have as much traction here though. I still use Solidworks / Fusion for research, but a lot of my personal projects have migrated to Onshape since it runs under Linux and Mac.

All the best,
Jake

Edit:
Onshape Website: Onshape | Product Development Platform
A #25 in Onshape: Onshape

Edit 2: 
The joint free-cad project sounds fun.


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## radial1951 (Jun 30, 2022)

awake said:


> Thanks, Stan. Hmm ... "not in the public domain, but made freely available" - sounds something like one of the "Creative Commons" licenses, which retains the copyright but makes it freely available with attribution.
> 
> What say ye all - shall we tackle #5 as a group FreeCAD project? And how should we go about it? Here's an initial thought - not at all sure this is the best way to do it - just to get the ideas flowing:
> 
> ...


That sounds like a good idea. I will need all the help I can get! FWIW I have just purchased an Ender 3 S1.
Look forward to any progress on the engine here.
Regards Ross G.
radial1951


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## Richard Hed (Jun 30, 2022)

awake said:


> Thanks, Stan. Hmm ... "not in the public domain, but made freely available" - sounds something like one of the "Creative Commons" licenses, which retains the copyright but makes it freely available with attribution.
> 
> What say ye all - shall we tackle #5 as a group FreeCAD project? And how should we go about it? Here's an initial thought - not at all sure this is the best way to do it - just to get the ideas flowing:
> 
> ...


Often this type of agreement is to insure that someone does not try to sell the plans or make commercial work of something they intend to be free to everyone.  That's nice.


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## besty771 (Jul 1, 2022)

stanstocker said:


> Hi Folks,
> 
> It appears that a legal version of Elmers Engines is available at:
> 
> ...


So copyright on Elmer's Engines is very weird.  I got mine from https://www.digitekbooks.com/books/...roduct/25-elmer’s-engines/category_pathway-39

a nice scan...

GB


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## awake (Jul 1, 2022)

ajoeiam said:


> Maybe stretch the schedule a bit? 2 weeks a part instead of one



That might be more realistic, allowing for the inevitable variations in schedule that come along.


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## Curious1 (Jul 2, 2022)

What say ye all - shall we tackle #5 as a group FreeCAD project? And how should we go about it? Here's an initial thought - not at all sure this is the best way to do it - just to get the ideas flowing:

1) Agree on the order of developing the parts (e.g., first the cylinder, then the piston, then ...)
2) Agree on a schedule, e.g., one week per part
3) Each person who wants to participate can work on modelling the part for the first half of the week; then in the second half of the week, everyone shares their approach / ideas.

Again, I am not at all sure that the above is a good approach or reasonable time frame or anything else; hopefully, though, it moves us closer to figuring out how to proceed.
[/QUOTE]

What a great idea.   I do not know enough about FreeCad or any CAD for that matter to contribute anything useful but would definitely learn by repeating any examples that are posted.


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## a41capt (Jul 2, 2022)

I have a partial on the ring gear and spur gear I can share.  I haven’t drawn in screw holes on the internal ring gear, and haven’t added the spur gear changes that’ll include the crank throw yet, but it’s a start!  When I can get to my computer (I’m on my iPad at my cabin presently), I will attach those two files for folks to play with. 

John W


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## a41capt (Jul 2, 2022)

I've been attempting to attach the FreeCAD files to upload, but they appear to be unrecognizable by this site.  Anyone have any ideas why a .FCStd file cannot be attached to a message?


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## krypto (Jul 2, 2022)

Yeah, I was wondering if you could attach the Freecad files in the forum...

Did the flywheel.  I modeled it in the link branch, but made sure it would load and save correctly on vanilla Freecad 0.20 and it's ready to upload. 

Here's what it looks like.


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## a41capt (Jul 2, 2022)

That looks great!  Like I said, I can’t load the files, any help would be appreciated.  I’m using the Mac version and trying to export it in a different format isn’t working either.  Any pointers?

John W


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## krypto (Jul 2, 2022)

Generally, forums like this limit the filetypes you can upload so they don't accidentally start running a warez download site and FCStd files aren't on the approved list.

I added the flywheel file into a zip archive.  You should be able to d/l it, unzip it and load it into Freecad.


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## a41capt (Jul 3, 2022)

Great! I’ll zip them so others can use them.  I haven’t added the mounting holes to the ring gear, or modified the spur gear to add the crank. Perhaps someone better than I am can do those?

John W


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## a41capt (Jul 3, 2022)

I’ll see if I can start on the base next


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## krypto (Jul 3, 2022)

I finished off the gears you made.  It was easier to make a new orbit gear as part objects imported into the Part Design workbench (what I used 99% of the time) are difficult to modify.  The gears seem to fit together well enough.


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## timo_gross (Jul 4, 2022)

The thread is called "3d printing engine frame", and now a "team built" of a freecad model is discussed.  I do want to be annoying, just thinking it might evolve in a helpful sort of a "beginners" guide to freecad. If so; it would be nice if people would find it more easy later.

Should a new thread be started e.g. in the team build section or in software section?



krypto said:


> I finished off the gears you made.  It was easier to make a new orbit gear as part objects imported into the Part Design workbench (what I used 99% of the time) are difficult to modify.  The gears seem to fit together well enough.



Some questions I already have.

If using the original file could you have modified, before importing? I ask, because that might become important for group workflows or when using download files. e.g. from a vendors Cad files. 

If the gears mesh more or less statically in the cad, that does not mean they will work. I learned that the hard way . Spend a lot of time making the gear and then it did not really work properly.
The vido i linked earlier then made the penny drop, I did not consider that the addendum and dedendum of the internal gear must be reversed?
I saw a lot of approaches were the internal gear was obtained by cutting it out of a disc by substraction of a "normal external gear", which ends up in a not working ring gear. 

Greetings Timo


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## krypto (Jul 4, 2022)

I'm not a CAD expert by any stretch, but no, you can't import other program's files.  The universal object between CAD programs is a STEP file, which will just give you a 3D object without any build history.  You can work with that, but with the orbiting gear I mentioned above it was just easier to start from scratch.  Five minutes build tops, once you know how to convert DP to module.





__





						Gear Diametral Pitch, Module Conversion Table Chart | Gear Diametral Pitch | Circular Pitch | Module
					

The following charts convert gear pitch dimensional data to the following: Diametral Pitch, Gear Module, Circular Pitch



					www.engineersedge.com
				




There is no gear mesh (or gear mates) in Freecad so the teeth on the gears are purely cosmetic.  I'm not sure how to simulate the motion of the orbiting gear in assembly either as the most I've done is animate simple levers.  

Since these are 48 DP gears, I'm not sure how to reliable make them in the shop without involute gear cutters of some fashion.  People have been having good luck with printing change gears for the lathe, but they are usually around 18 DP.  These gear teeth are much smaller:






The teeth look a little rough under the scope and this is using the newest Cura and printing profile optimized for fine detail.  Hitting the limits of FDM and a .4mm nozzle. I have a profile for a .3mm nozzle but only had 1 of that size so today's _Adventures in Model Engineering _was to drill-out a few nozzles from .2 to .3mm. That's a really small drill!






Nozzle line-up of .2mm, .3mm (shop drilled) and the default nozzle size of .4mm.  I'm kind scheduled-up for the next few days so the print will take awhile, but I don't think the .3mm nozzle is getting to make a tremendous difference anyway.


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## timo_gross (Jul 5, 2022)

krypto said:


> I'm not a CAD expert by any stretch, but no, you can't import other program's files.  The universal object between CAD programs is a STEP file, which will just give you a 3D object without any build history.  You can work with that, but with the orbiting gear I mentioned above it was just easier to start from scratch.  Five minutes build tops, once you know how to convert DP to module.
> 
> 
> 
> ...



Now we are diving into rabbit holes, but I hope it does not get too confusing. 

In my limited expericence with printing gears, I saw module 1 (approx. 24 dp) work O.K. Those printed gears also worked together with store bought and diy cut gears. Maybe a DP32 can still work, I could try that with some plastic gears. 
I think if the teeth become smaller that that I becomes too detailed. My printer has that typical 0.4 mm nozzle using PLA exclusive. 
To avoid "Elephantfoot" a raft is suggested by people with gear printing knowledge. (it is definitely better to follow that advise)   
The ways to go are a) to cut the gears, if plastic is "good enough" a cutter can be made out of mild steel I guess. b) to just alter the DP of the gears to suit the printing approach. c) use some different sysem to avoid smal involute e.g. lantern Type small gear with the corresponding easier to make internal ring?  

As for the gear file, I was assuming I can "import" respective open the original .FCStd file and that should show the elements that are necessary to change details or add others? 
I was not able to manage to make an internal ring gear in FreeCad yet. How did you do it?

Greetings Timo


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## timo_gross (Jul 5, 2022)

p.s. I managed to make my Ring gear. I had to create a "new body" first, then start the involute gear operation, then pad it. 
Then I made a disc, and substracted the gear from the disc. There is an option external gear true/false. (I hope that makes internal gears).
How to test a ring gear? I think for what we do it is sufficient to just mount two of the small gears in the correct distance on some fixture and rotate the ring gear on them.
I just noticed that I spent hours to design a sprocket in another CAD thing, and that Freecad now has a macro for it.


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## Bazzer (Jul 5, 2022)

krypto said:


> I'm not a CAD expert by any stretch, but no, you can't import other program's files.



That statement needs a little bit of padding out, by far the most common form of 3D file transfer is the STP format, however some 3D CAD systems and Solidedge Community Edition (free download) are very smart and have feature recognition, which enables the STP file to be more than the dumb files that it normally is.

If we take a simple example of a square block with a hole through the middle, normally in a STP file transfer that hole has no intelligence, however Solidedge recognises that the design has a hole and enables that hole to be edited by clicking and altering a dimension figure like it was in a history tree of say Solidworks or Fusion.


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## RM-MN (Jul 5, 2022)

timo_gross said:


> p.s. I managed to make my Ring gear. I had to create a "new body" first, then start the involute gear operation, then pad it.
> Then I made a disc, and substracted the gear from the disc. There is an option external gear true/false. (I hope that makes internal gears).
> How to test a ring gear? I think for what we do it is sufficient to just mount two of the small gears in the correct distance on some fixture and rotate the ring gear on them.
> I just noticed that I spent hours to design a sprocket in another CAD thing, and that Freecad now has a macro for it.


You are correct in your thought that FreeCAD has a switch for making internal/external gears.  My first time making a gear came out as an internal when I intended external and it took a while to discover that switch at which point it turned into an external.


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## timo_gross (Jul 5, 2022)

Hello, 

I am confused, partially because I am also very new (once again) to Freecad, I understand the difficulties to edit an imported stl or whatever foreign file. 
But if I open two files .FCStd I got the bodies on the left model tree in the combo view. These files I am able to save, close open at a later stage and edit them again by for example changing the sprocket pitch from 1/2 inch to 3/16 inch. That what I ment with original file. 



The screenshot shows the minisprocket and a random rectangle block. I saved them separately and then put them back into the same file. Now I can still manipulate both of them.

Greetings


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## timo_gross (Jul 5, 2022)

1st result of todays experiment:


The picture shows gears in module 1 (roughly 24 DP for size comparison). White gear PLA, came just out of the printer (still warm) 60 teeth internal. Made with Freecad without tweak. Export *.stl and sent to printer.
Small metal left, I bought from the gear lady for small fee. Right metal gear I hobbed on the hobby milling machine. They work reasonably accetable together.
Not ZF made for F1 , but good enough for a plastic toy.

2nd result of todays part two of the experiment


Picture shows modul 0.5 gears. ( comparison 48 dp). The brass ring gear is a tedious procedure the white pla gear works sort of almost, actually I am impressed that it is not completely unusable. the small gear is shop made from brass rod.

Verdict: I guess module 1 is already quite small for a 0.4 mm Nozzle with a hobby level FDM printer.

Greetings Timo


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## Steamchick (Jul 6, 2022)

An Engineer nearby (sadly now in the workshop in the sky) made a ring gear by casting Mazak around a change wheel from his lathe. He said the change wheel stayed in the part while he set-it up and machined the ring gear in the lathe, then with some "careful beating" he drove the change wheel out of the ring gear without distorting the ring gear. The finished part was on his Hyper-cycloidal engine using a ring gear instead of a crank. Ran very smoothly! (left hand of the engines in the photo - with the chair as background). 




I like your "new technology" method as well.
K2


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## timo_gross (Jul 6, 2022)

Steamchick said:


> I like your "new technology" method as well.
> K2


I do not like the printed gears that much. Metal ones just are "more real". The brass ring gear was made with my "poor mans slotting head" changing the milling spindle with the slotter attachment, mounting a manual dividing head. Then slot one gap at a time.


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## Steamchick (Jul 6, 2022)

Fair comment Timo. From my experience a majority of "traditional" Engineers  pooh-pooed the introduction of "plastic" intake manifolds, thermostat housings, throttle bodies, etc, as they thought they would lead to high warranty costs due to poor durability. However history has proven the correct use of plastics in such applications as most cars have them as cost effective parts that keep products competitive and available to the budgets of many. I am sure that rubber tyres were laughed at by the wooden-wheel makers... just as steel was inferior to bronze for swords for hundreds of years. But in the right application, appropriately designed plastic parts are "right". I agree that brass is prettier for visible "classic" designs. And all to often, to copy a part in the "wrong" material will lead to early life failures. IMHO Plastic gears should be used in designs appropriate to the hardness, wear and friction properties, tensile and compressive strengths of the plastic. Not simply copies of designs that are suited to brass, steel or other material. And consideration of the temperature, lubrication, impact loading, speed etc. is necessary.
A friend sold his "Mini-mill" because it was full of nylon gears, and his milling, to correct feeds and speeds for the torque of the motor, materials, etc., simply could not take the duty he needed from the machine. But it had been fine when drilling previous models, that didn't have any milling. The gears were Mazak on earlier versions, but obviously just copied in nylon, and failed as expected, on the version he could buy.
Cheers!
K2


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## a41capt (Jul 7, 2022)

I thought that attempting an almost 100% model steam (compressed air) engine from FDM printed parts would be an interesting challenge. I have yet to print the ring and spur gears for Elmer’s #5 geared engine (life gets in the way occasionally), but the emergency gear printed from PLA + for my mini mill functioned fine until a replacement could be shipped. Granted, it was only used for light cuts, knowing it wasn’t as strong as the original nylon gear, but the teeth showed almost no signs of wear.

I figured for a small model that wouldn’t see much stress, PLA printed gears on this application would be fine, and a new challenge to a newbie 3D print guy like me!

John W


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## awake (Jul 8, 2022)

Good grief - I go away on a little trip (just 3500 miles of driving), and before I even get half-way through, y'all have jumped way ahead on this project! Well done, all. I will try to contribute when I get to a place with better internet - it's been very spotty up to now.


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## krypto (Jul 9, 2022)

While I agree that from a craftsman standpoint a nice brass gear is superior, especially for a highly detailed scale engine, it's certainly handy to easily produce plastic gears for testing as material is expensive and shop time is scarce.

Looks like the .3mm nozzle and new profile worked better than I expected!






The gear teeth are much better formed than my previous example and I think this is possibly a working gear set.  It takes forever, but from trying some other non-practical prints with this setup the printer is producing the most detailed work I've seen in 4 years of ownership.






A dime for scale. 






So far the drilled-out .2mm to .3mm nozzles are working great so I might just keep making them as I need them.  I don't think I need many as I mostly do practical prints like bins and such.


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## a41capt (Jul 9, 2022)

After reading some things and watching a video about print strength, I’ve begun printing 4 layer perimeters and top/bottom layers.  I’m finding that infill isn’t nearly as important as outer wall strength when it comes to resisting lateral forces.  Maybe that’s why my simple PLA gear replacement for my mini mill worked as well as it did.

John W


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