1/4 Scale Benz Engine (Inch) Model

[Ken Brunskill]

Attached is the 1st three (3) part designed for an 1/4 Scale Benz Engine Model. I am choosing this scale because I have a nice 6 1/2 Diameter Flywheel already, also because my wife & I are planning to move to a Sr Living Apartment in another few years, making size a factor.

Looking for some comments and insights on the fabrication, being a fair welder in possession of a Miller Econo Arc/Tig welder, I am considering replicating what would normally be castings with weldments, I don't see that as a particularly difficult hurdle, yet the choice of materials, and of course cost needs consideration. So look for the collective wisdom of you my peers.

The 3D model and drawings are being created in Solidworks 2020-2021 Student Version (Being a veteran allows one to get that super powerful program for $20/year!)

 

[Ken Brunskill]

Update on material & fabrication process criteria:

Have decided on using schedule 80 pipe for the Head, Cylinder & Bearing Base. Cost and process is far better with steel than aluminum @2X the cost, or stainless @4X the cost. Simple enough fabrication with TIG welding, plus any consideration of wear makes steel superior to aluminum.

 

[Ken Brunskill]

Now one month and a few hrs. of designing and learning has gone by, the 1st pass design is complete. The bore is 7/8" and the stroke is 1 3/8" the flywheel is the only thing purchased so far, it will end up being 6 1/2" O.D. X 5/8" thick.

Now to get some Solidworks help, so I can get everything to rotate as expected, however being inexperienced as I am, need to get the gears to mesh and the Exhaust Valve Spring to actuate that mechanism, yet more learning to be had .

Still would appreciate any and all comments/suggestions regarding the fabrication methodology. As mentioned earlier expect to fabricate out of Sched. 80 Steel Pipe and most likely braze. However as with all of you, willing to consider other methods and or materials.

 

[deverett]

Ken
If you have access to Model Engine Builder magazine issue 25, have a look at the description and picture of Iqbal Ahmed's fully functional 1/4 scale 1886 Benz Motorwagen.
All made on a Sherline lathe.

Dave
The Emerald Isle

 

[awake]

Ken,

I am sorry that I missed your original post, so just now responding to your question about this fabrication approach.

Can you do weldments instead of castings? Yes, absolutely, with one caveat: just like a fresh casting, you need to allow extra material so that you can machine to size after welding. Even with the most careful use of TIG welding, you will lose any precision machining done up to that point.

Now, take my comments with a grain of salt - I boast the tremendous amount of experience of one - count 'em, one! - completed build, with a second about half-way complete. But my strategy on both builds has been to use TIG welding where it makes sense, whether to save on material or make it easier to fabricate.

 

[Ken Brunskill]

Ken,

I am sorry that I missed your original post, so just now responding to your question about this fabrication approach.

Can you do weldments instead of castings? Yes, absolutely, with one caveat: just like a fresh casting, you need to allow extra material so that you can machine to size after welding. Even with the most careful use of TIG welding, you will lose any precision machining done up to that point.

Now, take my comments with a grain of salt - I boast the tremendous amount of experience of one - count 'em, one! - completed build, with a second about half-way complete. But my strategy on both builds has been to use TIG welding where it makes sense, whether to save on material or make it easier to fabricate.

Good point and that is already in mind, as the plan is to make the weldments to what would normaly be castings. What I am working through in my mind is how to document these, in the pencil/velum days, we exhibited that with. 'phantom' lines showing the casting, now with Solidworks & 3D modeling . . . . yet something new to learn.

 

[mrehmus]

Ken
If you have access to Model Engine Builder magazine issue 25, have a look at the description and picture of Iqbal Ahmed's fully functional 1/4 scale 1886 Benz Motorwagen.
All made on a Sherline lathe.

Dave
The Emerald Isle

Dave,
Actually, Iqbal had only a Sherline mill at the time which I found amazing but a mill can be used as a lathe.

 

[Jasonb]

I'd say welding may not be suitable for all those items, the smaller stuff would be better silver soldered (silver brazed) it is what I would mostly use on an engine of that size with maybe the occasional weld as the first stage of a fabrication then adding smaller parts by soldering that way things don't fall apart when heated.

It is also possible to solder small items to larger ones first as it is easier to get upto soldering temperature, then weld these together particularly with your TIG as the heat is localized and won't melt the solder.

As mentioned above treat it like a casting that you are fabricating then do final machining after soldering though you don't need to worry about draft angles or shrinkage just machining allowances.

This shows how I would do a cylinder in the first post Recreating a Stuart Lightweight, head with bolt bosses similar to yours in this post Recreating a Stuart Lightweight and a forked bearing yoke Woody - but not quite a Forest

 

[Ken Brunskill]

I'd say welding may not be suitable for all those items, the smaller stuff would be better silver soldered (silver brazed) it is what I would mostly use on an engine of that size with maybe the occasional weld as the first stage of a fabrication then adding smaller parts by soldering that way things don't fall apart when heated.

It is also possible to solder small items to larger ones first as it is easier to get upto soldering temperature, then weld these together particularly with your TIG as the heat is localized and won't melt the solder.

As mentioned above treat it like a casting that you are fabricating then do final machining after soldering though you don't need to worry about draft angles or shrinkage just machining allowances.

This shows how I would do a cylinder in the first post Recreating a Stuart Lightweight, head with bolt bosses similar to yours in this post Recreating a Stuart Lightweight and a forked bearing yoke Woody - but not quite a Forest

Jason,
We are of the same mind on the fabrication technique, my plan was/is to tack weld with TIG, then braze to acheive the fillet apearance. it has been many years since I did any brazing, (Silver Soldering yes, but not brazong with brass rod) so am interested in the latest materials.

 

[awake]

Have you tried TIG brazing? I've only experimented a bit, and got it too hot, but seems like a promising technique ...

 

[Ken Brunskill]

Have you tried TIG brazing? I've only experimented a bit, and got it too hot, but seems like a promising technique ...

Hmmm, never heard of it, can you eloborate? I'll do some searching on the Web as well as check in with my Airgas supplier.

 

[awake]

My experience is limited, as I noted, but I'll share what little I know, and hopefully others will correct me where I get it wrong!

TIG brazing uses DC current and argon just the same as for TIG welding steel, but instead of a steel filler, it uses a silicone bronze filler rod - not the same as a gas brazing rod, and no flux needed, though clean metal is (as usual) required. You keep the heat down so that the base material does not melt, but only gets hot enough to melt on the bronze filler. It does not "wick" into the joint the way silver solder does - just lays down on the joint - but apparently creates a very strong joint. As I understand it, you can TIG braze a wide variety of metals, including not only steel and cast iron, but I think I recall reading you can even TIG braze copper alloys - not sure about that.

I seem to remember reading something about an aluminum-bronze filler rod which requires the use of AC rather than DC - I'm not sure when you would use this rather than the silicon bronze - but I am rapidly reaching the outer limits of what little I know or have read!

 

[Doug Cygan]

Hi Ken,
Nice work! You're doing a great job! I've been interested in building one of these too. I have a small hobby foundry setup and a couple of 3D printers to make patterns. If you'd like to share your OBJ or STL files, I can see if I'd be able to make cast aluminum parts.
Doug

 

[Ken Brunskill]

Hi Ken,
Nice work! You're doing a great job! I've been interested in building one of these too. I have a small hobby foundry setup and a couple of 3D printers to make patterns. If you'd like to share your OBJ or STL files, I can see if I'd be able to make cast aluminum parts.
Doug

Doug, now that would be interesting! Let's correspond off this forum so as not to get off topic, email me at [email protected]. BTW what software are you using?

 

[Ken Brunskill]

Feeling quite good about having progressed to this point with Solidworks, I appreciate all the comments and suggestions thus far. Too that point I have the assembly of the parts to the point that the timing can be established as well as the lengths can be established and studied.

This U Tube video show the 3D model operating from TDC (Start of explosion) through one all 4 cycles and back to the start of the explosion. Note the Exhaust Valve opening and closing, and the Intake Valve's slot passing past the corresponding slot in the cylinder.

I certainly feel that having acquired this skill will allow me to analyze models and lessen the frustrations in future builds.

On the fabrication aspect, I am fairly certain I will proceed with the Sched. 80 Steel pipe and Braze the bits to replicate the castings.

 

[Ken Brunskill]

I'd say welding may not be suitable for all those items, the smaller stuff would be better silver soldered (silver brazed) it is what I would mostly use on an engine of that size with maybe the occasional weld as the first stage of a fabrication then adding smaller parts by soldering that way things don't fall apart when heated.

It is also possible to solder small items to larger ones first as it is easier to get upto soldering temperature, then weld these together particularly with your TIG as the heat is localized and won't melt the solder.

As mentioned above treat it like a casting that you are fabricating then do final machining after soldering though you don't need to worry about draft angles or shrinkage just machining allowances.

This shows how I would do a cylinder in the first post Recreating a Stuart Lightweight, head with bolt bosses similar to yours in this post Recreating a Stuart Lightweight and a forked bearing yoke Woody - but not quite a Forest

Jason, appologies for this late response.
Must say that your photos are thorough and speak volumes for the nice work you have accomplished. Trust that they provide insight on techniques and setup to those interested in your approach. Does inspire me to be vigiliant regarding when it comes to fabricating the parts that would otherwise be castings for the 1/4 scale Benz, probably ought to do that for the entire project.

 

[Cddeshon]

Hi Ken. I haven’t seen any activity on this thread for a while; I don’t know if this project is proceeding or not. I’m also looking at the Benz motorwagen (the entire vehicle including the engine) as a possible project. I purchased the Model Engine Builder article but am disappointed in that no detail information was provided. I was hoping for at least elevation drawings, or even drawings with basic measurements so I could ascertain some type of scale.

what are you working from? Do you have a set of drawings, or at least some accurate photos?

I can’t seem to find Anything except for the profusion of videos on the internet. Before I just go out on my own and design something that ‘sort of’ resembles the motorwagen, I’d like to have something concrete to work from.

thanks for any information, avenues to research, or anything else you can and are willing to suggest.

craig

 

[Jasonb]

Should be easy for you Craig, just an Otto on it's side

I'd also be interested in any progress on this one.

I think I may have seen some drawings, will try and find them again, Also on ME there is a guy building a Ford Quadricycle if the Benz is not your only option, few photos may inspire you either way
https://www.model-engineer.co.uk/albums/member_album.asp?a=53499

 

[Ken Brunskill]

Hi Ken. I haven’t seen any activity on this thread for a while; I don’t know if this project is proceeding or not. I’m also looking at the Benz motorwagen (the entire vehicle including the engine) as a possible project. I purchased the Model Engine Builder article but am disappointed in that no detail information was provided. I was hoping for at least elevation drawings, or even drawings with basic measurements so I could ascertain some type of scale.

what are you working from? Do you have a set of drawings, or at least some accurate photos?

I can’t seem to find Anything except for the profusion of videos on the internet. Before I just go out on my own and design something that ‘sort of’ resembles the motorwagen, I’d like to have something concrete to work from.

thanks for any information, avenues to research, or anything else you can and are willing to suggest.

craig

Craig, obviously I have not been actively pursuing the Benz project, partly because I'd not seen much interest, partly because I've been involved with two other projects, finally, and not the least of, my tendency is to have too many irons in the fire. Now in reply to your query:
Being in the USA, having Inch vs. Metric equipment & measuring tools, I wanted to model in about 1/4 scale in inches. I found and was supplied some Metric 1/3 scale drawings, then being the maverick I wanted to avoid castings. Seeing this as an opportunity to do some designing (furthering my SolidWorks skills), I began designing with weldments vs. castings. With a little encouragement I'd continue on. If you or anyone else is truly interested and would be willing to participate in some positive dialog on this design, let me know

 

[Cddeshon]

Hello Ken

Thanks for your timely reply. I can sympathize with having too many “irons in the fire”. I too am in the USA (Raleigh, NC) so my tooling is imperial. I spend most of my social networking time on MEM where I’ve authored several build threads, not so much time here in HMEM.

I would be happy to participate in a dialogue regarding this project; my problems would be that I know nothing about weldments and my design software is Alibre. Not much intersection there. I have no welding skills, and at my advanced age, I don’t see the need to acquire them. I can’t see well enough to weld anymore anyway. I manage to machine from the solid, reasonable representations for most of my “castings”. From the limited views of the Benz engine I’ve seen to date I don’t see an immediate problem with machining a reasonable resemblance of any of the castings I’ve seen on the engine. You do have better documentation than I so I can see where you’re ahead of me in that regard and possibly I might see where machining was not a recommended way.

Also I believe you are making the engine alone; I was thinking of the entire vehicle; though that would require an expansion of my experiences and modeling skills to date as I have no prior experience in making spoked wheels or bending tubing.

Still, I’d be happy to be a sounding board for your thoughts and possibly were you to go your way and I mine, the trading and comparing of information in progress might be interesting.

I haven’t decided upon this project for a certainty; obtaining some level of drawings of the vehicle and engine where I could at least measure relative distances would help me in my decision. I want to get a feel for the relative sizes of the different parts of the vehicle, then choose a scale, and then determine if this is something I really want to pursue or not. I build many of my models from photos of the original… example: the Otto Langen engine I’m currently building. But it would be nice to get some level of documentation before I start seriously thinking of this as a project.


I’ll ask if you would share the source of your metric drawings. I assume these are for the engine alone though if they were for the vehicle that would be phenomenal.

Craig