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My first stem engine build

YYCHobbyMachinist said:
Ahhhh… the plans for the WigWag are in mm. Are there inch size plans available?

Trying to size out the stock required in inches is proving to be a challenge!

Craig
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I had to fudge my sizes a wee bit to accommodate the pieces I had on hand. I think the critical dimensions are the distances from the center of the crankshaft and piston travel in the cylinder. I'm certainly no engineer, but, those are the ones I focused on getting really accurate. I don't think stock size is critical.
Just my two cents. Someone with more experience feel free to correct me
 
Brian H said:
I had to fudge my sizes a wee bit to accommodate the pieces I had on hand. I think the critical dimensions are the distances from the center of the crankshaft and piston travel in the cylinder. I'm certainly no engineer, but, those are the ones I focused on getting really accurate. I don't think stock size is critical.
Just my two cents. Someone with more experience feel free to correct me
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Ya, I concluded the same thing and have started to cobble together a vertical wigwag. Did you use bronze bushings/bearings as per the plans?
 
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Brian H said:
I think that's awesome. Did you find working on such a small scale to be difficult? I am very intrigued by miniatures but wasn't sure my skills were up to the task.
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No not so bad actually. I would encourage you to try and don't be hesitant of your skills, you quickly gain experience and skills with these little simple projects and the materials they use are minimal.
 
You can hobble together a wobbler pretty easy, Mr Peterson aka mrPete222 aka tubalcain has lots of helpful and varied Youtube videos on the subject, including a minimal tool version with washers for fly wheels and large multi piece end-table sized free standing one.
 
YYCHobbyMachinist said:
Ya, I concluded the same thing and have started to cobble together a vertical wigwag. Did you use bronze bushings/bearings as per the plans?
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Yes I did. PA has a nice selection of bronze bushings for a very reasonable price.
Since I can't find any brass here in Saskatoon I've had to get creative.
 
Brian H said:
Yes I did. PA has a nice selection of bronze bushings for a very reasonable price.
Since I can't find any brass here in Saskatoon I've had to get creative.
Click to expand...

BUILD1.JPG


This is my build so far, working on the piston as we speak.

Did you ream the axle holes as per the plans? I don't have reamers.
 
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YYCHobbyMachinist said:
View attachment 8009

This is my build so far, working on the piston as we speak.

Did you ream the axle holes as per the instructions? I don't have reamers.
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Very Nice. Yes, I did ream the holes. I got a set of metric reamers from Banggood for pretty cheap. I don't think it is absolutely necessary tho. I found there is alot of leniency with tolerances. The tighter the tolerances the smoother it runs.
 
Brian H said:
Very Nice. Yes, I did ream the holes. I got a set of metric reamers from Banggood for pretty cheap. I don't think it is absolutely necessary tho. I found there is alot of leniency with tolerances. The tighter the tolerances the smoother it runs.
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If you used metric reamers where the heck did you get metric silver steel from? My lathe doesn't cut metric threads, so I'm going to have improvise some how.
 
YYCHobbyMachinist said:
If you used metric reamers where the heck did you get metric silver steel from? My lathe doesn't cut metric threads, so I'm going to have improvise some how.
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I lucked out and had a broken drill extension that polished to 6mm. And my lathe is all metric since it's a Chinese import. I have trouble doing imperial threading...I'm actually looking at getting a 3D printer to make the change gears I need since they can't be purchased as far as I can tell
 
By silver steel I assume you mean drill rod (as opposed to ground hardened shaft stock)?

KBC sells metric O-1 drill rod for about the same price as comparable IMP size. Metric only comes in O-1 at KBC whereas IMP drill rod is available in O, W or A
For example https://www.kbctools.ca/itemdetail/1-950M-004
Just as a heads up, they do fall within the tolerance on diameter range but I have measured eccentricity so its best to lap them a bit so they are truly circular if running in a bushing.

Ground & hardened drill rod can also be purchased, but they are short lengths like 3-4". You can grind them but not practical to machine them.
 
I'm not sure what change gear options you have, but AIUI a lot of "Imperial" lathes can cut threads that are close enough to metric sizes to work just fine. For example, my ancient Atlas 618 has these options:

618 metric threading.jpg

The pitches are not exact but they are usually good enough for real world use. Or so I read.

Craig in Oakville
 
trlvn said:
I'm not sure what change gear options you have, but AIUI a lot of "Imperial" lathes can cut threads that are close enough to metric sizes to work just fine. For example, my ancient Atlas 618 has these options:

View attachment 8011
The pitches are not exact but they are usually good enough for real world use. Or so I read.

Craig in Oakville
Click to expand...
I do have the list with all the configurations for my lathe I just can't find the correct size gears with the correct number of teeth
 
Could you not just go imperial and use a 1/4" (6.35mm) then you are threading 1/4" on your lathe.....reamer would be pretty cheap....

Metric system sucks for building things..IMO
 
RobinHood said:
I wonder if you could make yourself a D-bit single lip cutter of appropriate size to finish the axle bushes after drilling.

Clickspring shows how to make one here: http://www.clickspringprojects.com/d-bit-single-flute-milling-cutter.html
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I used this d bit in the most rudimentary way, I used a tent peg, and rocks to hammer and shape it then drilled a 2”deep hole in wood by hand. It worked great fit the rope I needed and only took 2 hours.

Chris does a better job on his but I can attest that the tool does work
 
Bofobo said:
I used this d bit in the most rudimentary way, I used a tent peg, and rocks to hammer and shape it then drilled a 2”deep hole in wood by hand. It worked great fit the rope I needed and only took 2 hours.
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ok.... now you have to tell us what motivated this endeavor.
 
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