Finger Treadle Engine

[cfellows]

So I've settled on my design and began construction of two finger treadle engines for my two sons.  I started out by 3D printing a frame.



 But I didn't care for the quality of the print and decided the whole thing really needed to be made out of metal.  I started out with 2" x 3" x 1/4" angle iron for the engine frame sides.





I cut the long leg off the angle iron to form the base of the frame side.  Next I milled and polished the cut edge that would be the base.  I also laid out the cut lines and used a 1/2" end mill to drill the holes that would form the radiused edges.  (Please ignore the obvious error in cutting the holes...)



I made the main bearing journals out of brass, then used my metal cutting bandsaw to cut the remaining waist away from the frame sides...





And here's a bit of a mock-up to give you an idea of the design.



The finished models will have 3", 5 curved spoke flywheels, 2 on each model.  I'll be using my CNC mill / drill to cut the flywheels from 3" diameter brass round.  Then I'll need to do some finish milling and grinding on the steel frame sides to finish them up.

More to come...

Chuck

[Robert Hornby]

Looking very nice Chuck, I wonder why the 3D print came out a bit rough?
Robert

[cfellows]

Thanks, Robert.  I think the outer walls of the 3D print need to be thicker so the infill shape doesn't bleed through.

Today I got the frame sides cleaned up and mounted to a base of 3/8" thick x 2" x 5.25" cold rolled steel. 



The sides were attached to base with counter-bored socket head cap screws from underneath.  I also had finished turning the outer crankshaft halves.  These were turned from 20mm 12L14 steel.  The connecting rod journal will be installed with Loctite and perhaps pins.

Chuck

[Noitoen]

Nice work. Would't a couple of HDD salvaged bearing do a better job than brass journals? It would give a much smoother ride.

[cfellows]

Nice work. Would't a couple of HDD salvaged bearing do a better job than brass journals? It would give a much smoother ride.

Thanks.  Yeah, i made the brass journals mostly for looks.  Theyree large enough that I can bore out the inside and insert a ball bearing race.  That's probably what I'll wind up doing.

[Brian Rupnow]

Chuck--It's great to see you up and running with a project. Hope you are feeling well. I haven't seen you on the forums for a while.---Brian

[cfellows]

Chuck--It's great to see you up and running with a project. Hope you are feeling well. I haven't seen you on the forums for a while.---Brian

Thanks, Brian, good to be here.  I've been active in my shop, but have been working on RC cars and didn't think there was anything worth posting here.

Today I cut the 3" diameter blanks for the flywheels...



They'll require some lathe work then on to the CNC mill to cut the spokes.  Might try a time lapse video of the CNC work just for the fun of it.  I also got the main bearing journals attached today.  Had to do some rework on the steel frame and the journals to get everything square and lined up. 



Gotta say I am pleased with the results.  A 3/16" round rod of tool steel slides nicely through both journals and rotates with no drag or interference.  Now if I can just get the crankshafts assembled nice and straight...

[cfellows]

I got all 4 of the flywheels cut to shape.  Still need to do a bit of clean up.



They are 3" OD.  the rim is 0.375" front to back and 0.25" outside to inside.  The spoke web is about 0.125" thick.  The hub is 0.4375" diameter and about 0.54" front to back.  I have a fusion 360 drawing of this flywheel, but haven't been able to export an IGES or STEP file for some reason, I keep getting an error.  I have attached a DXF file which I was able to load into CAMBAM for creating the gcode file.

Here is a video of me cutting all the spokes on one flywheel.  All the profiling was done on the lathe.  The CNC was only used to do the spoke cut-outs.  Ignore the 23 minute video length.  For some reason during editing, I managed to get two copies of the video back to back.  The flywheel only took 11 minutes, 48 seconds to cut all 5 spoke cut-outs.  If you watch to the end of the video, you'll see that the MACH3 software somehow got the Z reference screwed up and did the full 1/8" deep cut-out in one pass.  I'm surprised the 1/8", 2 flute, solid carbide end mill survived, but it didn't seem to struggle or deflect at all.

<a href="https://www.youtube.com/watch?v=n3gQBgQyru8" target="_blank">http://www.youtube.com/watch?v=n3gQBgQyru8</a>

Chuck

[crueby]

That flywheel is just beautiful! You have the spoke proportions on the nose.


 

[b.lindsey]

Chuck, those turned out amazing!!  What you do with angle iron on this build and others is impressive as well.

Bill

[cfellows]

Thanks, guys, for the kind words.  I had to modify two of the flywheels.  I realized when I started putting things together that curved spoke flywheels with one side of the hub longer than other have a left and right hand model.  Well, I made all right hand models.  So I had to shave off the hub on one side of two of the flywheels, then bore out the center hole and solder in new hubs on the other side.  Turned out OK.

Here's a pic with the modified flywheels, partially assembled...



Gotta finish up the crankshafts and get started on the connecting rods and treadles.

Chuck

[cfellows]

I've decided to make the crankshafts from one solid piece.  Not the easiest thing in the world, but the method I have the most experience with...



After turning the connecting rod journal and cutting of the waste pieces, I turned a couple of pieces of 1/4" drill rod to the exact length of the gap between the webs, then super glued them into position so when I mount the crankshaft between centers to turn the two main's journals, the gap won't squeeze together.  Never tried this method before, so hopefully it will work as expected.

Chuck

[crueby]

Neat idea, be watching to see how it works out.

Now, you should have left out the part about gluing in the spacers, and seen how many questions you got about how the heck you turned that part!!

[cfellows]

Thanks!  Here's a picture of the progress on the first crankshaft...



And here's a video of some of the turning...

<a href="https://www.youtube.com/watch?v=Knedhq47950" target="_blank">http://www.youtube.com/watch?v=Knedhq47950</a>

[cfellows]

One last picture for the day.  I thinned up the webs, turned a clearance shoulder on each side, and ran the edges over the belt sander to polish them up.



Still need to turn the mains journals down to final size.