In the next few months I'll be uploading components that can be used for lost_PLAcasting a 3 cylinder single acting unaflow poppet valve steam engine. At full scale the engine has a 66mm bore and 50mm stroke and measures 400mm long. The crankcase takes about 8 days to print and uses over 2kg of filament. The engine has a swept volume equal to that of a Stuart Swan twin double acting steam engine.
Remember to check back from time to time to see if the version numbers of various parts have changed: it is evolving!
This engine will be presented in two forms:
1) one for a plastic display model that may be run with an electric motor
2) one with material added to produce Lost PLA casting pieces that can be machined to final tolerance after they are cast. All of these files have a "C" prefix.
--I'm prototyping in 1/3 scale and I'm building the display model first to check that parts fit together and work smoothly with one another. The first Lost PLA version will be printed in 1/2 scale and castings will be machined in my shop.
Crankcase top and bottom can be printed with support touching build.
The cylinder can be printed without a raft but in the orientation shown and with support 'touching buildplate'.
Print the crankshaft and cam shaft in the same way.
Flywheel can be printed with support from table only. Holes can be tapped M4. The keyway is probably too small.
IF you decide to build the full size engine you'll need to get a pair of meshing spur gears to couple the cam shaft to the crankshaft; be aware the two shaft bores are different. Here's one source: https://www.khkgears.us/catalog/product/SS2.5-30
--If you want to build the engine with a sliding camshaft you'll need to replace the crankshaft gear with the 'long gear' which will keep the sliding camshaft synched to the crankshaft.
If you want someone to print the larger parts that don't fit most printers contact my pal jetdillo: https://www.thingiverse.com/jetdillo/about
1) Camshaft replaced with another with greater contact area on each lobe
2) Flywheel redesigned to clear camshaft
3) Conn rod lengthened, redesigned and made to better fit between crank webs
4) Conn rod cap made narrower to fit between crank webs
5) Crankshaft redesigned to have counterweights
1) Enlarged mounting holes on base of cylinder assembly
1) Redrew Cylinder Sleeve adding exhaust ports
2) Increased cylinder bore to finish dimensions
3) Uploaded cylinder sleeve drawing
4) Uploaded two photos of 1/3 scale engine coming together
5) Uploaded new cylinder with valve trunk
1) Uploaded Valve Cover
1) Deleted obsolete files
2) Uploaded new cylinder sleeve drawing with holes moved 6mm to align better with cylinder exhaust slot
3) Uploaded new upper crankcase drawing with enlarged cam follower openings and pads added for placement of cam follower clutch rod.
4) Uploaded alternate cylinder with narrower profile.
4) Uploaded alternate valve cover with narrower profile.
1) Replaced cylinder with one 15mm shorter and with a narrower profile
2) Replaced cylinder liner with one 15mm shorter
3) Replaced valve cover with one to match slimmer cylinder
4) Replaced conn rod with a longer one
5) Replaced piston with a longer one that prints without support
6) Added wrist pin
7) Printing Notes:
-At 1/3 scale print cylinder sleeve to 33.5%
-At 1/3 scale print piston to 32.5%. If wrist pin is too tight bore piston with a #21 drill
-At 1/3 scale print cylinder to 34%
-At 1/3 scale print valve cover to 34%
-At 1/3 scale print upper and lower crankcase halves to 34%
1) Replaced piston_04 with piston_05 with slight bevel to eliminate sanding the lip to fit sleeve
2) As of now some parts are DONE and won't be modified any further. These include:
3) Parts that are still evolving are as follows:
4) Parts that have yet to be added:
-Cam_Follower_Lifter_Fork (3 needed)
-Cam_Follower_Lifter_Lever (3 needed)
-Cam_Shaft_Shift_Lever and all its mounting tackle
1) Uploaded Crankcase_Upper_19 which fixes cam follower installation problem
2) Uploaded Crankcase_Lower_04 which has an oil drain
3) Uploaded Cam_Follower_Bushing_02; six are needed
4) Uploaded Cam_Follower_Bushing_01. Be aware this one will be evolving
1) Deleted Crankcase_Upper_19
2) Uploaded Crankcase_Upper_20 which has much larger cam follower holes
3) Deleted Cylinder_19
4) Uploaded Cylinder_19L which is 30mm longer than previous version
5) Deleted Cylinder_Sleeve_05
6) Uploaded Cylinder_Sleeve_05L
7) Deleted Cam_Follower_Bushing_02
8) Uploaded Cam_Follower_Bushing_04 which are much larger
9) Uploaded Cam_Follower_04
8) Deleted Conn_Rod_04
9) Uploaded Conn_Rod_05 which is 30mm longer
1) Replaced Conn_Rod_05 with Conn_Rod_06 which is 1mm shorter to improve exhaust
2) Replaced Flywheel_03 with Flywheel_04 with larger access holes to tap inner holes and a larger keyway.
3) Replaced Lower_Valve_Guide_02 with Cam_Follower_Bushing_06
3) Replaced Cam_Follower_04 with Cam_Follower_05 which is 15 mm longer
1) Replaced Valve_03 with Valve_04 which has notch moved further up the stem to clear the top of the pocket in the top of Cam_Follower_05
2) Uploaded Cam_Follower_Lifter_Pivot_Mounts_02
3) Replaced Cam_Follower_Bushing_06 with Cam_Follower_Bushing_07 with larger mounting holes
3) Replaced Cam_Follower_05 with Cam_Follower_06 with shallower top pocket.
4) Replaced Crankshaft_Long_Gear_01 with Crankshaft_Long_Gear_02 with setscrew holes
5 Uploaded Valve_Spring_Washer_01
1) Replaced Valve_Spring_Washer_01 with Valve_Spring_Washer_02
2) Replaced Cam_Follower_06 with Cam_Follower_07
3) Uploaded cross-section image of Cylinder__19
2019_11_05: Have decided that the steam path to the top of the cylinder is too convoluted, making it hard to cast and hard to machine once cast. I've redesigned the whole top end and this also provides more room for a valve spring.
1) Replaced Cylinder_19 with Cylinder_20L
2) Replaced Valve_Cover_14 with Steam_Inlet_Layer_04
3) Uploaded new Valve_Layer_05
4) Replaced Valve_04 with Valve_05
1) Replaced Crankcase_Upper_20 with Crankcase_Upper_21 which has an attachment pad for the cam traversing lever.
1) Replaced Crankcase_Upper_21 with Crankcase_Upper_22 to solve interference issue with flywheel
2) Replaced Cylinder_20L with Cylinder_21L to fit narrower valve stems
1) Replaced Crankcase_Lower_04 with Crankcase_Lower_05 correcting hole misalignments and matching end profiles.
2) Replaced Crankshaft_08 with Crankshaft_09 with a hex on one end so it can be run in with a hand drill.
1) Uploaded Crank_Web_01 for anyone who wants to build a crankshaft from steel or brass tubing. At 1/2 scale the two hole diameters are 8mm and 11mm which are really close to 5/16" and 7/16".
2) Uploaded Cylinder_Evolution_04.png illustrating how the steam intake path has evolved.
3) Uploaded Cylinder_21L
4) Uploaded Steam_Top_01
1) Uploaded Camshaft_05 which is solely to test fit of Cam_Follower. It will be swapped for a proper design when I come up with one.
1) Uploaded sketch of reversing mechanism; .stl files to follow in a day or two.
1) Uploaded some parts for Reversing Mechanism; with these the camshaft can be traversed fore and aft, assuming cam shapes are blended together. If discrete cams are used more stuff is needed and I'll upload those in a few days.
1) Finally figured out how to apply raised lettering to curved surface and uploaded Upper_Crankcase_23 with identifying label about the engine.
1) Uploaded Crankcase_upper_26 which corrects some drawing mistakes and which makes bolting top and bottom sections together easier by redoing holes on both ends.
2) Uploaded Crankcase_Lower_07 with bolt holes redone on both ends.
1) Uploaded Cylinder_23, correcting minor mounting hole misalignment
2) Uploaded Crankcase_Upper_27 correcting misalignment of outermost crankshaft guides
3) Uploaded Crankcase_Lower_27 correcting misalignment of outermost crankshaft guides
1) Uploaded Manifold_01
1) Deleted Manifold_01
2) Uploaded Intake_Manifold_01
2) Uploaded Exhaust_Manifold_01
Uploaded 15 parts all modified for Lost PLA Casting. Enjoy!