The Sabino Compound Engine

[cnr6400]

The gents who built the Sabino's engine knew the score about the assembly/disassembly I guess. They likely didn't want the yoke to be on them! (sorry)       

[crueby]

The gents who built the Sabino's engine knew the score about the assembly/disassembly I guess. They likely didn't want the yoke to be on them! (sorry)     

Better the yoke than...

[ddmckee54]

He/She appears to be taking the disrespect VERY calmly.

[crueby]

Next step on the yokes was to open up the round hole to the end wall:

Then took passes on each side to thin down the lower portions of each one:

The thick section where the two screws are will be trimmed off later. Next will start shaping the profile of the middle section, taking down the curved portioon to where it transitions to the single post out the bottom end....

[cnr6400]

 

The big beestie with the horns is probably just calmly computing trajectory for the starboard-initialized pest impalement subroutine. 

[crueby]

The big beestie with the horns is probably just calmly computing trajectory for the starboard-initialized pest impalement subroutine. 

Water Buffalo horns coming together like pliers.... Nasty!

[crueby]

And this post is brought to you by the letter Y.

Using the rotary table/faceplate setup again, started nibbling out the loser sections of the yokes...

then squaring up the inside corners at the base - they will be cut off from the larger block with the screw holes later

leaving a nice selection of Y's for the scrabble board...

Almost done with these parts - still remaining is to drill the holes in the ends of the little posts at the top that will hold the bearing blocks, trimming off the base blocks, and drilling holes in the stems at the bottom to attach the eccentric arms with. Also some filing/sanding to clean up the tool marks left by the end mill.

[cnr6400]

Those yokes look just great Chris! 

[crueby]

Those yokes look just great Chris! 

Thanks CNR!   Tricky bit is going to be getting the rods, some with curves, to all work out with the same distance from the center of the eccentrics.

[kvom]

From appearances it seems your rotary plate has 3 sets of threaded holes at different distances from the center.  I'd guess you start with stock that matches the set of holes to be used.

[crueby]

From appearances it seems your rotary plate has 3 sets of threaded holes at different distances from the center.  I'd guess you start with stock that matches the set of holes to be used.

Hi Kvom,


The faceplate started with one set of holes, and I have been drilling holes as needed to match the parts  being worked on, so far different cylinders. These faceplates are steel and bought from Penn Industries, they were made for woodturning lathes but have the same thread as the Sherline. Just needed to shorten the unthreaded end of the back post. Much cheaper and stronger than the aluminum ones Sherline sells, cheap enough to drill holes as needed, and toss if they get too Swiss cheesed, they make handy tooling plates. The Sherline rotary table has a handy adapter for the center hole with same thread as the lathe headstock.


Chris

[crueby]

Got the holes for 1-72 screws drilled in the top of the yokes

Then cut off the blocks on the bottom and did some filing/sanding to smooth off the milling marks

Need to get the holes tapped, and drill the holes in the bottom of the stems to take the top ends of the eccentric rods. Then can either make the bearing blocks for the tops, or make the rods, whichever wins the 'what do I feel like making next' contest.

[cnr6400]

Hi Chris, re the rods eccentrics and yokes all getting made and assembled at right lengths and alignments - the humble delta jig may be of use. This is a thing I was introduced to for some tricky mechanism setups. The jig has a fixed pin on one side, and a second movable pin on the other side that fits two sets of dowels at a known "delta" distance. All pins fit the parts that are placed on them with near zero clearance. Parts are put on their respective pins, with the movable pin set on the "further away" dowels and the distance between ends or features where they need to meet can be  measured accurately - the "delta". Parts are trimmed such that when the "delta" distance is subtracted, the ends will be at near exactly the right centres. After trimming, the parts are test fitted on the fixed pin and the movable pin set on the "closer" two dowels to make sure the centres are correct. This kind of jig might be handy for your yokes and eccentrics. 

[crueby]

Hi CNR, 


Sounds interesting, but I don't quite follow all the parts. Do you have a picture of that? For soldered up straps and arms, I've used jigs that sound sorta like that, these are going to be screwed into the straps so I'll do that and do the fitting at the top ends of the arms.


Thanks, looking forward to seeing some pictures or sketches!
Chris

[cnr6400]

Sorry for the delay, just finished the "Saturday jobs". Sketch attached with highlight notes (I hope all needed) for the delta jig. Let me know if anything's unclear still. Cheers CNR6400 

Note that for most accurate measurements, the red end parts and blue end parts need to be excellent near zero clearance fits to the pins, as do the pin fits to the dowels.