Cotta Transmission Cutaway Model

[crueby]

Back in the shop this morning, first steps on the shifter assembly was to cut out all the parts from bar stock and trim the ends. Here are all the rough cut parts - as they used to do in some text books, the rest of the operations are left as an excercise for the reader!   

Seriously, the thicker bars laying flat will be the supports for the other parts, the thin ones standing up will be the shift gate plate, the rods will be the shifter lever, and the little parts are the pivot and support blocks.
After getting the parts trimmed to length, I drilled the ends of a bit of roundbar and radiused the ends to get a start on the shifter knobs. Here they are stuck on the ends of the rods with some retaining compound, when that has cured I'll trim the ends round - just freeehand cutting and using a file to smooth the cuts out fair.

While those are curing up I can get a start on laying out and drilling holes in the other parts...

[crueby]

The loctite on the gear shift knobs was set up enough to turn the ends. The shop elves think they make great brass lollipops!

[cnr6400]

  Doing their Frank Sinatra and Dean Martin duet karaoke number on the big new microphones, eh? 

The levers look great! 

[Michael S.]

Very well done sticks for the drums! Oh sorry, I mean gear shift levers.
The Meesing balls both look very similar.

Michael

[Kim]

They do look like drumsticks, don't they?! 

Enjoying watching this all come together, Chris. 

Kim

[crueby]

Thanks guys!   Though I did have to send them back outside to get the drumsticks again, the elves were using them to beat on the squirrels...   

[crueby]

Last parts for the day: got the holes drilled in the mounting block and the shift gate plate. The pattern in the plate will be done last, I want to double check it with a cardboard template once the other parts are made in case there is any adjustment needed, the gate openings are very sensitve to angles and heights. This picture shows where the shifter will sit on the corner of the transmission. Also still need to trim the input shaft to final length, you can see in the foreground that it sticks out pretty far still. I wanted to wait on that to ensure that it would not be a knuckle scraper!

[crueby]

And the shift rod gimbal has been made up. To get a longer side to side throw than front/back throw between the two control rods, the two pivots are offset from each other.

Next will make the pivots to hold these to the mount blocks, and then the pins in the ends of the control rods for the shift lever to push against...

[cnr6400]

 

[bent]

 

[crueby]

Thanks guys!

This morning saw the little bars added to the ends of the control rods, for the shift lever to push on as it goes back and forth. I still need to make the detent to hold one of the rods in the center when the other is moved into gear, so it can't wander. I'm thinking a single ball bearing that engages a shallow slot on the rod should do the trick, I've got a box of assorted sizes of steel balls. Either a spring or just a piece of rod as a weight on top of the ball. A little experimenting should show what works, it just needs to hold well enough to keep the rod in place in the center position. After that, I'll cut the slots in the shift gate plate. Nearly there!

[Vixen]

Hello Chris,
 
Spring loaded ball detents are a great idea. A brass 'H' gate plate, engraved with 1,2,3,4;  will really complete this cutaway model.

Mike

[crueby]

Hello Chris,
 
Spring loaded ball detents are a great idea. A brass 'H' gate plate, engraved with 1,2,3,4;  will really complete this cutaway model.

Mike

Yup - I was planning on engraving the numbers on the plate, R, 1, 2, 3 for this one. I have an old pantograph engraving machine that will do that job nicely! For the detents, I'll do some experiments to figure out how deep to cut for the ball bearings I use, don't want it too hard to move from center. The ones on my tap wrenches need a hard rap to disengage, but those grooves are really deep. Should be easy to find a sweet spot for it. Might put another detent at the gear-engaged position too, so it stays in gear when the elves are drifting the lombard truck!

[Kim]

Very neat to see the drumstick come together in the model!  Really nice work, Chris! 

Looking forward to the video! 
 
Kim

[crueby]

Very neat to see the drumstick come together in the model!  Really nice work, Chris! 

Looking forward to the video! 
 
Kim

Me too, should be soon!