Re: pic: NanoShifter
 

As for an encoder:
-It could go on the other end of the wheel shaft
-You could use a code wheel on the wheel itself
-You could use a gear tooth sensor on one of the gears - This does not know post-shift speed


As for not all shifting:
-How would this issue be any different than that of using (2) Dewalt transmissions per side, except that pneumatic shifters are faster than servos?
-I think, using the highly reliable Andy Baker shifting transmission design, and properly protecting the pneumatic system from damage, you should be OK if you don't explicitly detect and handle the issue of one transmission not shifting.


Another issue I may have missed: How do you get everything into the box? It looks like it is impossible to assemble, specifically the shift shaft.

Re: pic: NanoShifter
 

That's the question I've been waiting for. It's bit like building a ship in a bottle. I think I can be done but I haven't thought through every step. This would be a good excersize for someone - explain the exact sequence of putting the shift shaft together.

Re: pic: NanoShifter
 

please to give us the CAD file?

Re: pic: NanoShifter
 

Yes! Please to give to everyone! :D

Re: pic: NanoShifter
 

Step 1: Press 3/8" bearing

Step 2: Insert small shifter gear into tube, align and insert shift shaft with dog assembled.

and

Brick wall..

even if you flipped the last bearing there is no way to get the other gear on the shaft. It may have some way out there solution but I don't see it. The hex boss on the shifter shaft creates a mechanical limit.

May I suggest putting a hole large enough for the gear (and entire shifter assembly) through and use 1/8" plate to patch the hole. To determine alignment use pins and threaded inserts for fastening in such a compact space. You may have to do this to insert all shafts and gears. Using the tube to determine spacing and fit, Swiss cheesing the outer wall and making a single face plate to close off the assembly.

Re: pic: NanoShifter
 

Step 1 was good - try something else for step 2.

Re: pic: NanoShifter
 

I'll send it to Matt at FRC Designs.

Re: pic: NanoShifter
 

If the press fit between the shift gears and their bearings was light enough, and the diameter of said bearing on the low gear side was less than or equal to the diameter of the dog AND less than or equal to the diameter of the hole for the flanged output bearing, this would work:

(A quick check of AM shows that the dog gear has an OD of 1" and the low gear uses an R8 bearing (1.125") - this would work possibly)

1. Insert the rear bearing (piston side) and press it in
2. Insert the two shifted gears into the tube
3. Assemble the shift shaft with the bearings, dog, and other bearings
4. Insert through front (output side) of transmission, pressing bearings into gears as you went
5. Press on output bearing from the outer side - If I am correct, this will be fine as the wheel will hold the bearing on
6. Assemble the cluster shaft like the current way AM does it
--One bearing is flanged and inserted first
--All of the gears are inserted and the shaft is inserted from the outside, through all of the gears into the inner bearing
--The outer bearing is inserted, and the two screws hold it
7. The CIM motor is the easiest part.
8. Assemble the shift linkage - This is standard AM shifter stuff

Re: pic: NanoShifter
 

Both the large gear idle bearing and the shaft bearing have the same 1.125" OD but both also have the 1.125" OD flange (I think). So up to this point you could fit the shifter shaft and the dog though the bore in the large gear but inserting the idle bearing is another road block.

EDIT: never mind the small gear is the one with flanged bearing but now the concern is with the lip that the bearing bottoms out on on the larger gear. Is this ID large enough to allow the dog to pass through.

Re: pic: NanoShifter
 

You're close:

The dog and the bearing for the small gear need to be in before the shaft.

You have to be careful how you press the bearing for the large gear in - press on the outer race only.

How do you get the spring pin through all three pieces (dog, output shaft and shift shaft.)

Re: pic: NanoShifter
 

The idler bearing does not have a flange but the bearing in the housing does. Notice that there is a sleeve around the bearing so the flange will fit through the hole. You can't see it in this render, but there are two screws like the one on the cluster shaft holding the output flanged bearing in place.

Re: pic: NanoShifter
 

Quote from @FRCDesigns

Re: pic: NanoShifter
 

The easiest assembly method would probably be to cut the tube in half, assemble the innards, and put the housing back together. The reassembly of the housing could be done with plates and rivets tapped holes and screws/bolts, or welding. The second would be best for maintainability.

Re: pic: NanoShifter
 

You are correct - but part of the fun for me was to explore if it was possible to assemble with the rectangular tube intact. (BTW, if the tube is a single piece disassembly is difficult also, to get the pressed bearing out of the large gear you have to press from the other end of the shaft - this may damage the bearing.)

Re: pic: NanoShifter
 

I think this would be the best method, with standoffs located at the 4 pre-made holes on the corners of the extrusion. Of course, the thickness of the standoffs may interfere with my next topic...

The ratios do not appear to be that much different from each other with this gearbox. I presume this is due to sizing restrictions? 2 methods to deal with this are:

1.) Increase the diameter of the driven low-speed gear, which would then require slots in the housing and thin standoffs or no standoffs from the assembly method above.
2.) Decrease the diameter of the driven high-speed gear, which may require yet another custom gear for the dog gear to mate to.

Which brings up the question -- what is the smallest size 20DP gear that can be pocketed out for mating with the dog gear?