pic: Team 4522 Team SCREAM Swerve Module

[mrwright]

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[Ryan Dognaux]

I don't have access to the CAD models at work, but great job on tackling swerve in the off-season! I'm sure it was a fun exercise for your students to go through.

Did you guys get a chance to manufacture and assemble it yet? Looking forward to seeing the real deal.

[mrwright]

We just put it through its first drive test yesterday and it seemed to handle great. Here is a quick video clip of its first run:

https://www.youtube.com/watch?v=jGTmtm8e82Y

We were able to machine all of the parts in our shop. We definitely learned a lot.

I have attached a couple of close ups of the actual modules on the chassis.

[Breakaway3937]

Those look great Michael! We found that the longest thing to manufacture are the module tubes that connect the wheel module with the stationary plate. We have used ball bearings, needle bearings, and sleeve bearings in the past. We can complete all the swerve module parts in just a few days, but the lathe gets back logged with those tubes.

How is your bearing system set up in the tube?
Do you find it takes a lot of time to manufacture those?

[mrwright]

The module tubes definitely took the longest to make and we had to get creative with them. They were also the most fun. We have a HAAS TL-1 Lathe and it was a life saver.

We bored out the ID with a boring bar and press fit bronze thrust bushings into them with an arbor press. We then parted the excess bushings off on the lathe. The thrust axle houses the bearing.

We used our mill to drill out the mounting holes. There are several operations involved but we think we can do it efficiently now if we decide to use swerve for this season.

[AdamHeard]

Looks like you can get rid of the spur reduction stage and do all your reduction w/ the timing belt.

[mrwright]

Adam,

I see that now. We could use a 24t and 60t pulley or an 18t and 48t to achieve the same reduction. We may be able to rearrange the setup which may also reduce our footprint with the mounting plate.

How would you suggest mounting the hex axle directly to the CIM motor? We don't have a keyway broach yet but that may be an option. Thoughts?

[AdamHeard]

Originally Posted by mrwright

Adam,

I see that now. We could use a 24t and 60t pulley or an 18t and 48t to achieve the same reduction. We may be able to rearrange the setup which may also reduce our footprint with the mounting plate.

How would you suggest mounting the hex axle directly to the CIM motor? We don't have a keyway broach yet but that may be an option. Thoughts?

Do you have a lathe? If so getting the reamer and broach set required for interfacing w/ CIMs is not crazy expensive.

Also, you can purchase pinions from BBman.com, sdp-si or motion industries to get a smaller pinion that what vex sells. You'd have to ream and broach afterwards.

[mrwright]

Yeah. We have lathes. I was just looking on McMaster to find the broach and bushings. We have never broached key ways before but it doesn't look too difficult.

Any concerns with mounting the .500 in Hex directly to the CIM shaft?

Here is what I think we would need to buy in order to broach correctly:

8mm reamer- http://www.mcmaster.com/#8851a23/=10a37ir
2mm keyway broach- http://www.mcmaster.com/#8805a11/=10a3730
8mm collared bushing- http://www.mcmaster.com/#8804a71/=10a36rr

[AdamHeard]

Originally Posted by mrwright

Yeah. We have lathes. I was just looking on McMaster to find the broach and bushings. We have never broached key ways before but it doesn't look too difficult.

Any concerns with mounting the .500 in Hex directly to the CIM shaft?

Here is what I think we would need to buy in order to broach correctly:

8mm reamer- http://www.mcmaster.com/#8851a23/=10a37ir
2mm keyway broach- http://www.mcmaster.com/#8805a11/=10a3730
8mm collared bushing- http://www.mcmaster.com/#8804a71/=10a36rr

Looks correct.

We've pressed 3/8 and 1/2" hex onto CIM shafts as well if you do want to stick with the hex interface.

[mrwright]

Great. Thanks! We will try this out.

[mman1506]

Originally Posted by mrwright

Adam,

I see that now. We could use a 24t and 60t pulley or an 18t and 48t to achieve the same reduction. We may be able to rearrange the setup which may also reduce our footprint with the mounting plate.

How would you suggest mounting the hex axle directly to the CIM motor? We don't have a keyway broach yet but that may be an option. Thoughts?

Vex also sells this part http://www.vexrobotics.com/vexpro/ha.../217-3255.html

[mrwright]

Originally Posted by mman1506

Vex also sells this part http://www.vexrobotics.com/vexpro/ha.../217-3255.html

Thanks for the heads up. We are actually using these on the current module. They are great little pieces of hardware. We may have to make some longer versions of them though depending on how everything lines up.

[Breakaway3937]

Originally Posted by AdamHeard

Looks correct.

We've pressed 3/8 and 1/2" hex onto CIM shafts as well if you do want to stick with the hex interface.

We did the same in our first iteration. We had no trouble pressing them on. We pressed with and without taking the motor shaft out. We even found a way to reverse the polarity of a CIM motor in the process. Lets just say the potentiometer was destroyed when the code ran!!! We had a box full of destroyed pots. When we switched to encoders on the second iteration, we could survive mistakes like that. We also run our code with only feedback loops on the turn, we don't get feedback from speed, we just go on percentage of the available voltage. We haven't noticed any issues with doing it this way.

Here is a first person video of the upgrades in code and move to encoders from Fall of 2013. This is the second iteration and unfortunately still had chains. You can hear those throughout video. We have since upgraded to belts and direct drive.

https://youtu.be/X6AjKVEwP38

The last 90 seconds is my favorite!

[AlexanderTheOK]

hmm. if you got rid of the spur gear, the belts wouldnt fit around the versaplanetary.

BUT! what if you add a SECOND CIM. If you place them side by side the reduction could be done with the belts AND it would fit around the steering motor.

The reason i had this idea is because ive seen a nearly identical vex EDR swerve