pic: Team 148 - 2011 - Raptor

[Aren_Hill]

Well it works for dewalt pinions, why not elsewhere, great idea

[MrForbes]

If you had the right size reamer, you could do it that way....

Press fits are a reliable way of holding gears onto shafts. Getting the fit right is sort of critical, but even if you can get it within a thousandth of an inch or so you should be ok, if it's a tight enough fit.

Drills don't work too well for this.

Also the dewalt gear is IMHO too small to fit reliably on the CIM shaft, there just isn't enough meat there. Others will disagree...

[JVN]

Originally Posted by thefro526

Wow, that's a really good idea. I can't tell from the picture, but does the pinion have the Key Shape cut into it, or do you just rely on the press fit to transfer the torque?

We rely on just the press fit to transfer the torque. It works fine -- no problems after hours of aggressive use.

[Travis Hoffman]

Originally Posted by Chris is me

What's the easiest way for Low Resource Team to get press on CIM pinions?

Bring the idea to Andy Baker's attention?

Identify potential sponsors in your area who have EDM capability, and ask nicely.

...or reach out to a team in your region who already has an EDM-capable sponsor, then see if you can barter with them. We'll machine X parts for you if you give us Y extra parts or machine Z for us in return. Bartering is fun around these here parts. Our NEOFRA teams trade materials and sponsor services all the time. Example: I submitted some lexan from 379 to our waterjet sponsor along with all our parts; in return, the RoboCats gave me their unused KOP accumulator.

[Andy Baker]

Originally Posted by Travis Hoffman

Bring the idea to Andy Baker's attention?

Huh, what, did someone mention me in the same thread as this beautiful and effective robot?

I will be sure to bug John and Greg about this in San Antonio next week.

Andy

[thefro526]

Originally Posted by JVN

We rely on just the press fit to transfer the torque. It works fine -- no problems after hours of aggressive use.

Originally Posted by Andy Baker

Huh, what, did someone mention me in the same thread as this beautiful and effective robot?

I will be sure to bug John and Greg about this in San Antonio next week.

Andy

Hmmm, I really, really hope this makes it into the AM Product line. Now that I think about it, Press Fit Pinions would make transmission assembly way easier.

[MrForbes]

Originally Posted by thefro526

Hmmm, I really, really hope this makes it into the AM Product line. Now that I think about it, Press Fit Pinions would make transmission assembly way easier.

And pinion/motor disassembly more difficult.

Not that WE've ever lost a gear due to lack of lubrication....just sayin.....but I suppose having a couple extra motors with gears pressed on would be a reasonable thing to do.

[Manoel]

Originally Posted by JVN

After receiving a number of requests in response to this post, I decided to highlight some of the subtle parts of this year's design on my blog as part of an "Inside Raptor" series.

Here is a glimpse at one of the SIMPLE subtle features that I think makes Raptor special... press-on CIM pinions:
http://blog.iamjvn.com/2011/02/insid...ion-gears.html

-John

One of those d'oh! moments... We've been wire EDM'ing all gears for our gearboxes since 2007 and that stupidly simple idea never occurred to me! In 2012 we won't be fighting with keyways, let me tell you that!

[Greg Needel]

Originally Posted by Chris is me

That's a cool idea! I wish we had the resources to try cool things like that.

What's the easiest way for Low Resource Team to get press on CIM pinions?

The easy answer is find someone with a wire edm to make them for you. You can do pressfits with a reamer on a lathe, but the issue with these is that every gear that I found that was off the shelf 11tooth already had a bore which was over the pressfit size. So you would need to find a source for some gear stock (if you find it let me know I couldn't find any. )

[Cory]

Originally Posted by Greg Needel

The easy answer is find someone with a wire edm to make them for you. You can do pressfits with a reamer on a lathe, but the issue with these is that every gear that I found that was off the shelf 11tooth already had a bore which was over the pressfit size. So you would need to find a source for some gear stock (if you find it let me know I couldn't find any. )

You can get 12T 20DP gearstock. Obviously not quite what you have, but if a team were to be satisfied with a 12T already and just wanted to press it on, that would be a solution.

[Meredith Novak]

Awesome robot, 'Ranglers. Can't wait to see it in person next week!!!

We will be up against a Raptor and a Dragon...and we look like a duck...a mighty duck...

[JVN]

Originally Posted by JVN

After receiving a number of requests in response to this post, I decided to highlight some of the subtle parts of this year's design on my blog as part of an "Inside Raptor" series.

Another in this series, discussing the one of the reasons we chose to build the design we did, and some more detail on the wrist joint:
http://blog.iamjvn.com/2011/02/insid...st-joints.html

-John

[Madison]

Originally Posted by JVN

Another in this series, discussing the one of the reasons we chose to build the design we did, and some more detail on the wrist joint:
http://blog.iamjvn.com/2011/02/insid...st-joints.html

-John

John -- thanks for taking the time to do this series of blog posts. I often wonder if the way I conceptualize and design things is "right," or if I'm off in my own corner of the world somewhere doing weird things that are crazy.

The manner y'all use to extend the upper part of your four-bar is exactly like something I'd conceptualized a few years ago after I was unhappy with the telescoping mechanism on our 2005 robot. It's awesome to see that someone else had a similar idea and even better to see it implemented so well.

[JVN]

Originally Posted by JVN

After receiving a number of requests in response to this post, I decided to highlight some of the subtle parts of this year's design on my blog as part of an "Inside Raptor" series.

Here is another in this series describing our use of aluminum plate gears this season:

http://blog.iamjvn.com/2011/02/insid...ate-gears.html

-John

[Cory]

Originally Posted by JVN

Here is another in this series describing our use of aluminum plate gears this season:

http://blog.iamjvn.com/2011/02/insid...ate-gears.html

-John

John,

I'm curious how you avoid misalignment of the teeth relative to each plate after assembly. Do you bolt both plates together and then cut the teeth? Do you use pins to align them and then clamp them with bolts? is it just "good enough" that you can bolt them together without any alignment aids?