New AndyMark Shifters!

[Gabe]

Hopefully this thread doesn't exist yet...

AndyMark has new servo shifting transmission. Gotta hand it to them for eliminating the need for a pneumatic system to shift. This is awesome news!!

http://andymark.biz/products.htm

Thank you AndyMark!

[Peter Matteson]

No my question for Andy and Mark is, will there be an upgrade kit available to convert a spare gen 2 to a servo shift?

[Andy Baker]

Originally Posted by Peter Matteson

No my question for Andy and Mark is, will there be an upgrade kit available to convert a spare gen 2 to a servo shift?

Yes, we will have one ready. It's just not on the site yet. The tricky part to converting from pneumatic to servo shift would be swapping out the small "shift shaft" that is connected to the dog gear by a 3/32"x1" roll pin. If you're good at removing that roll pin, then it will be easy.

Andy B.


ps... man, Gabe, you're quick. This was put on our website at midnight last night.

[Peter Matteson]

[quote=Andy Baker]Yes, we will have one ready. It's just not on the site yet. The tricky part to converting from pneumatic to servo shift would be swapping out the small "shift shaft" that is connected to the dog gear by a 3/32"x1" roll pin. If you're good at removing that roll pin, then it will be easy.
[quote]

Shouldn't be a problem. When we built dog shifters for the first time in '04 it took a few attempts to get things right so we have experence.

I'm getting the 404 on gifts also, but I got my t-shirt already. Just another reason to drive halfway across the country to go to IRI.

[Jeremiah H]

Looks great. We're going to try to implement such a system on our custom gearboxes, so I have a couple performance questions:
-How long does it take to shift? (and what is the throw in that time period?-ours needs about 1 1/2" travel in as little time as possible)
-I don't know a lot about servos, so could a longer arm on the servo be used to decrease shift time? Would the servo be strong enough?
-How long could said arm be before the servo wouldn't have enough power to shift? Thanks. -JH

[Justin M.]

Looks great.

Two years ago we built and installed custom servo shifting gearboxes with the DeWalt motors and casings in our robot...so much torque that it bent the chassis - we had to switch out for the standard FIRST gearboxes with CIM's.

[Andy Baker]

Originally Posted by Jeremiah H

Looks great. We're going to try to implement such a system on our custom gearboxes, so I have a couple performance questions:
-How long does it take to shift? (and what is the throw in that time period?-ours needs about 1 1/2" travel in as little time as possible)
-I don't know a lot about servos, so could a longer arm on the servo be used to decrease shift time? Would the servo be strong enough?
-How long could said arm be before the servo wouldn't have enough power to shift? Thanks. -JH

The Acroname page for this product gives good specs:
60 degrees of throw in 0.19 seconds
41.6 oz-in of torque.

The servo arm has about 3/4" distance from the center of rotation of the servo out to the shift shaft. So, this translates into 55.4 ounces or ~3.46 lbs of force. This force is adequate, but it definitely does not give an immediate shift like a pneumatic cylinder does. If the arm was made longer, then the force of the servo arm would be less. I suggest not making your arm any longer.

As for shift time, the 0.19 seconds is the length of time it takes for that arm to swing 60 degrees. However, don't expect your gearbox to switch in exactly that amount of time. The first 0.1 seconds will remove the dog gear from where it was mated and then it will try to engage the other gear. Since the arm is pushing with only 3.4 lbs. of force, the engagement will not happen as quickly as it would if it was being pushed by 20 lbs from a 3/4" bore air cylinder. It may take longer (up to a full second or so) for that shifting dog gear to line up and slip into the mating dogs on the other gear.

Like any engineering decision, there are trade-offs here. For the benefit of giving up pneumatics, you are paying the price in having a lower force shifter that may take longer to engage and complete a shift.

Originally Posted by Justin M.

Looks great.

Two years ago we built and installed custom servo shifting gearboxes with the DeWalt motors and casings in our robot...so much torque that it bent the chassis - we had to switch out for the standard FIRST gearboxes with CIM's.

Yep, servo shifters have been utilized for a few years. We (team 45) had one in 1999 and then decided to publish a Servo Shifting Gearbox whitepaper in the summer of 2000.

Back then, the gearbox had to stop before the servo would shift. With the above design, the dog gear can just slam back and forth all day between the two gears, not caring what the motor speed is. Today's robot drivers have it pretty good.

Originally Posted by Billfred

Is anyone else getting a 404 for the Gifts page?

Yep... me too. grrr.


Andy B.

[David Kelly]

Originally Posted by Billfred

Is anyone else getting a 404 for the Gifts page?

Originally Posted by Andy Baker

Yep... me too. grrr.


Andy B.

Yeah, thats my fault. I'll get that fixed tonight.

[Jonathan Norris]

This is awesome.... The only reason we had pneumatics on our robot last year was for the shifting transmission. This will save those precious few pounds , especially when you are 25 pounds over weight like we were . We will definitely be grabbing a few of these in the near future.

[Travis Hoffman]

These look great, Andy.


One question - have you done any long term testing to see how the servo and the plastic components hold up during extended (and aggressive) use?

Say....running the transmission motors off a power supply for 8 hours while programming the servo to shift at 10 second intervals and seeing if everything is still in one piece and not melted/stripped/on fire the next morning? You know....fun testing like that.

8 hours operating time x (60 minutes per hour) x (60 seconds per minute) x (1 shift per 10 seconds) = 2880 shifts.

48 matches per season (worst case guess) * 20 shifts per match (again worst case guess) = 960 shifts.

I think 8 hours of continuous testing should cover it.

[M. Mellott]

Originally Posted by T. Hoffman

One question - have you done any long term testing to see how the servo and the plastic components hold up during extended use?

Don't worry, Trav--we're going to find out for ourselves. Just placed the order for a pair of 'em!!

[Conor Ryan]

Finally! I love the idea of a servo shifter, and it's great that more people will get to see why I love them now! Say good by to your heavy pneumatics! Its a 10 Dollar upgrade that is money well spent (It's marked currently for $340)

Andy and Mark, what do you see as the disadvantages and advantages of the Servo shifter over the Gen. 2 Pneumatic Shifters?


Difficult question aside, great work! I can't wait to see them on a 2007 Water Game robot! (Are the gearboxes available waterproofed yet?)

[Lil' Lavery]

Originally Posted by T. Hoffman

8 hours operating time x (60 minutes per hour) x (60 seconds per minute) x (1 shift per 10 seconds) = 2880 shifts.

48 matches per season (worst case guess) * 20 shifts per match (again worst case guess) = 960 shifts.

Your match estimate is pretty low if a team attends multiple off-season competitions.
25 played 50 matches through Regionals and Championship (but that's counting 7 Newton elim matches, and 5 Einstein matches), and attended PARC, Monty, and IRI (and still has Brunswick Eruption). They probably have played around 85-90+ matches. But they represent a very small portion of teams.
20 shifts per match is probably a little high though (116 would typically only shift around 4 or 5 times a match, at most, when we used a 2 speed). So, your estimate probably isn't that far off.

[thefro526]

the new transmissions look great and look as if they'd be easier to use

Mecanum wheels+ (4) 2 speed transmissions..........

[ChuckDickerson]

Originally Posted by Andy Baker

Yes, we will have one ready. It's just not on the site yet. The tricky part to converting from pneumatic to servo shift would be swapping out the small "shift shaft" that is connected to the dog gear by a 3/32"x1" roll pin. If you're good at removing that roll pin, then it will be easy.

Andy B.

Andy,

We have a spare Gen 1 AM Shifter sitting on the shelf. Will the "servo shift upgrade kit" work with the gen 1 shifter? If so what is in the "upgrade kit" and when will they be available for ordering?