New Offseason Build
 

Hey guys, so our team has had rough years since 2012. IN 2013 we had no robot at all and another team (I think 358) lent us a bot. In 2014 we had a drive train with no manipulator, and last year we ended with our best executed design in years but it didn't work... At all. In fact we never picked up a tote. We did actually pick up 1 single bin before the lift stopped working, but honestly that didn't make us much happier. We as a team decided a lot of things needed to change. We ripped apart our leadership system and moved from a coach(teacher) led team to a student(captain) led team. We defined sub teams a lot more strongly. We had 2 students learn Solidworks. We wrote a handbook got sponsors, and designed a new Recycle Rush Robot.


So that is the cad of the lift mech. Dont judge too hard it was my first model. The rest of the model is on my friends pc but thats the bulk of the design.

All the plates have been waterjet cut by our new sponsor and is in an impressive aircraft aluminum grade.

We have all the needed parts and we are using our 2014 drive chassi. (Sideways facing mecanums).

The lift will move up with webbing going into a single sim 27:1 winch.

Totes and bins will be picked up with a team indiana style lexan tab.

It will also be used along with a tethered ramp.

Everything just has to be cut, drilled, and assembled.

We also have some ideas for improvements. To start we want powered intakes. We already have Andymark motor brackets for rev extrusion so we should be able to build basic ones decently easy. We also want to make a recycle bin stabilizer.

Is there anything that we should add/subtract to the design. The idea of it is a really basic start so we can at least have a working robot for sponsors, parents, admins, and ourselves. We also want to have some success at the HHH off season event in November. Thanks guys

Re: New Offseason Build
 

Congratulations on taking steps to try and revamp your team! I can't comment on the execution though.
Solidworks is a fantastic tool. I highly recommend you get as many people to learn it as possible, as cadding the robot is very handy if you want any machined parts on there (from waterjet sponsors, at least).

Powered intakes, a ramp, can stabilizer, and a fast lift is all you need to do very well at this game from what I've seen. Good choices on your design!

27:1 and what diameter pulley? Try using JVN calculator to get the speed of your lift (linear mechanism tab). If you switch to 2 cims over 1, then you can gear your lift much higher, if you want to spend the extra $.
What is webbing? Like belts?

If you would like the cad of our simple pneumatic can stabilizer, PM me. It can be made on a bandsaw/drill press.

The

Re: New Offseason Build
 

It's a huge step in the right direction and I applaud your effort.
I would recommend perfecting the lift and drive, no embellishments, because it's important to take small steps as you learn. Nothing spells disappointment like over reaching. However, I would recommend designing for flexibility, so that improvements can be made once you have time or see the need to.

Do you have ME mentors with CAD experience? CAD-ing is one thing, but designing is another. Furthermore, I recommend consulting with your sponsor so that your parts are easy on them. Remember, they are giving you an expensive service for free.

Re: New Offseason Build
 

We dont know the exact diameter for the pulley yet. What is better a larger pulley or a smaller one?

We could move to a second cim as we have dozens laying around. The issue is gear boxes. We have 2 BaneBots 27:1 gearboxes laying around with cims already on them which is a large reason we just decided to use one of them.

Webbing is fabric woven as a flat strip or tube of varying width and fibres often used in place of rope. Its mainly used for fastening loads on flat bed trucks.

Also, I would love the cad for the stabilizer you can email it to me at sperkowsky@bethpageeagles.ws or just PM it to me what ever is eaisser

Re: New Offseason Build
 

We don't have any mentors with current CAD experience. Our main mentor has a lot of paper drafting experience and experience with older versions of Autocad.

Our waterjet sponsor is pretty awesome. He has a pretty crazy machine at his place from what I hear. Is there anyway to make them easier?

I have also been helping him convert .STEP files into .dwg files for cutting. Apparently thats a big problem for him, and with solidworks it only takes a minute.

Re: New Offseason Build
 

Try to minimize tool time and material usage.

A good way to minimize tool time is to cut down on the length of the tool paths.
For example, those fancy belly pans (a la 254) takes up a lot of time that could be used to cut many other parts
As in material usage, I would try to minimize the parts that have are awkward in geometry. Your sponsor would probably like to pack as many parts on a given area of sheet.

Re: New Offseason Build
 

The ratio you use is dependent upon the pulley. For example, if you spin a shaft at 10rps (600rpm) and you have a 1" diameter pulley on it, then your speed will be:
10rps * pi * 1" diameter = 31.4"/second, because you spin it 10 times per second, and each rotation is 3.14".
With a 2" pulley, the speed doubles to 62.8"/sec. This does not account for the wrapping of the belt, dynamically enlarging the pulley.

The JVN calculator will do a lot of math for you, using it could really help you.

According to JVN calc, assuming a 200lb load (accounting for friction), and a 27:1 gearbox, a 2.5" pulley and one cim gives you a loaded elevator speed of 19"/second, or 26"/sec unloaded, and draws 59 amps loaded. I assume you're not using a brake on the elevator, so the cim also has to hold the load up. If you use 2 cims, each one only draws 31 amps, which might be ok (not sure on this). Remember that your belting will add diameter, so going with a smaller 1.5" pulley or something might have to be done.
I don't know if either of those situations are permissible for cims to hold up under the constant load of suspending the stack.

That kind of belting will probably work fine strength-wise, but check that. The diameter increasing business issue is not ideal, but using a larger pulley will mean that the diameter will increase less %-wise per rotation.

Decreasing toolpaths will really help, especially for a machine like a waterjet. Using less heavy lightening patterns, like 192's 2014 gearbox, instead of heavy lightening patterns, like 254's gearboxes, will greatly help this. 192 went with 3/16" plate IIRC instead of 1/4", so they only paid a small price in weight.

Re: New Offseason Build
 

Good to see you are taking proactive steps to improve!

We estimated the maximum amount of weight we were going to lift and then decided how fast we wanted to lift that weight. I think we ended up with a 16:1 transmission with 1 CIM. To insure the transmission had enough strength to handle this load we went with a BaneBots P80 transmission. http://www.banebots.com/category/P80_CIM_STOCK.html

We also used #25 chain so we could pull the elevator down as we were concerned with the elevator getting jammed.

A nearby team picked a 12.75:1 drive transmission from AndyMark and used 2 CIM motors. If you have 2 single CIM transmissions, you might be able to use both to share the load.
Vex has a nice lookup table to compare ratio to breaking output force.
http://content.vexrobotics.com/vexpr...s-20150106.pdf

Either way you can use bungee cord or surgical tubing to counter balance the weight.

From the drawing, it was hard for me to see how the structure was going to transfer the weight from the middle of the arm to the elevator. Most teams used some angle (diagonal) support instead of relying on the strength of the joint.

For more ideas; find the top teams and go to their website to review their bot pictures or find the top local teams and go visit them.

Re: New Offseason Build
 

We are using the Banebots p80 transmission as well just the 27:! version.

Looking at other teams designs I decided the diagonal support wasn't needed and just useless weight. Most of the top teams used dual track elevators but looking at teams like 696 it doesn't seem necessary.

Re: New Offseason Build
 

What exactly is that. If many Indiana teams had it, I will know exactly what you mean when you describe it since I know just about any Indiana team. Haha

Re: New Offseason Build
 

Meaning RI3D Andymark Indiana. Looking through some more designs we are leaning slightly more towards a simple hinged plate with the middle arced in for bins.

Re: New Offseason Build
 

Update- More Cad



I still need to figure out how to model the webbing in. Then I want to CAD the wheels and back bumper even though its already built. This model does have enough to finish the bot though.

Today was our 2nd build day. Yesterday I explained the design and today we got most if not all of the cutting done one the 2x1's and 1.25x1.25's (We ordered 1x1's but it was easy enough to adapt so we didn't bother trying to replace them.

We have 27ish days so finishing this shouldnt be too hard.

Re: New Offseason Build
 

Great work so far. I wouldn't worry about modeling the webbing, but I do recommend doing a thorough 2d sketch analysis of your lift and ramp. It's much easier to edit sketches then 3d parts and assemblies. I see some potential interferences already.