95 Hard at work

[JamesCH95]

Putting our shop's plasma cutter to use! Nothing quite like cutting 1/4in 6061 T6 single-pass at 110IPM.

http://i.imgur.com/QCryxlE.jpg

[mwmac]

Very nice! Shooter arms?

[Richard.Varone]

oooooooo so pretty!

[JamesCH95]

Very nice! Shooter arms?

Thanks, and nope!

[JamesCH95]

oooooooo so pretty!

I agree completely! This is the first time we've done 'trussed-out' lightening... so nice... worth the effort to CAD up.

[sdcantrell56]

What torch are you using? The cut quality looks very good

[Richard.Varone]

We did the "trussed look" on our base last year and while it looked good ( and we'll be doing it again ) it took FOREVER between having only XY CNC capabilities on our mill + breaking about 10 1/8" end mills. Pretty envious of that plasma right now :D

[JamesCH95]

What torch are you using? The cut quality looks very good

Hypertherm PowerMax 85A, running at 85A unshielded. We are fortunate in that one of our coaches is a Hypertherm engineer and can recognize when things aren't right.

Having him help out has been the difference between "man, this this sucks and does not make usable parts" and:

http://i.imgur.com/LoM9n4m.jpg

Seriously, the difference in 1/8in aluminum was +/- 0.03in tolerance if we were lucky and +/- 0.010-0.015in tolerance quite reliably. We don't have 1/4in cuts from the 'dark days'.

We still re-drill holes to clean them up though.

[JamesCH95]

We did the "trussed look" on our base last year and while it looked good ( and we'll be doing it again ) it took FOREVER between having only XY CNC capabilities on our mill + breaking about 10 1/8" end mills. Pretty envious of that plasma right now :D

Been there, done that, know that feel bro, then got REAL motivated to learn about the CNC plasma cutter. We still do fine work (precision holes, slots, etc) on our prototrak mill though.

Edit: GWizard is an absolute life changer. We do nothing without it now.

[mwmac]

Thanks, and nope!

Blooming onion catcher's mitt...?

[JamesCH95]

Blooming onion catcher's mitt...?

Halfway there... maybe 1/3 of the way there?

[The_ShamWOW88]

Looks awesome, one thing I wish our team had access to, a plasma cutter....

[Akash Rastogi]

Looks awesome, one thing I wish our team had access to, a plasma cutter....

They're relatively affordable. I think a CNC Plasma cutter is a pretty great addition to a robotics lab, especially if you're just starting out with CNC equipment.

Looks like 95 will have some sweet looking parts! Excited to see what you've come up with.

[pilum40]

What manufacturer would you recommend? I don't want to buy a low end budget (relative term right? LOL) model. I want to buy it only once but don't need aerospace or NASA grade equipment.

Any pearls would be appreciated.

Steve Miller
Coach 3355
Purple Vipers
Arlington, Texas

[JamesCH95]

What manufacturer would you recommend? I don't want to buy a low end budget (relative term right? LOL) model. I want to buy it only once but don't need aerospace or NASA grade equipment.

Any pearls would be appreciated.

Steve Miller
Coach 3355
Purple Vipers
Arlington, Texas

Hypertherm torch or bust. They are, hands down, the best torch and power supply maker out there. As for a table... we have a Nothern Plasma. It's decent, but I'd much perfer something with better driver software, like Torchmate (I personally have a torchmate CNC router).

Looks awesome, one thing I wish our team had access to, a plasma cutter....

They're relatively affordable. I think a CNC Plasma cutter is a pretty great addition to a robotics lab, especially if you're just starting out with CNC equipment.

Looks like 95 will have some sweet looking parts! Excited to see what you've come up with.

Thanks!

And yes, they're relatively inexpensive. To put it in perspective: 4'x4' CNC router of moderate quality was $7,500 new, ProtoTrak CNC knee mill was $23k new, 4'x8' plasma table with torch and power supply and computer was $25k new.

[Joe195]

Dang 95! Those parts are gorgeous!

[yash101]

Shiny :D.

That's great that you have a Plasma cutter!
That picture is what I call High Def!
That cut is also what I call High Def! Those are some quality cuts! What are those for? I bet that they are quite light while being structurally rigid!

[CalTran]

Looks like claw parts to me...

My team has access to a Torchmate, but I don't believe we've ever used it for robotics before. It goes through various states of being operational. Man it'd be nice to do cuts on it instead of our techno if we could get cuts like that out!

[JamesCH95]

Thanks for the compliments guys! We really appreciate it. The parts are for a type of mechanism that we like to call a 'carwash'. Very similar to our 2012 robot, they will deploy over the bumper and spin some fabric material to draw a ball over the bumper and into the robot: http://www.youtube.com/watch?v=9wyh1ojKQLo

Made some more parts last night, and learned a pretty good lesson after screwing up: cut rates listed 'in the book' don't always translate to real life. It was our first attempt at cutting 0.050in aluminum, book said to cut at 325IPM. That didn't turn out so well, so we cut it again at 100ipm. Both cuts used 45A fine-cut consumables running at 40-45A. These are the results:

http://i.imgur.com/JVFrkO1.jpg

http://i.imgur.com/L8Q7klK.jpg

http://i.imgur.com/BJeJGKi.jpg

This is for the belly-pan of our chassis.

[JamesCH95]

A short video of the plasma cutter in action, to give you an idea of typical cut speed.

http://www.youtube.com/watch?v=2HHVwJ_C31M

[Kevin Ray]

JamesCH95 We're in the market for a CNC plasma and are new to both. We were looking at PlasmaCam for the table, but your finished products have me sold. Our only concern is that right now no one on the team knows G code for the programming. (1) We're very proficient in solidworks and other CAD programs, will it be difficult to pick up? (2) Is the Torchmate software what you actually designed these pieces in? (3) Could we get a decent set up for about 15K?

[JamesCH95]

JamesCH95 We're in the market for a CNC plasma and are new to both. We were looking at PlasmaCam for the table, but your finished products have me sold. Our only concern is that right now no one on the team knows G code for the programming. (1) We're very proficient in solidworks and other CAD programs, will it be difficult to pick up? (2) Is the Torchmate software what you actually designed these pieces in? (3) Could we get a decent set up for about 15K?

What exactly have we sold you on?

G-Code is pretty easy to pick up as it's an extremely basic language. However, very little work is actually done in straight G-Code. About all I ever do directly in G-Code is change feed-rate commands.

1) Everything in our process is pretty easy and I was able to learn/figure it out in an hour or two. Typically this process is: design part in solidworks, make 1:1 scale drawing of part, export drawing as DXF, in TorchMate CAD turn the DXF into a torchpath with lead-ins and lead-outs, transfer to CNC control computer, convert DXF to G-Code with built-in software, edit feedrate if needed, hit go.

2) We design everything in SolidWorks, Torchmate CAD is there to make toolpaths from those designs, although it is also capable of simple design operations. There are MANY different CAM programs that can perform this function: MasterCAM, ProNest, BobCAD/CAM (what I use for my CNC router), and many others. Talk to whatever vendor you wind up buying from and see what they recommend.

3) That's a loaded question! I would strongly encourage you to talk to Hypertherm and Torchmate and see what they offer for educational institution deals. Torchmate has a number of DIY plasma cutter kits and small-format tables (2'x2', 2'x4', 4'x4') that would probably be quite budget friendly.

A Hypertherm Powermax 85 power supply will run you $3k or more at retail prices, plus consumables and a torch. You will also need to invest in either a water table or a very strong ventilation system to extract fumes from the cutting area. Do not cheap out on fume control, plasma power supply, or cutting torch, these are the most critical parts of a CNC plasma table as far as I can tell.

I'm not an expert CNC plasma table operator. Personally I have only been using them for a few months. Your best bet is to talk to Torchmate and Hypertherm to get setup. I have, however, been using manual plasma torches for a long time. This is where my strong preference for Hypertherm equipment comes from. That, and they're a US company that treats their employees REALLY well, doesn't out-source anything that I know of, and is head-quartered in the next town over from where I live.

[mplanchard]

This work is just beautiful. Well done.

With SolidWorks 2013 you can create dxf output from the Flat Pattern without setting up a drawing.

You can create *.dxf files of sheet metal flat patterns from sheet metal part documents without flattening the model or creating a drawing. This helps to export Dxf files to other applications, such as punch press or laser-cutter programming software.

Use one of these methods:

Click File > Save As and select Dxf (*.dxf) for Save as type.
Right-click Flat Pattern in the FeatureManager design tree and select Export to DXF/DWG.

Marie

[mplanchard]

This work is just beautiful. Well done.

With SolidWorks 2013 you can create dxf output from the Flat Pattern without setting up a drawing.

You can create *.dxf files of sheet metal flat patterns from sheet metal part documents without flattening the model or creating a drawing. This helps to export Dxf files to other applications, such as punch press or laser-cutter programming software.

Use one of these methods:

Click File > Save As and select Dxf (*.dxf) for Save as type.
Right-click Flat Pattern in the FeatureManager design tree and select Export to DXF/DWG.

Marie

[JamesCH95]

This work is just beautiful. Well done.

With SolidWorks 2013 you can create dxf output from the Flat Pattern without setting up a drawing.

You can create *.dxf files of sheet metal flat patterns from sheet metal part documents without flattening the model or creating a drawing. This helps to export Dxf files to other applications, such as punch press or laser-cutter programming software.

Use one of these methods:

Click File > Save As and select Dxf (*.dxf) for Save as type.
Right-click Flat Pattern in the FeatureManager design tree and select Export to DXF/DWG.

Marie

Thanks. I used that method to export a DXF last night, it worked very well. Great tip!

[Andy A.]

Our parts making continues! We had a sort of run of the mill (sorry) part to make, and I thought the setup and how we decided to make it was interesting.

Here are the parts, tube plugs being made on our prototrak knee mill:

http://i.imgur.com/lowN6gE.jpg

Those little plugs will end up welded in the ends of some tubes, and center through hole in each will be tapped. for reference, the OD is (I think) .620". We needed 24 total.

Because the OD and surface finish of the plug, and the diameter of the center hole had some fine tolerances these parts were poor candidates for plasma cutting. The plasma cutter is slick but doesn't do fine detail in thick aluminum well. Turning the parts on a lathe is the obvious choice however our lathe was busy at the time and, for a variety of reasons, wasn't a great solution for this part. That leaves the cnc mill!

Entering the program in using the prototrak 'conversational' interface was fairly easy, if a little laborious. The 24 hole array was drilled first and ran short wood screws into the wood backing plate to hold each part in place after it was trepanned out of the plate.

For those curious; the tool is a HSS 3/16 end mill with no special attributes. It ran at 2000 RPM, .1"ish doc, 6ipm with a mist coolant and was pretty happy.

The mill:

http://i.imgur.com/YQNJAx8.jpg

[JamesCH95]

Chassis plates done.

http://i.imgur.com/s09dmba.jpg

Profiled on the CNC plasma cutter, holes and slots drilled and milled on a CNC Prototrak.

Assembly starts tonight!

[Joe195]

You could probably cut out some cool stuff on those chassis plates as well

Just a thought :)

[s_forbes]

Thanks for posting your manufacturing process, it's always fun to see how different teams get things done! I'm interested to see how the tube plugs (and tubes) are worked into your design.

[BrendanB]

Nice work 95. I can see some similar features between some of our parts. Cough! :)

Mind if we send some parts to be thrown on the plasma! ;)

[mman1506]

The hypertherm looks way better than the miller we have. Are miller broke down so we are hopefully getting a hypertherm to replace it. The miller took days of tuning to do mediocre cuts.

[JamesCH95]

Nice work 95. I can see some similar features between some of our parts. Cough! :)

Mind if we send some parts to be thrown on the plasma! ;)

If you really wanted to, and brought the sheet metal over, I'm sure we could work something out. :)

[JamesCH95]

Putting my CNC router to work making the 'deck' for our robot.

Setup details: 4'x4' Torchmate Small Shop Machine router table, 100IPM X,Y travel, 10IPM plunge, 1/16in DOC, 1/8in OD 2-flute down-cut carbide router bit, 24,000rpm spindle speed. This whole setup is considerably less expensive than a plasma cutter table, and can do more materials to a better tolerance, but at a much slower rate. All of this cutting was about an hour's worth of time, not including programming or setup.

http://i.imgur.com/L0DVbcB.jpg

http://www.youtube.com/watch?v=0K8_RmQKzTY&feature=youtu.be

Apologies for the cell-phone picture and video, best I had at the time!

[JamesCH95]

That point during build season when you finally have enough parts to start assembling....

http://i.imgur.com/2eLB3hM.jpg

http://i.imgur.com/tZQKytP.jpg

http://i.imgur.com/kUhWapP.jpg

http://i.imgur.com/TglyVyk.jpg

http://i.imgur.com/fnABzmH.jpg

[BrendanB]

That point during build season when you finally have enough parts to start assembling....


Mmmmm double sided pickup? ;)

[JamesCH95]

Mmmmm double sided pickup? ;)

No no no no no... that would be crazy talk...









....yes.

[Ryan Dognaux]

Pneumatic brakes to resist pushing? I like it.

[Nebster]

Wow looks great. I hope one day my team will have the resources for a plasma cutter, it's amazing what you guys can fabricate this early in the season.

[JamesCH95]

Wow looks great. I hope one day my team will have the resources for a plasma cutter, it's amazing what you guys can fabricate this early in the season.

Thanks!

Partnering with a vocational school was the best move we've ever made. I strongly encourage other teams to search out vocational schools in their areas.

[JamesCH95]

Weekend update. Lots of assembly got done.

http://i.imgur.com/QBJsGkq.jpg

http://i.imgur.com/TpR8mWI.jpg

http://i.imgur.com/xi2S9Xt.jpg

http://i.imgur.com/gU6AhRa.jpg

http://www.youtube.com/watch?v=xjumHK5XHGo&feature=youtu.be

[Ian Curtis]

Are you worried about damage with the brake? I know 40 put a pneumatic brake on their robot in 2006 and it gave them so much trouble they took it off by Battlecry (maybe mid-season?). People just kept hitting bashing them over and over it wracked their frame since there was no give. Of course... your robot looks to have a lot less cheese holes than a Trinity robot, so maybe it isn't a problem.

[magnets]

These are seriously awesome. They remind me of some of the older 111 robots.

[JamesCH95]

Are you worried about damage with the brake? I know 40 put a pneumatic brake on their robot in 2006 and it gave them so much trouble they took it off by Battlecry (maybe mid-season?). People just kept hitting bashing them over and over it wracked their frame since there was no give. Of course... your robot looks to have a lot less cheese holes than a Trinity robot, so maybe it isn't a problem.

We are worried, a little bit. We have 0.125in chassis side plates waiting in the wings if the 0.100in side plates don't quite cut it.

What we did to address the strength concern: with the belly pan mounted the air cylinder mounts are very close to three points of lateral stability: a dead axle, the bent-up part of the belly-pan, and the horizontal part of the belly-pan. They are also not designed to lift the robot completely off of the ground. The four 3/4in cylinders can generate a maximum combined force of ~106lbf, so assuming our robot weighs at least 107lb the center wheels will still be sharing some of the load, especially sideways where the air cylinder mounts are weakest.

These are seriously awesome. They remind me of some of the older 111 robots.

Thanks!

[JamesCH95]

Slow day yesterday, a lot of planning, organizing, and tweaking rather than a lot of assembly.

Consolidated 6 compartmented boxes of electrical components into one nice, heavy-duty box:

http://i.imgur.com/L95nPgP.jpg

Started populating and mounting everything in the drive base, and even a little bit of wiring:

http://i.imgur.com/imU3kL2.jpg

[Answer42]

They are also not designed to lift the robot completely off of the ground. The four 3/4in cylinders can generate a maximum combined force of ~106lbf, so assuming our robot weighs at least 107lb the center wheels will still be sharing some of the load, especially sideways where the air cylinder mounts are weakest.

First of all, gorgeous and highly effective looking robot you have there. I have no doubt this will be a great season for you. And pneumatic brakes will definitely be an advantage to shooting this year. But, on the same subject even if your robot is not entirely off the ground, the pads will still be making solid contact with the ground. Meaning that when someone hits you with your brakes down, the robot will attempt to go in that direction and your main resisting force will be the rigidity of the (what looks like) 1/4 inch steel shaft. Even a quarter inch of movement of the whole robot would be devastating to the straightness of that shaft, particularly if the brake pads digs into the carpet and starts to twist from the horizontal. I would recommend some form of linear bearings to prevent this from happening. However to be clear, I'm no expert and this is just my 2 cents based on what I've seen from using brakes on robots.

[JamesCH95]

First of all, gorgeous and highly effective looking robot you have there. I have no doubt this will be a great season for you. And pneumatic brakes will definitely be an advantage to shooting this year. But, on the same subject even if your robot is not entirely off the ground, the pads will still be making solid contact with the ground. Meaning that when someone hits you with your brakes down, the robot will attempt to go in that direction and your main resisting force will be the rigidity of the (what looks like) 1/4 inch steel shaft. Even a quarter inch of movement of the whole robot would be devastating to the straightness of that shaft, particularly if the brake pads digs into the carpet and starts to twist from the horizontal. I would recommend some form of linear bearings to prevent this from happening. However to be clear, I'm no expert and this is just my 2 cents based on what I've seen from using brakes on robots.

We are a little nervous about this too. We plan on thoroughly testing the brakes to ensure that they will be durable enough to survive competition.

A quick analysis suggests that we have a moderate margin of safety if all 4 brakes somewhat evenly distribute the braking loads, but we don't know if the system will behave that nicely...

The (more complicated) contingency plan is to hinge brake mechanisms from the chassis side plate or the belly pan.

[JamesCH95]

Bumpers routed out in the wee hours this morning.

Details:
3/4in hardwood plywood
1/4in 2-flute up-cut carbide router bit
24k rpm spindle
180ipm feed
0.19in DOC

The simpler panels on the left took about 3min of cutting time, the more complicated parts on the right took about 14min of cutting time. Plunge speed is the main limiting factor it seems, and that will be my next set of experiments.

http://i.imgur.com/FgtZxiL.jpg

[JamesCH95]

Answer42 - We decided to get a little proactive and will be looking at installing linear bearings and/or some feature to support the brake cylinder shafts.

More to follow on that.

[JamesCH95]

Decent progress over the last two nights.

A nice little light bracket, plasma cut and then bent on a finger brake.

http://i.imgur.com/Og2TuAe.jpg

Pneumatic plumbing started.

http://i.imgur.com/e2UMomh.jpg

Using these neat clamping hinges for our access panels, which are made out of PET-G instead of polycarbonate. Much cheaper and almost as strong. PET-G panels were routed out.

http://i.imgur.com/pVYPuuz.jpg

Got some LED light strips this year. Very inexpensive, very easy to use, and prime shipping from Amazon. Cut to length, solder on leads, good to go.

http://i.imgur.com/eInuxOh.jpg

A good bit of progress filling out the guts of the robot too.

http://i.imgur.com/6Ejy6XM.jpg

[Andy A.]

It always seems like the last 10% of the robot takes half the build. Not a lot of photogenic progress in the last few meetings, but we did come to what I think is a good part to keep our brake pistons from, uh, breaking.

http://i.imgur.com/OCpVhYh.jpg

It's a small aluminum cylinder that serves as both a bearing for the shaft and a replacement for the nose nut. One end is drilled for a tight fit on the piston shaft and the other threaded for 1/2-20 to match the piston nose. When extended the unsupported shaft length is much shorter now giving it, we think, a greater (adequate?) safety margin to resist bending.

http://i.imgur.com/JEb9HtI.jpg

Most of the wiring and pneumatic plumbing is completed. Everything lights up and no smoke escaped! The new cRio has been imaged and the drive train works, validating the changes we've made from our preseason designs chain tensioning. Everything (and I do mean everything), has been labeled and for the first time ever we have some semblance of logic behind our PWM, breaker and motor assignments.

All that's left is lots of little wiring tasks and resolving the inevitable fitment issues between the two major and separately manufactured robot subassemblies.

Oh, and I guess programming. We'll probably want to budget, like, a half hour for that.

[JamesCH95]

A complete function check, from the electronics perspective, is complete. Everything talks to everything else the way it should. Tonight is an actuation check... hopefully everything works as advertised.

Added some frosted lexan backers to set off LED light in the "95" cut-outs.

http://i.imgur.com/YZ8d3Sx.jpg

We now have a nice, reliable, set of mounting points to connect the deck and drive base. We still have a good view of important lights, gauges, etc.

http://i.imgur.com/fNaJ6X1.jpg

A shot of the deck on the drive base with everything deployed.

http://i.imgur.com/TLgDV4f.jpg

[Andrew Schreiber]

Got a part number for those hinges?

[Ty Tremblay]

Got a part number for those hinges?

http://www.mcmaster.com/#piano-hinges/=qjss18

[Answer42]

Is this the magical just passing bot I've been waiting to see? Also, glad to see that your brakes are a lot sturdier now.

[JamesCH95]

Got a part number for those hinges?

The locking hinges: http://www.mcmaster.com/#1604a43/=qjtc7k (what I assume you want)

The piano hinges: http://www.mcmaster.com/#1581a561/=qjtcck

Is this the magical just passing bot I've been waiting to see? Also, glad to see that your brakes are a lot sturdier now.

Indeed. Passing, ground loading, and one heck of a catching mechanism.

Thanks, and thanks for pointing out/reminding us of the issue in the first place. It took a good bit of brainstorming and a few failed attempts (three?) to arrive at that solution. I think it'll work pretty well.

[JamesCH95]

Ah... one of the reasons I love doing FIRST. A students was shown how to do a difficult task, and then they 'get it' immediately.

These are the current-sensing chips a sophomore student soldered last night, one of their first times soldering too. Every single chip worked, none were overheated and no joints were missed. Only basic equipment was used. We can't tell the difference between the one a mentor did and the ones the student did.

http://i.imgur.com/vA6f8EK.jpg

Again, apologies for the cell phone pic.

[Caleb Sykes]

Our team is going to have a very similar design as yours. I am curious to know if you can hold more than 1 ball at a time relatively easily (for autonomous). Would you be so kind as to post results or PM me when/if you attempt to do so?

[JamesCH95]

Our team is going to have a very similar design as yours. I am curious to know if you can hold more than 1 ball at a time relatively easily (for autonomous). Would you be so kind as to post results or PM me when/if you attempt to do so?

Based on past experience with this type of mechanism it should be fairly easy. The order of operations would be: deploy rear carwash, run the rear-ward carwash in to grab a ball off the ground and pinch it against the bumper, drive forward to the low goal, run both carwashes at the same time towards the goal, pushing both balls in.

Might work, haven't tested it yet since we're being plagued by control/wiring issues. :mad:

[JamesCH95]

Here are a few videos from yesterday. We finally got everything working together: the automatic 2spd drivetrain, carwashes, and flower petals.

inkling16 - We did try various ways of carrying multiple balls at once, it seems like it will be very easy to carry 2 balls at once for autonomous. We plan on doing some more testing once the bumpers are ready.

We tried a few different ways of catching the ball, and as soon as our ball-retaining mechanism broke (snapped a few bits of string) we tried actively catching the ball, i.e. closing the blossom before the ball had a chance to bounce out. It worked pretty well.

https://www.youtube.com/watch?v=scz6LEt_D_M

https://www.youtube.com/watch?v=uL7XIHzCm_w

https://www.youtube.com/watch?v=Eak27I1cJbo

https://www.youtube.com/watch?v=kYI3Xv5LaPw

https://www.youtube.com/watch?v=nMoalLT3IpM

https://www.youtube.com/watch?v=KmG-7fNlTXA

[JamesCH95]

A little ground-loading action.

http://www.youtube.com/watch?v=1jsviL2X-TQ

[Kevin Ray]

James,
Where can you get those current sensors and how exactly do you employ them?

[JamesCH95]

Current sensor: http://www.digikey.com/product-detail/en/FHS%2040-P%2FSP600/398-1057-1-ND/1680542

Break-out-board: https://www.sparkfun.com/products/494

The current sensing chip is just a hall-effect sensor, so you only need to attach it to the wire that its measuring current. Ideally split apart for other wires as much as reasonably possible. The snag is that they must be individually calibrated since their sensitivity is dependent upon location (mainly distance from the wire).

[JamesCH95]

Attending the Week 0 event in Merrimack NH, hosted by #166, The Chop Shop. A well-run event, met a lot of great people, drove our robot a bunch, and then we broke it!

We got a basic autonomous program working (drive forward, score in low goal). When the robot was mechanically sound and setup properly it worked nearly every time.

Had a few issues with our intake rollers, one jumped a chain once and has since been fixed. Another one sucked in a spring and completely jammed up. We're going to replace the springs with rubber bands in the hopes that rubber bands will shred instead of getting tangled up! It made us really appreciate having two intakes/scoring mechanisms, we were always able to use the other if one of them went off-line.

http://i.imgur.com/3798Gqs.png

By the end of the match in the following video one of the WCP colson hub wheel bearings had shattered and the other was on its way out. The drive train chain had jumped and jammed inside the robot. With a spare bearing from 1058, PVC Pirates, we managed to get out to the field with a marginally functional drive train to lose in a brutal eliminations match.

I have no idea why the field people/human players kept tossing balls onto the field... at a few points there were 2 or 3 red balls on the field at the same time.

https://www.youtube.com/watch?v=0vojAM_yHwI

Overall a very good learning experience, got a lot of little things sorted out on the robot and got a lot of good drive practice in too. We're looking forward to sorting out the exploded wheel bearing issue soon and fine-tuning a few other things on the robot.

[Andrew Schreiber]

Attending the Week 0 event in Merrimack NH, hosted by #166, The Chop Shop. A well-run event, met a lot of great people, drove our robot a bunch, and then we broke it!

We got a basic autonomous program working (drive forward, score in low goal). When the robot was mechanically sound and setup properly it worked nearly every time.

Had a few issues with our intake rollers, one jumped a chain once and has since been fixed. Another one sucked in a spring and completely jammed up. We're going to replace the springs with rubber bands in the hopes that rubber bands will shred instead of getting tangled up! It made us really appreciate having two intakes/scoring mechanisms, we were always able to use the other if one of them went off-line.

http://i.imgur.com/3798Gqs.png

By the end of the match in the following video one of the WCP colson hub wheel bearings had shattered and the other was on its way out. The drive train chain had jumped and jammed inside the robot. With a spare bearing from 1058, PVC Pirates, we managed to get out to the field with a marginally functional drive train to lose in a brutal eliminations match.

I have no idea why the field people/human players kept tossing balls onto the field... at a few points there were 2 or 3 red balls on the field at the same time.

https://www.youtube.com/watch?v=0vojAM_yHwI

Overall a very good learning experience, got a lot of little things sorted out on the robot and got a lot of good drive practice in too. We're looking forward to sorting out the exploded wheel bearing issue soon and fine-tuning a few other things on the robot.


Attending my first NE event... yeah brutal matches. Bot looked great out there James, can't wait to see it again soon.

[JamesCH95]

Attending my first NE event... yeah brutal matches. Bot looked great out there James, can't wait to see it again soon.

Thanks Andrew! I was really impressed with your team's robot, 125 will continue to be a seriously competitive team.

[JamesCH95]

So... last night we did an autopsy on our drivetrain.

One wheel's bearings had failed completely at week 0. Its other bearing was close to failure, and two other wheel assemblies' bearings were also close to failure. :eek:

We dug up our spares (6inx1.5in Colson wheels with WCP dead-axle hubs and bearings), which have never been used, and found that the bearings in one of them were already 'cogging' or 'clicking' or 'crunching,' however you want to describe that behavior directly associated with bearings that are about to fail. Very disappointing. One of the dead-axle hubs wasn't even tapped!

After popping some of the bearings out we found that the lips on some of the WCP hubs were peened in asymmetrically, presumably to retain the bearings. We had a few extra bearings so I tried pressing them into the hubs after trying to clean them up a bit. In one hub the bearing actually cracked as I pressed it in!

Whatever was going on, WCP had some serious quality control issues with their dead-axle colson wheel hubs and bearings. I've never been disappointed with any OTS FRC hardware until now... and very frustrating to have it happen right at the end of build.

New bearings are on the way from McMaster and AndyMark, hopefully we can get something together before midnight tonight, even if we have to re-bore the colson wheel hubs.

[Joe195]

So... last night we did an autopsy on our drivetrain.

One wheel's bearings had failed completely at week 0. Its other bearing was close to failure, and two other wheel assemblies' bearings were also close to failure. :eek:

We dug up our spares (6inx1.5in Colson wheels with WCP dead-axle hubs and bearings), which have never been used, and found that the bearings in one of them were already 'cogging' or 'clicking' or 'crunching,' however you want to describe that behavior directly associated with bearings that are about to fail. Very disappointing. One of the dead-axle hubs wasn't even tapped!

After popping some of the bearings out we found that the lips on some of the WCP hubs were peened in asymmetrically, presumably to retain the bearings. We had a few extra bearings so I tried pressing them into the hubs after trying to clean them up a bit. In one hub the bearing actually cracked as I pressed it in!

Whatever was going on, WCP had some serious quality control issues with their dead-axle colson wheel hubs and bearings. I've never been disappointed with any OTS FRC hardware until now... and very frustrating to have it happen right at the end of build.

New bearings are on the way from McMaster and AndyMark, hopefully we can get something together before midnight tonight, even if we have to re-bore the colson wheel hubs.

Sorry to hear James. Hope your new hardware works better. Good luck.

[JamesCH95]

Sorry to hear James. Hope your new hardware works better. Good luck.

Thanks.

Well... nothing is ever easy! The replacement bearings from McMaster had a lip on them that we had to take off with a surface grinder. On the plus side surface grinders are fairly amusing to use...

http://i.imgur.com/vocgphe.jpg

After taking apart the remainder of the WCP hubs we found evidence that some of the bearings had been pressed in at an angle, likely contributing to the premature failures we had. We reamed out all of the hubs to 0.875in to give the replacement bearings a light press fit/slip fit, which worked really well.

On that front: WCP has gotten in touch with me about the failures we saw and seem genuinely concerned about what's happened and intend to figure out why and make it right. It's nice to have see a company go out of their way to stand behind their products. I would, and probably will, buy WCP products in the future despite this frustrating experience given how good their customer service has been thus far.

Back on track... with fresh bearings we reassembled the drive train. Runs like absolute butter now, and the robot seems to be faster and to track straighter. We can't even hear the chain anymore. We also replace the coil springs that keep some string under control with rubber bands. The rubber bands get shredded if they get sucked into the carwash, instead of tangling up the carwash completely like the coil springs did (see earlier post).

http://i.imgur.com/T6jPtwi.jpg

We spent a bit of time tweaking and rebuilding the carwash mechanisms. Most notably we replace the mini-CIMs with RS775-18 motors and CIM-U-LATOR gearboxes. This drops about 1lb of mass from each assembly which helps deploy/retract times, makes the robot less tippy, and gets us a more powerful motor with an output shaft that can deal with side-loading well.

http://i.imgur.com/lHpB1LM.jpg

We also added some ultrasonic sensors to the deck that allow us to see an incoming ball and automatically catch it. We may need some additional tweaks to get it running smoothly, but have cleanly demonstrated that it works.

At 11:11 we bagged the robot. It was fully-functional, had all of its mechanisms in place, had been driven in ~10 matches and lots of drive practice, had a working autonomous move, and was 10lbs under weight. Man did that feel good after the roller-coaster that was our week-0 experience, and a LOT better than last year.


I hope everyone liked reading our 'build thread.' If enough of you did then I think we'll do another build thread next year. I know its not as tantalizing as a bunch of teaser pics/videos, or as dramatic as some of the well-done reveal videos, I just hope it was a little helpful and a little inspirational to see a team's whole manufacturing process. Maybe next year we'll include the prototyping and design processes.

What say you, CD?

[nxtmonkeys]

Looks complicated.

[Andy A.]

Looks complicated.


Complexity is a relative thing. In many ways this is the simplest robot our team has made in many years. It certainly doesn't posses any particularly intricate mechanisms (beyond the purchased shifting gearboxes); just simple chains, sprockets and pneumatics.

It terms of design, fabrication, maintenance and use it's pretty straightforward. Everything is just mirrored left/right and front/back, and the most complex mechanisms were iterations of things we've done in previous seasons or during the fall. It might look more complicated than it really is because we have two of everything.

[nxtmonkeys]

What I meant was that it looks complicated. I have found that making something that you understand [I]seem[I] more complicated, then you seem smarter. It works almost every time. It's awesome.





Good luck everyone!

[JamesCH95]

No trickery here. Are you implying that we're trying to look smart by making our robot appear more complicated than it is?

[Ian Curtis]

I love how well labeled your equipment is. We will definitely be doing that!

[nxtmonkeys]

No trickery here. Are you implying that we're trying to look smart by making our robot appear more complicated than it is?

No, I'm saying that you ARE smart. The robot looks complicated to me because I didn't make the bot. To me, my robot looks simple. to other people, my robot may seem overwhelmingly complex. No offense intended in my earlier posts.

[JamesCH95]

I love how well labeled your equipment is. We will definitely be doing that!

Thanks! At first it seemed excessive... and then when we went to debug things and assign all of the controllers in code and it all paid off. We will be just as thorough next year.

[JamesCH95]

Our carwash mounts have been beat to heck given the game play. Fortunately we had anticipated this situation, and made stronger kitty-based replacements.

http://i.imgur.com/YlHrxe8.jpg

Though even the kitties weren't enough to stop us from a major failure in our deck after playing some particularly aggressive defense.

http://i.imgur.com/ihi302I.jpg

We're all patched up and running reliably, but it sure has been brutal out there!

The robot is playing out about as we thought it would: we win pretty much any match when we're paired with a shooter, and have gotten a lot of truss, catch, and assist points in those matches. Matches were we have 1 working alliance partner who can only ground-load aren't turning out so well. Thus far we haven't had any matches will all ground-loading robots.

[JamesCH95]

We had a very fun time at the GSDE, with a disappointing run in eliminations.

As posted we had some carnage and a few things that broke and/or needed more fine tuning, but nothing really catastrophic (certainly nothing like Week 0!) We were really glad to have two independent intake mechanisms; in a few matches we lost on a chain on one and were still able to score with the other. After reinforcing the deck that was damaged (see previous post) our intake mechanism geometry changed in a way that we had not anticipated. This lead to some matches with awkward ball pickup, losing possession of the ball, and missed 2-ball auto programs, but we were able to apply a good fix and haven't had issues since. We had some problems with our brake pads being torn up and dragging on the ground that we fixed too. We also had a few hiccoughs with our 2-ball and 1-ball auto moves, but have worked through those issues and had them running reliably by the end of the event. There are some parts that require revision before our next event, but nothing too serious.

From a strategic point of view the robot played very much how we expected: when we had a solid group of alliance partners we scored very high and usually won. When we were grouped with non-functional, non-cooperative, or non-present robots our scoring was atrocious because we rely on assists and trussing/catches to generate points. We wound up with a 7-5 record after qualifications, with an event-best of 320 assist points. We were the highest-seeded non-shooting robot, and if we had won just one more match we likely would have seeded second (and at least one of our qualification matches was lost due to penalty points we didn't incur) but that's how it goes some times!

This was, I think, our highest scoring match. Twice we scored 1pt goals after catching a truss to make a triple assist. It shows how quickly we can convert a caught truss shot and assists into points and how quickly we can get into position for a catch.

https://www.youtube.com/watch?v=Zq_LmY7Npb0

I think all of our match videos are posted on the same YouTube channel if you're interested. The good, the bad, and the ugly.

I am really satisfied with how well our drivers have learned to use both sides of a two-pickup robot. It has saved a ton of time because we don't have to reorient a robot, and given us a lot of options in getting around defenders.

We were selected by team 2648 in the first round, team 885 joined our alliance in the second round. In the first quarter-finals match we were dead in the water. The explanation we got from the FTA was that the FMS system had gotten an erroneous reading from one of our joysticks and had locked them out. Apparently we should have pressed F1 to reset them... I wish we had known that, or they had come over during the match to see what was wrong! 2648 and 885 did a heck of a job getting that match to within 11pts as 2V3. In the second match we were operational, cleaned up a missed auto ball and tried to catch some truss shots, but it just wasn't working out for our alliance. We played some good far-field defense, and even transitioned to passing between 2684 and 885 when we needed to. In the end we couldn't quite pull it off, but we certainly gave it a good go. We would like to thank 2648 and 885 for playing with us in the eliminations!

Here is a video of our second quarter-final match. Around 3:40 you can see our robot rock back and our bumper land on top of 1517's bumper. That was called as a 50pt technical foul for deliberate or damaging contact inside the frame perimeter of another robot. For the record, it was unintentional and (call me crazy) seemed quite inconsequential.

https://www.youtube.com/watch?v=uvaok5gPPpQ

We are looking forward to competing at the Hartford CT District Event at the end of March. Good luck to all teams!

[JamesCH95]

Our 3-ball autonomous... :yikes:

https://www.youtube.com/watch?v=MbTj9oifrGA

[JamesCH95]

We had a good time at HCTDE. We played some really good matches, scored a few upsets, and were really able to flex the capabilities of our robot.

We pulled off a 3-ball auto move, twice. The only two times that program has ever been run! We didn't have time to test it before we used it. It helped us win one upset match and very nearly win another upset match.

I think we concretely demonstrated the viability of a good catching robot, but also showed how important a good shooter is in that effort. In one of our replay matches 177 was able to truss to us 2-3 times with us under defense from 1-2 robots, from blue zone to red zone no less! It was really nice to play with 177 for the first time in years.

We ran our quarter-final rounds to 3, and only lost the last match by 10 points. Very close, and a bit disappointing, but I know each team on our alliance drove their hearts out. An unfortunate combination of bad luck and a strong opposing alliance kept us from advancing. Thank you 3464 for picking us! And Thank you 178 for rounding out our alliance! You guys were two of the best drive team's we've worked with.

We did win the Xerox Creativity Award for our braking system and catching mechanism. This was most gratifying, and our first technical award since 2008. Team 571, Paragon, also gave us an award from their team for most creative robot design. I'm not sure which one means more to us: the official FRC award or Paragon's!

Unfortunately it's looking like we won't have the points to qualify for the District Championships. We will probably be doing a couple post-season events though.

Here are some pictures from the Hartford event and a link to our team's youtube account where match videos, including robot and drive team GoPro footage, will be posted sometime later this week.

https://www.flickr.com/photos/supatodd/13541869633/in/set-72157643219020225
(I think this is the best shot of our robot all season!)

https://www.flickr.com/photos/supatodd/13541811053/in/set-72157643219020225
https://www.flickr.com/photos/supatodd/13541701235/in/set-72157643219020225
https://www.flickr.com/photos/supatodd/13542020484/in/set-72157643219020225
https://www.flickr.com/photos/supatodd/13541673845/in/set-72157643219020225
https://www.flickr.com/photos/supatodd/13541754935/in/set-72157643219020225

95's Youtube Channel (https://www.youtube.com/channel/UCRXcfSYmEfn7XpdtmPtiFZA)

Thank you everyone for reading, commenting, and following along this season. I know it made a big difference to our students to hear all of your positive comments and feedback throughout build and at each district event.

[Nathan Streeter]

I was very bummed to see you guys go out in the quarterfinals again... your alliances have gotten some tough luck in terms of opponents and partners braking!

I'm personally hoping the DCMP invites will somehow dip down to 51 points! If not, I'm sure we'll see you at various off-season events! :-)