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Talk about prototyping methods and add to the prototyping kit
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@Kenneth Wiersema set the channel purpose: Talk about prototyping methods and add to the prototyping kit
Thank-you leadership for responding to the request for this channel. Here's a link to my research from the summer: https://drive.google.com/open?id=1JMOfwYPn0NeAqUxHljT5pBgLGqhw1lxW
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Here's how I recommend reviewing the PDF I shared:
- Read page 1 to understand the overall FRC prototyping principles and practices gleaned from summer research
- Skip page 2 - it's too much for starting out - I should have put it at the very end of the PDF probably. That said, for anyone who wants to dive deep, there is great information accessible from this page.
- Review page 3 about prototyping materials/kit
- Read page 4 & the rest - The rest of the PDF is a deeper dive into game pieces and intakes. Since there will ALWAYS be some form of intake, it seemed like a good area to dive into. The examples are just to get us thinking about the basic types of intakes that come up over and over again in FRC... And then think about what prototyping kit we need to be able to develop each of those types.
We have already a couple .
Here is a first draft of a prototyping kit inventory list: https://docs.google.com/spreadsheets/d/1eUymEVhlmQBUweTgs5ymC539SyQo9FS8AXR8VEnuXDw/edit?usp=sharing.
The idea is to brainstorm what a full prototyping kit (enabling very fast construction) should include, check off what we already have, and then buy the rest so we have a full kit. And then get the mechs on the team to practice using the kit so the team can hit the ground running when we hit build.
Please review this, add items to it, make comments if you like or dislike things, etc..
One plug I will make: If we truly have plenty of funds, then for a team like ours it may make sense to go the route of the Versaframe system. Here's a link: https://www.vexrobotics.com/vexpro/versaframe/all-versaframe-products
An alternative would be to buy into the system, but instead of buying the 1x2 and 1x1 predrilled, we could pre-drill our own using the xcarve and/or mills. My opinion: We should do everything / buy anything that will save us time if we can afford to do so. Time is probably our biggest constraint.
I'd like to start a thread for brainstorming the kit we would need to prototype a particular type of intake often used with medium-sized balls. Here are a couple of example pictures. What would be needed to prototype an intake like this and then test it with a couple drills? Please reply to the thread.
When I say "test it with a couple drills", I mean something like this... https://www.youtube.com/watch?v=jH4n1X1Oz7c&list=PLP0vghqKnV792cOIJK2miRWDOE5MpNaTi&index=4
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I threw this scenario out there on Chief Delphi & received a bunch of interesting responses: https://www.chiefdelphi.com/forums/showthread.php?threadid=166687
In addition to this style intake, several folks suggested using a single axle intake with mecanum wheels on the sides for centering as a simpler option.
I think it might be a great prototyping practice exercise to get a multipack of 12" beach balls, split the mechs into two groups, and have one group prototype the team 47-2002-style centering intake while the other group prototypes the simpler intake with the mecanums. Not only would it be good prototyping practice, the team would get experience with two very common, proven centering intake designs.
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Check out the intake surface area on this version! Touch It Own It... I see this is team 111 - WildStangs. I think I remember Mark T. saying he knew one of the mentors back in the day.
And here's a rendering of the different (simpler) style with mecanums on the sides for centering. (plus link to CAD: https://blog.thebluealliance.com/2017/02/01/spectrum-3847-week-4-cad-model/)
Link to Prototyping youtube playlist: https://www.youtube.com/playlist?list=PLsiEJAZgdF8LPWDAYBeQJ-EvkUpK295ra Enjoy!
Since the summer, I've been collecting links to youtube videos that related to prototyping (among other things). This past weekend, I decided to organize them into a youtube playlist, and I'm sharing it now for review by the small group in this channel. I think, for maximum impact, these videos would be watched right before the team jumps into prototyping practice and perhaps again before prototyping during build season. Here's how the playlist is organized:
- I started with the shortest videos, to spur interest and maximize exposure to different prototyping approaches to many different mechanisms
- Sprinkled in are some videos that are not specifically FRC, but they explain techniques (in particular, low-fidelity prototyping with paper/cardboard) that will be useful if we learn to use them
- Toward the end there are longer videos explaining some techniques more in-depth (including Adam Heard's excellent videos on using 2D CAD sketching as a form of prototyping)
- And finally the longest videos (a few are over an hour long) are full presentations/discussions about prototyping & related mech topics.
I really think curating sets of videos like this can enable hnew team members to do some initial learning & connecting of the dots, and then instruction by the team's leaders and mentors can be even more valuable because the new team members have a bit of a frame of reference in their brains already.
@Chris Rininger great. thanks !!!!
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254's Engineering Build Season blog has some really good details about their prototyping
There was a really insightful post to the CD thread on prototyping I shared earlier... these three phases he describes would be good to map to our process:
Consider prototyping in stages. For example:
Stage 1) quick mockup - PVC pipes and wood scraps, c-clamps and wood screws, metal scraps where needed for strength. No motors/gears/belts/chains, just manipulate parts by hand. Try multiple concepts.
Stage 2) Add quick and dirty motors/gears/belts/chains, experiment with different speeds and materials and ball compression. Refine as you go.
Stage 3) Make a more robust proto intake and hack it onto an old robot base from a previous year. Drive the mockup around chasing balls to test the pickup in a dynamic environment, try picking up balls trapped in corners, picking up a ball from a clump of balls, etc. Testing on carpet with texture and friction similiar to a tournament playing field.
Here is a link to video of 971 following this process for 2016 intake (segment from 5:17 to 6:38). https://youtu.be/fM714ulXbyI
Here is a link to 971 robot in a match - view of the intake self centering action at 0:58 and 1:10. https://youtu.be/FTdPTnLwqOY
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@Kenneth Wiersema @Cruz Strom @Jack Chapman just wanted to remind you there were two lists of things I assembled: 1) the Amazon one I believe Cruz was looking at based on our conversation on the ferry yesterday morning and 2) the Google sheets list that is based on recommended stuff for prototyping - if you did not look at the second list yet, please see the pinned post in this channel. (there’s a bit of overlap between the lists, but the second one is definitely worth checking out for ideas)
We've looked through both of the lists, and we've found most of the stuff at vex that we were already looking at getting. We'll being doing some final evaluations tomorrow.
Ok sounds good thanks!
Dana shared these on the electronics/pneumatics channel, and they're worth sharing here as well. The quality of their early intake prototypes is surprising. It seems like one of them is just their recycle rush intake remounted and the other is a copycat cuboid intake cut out on their cnc router... in any event, impressive
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Thinking about prototyping practice yesterday, here's a question to the experienced students & mentors. Yesterday, the small groups were using drills to power the 1/2-inch hex (or churro) shafts. If the desired next step was to move to a legal FRC motor and use one of the electrical team's variable speed motor controllers, what is the best (fast/effective) choice as far as power transmission from motor to one or more shafts?
- One thing that could be done is change the prototype frame to 1x2 aluminum rectangular tube that is compatible with the Vex sliding/clamping mounts for bearing & gearbox mounting. Talking about these: https://www.vexrobotics.com/217-4156.html and these: https://www.vexrobotics.com/bearingblocks.html
- Or is wood a better idea, using something like these bearing plates (e.g. two bolted together on the sides of a 2x4): http://www.andymark.com/product-p/am-3722.htm
- And then... seems like the choices are 1) sprockets & chain, 2) timing gears & belt like Vex sells, and 3) polyurethane round belt (which are easily cut/welded to size) and pulleys
To me, deciding on a standard approach for power transmission in prototyping & getting students/mentors trained up on how to do it would be super helpful come build season. Thanks!
FYI, We have the 1st two vex products.
Yep, understood - we should give them a try. Has the team used/welded polyurethane round belt before? Seems pretty flexible (size wise) and simple. Chain is most efficient mechanically I've read & most likely approach for final robot, so one could make an argument to go ahead with sprockets & chain when transitioning from drill-powered to motor-driven. My overall point was we should decide on our default power transmission approach & train a bunch of team members on it so it isn't a bottleneck skill during prototyping.
Avoid round belts when significant power needs to be transmitted. Proper tension is very important. At our prototyping skill level proper tension is hard to achieve. Unless a round belt drive is part of the finished design, use chain or cog belts.
We have a fair bit of experience with fusing polycord since we did it for the harvester. As Paul said, when we started loading them up, we saw lots of wear and slippage. We may want to learn how to splice timing belts so we can make custom lengths.
There's also link belts that seem to be gaining in popularity: https://www.harborfreight.com/vibration-free-link-belt-43771.html One plus is it looks easy to adjust length.
Timing belts can't be spliced effectively because of the way the cord works. Think trying to make a smaller radial tire from a larger diameter one. Chain is the only positive drive solution with adjustable length.
The link belts from Harbor Freight are replacements for traditional A or B section V-belts. I have not seen V-belts on any robots and would not recommend their use because of really low efficiency compared to toothed belts or chain.
Thanks for sharing your knowledge, Paul. For prototyping something fast, it seems like the toothed belts/pulleys + sliding/clamping gearbox & bearing mounts will be the way to go. But on the other hand if we can tell from the start that the end mechanism will require chain, then maybe we should go ahead & start with chain.
Here's a CAD video of a prototype-quality build using the Vex clamping gearbox/bearing stuff: https://www.youtube.com/watch?v=6D0l0bbaoM&list=PLsiEJAZgdF8LPWDAYBeQJ-EvkUpK295ra&index=64&t=0s
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I noticed the other day during robotics meeting that Ethan's prototyping team had an advantage because they had a pre-built mockup (wood and metal) of a robot chassis, one in which they could quickly mount mechanisms for testing. I think it would really help speed up prototyping if we had a couple more of these built before the season starts for each of the subteams. @Kenneth Wiersema @Jack Chapman @Ethan Rininger @Cruz Strom something to consider.
@John Sachs That is a good observation. Something to consider for this build season is that we were only able to build these once we decided on a chassis configuration. Since the space constraints vary from year to year we would have to build a test chassis after we decided on dimensions/chassis configuration. It would still probably be helpful to just have a general mounting rig rather than a specific robot chassis.
@John Sachs @Ethan Rininger I agree, it definitely helped us grasp the concept of prototyping, and though the chassis size will vary from year to year, it would definitely be a good idea to invest some time and resources into some basic structured chassis designs for future prototyping.:spartronics::clio:
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Anybody here? I'm going to try printing one of these - anyone need one for anything? There are several different items - take a look. https://www.chiefdelphi.com/t/team-5254-3d-printed-prototyping-resources/335599
The double 775 pro looks interesting, but I have a hard time seeing the advantage of some of these over the ones we already have-the versa blocks, gussets and single stage gearboxes. The bearing one might be useful though
Maybe I’ll try 2 of the bearing ones & 1 of the 2x775pro ones. Thanks for responding
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