GreyT Shooter

I wanted to start a separate thread just for the GreyT shooter and things related to it. So far some of the discussion has gone on under the WCP Product + Site Launch thread and can easily get lost there with all of the other discussion.

Questions:

  • Can we still expect these to ship sometime soon? Can you give an update on the number of Shooters sold? What is the current backlog like?
  • What additional documentation (videos, manuals, etc) can we expect?
  • How is the Falcon 500 Direct linking the motor/gearbox shaft to the wheel shaft?
  • What comes as a part of the $150 GreyT shooter? Is the camera (limelight) mount included?
  • Any problems you forsee using the Rev Throughbore Encoder on this?
  • Any other tips tricks or guidance you have for getting started with it?

Please post questions, videos, learnings, etc related to the shooter here and hopefully this thread can become a nice resource for working with the shooter.

Neat video showing off the shooter

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There might not be any other thread for the shooter, but there is a thread already for the GreyT products for 2020: GreyT 2020 Update

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I’ll answer what I can, and Rc will have to grab the rest.

  • WCP is working on some documentation as well as the yet to be posted CC which will demonstrate use.
  • The STEP file shows how the direct falcon clamp works (and this would also work for 8mm shafted motors. The idea is you use a lathe to bore or ream a tight slip fit in the end of the hex shaft for the motor shaft. You then cut (via hacksaw, bandsaw, slitting saw, etc…) a slit in the shaft that alligns with the slit in a two piece shaft collar. You can then use a 2 piece shaft collar to clamp the hex shaft very securely onto the motor shaft. If machined and assembled right, this interface has ridiculous factor of safety on torque transfer compared to full motor stall torque.
  • Any hex based encoder that fits should be able to work as long as it can handle the RPM.

As for General tricks, I’d iterate through the adjustable variables ONE at a time, and then potentially loop back for more refinement.

  1. Test different wheel types to find what seems to have the best energy transfer and/or consistency at a given compression.
  2. Adjust compression for that wheel type until you get the best energy transfer and/or consistency.
  3. Potentially adjust hood material for the above wheel type and compression.
  4. Re-iterate on 1-3 as you get each of them more locked in.

Keep clear notes! Ideally film all runs. A logical search of the variable space can yield some very insightful results.

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What types of things should we be looking for beyond just “it’s not too consistent”?

Good way to measure velocity for shooting objects is to use a speed gun.

Roy

@R.C Any update on any of these questions:

  • Can we still expect these to ship sometime soon? Can you give an update on the number of Shooters sold? What is the current backlog like?
  • What additional documentation (videos, manuals, etc) can we expect? When?
  • What comes as a part of the $150 GreyT shooter? Is the camera (limelight) mount included?
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Here’s an example of the note-taking we did when testing different wheels:Flywheel_Shooter_Tests_1_17_2020.pdf (1.1 MB)
We had someone near the ball landing zone with small strips of tape; their job was to put a piece of tape on the floor where the ball first landed. The landing zone was measured from the shooter using multiple tape measures (thus “distance plus 16”). We then used a 2019 hatch as a known scale, and placed that on the tape pieces and took a picture. The photo, with a few notes about the test setup, is enough to get comparable data between variables. Some tests, like our horizontal linear shooter, have too large of a spread to be covered by a hatch. We got the idea for the tape from this 6328 video: Ball Launcher Prototype Rev 4 but we had to use tie-dye tape for good measure

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Is there any concern with using GT2 belts in the shooter, like the belt driven version has. It is hard to get specifics on their limitations but Vex labels them good for “low load” situations. Are they good for 9000 rpm?

@R.C / @AdamHeard - Any updates on the questions above? I know you must be incredibly busy and we understand if you are behind, but we really need to know the timeline we can expect here even if it isn’t good!

All the plates are cut that include all backorders. Right now the items are being kitted & wrapped for shiipping. Between today and tomorrow all backorders should leave the door.

It just takes a bit to machine on demand/acquire all the fasteners but the wait shouldn’t be too much longer. Some items left the door yesterday and more to ship shortly.

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GT2/GT3, 3mm Pitch, is a Gates profile - information covering that profile is available in a variety of non-VEX sources, though FRC is pretty much the only market that uses/abuses them down to the 3mm pitch with something resembling real load.

Designatronics / SDP/SI carries information for the Gates GT2/GT3 profile

Index:
http://www.designatronics.com/resources/index.php?__hstc=239171548.065ce63f0346d7462ec9467e7cb1abf1.1579637890930.1579637890930.1579637890930.1&__hssc=239171548.9.1579637890931&__hsfp=1568160674

Belt Design:
https://www.sdp-si.com/D265/HTML/D265T042.html?__hstc=17737510.065ce63f0346d7462ec9467e7cb1abf1.1579637890930.1579637890930.1579637890930.1&__hssc=17737510.110.1579637890931&__hsfp=1568160674

To answer your first question, consider Section 9-7 at the above link:
SDP/SI doesn’t recommend exceeding 7500ft/min = 125 ft/s
Fortunately the surface speed of common shooters (5krpm 4" wheel) is usually closer to 80-90ft/s.

To begin to answer your second - consider that a flywheel is actually a very low torque application. With such a small reduction off the motor, the maximum sustained torque is very close to the stall torque of the motor (or lower, if geared up for a higher speed flywheel). I’m struggling to find a torque or HP rating for the smaller belts on SDP/SI right now, but I wouldn’t be that concerned about it. The closest thing I found was that minimum tension on a 9mm wide GT2 3mm standard fiber belt is about 3 pounds.

Getting into the difference of Design For Industry x Design For FRC… SDP/SI design guidelines ask for a 15x strength overhead in the belt design for transient effects to meet their design lifetime of 3,000 hours. We don’t care about that. Meanwhile, Gates doesn’t necessarily have a number for us, because they’re trying to meet 15x for 3,000 hours on any publicly posted number.

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Were there additional delays? I don’t believe ours has shipped yet, has anyone else been told theirs shipped?

Going on a week after initial estimates, and I still have several questions above that haven’t been answered. Specifically the limelight mount info and more info about additional documentation

Ours is scheduled for delivery on Friday

All the shooters / turrets are being packed. You’ll see something shortly. Main delay was hardware being shipped by the vendor in 3 different batches with one single main tracking #

Any eta for documentation? We have our lathe mentor expert here today and we want to work on the shaft.

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I’ll be posting an instructional video over the weekend.

Message me what you’re trying to do in terms of the shaft, or post here, and I can help you.

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What is the size and weight of turret and shooter in shipping?

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@AdamHeard Any update on shipping? I placed our order on the 14th.

All sourcing is handled by Wcproducts, so I can’t answer unfortunately.

I do know that RC and crew are hustling, and are producing in house to bring lead times down as much as possible.

We ordered Jan 9th and ours still hasn’t shipped!