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Parallax's 12V Modular Wheel and Motor Mounts - Feedback Requested!

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  • John R.John R. Posts: 1,376
    edited 2007-06-08 16:33
    Ken Gracey (Parallax) said...

    John R., it's not a blind bore, but a through-hole of 0.125" diameter, 3/4" from the end of the axle. And on the very end, there's a 1/4x20 thread. I've got several motors that offer this same shaft, which is designed into this axle. We could add a flat spot on the axle, it's no problem.


    Ken Gracey

    Ken;

    I wasn't meaning a blind bore on the shaft, but rather the "blind bore" in the wheel, with the hole for the screw to hold the hub onto the shaft.· Most "alternative" wheels or hubs I·can think of would have a through hole.· This means that when you would slide the hub/wheel/gear/sprocket on the shaft, even if you used a large washer on the screw, without a shoulder on the shaft, there is nothing to hold the hub/wheel/gear/sprocket on.

    Now setting that aside, in most of these cases, you would also have a set screw in the hub/wheel/gear/sprocket, and this could/would be used to hold things in place.

    The blind bore as you've got the prototypes is a really neat way to do things at a number of levels.· While it requires a "purpose built" hub, it also opens up some interesting possibilities.· I've even seen applications where a couple belville washers are used with a "self locking" screw to make an effective "slip clutch".


    I hope this is coming accross as "constructive discussion" and not "argumentative comments".· written communication can be a bit "cold" at times.· I see your vision, and am only trying to open up all possibilities.· (Hopefully I'll see you at the show on Tuesday!)

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    John R.
    Click here to see my Nomad Build Log
  • Ken GraceyKen Gracey Posts: 7,363
    edited 2007-06-08 17:34
    John,

    Oh yeah, I don't take this input the wrong way. That's why I sought it out in the beginning.

    Since you'll be at the show, I'll bring the whole system with me and show it to you. I hadn't planned on bringing much robotic stuff since it's a sensor show, but . . .nothing's better than talking over the "real deal" instead of forums. We can save a lot of time! Once we've got something to point at and that we can take apart we can assess options better. I might even bring an 80W power supply along.

    I got the message about the blind bore in the wheel. You're right. My wheel has a hole (for a 1/4-20 screw) and a larger 1/2" bore about 80% the way through the middle so the screw can seat the wheel onto the shaft. Got your point, and thanks for making me understand it.

    Ken Gracey
    Parallax, Inc.
  • LSBLSB Posts: 175
    edited 2007-06-10 16:00
    I work on a robotics budget of about $10 - $20 a month, so when I say here's my 2¢ worth... well, its more literal than figurative.

    I’d like to see the mounting block small enough that the motor might be used vertically as well as horizontally (and maintain “outdoor” ground clearance); also, with mounting holes on the edge of the block (even a pair of unthreaded holes, so it could slide on a pair of rods). The wheels are beautiful and will be the envy of Ferrari owners; is it possible to tap some holes in them for mounting attachments directly to the hub/ spokes (the tapped holes might be plugged with decorative caps&#8230[noparse];)[/noparse]?

    Speaking of axles… how about a lead screw attachment and (or) gears? I suspect this might be a future addition, but you’re asking now.

    As I say, my budget is small; I have to see these in 10 or 15 projects to make the cost of ownership feasible. The more versatile, the more likely I will dedicate my meager funds… especially tracks. Oh man, what I wouldn’t give for a set of tank tracks made with Parallax quality!
  • WhitWhit Posts: 4,191
    edited 2007-06-10 16:56
    Ken Gracey (Parallax) said...
    Beau,

    Robert, these are standard 6" tires from electric scooters. Tires with other styles of treads are available, too. ·There are some tires with thicker treads and knobs. Do a Google search for 6" scooter tire.

    There are some cool tires out there!


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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
  • WarrlokWarrlok Posts: 77
    edited 2007-06-10 21:59
    Beau Schwabe (Parallax) said...
    Ken,

    "I think what you're getting at is any 1/2" wheel could be slid onto the shaft and held in place with a nut, right?" - Yes ... I was searching for something that might exist, and what I am trying to describe looks very much like the tool you would use to tap a screw, only instead of three "spokes" (<- Looking at the tool on end) you would have six... I don't know maybe three would be enough.

    ·

    (Edit)

    Don't tell my wife why I'm out digging in the garage at 12:45am, but for demonstration purposes, I found a 1/4 inch tap that I have (with 4 "spokes") here are some pictures.· Pretend that the flat washer is a wheel hub, the nuts on either end would compression·lock the wheel to the shaft.· For using·a "key" to lock the wheel in place, a set screw(s) from the wheel hub could occupy the threaded "void" you see on the screw tap.·



    He might be on to somthin here ,,, then u could use bushings for diff wheels hub sounds versitile mabe just 1 slot cut in a bolt, threaded rod ,,,,,,,,,,

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    solutions are only "onramps" to the next problem



    ············································· "Brad Smith"
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  • randyazrandyaz Posts: 61
    edited 2007-06-11 07:16
    This is a great little motor·and I have several of them for various projects.· One project uses a QTI sensor for an encorder...but I'm sure you will have a more sophisticated solution.· smilewinkgrin.gif

    ·http://spooksterville.com/site/index.php?option=com_content&task=view&id=16&Itemid=25

    I think this will be an excellent product
  • Brian CarpenterBrian Carpenter Posts: 728
    edited 2007-06-11 14:42
    are you ready to sell? i am ready to buy!

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    It's Only A Stupid Question If You Have Not Googled It First!!
  • Bill ChennaultBill Chennault Posts: 1,198
    edited 2007-06-11 23:44
    Ken--

    Gee. I got in on this late. The good news is that you and everyone seem to have covered what I would want. But, let me reiterate a bit and ask a question and make a suggestion.

    Encoders are a MUST.

    How many CPR will your encoders produce?

    Ideally, Maxon motors might be the best choice. They would never quote me a price. They might quote a HUGE, CORPORATE outfit like Parallax a price, though. After Maxon, maybe Banebot. But, I wonder about the stability of their product line, even though ever since I have been buying motors from them all it has done is improved. (By the way, their high-end motors only have 128 CPR encoders.)

    In fact, the right angle feature is ultra-important. I built a right angle drive out of a Banebot gearmotor and a Dremel right angle attachment. It looks like this . . .

    RA-1.JPG

    And the guts look like this . . .

    RA-13.JPG

    Put'em on the site. I'll buy a couple.

    --Bill

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  • T0mT0m Posts: 124
    edited 2007-06-13 02:07
    I would love to bid on making those parts.

    Tom

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    http://www.youtube.com/watch?v=gbf0zaxWjvI
  • jfizerjfizer Posts: 15
    edited 2007-06-13 02:28
    I like it, so long as you keep it in aluminum I'll buy it.
  • GrievousfishGrievousfish Posts: 54
    edited 2007-06-13 06:05
    90 degree angle, yes!·yeah.gif
  • Philip GamblinPhilip Gamblin Posts: 202
    edited 2007-07-01 21:55
    From my experience there is a nice for this product type/size. I have spent much longer than i should have looking for this type of solution. What I have found arfe the trwo extremes. BOE bot sized systems or battle bot sized drive systems >$300. I have one of those motors and the shaft is a royal pain. I have found that some folks have wheels, others have motor, some have both but the integration is up to end user. Seems like you have hit the mark here. My as yet un purchased plan was a couple of kids ride on motor/wheel kits. Noisey and clunky. As far as I can tell, the price is at least fair. As you now know getting a wheel on a motor is no small task. Keep up the great work.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-07-23 23:09
    Hello everyone,

    ·· One of the guys here at Parallax (Josh) built a wooden platform one day so we could run the motors and get an idea of speed and battery life. Simple really is better sometimes. He turned it into a large wooden BOE-Bot! Using a Radio Control and a BOE (to mix the channels) we ran this around Parallax for a few days. These motors/brackets really are very nice, have great power and the motors are pretty efficient. The battery lasted over 4 hours with everyone running it about and even crashing it into walls and off curbs. The wheels (and bot) held up nicely!

    ·· Next step is to make the chassis square, put some sensors on it and essentially turn it into a large scale BOE-Bot but without a long tail end. With the platform being square it will be able to turn in place. We’ll put casters on the front and back. Essentially it won’t have a front or back. I’ll post more pictures when we get to that point. Take care.

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    Chris Savage
    Parallax Tech Support
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  • WhitWhit Posts: 4,191
    edited 2007-07-24 01:48
    Chris,

    Looks really cool. Can't wait to see more pics and maybe a video.

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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
  • bulkheadbulkhead Posts: 405
    edited 2007-07-24 03:44
    What is the Ah rating of that battery and the weight of it currently?
  • Ken GraceyKen Gracey Posts: 7,363
    edited 2007-07-24 04:25
    Bulkhead:

    That's a 7 Ah 12V battery. Probably weighs about 4-5 pounds.

    Ken Gracey
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-07-26 21:49
    Here's the requested video...Enjoy!

    http://www.youtube.com/watch?v=H1Bjb257Umg


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    Chris Savage
    Parallax Tech Support
  • WhitWhit Posts: 4,191
    edited 2007-07-27 00:38
    Great video! Shameless credit for Jeremie's truck though. wink.gif As much as I love the hybrid, there is just something about a quiet electric robot that just seems right. The noisiest thing about it seems to be the small caster wheel. Another pneumatic tire and a metal frame and it would be almost silent.

    Of couse, the only way to really decide which is neatest is to have both. tongue.gif

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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney

    Post Edited (Whit) : 7/27/2007 12:43:55 AM GMT
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-07-27 01:07
    Whit,

    You are 100% correct…The caster is a plastic/resin solid wheel and it running along the asphalt is making all the noise. Running that robot platform in Parallax on the carpeted floors it was much quieter. Of course, Joshua, who built this platform, started a new metal one today. I will wrap it tomorrow and hopefully get some video of this as we originally pictured and roaming around on its own with no RF help.

    I have all the batteries charging for tomorrow and got the remainder of the hardware after work today so I am ready to get it done tomorrow. I will post what I have tomorrow. With any luck I will have IR and PING))) sensors working tomorrow as well, although if I don’t I will post that video by Monday. We’ll see how much time there is tomorrow.

    Thanks for your interest! Ken’s wheel mounts certainly make this easy to do. Think about it…You can grab some old wood and bolt these to it and be up and running in no time! You don’t need a special machine shop or tools. Even the frame you’ll see tomorrow was made with parts from Lowe’s/Home Depot and cost under $20.00!

    P.S. - About Jeremie's truck...Every video we do out there seems to have his truck in it.· Dave A. thought we should give him credit for it!· =)

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    Chris Savage
    Parallax Tech Support
  • WhitWhit Posts: 4,191
    edited 2007-07-27 04:08
    Look forward to seeing the next video. Will the new sensors help it avoid Jeremie's truck?

    I'd love to know the difference in weight between the quick plywood chasis and the metal one. Our Lowe's/Home Depot has a pretty good selection of aluminum. Will the platform be aluminum or some other metal? It needs one of those cool tail wheels like the hybrid! (bet that would blow the $20 budget)

    Thanks to all of you for developing great products like this modular motor and wheel system.

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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney

    Post Edited (Whit) : 8/29/2007 12:07:50 PM GMT
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-07-27 18:56
    Whit,

    Yes, the new sensors will definitely help protect Jeremie’s truck. Wouldn’t want to put a scratch or dent on it! I don’t have actual weights, but the new frame is square hollow aluminum tubing and it is very light. The battery is much heavier than the frame! The great advantage to a robot of this weight/size is that it is right in between Ken’s Hybrid and the BOE-Bot for size/weight/performance. Those that have done a lot of projects on the BOE-Bot and want a bigger platform will be able to move right up to this type/size/style robot using these wheels and have the hardware and code be fully compatible with the BOE-Bot, just on a slightly larger scale. Take care.

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    Chris Savage
    Parallax Tech Support
  • WhitWhit Posts: 4,191
    edited 2007-07-27 20:14
    Chris Savage (Parallax) said...


    ·Those that have done a lot of projects on the BOE-Bot and want a bigger platform will be able to move right up to this type/size/style robot using these wheels and have the hardware and code be fully compatible with the BOE-Bot, just on a slightly larger scale. Take care.
    Chris,

    That sounds great to me. This is a much more logical step for me than the hybrid with the propeller chip (although I want to get there someday!)

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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-07-28 21:26
    Whit,

    Here are the pictures of the completed Chassis…There is supposed to be plastic on top which I didn’t get to, and then of course the sensors…Guess that will have to wait until Monday. Enjoy!

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    Chris Savage
    Parallax Tech Support
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  • WhitWhit Posts: 4,191
    edited 2007-07-29 11:44
    Chris,

    Looks great. The new motors and wheels look great. I like the new aluminum frame too. You can sure see which caster was on the previous prototype. Will the plastic be something similar to what was on the wooden chassis? Can't wait to see it running with the sensors and BOE. Will you run the BOE off of the same battery as will drive the motors? That was also a pair of HB-25s on the wooden prototype too wasn't it?

    So, if I am figuring correctly...
    • Motor and Wheels···· $200
    • Pair of HB-25s·········· $80
    • Battery w/charger······$50 - is this a good estimate?
    • Metal and misc·bits·····$20
    • BOE and Stamp········ $116

    Making the Total about······ $466· or with other sensors and gizmos $600 or so. (Of course, anyone with a BOE Bot, Ping, etc. would not have to buy everything new.)

    Does that sound about right? Note: Budget does not include money for·the awesome blue·truck in the background - right Jeremie?

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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney

    Post Edited (Whit) : 7/29/2007 12:13:16 PM GMT
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-07-30 00:11
    Whit,

    The Motors/Wheels are the same exact set that was on the wooden bot (salvaged) as are the HB-25’s. The plastic will be recycled from the wooden bot as well (try to re-use/re-purpose) what I can). The BOE will not run off the same battery as the motors…That is almost always undesirable in this type of system due to the current spikes from the motors. The BOE had a 9V battery before, but most likely this time I will use a 7.2V Ni-Cad pack.

    As for the budget I think it is a tad bit high since I would recommend having already had a BOE-Bot before building this. Everything you learn in the “Robotics with the BOE-Bot” book will carry over to this robot. All the same sensors can be used with some minor adjustments to everything. Also, the SLA battery and charger can be re-purposed from another source. For example, I have a 5Ah battery and charger from an R/C tank. But still, $50.00 is about double what I would expect to pay for one. It really depends on where you get it. I got a few Surplus and had no trouble with them.

    P.S. – As for a budget for Jeremie’s truck, I bet he’d make you a steal of a deal! =)

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    Chris Savage
    Parallax Tech Support
  • Ken GraceyKen Gracey Posts: 7,363
    edited 2007-07-30 01:45
    Hey Whit,

    I think your cost estimate is pretty darned closed, maybe even a bit low. Maybe the best way is to start with a budget and work backwards into the project, at least that's what an accountant would do. I don't know many accountants who build robots, but if they did. . .

    Chris, the new frame looks fantastic. Nice and simple design. I can't believe how fast you're building these bots lately. Wow!

    I think we should mount Jer's truck on top of a steel pole in front of the Parallax building. It's a fine piece of machinery. It represents so many good things:

    - functionality needn't be expensive
    - lots of value, fair price (like Parallax products)
    - the guy who drives it is real quality, proof that beauty is only skin deep - my dad has a comparable truck that sometimes gets parked head-to-head with Jer's truck

    I'll talk to the city on Monday about getting a permit to mount Jer's truck on a pole. Incidentally, Jer took home the Parallax stick welder about a year ago. I think he's going to be adding some panels and other structural additions to his truck. Provided he can scrape some paint off, his truck should work well with a stick welder.

    Ken Gracey
  • WhitWhit Posts: 4,191
    edited 2007-07-30 11:50
    Thanks Guys! But to build on something
    ·Mightor said... but $375 is not something I will be able to sneak past my wife, especially not for just 4 wheels [noparse]:)[/noparse]

    If you buy the parts a little at a time - the cost is harder to figure. smilewinkgrin.gif
    And sometimes it is best not to keep accurate records - at least not where they can be found.

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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney

    Post Edited (Whit) : 7/30/2007 11:57:51 AM GMT
  • MightorMightor Posts: 338
    edited 2007-07-30 12:32
    Whit said...
    Thanks Guys! But to build on something

    Mightor said... but $375 is not something I will be able to sneak past my wife, especially not for just 4 wheels [noparse]:)[/noparse]


    If you buy the parts a little at a time - the cost is harder to figure. smilewinkgrin.gif
    And sometimes it is best not to keep accurate records - at least not where they can be found.
    Hah! I wish it were that easy. My wife is great at keeping track of our expenses (thank goodness), I doubt very much I could get away with it [noparse]:)[/noparse] In all honesty, I don't think I *want* to spend that much on just robot wheels [noparse]:)[/noparse]

    Does Parallax do lay-away? *grin*

    Gr,
    Mightor

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  • WhitWhit Posts: 4,191
    edited 2007-07-30 20:28
    Chris Savage (Parallax) said...
    The BOE will not run off the same battery as the motors…That is almost always undesirable in this type of system due to the current spikes from the motors. The BOE had a 9V battery before, but most likely this time I will use a 7.2V Ni-Cad pack.
    It could run off of one battery though, couldn't it? You'd just have to have circuitry to prevent spike and noise problems, right? I would use two batteries also, but that is because I'm not that confident with the protection and noise circuitry. It is interesting to know that folks as experienced as you all might do the same. Is that because simplier is better? Or is the curcuitry need fairly complex? I was just wondering.

    Is the tubing about 1"·or 2"·square? And is the bot chassis about 12", 18" or 24"·square?·18 to 20 inches·is about what I would geuss.

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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney

    Post Edited (Whit) : 7/30/2007 9:04:32 PM GMT
  • Wade SmithWade Smith Posts: 25
    edited 2007-07-30 20:57
    Not to sound like a typical anxious consumer, but is there an estimated date of availability?
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