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jwatte, nothing gives that warm&fuzzy feeling like good visibility.Quote:
seeing where you go is important :-)
While I couldn't use the ballscrews I have available for the lifting of the bucket(too slow, small pitch)
they may work out best for the dumping(only 10" travel)
looking for a 4 sec. dump time(2 sec. down, 2 sec. back up)
smooth!
https://youtu.be/ngi4qHbGw-M
with all the effort & costs that went into making the lifting frame, I'm going
to install a second prox switch on each end of travel, that shuts down drive
and turns on the brake.
or the sabertooth drive has a current limiting pot, while it can lift 500lb+
there's no reason to for snow. maybe just adjusting to a point where it
can't damage the frame would be best?
That looks awesome!
You probably should do both current limiting and safety limit switches.
Not sure about the plan A for dumping.
the gear motor I plan to use has a 180rpm output, and the sprocket on the buckets
only turns 90deg. to make it at least reasonable if things go sideways, I got 9 teeth
on the motor 45 teeth on the dump shaft, then 12 teeth on the dump shaft output to
the buckets 36 teeth sprocket, which should give it a 8 to 1 gear reduction.
Attachment 7416
Attachment 7417
Attachment 7418
hope to test the dumping setup this week(waiting on motor with brake)
Attachment 7419
Attachment 7420
Attachment 7421
Attachment 7422
Attachment 7423
to set the height of the blade I had these welded on($25.00 sweet!)
for small casters and a orange plow marker flag(should show up on camera).
Attachment 7424
I'm going to one more shaft, 12 teeth and 45 teeth get a slower
speed on the dumping setup.
5
I was able to test the dumping drive setup.
the speed is manageable but, even with a 1" shaft because of
the amount it's unsupported on each end it acts like a leaf spring(crap).
Attachment 7425
Looks quite robust! Now all you need is another foot of snow ;-)
jwatte, truth is, I'm not ready for snow.
I'm going to try plan B for the dumping setup.
I did get the new motor and tested the brake to insure
it can hold the bucket up.
heading back to office.
The way I first tested to do it the only way to adjust the chain tension was to
shim the bucket support arm.
Attachment 7427
and the motor brake had to hold all the weight that I put in
the bucket.
plan B is to replace the lower chain with an Arm off the dump output shaft,
if when the bucket is in the up position and the arm is at top dead center
the dump output shaft should hold must of the weight not the motor brake.
top dead center should be something like this
Attachment 7428
baby steps.
Attachment 7429
Attachment 7430
now with limit switches installed, and the plan B arm completed
the dump setup can be tested(sweet).
Attachment 7431
Attachment 7432
plan B for dumping worked out good enough to play with some snow.(kinda fast)
with the bucket dump all the way up, it's tilted back a small amount(to help keep snow in bucket when lifting)
I programmed a button on the controller to release the brake on the dump motor to let it tilt to the ground
by it's own weight, but because I have it at top dead center it does not float down on it's own.(crap)
https://www.youtube.com/watch?v=UKvGd1JUFG0&feature=youtu.be
From what I've learned from hand-pulled snow scoops, you may want to support up to 20 degrees backwards tilt to keep the scooped snow on the bucket. It's annoying when you try to lift things, but they fall off in front...
Anyway, I like the speed, it looks powerful and smooth!
I hope mother nature delivers some snow soon, I need to
test with snow now.
jwatte, I can only tilt back 10deg with the current bucket support arm.
and because that arm is the weakest link(1/8" tube steel), replacing it
would not hurt my feeling.
I hope to have the cameras on this weekend(back to the office)
After playing with the bucket for a short time it became clear
the switch idea isn't going to fly, too much time.
so I added a few more push buttons to the remote controller.
Attachment 7433
I like this better because I can lift or dump while the Mule is
moving. much better.
I kept the switches on the remote controller because I'm sure
I'l find a use for them sometime.
I was wondering if I could tilt the bucket back enough to keep
the snow in the bucket when lifting.
Attachment 7436
Attachment 7437
but, not ideas are good ideas.
I was thinking it would be nice to have all systems running off
one battery bank and needing only one charger, not a good idea..
if a heavy load is placed on the drives,it drives the battery voltage
below the cutoff voltage for the 110ac inverter which then drops the
wifi and cameras.(crap)
I imagine the WiFi and cameras use wall warts plugged into the 110V inverter?
I then imagine you could use a wide-input-range buck regulator (or two) to output the appropriate voltage for each of those things, without going up through 110V. You'd just need to wrap it up in some silicone tape or a Bud box with a seal or something to get it out of the weather.
Tons of cheap buck converters from Pololu or Amazon ...
jwatte, that is correct.Quote:
I imagine the WiFi and cameras use wall warts plugged into the 110V inverter?
Attachment 7438
I got a few of these last year for that purpose, but the 110vac inverter was just too
easy to implement (plug & play). I guess easy isn't always best(or workable).
some cameras need 12vdc, some need 5vdc.
because we have 6" snow coming in tonight I heated my
home work space and made the power supply changes.
removed Wifi router and cameras form the 110vac inverter.
the only thing running on 110vac is the lights.
and it tested good, under heavy load (lifting weight and driving hard only the overhead lights drop out)
Attachment 7439
Such an awesome remote drone :-)
jwatte, it's too limited by the small front casters right now, but once the back halfQuote:
Such an awesome remote drone
is complete(4 wheel drive)...then it's going to be something to behold.
even with it's current limitation i'd call it a SNOW MONSTER
current camera setup
Attachment 7440
the snow bank is made by the bucket
because I can limp along(get the job done).
the next issue needing attention is charging.
I have a few 24V chargers, 5 Amp, 7 Amp (but wanted 20 Amp).
my price range at the time of the lift build was very low.
I found a cheap 24V 10 Amp charger on amazon(under $40)
and was not shocked when it only charged at 7 Amp max.
but I do need better chargers, back to amazon......
with current chargers it takes 15Hr to charge(lost play time)
Looks cold. Better the robot than me :-)
Lead-Acid are slow-charging batteries; there's really no (safe) way around that. You can charge them with a benchtop power supply set at constant-voltage constant-current limitations if you need to, and dial up the constant-current to whatever charge rate you're comfortable risking. (Beware gassing and possible explosive spray, though!)
If you want faster charging, you're going to have to go LiPo or perhaps LiFePO. Or swappable battery banks.
jwatte, seems doableQuote:
Or swappable battery banks.
the two outside batteries could quickly changed out.
Attachment 7441
these type connectors should make the change over
plug&play,some more.
Attachment 7442
but they each weight about 100lb, so going to have to make
some kind of dolly for the batteries.
I could easily move the lights on the battery cover to some other
location to make changing simplified.
Btw, the CC/CV lead/acid cycle that works for me is:
- Set constant voltage to 14.5 V
- Set constant current to something less than the Ah rating of your battery, but in A (i e, <= 1C rate)
- Wait until the battery is drawing < 0.1 of the set A limit
- lower the CV to 13.6V for floating.
Can't win them all.
the motor I planed to use for the tilting of the bucket use an inline 250Watt.
Attachment 7457
and with it being only 250W I made it's brackets out of aluminum,
but, the first motor I used I got from ebay for $36.00 and it failed
after one month of daily use. I found a direct replacement motor on
ebay for $125.00 but, it started smoking after just a few times tilting
the bucket.(crap)
I didn't continue testing the replacement motor for fear of it causing
the sabertooth 50 to fail. (that would also suck)
So I changed the motor to a 1000Watt (same as used for the lifting)
Attachment 7458
I'm not happy with how high it sticks up so I'll look
around for a 1000W inline motor, I'v seen some four
pole inline motors use in hoverround's.
I'l also have to remake the motor bracket in steel.
It's the torque, more than the power, that matters for your bracket. Think of it this way: A motor that is stalled develops zero power (at the shaft) but develops a lot of force at the mount!
You can calculate the torque of the mounts, and compare to yield strength of the material at the given thickness/area, and if you're > 10x away, you've got plenty of margin.
Very simplistic rule-of-thumb: torque divided by distance from center of axle to center of hole equals force.
Divide by number of holes equals force per hole.
Calculate projected cross section of each hole wall -- bolt diameter times hole thickness.
Get yield strength in PSI and multiply by cross section of hole wall (in square inches) and compare to force calculated per hole.
So, let's say you have torque of 100 foot-pounds. (That's a lot, btw.)
Your shaft-to-hole distance could be about 2.5 inches. 100 footpounds divided by 2.5 inches equals about 500 pounds of force.
500 pounds of force on four holes is 125 pounds per hole.
Cross section of a 5/8 bolt in a 1/2" plate is 0.3 square inches.
0.3 square inches times 6061 yield strength of 16000 psi times 0.3 square inches means the aluminum should stand up to 4800 pounds per hole.
Your ratio is 38:1 ! (I totally guessed on all the values, though -- I may be totally off.)
Now, this is not a cerfied-engineer calculation by the book, and it's not a FEM analysis in a CAD package, so take it with a shaker of salt, but I've found this gets me to the right ballpark. It seems to me that if your aluminum bracket is anything like this calculation, you're fine.
That's actually the rough process for determining tear-out limits for fasteners in holes, but it says nothing about the rest of the bracket surviving. Also, non-ferrous materials have finite lifespans and low temperatures reduce further ductility/durability. If you have a bit of steel, you can design the part such that the cyclic loading is small enough to allow the part to have effectively 'infinite' lifespan, but non-ferrous materials do not display that property.
Sure, aluminum will fatigue and break, but, you know, they make airplanes out of it. With enough safety margin, you'll be fine :-)
Anyway, if he wants to make another bracket because he enjoys making, go for it! If he just wants to plow snow, that seems like maybe not a 100% necessary re-work, of course dependent on the specifics.
I agree that if there are narrower sections or pinch points in other places in the bracket that are more exposed, that would be a problem, too.
Yet airplanes still break apart more often than you would hope because stress fractures can be difficult to impossible to detect visually. They are detected/tracked during scheduled maintenance/inspections, but if they show up too rapidly/severely then the airframe possibly gets grounded then maybe scrapped well ahead of expected lifetime.
Only one way to settle this: Build TWO snow plowing mules, one with an aluminum bracket, and one with steel, and measure what the relevant bracket lifetimes are under equivalent workloads!
@Tommy_T, you heard @tician: Get building! :-D
My concern is not some much that the bracket
could fail, but that it could flex enough to let
the chain jump a tooth.
With a steel bracket the motor would stall before it jump a tooth.
I would like to try to make the lifting frame out of aluminum and 10" more travel
but all the brackets out of steel
breaking up ice on the streets is very hard work on the mules
also it does't give me a warm&fuzzy feeling watching the tilt motor bounce around
on the camera as it's doing it's work
Interesting!
How do you figure out where the main flex is coming from? Do you have video from the sides while it's doing it?