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Thread: Unnamed FW crusher build diary

  1. #11
    Al_'s Avatar
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    Bits of progress on a few areas to report:

    First up, I have received and tested the speed controller for the weapon motor. I have tested it with the motor that I am fitting to the hydraulic power pack a Turnigy Aerodrive SK3 brushless and confirmed I have full forwards and reverse operation. The speed controller itself is one of the Hawk Fusion ESCs intended for RC cars. Failsafe tested and working on it too.
    IMG_20161119_124933017.jpg

    Next, thanks to some advice from Kenny, I have checked the speed of the Aerodrive compared to the motor it replaces in order to avoid pump cavitation from running it too fast. I had calculated the Aerodrive to be about 20% faster than the old motor to give me some headroom for increased flow if possible. After measuring them it turns out the Aerodrive is about 25% faster, so this means I can limit it to the same speed as the old motor by limiting the throw on the TX and still get a big increase in power, and I still have speed headroom if that’s needed/possible.

    I have had the pins for the ram and crusher arm made and test fitted together, and the parts for the front wedge and arm tip are at the water-jetters.I hope to have these soon to start mocking the parts up.

    Probably the biggest bit of progress since the last update is one of these:
    IMG_20161126_134932338.jpg
    Unfortunately this means leaving behind the comfort of a nice, warm dining room with a dining table as a workbench. The plan is to wire it up, insulate it, board it out and get some work benches in over Christmas so that bot construction can continue in there in the New Year.

    Finally, the drive for the robot is sort of modular, in that it can bolt on and off the rest of the machine. Its designed to run on a pair of Saturn 16s with the 775 motors but these are currently out of stock. By changing a couple of motor mounts I can run a pair of the Argos finest drill motors/gearboxes just to get me running around, so I have got a couple of these. I have also received one of the 2 TZ85a ESCs and successfully modified it for brushed operation. However I have a question about the drill motor/gearboxes. Ahem. How do you get the balls out? I mean a few fell out when I turned it upside down, but the rest of them wont come out even though they move freely in their holes. I have tried shaking it, I have tried sucking them out, and I have tried taping it on a hard surface (but not so hard as to damage the l/h screw)all to no avail. Any tips for doing this which don't involve taking the whole thing to bits as I can’t lock the gearboxes up with grub screws untill I remove the ball bearings.

    Cheers!

  2. #12
    I turned the gearbox so the bb's dropped down... then I bored the hole a little at the top with a slightly wider pozi screwdriver.. then turned it back the other way and they dropped out...
    you could also use the tip of a new Stanley blade.
    I need a shed too... desperately ..... and time.... lol.

  3. #13
    Al_'s Avatar
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    Thanks Matt. I had considered having a go at the top of the hole but I was weary about creating a burr on it and making the situation worse, (or at least no better!) I'll give it go.

  4. #14
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    If you don't need much power/speed on the drive, and wait for ranglebox restock for your final version anyway, the neptune-28 could be an alternative to the saturn-16.
    They're not listed in the shop, and also out of stock (ellis hasn't much time for the shop with robotwars going on, last info i got was "early next year" or something like that), but smaller and lighter.
    So for a feather that doesn't want to push or be really fast, they could be an alternative. Planning on using them, too.

    Neptune Gearbox Maße.jpg

    Just take in mind they have a 28-1 gear ratio, not the 16-1 of the saturns. Sooo... either faster motor, bigger wheels, or slower bot.

  5. #15
    Al_'s Avatar
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    I wasn't aware of the Neptune gearboxes, so that could certainly be an option if weight is an issue or I don't need as much power. Would you say they are similar to the typical drill motor/gearbox in terms of power, as I understand the Saturns are much more powerful than this? Either way I finally have the ball bearings out and the drill motor/gearboxes locked up. I can have a run around with these when I get the rest of the bits and then make a decision on final motors/gearboxes from there.

  6. #16
    The Neptunes are well build conversions of a standard batterydrill setup with 540 motor. Powerfull enough for the avarage feather.

    The Saturns with 775 motor are a lot heavier, and have enough power to do 4WD with ease.

  7. #17
    Al_'s Avatar
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    Not massive progress to report due to Christmas, the New Year and what not, but I have still got a few bits done.

    First up, the tips for the crusher arm, and the front wedge plates have been picked up from the water jet cutters. This means that for the first time I have been able to put together the chassis sides, the ram, the crushing arm with tip, and the wedge. It was good to have some assembled components in front of me for the first time.

    Next, I fixed the hydraulic pump to the mock-up with a g-clamp and took the whole lot to the local hydraulic shop where the very nice people made a set of hoses for it with integral test point. I have to give them thanks for being very patient with a hydraulics newbie on what turned out to be a pretty fiddly job for a couple of hours. I don't know if I am allowed to give out names on here but if anyone wants the name of the company for the North Notts area, feel free to PM me.

    One thing I wasn't aware of was just how much the hoses and fittings weighed, I underestimated that by a good 300g so the weight budget has just become a fair bit tighter. Unfortunately there isn't a lot I can do about the weight here so it will have to be saved elsewhere if it goes over. I have also got the shaft made that connects the new motor to the hydraulic pump. Once I get some more bolts delivered which hold this bit together, I shouldn't be too far off a first test of the weapon system.

    I have also had a couple of questions pop up which I hope you may be able to help me with:

    1) While reading the forums I came across some comments in a thread about a workaround in order to get full throw in all controller directions for the re-programmed Tz85A ESCs with the Spektrum Dx6i handset. Does anyone know if you still need to do this with the Dx6?

    2) I'm looking at getting the fuse I have to fit inline with the batteries and the rules say it is determined by the pack capacity and the burst 'C' rating of the pack. Are there any rules or good practices that people would recommend regarding the types of fuses and blow time? For example the pack I am using has a 35C constant discharge rate and a 65C burst rate for 10 seconds. It seems to me if a slow blow fuse was fitted at a rating somewhere around the 65C rate, then there might be a possibility of battery damage before the fuse blows? Or am I over thinking this and its not a problem that tends to crop up? (As it happens I'm fairly certain I'll be a long way from the burst rate discharge of the pack and probably under the constant rate at nearly all times, but I thought it was worth checking.)

    In the mean time, here is a picture of the latest progress. I must have taken it from a funny angle, it looks much taller in the picture than it actually is. Also as you can see, I'm still on the dining room table, the shed/workshop is taking longer to get sorted then I hoped.

    IMG_20161221_115922122.jpg

  8. #18
    Al_'s Avatar
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    Yay, it works!

    I got the hydraulic power pack mounted to the chassis and all the hoses connected back up, filled it with oil and went for it. At first, no movement of the weapon, but it turned out just to be air trapped in the system. After bleeding it, I have the crusher going up and down smoothly. Its turned down to about 1/3 operating pressure and 2/3 operating speed, but it actually worked, I'm well chuffed with this. I didn't have chance to turn it up any higher as I realised the pressure test gauge that I had been supplied with was only 400psi and not 400bar like it was supposed to be, and without knowing actual system pressures I didn't want to risk it. Still it had nice chew on am off-cut of 2 by 4 (closest thing I had to hand to try in it) and its still working and in one piece afterwards! There are a few lesson I have learnt:

    1) A couple of minor fluid leaks, one of which needs a new fitting, but easily fixable.

    2) Hydraulic oil gets everywhere.

    3) Get the pressure test gauge swapped and test it at higher speeds/pressures.

    4) I must hurry up and finish the shed so I can finish building the rest of the robot.
    Last edited by Al_; 16th January 2017 at 13:58.

  9. #19
    Al_'s Avatar
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    Here is a quick clip of the testing, the robot is been held on its back by a not so glamorous assistant:


  10. #20
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    Looks great!

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