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Thread: Unnamed FW crusher build diary

  1. #31
    Al_'s Avatar
    Member

    Update time again, and since I still can’t find any previous robots with the name of Pressure Point, I’m going with that.

    As expected it’s the little repetitive jobs that are taking all the time. First up, I have finished attaching the front wedge onto the chassis. To keep things simple, I’m holding it all together with holed and threaded square section, taking the inspiration from Pulsar and the like. This means I have been starting with plain 12mm square 6082 aluminium section, cutting to length, drilling holes in it, threading the holes, drilling matching ones on the pieces to be joined, countersinking them and so on…..And its time consuming, but all part of the fun. After a while, the front wedge was properly attached.

    Next up, the housing at the back for the drive motors. This part is designed to be modular so it’s easy to remove for repairs or to swap/upgrade drive motors at a later date. All made from HDPE, the parts have been cut out by a friend on his CNC. There are 2 of the Argos value 12v drill motor/gearboxes, each is held between 2 HDPE bulkheads to secure it, which in turn are secured to a front and back plate with barrel bolts and countersunk hex screws:
    picture 1.jpg

    The drive motor assembly then attaches to the chassis with the same holed and threaded box section the holds the rest of it together, so it was back to drilling and tapping. Here it is bolted on, however at this point I found the first main mistake that I have made. The holes for the upper fixing were off by a few mm, so I had to elongate them to make it fit. I’m not really happy with this so I’ll have to take a look at the CAD to see if I can figure out where I went wrong and then get another one cut.
    picture 2.jpg picture 3.jpg

    Next up, the base plate. I have only had time to get one fixing in it so far but it gives you an idea of how it’s going to look. The design is slightly asymmetrical, but it saves a few grams of weight, so be it. Once this is on and properly fixed, I’ll look to getting all the electrics fitted.
    picture 4.jpg

    On a final note, I have seen videos of people using taps in a battery drill to thread holes. This would speed things up for me a bit, so I was wondering, can I just put my normal tap in the drill and use it that way? Or if I do that am I likely to break something and do I need a special tap for doing it that way?
    Last edited by Al_; 13th March 2017 at 11:52.

  2. #32
    As far as I know, people usually use spiral taps for drill-tapping, I think it's because the flutes help remove the material. However I resorted to my drill with a normal hand-tap in the chuck to tap the holes for Aegis' scoop, and that was in 6082 Aluminium. As long as you keep giving it a little half-turn backwards every few revolutions, you should be ok from my experience. Just make sure you keep clearing the shavings.

  3. #33
    I quite like using WURTH taps, because they come with 3 tapers, allows you to build a thread in harder metals.

    Spiral should be fine for plastics and light alloys. Just keep the speed down.

  4. #34

  5. #35
    Al_'s Avatar
    Member

    Thanks for the advice everyone, I'll give it a go with what I've got, take it steady and see how I get on.

  6. #36
    UserFriendly
    Guest
    I love how your robot's looking Al. What hydraulic pump are you using, and where did you get it?

  7. #37
    Al_'s Avatar
    Member

    Thanks Andy. The pump assembly comes from Interfluid, at http://interfluid.co.uk I think hydra products also sell them www.hydraproducts.co.uk and I have seen them pop up on amazon occasionally too.

  8. #38
    Al_'s Avatar
    Member

    It’s time for an update that leaves the robot looking largely the same as it did before, but with lots of little bits changed internally that are hard to see.

    Continuing from last time, I have finished mounting the baseplate to the chassis. I followed the advice and tapped the holes for the fixings with the battery drill, much quicker and the tap is still in one piece, so many thanks there. After that, it all came back to bits for re-assembly, but this time with the hydraulics back in. I took the opportunity to remove a couple of sharp edges I had found on the chassis sides, and also to add a smear of grease everywhere I have moving metal on metal contact

    I found the back plate was little harder to fit this time, the reason being the force the arm puts on the chassis when it is all bolted together. I had left room in this area for some support bars, so I made one from some aluminium tube and that brought it back into line. I have also made some wheels and fitted them to the drill gearboxes. They are not the final wheels as these are too heavy, but they are the correct size so I can at lease see how the robot is sitting. At this point I was able to sneak the robot in to work for a check on the weight. We have some scales we use for weighing things we are sending out and they are the most accurate I have access to. It came out about 250g up on what I have calculated for what was assembled so for. Not a disaster and I have a couple of places I can shave some weight off if need be.

    Next job was to make a start on the electronics. Both drive ESCs sit between the chassis sides and under the ram, so hopefully will be fairly well protected there. Likewise the weapon ESC sits under the steel valve block for the weapon. The weedy wires that the drill motors come with were replaced with some 12AWG silicone insulated wire and bullet connectors added. Everything electronic has remained fairly compact but it has been at the expense of ease for running wires and connecting up cables. Battery placement has been sorted and the battery connector and removable link have been made too. That was as far as I could take things as I’m waiting on the fuse, power LED and a case for the RX to be delivered which I should have before the end of the week. Here it is as it currently looks:

    picture 10.jpgpicture 11.jpg

    After I have the parts and the electronics are finished I should be able to power it all up together on the bench for the first time. This will also give me chance to try and get the mixing for the drive working on the TX.

    Before I can stick it on the floor and drive it around I have to sort out the front wedge. I have given myself 2 ways that I can run it, but I could do with a bit of advice on the arena floors having never seen one. My first option is to take the front of the wedge down almost to a ‘blade’ and let it contact the floor and take the weight of the front part of the robot. This would get it the lowest but if I do this am I likely to keep hitting the edges of the floor panels and suffer from it as a result? My second option is a pair of skids behind the front wedge. These would instead take the weight and hold the edge of the wedge just a hair or so off the floor and with the shape of them I should be able to ride over the joins and unevenness (if there is any!?) of adjacent floor panels. Would this be a better solution from people’s experience of being in the arena? Thanks again for any advice you can offer

  9. #39
    Most robots do fine with just scraping the front wedge along the floor directly, there is a few uneven parts normally but they seem to run over them fine. Fantastic looking robot by the way!

  10. #40

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