Next large robot

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  • DiverBobDiverBob Posts: 752
    edited 2013-07-04 - 21:26:54
    While putting together the lower leg assemblies I noticed an excessive amount of space on one of the spacers. I determined that they were supposed to be 1.990 inches long but I had cut them 1.900 instead, 0.090 short which translates to 0.045 on either side. So back to the lathe and fabricate 5 new spaces. I'll anodize those in the morning. Otherwise things are going fairly well. It's important to make sure all the leg pieces are exactly parallel with each other otherwise there will be rubbing which will cause a lot of problems.

    Bob
  • photomankcphotomankc Posts: 929
    edited 2013-07-05 - 06:54:30
    Grins or grimace, upside down numbers are now part of the tale. My current project has seen a couple of new parts due to fabrication mistakes, but the worst mistake I ever made was 15 years ago on a wood-working project. I was making a two-drawer lo-boy dresser. The front legs had 5 mortises and a taper. The outside edges had to be rounded over on the router table, so I picked one up and promptly rounded over the wrong edge. That was a 10-hour mistake. I hope not to set a new mistake record in the future!

    Back in the early days of manual milling when I knew enough to be dangerous, I had a part that was fairly complex, tight tolerance bore, slotting, slitting cut needed, angles, rounded pocket, ect. Somewhere over 1.5 weeks worth of evenings were invested. One mistake on the rotary table and poof it was destroyed in a way that was not possible to compensate for and was scrap. I had to go take a drive because I want to "Hulk SMASH" the whole shop that night. I used it for a time as a reminder to not decide to skip double and triple checking because things were going well so far.

    One of the biggest butt-pucker projects I made it through though was turning a solid 7" round of hot rolled steel into a chuck adapter for a new Bison set-true chuck. That was days of turning and setup just to get the exterior roughed out not to mention it was not a cheap hunk of steel. The internal threading and spindle register bore were the hardest parts and they had to be done last more or less. I managed to get it right though and was real pleased with the outcome. I guess a level of confidence helps. The more nervous I get about screwing it up it seems the more likely I am to screw it up.

    For some reason I mess up more on the mill still than the lathe. I think because the lathe is often more straight-forward. Most times on the CNC mill it's a forgotten offset that ruins my afternoon.
  • DiverBobDiverBob Posts: 752
    edited 2013-07-05 - 07:53:22
    I can definitely agree with you there! I have a large drawer full of oops parts! I always assume the first one or two milling passes will be wrong someway, although with experience this seems to occur less frequently. I always order 10% more stock than I need, if I get it right I now have extra for other projects.

    I found that the dimensions are correct on my drawings for the part but I also have a 1.900 spacer and got it into my head that I needed 12 that size and not 6 and didn't reference the drawing like I should have. The extras will go into the scrap bin with the others, I may be able to repurpose them into another part someday.

    Didn't get anything done yesterday so I need to make up for it today. Starting up the anodizing line and anodizing the 5 new spacers. Following that I will be cutting the gear reduction shafts. I would like to get all six legs put together this weekend and start working on attaching them to hexapod body next week. It should start looking like a hexapod soon! Wiring each leg will take time also.

    Sorry I don't have any photos to share, we misplaced the special battery charger for the camera and the battery was dead. The charger was finally located and battery charged so fresh photos will be coming. I've been photographing most of the build process and have hundreds of pictures and videos that don't make it here. I don't want to bore people with too much detail!

    The additional leg impact sensor strips are on back order so I'm going to skip installing those since I only have 3 right now.

    Still a lot to do in a short time before the Expo. Hope to see some of you there. They just opened up pre-registration so I need to get over there and sign up.

    Bob
  • DiverBobDiverBob Posts: 752
    edited 2013-07-08 - 17:28:10
    4 of the 6 legs are put together now. I need to order 12, 1 inch shoulder bolts for one location, the 3/4 bolts are just a tad too short. But otherwise everything is going together well. It does take time to assemble each leg to ensure all the parts are parallel so I'll need a few more days to finish the remaining 2 legs between work, exercising and Honey-Do list activities. Here are some photos of the parts build and leg build.
    attachment.php?attachmentid=102688&stc=1&thumb=1&d=1373328636
    These are the 5 'new' 1.990 spacers prior to anodizing
    attachment.php?attachmentid=102691&stc=1&thumb=1&d=1373328723
    This shows all the various spacers waiting to be installed, the missing spacers are already installed
    attachment.php?attachmentid=102693&stc=1&thumb=1&d=1373328781
    These are the anodized 'knees' for the leg, numbered 1 through 6.
    attachment.php?attachmentid=102690&stc=1&thumb=1&d=1373328694
    Leg mounting blocks partially assembled
    attachment.php?attachmentid=102689&stc=1&thumb=1&d=1373328663
    Lower leg assemblies ready to be mounted in knees
    attachment.php?attachmentid=102685&stc=1&thumb=1&d=1370825843
    An assembled knee - minus the leg down switch block and impact sensor
    attachment.php?attachmentid=102687&stc=1&thumb=1&d=1370825769attachment.php?attachmentid=102692&stc=1&thumb=1&d=1373328754
    Stacks of parts ready for assembly. The right photo are lift motor connection assemblies
    attachment.php?attachmentid=102686&stc=1&thumb=1&d=1370825731
    This is leg #5 being assembled.

    I took a day off to go diving a shipwreck in 155 ft of water in Lake Michigan with 5 other divers. It was a good break from the shop
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  • TtailspinTtailspin Posts: 1,326
    edited 2013-07-08 - 18:26:55
    Go Bob Go... :)

    I can't wait to see the trailer you build to haul this thing to the Expo...

    Oh wait, what am I saying? I bet you already have a trailer built. :)

    Awesome work, Thanks for sharing.


    -Tommy
  • DiverBobDiverBob Posts: 752
    edited 2013-07-14 - 18:13:51
    All six legs are put together and I have one mounted on the body! I created 3 spacers for each leg to position the leg thrust bearings correctly. That went pretty quickly in the new lathe. The lift motors are not installed yet, because the location where the wire comes out of the motor housing is in a different location than the original motor, it rubs against the strut on that side. So I need to come up with a different way to route the wires by drilling a new hole in a different location. As I was typing this I thought of another option, carefully cutting off the metal casting protrusion holding the plastic piece the wire comes through and putting a small rubber grommet in its place. Hmmmm, Need to check that out....
    IMG_3846.jpg
    IMG_3847.jpg
    IMG_3848.jpg
    IMG_3849.jpg


    I'm working on the remaining 5 gear reduction units. There is a steel shaft that has press fit tolerances for the gears to be created and the gear motor output shafts have to be machined. This requires dis-assembly of the gear motor and then carefully mounting the output shaft in the lathe. The shaft is then turned down to 0.2505 diameter for a press fit along the main shaft and 0.2495 diameter for where it passes through the bronze bushings.

    I have to see how much I can get done this week, my schedule is pretty full plus getting ready for a big dive next Sunday.

    Bob
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  • photomankcphotomankc Posts: 929
    edited 2013-07-15 - 21:29:01
    Man that thing is huge! If there is a Sarah Conner in your area of operation it really is imperative that you send it to visit her when it's working.
  • DiverBobDiverBob Posts: 752
    edited 2013-07-16 - 17:58:24
    photomankc wrote: »
    Man that thing is huge! If there is a Sarah Conner in your area of operation it really is imperative that you send it to visit her when it's working.
    It is a little large! Wait until I get all 6 legs mounted, then it will be heavy too. Just don't let it step on your toe when it starts walking!

    Time to head to the basement for a bit, got some gear shafts to turn on the lathe. I tried to use the new lathe last night but I haven't aligned the head yet so I get a taper when turning the shaft. That messes up press fitting the gears so its back to the small lathe until I finish aligning the headstock.

    Bob
  • vanmunchvanmunch Posts: 567
    edited 2013-07-16 - 19:30:04
    DiverBob wrote: »
    All six legs are put together and I have one mounted on the body! I created 3 spacers for each leg to position the leg thrust bearings correctly. That went pretty quickly in the new lathe. The lift motors are not installed yet, because the location where the wire comes out of the motor housing is in a different location than the original motor, it rubs against the strut on that side. So I need to come up with a different way to route the wires by drilling a new hole in a different location. As I was typing this I thought of another option, carefully cutting off the metal casting protrusion holding the plastic piece the wire comes through and putting a small rubber grommet in its place. Hmmmm, Need to check that out....
    IMG_3846.jpg
    IMG_3847.jpg
    IMG_3848.jpg
    IMG_3849.jpg




    I'm working on the remaining 5 gear reduction units. There is a steel shaft that has press fit tolerances for the gears to be created and the gear motor output shafts have to be machined. This requires dis-assembly of the gear motor and then carefully mounting the output shaft in the lathe. The shaft is then turned down to 0.2505 diameter for a press fit along the main shaft and 0.2495 diameter for where it passes through the bronze bushings.

    I have to see how much I can get done this week, my schedule is pretty full plus getting ready for a big dive next Sunday.

    Bob

    Looking good. It will be worth a trip to what ever expo you bring it too. :) BTW I see the McMaster-Carr bag your secret sauce is out!:)
    My wife is very, very understanding

    Prospero: Robot Farmer
    http://www.youtube.com/watch?v=ACtihXjq2B0
    www.DorhoutRD.com
  • DiverBobDiverBob Posts: 752
    edited 2013-07-17 - 04:30:57
    vanmunch wrote: »
    Looking good. It will be worth a trip to what ever expo you bring it too. :) BTW I see the McMaster-Carr bag your secret sauce is out!:)
    Yes, McMaster-Carr is a hidden resource that has received a lot of my cash! Got another box of fasteners last night, only $87 worth of shoulder bolts for finishing up installation of the lift motors! Those little bolts are pricy and I'm using a lot of them.

    Didn't get a lot done last night, worked on a gear reduction shaft and almost finished it. It needs a final sanding to size and polishing before I can press fit the gears tonight. The wife is off on a girls night out so I'll have more time to play. The plan is to get everything ready to mount the next leg on the body ready to go
  • DiverBobDiverBob Posts: 752
    edited 2013-07-21 - 18:30:41
    Managed to destroy the gear shaft I built, just a bit oversized and I thought I could 'make' it fit anyway. Ended up mushrooming the ends and bending the shaft and a little damage to the gear. Not a good idea for something that is supposed to turn! So back to the lathe and made another one, this time to the correct dimensions. It was amazing how well the gears pressed into place this time. I also turned down the motor output shaft to the correct dimensions and press fit that gear also. Then I was able to mount the gears and another leg. The leg was then mounted on the body so now there are 2 mounted legs, 4 to go.

    I'll take some photos of the next shaft build and assembly process. I'm on call this week so I can't stray as far from home, should be able to get a lot more done. To many other distractions in the summer with bike riding and diving!

    Bob
  • photomankcphotomankc Posts: 929
    edited 2013-07-21 - 20:47:31
    Bob, you might consider a tight slip fit and loc-tite rather than a true press fit. Gives you a bit more leeway between perfect and scrap. Gear to shaft may have too much leverage for that if it's a big gear but a small one is not going anywhere once that cures. I use green loc-tite on bearings now almost exclusively. I don't spend forever trying to shave just the right 1/10 off the bores anymore. +.0005 to 002 is good enough and that bearing is going nowhere unless you put a torch the thing to break the bond. I always have mixed luck with those critical fits on these small machines sometimes they just don't want to cut as you try to sneak in on it and then they suddenly bite and take too much,

    Kudos though if you do it the manly way! :)
  • DiverBobDiverBob Posts: 752
    edited 2013-07-23 - 06:41:10
    photomankc wrote: »
    Bob, you might consider a tight slip fit and loc-tite rather than a true press fit. Gives you a bit more leeway between perfect and scrap. Gear to shaft may have too much leverage for that if it's a big gear but a small one is not going anywhere once that cures. I use green loc-tite on bearings now almost exclusively. I don't spend forever trying to shave just the right 1/10 off the bores anymore. +.0005 to 002 is good enough and that bearing is going nowhere unless you put a torch the thing to break the bond. I always have mixed luck with those critical fits on these small machines sometimes they just don't want to cut as you try to sneak in on it and then they suddenly bite and take too much,
    Kudos though if you do it the manly way! :)
    I never thought about using Loctite for the gears. I'll need to get the shear strength information and calculate the expected torque transmitted through the gear and see if that is a viable solution. I'm moving quite a bit of weight so the shear forces will be quite high. I just cut out the remaining shafts from the stock steel last night and plan on starting on machining one per night. This could save a lot of effort if it works
    Thanks for the suggestion!
  • ercoerco Posts: 19,518
    edited 2013-07-23 - 07:26:01
    Learn from the Corvair guys. If you want to lock a gear to a shaft, use two setscrews on the circle: http://corvairmechanic.com/IMAGE005.JPG
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • DiverBobDiverBob Posts: 752
    edited 2013-07-23 - 09:23:02
    erco wrote: »
    Learn from the Corvair guys. If you want to lock a gear to a shaft, use two setscrews on the circle: http://corvairmechanic.com/IMAGE005.JPG

    That approach might be difficult on a 0.25" dia shaft! But I like it anyway!
  • ercoerco Posts: 19,518
    edited 2013-07-23 - 10:25:12
    OK, then use two hardened 1/16" dowel pins with Loctite on that 1/4" shaft. Still beats making everything all over again!
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • DiverBobDiverBob Posts: 752
    edited 2013-07-24 - 18:38:48
    erco wrote: »
    OK, then use two hardened 1/16" dowel pins with Loctite on that 1/4" shaft. Still beats making everything all over again!
    Since I bent the first shaft, I had to start over again anyway! I did figure out a much easier method of getting the sizing right, got three completed and the last one is half way there. I do appreciate the suggestions and they give ideas for some upcoming parts I need to make that aren't critical for the mechanical operation but would be difficult to manufacture.

    I'll be removing the output shafts from the swing motors to turn them down to size after the last shaft is complete. That machining is a bit tedious as the shafts are long and there is a lot of material to remove. Luckily the shafts are a mild steel that machines nicely.

    I have some photos to post, will get them off the camera and on here shortly.
  • garyggaryg Posts: 420
    edited 2013-07-24 - 20:36:15
    DiverBob
    This is the longest running forum thread I've ever seen.
    Every day, I look for new updates from you.
    You are doing a fantastic job at updating and laying out your experiences.
    Thanks and keep it up.

    GaryG
  • DiverBobDiverBob Posts: 752
    edited 2013-07-25 - 07:20:44
    garyg wrote: »
    DiverBob
    This is the longest running forum thread I've ever seen.
    Every day, I look for new updates from you.
    You are doing a fantastic job at updating and laying out your experiences.
    Thanks and keep it up.

    GaryG

    I'm glad you like the story. This was a way for me to help keep my own motivation up as I knew going into it that it would be a multi-year project and boredom/burnout is always factor. The project has taken several turns that I didn't anticipate but is turning out better than I expected. It's also been pricier than originally planned for but the wife is still supportive!

    I also looked at this as a way to show others what can go into a large project. Hopefully people have seen some new concepts for tackling a problem or see that there is a lot the average person can do at home and get a professional looking product. I've learned a lot about new things to me such as gear box design, anodizing, problem solving using a methodical approach versus just jumping into the deep end! I've gotten myself in over my head on previous projects before but until you try, how else can you determine your limits? It's amazing how many times those things that stand in our path to success can be come little more than bumps in the road once you start to tackle them or research a different approach. If anything this project has reinforced my belief that there a multitude of paths to success, its up to myself to determine which one is right for me!

    Hang in there with me and I'll continue to document the journey, the next phases after the mechanicals are sure to bring their own issues and solutions. I'll be spending some more time over in the Propellor forums again as I've never tried to network micro controllers before.
  • DiverBobDiverBob Posts: 752
    edited 2013-07-28 - 19:05:52
    This has been a pretty productive weekend. I completed all the remaining gear shafts and re-sized the swing motor output shafts. With all this done I was able to finally complete the assembly of all 6 legs onto their mounting assemblies and attach them to the hexapod body. The only remaining thing to work on this week is finishing the modifications to the lift linear actuators and then mounting them. There are still a lot of small jobs to machine but this was the last of the major assemblies to complete and assemble into something other than a pile of parts. My workbench is clearer than it has been for a long time, I actually have room to do some work again.

    The first photo is the raw steel stock for the gear shafts. The 2nd is a gear shaft in process of being machined on the lathe. 3rd is the completed shaft and the parts that make up the gear reduction unit. 4th photo shows the legs standing by to be attached to their mounting assemblies. The last photo is one of the legs getting ready to be mounted. There are a few small spacers in the photo that are used to position the thrust bearings and keep the leg mounts steady.

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    Here are some more photos of the completed leg build. Here are a few views of the outside of the robot and the interior. Normally there would be a aluminum plate on the top of the body but that is sitting on the floor now. The body is sitting on a stand that allows the legs to move freely without touching the floor.

    IMG_3892.jpg
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    There is still a lot to do, will be starting the electrical wiring so lots of crimping coming and testing power flow. Now that all the legs are attached I can see where I have space in the body section to mount the main filter capacitors and the battery for powering the computers. Its crowded in there now and will get even more crowded once all the wiring is installed. I will be designing the next layer above the main body where most of the actual electronics will reside. It has to be shielded to protect it from all the high currents the motors will be drawing. Doing that and designing and programming the electronics should keep me pretty busy well into next year!

    I videoed the assembly process but that takes more time than photos to prepare. I'll finish the video up in a few days and post a Youtube link to it on my YouTube channel. I have several videos there showing the building and assembly processes. There are even some diving videos, my other passion besides robotics! I hope you enjoy this, getting close to Aug 17th, I'll be at the Propeller Expo in Ohio so here is your chance to see it in person. I hope to get one leg up and running on a Propeller Quickstart board so it won't be a totally static display!

    Bob Sweeney
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  • DiverBobDiverBob Posts: 752
    edited 2013-08-06 - 03:14:27
    I finished the mods to the lift motors and installed them. The hexapod looks complete and could stand on its own at this point. Here is a short video showing how the legs are attached to the swing assembly and then the finished robot. I shot this sequence before I finished the lift motor installation but you get a feel for the final dimensions.

    [video]

    Electrical wiring is next; I need to find my electrical schematics and start making up the wiring harnesses. There will be a lot of wires to route and crimp connectors to install!
  • ratronicratronic Posts: 1,451
    edited 2013-08-06 - 09:46:32
    Bob I have been looking at this thread off and on since you started it. That last video was impressive, it is now gaining some mass. I like other's appreciate the fact you have taken the extra time to document your build here. Have you estimated the final weight including batteries?
    Fix it, if it ain't broke! .......... D Rat .......... Dave ..........
  • DiverBobDiverBob Posts: 752
    edited 2013-08-06 - 14:37:51
    ratronic wrote: »
    Bob I have been looking at this thread off and on since you started it. That last video was impressive, it is now gaining some mass. I like other's appreciate the fact you have taken the extra time to document your build here. Have you estimated the final weight including batteries?
    I don't have an exact weight yet but with each leg weighing in at 26 lbs apiece, that's 150 lbs there. Battery and body are looking around 30 lbs so it will be at least 180 lbs before I add in the electronics deck and wiring harness. I'd like to keep it under 200 lbs total as each leg is capable of lifting at least 100 lbs and there will never be less than 3 legs down to share the load.

    Bob
  • ratronicratronic Posts: 1,451
    edited 2013-08-06 - 15:03:35
    I will stay out of Next Large Robot's way! That is a lot of weight to move around.
    Fix it, if it ain't broke! .......... D Rat .......... Dave ..........
  • photomankcphotomankc Posts: 929
    edited 2013-08-07 - 11:59:57
    So..... if Next Large Robot decides it doesn't want to walk somewhere today then Diverbob better have a buddy with him because Next Large Robot probably isn't going to hefted around by one guy. I guess one could make a dolly to go with it so you can haul it around without too much back strain.
  • DiverBobDiverBob Posts: 752
    edited 2013-08-07 - 13:25:06
    It's going to be a pain to move it around until I can tell it to get into the back of my SUV on its own. That will have to be one of the first items to set up once it starts walking! In the meantime I'll have to partially disassemble the robot in order to take it places...
  • DiverBobDiverBob Posts: 752
    edited 2013-08-07 - 19:12:35
    Went to the shop to mount the remaining motor controllers and discovered the delrin parts that the controller mounted on were 0.1 inches to high. No big deal, just use the mill and mill off that pesky 0.1". Started up the mill's computer and got an error, corrupt HAL.dll file. I can't even get into the hard drive to replace the file as windows doesn't start up and no way to get to a command prompt. This is an old, old computer; finally found the recovery disks and even they weren't recognized. So I'm leaving it for tonight and will attack tomorrow. I will attempt to create a XP boot disk so I can first try to replace the bad file and if that fails, reformat the drive and re-install my apps. I hate to do this as there are some CNC files on there that I don't have copies of elsewhere. This is putting a serious crimp in my plans for getting the wiring done!

    Bob
  • DiverBobDiverBob Posts: 752
    edited 2013-08-12 - 05:26:17
    I managed to get the machining done on 3 of the motor controller assemblies before the computer stopped playing so I got those wired up and Molex connectors on the motor wiring. Thank goodness I was able to borrow a Molex crimp tool, it makes crimping much easier and reliable, especially when you are doing dozens of connections.
    Tonight will be soldering connectors for potentiometers and switches on all six legs. If I get the computer back up and running I might be able to get the remaining 3 motor controller assemblies done before the weekend. Hope to see a few of you at the show, stop by and say hi!

    Bob
  • DiverBobDiverBob Posts: 752
    edited 2013-08-14 - 03:26:47
    The guys at work determined that the hard drive on the computer was shot so that sent me searching through all my old IDE hard drives to find one large enough to load XP back on it. I located an old 60 Gig drive and reloaded XP and then the CNC apps to run the mill. Last night I was able to finish milling the remaining motor controller parts and reassembled and installed them.
    The robot is put together about as much as I can do in time for the show. I still need to finish wiring up one leg so I can power it up and maybe run some demo programs. I need to start taking everything apart so I can transport it to the expo, not quite at the stage where I can tell it to climb out of the basement and load itself into the car!

    Bob
  • DiverBobDiverBob Posts: 752
    edited 2013-08-16 - 14:07:32
    Made it to the hotel for tomorrow's Propellor Expo. Looking forward to seeing everyone.

    I couldn't locate the power brick for my laptop which i planned on using to load the Quickstart propellor apps from until late last night and since it hadn't been powered on since last years Expo it had a 'lot' of updates to run. I may not have a leg under power for this showing but people can see the mechanical workings for themselves. I can definitely explain some of the design concepts and the direction I'm taking for the remainder of the project.

    See you later!

    Bob
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