Next large robot

13468923

Comments

  • DiverBobDiverBob Posts: 634
    edited August 2012 Vote Up0Vote Down
    doggiedoc wrote: »
    I'm eager to see the video when that comes to fruition!

    Paul

    So am I!
  • DiverBobDiverBob Posts: 634
    edited August 2012 Vote Up0Vote Down
    Finished up a fun day at UPENE. It was great to see familiar faces and meet some new folks. Lots of interesting projects and discussions with like minded people. I really look forward to next years get together!

    The Hexapod performed fairly well, initially had problems with the tibia motor, it wouldn't respond at all. Finally moved the signal wire from P12 to P13 and all was well again. I don't know if this means the I/O pin is bad or not, some additional testing will be required. Since the calibration for the Coxa isn't quite set properly I didn't run any of the continuous running programs and instead just manually ran each motor using push buttons.

    It's back to work again next week, fixing the impact sensor housing design, looking into making the leg section .5" wider. Lots of work ahead! It may be time to take a break and jump into the anodizing for a change of pace. Something new to learn and experiment with....

    Bob
  • Roger LeeRoger Lee Posts: 339
    edited August 2012 Vote Up0Vote Down
    That took a lot of effort just to haul it to UPENE 2012. Big and massive bot.
    You could have taken the easy way and brought photos/videos, but you took the hard way.

    I want to say THANK YOU.

    absolutely great, impressive machine.

  • DiverBobDiverBob Posts: 634
    edited August 2012 Vote Up0Vote Down
    Roger Lee wrote: »
    That took a lot of effort just to haul it to UPENE 2012. Big and massive bot.
    You could have taken the easy way and brought photos/videos, but you took the hard way.

    I want to say THANK YOU.

    absolutely great, impressive machine.

    Thanks for the compliments Roger, it was good to see you and your wife again. This week will be minimal robot stuff, getting ready for a week of diving shipwrecks in northern Lake Huron. Should be refreshed and ready to dive back into it once I get back!
  • DiverBobDiverBob Posts: 634
    edited September 2012 Vote Up0Vote Down
    Got 15 new Parallax HB25 motor controllers in the mail! Now I'm ready to run the leg motors! Just have to get the legs built....

    Bob
  • ercoerco Posts: 18,942
    edited September 2012 Vote Up0Vote Down
    DiverBob wrote: »
    Got 15 new Parallax HB25 motor controllers in the mail!

    That will keep Parallax in the black for a while... :)

    I'm starting to feel inadequate; I don't own a single HB-25. Maybe I should start hoarding. They're only $40 in 20+ quantities: http://www.parallaxdirect.com/cart/catalog/Parallax-29144-HB-25-Motor-Controller-197.html
    "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: 634
    edited September 2012 Vote Up0Vote Down
    It's been a while since my last post, been taking a break from robotics and working on everything that got neglected over the summer. I was starting to get burned out so I was ready to jump in again.

    Started the leg impact sensor modifications, it looks like my idea of using another oring to help keep the leg centered will work, need to do some more experimenting to figure out dimensions of the support. I was also disappointed that some of the mounting holes weren't lining up, miscalculated one of the part dimensions. I'll have to redo that piece again.

    Ordered some more aluminum for some mods to the width of the legs. I'll test out those changes once I get the stock.

    I had a lot of reading to do to catch up on all the new entries in the forum, still working on that!

    Bob
  • doggiedocdoggiedoc Posts: 1,996
    edited September 2012 Vote Up0Vote Down
    Everybody needs a break from stuff now and again. It's all about balance. :D Glad you're back in the groove.
    Some times my mind seems to wander..... these days I just tag along.
  • DiverBobDiverBob Posts: 634
    edited October 2012 Vote Up0Vote Down
    I'm getting geared up to start cutting out the remaining legs for the robot. I did a count of the bearings and found I was 24 short since I decided to use only one size. Luckily my wife is in Florida visiting her Dad so she is stopping at Orlando Skycraft Surplus to pick up more of the right sized bearings. I have to adjust the CAD drawings again to match, that should finish up today.
    I'm using bearings with an 0.625 OD so I'm ordering a undersized reamer of 0.6245 to make press fit holes. That is another step I'll have to add to the g-code programming on all the pieces. Since I haven't gotten my full flood coolant system and enclosure set up yet, I'm going to use WD40 on a paint brush and compressed air to lube and blow the chips out.
    This going to take some time to make all 6 leg parts, have patience, my goal is to have them together by the end of the year. I don't know if I'll get the anodizing in yet, still have to get supplies for for that and spend some time experimenting.

    Bob
  • jdoleckijdolecki Posts: 692
    edited October 2012 Vote Up0Vote Down
    Found this Picture online thought you might like it.

    robot.JPG
    609 x 707 - 92K
  • DiverBobDiverBob Posts: 634
    edited October 2012 Vote Up0Vote Down
    Great photo, I thought I'd seen all the published pictures but this is a new one for me!

    Got the reamer and a R8 collet to hold it from McMaster Carr. I need to finish up converting the rest of the CAD files to CAM so I can Blackplot and then test the code. Maybe I'll be able to start some cutting this weekend! The mill has been quiet for too long...

    Bob
  • ercoerco Posts: 18,942
    edited October 2012 Vote Up0Vote Down
    Neat old photo. Odetics was making the Odex 1 robot in Roanoke (Jae Valley Rd, IIRC), not far from my alma mater Virginia Tech. Unfortunately, I had just moved to LA when I learned of it ~1984, otherwise I would have been their most frequent visitor. I was hoping to find a video of it walking in & out of the pickup bed, but no go.
    950 x 581 - 47K
    "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: 634
    edited October 2012 Vote Up0Vote Down
    Good video, hadn't seen that one either. First time I've seen it climbing stairs also.
  • DiverBobDiverBob Posts: 634
    edited October 2012 Vote Up0Vote Down
    This hasn't been a couple of good days! Got all the CAD drawings updated and have spent a significant amount of time running the CAM portion of the software only to find that 2 of the more intricate parts caused a hard crash the BobCad software when I try to post the gcode. I finally ended up having to go back to square 1 and redo the original drawing. Never did figure out that was causing the crash, no error messages, just stopped the program and it would then shutdown.

    Going back through all the CAM files, I bought a copy of GWizard software which allows me to enter the sizes of the milling end mills and drills to give more accurate speeds and feeds. I'm using that info to make updates to even the previously completed CAM files. With the number of parts to be generated it makes sense to try and add a little bit of efficiency into the process!

    Bob
  • photomankcphotomankc Posts: 929
    edited October 2012 Vote Up0Vote Down
    GWIZARD is a fantastic bit of software. I know I have had a much easier time not burning up tools since using it. One thing, take the "rougher" feeds and speeds with a grain of salt. My only significant sized (3/8") snapped tool was from just running what GW said would work there. Smoke, rumbling, squealing, stalling, and snapping resulted. AL was melted to the remaining tool like it was built from it. Some choice words were uttered that afternoon.

    Otherwise I stay conservative in the settings and my tools last forever and I can often cut faster than I thought I could. I find it very, very, useful.
  • idbruceidbruce Posts: 5,570
    edited October 2012 Vote Up0Vote Down
    Hey Bob

    This is the first time I took a peek at this thread, and I must say that your project is very impressive, with the addition that your videos are outstanding and very informative. Not that my opinion matters much, but I would have to say that you are an extremely intelligent and highly talented individual.

    I thought I was fairly intelligent until I found this thread, but now I feel stupid :)

    Bruce


    Novel Solutions - http://www.novelsolutionsonline.com/ - Machinery Design • - • Product Development
    "Necessity is the mother of invention." - Author unknown.

  • DiverBobDiverBob Posts: 634
    edited October 2012 Vote Up0Vote Down
    idbruce wrote: »
    Hey Bob

    This is the first time I took a peek at this thread, and I must say that your project is very impressive, with the addition that your videos are outstanding and very informative. Not that my opinion matters much, but I would have to say that you are an extremely intelligent and highly talented individual.

    I thought I was fairly intelligent until I found this thread, but now I feel stupid :)

    Bruce
    Thanks for the kind words but I'm not done yet! I've still got my fingers crossed that all this works out the way I'm planning! It is taking longer than expected but this project was expected to take a couple years and I'm only 11 months into it. Finishing out the rest is highly dependent on the checkbook status and keeping up the motivation. This thread is part of my motivation, I feel guilty if I haven't done anything to write about with so many people following this saga.

    I did get about half the CAD/CAM files updated last night, should finish them out tonight. The next step will be to use Backplotter software as the initial validation on g-code and tweak the code for efficiency. Then I'll be ready to start trial cuts.

    Bob
  • DiverBobDiverBob Posts: 634
    edited October 2012 Vote Up0Vote Down
    All the CAD drawings are done and the CAM files have been generated and tested using backplotter software. I had to create a fixture to hold the left and right side swing arms and the upper and lower leg pivots. Because all sides of each of these parts require machining I can't just hold them in a vise directly. The fixture allows me to drill some holes through the part first and then bolt it to the fixture plate which is held in the vise instead. The bolts are removed at specific points in the machining process but this way the part doesn't move.
    I've been working on the right swing arm and am taking a break right now. The first go round on the part failed because I didn't align the aluminum blank correctly for drilling the holes so the holes were drilled about 0.050 inches off. Of course this threw everything else off also. On the next aluminum blank I got the command to stop the end mill in the wrong location since I needed to stop and remove the bolts holding the part and change the clamps. This means I busted a $35 end mill on the bolt head. At least I was able to remove the destroyed bolt. Before I mess up anything more, I rechecked where the proper location for the mill stop should be and inserted the appropriate code. Now I need to go back and try again.

    I have pictures and video to show of the slow progress over the last 2-3 weeks that I'll get out tomorrow when I stop.

    Bob
  • DiverBobDiverBob Posts: 634
    edited October 2012 Vote Up0Vote Down
    I redesigned the swing arms for the robot to be a little bit beefier since I was putting in larger bearings. The first time I machined the parts I spent a lot of time moving clamps around because the part is machined around the outside and inside. To speed up the process I made a fixture plate out of some scrap Aluminum with holes drilled and tapped to line up the part. This way I can clamp the part blank to the fixture, drill the holes and then use those holes for bolts that hold the piece down. This worked out pretty good today with only a couple of issues to work around. I got both a right and left side swing arm completed. The same fixture will be used to machine the upper and lower leg pivot blocks. I may even set it up to do the pantograph parts also, the fixture is large enough to do a couple of parts at the same time.

    Here is a short video of the machining operation, for some reason it won't let me imbed the video so here is the link instead. The only thing not shown is reaming the bearing hole at the end. I used a 0.6245 ream but that turned out to be too large. I then found out the digital caliper I've been using for 15 years is off by about 0.001 inches. So I will have to use either Locktite or peen the inside reamed surface to add some additional metal. I ordered another reamer tonight, 0.6235 that will be correct for this. I need to get another digital caliper, have wait on that until payday.

    http://www.youtube.com/watch?v=ErACVU50qhQ

    It was nice spending the weekend on the mill, especially when things go wrong you learn something new!

    Bob
  • vanmunchvanmunch Posts: 567
    edited October 2012 Vote Up0Vote Down
    Very cool, thanks for the update.

    Dave
    My wife is very, very understanding

    Prospero: Robot Farmer
    http://www.youtube.com/watch?v=ACtihXjq2B0
    www.DorhoutRD.com
  • DiverBobDiverBob Posts: 634
    edited November 2012 Vote Up0Vote Down
    Not much to show for this week. I did upgrade my BobCad from version 23 to 25. Got the program and training videos late Friday so spent the weekend installing and configuring the software. There are 10 video disks with a huge number of videos covering just about every menu item and how to put it all together. I went through several of these and re-ran my CAD files in the new system. It has a simulation capability that is really nice for checking out and verifying everything cuts the way you expect.
    I'll finish up using the new simulation on each of the parts before I cut them so ill get started on that in a couple of days. The program has a recording of the simulation that ill post for some of the parts once I check it out.

    Bob
  • DiverBobDiverBob Posts: 634
    edited November 2012 Vote Up0Vote Down
    Finished updating all the old CAD files but the posting code for g code wasn't working right so no cutting this weekend... Luckily I just got off the phone with Tech Support and most of the issues were fixed, they are finishing up the rest and emailing the fix tomorrow. Since I'm on call this ill have lots of time after work to play some more!

    Bob
  • DiverBobDiverBob Posts: 634
    edited November 2012 Vote Up0Vote Down
    It's been a frustrating day in the shop.. I got the software updates installed and that fixed the issues I was having. So started to cut "air" to test the code and I kept having one problem after another with it not cutting right. Stopped everything and went a modified the CAM post processor, that took care of almost all the problems in the code, still a couple of things I was able to manually fix so I could go on. Finally ready to cut metal and everything went well until the last cutter, a 0.6235 reamer that ended up cutting a 0.672 diameter hole! I just gave up for tonight and will try again tomorrow.

    I miscalculated the amount of aluminum I need for this part and with all the waste parts so I'll need to buy another 6 ft piece soon. I'm ready to start cutting the remaining legs but the software and machine are conspiring against me!

    Bob
  • DiverBobDiverBob Posts: 634
    edited November 2012 Vote Up0Vote Down
    Still don't have an answer for why the reamer isn't cutting correctly other than there is too much vibration. However reamers are supposed to 'float' so they self center. I ended up manually turning the reamer in the spindle in order to get a clean hole.
    Once I finally got the left swing arm cut I decided to do the right side swing arm. On this one all went well until the bearing holes were cut, wrongly. The holes are about 0.15 inches off. I checked and the 0,0 point of the machine was off, how that happened I have no clue at this point. Anyway I'm down to my last chunk of that size of aluminum so I'll try one more time tonight. Either way I will be ordering an additional 96 inches of 3 x .25 aluminum.

    My next attempt at making scrap metal will be the pantograph arms. Each one is 7 inches long. There are 2 types, the upper arm has 3 bearing holes and the bottom arm only has 2 .25 bolt holes. These should go faster and they are a much simplier design.

    Bob
  • DiverBobDiverBob Posts: 634
    edited November 2012 Vote Up0Vote Down
    Decided to cut up all the 1" x 0.25" aluminum for all the legs. Once that was done, fired up the mill and started cutting out the lower extension for the leg. Here is a short video of the machining process for this part.

    I made up all 12 lower extension parts last night and started the Upper Extensions tonight. I'll post that video later.

    Experimented and came up with a method to get a good ream on the bearing holes so that hurtle is figured out. I ordered more aluminum for the swing arms but that didn't show up as expected Friday, so I'll continue to work the other leg parts.The goal is to have the upper extensions done by tomorrow evening and start on the upper and lower leg pivots. These parts have a lot of tapped holes to do after machining, that will take a day or two by itself!

    This part of the project has taken me longer than expected, upgrading the CAD/CAM software added more unexpected issues that just took time to resolve. I think most of that is behind me now and I should be able to get the parts made up. Continuing to document the progress on the project, this also helps me stay motivated and keep my breaks to a reasonable time. I would still like to bring a mechanically complete robot to one of the next Parallax Expos however I don't expect to have it under full computer control for a while longer.

    Bob
  • photomankcphotomankc Posts: 929
    edited November 2012 Vote Up0Vote Down
    Bob, if you don't mind saying, what ended up being the fix for the reaming issues you were having? I assumed that the numbers you gave were a mistype (.6235 -> .672) and you meant (.6235 -> .627). I know in most instances 0.0035" oversize on a ream is disaster but It would have had to swinging like a boring bar to cut 0.048" oversize! I have found that despite the claims of flexible self-centering, that the only way to get accurate reams was to mount them in a good collet chuck, not a drill chuck. Every time I have used a drill chuck the results have been poor. There are plenty of times where it didn't matter that much but when it does the only way I can get close is with a collet and even then I always seem to cut close to 0.0005" oversize. Reamers are fiddely things and not my favorite tool, I much prefer to bore the holes when the tolerance is tight.

    I was just curious though what ended up being the issue.
  • DiverBobDiverBob Posts: 634
    edited November 2012 Vote Up0Vote Down
    photomankc wrote: »
    Bob, if you don't mind saying, what ended up being the fix for the reaming issues you were having? I assumed that the numbers you gave were a mistype (.6235 -> .672) and you meant (.6235 -> .627). I know in most instances 0.0035" oversize on a ream is disaster but It would have had to swinging like a boring bar to cut 0.048" oversize! I have found that despite the claims of flexible self-centering, that the only way to get accurate reams was to mount them in a good collet chuck, not a drill chuck. Every time I have used a drill chuck the results have been poor. There are plenty of times where it didn't matter that much but when it does the only way I can get close is with a collet and even then I always seem to cut close to 0.0005" oversize. Reamers are fiddely things and not my favorite tool, I much prefer to bore the holes when the tolerance is tight.

    I was just curious though what ended up being the issue.

    Believe it or not, those were the actual numbers I got on the hole. Lots of chatter and the cut hole was very ragged. I've used reamers before on other mills but this was the first time on a CNC.

    I did a lot of experimentation with different speeds and feeds and in every case the hole ended up too large, sometimes by a significant amount. The reamer itself is HSS and 0.0005 undersized for the bearing. I use a good quality R8 collet and the mill is fairly rigid. I couldn't detect any vibration in the workpiece while using the reamer either. I couldn't find any help on the Internet machining sites that I hadn't already tried and was ready to just program the end mill to cut the hole instead. As a last resort I tried manually feeding the reamer in the Z axis and manually turning the reamer by hand. This method actually worked pretty good although I modified the turning by hand to using a socket and ratchet which sped up the process quite a bit. Since the hole is only 0.215 inches deep it takes less than a minute to do it this way.

    I think if I changed the motor speed v-belt to the lower pulley that I could duplicate the slower speed but it would take more time to swap pulleys for each part than to just do it by hand. The lowest speeds possible using the standard pulley don't have enough torque so the that limits the low end speed. This is a work around but until I do some more experimenting I will stick with what works! I figured that I only have 18 holes per leg to ream!

    Bob
  • Ken GraceyKen Gracey Posts: 6,185
    edited November 2012 Vote Up0Vote Down
    Bob, I know I asked before but have you tried flood coolant on these CNC processes? I think you'll be really impressed with the finish quality, absence of material galling, and increased feed rates.

    You have so much patience to undertake such a long-term project. I wish I had that ability.
  • DiverBobDiverBob Posts: 634
    edited November 2012 Vote Up0Vote Down
    Ken Gracey wrote: »
    Bob, I know I asked before but have you tried flood coolant on these CNC processes? I think you'll be really impressed with the finish quality, absence of material galling, and increased feed rates.

    You have so much patience to undertake such a long-term project. I wish I had that ability.

    Can I quote you on the patience remark? My wife might like to know that!

    I would love to get a either a flood coolant or mister up and running but I need to get an enclosure for the mill done first. I've figured out the parts needed (I want to use 80/20 framing for this) but am waiting for a cash infusion to get that started. In the meantime I'm using WD-40 in a squirt bottle and brush. WD40 is a pretty good lubricant for aluminum, I'm pretty satisfied with the finish. The vibratory bowl does a good job of removing the remaining tool marks and leaves a nice satin finish. I'll be anodizing that finish once I set up an anodizing station, hopefully before spring.

    Bob
  • photomankcphotomankc Posts: 929
    edited November 2012 Vote Up0Vote Down
    DiverBob wrote: »
    Believe it or not, those were the actual numbers I got on the hole. Lots of chatter and the cut hole was very ragged. I've used reamers before on other mills but this was the first time on a CNC.

    I did a lot of experimentation with different speeds and feeds and in every case the hole ended up too large, sometimes by a significant amount. The reamer itself is HSS and 0.0005 undersized for the bearing. I use a good quality R8 collet and the mill is fairly rigid. I couldn't detect any vibration in the workpiece while using the reamer either. I couldn't find any help on the Internet machining sites that I hadn't already tried and was ready to just program the end mill to cut the hole instead. As a last resort I tried manually feeding the reamer in the Z axis and manually turning the reamer by hand. This method actually worked pretty good although I modified the turning by hand to using a socket and ratchet which sped up the process quite a bit. Since the hole is only 0.215 inches deep it takes less than a minute to do it this way.

    I think if I changed the motor speed v-belt to the lower pulley that I could duplicate the slower speed but it would take more time to swap pulleys for each part than to just do it by hand. The lowest speeds possible using the standard pulley don't have enough torque so the that limits the low end speed. This is a work around but until I do some more experimenting I will stick with what works! I figured that I only have 18 holes per leg to ream!

    Bob

    Wow! That is really astonishing. I can't picture how it could get to 50 thousandths oversize but I have to believe you if you measured it. The rule of thumb I have always heard was "Half the speed, twice the feed" of the same drill and I have had decent luck under CNC control holding to within 0.001" on a reaming pass just holding to that. Maybe if you can pop out a video of what's happening sometime you could get some feedback. My converted machine still has it's quill for these kinds of ops too. I have used that to get a better feel for how much resistance/vibration there is and sometimes it's nice to use that for easier tapping. Anyway, sounds like the hand turning method is working for you even if it's a tad slower. You're right though, changing belts all the time can quickly chew up any CNC time savings.

    You gotta palletize that stuff! Bet you could get 6 to 8 of those parts on the table with a fixture ;)
Sign In or Register to comment.