Robot is looking really nice.
You know the metal poles that are sort of "standoffs"? What's the proper name for those, and did you make them your self or are they available off the shelf type of thing?
Dave
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Robot is looking really nice.
You know the metal poles that are sort of "standoffs"? What's the proper name for those, and did you make them your self or are they available off the shelf type of thing?
Dave
http://www.instructables.com/id/How-...fs-and-Spacer/
He made them, but you can buy them as well. This may be helpful for you ^
I made them on my small Chinese lathe. They were actually a pain to make, turning them accurately between centres on a not-that-rigid machine was difficult and took way longer than it should. Happily, though, they all nicely slip into the pockets machined (thousands of miles away!) in the bulkheads. It's amazing how rigid they are, even just finger-tight.
Tonight I finished the faces of the last wheel. Tomorrow I'll probably throw them all on a mandrel and turn the OD. I'll be glad to get past making the nylon parts of the wheels, it's a weird combination of super easy to turn and a schlep because every second pass you have to stop the machine and clear the barbie-hair.
Did you turn down the OD of the spacers or just face off each end then drill and tap each end?
Faced, drilled and tapped both ends and then turned the OD. I have 18mm rod which would fit into the pockets in the bulkheads, but my lathe's chuck is crap and the bolt holes would be eccentric to the point of the bolt not lining up once in the bulkheads.
Looks rather good so far, going to be a cool one to see in the arena! How thick are those bulkheads too, 20mm?
They're 15mm. I would have liked to use 20mm for the sheer chunkiness but there was no way I'd get it in weight. As it stands it's going to be hard to get it under!
There will be 20mm HDPE down the sides, though, so hopefully that keeps out most of the nasties.
More pretendo-botting. The pulleys are just running on bolts so I could see what the belt tension is like, and to take a picture. Pulley distances feel about right. If anything they might be the slightest bit taught, so in running they should loosen just a bit and run nicely.
http://i1088.photobucket.com/albums/...g?t=1393422872
Looking really nice man
Must be heavier than I thought, then! I think 15mm will be by far enough though for bulkheads, especially just for a smaller drum. Definitely going to be one to watch!
Wow this is impressively technical!
Wow, that looks awesome!
Thanks guys^
Had a bit of a pause there as I take care of some unrelated stuff, but tonight saw the completion of the nylon wheel-cores. The rubber is regular bike tyre, picked because the tread has a nice pattern :P. The bushes are "oilon". This is a bit of an experiment. I would have used bronze, but the wheel shafts are 7075 aluminium, and I'm not sure the alu would appreciate it. I have regular nylon on standby should the green stuff flop. It's just nylon with oil (surprise!) mixed in at some point during development, the idea being it's truly self lubricating.
The pulley(s) aren't attached, just sitting in the pockets in the wheels to do this latest incarnation of pretendo. They will be bolted to the nylon.
http://i1088.photobucket.com/albums/...g?t=1394054206
http://i1088.photobucket.com/albums/...g?t=1394054207
http://i1088.photobucket.com/albums/...0292shrunk.jpg
edit: couldn't resist trying to get the tyres to stay folded in place long enough for a pic!
http://i1088.photobucket.com/albums/...g?t=1394057091
I'm loving this build, your skills have improved exponentially
That thing looks angry! Its like a cross between a 4x4 RC car, a bull and an anvil!
Wow, that thing looks evil (in a good way!)
Very nice, shame you can't mount the batteries internally and just stick a bit of armour over the top, it'll look like someone's thrown a mutant rock crawler into the arena! Looking forward to seeing this run with the mini drum too, an impact at speed with that spinning to is going to wreck havoc, I'm sure...
very impressive!! Can't wait to see it drive.
Another slow patch there... need to get in gear!
The drum machining is now organised and will start next week. Discs have been cut and are with Jeroen (machinist). Taper roller bearings for the drum also ordered. These will be held evenly between the bulkheads with spacers and the slightest of preload put on them, like 720.
I recently made the wheel drive shafts. These are 14mm diameter 7075 aluminium with an m6 thread in each end. Can see them in this pile of stuffage:
http://i1088.photobucket.com/albums/...g?t=1394828081
(I have cats!)
Have also made the 20mm HDPE sides:
http://i1088.photobucket.com/albums/...g?t=1394828087
http://i1088.photobucket.com/albums/...g?t=1394828106
The armour supports as well as the wheel shafts are counterbored 5mm into the HDPE. With the front and back on, I'm hoping this will be rigid enough. As-is, in hand, it feels very stiff, but of course spinners can exert a bit more force than human hands. :P
A few with both sides bolted on for a sense of scale:
http://i1088.photobucket.com/albums/...g?t=1394828114
http://i1088.photobucket.com/albums/...g?t=1394828141
http://i1088.photobucket.com/albums/...0413shrunk.jpg
Will probably make the back plate next, which is the weakest side of the machine, being just 12mm HDPE. That is still thicker than Tormenta 2's thickest, but as you can see in the pic with T2 for scale, the 10mm on the nearest side got a 4cm long slot put in it in one blow last year, eek!
That looks epic, one of the machines I'm most looking forward to seeing and fighting
Wow, thats awesome
How did you cut the HDPE so neatly?
A display model tablesaw and hand tool love. :P
Nice! Did mine with a circular saw but don't look anywhere near as good.
The finish on the cut surfaces isn't great. I had to use a non-factory edge for one of the sides and so I just tidied that up with coarse grit sandpaper as best as possible. It doesn't match the other side but, being white, happily all you really see is general white, they only feel different. As long as no one rubs my robot it should be aight. :P
Even a small table saw with the right blade will cut plastic very neatly. I found that a thin kerf blade with a low tooth count meant for ripping wood will cut thru PE, polycarbonate and most other plastics like they were air. The only problem is that the blade will vibrate and leave a somewhat rough edge. If you use a carbide tooth blade with a thicker kerf and still a low tooth count, you can get almost a mirror polished edge, but you need a bit higher powered saw. The secret seems to be avoiding any friction from the sides of the teeth, so using a fence to keep the cuts straight is a key feature.
The overall dimensions are accurate enough with just the regular sold-with blade. The finish is a little rough, and it bites quite easily, but in terms of being close enough to CAD for it to work it does the job. If the finish bothers me I tidy it one way or another. Sadly HDPE just goes gummy and nasty when using fine-finish (fine grit sandpaper for eg) methods, the coarser the clean up often the better. I used a fence for the long cuts, which was a piece of wood clamped to the bed, spaced 6cm from the blade in this case.
To drill the holes I clamped the HDPE pieces to the alu bulkheads and transferred the positions, then used woodworking bits to do the counterbores/sinks etc.
Don't have time/need now, but after the champs I may look at getting a different, more suitable blade for the tablesaw. Intend to work more with nylon as I can source it easily, and from past experience that doesn't cut too nicely with the existing disc.
Some progress. I've cut and partly bolted on the 12mm HDPE back armour. It is currently only bolted to the outer armour (with barrelnuts, for the curious) as I'm reluctant to put many attachment holes in the alu bulkheads until I have all of the width-dictating elements in hand.
Have also done a bit with the base. It isn't structural, all it has to do is keep the electronics in, thus is it just 1mm titanium. I had already cut the wheel cutouts but had to make them much wider to accommodate the (more recently decided) 2" wide wheels. It is also only attached to the outer panels for now. This is done with some inserts I made, which are M10 on the outside with an m6 thread down the middle. Point being I can bash the bolts in and out without wearing out the HDPE and, of course, it's much stronger than that, whilst still less faff than more barrenuts. The coarse thread of the M10 holds well in the plastic - I got the stiffer variety of HDPE with this in mind.
The wheel bodies are only in the pics for mockup purposes, they need a fair bit more work pulley-wise yet.
Said pics:
http://i1088.photobucket.com/albums/...g?t=1395427720
http://i1088.photobucket.com/albums/...g?t=1395427744
One of the inserts. They are 12mm long. No idea how they will work in the long run but they have already made life easier dis/assembling.
http://i1088.photobucket.com/albums/...g?t=1395427751
http://i1088.photobucket.com/albums/...g?t=1395427766
In profile, showing the barrelnuts (I found some black ones, was so chuffed about that! :P)
http://i1088.photobucket.com/albums/...0424shrunk.jpg
Right way up, showing the back.
Jeroen is busying away with the machining for the drum, and Mario is in talks with a company local to him to get 3.2mm hardox watercut for the wedge. Cutting it tight!
Cheers.
Solid AF man. Shame you won't finish in time :P
Wow..........
That looks solid
Lol, hope it gets done in time
Will there be anything holding together/spaced apart the 2 aluminium bulkheads? Or is it just the back plate and the base?
Looks very solid and precision made though.
The inner bulkheads are spaced/held together by the 10mm alu motor mount plate (which is slotted into them, you can see the slots), and the 20mm weapon shaft is also structural; it sits 5mm into the bulkheads and has an m10 bolt in either end clamping the whole lot. The hardox wedge is welded solid and will also play a structural roll, hopefully completely locking up the front.
I wish I hadn't needed to use HDPE for this machine, I fear it'll be the root of many problems, but I had to start building with the design I had, and that design still used HDPE. :P
The back is by far the weakest area. It'll be a matter of luck and driving dictating the fate of the bot.
Randy is looking good Ellis :p
Judging by the slimline profile it might even fit underneath Massacre's blade!
It doesn't :3
It might after a fight or two though. :PQuote:
Originally Posted by harry hills
Jeroen came online and greeted me with some pictures of the machining progress on bits for Rango. I can't really describe how chuffed I am. Give this guy a medal.
First-
http://i1088.photobucket.com/albums/...g?t=1395435475
-these are the drive shafts that transfer power from the right angle gears to the drive. The gears have keyways, as do the pulleys, and I bought some 3*3 keystock. I am completely doing away with setscrews for Rango in the hope it'll make the drive a tad less unreliable. The shafts are 10mm titanium to try and save some grams.
Second-
http://i1088.photobucket.com/albums/...g?t=1395435513
-one side of the drum is done, as is the OD. The threaded holes are what clamp the discs to the drum (5x m8 bolts) and the two holes right on the edge of the drum are for pins, intended to take the big stresses. The bolts would probably do the job alone, but this design means the bulk of the energy is stored in the drum, not the discs, so energy has to be transferred through to the tooth tips. The pins will be bits of 10/8mm ti, the drum is 7075T6.
Also visible here is the weapon shaft. The original was going to be 20mm silversteel (I may still use this if I have the weight) but this one, in more 7075, saves some very welcome weight. I had Jeroen make it, as no amount of adjustment will stop my minilathe from cutting a slight taper, which across 4" is a bit more apparent than I'd like.
Lastly,
http://i1088.photobucket.com/albums/...g?t=1395435486
The half assembled setup. The discs are Creusabro 8000 (cut alongside Harry's weapon bar(s)). For a sense of scale, the drum is 86mm in diameter, the tooth tip covers a 120mm circle.
Once again, Jeroen is the guy behind the machines. I can't wait to get these parts, and I can't wait for the day I might be able to make them myself. For now, that medal really needs to happen. :)
I would be very wary about using titanium for pins - I tried saving weight with some very expensive Ti bolts and every one of them sheared, where the steel bolts never did. Those steel disks look fantastic, keen to see how they rip into the opposition!
The drum looks awesome! Out of interst is this going to be invertible? I assume so but can't imagine how without it running with the drum on the ground!
Also are you using timing pulleys with the timing belts for the wheels or just plain pulleys?
Hey Nick, that's a bit worrying! I'd want a refund, haha. Will bear it in mind.
Max, it isn't very invertable, if that makes sense. The back wheels run on the ground when inverted (and the drum just slides) but there is so little weight over them I doubt it'll do anything. If I have any weight left I'll stick some magnets in the top panel back there in the hope it might give enough grip to prevent being counted out.
All of the belts/pulleys on the drive are toothed.
Looking good that drum reminds me so much of k2
With all those M8 bolts around the drum, I can't see you having any problems with the disks shifting much. BTW: if you are having weight issues, why not bore out the drum a bit more? The weight near the centre of rotation will be adding very little to the KE of the weapon. That might give you back enough weight to add the hold-down magnets.