Update
The continued lack of employment has stopped any decent robot progress recently but in a few weeks I'll be moving up to Aberdeen to start a new job. Downside is that I'll be in a 1-bed flat with no workshop to hand, so been spending a fair bit of time in the Cave of Blunders while I can. After servicing the robots from the Deeside event, I needed something else to do, and got thinking:
Always fancied the idea for Carcinus but ended up building the axe for it instead, then developing Onyx when the axe put Carcinus overweight. But a quick search around my various spares and I realised I pretty much had all the parts to do a Dead Metal style saw, similar to the Series 1 design.
Firstly I needed a method of swinging the arm. I had enough chain spare from Onyx and some sprockets to make a 3:1 chain transmission from a drill, but knew that would still be too fast, so decided to have a bash at making a three-stage drill gearbox.
Welded two ring gears together (absolutely shoddy welding I know, but sufficient), trimmed them down and stuck the gears in:
Then because the plastic gearbox plate that mates to the motor wouldn't fit on, I needed a way to join it all together. Cue some parts from an old GR-01, using the motor plate at the rear and the front plate (minus the bearing) to bolt everything together. Bit of a hybrid unit. Stuck the 10-tooth sprocket on the drill output and that was done:
Then made some bulkheads to secure the motor and mount the bearings for the arm shaft. It would be neater and lighter if I got some needle rollers and pressed them into the bulkheads but these were in the spares pile I was working from and have been sitting doing nothing since 2007:
The saw arm is a bit of box-section that I pulled out of Scar's insides, cleaned up with a couple of nuts welded on. M6 bolts go through these nuts and tighten against a couple of flats on the shaft (M12 bolt) and grub screws secure the large sprocket and bearings to the shaft, resulting in the whole thing rotating when the motor spins:
I had hoped to use an old angle grinder gearbox to connect the saw blade to the motor but it proved unsuitable so I'm going to have to make something custom and more reliable once I've started earning again and have the time. Currently it just has a cutting disc bolted on through some Nylon to complete the look; I hooked up the HTI motor I was planning on using via timing belts and pulleys and it sounds menacing but there are no bearings between the sawblade shaft and the nylon that's holding it on so things got hot and melty pretty quickly.
Still need to weigh it to see where it's currently sitting but pretty happy with it so far. Got an Electronize controlling the arm and got a spare SSR for the blade motor, though the Electronize will get upgraded to a TZ85 at a later date to give more precise control.
And finally, if you were able to sit through that, the customary video:
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