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Jolt & friends - Team Overkill - NSW
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Cpnwolfe



Joined: 29 May 2012
Posts: 449
Location: Rockhampton/qld


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those are some huuuge ass bearings nick
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Post Tue Feb 06, 2018 10:24 am 
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Nick
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Joined: 16 Jun 2004
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Location: Sydney, NSW


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The front ball bearing in Scissorhands broke several times so I went with a monster roller "just in case". According to the spec sheets, the roller bearing has over four times the dynamic load bearing capacity.

You just reminded me to go to H&F for a proper threading cutter - let's see how long it takes me to learn threading on the lathe Wink.
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Australian 2015 Featherweight champion
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Post Tue Feb 06, 2018 10:58 am 
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Nick
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Location: Sydney, NSW


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Thread cutting:

I bought a thread cutting kit yesterday; this one has tools for external & internal threads for just a few $$$ more than a single tool. That was super important, as you'll see later.



I already have a bag of imperial 1" - 14 TPI locking collars so it made sense to cut the weapon shaft to use them (or so I thought!) The lathe is metric but says it cuts imperial threads too. What isn't mentioned is that all the convenience features like the threading dial don't work for the imperial threads Mad.

To cut a 1" thread, you have to leave the half nut engaged from start to finish and reposition the cutter by running the motor in reverse - pretty brain dead and error prone IMHO.

The weapon shaft has a wide shoulder and the thread has to be cut quite close to it. The safest way to cut a thread up to a shoulder is to turn the cutter upside down and run the lather in reverse so that the cutter moves away from the shoulder and cannot crash into anything. Unfortunately turning the normal exterior cutter upside down meant it could not get anywhere near the shoulder and I had to try the internal cutting tool like this:



After many shallow cuts and slowly backing up the carriage, the thread came out really well:



This is how the weapon looks when assembled:


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Post Wed Feb 07, 2018 5:58 pm 
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Eidg



Joined: 27 Nov 2015
Posts: 10
Location: Switzerland


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I am using 2x 30204 x from skf on my feather.
The bearing block looks pretty good, is the collar made out of steel?

Post Thu Feb 08, 2018 5:50 am 
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Nick
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Location: Sydney, NSW


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The locking collar is stainless steel - I usually use a stronger alloy steel collar but this SS one was the first one I found Smile

The bearing block was made quite some time ago and for a slightly different design. I am already thinking about an update that weighs less and fits the latest bot design better.
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Post Thu Feb 08, 2018 10:13 am 
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Valen
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Joined: 07 Jul 2004
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Location: Sydney


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That's a fine looking thread there Wink
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Post Fri Feb 09, 2018 10:44 am 
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MoonSet416



Joined: 25 Sep 2016
Posts: 432
Location: Sydney


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I guess you could flip the spinner blade around to get it a bit closer to the ground. (assuming your test setup is inverted compared to what would go into the final bot.)

Post Sat Feb 10, 2018 10:31 pm 
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Nick
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I didn't even notice which way the blade was on in the photo - you are quite right and that is the way Scissorhands had the bar with the teeth facing down.
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Post Sat Feb 10, 2018 10:34 pm 
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Nick
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Location: Sydney, NSW


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Belt tensioner:

In the test rig, its easiest to move the bearing block to tension the belt but that isn't practical in a bot. It needs a movable tensioning roller or 'back-breaker' pulley like this:





The roller has two small ball bearings on an 8mm screw and is very solid, it should take plenty of abuse and since its tucked behind the weapon shaft, its not likely to take direct hits.

The system is designed to take an 8 to 10 groove belt but I only have this 5 groove belt for testing. Its still very grippy and I can;r make it slip while turning it by hand. The next step step is to add some strengthening the the support plate and then its time for a spin-up.
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Post Sun Feb 11, 2018 11:35 pm 
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Cpnwolfe



Joined: 29 May 2012
Posts: 449
Location: Rockhampton/qld


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looks way to nice, can you put some dings and random holes in it for us plebs please Razz
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Post Mon Feb 12, 2018 9:15 am 
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Nick
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LOL that piece of ali sheet has been used for two other projects already - will drill out some holes to make it more used looking. Maybe some random pop rivets and a splash or paint too.
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Post Mon Feb 12, 2018 9:20 am 
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Nick
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Location: Sydney, NSW


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More fun with carbon fibre:

I can't find any more design issues with Jolt's electronics module, so I ditched the MDF prototype for CF:



Its a little difficult to see but the receiver is on a separate plate on spacers over the ESC, which saves a heap of space. Now its time to add the power & signal wiring; not my fave part of the build.
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Post Tue Feb 13, 2018 8:04 pm 
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Nick
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Location: Sydney, NSW


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The "ultimate" power switch:

The power wiring for the lightweight has been givving me all sorts of problems; too bulky, ugly, too stiff, etc. After several failed attempts, I have come up with the most overkill solution possible Smile.



The switch has a Delrin body to hold the 1/2" copper contact bars, I used an extra bar as a giant solder cup to keep the negative wiring neater.



When the parts are assembled, the switching is done by screwing the bolt in; it will be replaced with an M8 copper grub screw once everything else has been tested.
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Post Tue Feb 20, 2018 7:42 pm 
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Nick
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Location: Sydney, NSW


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The switch progress is good: the copper bars are glued in securely and line up so the screw goes through them. The mounting holes are drilled and tapped and the switch is all mounted:



I also drilled new mounting holes for the electronics so tomorrow I can trim all the wiring and solder the connectors.
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Post Thu Feb 22, 2018 10:26 pm 
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Nick
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Location: Sydney, NSW


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Lightweight:

The switch and wiring harness is almost finished - just the power light connector to solder on. That means there is a really good chance of a power test over the weekend - really looking forward to that!

Sportsman:

The next event is for sportsmen in May, hopefully enough time for me to resurrect Mr T. It still needs a heap of titanium welding and electronics work so maybe other projects will have to on the back burner for a while.

Lathe Day:

The new lathe got its first overhaul today; everything had new grease or oil, the gibs were tightened and most of the swarf was cleaned up. Tightening the gibs made a huge difference, I think they were a little loose from the beginning.

I also made the parts to mount an ER32 collet in the spindle. Its a super handy option for small parts and has higher concentricity than a 3 jaw chuck without messing about with a 4 jaw chuck - its showing under 0.01mm run-out Very Happy.


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Post Fri Feb 23, 2018 7:39 pm 
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