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Originally posted by pilleya:


In regards to the thickness is there anything stopping builders from layering many circular saw blades together to increase thickness, mass and thus stored KE?

If Nick was aiming to use the blade as a KE weapon or for maximium destructiveness, I think there would be more damaging blade designs that he would utilise. Such as fibre cement cutting blades which have 4 or 5 giant teeth that would be very difficult to break.

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quote:

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Originally posted by Nick:
.I forgot about those cement sheet blades (sadly also TCT) they would do some real damage until the tips broke off.

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When we had an earlier discussion about saw blades, Steve's main concern was people fitting giant sawmill blades or having blades with so few teeth they are essentially a bar. If I make a custom saw blade that has the same dimensions and weight as a commercial design - what's the real difference? If everyone objects, I will just fit a TCT blade of the same weight and it will have the exact same effect on the other bots, just at more expense.
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Quick saw update: I weighed a 254 (10") standard sized TCT saw blade and it was 913 grams, a fair bit heavier than the design with the cut-outs I posted earlier. That means the custom blade is giving up KE and diameter compared to a 'No Questions Asked' commercial blade.
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Mister T:

The welding on the flipper arm is almost done, it just needs a random steel off-cut welded on for a spatula:



About two thirds of the welds are good and the rest are best forgotten - as least I am getting faster with the TIG.
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Getting there - looks like too much heat cause those welds are rather fat and dull coloured. Did you weld it all at once or stitch it all together?
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www.demon50s.com - Minimoto parts
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Definitely too much heat - the trouble is that with lower current I am not getting much of a weld puddle and the filler often sticks to the puddle. Once the steel has heated up a bit, I ease off on the current and I have to be careful the arc doesn't go out completely - there doesn't seem much range between too much current and not enough. I need to move the weld along faster too sometime that works out and sometimes I hit the tungsten with the filler - much more practice needed!
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Less heat input doesn't necessarily equate to lower current use, holding a long arc length and an acute torch angle have a large impact on heat too. going lower on the current can mean a higher heat input because you have to wait longer for the pool to form. Going as high a current as you can keep up with is typically the best way.

Doing everything in 100mm sections as well as alternating sides will keep the heat under control as well, if you did the entire length of that part in one go then that would be tricky for the best of welders.

Dunno about your model but the chinese welders have a pot on the foot pedal that controls the current range. Having it to max makes the resolution really poor. That could be part of it

Doing another tormach order soon if you need anything more as well.
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www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

Thanks for the tips - will try all that today. I am doing really short sections, maybe 30 or 40 mm and then going back the the other end of the part for the next weld. I keep the arc as short as possible and as close to 90 deg. as possible - anything else turns into as disaster! That tip about the foot pedal is interesting; I have been going to 100% at the start of each weld and backing off if I see undercutting or the filler starts balling up. What would be really nice is to see the display while I am welding - perhaps I can set up the video camera to watch the welder while I call out how the weld is looking.

RoboGames 2017

I just read that Robogames 2017 is being held on a date that I can probably make . With almost a year's notice and maybe a month of work needed on the lightweight bot, I can have it packed well in advance and bounce from UK Robo Challenge to US RoboGanes. Next April is RoboMonth
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Coincidence - or fate?

Not even an hour after finding the new date for RoboGames, these new aluminium ring gears arrived for the Lightweight:



They will save a useful amount of weight off the drive train once I machine them to size. For now, its back to welding practise.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

one suggestion if you aren't already, angle that arm so that the weld puddle wants to naturally sit into the corner. Much easier than trying to handle a vertical edge.
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Mechanical engineers build weapons, civil engineers build targets

Here is how I typically hold the torch for that type of weld:



The torch is angled forwards just a bit to make it easier to get the filler into the puddle without hitting the tungsten. Angling the part makes for a difficult body position - standing up, leaning over the part AND keeping a foot on the pedal is a circus act, not welding; at least for my skill level .
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Half the art for good TIG is preping your environment, TIG whilst standing is *much* harder than sitting.
For that part I'd aim to be sitting right arm resting on the bench holding the torch, wrist resting on the job if it was practical. With the part propped up so that join was sitting at a 45 degree angle so the pool wants to just sit in there.
Left elbow resting on the bench to steady the filler rod.

I'm yet to master the art of one handed feeding of the filler rod though :-< watching the pro's do it its like how do you keep it still and move it all at the same time.

I've yet to use a pedal but our welder has 4 button mode which lets you have 2 power levels you can change between by touching the torch button during the weld. I normally set low power to about 70% of regular power. It's not such an issue in steel but for Al it makes a difference as the whole job heats up as you go along.
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Mechanical engineers build weapons, civil engineers build targets

Thanks for the tips Jake, I will think about how to prop the parts up without raising them up too high to sit in front of.

New welding problem :

I tried creating more space in front of the torch to help dip the filler faster without touching the tungsten, I turned down the current and increased the stick-out by 5mm so the total was about 1.5 times the gas lens diameter. The torch was more angled forwards, around 30 to 45 degrees:



What a shameful mess! Due to all the soot, I'm going with not enough gas coverage, even though the regulator is set to a 20 CFM hurricane. I went back to my usual stick-out and torch angle and the next weld came out like this:



Lightweight:

The aluminium ring gears have replaced the original steel ones; they saved a very pleasing 312 grams, far more than expected.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

quote:

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Originally posted by pilleya:

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If you are hitting the tungsten with the filler I wonder if you are too close?
My arc length is normally like 5mm or so I think.

I can dip the rod into the pool directly and then as I move the torch along it'll melt it off the rod. It's not how you are meant to do it I think lol. I think you are meant to move the torch back and then dip the rod into the still molten pool.

I have the rod basically sitting in the groove to be welded. Only thing to watch for is if the rod is touching the work in 2 places it'll often weld itself in place from the current flowing through the part.
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Mechanical engineers build weapons, civil engineers build targets