Team Coolspeedbot: first feather weight robot

[Coolspeedbot]

Hummm, might look into it but I can only go 1 or 2mm thiner at best.

[maddox10]

The thinnest Hardox 450 I have worked with is 1/8" or 3.2mm.

I heard about thinner stuff, but never had the pleasure to see it.

[shakesc]

you wont get 1mm or 2mm hardox
SSAB did a run of 2mm but that was it, really just beetleweight stuff

[Coolspeedbot]

After another bit of Maths and some tweaks with the CAD I think I got a bot that should be possible to make. with the bot using 4mm hardox instead of 5mm it can free up weight. Now I have emailed K-cut about cut tolerances and got a response, but I wanted to check with people here.

Should holes be made lightly bigger then I need them to be and add a millimetre or two around the parts to insure they are not cut too small?

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[R9000]

Yes. It's a huuuuuge pain when you have to enlarge the holes yourself.

[Coolspeedbot]

Yes. It's a huuuuuge pain when you have to enlarge the holes yourself.

thats why I wanted to be sure.

[Andy]

To be extra safe I normally make most holes 0.5 bigger than needed on 4mm parts, but for some holes where strength is important I have gone to 0.3 oversize through 10mm thick hardox (higher taper) and they have mostly been ok after a small amount of work with a needle file, for your design id say go 0.4mm or 0.5mm the intended size and it should be fine.

[overkill]

Like Andy says, clearance around holes is a must. A 0.5mm oversize hole is pretty standard (that's just 0.25mm clearance) for drilled holes and for laser or waterjet cut holes, as much as 0.75. Small waterjetted holes are often not particularly round and I like to clean them up using a Dremel with a tungsten cutter.

[Coolspeedbot]

I see, well looks like I made everything 0.5mm too big from you guys have said.

[overkill]

Its not a big deal unless you are using soft material or really crappy screws

[Coolspeedbot]

So it looks like I'm 'done' with CAD in regards to the hardox stuff. I just need to save up a few hundred pounds for it (he says not knowing the approx. cost).

[Coolspeedbot]

So I said I was done with the electronics, but I still need to fit a power light. I've fitted a plug ready to connect the light but I would like to double check what light I should get. whats the minimum voltage I should get? if I need resisters what should I get it?

[overkill]

I guess you are going to use an LED? They all work on about 3V and will definitely need a dropping resistor. Some LEDs come in a mount with a resistor and you might be able to find one that matches your battery voltage - you really can't over-volt LEDs and expect them to last, so don't be tempted by something that's close.

Finding the resistor value is dead easy; just google 'LED resistor calculator' and pick one of the many choices. You will need a couple of details from the LED spec sheet and then the calculator will show you exactly what to buy.

[Coolspeedbot]

thanks Nick I'll give that calculator a look

[Coolspeedbot]

Looks like I need a 680 ohm resistor for a LED to run on a 4cell Lipo. Or 330 Ohm for 2 in parallel.