you wouldn't happen to know the density of HPDE?
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you wouldn't happen to know the density of HPDE?
About 970 kg/m^3, just less than water.
thanks Rory
Ok so I did the Maths and looks I might have to use HPDE in select places instead of Hardox. I knew this might have been the case but still a little disappointed.
You could always try thinner hardox. 5mm is really quite thick for a featherweight, especially all over. Carbide has 5mm hardox side armour and a 3mm raex base, and that's a heavyweight.
Hummm, might look into it but I can only go 1 or 2mm thiner at best.
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.
you wont get 1mm or 2mm hardox
SSAB did a run of 2mm but that was it, really just beetleweight stuff
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?
Attachment 6715
Yes. It's a huuuuuge pain when you have to enlarge the holes yourself.
thats why I wanted to be sure.Quote:
Originally Posted by R9000
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.
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.
I see, well looks like I made everything 0.5mm too big from you guys have said.
Its not a big deal unless you are using soft material or really crappy screws :)
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).
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?
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.
thanks Nick I'll give that calculator a look
Looks like I need a 680 ohm resistor for a LED to run on a 4cell Lipo. Or 330 Ohm for 2 in parallel.
Personally I'd run it off your 5V BEC. You'd only need something like a 100 Ohm res for that.
I thought you couldn't do that cause if the ESC messes up and the BEC stops working, the light will stop lighting. it had to be getting it's power from the battery but not through any of the electronics like ESCs and receiver.Quote:
Originally Posted by R9000
Yep, needs to come straight off the main battery supply after the link and not through any circuitry.
One option is to run a few LEDs in series to drop the voltage. In Coyote, I used off the shelf 12V LEDs but was running the robot on 6S/22.2V. Wired up in series, they each see 11.1V which is plenty to illuminate them. Saves faffing about with resistors and such.
Ok, I think I understand how that works, but i'll try the resister first.Quote:
Originally Posted by RogueTwoRobots
Ah, I didn't know that. My bad.Quote:
Originally Posted by RogueTwoRobots
didn't nobody notice during the tech check at extreme robots?Quote:
Originally Posted by R9000
What about the light on a sabretooth board? it turns off when there's no power and ready to run out the box. Alternatively, you could put the LED in the removable link, I would be interesting and easy to check if it's in or not.
There wasn't really anyone doing tech checks for the featherweights, at least not thorough ones. David looked over mine quickly, hence why I added the locking bar for the Sunday. He must not have seen where the LED was connected, after all you can't notice everything. Anyway, it was never a problem. I'll fix it for next time.Quote:
Originally Posted by Coolspeedbot
You can't put the LED in the link itself, as the link generally only completes the circuit on the positive wire, whereas the LED needs a positive and negative connection. Unless of course you run a double pole link that breaks both positive and negative lines, but that's extremely uncommon.
As far as I know, using the LED on a controller such as a Sabretooth is also not permitted. If the Sabretooth loses power or the LED breaks in battle, there's no indication to show that it's on, but the robot could still be fully armed. That said, the same could happen with a standalone LED, but it's easier to mount them where they're clearly visible. A Sabretooth's LED may not be bright enough to be visible either, unless it's mounted close to or nearby a see-through panel, which puts it at risk of receiving battle damage. And it's much cheaper to replace an LED than a pricey speed controller.
bit off topic but does the removable link have to on the positive side as it doesn't state in the build rules one way or the other in the build rules unless I missed a bit or is it simply preferred to be on that side.
Either side will do - I think its just a psychological thing to put the link on the positive side :)
Its common place to place it (or any switches) in the positive side otherwise your circuitry could be positively powered and a misplaced spanner or broken chasis connecting some electronics/frame to 0v on the battery could still mean the circuit is live.Quote:
Originally Posted by Maxamuslead
couldn't completing the circuit happen on either positive or negative ?Quote:
Originally Posted by Roboteernat
Strange, i have always be taught to connect a the negative last on stuff e.g. jump leadsQuote:
Originally Posted by overkill
Yes, disconect negative side last allows to 'discharge'?!
but yes could happen either positive or neg but your more likely going to have a connection made after your electronics than before, meaning you could blow us stuff unintentionally.
(your electronics are still live sided with the removable link on the negative side)
great thanks, this will also make it easier wire up my system =DQuote:
Originally Posted by Roboteernat
Did some rewiring, managed to use the housing for the fuse holder to make changing fuse easier.
https://68.media.tumblr.com/577528da...f23o1_1280.jpg
I also made a second removable link with a shorter wire to neaten it and stop it sticking out so far from its insert slot.
https://68.media.tumblr.com/cd37e2b8...f23o2_1280.jpg
Power light fitted and works (might change the colour), Wolf-E now complies fully with FRA regulations. Baring any faults Wolf-E is finished electronic wise. Did a full arming test, removable link works, power works, motors work, ESCs work, receiver works.
https://68.media.tumblr.com/6482b727...f23o1_1280.jpg
looking good
thanks