Joined: 30 Aug 2005
Posts: 2729
Location: Gold Coast
The closest thing you will find would be road profiler tips or tub grinder bits. The road profiler tips, which make those lovely score marks in roads, usually have tungsten carbide tips and tub grinder bits, used to mulch tree stumps, usually weigh about 500g each for a light one. If you want to buy that sort of thing you need to buy at least 100 at a time. Consumable castings arn't really good for robots unless you know where to find rejects, and I havn't found any small ones yet.
Thats why I designed my own water cut version.
Fri May 19, 2006 8:37 am
Valen Experienced Roboteer
Joined: 07 Jul 2004
Posts: 4436
Location: Sydney
carbide is pretty brittle though (from what i've seen), it will chip off i'd think (when it gets a good solid hit in on the wall say)
could be good if you can get it to "self sharpen" but apart from that... _________________ Mechanical engineers build weapons, civil engineers build targets
Fri May 19, 2006 10:14 am
Daniel Experienced Roboteer
Joined: 30 Aug 2005
Posts: 2729
Location: Gold Coast
Well the guys that spend all the money to stick the tungsten carbide on their road profiling tips don't seem to complain. But then again roads might be softer then I think since I have a tungsten tipped tree grinder bit here that had a rock get into the machine and pretty much caused the tip to explode.
I was thinking tool steel myself.
Fri May 19, 2006 11:26 am
Totaly_Recycled Experienced Roboteer
Joined: 15 Jun 2004
Posts: 1346
i would go with a tool steel or spring steel that could be anealed then driled then re- hardend
car springs are a good source of re-temerable?(spelling ) steel the blacksmiths at a place i worked used to make pick heads and crow bar tips for people out of them you can buy tool steel in bar or flat that can be worked then hardened for makeing chisels and things from .
Fri May 19, 2006 11:51 am
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
You could probably get car leaf springs from PnP cheaply. They could be drilled with cobalt HSS drills or carbide drills without annealing - you wouldn't get much life from an ordinary HSS bit. You could probably cut a tooth profile with an angle grinder, then carefully grind back the heat affected zone on a bench grinder. It would be worth going to PnP & getting a spring from a 4WD just to see what they charge... _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Fri May 19, 2006 12:08 pm
Valen Experienced Roboteer
Joined: 07 Jul 2004
Posts: 4436
Location: Sydney
They are going for abrasion resistance, not impact.
Sandpaper is very resistant to abrasion, you can "cut" steel with the stuff, you can tear it in half with your hands though.
thats what i was saying about brittle, its strong yes, but its not tough. _________________ Mechanical engineers build weapons, civil engineers build targets
Fri May 19, 2006 11:58 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
What do you think about car springs? It's not tool steel by a long shot, but if a leaf spring cost around $15 from PnP and you could cut around ten teeth (at least) from it, then it's a bargain! _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Sat May 20, 2006 12:56 am
Glen Experienced Roboteer
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
that would work well, but do the springs flatten out when you unbolt them all or do they retain their curved profile _________________ www.demon50s.com - Minimoto parts
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Sat May 20, 2006 1:02 am
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
Good question, I would guess the shorter bottom springs might almost flatten out but not the full length ones. For short lengths needed for teeth, a tiny bit of curvature probably isn't going to matter. _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Sat May 20, 2006 1:06 am
Glen Experienced Roboteer
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
finally got both wheel slots cut out and one drive attached. i need to grind out the wheel slots on the front but aside from that the tolerances are pretty tight. about 5mm on either side. good stuff. _________________ www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz
Sat May 20, 2006 8:27 pm
Glen Experienced Roboteer
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
Looks good glen iff you have any spare weight i would sugest putting a couple of angled pieces on the front near the blade as well so you dont have that square edde exposed
Fri May 26, 2006 7:44 am
Glen Experienced Roboteer
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
well well aaron produced a good idea for once xD so i think ill take that and run with it as its solved a hell of alot of problems!!
firstly im going to put that thicker box section on the front. so the front will be pretty well totally covered up. nice and armoured
no space for pullies? that is correct because im now going to use a pair of mini EVs to power it that sit up the front and power the outer rim of the flywheel friction drive. i believe the calculated speed is about 7500rpm so lets assume 4000 and thats good enough for me
this also means i can knock it down to 12v power and half the weight in batteries meaning more armour! and more space inside to play with which is a god send. and spare batteries too.
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