Rules regarding diamond cutting blades?

[danny]

Hello

Can anyone clarify what the rules are for saw blades on featherweight robots? Are diamond blades such as this: http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=101156&ts=04174&id=72480#http://www.screwfix.com/app/sfd/cat/...4174&id=72480# allowed to be used?

Thanks
Danny

[geoff]

Rules regarding diamond cutting blades?

Hi there Danny, and welcome to the FRA forum.
The build rules prohibit the use of hardened steel blades because of the danger that they can shatter under a hard impact.
Providing that the body of that blade isnt made from hardened steel and you dont run it in excess of the maximum speed stamped on the blade, then subject to the blade mounting hub, shaft and bearing assembly being strong enough to hold everything down I dont see a problem.
As with any spinning weapon the mountings are CRITICAL they must be strong enough to not only to support the blade but also be strong enough to withstand any impacts of other machines or your machine against the arena side wall while your blade is at full speed!
Remember, if your machine comes apart in the arena the only thing that gets hurt is your pride.. If it comes apart in your garage...!!! So please be very carefull when you are building and testing.
Good luck with your building and above all BE SAFE.. One word of advice... if you are not sure of anything..come here and ASK first!! we are always happy to give advice.

[danny]

Rules regarding diamond cutting blades?

Hey, Thanks for your reply. How can I tell if the blades have been hardened or not? Any tell tale signs on the blade itself?

Also well im on about blades, Does anyone happen to know where I can get some v belts and extremly lightweight (maybe aluminium or maybe even some form of plastic) v pulleys from? (UK supplier would be best) (I dont want to use timing belts because I want the belt to slip if the blade snags.)

Thanks
Danny

[robjones]

Rules regarding diamond cutting blades?

I suggest you use the emergency fan belt material for a belt. (usually about £5 on ebay)Scrapyards have cheap supplies of v pulleys

[ewan]

Rules regarding diamond cutting blades?

Cant help you with the v-belts Im afraid, Ive always used timing belts (& pulleys) and never really had any problems (I prefer them to chains as they do allow some slack - the belts arent rock solid - and they are usually lighter). It would be good to know what kind of set-up youre looking at running (i.e. what motor and reduction etc) for the weapon.

Had a look on your site, looks like youve been busy with robot stuff for a long while now. Good luck with it, and please ask us if youve any queries at all.

Ewan

[danny]

Rules regarding diamond cutting blades?

Rob, Thanks for the suggetion, I searched ebay and found this: http://cgi.ebay.co.uk/EMERGENCY-REPLACEMENT-FAN-BELT-ANY-CAR_W0QQitemZ4633440741QQcategoryZ36631QQssPageNam eZWDVWQQrdZ1QQcmdZViewItemhttp://cgi.ebay.co.uk/EMERGENCY-REPL...temZ4633440741 QQcategoryZ36631QQssPageNameZWDVWQQrdZ1QQcmdZViewI tem

I personally wouldnt trust that end to end fitting. I would rather use a normal v belt with some form of tensioner (if needed)

Ewan, I havnt sorted any of the ratios or motors yet, Im in need of a very light weapon motor. I havnt googled for anything yet other then pulleys and belts. I believe a mains angle grinder has a no load speed of 10,000 - 11,000 rpm, im not going to achieve anything near this, Dewalt have an 18v cordless angle grinder that has a no load speed of 7000rpm. I guess I would be lucky to achieve anything more then 4000rpm. Do you have any suggestions of a motor? (Power supply is 12v max) Bear in mind I need the lightest possible configuration (sp?)

Thanks
Danny

[aliboy]

Rules regarding diamond cutting blades?

Some form of a car radiator fan motor would be a good choice , nice flat and some can get some ridiculous speeds out of them .

[robotic_ants]

Rules regarding diamond cutting blades?

I think it also depends on the weapon motor you are using as well at the situation. On my first bot I used a timing belt because for one I wanted the weapon to keep spinning when it meet resistance also it does have abit of give against shock impacts. The motor I was using at the time was an Gold Motor so I wasnt worried about damage caused by shock and stall conditions and it worked flawlessly.

Although in my new bot I used v-belt because with it is powered by an Ev Warrior and I want to preserve it. With a v-belt it means I can avoid sudden shock loads and also preventing the Ev Warrior from stalling. Avoiding stalling the motor also stops it from demanding fatally high amps.

Chris - ^_^

[ewan]

Rules regarding diamond cutting blades?

Firstly, seeing as youre probably going to be using some kind of cutting disc, find the rated rpm of the disc so that you can get an idea for what kind of rpm motor you should be after.

http://www.toolstation.com/shop/Blad...20/sd2586Heres

[robotic_ants]

Rules regarding diamond cutting blades?

Well for weapon motor also look at the price because the cordless Dewalt cordless angle grinder is going to cost quite abit because it is a professional tool. The kind of motors you want to be considering are car fan motors or the similar Ev warrior although they are fairly heavy, gold motor about midrange in weight, HTI or Speed 700+ motors small and light.

Chris - ^_^

[danny]

Rules regarding diamond cutting blades?

Chris, Im not planning on useing the dewalt angle grinder, I was just comparing the speed of it, sorry i didnt make myself quite clear. The weight limit is so tight on this build.. ive got to try and get the weapon motor, the blade, the belts and pulleys into about 1KG 1.5KG MAX. The blade is going to be of the 4 1/2 size. Chain would simply be too heavy.

[typhoon_driver]

Rules regarding diamond cutting blades?

you can get v belts and pulleys from RS components

http://rswww.com/cgi-bin/bv/rswww/browse.do?catoid=-1600746048&cacheID=uknetscapehttp://rswww.com/cgi-bin/bv/rswww/br...heID=uknetscap e

Can be rather pricy but you get what you want fast. I wouldnt discount V belts. We used them on the typhoon bots from 12kg to 50kg. Were very good at transfering power and did allow an amount of slip when the discs were stopped for any reason.