Help with disc

[ewan]

Help with disc

Disc (do you have MSN?)

[Guest]

Help with disc

Im not sure if Dominics drill mounts are suitable if youre only going to attach a single motor.

If Im not mistaken, there should be three small screws in the front of the drill motor.

My suggestion is that you use those screws to attach the motor to the 10 mm aluminum blocks (picture in my profile).

As the pully will be very small, the belt will probably slip every time you activate the disc. A chain would work much better!

In order to get a little more energy out of the disc, I would suggest that you actually exchange the disc for a drum. As you will then be able to increase the weight of the whole thing, and still keep the robot invertable/invertible.

If youre only going to use a single motor, then Id suggest that you overvolt it.

[team_ireland]

Help with disc

Or Ewan why not just use a gold motor or silver motor.

I think A Sliver motor would be almost perfect. Give a bit more power than just a drill motor

Regards
Ian

[ewan]

Help with disc

Im using a timing belt so slippage shouldnt be a problem. And Ill look into the aluminium mounts as being part of the motor mount also (thanks for the pic)... Im overvolting a 9.6v motor on 14.4v...

Ive been now thinking of using two 14mm steel discs bolted together, this would be an effective 28mm spinning steel mass. again 65mm diameter... And also milled out in the centre...

Ill release pics of the build soon... (on http://www.micro-maul.co.ukwww.micro-maul.co.uk) Oh and Geoff, When will your website be up?...

[ewan]

Help with disc

A silvers RPM is not anything close to a drill motors. A drill WILL gat a small disc, like the one I plan, Up to speed farely quickly...

[geoff]

Help with disc

Ewan,
Even if you make the disc 20mm wide then you only increse the KE to 180j (still not a lot!!)
If you have access to cnc facilities why not have them cut you, as Christian sugested, a rim biased drum
if you could get say 70 - 80% of the mass at the rim and a width of say 75mm your KE rises to around 0.61Kj @10000 RPM BUT you are looking at around 1.9Kg in weight!! The fundermental problem here is that your dia. of 65mm is too small to allow a reasonable rim speed and therefore an acceptable KE, unless you are going to run it at silly RPM!! +/- 17500!!
If you want my advice, I think you need to have a serious think if this really how you want to go on this bot.

Sorry I dont have an MSN id. I use Yahoo IM

[ewan]

Help with disc

This is just an add-on weapon, just something active to keep the robot exciting as it will be mounted up the wedge, the disc will have very mini teeth, just the nibble the opponents underbelly. I am not looking at anything OTT, and the weight I have remaining in the bot after the fully CNCd chassis is quite small...

[geoff]

Help with disc

Fair enough Ewan, just keep it SAFE!!

[Guest]

Help with disc

Actually, most drill motors does something about 20000 RPM at their rated voltage. So with a bit of overvolting, that speed is reachable!

[Guest]

Help with disc

Has anyone thought off using friction drive for disc weapons? I have used friction drive in 2 feather weight disc weapons. The first was in Hellbringers saw using a RS-540 (next size smaller then a drill motor) with a foam wheel giving a 2:1 ratio. It was only good at hitting coke bottles (6m up in the air) but the friction drive did make a good clutch.
My next robot, The Aggressor, used a RS-775 (next size up from a drill) with a 6:1 ratio onto a 12 inch bicycle wheel. The bike wheel made an awsome fly wheel and at the last event I bent the 5mm steel teeth 30 degrees back rather then the wheel deforming. It also hit our opponent 15cm into the air in the process too.
Anyway the motors are of the high speed kind and even with the light weight saw fixed between bearings and 2:1 ratio it wouldnt have hit 4000 rpm. Thats all I wanted to say.

[Guest]

Help with disc

Daniel, a friction drive usually contains a lot of resistance. When youre dealing with drill motors, thats exactly what you dont want.

Ewan, if you want this weapon to actually do some damage, then a drum is your only option.

Just buy a 65 mm steel tube of suitable lenght and thickness, then persuade your sponsor to weld a small disc to each side. Cheap, easy and very effective!

[ewan]

Help with disc

Seeing as an output of 20,000rpm is quite possible with this type of motor (when overvolted slightly), I have recalculated, using the http://www.teamcosmos.comwww.teamcosmos.com kinetic calculator, that even a tiny disc like this has 1705j of energy stored within it (this is when you take the energy with centre milled out to a smaller thickness...

[Guest]

Help with disc

As long as most of the weight is on the outer rim, then it should work fine.

But I still think you should mount the disc on the back. As your scoop still will be your main weapon, the disc will stall then every time you push your opponent.

So it will never actually reach the kind of speed youre hoping for, unless you mount the disc on the back!

Im not complaining on your design, these are just suggestions. If you manage to get that kind of energy, then it would be sad if you didnt use it properly!

[Guest]

Help with disc

What I was trying to point out is a motor will never hit its quoted top speed once there is a load on the motor. Even with the weight of the shaft of the motor itself will put a load on it and slow it down. We had a problem in Australia (and still do) with builders quoting blades and discs spinning at 12000 - 15000 rpm and blade tips speeds over 1000 km/h from simple drill motors. Im just trying to say be reasonable with your calculations.
And the bit about the friction drive was something Ive never heard any pommys talk about. I know I dont have problems with friction because with the motor is stationary the foam rubber wheel is 1mm away from the bike wheel and with the speed of the motor itll expand to meet it.

[Guest]

Help with disc

About 63% of the qouted top speed is reasonable.