Team MedBots

[Max]

Re: Team MedBots

I know the brass valve is heavier and larger but a paintball valve wouldn't fit in the existing chassis :sad:
So does anyone know if it should fit?

[maddox10]

Re: Team MedBots

I know the brass valve is heavier and larger but a paintball valve wouldn't fit in the existing chassis :sad:
So does anyone know if it should fit?

Is the CO2 nut in the current setup solidly mounted in the chassis?

[Max]

Re: Team MedBots

No, but I need the valve to screw onto the trev reg at a 90 degree angle.

[maddox10]

Re: Team MedBots

Easely solved by putting a 90° angle paintball connection to the Trevor.

Oh well, in any case, it is possible to fit a RR screw valve on a 12oz paintball bottle. If the 20oz bottles provided are unmodified paintball bottles.

Otherwise it's a more involved process. But not rocket sdience nor CNC metalworking.

[Max]

Re: Team MedBots

Is there any difference between the motor on a 12v drill and a 9.6v drill?

[plargen]

Re: Team MedBots

the only real difference on the motor label of the 1s i have are the 2 different voltages dunno if there's a gearing difference

[Ellis]

Re: Team MedBots

Is there any difference between the motor on a 12v drill and a 9.6v drill?

Do you mean aside from the voltage difference? I don't think so. The output RPM when running their rated voltages might differ, I'd expect the 9.6v to be a little slower. Gearbox-wise, it is quite likely they're identical. That said I have never worked with 9.6v drills so hopefully someone who has will chime in. It may be that the reduced torque from the 9.6v allows the manufacturers to use slimmer gearwheels, or something.

[Max]

Re: Team MedBots

I meant the motor, I wasn't sure if the motor was the same just running on different voltages.

[ewan]

Re: Team MedBots

Gearboxes are almost always the same with cheap drills (inc. plastic first stage), the motors however are (most of the time) wound to give roughly the same power/speed output with the 9.6V at 9.6V as the 12V at 12V. Sometimes particularly cheap manufacturers will use a 9.6V motor at 12V or vice-versa though.

[Max]

Re: Team MedBots

I've started on the rebuild of centrifuge! This time the bar will be powered by a fan motor and it will be invertible without those castor wheels on top.
So far I have welded a frame and cut some hdpe panels:


It seems massive but now there will be plenty of room or the electronics. I will probably put some GR01s in there instead of the drill motors.

[james...venom]

Re: Team MedBots

Looks great so far! If I can point one thing out, one of the reasons I believe NST is so good is that Sam has tried to get the drive wheels as far forward as possible and it's made NST really controllable without a massive weight out the front. Having wheels right at the back is a bit like steering a heavy shopping trolley. Look forward to seeing it running!

[Max]

Re: Team MedBots

That's an interesting point- I might try to move things around to move the wheel further forward.

[sam_smith]

Re: Team MedBots

Its good to see another bar spinner on the build Max.

That is very good advice from James. The first NST had the wheels too far back and it struggled to turn in one direction when the disc was running. Bringing them forward with this type of design makes a big difference, the wheels in NST are only a few mm from the spinning bar.

[Max]

Re: Team MedBots

I've been thinking about hydraulics again and there is one thing I don't get- surely the hydraulic ram only has as much power as the motor that runs the pump so why would you bother with hydraulics rather than a linak or a high reduction gear box to power a crusher?

[maddox10]

Re: Team MedBots

Because with Hydraulics you can achive ratio's in the the 1000's to 1 in 1 go.

It's up to the builder to see how much power he wants to put in the system. But that's depending on what motor, and how far from the max efficiency the builder wants to go from the motor-power curve.

Basic formula:

pressure (bar)xflow (liter/minute)/500=Kw needed.

Example. we have a speed 900 drving the pump, with the max efficiency rating of 12V 13A=0.15 Kw

The most small , cheap gearpumps are in the 200 bar range.

(200*.45)/600=0.15

This give me a 0.075CC gearpump (each revolution is .075 cc*6000=0.45L/min) to be mated to the 6Krpm running Speed 900.
Unfortunatly, the smallest, affordable gearpump I ever had was a 0.17 CC=2.5 times to big. Easely solved with a reduction gearing. Pump will run 2400 rpm then.

Imagine a 50mm bore ram, stroke 100mm.
Power is 2.5*2.5*pi*200=3926 kg. Volume is 0.2 Liter

Flow is .45l/min. Filling that ram takes 27 seconds.

Half the pressure, and you can double up the flow.