Re: [CAD_CAM_EDM_DRO] Re: [DIY-CNC] need transmission ideas / advice re: gantry

Can't you set up counterweights? Springs would probably be a bad idea
because of the potential energy stored when stretched

Counterweights are not to be sneezed at, and are used in larger machines. No
need to waste energy lifting deadweight .

Regards
Roland


2009/5/11 gcode fi (hanermo) <yahoog@...>

>
> I am making a large cnc-driven gantry, which is done.(4.4 m wide, 4 m
> lift, 8 m rails).
> At the last moment, I ran into some difficulties at the transmission;
> 2-stage, HTD 5 mm 15 mm wide steel pulleys and timing belts, 1:3 to 1:3 for
> 1:9 total.
>
> I have no way to get electricity to the site, we run from 2 large
> batteries of 12 V DC (200 amp hours each).
>
> I am using a DC treadmill motor, from surplus center, rated upto 2.5 HP
> and 130 V DC.
> Unfortunately, the motor seems to be too weak on torque !
>
> Any ideas on how to move the gantry ?
>
> The gantry and payload are 300 kg in mass, its a rolling non-dragging
> application, up a steep gradient of 45 degrees, 8 m length, total lift 4 m.
> In effect, I need to roll a big ball up the hill.
> I only need about 20 lifts per charge or per day, no great hurry.
> Precision is unimportant.
>
> I built steel guide rails (V-rails and rollers), which work ok. The
> gantry runs on the V-rollers.
> For tests I have been directly connecting the motor to the batteries- I
> have a spare G320 and encoders on hand if I need them.
>
> Now, it seems that;
> As the motor is rated at 6000 RPM at 130 V DC (18.5 amps), at 24 its
> only maybe able to generate 0,46 HP or around 300 watts ?
> Any ideas ?
>
> Find a trailer hitch, car-fender puller/tow or something for parts ?
> Could I make / use a boost up transformer to go from 24 to 80 V ?
>
> I am considering taking a 6" rotary table and hooking it up to the
> treadmill motor.
> The transmission would go from 1:9 to 1:40 ... and would be slower and
> stronger.
>
> Comments ?
> I am in a hurry, I must get this working this week, so cannot order
> parts from the US.
> I am in Barcelona, Spain. I am trying to spend under 400$ or 300�.
>
>
>
>
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