Re: belt drives GT vs HTD

After just a quick look:

Increase the 1/2" cross shaft diameter. Especially if X axis bearings
are precision linear ground style. I'd use a smaller stepper motor
and belt it 3:1 i.e. 750*3 = 2250 Less mass, cheaper drive. At high
accel/decel you'll need to key the pulleys to the shafts; with a
dual "captured belt drive you'll need a way to "time" one side to the
other. Conflicting requirements, you'll need to resolve. DON'T plan
on "setscrews" to hold this thing in alignment, IMO.

Gantry seems heavy. You didn't list travel size? But then you didn't
say how big the holes were? Or what type of tool is doing the
drilling? In what type of "wood"?

Lastly, my standard "don't use trapezoid timing belts!".

Hope this helps.

Ballendo

--- In CAD_CAM_EDM_DRO@y..., carlcnc@s... wrote:
> Okay,
> I need some input from someone who has done this or knows more
than
> I do [doesn't take much]
> I am building a point to point machine, was going for rack and
> pinion drive one side . Decided that this application would be a
good
> candidate for timing belt on both sides of X.
> Here's the skinny
> Total Gantry weight 175#, riding on bearings with .006 COe
> acceleration [desired] to max speed of 1000 ipm,?"sec/sec
> I am planning 1" 3/8 pitch GT "captured"or belt held each end.
> 1" pitch dia. 2100ozin stepper turning that connects to both sides
of
> X. shaft dia is 1/2 in.
> There is no cutting/sideload on Z as it is only for drilling thru
> holes in wood.
> Chart I have says a 1" GT belt is good for 184lbs. working force.
> Any one see a problem with this? Have I overlooked or under
> calculated anywhere?
>
> thanks
> CB