nicholas.seward Wrote:
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> @Efxjim. The print head stays true as is. The
> geometry dictates that. The offsets on the
> central hub could be removed but it would increase
> the complexity and slightly reduce the rigidity.
> Additionally, software can make the adjustments
> for the offsets with some simple addition.
Precisely. This was one of the debates we had early on. Where small changes to software can make the hardware better, it's worthwhile.
nicholas.seward Wrote:
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> mofosyne Wrote:
> --------------------------------------------------
> -----
> > Btw I noticed you have motors on the arm
> itself,
> > don't you want to keep the weight of the arms
> > down, by relocating the motor elsewhere?
>
> I put them on the arm for simplicity of build.
> They ended up not being a problem. I estimate
> that I can get a faster nimbler bot if I replace
> the steppers with NEMA14's instead of NEMA17's.
> It is an interesting problem. I have more than
> enough power but the acceleration has to be
> limited because of all the arm inertia. A NEMA14
> has 1/3 the power and 1/3 the weight which should
> allow for a higher acceleration setting.
The routing of the drive cables becomes more complex if the motors are not mounted on the arm. This is one situation where updating the software to compensate for making the hardware higher performance would likely not work well: the hardware complexity for moving the motor off of the arm is bad.
-------------------------------------------------------
> @Efxjim. The print head stays true as is. The
> geometry dictates that. The offsets on the
> central hub could be removed but it would increase
> the complexity and slightly reduce the rigidity.
> Additionally, software can make the adjustments
> for the offsets with some simple addition.
Precisely. This was one of the debates we had early on. Where small changes to software can make the hardware better, it's worthwhile.
nicholas.seward Wrote:
-------------------------------------------------------
> mofosyne Wrote:
> --------------------------------------------------
> -----
> > Btw I noticed you have motors on the arm
> itself,
> > don't you want to keep the weight of the arms
> > down, by relocating the motor elsewhere?
>
> I put them on the arm for simplicity of build.
> They ended up not being a problem. I estimate
> that I can get a faster nimbler bot if I replace
> the steppers with NEMA14's instead of NEMA17's.
> It is an interesting problem. I have more than
> enough power but the acceleration has to be
> limited because of all the arm inertia. A NEMA14
> has 1/3 the power and 1/3 the weight which should
> allow for a higher acceleration setting.
The routing of the drive cables becomes more complex if the motors are not mounted on the arm. This is one situation where updating the software to compensate for making the hardware higher performance would likely not work well: the hardware complexity for moving the motor off of the arm is bad.