[emorning]

Hi All,

Last week I finished building my first CNC machine and it cuts more poorly than I expected. When I use the machine to draw with a pen I get perfect results, but it can't cut .25" plywood well at all.
It has a 3'x3' cutting area and is built out of conduit pipes and 1x4's - so I knew not to expect much. Anyway, there are a lot of improvements I can make to this machine (for instance, I could replace the stretchy plastic tubing that I used to connect the stepper motors to the lead screws, I could use iron pipe instead of conduit, my z axis is too far from the z gantry, etc).
However, it occurred to me that an inexpensive position feedback system would be a better way to improve a low-end DIY machine. I'm thinking of some kind of sensor(s) attached to the spindle that can track the relative position of the spindle. Software would then be able to keep the spindle on track.

But first... does anyone know of any such existing feedback system? Or DIY implementations?

Thanks...
-ted

[ger21]

If it existed, it would cost far more than the rest of your machine. The answer, is to build a better machine.

My router uses conduit skate bearings, mdf and plywood and cut's very good, as long as I stay within it's limitations.

[microcarve]

Hi All,

Last week I finished building my first CNC machine and it cuts more poorly than I expected. When I use the machine to draw with a pen I get perfect results, but it can't cut .25" plywood well at all.
It has a 3'x3' cutting area and is built out of conduit pipes and 1x4's - so I knew not to expect much. Anyway, there are a lot of improvements I can make to this machine (for instance, I could replace the stretchy plastic tubing that I used to connect the stepper motors to the lead screws, I could use iron pipe instead of conduit, my z axis is too far from the z gantry, etc).
However, it occurred to me that an inexpensive position feedback system would be a better way to improve a low-end DIY machine. I'm thinking of some kind of sensor(s) attached to the spindle that can track the relative position of the spindle. Software would then be able to keep the spindle on track.

But first... does anyone know of any such existing feedback system? Or DIY implementations?

Thanks...
-ted

Your machine may be working far better than you're thinking if using
a pen gives you good results....

Reason is, there's very little forces involved with drawing with a pen
or marker, but with those rubber tubing couplings, then you need
a little force to push the router thru wood. The rubber tubes can & will
twist and flex as far as possible. Giving you some very wobbly results.

I used those vacuum tube couplings on my very first machine and it took
days of head-scratching to figure out how much trouble they were
causing me. My pen drawings were coming out great too....

May be only a 50% improvement by replacing them with more solid
couplings, but it's a solid start to trouble shooting...


John

[emorning]

Hi John,

Hey - that's good news about the coupler.
I'll make the easy changes to my machine before I go off the deep end :-)

thanks,
-ted

[mlabruyere]

I've been beat to the punch but I would also recommend going with something like LoveJoy fittings. They are pretty cheap but are stable enough for most wood cutting needs.

My first CNC used automotive hose with hose clamps....worked OK until I pushed a little too much....then the circles were ovals and squares were....well not square....