The problem with feeding bare copperclad is that it has to bridge two
of the knurled sections, so a large piece is required each time I
think I am getting excellent back and forth feed by using two o rings
on the top shaft, opposite the two knurled sections on the right. You
are right, however, that the rubber does not help since it is the
bottom roller that does all the work. Perhaps I'll put the plastic
back on. A nice mod would be to have the whole length of the bottom
roller textured so the copperclad could be any size.
Hmmm, the top roller is spring loaded, so an easier approach might
be to use larger diameter plastic rollers on the top roller opposite
the textured areas, and use a thin, fixed size carrier. The
copperclad then sits on the carrier, held by double stick or even
registration pins, which would make double sided a snap. You could
even put in guide rails on each side.
If you are going to route the traces, I think some work has to be
done on the Z axis. Perhaps a stronger return spring and a LOT more
current through the solenoid. I think the dremel is fine for drilling
holes, but I'm not too keen on it for milling traces. Perhaps this
motor would be better
<
http://www.amazon.com/Spindle-Zen-Toolworks-Machine-Holders/dp/B0039HCK6S>,
though it is $90 USD.
I like this machine as a reasonably well constructed XY table. It
could be used as a laser cutter, a plotter, pcb drill, light duty
router, etc; I think it might do better by converting it to a
standard cnc using Mach3 or some free software, but it's pretty neat
as it is! BTW, here is a datasheet on the PM42S-096 steppers it uses
<
http://www.nmbtc.com/motors/part-numbers/Permanent-Magnet-Stepper-3.75-degree/PM42S-096/4864>.
Mark
At 12:43 PM 9/15/2012, you wrote:
>Great topics!
>
>One thing to know is that the Z-axis is just a solenoid with a
>spring return. A solenoid's force (-Z in this example) is
>proportional the the electrical power applied and how clost the soft
>iron slug (armature) is to the end of travel. This last I believe
>varies as the square of the penetration distance so the further you
>can get the slug to penetrate the solenoid, the higher the force. I
>measured between 4 and 7 volts on the solenoid, depending on
>"Thickness" selected. If you raise the inserted holder (be it for
>the swivel blade, pen, Dremel extension handpiece, etc), the
>downward force will increase until the solenoid bottoms out - with a
>metallic 'click'.
>
>Not sure what's hanging up in your machine to cause it to skew.
>Obviously something mechanica I'd guessl. In my hopefully educated
>opinion, I would NOT remove the plastic rollers as
>rubber/elastomeric ones will not exert enough pressure on the PCB.
>Also, of the two metal rods that pinch the PCB, ONLY the bottom one
>is driven so you will get little/no torque/force out of the top one
>or anything you mount to it. The downward spring tension on the top
>metal rod and rollers, pushing the PCB into the bottom metal rod's
>knurling (grooves), is plenty to grab the material, IMHO. The
>purpose of this assembly is to force the material against the
>knurling on the bottom metal rod, the only thing transfering force
>to the material. Chosing "Enhanced Cut" will roll the PCB in and out
>(Y direction) wo hopefully wear a grooved path in the bottom of the
>material for additional friction. I have not needed this in the
>past. The copperclad against the grooves in the metal rollers gives
>you the best non-slip friction possible, in my opinion. I believe
>rubber will encourage slipping.
>
>I think on my web site, I recommend 0.5 oz copperclad or thinner. I
>have had difficulty cutting through 1.0 Oz. I think Digikey sells
>this. Try Think and Tinker as a source for high speed carbide
>router, mill and drill bits. For the milling bits, I've had good
>results with the 30 deg ones. If you're trying the swivel knife
>approach, by all means go the 3rd party carbide blade route as the
>standard steel ones will wear out quickly. I have also found a
>source for paper backed copperclad instead of fiberglass, possibly
>extending the life of the blade. More later.
>
>I have tried converting the Gerber 274x files to svg and purchased
>the Designer Pro addition of the software but I'm not sure this is
>required as I'm getting great results with their raster-to-vector
>TRACE app included. I'd like to hear more if you get better results.
>Also, I've learned from Silhouette Support that very closely spaced
>vector objects are drawn as one, possibly compromising small traces.
>This normally doesn't affect paper cutting other than being able to
>cut a lot faster through highly detailed, closely spaced
>vectors. They have offered to make a firmware change for "us". What
>a great support team!
>
>Mike
>
> >I just received my Sillhoute Cameo and have a few first impressions.
> >Mike, if you could chime in here I'd appreciate it because I can't
> >seem to achieve your results.
> >
> >1 - I cannot get a pcb to track through the machine accurately. The
> >cutter seems to hang the board up so that it feeds irregularly,
> >skewing sideways back and forth as it goes in and out of the machine.
> >This seems to be true whatever speed I select.
> >
> >2 - Most of the tracks I get are not completely through the copper. I
> >am using the highest setting on the cutter.
> >
> >I am using Gerbv to convert gerber files to svg, then importing the
> >svg files using the "Designer Edition" of the Sillhoute software. It
> >seems to work well, but the feed problems make it hard to tell if
> >everything is accurate. I ordered a pen holder for the machine, so I
> >should be able to use it as a plotter to see exactly what is happening.
> >
> >The machine looks like it would be very easy to modify to feed copper
> >clad reliably. All it should take is putting a few o rings on the
> >shaft for friction and removing the plastic rollers. Hopefully I'll
> >have time to take it apart over the weekend.
> >
> >Mark
>
>
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>
>
>
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