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HP 7475A Plotter: Vinyl Cutting, Poorly

Well, with a bit of ballast, that little unsupported blade actually did cut some vinyl:

HP 7475A knife stabilizer - big nut weight

HP 7475A knife stabilizer – big nut weight

That ugly nut adds 125 g to the pen holder’s 19±10 g (that’s the spec) down force and grossly overloads the pen-lift spring at the solenoid, but it did provide enough force to carve that little strip from the vinyl sheet. Vertical compliance comes from the pen holder’s travel, so the weight exerts a constant force at the knife tip.

I’m using the front-panel controls to drive the pen around at whatever speed the FAST button provides, which limits the results to straight lines.

The vinyl, leftover from a discarded window decoration, is 0.15 mm = 6 mil thick and definitely not intended for use with a cutter; vinyl cutter sheets and rolls seem to run around 0.07 mm = 3 mil.

Obviously, this doesn’t have much potential, but it actually worked better than I expected. The unguarded blade bites into the substrate (which I did expect), so the next step is to wrap a nose around the blade for controlled depth-of-cut.

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  1. #1 by Red County Pete on 2015-04-29 - 16:14

    Completely offtopic, but still:

    We just saw Phillips 8000 lumen/8.5 W (“60 Watt equivalent”) LED bulbs in twopacks for $4.97 the pair. The power supply is much smaller and lighter than the Crees that HD normally sells. They’re flagged as not dimmable, but that’s moot for most of my applications. We just installed 14 of the buggers, betting that cheapification wouldn’t clobber us. No heat sink and they’re a good fit for older fixtures.

    [/OT]

    Saw a Cricut paper cutter at Jo-Anne’s yesterday. Pretty beefy head rails. Mercifully, Julie is uninterested in such appliances. I’d consider something like the 9872 flatbed plotter for hacking, but I don’t know if it ever came with anything other than a GPIB interface.

    • #2 by Ed on 2015-04-29 - 16:40

      We just installed 14 of the buggers

      May the Force be with you.

      So far, our garage hasn’t blacked out and the living room torchieres still look good: LEDs might actually work!

  2. #3 by RL on 2015-04-30 - 10:15

    Those new Philips LEDs are attractive pricewise, but another downside to them is that they are not designed for use in enclosed fixtures. Also warrantied for only 10K hours. But at that price, maybe it doesn’t matter. Great for table lamps and such, but I never use anything as small as a 800 lumen bulb in a table lamp.

    • #4 by Red County Pete on 2015-04-30 - 16:13

      The CFLs are also “not for enclosed fixtures”, and are listed as 900 Lumen. (Think Sears HP–the LEDs are considerably brighter.) I’m betting on improved lifespan, since the kitchen wants 6 bulbs on at a time. using a ladder every 3-12 months was a pain, especially with our border collie. [woof woof woof!!!]

    • #5 by Red County Pete on 2015-04-30 - 21:35

      Looked at the LED package. They are silent on enclosed fixtures, though T_ambient_max is 45 C. (Min is -20 C). No firm idea of the thermal resistance of an enclosed fixture, but I’m guessing it’s Low Enough. [grin]