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  1. #1
    Join Date
    Aug 2016
    Posts
    122

    Routing Plastic

    So far, all I have cut is wood and circuit boards (and part of an Al clamp, but don't tell anybody). I want to cut out a rectangle in a plastic cover (electrical box from Lowes - no idea what the material is). The cover is 4x4" and the rectangle is around 3x1 or so. I am mounting an LCD display in it to monitor AC power to the machine just for kicks. Anyway, I bought an Amana 1/8" O bit. Been reading about speeds and feeds, etc. Just thought I'd ask for tips before I go after it this weekend.

    Also, I have an acrylic award that is just the right size to use as a blank to make an edge finer (mill it into a try square shape and add metal faces) . Anybody ever cut up one of those clear awards with a floating logo inside, etc.?

    Thanks,

    Tony

  2. #2
    Join Date
    Jan 2011
    Posts
    188

    Re: Routing Plastic

    wall plates are often made of hard nylon or polycarbonate - that can gum up your bit real quick - so use a lubricant (or air), conservative feed rate and lower rpm - be ready to hit stop if anything sticks to the bit -

    electrical boxes are softer plastic like pvc and that can really gum up your bit

    I'd do a few shallow passes rather than cut all the way through at once - ramp the lead in and clamp it down good and it should be easy - just don't cut too deep or too fast

    I don't know about the thick acrylic - the best strategy depends on the dimensions and tooling
    www.signtorch.com

  3. #3
    Join Date
    Aug 2016
    Posts
    122

    Re: Routing Plastic

    It worked! This box is pretty soft. Alsmost soapy feeling. Ah, I just looked it up to give a link and Lowes says it is indeed PVC. I did a test cut within the area I wanted to remove. I used 65IPM and turned the Bosch down to 4ish. No issues. It cut right through like butter and no sticking, etc. I used ramping and 0.1" cut depth.

    Worked out very well. My monitor fit in the hole perfectly after I squared the corners and made some clearance for the tabs that hold it in. Got it all wired up and mounted on the wall. All I had time to do was vrify that it works. It seems to work quite well. Pics coming....

    The box -

    https://www.lowes.com/pd/CARLON-4-in...sition/3127463
    https://www.lowes.com/pd/CARLON-4-in...sition/3127463

    The monitor:

    Panel Meter, Snap-in, Multi Function AC Volts, 100Amps and 22KW | MPJA.COM

    Panel Meter, Snap-in, Multi Function AC Volts, 100Amps and 22KW | MPJA.COM



    Thanks,

    Tony

  4. #4
    Join Date
    Jan 2011
    Posts
    188

    Re: Routing Plastic

    nice - what is that wooden thing in the background?
    www.signtorch.com

  5. #5
    Join Date
    Aug 2016
    Posts
    122

    Re: Routing Plastic

    Ha! Well, hmmm, how to explain....it is a cuckoo clock bellows. Just a silly thing I made for fun. The crank turns a cam that raises and releases the bellows. The fisihing weights on top were "callibrated" to give the proper release. I'd like to make a nicer version with the CNC router and maybe even connect the crank to a stepper...wait a minute... is quickly becoming a digital cuckoo clock!?

  6. #6
    Join Date
    Mar 2011
    Posts
    61

    Re: Routing Plastic

    Confused - in the picture it shows 120v and .91a. That should equal 109.1 watts yet the readout shows 57.7 watts.

  7. #7
    Join Date
    Jan 2011
    Posts
    188

    Re: Routing Plastic

    Quote Originally Posted by kaetamer View Post
    Confused - in the picture it shows 120v and .91a. That should equal 109.1 watts yet the readout shows 57.7 watts.
    unlike DC - AC has a power factor to consider
    www.signtorch.com

  8. #8
    Join Date
    Mar 2011
    Posts
    61

    Re: Routing Plastic

    Point taken. Thanks for the clarification.

  9. #9
    Join Date
    Aug 2016
    Posts
    122

    Re: Routing Plastic

    Yeah, I'm not good at explaining (plus I'm an ME not a EE!), but I ran into all of that when building a fan controller that used the AC fan current as a trigger. I was trying to display the current draw. Using a coil around one leg, the voltage follows the current (sin wave pos/neg), so you have to force it to be positive around some base voltage, the do all the math (least squares and all that). Fortunately, I was only looking for a large delta in the current, so the absoute number was not critical. I think my number is still incorrect. But the AC fan draws a minimum of 6A (on low) and the idle draw of the board is around 150mA, so that is easy to see. This whole thing was to control an inline booster fan. I used an Arduino. Someday, I'll go back and figure out what is wrong with my numbers. They aren't off that much though. I compared it to a Kill-a-Watt measurement. I've even read that those aren't terribly accurate, but I haven't checked mine against a good meter. When I bought this reader, I read on several sites that it is fairly accurate.

    Tony

  10. #10
    Join Date
    Mar 2008
    Posts
    57

    Re: Routing Plastic

    Aye yae yae, a power factor of 60% is pretty bad, I think. For single phase loads. I'm a mechanic by trade, so please correct me if I am wrong. But what I've typically seen in the field is ratings closer to 70% on some of the crappier pieces of equipment, and closer to 80 - 90% on some of the better stuff. Is this suffering from being evaluated at the low power range of this AC router? That would potentially explain the terrible pf.

  11. #11
    Join Date
    Aug 2016
    Posts
    122

    Re: Routing Plastic

    I did some googling, but I still don't understand how to measure the power factor. Has something to do with looking at the phase angle between the current and the voltage? Beyond my level.... In the picture, the router wasn't on. Only the CNCRP box..

    Oh, yesterday, I did route the acrylic award that I asked about in the first post. It went pretty well. The finish is not good, but for this project I don't mind. I was juts happy that nothing broke or went soaring across the shop! It sounded a little rough, but no stickies and it just kept on cutting.and making snow! I fastened it down with double sided tape, swo it could have been moving a tiny bit. I'm using this piece for a corner edge locator jig thing. Sorry, no pics, but I'll take some - its ugly!

  12. #12
    Join Date
    Apr 2015
    Posts
    130

    Re: Routing Plastic

    Quote Originally Posted by SignTorch View Post
    unlike DC - AC has a power factor to consider
    Single phase ac induction motors always have a lagging power factor, meaning the current is lagging the voltage giving a PF reading of less than 1. To calculate the PF you would need accurate readings from you meters. You need to use a known accurate VA Meter to check your system.

    UPDATE: I looked up the specs on your meter; it displays Voltage, Current(in amps), Power (in watts- apparent power) and Energy in kWh (kilo watt hours). Unless the unit has a function to convert amps to True Power, which I seriously doubt, the watt reading is inaccurate.

  13. #13
    Join Date
    Aug 2016
    Posts
    122

    Re: Routing Plastic

    So, do you think they just use some approximate power factor value? Just curious how they come up with their numbers. Wonder how the Kill a Watt does it. Appears that it is not a trivial measurement. On the box that I made with the Arduino, the amps do match the Kill-a-Watt fairly close. I was never concerned about wattage. Interesting stuff, but I'm not sure I understand it yet (or perhaps never). Anyway, I wasn't expecting a whole lot for $14.95 anyway. Need to plug it into the Kill a Watt and see if they match just for kicks.

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