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  1. #1471

    Join Date
    May 2017


    Quote Originally Posted by dkj4linux View Post
    Alright! Several of you have already spoken up so here's the post with all the links I promised and a bit more information about both my foam cutter and the CNC machines I've used during its most recent development. I've been using this method for several years now to machine-cut my planes out of fanfold foam insulation sheet and DollarTree foamboard. Never again will I hand-cut designs. I know it appears a bit crude but I have cleanly cut "miles" of foam using this method with minimal fuss.

    Basically my foam cutter is a very fast reciprocating needle... like a sewing machine. The needle is formed from a length of 0.025" music-wire and attached to a small ball-bearing mounted eccentrically on the flywheel. The flywheel is mounted on the shaft of a 2826/2822 brushless motor (with ESC and servo tester) and spun at 8000-10000 rpm, resulting in a stroke/perforation per revolution. A feed rate of 600-1000 mm/min yields 10-15 strokes/mm and cleanly cuts DollarTree foam board (paper on), blue-cor fanfold foam, etc.

    In the past couple of months, I have built three of Ryan "Allted" Zellars' fantastic Mostly Printed CNC (MPCNC) machines for myself and a couple of friends and it is the perfect vehicle to mount a foam cutter and cut sheet foam materials (DTF, blue-cor FFF) accurately and cleanly. The foam cutter itself can be built and adapted to your CNC machine for less than $20 worth of parts (less if you're a scrounger). But if you also need a CNC machine -- and if you (or a friend) are "handy" and could tackle a large erector set project -- you can build a complete 48"x48" (or smaller/larger) MPCNC and foam cutter for less than $500 (<$300 if you can 3d print) and a weekend or two worth of time. It is easily IMHO the most flexible and economical way to get into CNC at the current time -- even if you have to buy the hardware and plastic "bundles" from Ryan's website. I'm not at all affiliated with Ryan or MPCNC... I'm simply an old retired engineer who appreciates good engineering when he sees it.

    If you are interested in building one (or all) of these for yourself, please check out the links below. I'll continue to monitor this thread, answer questions, and further interact with folks here but rather than repeating everything I'm providing links to threads/sites that deal with the active design/development of this foam cutter and Mostly Printed CNC. Please check them out.

    Foam Cutter design/development --

    A fairly lengthy thread featuring brushed-/brushless-motor versions of the foam cutter, a Mostly Printed CNC (MPCNC) build log, user build(s), and general DTF cutting thoughts:

    User build(s) and further needle guide development:

    Universal MPCNC quick change/release system for assorted tools (including foam cutter) and user build(s):

    All 3d-printed versions/parts --

    Brushed motor versions:

    Brushless-motor versions:

    Universal MPCNC mounting system, including foam cutter head:

    Mostly Printed CNC:


    Please feel free to join in the conversation and/or ask questions.

    -- David Johnson (aka "dkj4linux")
    can i just attach a pen and draw the plans with it ?

  2. #1472
    dkj4linux's Avatar
    Join Date
    Jan 2016
    East Texas, USA
    Quote Originally Posted by skymaster View Post
    can i just attach a pen and draw the plans with it ?

  3. #1473
    Posted a thousand or more times jhitesma's Avatar
    Join Date
    Mar 2012
    Yuma, AZ
    I should probably post this somewhere more obvious anticipation of the eclipse on Monday (which we'll only get 60% coverage on ) I build a solar viewer out of DTFB today.

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    More details later...but...onshape project for sketches to use for cutting:

    It uses the lens from a pair of +2 reading glasses from dollar tree as the primary. The other lens is a 2x barlow from my daughters telescope, that's the one thing that may be hard to come up with on short notice - sorry about that. If you're in or near a big city you may be able to find one at a camera store or telescope shop if you have one. This one was about $16 off amazon last summer when I bought it for her.

    All just really simple DTFB construction. The support rail is an experimental airlines style fuselage tube I had on hand...but I'm going to make something sized more like the tube on an FT Explorer and some matching collars under the lens holders to make it easier to use. I also need to lengthen the rail. Right now it only gives about a 1" view of the sun...but with a longer rail it can give an almost 3" image. ( tested that just holding things in the air - but didn't have enough hands to get a photo of that setup!

    Could all be cut by hand...but I wanted the barlow held securely and I suck at cutting circles by hand So just ran it all on the MPCNC...took 5 minutes to cut so probably quicker than I could have done it by hand.

    Tonight I'll build a better rail and focusing setup. Fingers crossed her teacher allows it....I meant to ask her on Friday but wanted a working prototype before I asked and didn't have a chance to pick up the reading glasses until today.

    Note - you can also do it without the barlow and just +1 or +2 lenses but you won't get as big of an image. Lot more details on other approaches to building one here:
    Stop in and say hi in the unofficial FT IRC channel!

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