LowRider-inspired Foam Ripper

jhitesma · September 4, 2018, 4:24pm

Hey guys, been rather out of the loop lately (See my post on David’s thread over at FT if you want the details - it’s kind of personal and pretty gut wrenching so you’ve been warned.)

Anyway - I just had to chime in that I wouldn’t recommend a nutball as a first build. It’s easy…and it was my first…but…it doesn’t really fly like a normal plane and can be tricky to get the hang of.

The FT Flyer is a better starting point IMHO. But even better would be the mini scout or tiny trainer. They’re slightly more complex builds but fly MUCH better. The mini scout is probably my all time favorite plane. I’ve gone through 3 wings on mine and the fuselage is starting to fall apart - but I it’s just a joy to fly. Uses cheap parts (I have an 1806 quad motor in mine that runs about $10 along with a $8 ESC and $5 Radio…toss in 2 cheap ($3 or so) servos and you’re set.) It also uses small 500mah batteries which are a lot cheaper to stock up on than the bigger batteries larger planes need.

I even strap little all-in-one camera/vtx on the top and fly it FPV sometimes. Barnstorming the picnic shelters at the local parks is a blast as long as no one else is there

My Scout’s first flight (almost 4 years ago…not bad for a $1 airframe!)

And a year ago doing a little FPV with it:

jeffeb3 · September 4, 2018, 4:36pm

Wow Jason, that is incredibly sad. I am so sorry for your loss. I feel for you and your daughter and I can’t imagine how that feels. Just know we’re here for you, however we can be.

Thanks for the tips about those planes. I’m going to have to get back into these planes.

h0m3r2000 · September 5, 2018, 6:52pm

Jason, I am so very sorry for your loss. My wife has had surgery on her thyroid also and they made it sound so minor and I guess in her case it was. I also have a daughter and a two month old boy, I just can’t imagine not having my wife. Again I’m so sorry for you loss.

Mike

dkj4linux · September 7, 2018, 6:43am

Okay… it’s all good

Finally got FoamRipper in shape to cut those three sheets of DTFB for the vacuum pad… and things went quite well. No interrupts or squirrely things happened and all three sheets were completed and look reasonable.

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Here are videos (turn down the sound!) showing the needle cutter in action… cutting the slots and holes in three sheets of DTFB.

First, the vertical slots…also note the cable support that flexes while still holding the cables clear of the workpiece… one of those giant nylon cable ties from the hardware store

then the horizontal slots…

and finally the grid of holes…

I decided Elmer’s school stick glue (goes on purple!) from the dollar store would probably work fine for what we’re doing here so glued the two slotted layers together and weighted them down while they dried… while I watched the golf tournament. They seemed reasonably flat, after golf, so cut the 5 ports to receive the 5 ends of Mark’s plenum. I really wasn’t sure I needed to glue the hole grid sheet and decided to try without glue… it’s also the spoilboard, remember, so it’ll eventually be replaced with a new sheet at some point down the road. Also decided to forego a frame of any sort at this point… I’d like this to be the minimalist version.

The three cut sheets… the slotted sheets are the two bottom layers with holes on top…

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Mark’s vacuum fitting, a fun and impressive print…

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So, here it is in action. Spotted the hairy gorilla in the yard and called him in to help out… he did better, with supervision, but he’s still a crappy actor. Go Navy!

There it is… $3 worth of foam board and a printed vacuum fitting. And, it sucks! Hopefully the shop vac – a small 2.5 gallon unit – will not overheat with the restricted air flow in the time it takes to cut a sheet. I guess that’s the next on the agenda for testing… actually cut a plane and see how it does. Since Jason is fond of the FT MIni-Scout… maybe that would be a good one to try

– David

dkj4linux · March 10, 2019, 2:17pm

I’ve moved the FoamRipper machine back into my work area. This machine currently runs Marlin firmware on an ArduinoMega/RAMPS board stack… and runs headless, using an LCD screen and SD card for control and input. The bed is a 32"-wide interior door which I’ve cut down from 6’8" to 4’8" to make handling a bit easier. I installed the gantry and tried not to bang things around too much while moving it… thankfully, it powered up first time and seemed to be pretty much in the same condition I left it, from before Christmas last year.

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This is the candidate machine I’ve selected for permanent installation of LinuxCNC and the inexpensive LinuxCNC interface board set I’ve been developing, subject of another thread. This machine is somewhat similar in form (moving gantry) and function (foam-cutting) to the old BuildYourCNC-inspired wooden CNC machine, running LinuxCNC/EMC2, that I used before there was ever a MPCNC to discover and start playing with. Ever a fan of Ryan and his brilliant machines, this project is, for me, simply a fun and interesting way to come full-circle and duplicate the form and function of that old machine – including using LinuxCNC – using MPCNC/LowRider/FoamRipper construction ideas.

The 3-sheet stack of DTFB in the middle is the vacuum pad I was testing when I put the machine away in anticipation of family visits during Christmas. It needs further testing… primarily to reduce noise.

This past weekend, my internet connection was broken for about 30 hours? No forums and no streaming movies/TV… I finally decided that I could do something about tidying up my parallel port interface board set… the rubber bands are simply not going to cut it

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Without internet, however, my favorite online CAD tools are unavailable. But I’ve got OpenSCAD installed on my Mint box… and, for something as simple as a mounting plate, it shouldn’t take too long. So I fired it up and began to play… and soon was able to print a test plate

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After a few adjustments to the height of the standoffs, I printed a second plate

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Much better. A dab of hot glue on top of the standoffs and it should be good enough to hold the boards in place. The plan is to hang the board set on the gantry end plate… where the Mega/RAMPS used to hang

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I am really impressed with the design of these little CNC shield boards. All the pins for external connections are neatly grouped together and the hookup of that 4th “A” device is very versatile. With just a couple of jumpers, the “A” device can be used as a clone of the X, Y, or Z axis… or used for a 4th axis.

For FoamRipper, I’ve got 2 motors driving the gantry along the length of the work surface… and the other two are single motors. So I intend to clone A to Y (as marked on the shield), and then hook up the X step and dir signals from the breakout board to this axis so I have two motor connections. Then Y step and dir from breakout board to X (as marked on shield) and, finally, Z to Z; i…e. I’m swapping X and Y (as marked on the shield) to simplify the wiring for the two-motor X axis. I’m also thinking I may want to use 1:16 microstepping rather than 1:32. We’ll see…

Later.

– David

dkj4linux · March 11, 2019, 1:03pm

Alright! Finished putting the parallel interface board set together and installed it onto the gantry end-plate, where previously the Mega/RAMPS had been.

I am really impressed with the design of these little Uno CNC shields. All the pins for external connections are neatly grouped together and the hookup of that 4th “A” device is very versatile. With just a couple of jumpers, the “A” device can be used as a clone of the X, Y, or Z axis… or used for a 4th axis.

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For FoamRipper, I’ve got 2 motors driving the gantry along the length of the work surface… and the other two are single motors. So I cloned A to Y (as marked on the shield)… and then hooked up the X step and dir signals from the breakout board to this axis, where I now have two motor connections. Then Y step and dir from breakout board went to X (as marked on shield) and, finally, Z to Z; i…e. I’ve swapped X and Y (as marked on the shield) to simplify the wiring for the two-motor X axis. The two jumpers just above the blue screw connections cloned the A device to Y (not populated yet)… and these two right-most devices are my new X axis. I’ve also setup DRV8825 1:16 micro-stepping rather than 1:32… just for grins. A dab of hot-glue holds the boards (hopefully securely!) to the standoffs on the mounting plate.

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Installed interface on the gantry end-plate. BTW the USB cable is simply supplying +5v logic power to the interface… no data.

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Yeah, it’s bulky but it can be broken down pretty easily/quickly… and sized to cut full-size foam sheets of interest to most RC’ers

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and first moves! Air-milling the EMC2 logo from precious tests…

I’m quite pleased with my morning’s work. Time for a nap…

– David

dkj4linux · March 11, 2019, 9:23pm

Getting closer…

Set up a FoamRipper configuration. Loaded a SVG file I’d created using the Blackstripes extensions into Estlcam and created a gcocde (.ngc) file. Not too bad for a ballpoint pen… though there are a couple of small ink blobs I wish weren’t there. Took a little less than an hour to print.

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– David

barry99705 · March 12, 2019, 4:53am

That’s pretty cool!

dkj4linux · March 13, 2019, 12:44pm

Ok… time to move on. I know folks are getting tired of me showing these machines in operation… doing everything but needle-cutting foam. But there is a method to my madness…

Several have mentioned that it would really be of great utility and interest if we could do artwork/linework/decoration on a plane’s parts prior to cutting it out using the needle-cutter. Shouldn’t be a problem as far as the machine is concerned… but finding appropriate software to accomplish it might be.

Here, I’ve used Inkscape to create an outlined hatched-circle pattern, shown below. I’ve used the Eggbot extension to cross-hatch the inner circle – representing an arbitrary “filled” area – and moved it to it’s own layer… this is the “artwork” to be done with pen or marker. The outer circle is the “outline” to be done with the needle cutter… and is moved to it’s own layer. Not sure at this point how valuable this “layering” will be but it seems like a good idea to me.

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So I saved the SVG (contains both layers) and then imported it into Estlcam (which I think ignores the layers). There I selected all the artwork to be “engraved” with the “pen” tool and created a gcode file for “artwork”. I then deleted all the “artwork” toolpaths… and selected the outer circle to be engraved with the “needle” tool. After previewing to insure just the outer circle would be engraved, I then saved the gcode file for “outline”.

My machine currently mounts both a needle-cutter and a pen-holder… the offsets between the two will be determined later. But for now – for quiet/quick/compact and less wasteful reasons – I’m using paper and pen (rather than foam and needle cutter) for both the artwork and outline runs. The procedure should not change.

So, I placed a clean sheet of paper/foam on the work-surface and moved the pen/marker into a starting position over the material… setting this location as X and Y “home”. I then lowered Z to find the top of the material and set this as Z “home”. IMPORTANT: I then manually pressed on the pen (this could be automated I suppose) to insure a small mark was made on the material surface… this is for registration purposes for the next operation. I then ran the gcode for “artwork”.

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Upon completion of the “artwork” step(s), I ran the pen out over to a random area and UN-homed the machine… losing all origin information. I then jogged the pen back into the vicinity of the registration mark and then “sneaked up” on it, first in X and Y, and finally Z. Setting the “jog rate” slider on the Axis interface to a low value and using the keyboard made this quite easy to align the pen tip (needle tip) with the registration mark.

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and, finally, run the “outline”/cutting operation

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Carefully done, this should yield “good enough” registration between the “artwork” and “outline” operations… for all but the most “picky” of us

So, that’s the plan… as I see it now. I think identifying software and generating the artwork… with dark lines and filled areas suitable for CNC… may well be the “hard” part.

Thoughts? Ideas?

– David

jeffeb3 · March 14, 2019, 12:14pm

That’s a good idea.

Method a) I haven’t ever tried to do multiple tools in Marlin, but I think you can set specific tool offsets, so if your were at 0,0 and then selected tool #2, and moved to 0,0 the new tool would be over the work’s 0,0 location. This would be great in the long run, because you could store the information in the firmware, where it belongs, and only change it if you added more tools or whatever, and your old gcode files would still work fine. The trouble, of course, is the learning curve. I know offsets confuse people (they confuse me, at least).

Method b) If I were doing this (and I was considering a similar problem for the low rider laser vs milling bit), I would probably calibrate the offset, write it down and do something like this:

G1 X0 Y0 Z0 ; Move to a happy place
G1 X10 Y20 Z0.5 ; Move by the calibrated amount between the two tools
G92 X0 Y0 Z0; Tell the machine that this is it’s new home

I would do that because I understand that gcode, and I would be able to look out for trouble like burying the bit before each command.

Method c) I like your solution, though. It definitely is easier and easier to understand. I would probably just switch it around so you aren’t losing your home position, you are just putting the new tool on the registration mark and doing a new G92.

A long time ago (in the days when a home CNC was a pipe dream), I wanted to make a settlers of catan board from laser cut wooden boards. I’ve since not played catan enough to justify it, but I would still like to do it. The pieces can’t be cut out with my wimpy laser though, so I would need to etch with the laser and cut the parts using the dewalt. It’s a similar job, I think.

I also think there’s quite a bit to be gained from “just” getting something drawn on the plane. Even if it doesn’t align exactly, you’ve got a tool that is much more versatile and can apply some very neat designs.

The hard part is definitely finding some art, applying it to the design of the plane cut file, and then forcing it through CAM. It would almost be more useful to have some neat art that you could apply to the whole sheet, and then cut out wherever the wings and parts end up. Say, there’s a great sand tool I know of that can make attractive patterns that scale well…

dkj4linux · April 23, 2019, 7:09am

For completeness sake… when I last left off with FoamRipper, I was starting to wander off into an area I have less interest in, and practically no use for, given that I’m no longer really cutting, building, decorating, and flying planes. So, I weenied out again, and chose to concentrate on the machine itself… specifically, the FoamRipper’s carriage, Z-axis, and needle-cutter.

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If interested, the development of this carriage and cutter is detailed in two RC forum threads… refer to either of these for more information regarding the carriage and needle cutter construction and design.

https://forum.flitetest.com/index.php?threads/cutting-foam-sheets-with-a-needle.24251/page-122#post-465429

https://www.rcgroups.com/forums/showthread.php?2566143-Mostly-Printed-CNC-and-cutting-foam/page12#post41499651

I suppose to make this particular activity more appropriate for this site, I can share video and photos of the obligatory MPCNC crown… turn down the sound!

This is DTFB… the Adams papered-foamboard available at most dollar-stores. The paper is what causes the most grief when cutting it… the fuzziness on the cut edges is the paper but the foam is cut clean. Unpapered foams cut very cleanly. Here, the crown stayed on the spoilboard when the waste was lifted…

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Gently working the piece loose… everything loosened, with paper intact…

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Top and bottom sides…

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A more “normal” job for the FoamRipper and needle cutter is cutting plane parts…

The carriage, Z-axis, and needle cutter are now up on Thingiverse

https://www.thingiverse.com/thing:3582124

So I think this brings FoamRipper to a reasonably complete state and I’ll let it be. Thanks to all who’ve shown interest and suffered through!

– David

vicious1 · April 23, 2019, 8:53am

That is amazing that it holds all that detail in the crown and you can just slide the pieces apart. Slick!

dkj4linux · June 18, 2019, 1:49pm

A bit of digression, some exploration, a dose of boredom, 3dprinter sitting idle, parts on hand, a whim of fancy, and a bit of folly… it’s PLAYTIME! Can’t nap all the time

Poor FoamRipper. Built originally with Marlin/Mega/RAMPS, I recently took a nostalgic trip back in time to convert it over to LinuxCNC, the control software I started with, way back in my initial forays into CNC. I had used it, along with SketchUp and the Phlatboyz CAM extensions, to create gcode for all the little bluecore fan-fold foam aircraft my late flying/fishing buddy and I flew in my pasture… as well as all the parts for a second CNC machine for him. I really do like LinuxCNC and thoroughly enjoyed developing the inexpensive LinuxCNC interface documented in this thread… but, by today’s standards (Marlin/Grbl), it is a bit big and clunky. And since there seems little interest, beyond my own, and my curiosity is now satisfied, it’s time to move on to something new…

I’ve built more than a dozen CNC machines over the past several years and virtually all of them started with Marlin/Mega/RAMPS. Since I had a number of the little board sets that I knew worked, I kept using them. One of the machines still in use, an MPCNC laser engraver, sports a miniRambo board now… having been used to help debug the laser raster-engraving issue in newer versions of Marlin.

Somewhere along the way, however, I picked up a couple of MKS Gen L v1.0 controllers. I don’t remember exactly why… other than they were supposedly 100% compatible with the Mega/RAMPS combo I’d been using and was so familiar with.

The digression and exploration… I reverted to the Marlin/Mega/RAMPS scheme from before. However, I used the MKS Gen L v1.0 board this time. I flashed it with the Marlin/RAMPS firmware from this site and applied the RAMPS “pin44 remap” mod (isolated white wire) and set it up for the full-graphics LCD display.

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The isolated white and gray wires are the RAMPS “remapped Fan1 to pin 44” mod for TTL laser modulation, using M107 and M106 Sxxx gcodes for control…

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Boredom and fancy… I had thought I might play with putting a laser on the FoamRipper. Pretty useless, really – diode lasers won’t cut foam-board – but I thought it could be fun to play with as an engraver. So, my compact carriage and Z-lift got a new appendage and became a bit the monstrosity… sporting one of the Eleksmaker 2.5 watt laser modules I had on hand. Pen/marker, needle-cutter, and now laser… all mounted on the same carriage together.

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And, in action…

So, it works… but is of dubious value. But it keeps me off the streets and gives me something to do between naps

– David

dkj4linux · June 24, 2019, 8:23pm

Adventures in air-assist…

Still a fan of “pawpawpaw85”'s air-assist shroud I’ve used several times, I’ve discovered one I think I like a bit more… “danwar”'s “Laser Air Assist Shroud” (https://www.thingiverse.com/thing:2626593). I’ve replaced the radial fan, however, with a small printed adapter that allows connection of some vinyl tubing (3/8" ID x 1/2" OD) from the big box store. At the other end, I’ve connected a fairly nice, relatively quiet, air pump… powered by an inexpensive router speed control, for adjusting the flow of air from nozzle.

A crude test over the range of the speed control, showing the air flow from MIN to MAX…

Here’s the air pump, router speed control, and vinyl tubing connected through another printed adapter…

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Shroud with printed adapter and vinyl tubing…

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Mounted on the FoamRipper’s laser housing…

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Top-view…

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and “shades of gray” test run.

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Later.

– David

vicious1 · June 24, 2019, 8:53pm

What is that pump from, is it a mini vacuum in reverse? That seems like a great idea, some can’t handle any sort of back pressure but that seems to be doing great.

dkj4linux · June 24, 2019, 9:21pm

That’s actually an OzarkTrail air-mattress pump my kids left behind when they moved. I found a couple of Coleman air pumps as well… but they are considerably louder.

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barry99705 · June 25, 2019, 4:50am

Neat! I have a couple of those inflator thingies around here somewhere.

jeffeb3 · June 25, 2019, 5:21am

I have the loud ones. The NiCd version died, so I soldered a lipo connector to it. It’s still loud, but much lighter (and dangerous!).

dkj4linux · July 10, 2019, 8:48am

Further adventures with a 2.5 watt Eleksmaker laser, cutting/engraving, and air-assist…

After noting a stronger, higher-pressure blast with the Loc-line flexible coolant hose and nozzle, I decided to try printing a nozzle extender for the stock nozzle for Danowar’s most-excellent air-assist shroud…

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All these pieces (no, he doesn’t need ALL of them but I needed a test subject…) were cut and engraved with the same 2.5 watt laser… starting with the cereal-box cardboard (chipboard?) on the far left and – going clock-wise – 3mm birch plywood, stencil board, and the last two, 5mm luan plywood from the big-box store…

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For cleanest, crispest detail, I’ve found that the nozzle-extender cone is best used for cutting and the stock nozzle for engraving… thankfully it’s simple to put on and take off. Engraving – with the extender – I got a “smudged”/“smokey”/“charred” look… without the extender, I got the lighter, crisper, cleaner engraving. Below, the same file, same material, and exact same laser settings… but with the extender (left) and without (right)…

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These two 5mm luan plywood pieces were engraved with the same file and laser settings… the darker engraving (background) was with the extender cone, the lighter one without…

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More to come. This is fun stuff…

– David

dkj4linux · July 10, 2019, 9:02am

With the extender cone, and MAX air-blast from the OzarkTrail air pump, I was able to cut materials I haven’t been able to cut previously… all the way up to 5mm luan construction plywood/paneling from the big-box store…

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This is not fast, mind you… but it is possible, with patience. I’m not sure exactly how many passes it actually took to cut completely through on the outline cut… but I was sure it was cut through after 11 passes at full-power, full-air, and 100 mm/min feed rate. It could have been 8, 9, 10… or 11. I use a rather crude way to not lose count… placing another item in the string when starting each 6 minute outline run…

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With patience – and ABSOLUTE BEST FOCUS and STRONG AIR-ASSIST – it is possible to work your way through material a lot of folks say is not possible to cut with such a low-power laser. I really think it is the smaller spot size. I was a bit surprised, several years ago, to find that my first 3.5 watt lasers didn’t seem any more “powerful” than the 2 and 2.7 watt laser I’d played with previously… so I’m pretty sure its a “power density” thing; i.e. 2.5 watts concentrated in a “unit area” is more “powerful” than 3.5 watts spread over 4X that “unit area”.

I’m going to stop here for now. Having a “blast”… with air-assist

– David