ROBOTICSPERSONAL

TEA. EARL GREY. HOT.Jean Luc Picard of Star Trek fame

had high tech replication gadgets athis disposal. In his Utopian sci-fifuture, these devices would be socommon that they were used forsuch mundane tasks as making a cupof tea in the captain’s quarters.Although we have a long way to gobefore we can expect any item weask for to pop into existence from awall-mounted gadget, some intrepidfolks are diligently working in thatdirection, starting with automatingthe creation of parts.

When building things both robotic and mundane, I’ve foundmyself sanding, cutting, shaping,bending, and otherwise changing thephysical shape of some item used ina project. In many cases, creatingexact duplicates of a part is critical tomaking something that balances orrequires matching or aligned holes.Creating these things by hand can berather time-consuming. It sure wouldbe nice if I could just draw what Ineeded and then have a device thatwould cut the part for me. Thoughnot exactly up to the “replicator” on Star Trek, if automatic part-makingsounds interesting to you, then aCNC machine is a pretty good place to start.

I SEE, CNC!CNC or Computer Numeric

Control is an acronym that refers to atool that can cut or shape by usingcomputer generated instructions (seethe sidebar for a bit of history). MostCNC machines have a number ofaxes and a tool of some sort that canbe guided by a computer to very precisely remove material. Originallycreated in the 1940s for the automa-tion of large-scale manufacturing(Figure 2), CNC has become morecapable over the years and has madeits way down to small desk top fabrication systems. Though somesmall-project CNC systems are available to the hobbyist, most are inthe multi-thousand dollar range so theyhaven’t seen muchwidespread adoption inthe humble homebrewmarket. Until someonecan get the price downto sub-thousand dollarlevels, we probablyaren’t going to see

many of these tools on a typicalhobby workbench.

BRINGING DOWN THEPRICE

I was having lunch with long-timeRobot Group member and goodfriend Paul Atkinson at Pok-e-Jo’sBBQ restaurant here in Austin, TXwhere we were munching BBQ andtalking tech while the electric traincircled the dining room (see TheTrainSaver, Nuts & Volts, July ‘06).Paul mentioned that he had recentlyread about a new CNC machinefrom PROBOTIX that seemed to havefinally managed to break the $1,000

UNDERSTANDING, DESIGNING & CONSTRUCTING ROBOTS & ROBOTIC SYSTEMS

■ FIGURE 2. A CNCturning center in the

FAME Lab in theLeonhard Building atPenn State. (c) 2005Nathaniel C. Sheetz.

December 2008 69

IN THIS MONTH’S ISSUE, WE CONSTRUCTTHE PROBOTIX FireBall V90 CNC router from akit and then put it through its paces.

THE PROBOTIX FIREBALLV90 CNC ROUTER

■ BY VERN GRANER■ FIGURE 1.The PROBOTIXFireBall V90CNC router.

hobbyist CNC router. A bit of investigation showed PROBOTIXoffered the FireBall V90 CNC routerfor $599 plus another $309 for anentry-level motor kit that included the stepper motors, the power supply, and the motor controllers.Add in shipping, and you can have acomplete CNC router kit on yourdoorstep for less than a kilo-buck! Allyou have to provide is the homecomputer (with a parallel port) to run the software and a Dremel®moto-tool to use for cutting.

I sent an initial inquiry to JohnHansford over at FireBall CNC to getsome information on the availabilityof the product and to see if theywould be interested in having theirCNC router covered in Nuts & Volts.John seemed excited about theprospect and put me in touch withLen Shelton over at PROBOTIX.Before I knew it, Len had my orderfinalized and just a few days later I had one big (heavy) box on mydoorstep. Looks like it was time forme to dip a toe into the waters of CNC fabrication, but first I had

to build the machine itself.

IT’S HERE!Amazingly, I received the Fireball

CNC in a single box (Figure 3). Itweighed in at 56 pounds and wasextremely well packed (seemed likethe person who did the packing mustbe pretty good at Tetris!). Overall, thebox measured 27” by 16.5” by 8.5”leaving me wondering how theycould fit everything in there. Ichecked the packing list/invoice andit appeared that everything was onthe list.

Inside I found two smaller boxesand lots of things wrapped up inbrown paper (Figure 4). It still didn’tlook like there were enough piecesto build a machine but, by the time Ifinished unwrapping everything, theparts were all accounted for. When Isaid everything was well packed, Iwasn’t kidding!

I found that the large side tubescontained the smaller side tubeswhich contained the lead screws andmotor couplers and the threadedframe tension rods (Figure 5). Notonly was this a nice use of space, butit was also a very effective way to

protect the delicate parts while in transit.

After carefully emptying thelarge box and laying out all the

components on the kitchen table, Iwent to both the Fireball CNC andPROBOTIX websites to look forinstructions or pictures to help mewith the assembly. I identified all ofthe major parts and located a coupleof tools to help in the process. Theprimary tools were a 7/16 inch nutdriver, a Phillips screwdriver, and aset of Allen wrenches (hex keys).

After identifying the major parts,I cleaned the protective wax from the precision ground and hardenedThomson shaft with some acetone. Ithen installed the smallest set of rodstransverse to the Z axis. I installed theZ axis and rods between the gantryuprights and added the gantry backand base. Next, I added the X drivenut to the bottom of the gantry base.This was starting to look like a CNCmachine already (Figure 6).

The next step requires a coupleof magazines to hold the frame endplate off the work surface (Figure 7).The frame is assembled vertically to

70 December 2008

■ FIGURE 3. The 56 pound shippingbox from PROBOTIX.

■ FIGURE 5. Painted support tubescontaining Acme lead screws (withbrass couplers) and threaded tensionrods (top).

■ FIGURE 6. Gantry with Xaxis travelling nut attached.

■ FIGURE 4. Nested packages insidethe shipping box.

December 2008 71

make it easier to install the threadedrods which tension the frame endsand hold the base together. The magazines provide clearance for thenuts on the end of the threaded rods.The holes that these threaded rodsgo into are surrounded by a slightlycone shaped recess which helps toguide the rods into and through theappropriate holes.

The precision-ground shafts areput into the gray bushings and theend tubes are put in place. The bushing plates that later connect tothe gantry base are added next.(Make sure you install these the rightway around as it is tedious to turnthem around later.) Finally, the otherframe end plate is added and held inplace with washers and nuts addedloosely (Figure 8).

At this point, the frame can beput flat on the work surface and thegantry is loosely bolted to the gantrybushing plates. Alignment of the unittakes place at this point (before thelead screws are added). By movingthe gantry and Z axis assembly backand forth with a finger while carefullysnugging up the existing bolts, youcan tell if things are in alignment byhow easily things slide on theThomson shafts. Once you have thealignment feeling right, you can tighten the bolts about a half turnpast finger tight.

Now that we have the tabledone, it’s time to add the lead screwsthat the motors will use to controlthe motions. There are several washers and locking collars whichwere in small, well labeled bags

(Figure 9). It is important to put theseparts on in the correct order. (Note:The Z axis assembly already has itsrods and lead screw installed, so weare only dealing with the X and Y axishere.) Once the lead screws areinstalled, I again turned them byhand to make sure there was nobinding anywhere across the range ofmotion for both the X and Y axes.

AND NOW, FOR SOMEELECTRONICS!

At this point, the complete $599FireBall V90 CNCrouter is assembled. It’snow time to move onto the electronics pack-age. In the standardmotor package, the

blue motor goes on the Z axis andthe yellow motors go on the X and Yaxes. Someone was thinking aheadwhen they thought of color-codingthe motors! A quick tip: Beforemounting the motors, you may wantto consider grinding a flat on theshafts. This will allow the coupler set-screws to make a better seat.

P E R S O N A L R O B O T I C S

■ FIGURE 7. Magazines used toraise rear support off work surface

to allow clearance for hex nuts.Keeps unit stable for several

assembly steps.

■ FIGURE 8. Front support attachedto tension rods (inside silver tubes)

via acorn nuts and washers.

■ FIGURE 9. Starting at top centerand going clockwise: table supports,tool holder, Z axis assembly, hookup

wire, fuses, fuse holders, power cord,lead screw bearings and clamps, and

assorted bags of hardware.

■ FIGURE 10. Motor hardware— metal washers go between

motor and nylon standoffs.■ FIGURE 11. Z axis motor in place —ready to tighten screws.

The motors are mounted usingnylon stand-offs (Figure 10), and bolted to the top of the Z assembly(Figure 11) and to the gantry orframe side members. I followed theillustrations in the instruction manualand mounted the motors in the standard locations. (Some have asked

if the motor can be mounted on theback of the frame and John Hansfordhas verified that it is possible to doso, if you prefer.) While working withthe machine, I realized that even withthe motor wires disconnected, themotors can be hard to turn. I addedsome knobs (RadioShack part num-ber 274-407) to the back shaft ofeach motor so I could easily turn theshafts for manual zeroing and to savemy fingers! Wiring the motors was surprisingly straight forward. The onlytrick was realizing that several of thewires go to the positive motor supplyand can be connected together toone wire in the cable (Figure 12).Make sure you leave enough cablelength appropriate for each axis sincethey all have different travel

distances. I mounted the motordrivers, relay board, and breakoutboard on a piece of wood that waslarge enough to also hold thepower supply (Figure 13).

HARD PART’S DONE,TIME FOR SOMESOFTWARE!

I had help from another

good friend, Robot Group memberand Linux expert James Delaney ingetting the Ubuntu Linux distribution,EMC2 and Inkscape software up andrunning on my desktop PC (Figure14). After playing with the softwarefor a bit, I posted a question to theFireBall forum asking questions aboutInkscape (a GNU/open-source designsoftware I was trying). I detailed howI had encountered some difficultywith the apparent lack of an integratedsoftware solution for both the designand tool-path planning end of things. I had a look around at thecommercial offerings and, after reading some suggestions on theforum, downloaded a trial version ofMach3, an advanced CNC controlapplication (Figure 15).

Meanwhile, John Hansfordanswered my posting (he’s quiteactive in the forum) saying heencountered similar issues and suggested a software package fromVectric called Vcarve Pro. I down-loaded the trial version of the software that allows you to try outthe design aspect and then cut theexample files on your CNC (Figure16). John spoke with Tony McKenzieat Vectric and arranged for a fullcopy of VCarve Pro to be sent out tohelp speed our preparations forMaker Faire (thanks Tony and

Vectric!). I used VCarve Pro toimport several bit mappedimages and perform the toolpath planning for our MakerFaire give-aways (Figure 17).

I think it’s pretty amazingthat there are so many choices for for small-scaleCNC software including bothGNU/open-source, as well ascommercial applications.

My final approach was a

72 December 2008

■ FIGURE 12. Stepper leads attachedto cable with solder and heat shrink.I did this slightly different than PROBOTIX since I used orange andshield as V+ conductors (they onlyuse orange in the gray cable).

■ FIGURE 13. 24V Power supply,relay board, three motor drivers, and breakout board mounted withfuse holders.

■ FIGURE 14. Starting up EMC2 onUbuntu Linux.

■ FIGURE 15. Mach3 Software up andrunning on Windows.

■ FIGURE 16. VCarve Pro withexample artwork.

hybrid of all the different packages. Forexample, my firstattempt at running themachine involved manual jogging andrunning the motor tuning setup withinEMC2. I then mountedthe standard tool holder which isdesigned to work witha Dremel model 300 rotary tool andthen placed a felt-tip marker in it totest out some drawings. I drew several patterns using the varioustools and had success drawing onpaper taped to the work surface(Figure 18). By now, I was feelingmore confident that I knew what Iwas doing so it looked like it wasfinally time to cut something.

CUT IT OUT, ALREADY!I installed my trusty old Dremel

model 385 Multipro and found itwasn’t quite a snug fit. I shimmed itwith some thin card stock and wasable to use it for cutting in foam. Infact, I even used one of the fewpieces of packing foam from the boxto carve the sample torus file inEMC2 (Figure 19). Sure was nice ofPROBOTIX to provide some testmaterial!) Carving foam was fun for awhile, but then it was time to find away to make a sacrificial work surfaceand come up with a clamping systemso we could cut something a bit

more substantial than packing foam.

MAKE: IT HAPPEN!About this time, Maker Faire

Austin was approaching and TheRobot Group was preparing a list ofprojects for the show. As we had anice new CNC router, we decided toshowcase it at the Austin event. Wedecided the best way to demonstratethe power of the router was to makesmall give-aways of some type. Aftertoying with cutting shapes out ofrecycled vinyl LPs (the finished vinylpieces turned out to be too fragile),we decided on recycled CDs as ourmedia. This required a clamp that

could hold down the CD so it couldbe held tight while being cut. Again,another Robot Group member cameto the rescue. Rick Abbott machinedan aluminum shoulder washer thatperfectly fit the hole in the center ofthe CD (Figure 20). That solved my

HISTORICAL OVERVIEWCNC was preceded by NC (Numerically Controlled) machines, which were

hard wired and their operating parameters could not be changed. NC wasdeveloped in the late 1940s and early 1950s by John T. Parsons in collaborationwith the MIT Servomechanisms Laboratory. The first CNC systems used NCstyle hardware, and the computer was used for the tool compensation calculations and sometimes for editing.

Punched tape continued to be used as a medium for transferring G-codesinto the controller for many decades after 1950, until it was eventually superseded by RS-232 cables, then floppy disks, and now is commonly tieddirectly into plant networks. The files containing the G-codes to be interpretedby the controller are usually saved under the .NC extension. Most shops havetheir own saving format that matches their ISO certification requirements.

The introduction of CNC machines radically changed the manufacturingindustry. Curves are as easy to cut as straight lines, complex 3-D structures arerelatively easy to produce, and the number of machining steps that requirehuman action have been dramatically reduced.

With the increased automation of manufacturing processes with CNCmachining, considerable improvements in consistency and quality have been achieved with no strain on the operator. CNC automation reduced the frequency of errors and provided CNC operators with time to perform additional tasks. CNC automation also allows for more flexibility in the wayparts are held in the manufacturing process and the time required to changethe machine to produce different components.

**From Wikipedia

December 2008 73

■ FIGURE 17. First layoutfor CNC cutting keychains

for Maker Faire.

■ FIGURE 18.About 1.5”

square patternof lab glassware.

■ FIGURE 19. First cut of Torus (roughlower edge due to mismatch of cutter

and Z depth).

■ FIGURE 20. Custom-machinedaluminum shoulder washer holds a

CD steady as the Dremel routes agear pattern.

P E R S O N A L R O B O T I C S

clamping issue, but I had some problems cutting plastic without melting it and soon found out thatspecial cutters and lower cuttingspeeds are required. Fortunately, Lenover at PROBOTIX was willing to dosome research on cutting bits andeven offered to fly down for theshow to provide on-site technical(and moral) support!

As the router would be operatedin a public area, I thought it wouldbe a good idea to create a displaycabinet to keep noise and debrisinside and curious fingers out. I enlisted Wolf Dilworth (yep, anotherRobot Group member) and BruceTabor to help craft a nice wood andPlexiglas cabinet to showcase theCNC machine. The display case wastransparent on three sides and incorporated an internal lighting system making it easy to see therouter strut its stuff (Figure 21).

The day of the show arrived andPaul Atkinson stepped up to the plateto operate the CNC router with LenShelton from PROBOTIX at his sidefor two full days of exhausting, exhilarating Maker Faire fun (Figure22). Len spent a considerableamount of time tuning the systemand sharing his experience with us.He even solved the “cutting bit melting the CD” problem we originallyencountered. Len had contacted the

owner of Precise Bits to discuss the results we weregetting while cutting CDs.They told us we weren’tusing an optimal bit andthey overnighted the rightones to Len. Turns out a“spiral up-cut bit” was just

the thing for cutting CDs cleanly(thanks Precise Bits!).

After spending some time cuttingCDs at the show (Figure 23), wenoticed my older model 385 exhibited some run-out (off centerrotation) it had developed over theyears. The very generous folks in theDremel booth at the show offered usa free Dremel 300 to use in therouter! The new Dremel 300 workedthe whole day with hardly any noticeable run-out.

On the second day, after gettingcomfortable with the V90 using theDremels, we decided to upgrade to aPorter-Cable trim router that Len hadbrought with him so he could showthe versatility of the V90 with a morepowerful tool (Figure 24). Len andJohn both recommend that you get familiar with the V90 and itscapabilities using a Dremel toolbefore you make this upgrade (andfor good reason). Using the Dremel,you can learn a lot while not risking

74 December 2008

■ FIGURE 21. Containment/protectiondisplay box created for Maker Faire.

■ FIGURE 22. Paul Atkinson(left) and Len Shelton (right)pose with the FireBall V90 atMaker Faire Austin.

■ FIGURE 23.Recycled CDROMscut into Keychains.

■ FIGURE 24. Many of the finishedpieces created and distributed to

folks at Maker Faire Austin.I (TRULY) GET BY WITH A LITTLE HELP FROM MYFRIENDS ...

Some of you may recall fromprevious articles how I describedThe Robot Group here in Austin asmy “pallet of talent.” The group is atremendous resource and I havefound I can always count on themto step up to the plate in a time of need.

Just after I started on this article, I packed up my house andmoved out of Austin to DrippingSprings, TX in preparation for building a new house. The movewas more disruptive than I could

ever have imagined. Paul Atkinson,Vice President of the group and agood friend, came to my rescue bytaking over the CNC mill and buildas the move left me with no shop ofany kind to work in nor any time inwhich to work!

In addition to assembling themachine, he took a bunch of greatphotos (all the assembly photoswere courtesy of Paul) and evenwrote up extensive notes whichaccount for the bulk of the construc-tion detail in this article. I owe Paula debt of gratitude and probably aBBQ dinner (or two!) out here in the“country!” Thanks Paul! Couldn’thave done it without you buddy!

the damage an “oops” with amore powerful router can cause.In fact, for those of you doingonly small or fine work, theDremel may be all you will need.

The V90 worked perfectly for the entirety of Maker Faire, running continuously over thetwo days and even winning anEditors Choice ribbon for our display (Figure 25)! In reality, wehad more down time with clamping issues and/or workingon software designs than anythingelse. Bottom line is the V90 is a solidpiece of gears that can be easilyassembled in an hour or two. Withthe well-matched electronics package, it makes a solid CNCmachine that you can use and enjoyfor hobby and light commercial use.It stood up to a demanding showschedule without skipping a beat.

It can cut foam, MDF, wood,plastic, fiberglass, light carbon fiber,printed circuit boards, and solid surface (synthetic counter-top) material and we look forward to trying it out on ALL those materials!Though the FireBall’s creator hasreservations about doing so, somebrave souls have even tried workingmetals with the V90, performing lightcuts in aluminum and brass with verygood results (check the Resources

section for the V90 forum whereusers discuss their experiences). It allcomes down to having a solidmachine (PROBOTIX and FireBallmake that part easy) and thepatience to learn.

The PROBOTIX FireBall V90CNC will be a centerpiece in myworkspace for the foreseeable futureand, based on the results so far, Ithink you can expect to see anotherentire article devoted to using theV90 to create parts a bit more usefulfor hobby robots than key chains(Figure 26)!

As always, ifyou have anyquestions,please feel freeto email me atvern@txis.com.NV

P E R S O N A L R O B O T I C S

December 2008 75

■ FIGURE 25. Paul Atkinson shows off theEditors Choice blue ribbon won for the

FireBall CNC display at the Faire.

■ FIGURE 26.CD-ROM Gearsand Key chains.

RESOURCES■ PROBOTIX —

wwwwww..pprroobboottiixx..ccoomm

■ FireBall CNC —wwwwww..ffiirreebbaallllccnncc..ccoomm

■ PROBOTIX FireBall V90CNC at Maker FaireAustin 2008 —hhttttpp::////mmaakkeerrffaaiirree..ccoomm//ppuubb//ee//22115511

■ FireBall V90 chat forum— hhttttpp::////ggrroouuppss..yyaahhoooo..ccoomm//ggrroouupp//FFiirreebbaallllccnncc

■ VCarve Pro —wwwwww..VVeeccttrriicc..ccoomm

■ Precise Bits —wwwwww..pprreecciisseebbiittss..ccoomm

■ ArtSoft Mach3 CNCSoftware — wwwwww..mmaacchhssuuppppoorrtt..ccoomm

■ Linux CNC “EnhancedMachine Controller -EMC” — wwwwww..lliinnuuxxccnncc..oorrgg

■ Dremel Tools —wwwwww..ddrreemmeell..ccoomm

■The Robot Group —wwwwww..TThheeRRoobboottGGrroouupp..oorrgg

■ Pok-e-Jo’s BBQ in Austin— wwwwww..ppookkeejjooss..ccoomm

■The Train Saver —wwwwww..nnuuttssvvoollttss..ccoomm//pprreevviieeww..pphhpp??iissssuuee==1111

I’d like to thank Len Shelton andJohn Hansford for making the PROBOTIX FireBall V90 CNC a reality and for making a sub-$1,000commercially available CNC system a reality. Also, special thanks to TonyMcKenzie at Vectric for the VCarve Prowe used at Maker Faire. You guys rock!

I’d also like to thank Paul Atkinson(hardware/photography/electronics),James Delaney (software), Rick Abbott(parts fabrication), Wolf Dilworth andBruce Tabor (display case construction),and Kym Graner (show coordinator) fortheir assistance and support!