CNC Pumpkin Carver A Baccalaureate thesis submitted to the Department of Mechanical and Materials Engineering College of Engineering and Applied Science University of Cincinnati in partial fulfillment of the requirements for the degree of Bachelor of Science in Mechanical Engineering Technology By Adam J Frueh April 2016 Thesis Advisor: Professor Janet Dong, Ph.D.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
CNC Pumpkin Carver
A Baccalaureate thesis submitted to the Department of Mechanical and Materials Engineering
College of Engineering and Applied Science University of Cincinnati
in partial fulfillment of the
requirements for the degree of
Bachelor of Science
in Mechanical Engineering Technology
By
Adam J Frueh
April 2016
Thesis Advisor:
Professor Janet Dong, Ph.D.
CNC Pumpkin Carver Adam J Frueh
ii
TABLE OF CONTENTS
TABLE OF CONTENTS .......................................................................................................... II
FIGURES AND SURVEYS ................................................................................................... III
TABLES .................................................................................................................................. V
ABSTRACT ............................................................................................................................ VI
DESIGN #1, STATIONARY TOOL AND X AND Y AXIS ROTATING OBJECT. ........................................................... 14 DESIGN #2, X AXIS ROTATING OBJECT AND Y AXIS TOOL (ROCKING) ............................................................... 15 DESIGN #3, X AXIS ROTATING OBJECT AND Y AXIS TOOL (LEAD SCREW) ........................................................ 15
A. RESEARCH .............................................................................................................................................. 38 B. SURVEY .................................................................................................................................................. 39 C. QFD ........................................................................................................................................................ 40 D. BILL OF MATERIAL/BUDGET OF MATERIALS ........................................................................................... 41 E. SCHEDULE............................................................................................................................................... 42 F. BUDGET .................................................................................................................................................. 43 G. DATE SHEETS .......................................................................................................................................... 44 H. DRAWINGS .............................................................................................................................................. 46 I. FABRICATED PARTS ................................................................................................................................ 50
Figures and Surveys
1 Older traditional pumpkins
2 Intense carving
3 Professional CNC milling
4 DIY CNC milling machine
5 Carving Kit
6 PunkinBot
7 PunkinBot 2.0
CNC Pumpkin Carver Adam J Frueh
iv
8 Design Concept 1
9 Design Concept 2
10 Design Concept 3
11 Near Final Product
12 Dremel Rendering
13 Compression Housing
14 Compression Housing Connector
15 Z-Axis Moving Assembly
16 Z-Axis Carriage
17 Curved Rail & Carriage
18 Lead Screw connection
19 Y-Axis Assembly and Z-Axis Assembly
20 Platform, Mounting Arms, and Vice
21 Complete X-Axis Platform and Vice
22 BRA and Gear Train
23 The XYZ Axis together, templates highlighted
24 Aluminum Rails
25 Bearing Assembly
26 BRA
27 BRA riding the rail
28 Complete curved Rail
29 Rail individual Sections
30 Slider w/ V groove bearings
31 Slider on Rail
32 Slider on Rail
33 Finished, Z Axis w/ Nose Cone
34 Nose Cone
35 Protruding Milling Bit
36 Milling Bit
37 NEMA 17
38 NEMA 23
39 2.5 amp Driver
40 Breakout Board
41 Electronic Board
42 Main Screen of Mach3
43 Computer setup
44 EasyCAM
45 Finished Wired Board
46 Deflection visualization
47 Deflection Scale
48 Gear Train Sketch
49 Center Distance
50 Spring Mechanism
51 Front view in the works
52 Left Side view in the works
53 Dremel and Clamps
CNC Pumpkin Carver Adam J Frueh
v
54 Complete Housing
55 Z-Axis Carriage
56 Brackets
57 Gluing the Rails
58 Final Lead Screw Platform
59 Top Mounting Arm
60 Bottom Mounting Arm
61 Front wall w/Rail
62 Back wall w/Rail
63 BRA in place
64 Complete Assembly
65 Electronic Panel in place
TABLES
1 Lacerations requiring repair (1)
2 Tendon Laceration (1)
3 Bill of materials and costs
4 Schedule
CNC Pumpkin Carver Adam J Frueh
vi
ABSTRACT
Halloween is a special holiday for a lot of people in America. It’s hosts event for
children and adults alike. Many take to decorating their homes in tombstones, webs, and
lights. But the most widely accepted tradition is pumpkin carving. Millions of pumpkins will
be grown and sold to families with the intention of carving faces or characters on them.
Designs from the simple to the artistic will made and then be displayed for the holidayed.
However hundreds of accidents happen while carving. This is due to improper use of tools
from the kitchen which are not design to carve up the hard uneven flesh of a pumpkin.
Carvers end up slipping causing severe injuries to their hands and fingers that can lead loss of
function temporarily or permanently in the worst of cases. Some products that have been
released are special carving tools slimier to a saw and dale edge tools. While these do remove
a lot of risk they are not entirely safe. In order to reduce the number of accidents, my senior
project is to design and build an Automated Pumpkin carver and remove the human eliminate
entirely. The end result will be a three axis CNC machine that will be able to milling out a
predetermined design. Allowing the user to make high quality designs at no risk and in a
fraction of the time.
No existing patents, although one similar product. PunkinBot is a father-son project
attempting the same thing. They currently have a machine available upon order and has been
able to live up to the description. However I wish to take the idea forward and design a self-
contained unit to prevent any injury as I would design this as a kiosk type machine to be run
in a store for customer use.
This project can be broken down in to a few key factors. The design will need to
support a wide range of pumpkins that would be specific to carving. The spindle will be
mounted and rotated normal to the pumpkin via a curved rail. The z-axis will need to respond
to an uneven surface that a pumpkin would have.
CNC Pumpkin Carver Adam J Frueh
7
Introduction
Halloween is celebrated every year in numerous countries around the world. The holiday
and similar ones like it, are times in the year dedicated to honoring the dead, including saints
or hallows, martyrs, and other member of the respective faith. The tradition is using themes
of humor and ridicule to confront the idea of death. So what do we do for Halloween? Some
people will dress up in costumes (scary or not) and have fun with trick-or-treating. Others
will fixup their house with lights and decorations in the form of webs, tombstones, and other
scary things. But the most popular decoration is Jack-o-Lanterns. A Jack-o-Lantern is a
hollowed-out pumpkin in which holes are cut to represent facial features. This has become a
family tradition for a lot of Americans and others that celebrate Halloween. As digital
imaging technology has improved and simple-to-use media sharing websites have appeared,
the complexity of Halloween jack-o-lanterns being created has been increasing. (2) The past-
time is now deeply rooted into our culture but we have also found it to be a hazardous one.
Improper technic, tools, and supervision for children leads to many cases of hand injuries
reported throughout the holiday. (3)
PUMPKIN CARVING IS BECOMING MORE COMPLEX AND DETAILED
Figure 1 & 2 (4)
Technical Knowledge
CNC MACHINES
If you come from a technical or manufacturing background, then you most likely are
familiar with what a CNC machine is. If not, you should know CNC is an abbreviation for
computer numerical control. A CNC machine, then, is a machine that carves out objects in
CNC Pumpkin Carver Adam J Frueh
8
three dimensions from a solid block of material. CNC machines are commonly used in
industry to produce small parts such as bicycle stems and tools. Low-cost CNC machines are
increasingly used by serious hobbyists, especially woodworkers, to carve creations out of
materials such as wood and aluminum (5). Because it’s become so popular, there’s plenty of
different sources referencing “do-it-yourself” CNC machine builds. Although there is a
fundamental difference between a typical CNC and my pumpkin carving CNC Machine.
We can divide the most basic CNC machines into two categories: turning machines and
milling machines. Turning machines works by spinning a work piece at high speed and a tool
(sharp edge) is brought to the surface which begins to shave off the undesired material from
the work piece, the tool will move forward and
back to the center, or up and down the length of
the work piece until the desired shape is
achieved. Milling machines work much
differently, where the machine that has a
spindle or drill that can cut in various directions
and moves in a standard three axis cartesian
motion (5). Figure 3, Professional CNC milling
http://chopshopcnc.com/services/cnc/
CAM AND G-CODE
These configurations have been around for a long time and wouldn’t need a computer to
create parts. But by adding a computer to the machine controls we can achieve higher level
of quality and repeatability. Today CNC machines produce parts from computer aided design
(CAD) files, which are digital three dimensional parts. To produce the part we just need to
specify to the machine how we what the part to be cut, and that comes from a computer-aided
manufacturing (CAM) file or G-code file, there are also other types but are essentially the
same (5). The CAM file contain all of the steps and operations that the machine will follow
From this point the outside walls of the carridge need to be attached to the Y-Axis. We
will do this in theory by first attaching the carridge to the Curved rails that will rotate the Z-
Axis Assembly around the Templete. This is done by
attaching to the sliders designed for these rails.
Now that the carridge has the ability to rotate around
the templete we need to power it. This is done by the
main installing a vertical lead screw somewhere centered
behide the carriage. It should be far enough away to not
impede the carriage motion and but also made as close as
possible to reduce the length of the lead screw. The
further away this lead screw the longer it must be to
interact with the next feature.
Figure 17, Curved Rail & Carriage
We attach to the lead screw with a vertically
linear moving platform with rotation ends. The ends
have a linear bearing in them and will rotate with the
angle of the carriage. The linear bearings will prevent
the platform from rotating and also provide the
connection and lift for the carridge. Mounting blocks
for the rods will be attached to the carridge.
Figure 18, Lead screw connection
CNC Pumpkin Carver Adam J Frueh
19
Figure 19, Y Axis Assembly and Z-Axis Assembly
CNC Pumpkin Carver Adam J Frueh
20
X-AXIS – PLATFORM AND VICE
This sub-assembly is very different from the Y-Axis and
the Z-Axis as they are not directly connected. They will have
their own template at an opposite plane from the Y-Axis’s
template. The Templates in SolidWorks were center and acted
as one in the complete assembly.
The first things designed are the platform for the
pumpkins. This goes along with the mounting arms and the
attachments that will hold the platforms in place. The
mounting arms need to be long enough to be out of the way of
the biggest pumpkins but strong enough to not deflect under
the weight of the pumpkin or the heavier watermelon. The
platform also acts as the X-axis rotating the pumpkin on the
platform driven by a stepper motor. This stepper motor is best
to be also attached to the lower mounting arm to have a direct
and simple drive train to the platform. Although this will
increase the deflection on the arm.
The platforms will
together work as a vice,
driven by a central gear
that will pull them
together. Compressible
foam will hold the
pumpkin in place. The
central gear is on a gear
train leading towards a
hand crank. The goal of
this train is to easy the
lifting of the weight on the
platform and also move
the crank to the front of
the unit.
Flanking each mounting
arms is a set of BRA and
rails to match. These hold
everything together in the
horizontal directions.
Sandwiched between two
walls.
Figure 20, Platform, mounting
arms and vice
Figure 22, BRA and gear train
Figure 21,
Complete X-Axis
platform and Vice
CNC Pumpkin Carver Adam J Frueh
21
Figure 23, The XYZ Axis Together, Templates highlighted
Now that we have the main components of a CNC we need to build the structure around the
device. Seen in the above picture we have attached the curved rails to panels with a cut out
for the carriage. We start to see the chambers of our CNC machine.
The forward left chamber will be our viewer/working section. Here is where the Pumpkin
will be loaded and the vice will close on the fruit by the user.
The left rear chamber simply leaves room for the gears and timing belt, in a final model this
would be closed off.
The right chamber will have the Y & Z Axis. There is plenty of room to store other things in
the future like the electronics board.
CNC Pumpkin Carver Adam J Frueh
22
LINEAR RAIL ASSEMBLY
Bearing-Rail assembly, I’ve used the term BRA in
other sections of this report to represent this since it’s used
to a hand full of locations. In the test book BYOCNC (5) in
order to get the best movement along all three axes, my
CNC machine is going to use an inexpensive solution that’s
also extremely smooth and accurate. Here’s how it works.
Lengths of aluminum angled rail. These rail consists of two
1/8"- thick walls that meeting at a 90 degree angle (right
angle). Rail width is measured on the outside wall from the
outside edge to the edge where the two walls meet.
This figure shows a few of the pieces of hardware that you’ll
be purchasing—bearing, bolt, and nut. It also shows the three
items assembled. The bearing is the same type of bearing
you’ll find used in skates, 22mm very low-cost
Attaching the BRA can be done in a few ways, the book
suggests drilling pilot holes and screw the rails done, this
works pretty well depending on the heads used. Thou I’ve
Attached mine using bolts, adhesives, zip ties, friction, and
a combination of these for temporary and permanent
placement.
Figure 24, Alum Rails
Figure 25, bearing
assembly
Figure 26, BRA
Figure 27, BRA riding the rail
CNC Pumpkin Carver Adam J Frueh
23
CURVED RAIL ASSEMBLY
This design concept calls for a curved rail to
run the z-axis carriage around the pumpkin. This
enables us to stick to a 3 axis CNC machine. What
is more important is it will keep the drill working
the pumpkin normal to the surface. By that I mean
parallel.
The way to do this is to center the arc of the
rail to where the center of the vice will be. It’s also
important to note that the size of the pumpkin Figure 28, Complete Curved Rail
doesn’t effect this.
Much like the linear rail system these rails
keep the movement of our axis confined. The main
difference is since the rail is curved we need a
better way to fix the movement to the rails. The
solution is instead of simple bearings we will need
to use special v-groove bearings to grip the rail,
ranged properly the bearing can also mesh with a
curved rail seen in figure #.
Figure 29, Rail individual sections
When fabricating this rail it is very important
to make sure the curve is perfect. Making this rail
would be very difficult by hand and very costly if
made in a CNC machine. The solution is to make
a rail in a 3D Printer. The rails you see here are
made in the Universities Rapid Prototyping lab.
They are made out of a plastic filament. To make
thing simple the “Slider” is also made on the
printers and allow attachment of the bearings. It’s
important when making 3D parts that need to fit
tight specs that you add a slight tolerance on your
drawings. These parts then to expand slightly in Figure 30, Slider with v-groove Bearings
the heating process, therefor
add .05” to any critical
measurement. The entire rail
wouldn’t fit in the printer, it
was a simple measure to split
them into thirds and design
pegs to hold them together.
Figure 31 & 32, Slider on rails
CNC Pumpkin Carver Adam J Frueh
24
SPINDLE AND ACCESSORIES
The spindle choice is very important. We need to consider what is necessary for our
needs. Most CNC machines are designed for metal or wood products and require something
powerful but this also means heavy. The heavier the gantry the bigger motors you’ll need and
that means more expensive machinery.
For our needs, carving a fleshy pumpkin, we won’t need anything heavy duty. I’ve chosen to
use the Dremel 200 series because I already owned this tool and would help negate some
costs. The tool is only 2lbs and has a small profile.
Part of this assembly not included in the drawing
is the nose cone. This part extends the physical
connection from the drill to the pumpkin surface that
will compress the springs. The nose can be swapped
out for different lengths. The one shown here will give
us a cutting depth of a quarter inch.
Figure 34, Nose Cone
The milling bit is a special tool. It’s from the RotoZip
sabre cut set. This particular one is meant for drilling
in and milling sideways into wood and plastic sidings.
It will definitely be suited for cutting into pumpkins
and engraving designs.
Figure 35, Protruding milling bit
Figure 33, finished Z-Axis w/nose Figure 36, Milling Bit
CNC Pumpkin Carver Adam J Frueh
25
STEPPER MOTORS AND ELECTRONICS
When picking my stepper motors and the electronics
everything was sourced and suggested by BuildyourCNC.com.
They have very convenient packages and tutorials for the
equipment, not to mention the online forums and quick
customer service has been very helpful.
I decided to go with the NEMA 23 100 Oz-in and the
NEMA 17 62 Oz-in Stepper motors. The X-Axis and the Y-
Axis are going to require some decent torque and the NEMA
100 Oz-in is suggested for my purposes. I decided to do the
NEMA 17 for the Z-Axis for two response, first the reduce Figure 37, NEMA 17
weight and size the second reason is the 100 Oz-in is far more
then what’s necessary.
To drive these motors we will be using the DRV8825
Stepper Motor Controller IC made by Texas Instruments. Each
motor will require its own module to run. This model is a
standalone stepping motor driver that is rated at 2.5 peak amps
per phase. The driver will also accept a range of 8.2 to 45 volts
and can be microstepped up to 1/32 (the step modes are: full,
1/2, 1/4, 1/8, 1/6 and 1/32). The driver chip has all kinds of
built-in protection including protection for heat and over
current. Figure 38, NEMA 23
Connecting the electronics together is the Breakout Board.
I’ve chosen to go with an old fashion parallel port thinking this
would save money thou I didn’t relies my desktop didn’t have a
parallel port. Therefore I went ahead and purchased one for my
computer.
The break out board simply works with the computer Figure 39, 2.5 Amp Driver
program. This board has a relay that controls signals, such
as the router/spindle. There are 11 output pins that can
control various devices such as stepping motor drivers,
coolant, spindle, mist, air, etc. 10 of these pins can be
dedicated to motor axes for a total of 5 axes. 4 Input pins
are provided for limit or home switches.
Lastly to power all of this we purchased a 24 Volt Figure 40, Breakout Board
power supply for the drivers and also a 5 volt adapter for
the breakout board
CNC Pumpkin Carver Adam J Frueh
26
Figure 41, Electronics board
CNC PROGRAM, MACH3
There are three types of software that you’ll be using with your CNC machine. The first
is CAD (computer aided design). This is specialized software that allows you to design two-
and three-dimensional objects for the CNC machine to cut, drill, and perform other actions
on. The second is CAM (computer-aided manufacturing). Easy CAM is the computer-aided
manufacturing). CAM software takes the design you created with the CAD software and
converts it into a “language” called G-Code. This G-
Code is then used by the final type of software,
Control. Control software is the actual application
that talks to your CNC machine; it takes the G-Code
from the CAM software and uses it to send the
proper electrical signals (via the breakout board) to
the three motors.
The Mach3 Control Software is a control
application, It’s from ArtSoft USA and is available
in a free version and a commercial version. Both
versions are identical, but the free version
is going to limit you to 500 lines of G-Code. Figure 42, Main Screen of Mach3
CNC Pumpkin Carver Adam J Frueh
27
When everything is wired on the electronic board, when then connect the computer to
the breakout board using a male-to-male 25-pin cable.
Figure 43, Computer step up Figure 44, Easy CAM
Figure 45, Electronic board
hung up and wired
CNC Pumpkin Carver Adam J Frueh
28
Figure 48, Gear Train
Critical Design Components
By itself, the Pumpkin carver’s parts and components are not heavy enough to cause
failure with the material I’m building with, sheet metal and steel gears. I’ll be using abs
plastic for a few none load bearing parts. This is not designed to hold and drill metal or
wood, just fleshy fruit materials. Pumpkins can weight on average 18 pounds, and I’ll be
designing this for a max load of 30 lbs. Therefore we will need to prevent as much deflection
in our design as possible. Also the hand crank device will need a gear ratio that will allow
ease of use to lift the material.
COMPONENT ONE, BOTTOM VICE
Description: Cantilever
Purpose: Lift and hold material into place
Safety Factor: 2
Load: Static, Moment, 16N at Motor Mount, 130N at the end, 2X factor
of saftey
Figure 46, Deflection visualization
Conclusion: component passes, Max deflection is .01823inchs
and will not be a concern.
COMPONENT TWO, GEAR TRAIN
Description: one timing belt link, one gear link, and two diameter changes
Purpose: Centers both top and bottom platforms
Gear ratio: turn 200N of force into 45N
N1 = 72teeth, 3in Pitch diameter
N2 = 76teeth, 4.72 Pd
N3 = 20teeth, 1.25 Pd
N4 = 48grooves, 3.056 Pd
N5 = 24 grooves, 1.528 Pd
N6 = 3 in Crank wheel
Gear ratio equation: 𝑀𝑣 = (−𝑁2
𝑁3) (−
𝑁4
𝑁5)
𝑀𝑣 = (−76
20) (−
48
24) = 7.6
Figure 47, deflection
scale
CNC Pumpkin Carver Adam J Frueh
29
Central Gear Moment: 200𝑁 × 3𝑖𝑛 = 600𝑁in
After Gear Train: 600𝑁 ×1
7.6= 78.94𝑁
Minimum Crank Moment: 78.94𝑁𝑖𝑛
3𝑖𝑛= 26.31𝑁
Conclustion: Gear Train passes the 45N force required.
COMPONENTS THREE AND FOUR, TIMING BELT CENTER DISTANCE
Description: Two timing belts pulleys positioning
Purpose: Determining bearing mounting positions for no slack blet
Distance Targets: 7in and 9.5in
Originally the supplies website had a center distance calculator to figure out the optimal
distance and belt choice. The actual Distances are Vice platform belt Desired: 9.5 in Actual: 9.587 in X-Axis Belt Desired: 7 Actual: 6.9151in C=Center Distance (in) L=Belt Length (in) = pNB p=Pitch of Belt (in) NB =Number of Teeth on belt = L/p N1=Number of Teeth (grooves) on larger pulley N2=Number of Teeth (grooves) on smaller pulley
=One half angle of wrap on smaller pulley (radians)
=/2 – = angle between straight portion of belt and line of centers (radians)
R1=Pitch Radius of larger pulley (in) = (N1) p/2
R2=Pitch Radius of smaller pulley (in) = (N2) p/2
=3.14159 (ratio of circumference to diameter of circle)
Nomenclature And Basic Equations
2C sin = L – (R1 + R2) – ( – 2) (R1 – R2)
𝐶 = 𝐿 – 𝜋 (𝑅1 + 𝑅2)– (𝜋 – 2𝜙)(𝑅1 – 𝑅2)
2𝑠𝑖𝑛𝜙
Exact Center Distance Determination – Unequal Pulleys The exact equation is as follows: 𝐶 = (1/2)𝜙 [(𝑁𝐵 – 𝑁1) + 𝑘(𝑁1 – 𝑁2)]
where 𝑘 = (– 1) [𝑡𝑎𝑛(– 𝜋 – – 𝜙) + 𝜙 ] is determined from:
1
𝜋(𝑡𝑎𝑛𝜙 − 𝜙) =
(𝑁𝐵 – 𝑁1)
(𝑁1−𝑁2)
CNC Pumpkin Carver Adam J Frueh
30
Figure 49, Center Distance
COMPONENT FIVE, COMPRESSION SPRINGS
Description: Spring mechanism attached to the spindle. Calculate strength
Purpose: Eliminate the need for feedback signals to the controller.
Details: Because a Pumpkin and other possible mediums have a drastically uneven surface
we need a way to keep the z-axis in contact with the surface. The expensive way to do this is
have a feedback signal to the controller with surface distances, typically with CNC machines
this will cause a delay for travel thereby lengthen the process time.
However this could be easily fixed as long as the tool is able to “float” on the surface. A
spring mechanism could achieve this. In theory the tool would fully compress against the
surface triggering a limit switch. Then the z-axis would back of half the compression length.
The result is a tool pressing against the medium. If an uneven surface is more than the
compression distance allow then the limit switch will be activated given a little more room
for moment in that direction
Alpha: Assume frictionless, over engineer
Weight: 5lb
SF:2
10lb ~ 4.53 kg
𝑚𝑔𝑐𝑜𝑠(𝜃) = 𝑁 At 30° 4.53 × 9.81 × 𝑐𝑜𝑠(30) = 38.5𝑁
At 0° 4.53 × 9.81 × 𝑐𝑜𝑠(0) = 44.439𝑁
2 Springs
Choice: Music Wire Precision Compression Spring
Zinc-Plated, 1.5" Length, .48" OD, .063" Wire
Load: 22.94 lb
Conclusion: Two should be enough force
CNC Pumpkin Carver Adam J Frueh
31
Problem: Testing shows the force is far more than necessary to compress.
This error accorded because I converted to Newtons and never converted back.
Solution: Bought several springs to test.
Final Choice: 6lbs/inch rating
Figure 50, Spring mechanism
CNC Pumpkin Carver Adam J Frueh
32
Manufacturing
Fabricating the CNC machine was a huge undertaking, more than I thought it would be.
Several things were changed during the process because they would be too difficult or we
didn’t have the methods available. Regardless, I was able to put together all of the
mechanical components and mechanism. These were made similar to how the design process
went however all at once instead of one element at a time
STRUCTURE
First put together was the outer frame, I did
this because I was going to be aligning everything
and they were going to need a place to be hooked
up to first.
This step was simple, starting with the floor I
installed legs at the same time as mounting the tall
corner beams. The beams are attached to the legs
with several metal corner brackets. This goes the Figure 51, Front view in the works
same for the roof.
For easier caring, I’m attached two sets of
handles to the beams.
Figure 52, Left Side view in the works
CNC Pumpkin Carver Adam J Frueh
33
Z-AXIS - CARRIAGE
The first main component fabricated, like in
the design process is the Z-Axis Carriage.
The clamps are made in the 3D printers and
they are handle together with nuts, spring washers,
and the threaded rods.
Figure 53, Dremel and Clamps
Next was fabricating these sheet metal pieces,
attaching them, the BRAs, and the rack on the top.
This took about 3 days to complete. I’ll be saying this
a lot from now on but the hardest thing about this
projects build is aligning parts and properly drilling
holes. Even then I wasn’t getting smooth spring
action and instead getting binding. After a little
tinkering and grinding of some thread I achieved very
nice linear action.
Figure 54, Complete Housing
The carriage was built alongside the z-axis and
the y-axis. Built as a box, the brackets holding it
together were slightly bent so the box would hold
pressure on the z-axis BRAs. This eliminated some
tolerance issues.
The motor was then mounting and given small
slots so positioning on the rack could be dialed in.
Also attached now is the curved rail sliders seen on
the sides.
Figure 55, Z – Axis Carriage
It was at this point that I recognized some issues.
My designs were very dependent of accuracy of the
components. The straightness and angles of these
even slight off would cause some problems. In a few
instances it wouldn’t be an issue, many cutting and
drills I could make accurately in the shop but since I
needed more time than the shop was open much of
this was made by hand and with a power drill. The
biggest fault came when fabricating the Y-Axis
connections Figure 56, Brackets
CNC Pumpkin Carver Adam J Frueh
34
Y-AXIS – CURVED RAIL AND LIFT
My biggest issue came after mounting these rail to
in the figure #. They were mounted with gorilla glue like
many other pieces in this build but I quickly noticed
how impossible it would be to align these with the linear
bearing on the lead screw platform. There was no trying
to make it work, I ended up breaking the blocks and lost
an expense linear bearing.
However I found a good solution I should have
thought about before. I removed the guess work with
aligning the rails and sampling lifted them with the new
platform seen in figure #. My biggest worry about doing
this before is the platform would simply rotate. Well it
was an easy fix to put a rail behind the platform to
prevent this.
Figure 57, gluing the rails.
After do this and connecting the y axis motor on
the roof the whole thing just came together and
had smooth motion.
Figure 58, Final lead screw platform
CNC Pumpkin Carver Adam J Frueh
35
X-AXIS – PLATFORM AND VICE
The X-Axis had its own issues. The first step was
constructing the mounting arms. They are made out of
sheet metal with hammered flanges to prevent
bending. The top arm only has a rotating point. The
lower arm has this but also holds the x-axis motor.
The issues with this build first arrised in aligning
the rails with the BRA rails and have them both
straight. All while trying to mesh the two with Figure 59 Top Mounting Arm
a central gear. After a very late night I discovered the
rails were crooked. This had set me back a whole day,
thou at least I knew what went wrong. Imagine trying
to sandwich these arms together, align a gear and
bracket the frame into the machine.
Even after I successful put the x-axis into the
chamber, I had discovered I was about half an inch
further back then I needed to be.
Figure 60, Bottom Arm
Figure 61, Front wall w/ rails Figure 62, Back Wall, w/ rails Figure 63, BRA in place
The rest was simple, attaching the gears train and the belt to the back and transferring the
motion to the front. With a drive shaft thou even this was misaligned
CNC Pumpkin Carver Adam J Frueh
36
Figure 64, Complete Assembly
Testing
Everything mechanical is in place to
work, however I can’t get the breakout
board to talk to the motors. I believe this is
because I don’t have a complete
connection with the driver or improper
wiring. I tired following the websites
instructions but they were made for another
set of electronics. These are very similar
but do have some differences. After
contacting the company they have had this
issue before and are working to release
instructions for this product. What they
told me is to have a professional look at it.
Figure 65, Electronic
Panel in place
CNC Pumpkin Carver Adam J Frueh
37
Conclusion
It’s hard to judge the failure of success of this project, since it’s uncomplete with no time
left. I plan to make this work, I might be able to take it to a train electrician, but it would be
simpler to ether wait for the company to release the instruction or to exchange the drivers and
other electronic for the parts they have instructions for.
On what I can judge, everything mechanical is running smoothly with no binding. Each
axis when manually moved act like they should. The biggest issue I see is alignment. The
curved rails are not centered to the vice’s center point. This would mess with the final image
and cause the CNC machine to run slightly awkward on a pumpkins surface.
Knowing what I know now I wouldn’t have constructed this out of wood. I would have
shoveled out the extra bucks to have the panels cut and drilled with precision out of sheet
metal like the original plan. Too much time was wasted in construction and alignment that
could have gone to figuring out the electrically work.
This project simply had two much for just me to do. I could have seen this split into a
two person project. This isn’t the end of the Pumpkin Carver, I plan to complete this in my
spare time and hopefully finish by this next Halloween. This might also be something a
future student would want to work on.
Works Cited
1. The safety of pumpkin carving tools. Marcus, Alexander M, Green, Jason K and
Werner, Frederick W. 6, s.l. : Elsevier Inc, 2004, Preventive Medicine, Vol. 38, pp. 799 -
803. 0091-7435.
2. Pumpkin carving as an exercise in design process thinking. Genereux, William E and
Lewis, Katrina M. Salina, KS : IEEE, 2014. 2014 IEEE Frontiers in Education Conference
(FIE) Proceedings. Vols. 2015-, pp. 1 - 7. 1539-4565.
3. Latchford, Teresa. Don't let pumpkin carving become scary. Newmarket Era-Banner.
7th, Oct 25, 2015, 0844-4072, p. 1.
4. Carlson, Meghan. Lifestyle: The Realistic Person's guide to Pumpkin Carving. Julep.
NEMA 17 motor, 62oz-in 1/4" duel Shaft 19.95 1 19.95
NEMA 23 motor, 100oz-in 24.95 2 49.9
With Relay (Breakout) 28.5 1 28.5
2.5 AMP Motor Driver 45 3 135
Adjustable Rotary Limit Switch 13.95 1 13.95
Limit Switch, 6/pack 30 1 30
E-Stop 14.95 1 14.95
Motion 20 AWG CABLE 1.5 15 22.5
402.56
725.1
CNC Pumpkin Carver Adam J Frueh
42
E. SCHEDULE
TASKS 8/24
/201
58/
31/2
015
9/7/
2015
9/14
/201
5
9/21
/201
59/
28/2
015
10/5
/201
510
/12/
2015
10/1
9/20
1510
/26/
2015
11/2
/201
511
/9/2
015
11/1
6/20
1511
/23/
2015
11/3
0/20
1512
/7/2
015
12/1
4/20
1512
/21/
2015
12/2
8/20
151/
4/20
16
1/11
/201
61/
18/2
016
1/25
/201
62/
1/20
16
2/8/
2016
2/15
/201
6
2/22
/201
62/
29/2
016
3/7/
2016
3/14
/201
6
3/21
/201
63/
28/2
016
4/4/
2016
4/11
/201
6
4/18
/201
64/
25/2
016
Design I
Design Draft
Final Design Report
Design II
Proof of Design Agree (advisor)
Concepts/Selection (advisor)
3D Model - (name sub-assmby)
3D Model - (name sub-assmby)
Design Presentation
Design III
Manufacture
Test
Tech Expo
Project Presentation
Name(s)Project title
Sun - SatDesign presentation to faculty (12 min) Jan 27 – 31Design report to advisor Feb 3- 7Demonstration to advisor Mar 24-28 Tech Expo(Thur. Apr. 3)Project presention to faculty (15 min) Apr 7 - 11Project report to advisor for review before library submission Apr 14 – 18Library pdf file in BB (fall course link) Wed. Apr 23
Schedule Columns are by week starting with the first design task (Concept sketches/selection)Columns give datesTasks are broken into 1-2 week intervalsEach task line has 2 rows in the spreadsheet to allow for the actual interval to be addedDeadlines are typed as dates in the interval (earliest option)Deadlines match the MET and advisor requirementsOne deadline is the Proof of Design AgreementParts/materials are ordered as early as possible Readable (break into pages if needed)Informative heading
Table 4 Schedule
TASKS 8/24
/201
58/
31/2
015
9/7/
2015
9/14
/201
5
9/21
/201
59/
28/2
015
10/5
/201
510
/12/
2015
10/1
9/20
1510
/26/
2015
11/2
/201
511
/9/2
015
11/1
6/20
1511
/23/
2015
11/3
0/20
1512
/7/2
015
12/1
4/20
1512
/21/
2015
12/2
8/20
151/
4/20
16
1/11
/201
61/
18/2
016
1/25
/201
62/
1/20
16
2/8/
2016
2/15
/201
6
2/22
/201
62/
29/2
016
3/7/
2016
3/14
/201
6
3/21
/201
63/
28/2
016
4/4/
2016
4/11
/201
6
4/18
/201
64/
25/2
016
Design I
Design Draft
Final Design Report
Design II
Proof of Design Agree (advisor)
Concepts/Selection (advisor)
3D Model - (name sub-assmby)
3D Model - (name sub-assmby)
Design Presentation
Design III
Manufacture
Test
Tech Expo
Project Presentation
Name(s)Project title
Sun - SatDesign presentation to faculty (12 min) Jan 27 – 31Design report to advisor Feb 3- 7Demonstration to advisor Mar 24-28 Tech Expo(Thur. Apr. 3)Project presention to faculty (15 min) Apr 7 - 11Project report to advisor for review before library submission Apr 14 – 18Library pdf file in BB (fall course link) Wed. Apr 23
Schedule Columns are by week starting with the first design task (Concept sketches/selection)Columns give datesTasks are broken into 1-2 week intervalsEach task line has 2 rows in the spreadsheet to allow for the actual interval to be addedDeadlines are typed as dates in the interval (earliest option)Deadlines match the MET and advisor requirementsOne deadline is the Proof of Design AgreementParts/materials are ordered as early as possible Readable (break into pages if needed)Informative heading
CNC Pumpkin Carver Adam J Frueh
43
F. BUDGET
From my sources a small CNC machine can be built for at least $390. But can be as high
as $3000 dollars. But the average someone might spend is around $700-800, therefore I’m