lecture-2

Mechanical-Engineering BasedDesign of the Transporter:

Device Geometry, Drive Systems, Power Requirements, Friction Coefficients

R. S. Shaefer

MAE-162D

Mechanical & Aerospace Engineering Department

University of California Los Angeles

Winter 2014

1/15/2014 2MAE-162D R. S. Shaefer, W14

TOPICS

Machine-shop Training

Project Updates

Teams

Design Concept Report

Conceptual Design Decisions

Vehicle Climbing a Ramp

Wheel Friction Coefficients

Motor Power Requirements

Gear Ratio, Battery Life

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Machine-shop Training

Project Updates

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Project Updates Instead of 5 billiard balls ONLY ONE will be placed in the starting platform.

Teams have to find and move only one randomly placed billiard ball and transport and deliver it to the collection bin and return to the platform (1

roundtrip).

With only one single ball to be transported, the dimensions of the starting platform might not be increased from the current 24 x 24 inches (final

dimensions will be announced by the next lecture).

$350 will be deducted from your teams budget if the IO controller board is damaged (fried).

Water jet use has to be OKd by the TAs or Instructors. In addition $2.50 per minute will be charged for water jet usage.

Use of On/off switch: If a transporter can achieve automated start/stop, without using the on/off switch

more than once during the entire trial, the total number of balls delivered will be

adjusted up by 15%.

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TEAMS

Formed based on Student Survey

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Group 1

Chinn, James

Dashti, Parisa

Petersen, Daniel

Ruff, Carlton

Group 2

Ahn, Min Sung

Hruska, Dylan

Padula, Andrew

Provinchain, Adam

Wong, Brian

Group 3

Ahn, Christopher

Godina, Everardo

Liu, Hsuan-Chen

Pourati, Pouyan

Wong, Tsz

Group 4

Barnett, Kaleen

Kampouridis, Christos

Lee, Jong Hak

Sakamoto, Ryan

Zhang, Yuheng

Group 6

Chen, Joshua

Chow, Kevin

Johnston, Timothy

Okano, Jillian

Ruiz, Hector

Group 5

Apelacio, John Carlo

Brett, Bowers

Calderon, Daniel

Garg Archit

Yang, Brandon

Group 7

Datta, Sanjeev

Matsunami, Kameron

Rechnitz, Jared

Voyen, Nicole

Yagi, Yuki

Group 8

Dissanayake, Ravisha

Jimenez, Marlon

Knox, Allison

Lloyd, James

Stromlund, Adam

Tuesd

ayMAE-162D/E Team Roster (01/16/14)

1/15/2014 7MAE-162D R. S. Shaefer, W14

Group 9 (No Downeys)

Chan, Brandon

Hee, Bryan

Kitchener, Bryan

Law, Jonathan

Stern, Brian

Tran, Nina

Group 10

Chiu, Caspar

Downey, Brian

Huang, Wen-Chieh

Meirovitch, Daniel

Shafer, Melissa

Group 11

Hsu, Jonathan

Phan, Tri

Sarabian, Chareena

Sundin, Stephen

Vasko, David

Group 12

Delgado, Kristine

Flynn, Michael

Gloutak, Dasha

Hollins, Asya

Song, James

Group 14

Jones, Luke

Lee, Thomas

McKittrick, Michael

Neff, Samuel

Warwick, Mark

Group 13

Edstrom, Mark

Le, Dai

Liu, Kevin

Tate, Austin

Winters, Zachary

Group 15

Kinoshita, Alan

Lam, Betty

Lee, Joseph

Levin, Cole

Sun, Daniel

Group 16

Chung, Boris

Coleman, Matthew

Dimapasoc, Brando

Holden, Emily

Kurihara, Matthew

Wed

nesd

ay

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Group 17

Chatterjee, Shinjan

Hsu, Eric

Ricciardelli, Albert

Shin, Seung Ryul

Suh, Jungwoo

Group 18

Garcia, Aurora

Nishioka, Crystal

Tang, Yang

Wood, Kevin

Yamayoshi, Itsui

Group 19

Hakobyan, Vardan

Pajuelo Lopez, Paulo

Partusch, Vincent

Ramirez, Ricardo

Tang, Emily

Group 21

Cooper, Andwele

Cooper, Cody

Moore, Danielle

Saad, Hassan

Sheu, Oliver

Group 20

August-Schmidt, Alex

Hwang, Jae Woong

Kwak, Wooyoung

Wong, Jameson

Friday

9MAE-162D R. S. Shaefer, W14

Team Structure

Establish who will be :

o Project Manager, Mechatronics Engineer, Systems

Engineer and Cognizant Engineer

Upload an excel spreadsheet with the following structure by next lecture:

(template has been uploaded to courseweb)

Name the excel spreadsheet: Team-YOUR#-Structure.xlsx

Team #

Project Manager Name email address

Mechatronics Engr. Name email address

Systems Engr. Name email address

Cognizant Engr. Name email address



1/16/2014 10MAE-162D R. S. Shaefer, W14

Conceptual Design Report(due next Friday, Jan. 24, 2014)


Conceptual Design Outline

Report Word-2013 template has been uploaded to courseweb

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Examples of Concept Sketches

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Examples of Acceptable Hand-sketches

MAE-94 Fall 2013


Developing Design Concepts

Meet at least two times between now and next Friday and establish team structure

At this stage you are developing the mechanical portion of your project (the control and feedback will come later)

Therefore, assume your device has found the ball and you are only concerned with designing a product that will deliver the ball to the drop-off bin.

Also, do not be concerned about how you will find the entrance to the ramp.

However, you need to think about how the device will:

change directions,

initiate the move up the ramp,

turns the ramp corners (mechanical aspect only),

stops in the unloading platform, and

releases the ball into the bin.

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Design Process

Need

Conceptual Design

Preliminary Design

Detailed Design

Product Specifications

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Lecture TOPICS

Mechanical Engineering Based Design :

1. Design Concept Overall Geometry ?

2. Drive System for a Vehicle Climbing

a Ramp ?

3. Wheel Friction Coefficients ?

4. Motor Power Requirements ?

5. Gear Ratio, Battery Life ?

1/15/2014 17MAE-162D R. S. Shaefer, W14

Maximize speed of delivery

Limitations: 5 min

Budget: $350

Need to establish

necessary traction

force (friction

coefficient)

Want to supply sufficient traction force

at minimum required power

Need to know

required power:

to get the right motor

Length ?

Width ?

Height ?

Wheelbase & Track ?Wheel size &

Material?

1/15/2014 18MAE-162D R. S. Shaefer, W14

Conceptual Design Decisions

For the conceptual design a number of primary design parameters have to be established:

Overall device dimensions (height, length, width)

Cargo delivery system (mechanism)

Speed and load capacity (device + cargo) (time per run)

Drive system (AWD, FWD, RWD)

Wheel size (diameter)

Wheel position (track & wheel base)

Wheel material (necessary friction to climb)

Motor Power minimum requirements (speed and # of runs)

Gear Ratio (speed/power)

Choice of design parameters must be based on engineering fundamentals (todays lecture)

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Vehicle Climbing an Incline Plane Examine the physics behind wheeled vehicles climbing

slopes for:

Front Wheel Drive (FWD)

Rear Wheel Drive (RWD)

Four Wheel Drive (AWD)

Step (over an obstacle)

Questions:

What is the minimum wheel/surface friction coefficient necessary to avoid slipping, what is the tip-over angle?

What is the minimum Tractional Force necessary to climb?

What is the appropriate drive system: FWD, RWD, or AWD?

http://hpwizard.com/car-

performance.html

Vehicle Driving Up a Slope

Fm = gravitational force on the machine

Nf = normal force of both front wheels

Nr = normal force of both rear wheels

Ftf = Nf Tractional force of both FWs, caused by static friction Ftr = Nr Tractional force of both RWs, caused by static friction

= coefficient of friction, q = angle of incline plane

x

L

LC

y q

Ftf

Ftr

Nr

Nf

Fmhc

FW

RW

L = distance between FW and RW

Lc = distance between RW & center of mass

hc = height of the center of mass

20

Front and Rear Wheel Tractive Forces (Ftf, Ftr)

0 : 0

0 : 0

( )

:

y r f m

r m f m C

m C mf

m C mr

tr r

tf f

F N N F cos

M F h sin N L F L cos

F L cos F h sinN

L

F L L cos F h sinN

L

R ear and Front Tractive Forces

F N

F N

q

q q

q q

q q

Using Free Body Diagram:

21

What happens when Nf zero ?

x

L

LC

y q

Ftf

Ftr

Nr

Fmhc

FW

RW

Nf 0

Nf

22

Tip-over Angle

When designing your transporter the location of the center of gravity of your system has to be established for the Preliminary Design Report): use SolidWorks to establish the coordinates of the center of gravity of your

device assign correct materials and include the cargo

Ramp angles are set the COM (hc, Lc) and L of your transporter can be optimized.

Write a simple program or use an excel spread-sheet to modify dimensions to optimize dimensions of your design

max

0 : 0m C m cf

C

F L cos F h sinN

L

Lh

tan

q q

q

tan qmax = Lc / hmax

Tip-over angle when Nf = 0: q = qmax and maximum COM* height h = hmax

*COM Center of Mass 23

Required Friction Coefficient for AWD, FWD, RWD

0 : 0

0 : 0

0 : 0

0 : 0

( )

( )( )

x r f m

x r r f f m

y r f m

r m f m C

m C mf

m C mr

r f C r

F N N F sin

F N N F sin

F N N F cos

M F h sin N L F L cos

F L cos F h sinN

L

F L L cos F h sinN

L

L sin

h sin L cos L cos

T

q

q

q

q q

q q

q q

q

q q q

1

: ;

: tan

Tf f Tr r

C

ractive Forces F N F N

LTipping angle

h

q

f r

f r

f r

FWD set =1 and =0

RWD set =0 and =1

AWD set =1 and =1

Required friction

coefficient based on

DRIVE SYSTEM &

Device dimensions24

COEFFICIENT OF FRICTION

FOR

AWD, FWD, & RWD

Required Tractive Forces

FTf = Nf Tractional force of both FWsFTr = Nr Tractional force of both RWs

What is the minimum required (= ?)

for a given transporter drive system and ramp slope q

x

L

LC

y q

FTf

FTr

Nr

Nf

Fmhc

FW

RW

26

Estimate Required Wheel Coefficient of Friction

The necessary static coefficient of friction () depends on powering mode:

Four Wheel Drive 4WD

Front Wheel Drive FWD

Rear Wheel Drive RWD

4 4

4

tr tf m

r WD f WD m

WD

F F F sin

N N F sin

tan

q

q

q

4 Wheel Drive 4WD

Minimize required coefficient of friction depends only on angle?

Decrease by decreasing the incline (cant ramp slope is set !)

(slide 24)

27

Estimating Necessary Coefficient of Friction

1

f FWD m

FWDC

N F sin

L h

L tan L

q

q

Front Wheel Drive FWD

How can the required coefficient of friction be minimized?

Move the center of gravity forward

Shorten the wheelbase (L)

Lower the height of the center of gravity (hc)

28

Estimating Necessary Coefficient of Friction

1

r RWD m

RWDC

N F sin

L L h

L tan L

q

q

Rear Wheel Drive RWD

What can be modified to allow for a lower coefficient of friction?

Move the center of gravity towards the RWs (reduce Lc)

Increase the wheelbase (L)

Raise the height (hc) of the center of gravity

29

Required Coefficient of Friction

Depending on drive-system (FWD or RWD) the required wheel friction coefficient can be

minimized by adjusting device geometry:

L Lc hc4WD NA NA NA

FWD RWD

:

Tf f

Tr r

Tractive Forces

F N

F N

1: tan C

LTipping

hq

30

Required Coefficient of Friction

The distance of the Center of Gravity from the rear wheels can be chosen such that either RWD and FWDwill require the same minimum coefficient of friction.

For equal FWD and RWD minimum coefficient of frictions we can solve for LC-F/RWD :

Positioning the Center of Gravity at LC-F/RWD provides design flexibility

/ tan2

FWD RWD

C F RWD

LL h

q

31

Determining Optimum Drive System

Example:

Given device dimensions L, h, and slope What would be the best drive

system: FWD, RWD, or AWD

Investigate the impact of the distance of the CG from the rear wheels (Lc).

Dimensions are as follows: Wheel base (L) 12 inch Height of CG (h) 7 inch Angle (theta) 10o

On the next slide we compare the friction coefficients for FWD, RWD, and AWD

32

1/15/2014 33MAE-162D R. S. Shaefer, W14

Minimum Required Friction Coeff. The graph shows that the required friction coefficients -FWD and -RWD are

equal for an Lc-F/RWD = 7.234 inches from the rear wheels:

The lowest required minimum coeff. of friction is for AWD (which would require the smallest tractive force (FT) to drive the vehicle up the slope). However the

additional weight, complexity, and cost of an AWD system has to be considered.

Device Dims.:

L = 12 inch

h = 7 inch

q = 10o

1/15/2014 34MAE-162D R. S. Shaefer, W14

For the Preliminary Design Decide on the Best Drive System

Compare the friction coefficients for FWD, RWD, and AWD and pick the smallest one, which requires the least amount of power to drive the vehicle up the slope.

Finally, compare the estimated required minimum coefficient of friction with your measured wheel/surface coefficient (-Wheel) to guarantee that the vehicle will not skid backwards.

1. First, measure the coefficient of

friction (Slide #19) between your

wheel and the sloped surface:

-Wheel

2. Next, determine the coefficient of

frictions between your vehicle and

the slope for the drive systems:

FWD, RWD, AWD

MEASURING COEFFICIENT OF

FRICTION

Measure Wheel Coefficient of Friction

2 2

cosm mN F F sin

htan

L h

q q

q

Coefficient of Friction:

Perform a simple inclined plane test

Use hypotenuse length ~ 50 cm

Raise end of ramp until test car slips

Measure h and calculate

Coefficient of friction

Plywood

Wheel surface along grain across grain

Plain 0.45 0.47

Knurled 0.47 0.48

Sandpaper covered 0.91 0.92

36

1/15/2014 37MAE-162D R. S. Shaefer, W14

Fraction of Weight on Front/Rear Wheels on an Incline

( )

( )

m C mf

f Cf

m

m C mr

Crr

m

F L cos F h sinN

L

N L cos h sin

F L

F L L cos F h sinN

L

L L cos h sinN

F L

q q

q q

q q

q q

Dividing the normal forces on the wheels (slide 26)

by the total weight gives fractional distribution of

weight (r,f) :

1/15/2014 38MAE-162D R. S. Shaefer, W14

Measure Wheel Coefficient of Friction

Assuming you have decided the following for your concept:

4-wheel drive, 2-wheel rear, or 2-wheel front drive

Maximum size of the device

Amount of rice per run

Approximate time to deliver the load

You have estimated the minimum coefficient of friction required to go up the plywood ramp

You can now try different materials and see if they will provide the necessary coefficient of friction

You can approximate the overall dimension and coordinates of the center of gravity

And you can now estimated the required total power/torque necessary to deliver the load

And therefore you can start looking at motors, and decide how many motors you should use.

POWER TO MOVE A VEHICLE

Required Power to Move a Vehicle & Minimum min

2

2 efficiency

at F vx v at F ma P

For a machine of mass m to move a distance x under constant

acceleration a in time t:

2

2 2 3

2 2 2 4

efficiency

x x xm mxa v F P

t t t t

Solving for the power consumed in terms of m, x, and t: :

min( )F

F N F mgmg

If the percent weight of the vehicle over the drive wheels is , then the minimum coefficient of friction between the drive wheels and the ground is:

Create an excel spread-sheet to calculate a (m/s2), F (N), min, vmax, P (Watts)40

22 efficiency

at F vx v at F ma P

2

2 2 3

2 2 2 4

efficiency

x x xm mxa v F P

t t t t

min( )F

F N F mgmg

Excel Spread-sheet to calculate a(m/s2), F(N), min, vmax, P (W)

Distance to move, x (m) 2.0 m

Desired move time, t (sec) 3.0 s

Mass, m (kg) 3.0 kg

Estimated system efficiency, eta 50% --

% vehicle weight over drive wheels, beta 50% --

Power per motor, wm (Watts) 2.0 W

Acceleration required, a (m/s 2^, g's) 0.44 m/s2 0.05 g's

Force required, F (N) 1.33 N

Min. coeff. of friction drive wheels to ground, mu_min 0.09 --

Maximum velocity (at end of move), v (m/s) 1.33 m/s

Power required, P (Watts) 3.56 W

Motors required 2 --

Enters numbers in BOLD, Results in RED

Power Required to Move

To estimate the power to move a mass m a distance x with constant

41

Example: Choosing a Go-Kart Motor

The challenge:

Build a Go-Kart that goes up a 30o hill at 4 mph (m = 90 lb, wheel diameter is 10 inch).

You are given a 9 amp-hour battery to power the Go-Kart.

For the motor you have two options :

Motor-1: Electric motor, which draws about 20 A to produce1 Hp with a torque of 60 N-m at 150 rpm. The motor costs $167.99.

Motor-2: Electric motor that puts out 0.4 Hp at 2500 rpm drawing ~ 5 A. The motor costs $37.59.

Which motor will you choose and why?42

Required Motor Power

Given: Electric Motor: 0.4 Hp at 2500 rpm

Hill Slope: 30o

Design Requirements: Max speed 4 mph (up a hill of 30o)

Wheel diameter 10 in

Total Mass 90 lb

Approach: First determine the necessary POWER needed to move the

Go-kart up the hill.

Next, determine the gear ratio to achieve the necessary torque at the wheels.

43

Estimating Required Power

Force to move the Go-kart :

Freq: total required force

FW : vertical component of weight

Ff : friction force

Frol: rolling force

FInertia: overcome inertia (assume v = 0.25 m/s in 1 s ainertia =0.25 m/s2)

Estimated the required force using:

f = 0.35

rol = 0.015

Required Power:

v is steady state velocity

(vtan = r w; w in rad/s))

req Inertia W f rolF F F F F

sin

cos

337.00 N

req Inertia

f rol

F ma mg

mg

q

q

337.00 N 1.79 m/s

602.56 W

req reqP F v

44

Estimate Required Torque for Go-Kart & Motor

Torque Power Relation: P is the motor power

w is the angular velocity

Motor produces 0.4 Hp at 2500 rpm*:

For a 5 inch radius wheel at 4 mph*:

Necessary torque to drive the cart at 4 mph:

mm m m m

m

PP T Tw

w

1.15mT N m

1.79 /14.08 / 134.45

0.13

v m srad s rpm

r mw

1 rad/s = (2/60) rpm req mT T

602.5642.80

14.08 /

req

req

P WT N m

rad sw

*Note that the units actually come out as 1/s (Hz);

however, radians are a suppressed unit

with regards to angular velocity

so we write (rad)/s45

Determine the Gear Ratio and Battery Lifetime

TMotor is less than TRequired

Requires gearing determine gear ratio (GR):

1.14 42.80m reqT N m T N m

46

Determine the Gear Ratio and Battery Lifetime

Tmotor is less than Trequired

Gear ratio:

Use a gear ratio of 40

Battery Lifetime: Motor currents are rated at 5 A and 20 A each:

1 29 1 48 ; 275

Motor Motor

time time

amp hourB hr min B min

amp

42.8037.56

1.14

req

m

TGR

T

1.14 42.80m reqT N m T N m

47

MOTOR SPEED, POWER, AND

TORQUE

Stall Torque and No-Load Speed

Assuming steady state and no slippage between wheel and ground:

Torque (T):

if r is not :

Stall Torque (ts): The minimum torque needed to completely stop the motor

shaft from rotating (stalling the motor). Units are ft-lbs or Nm.

No-Load Speed (wn): The rotational speed of the motor shaft when there is NO

torque being applied to it. Units are RPM or rad/s

T r

F

(1)T F r

sin (2)T F r q

49

Motor Torque Speed and Power TRADEOFF

Using eq. 1 we can define the following :

The plot of eq. 3 or 4 is calleda torque-speed curve.

Example: A motor has a no-load speed of 95 RPM and a stall-Torque of 0.6 Nm:

T r

F

(3)

or in terms of :

( ) (4)

ss

n

ns

s

TT T

T TT

ww

w

ww

Stall Torque ts )

no-load Speed (wn)

50

Torque -Speed Curves

If we know the torque applied to the motor shaft we can find how fast the motor will rotate.

Or if we know how fast we want the motor to spin, we can find how much torque should be applied.

Stall Torque

no-load Speed

Motor Specs.

often list

no-load Speed

Lo

w P

ow

er

Low Power

Max Power

m m m

mm

m

P T

PT

w

w

51

Motor Power

Recall:

If we multiply eq. 3 by w or eq. 4 by T we get power as a functions of either torque or velocity:

These quadratic equations are shown on the next slide:

(5)P T w

2

2

( ) (6)

( ) (7)

ss

n

nn

s

TP T

P T T TT

w w ww

ww

(3)

( ) (4)

ss

n

ns

s

TT T

T TT

ww

ww

52

Motor Power as functions of w orT :

There is a maximum power for a given range of speed and torque.

For optimum performance, the motor should be operating at torque and speed corresponding to the maximum power.

The optimum torque and speed are at about half Ts and wn respectively.

The maximum power available is (Ts wn )/4 53

Maximum Velocity and Torque

If k (speed-torque slope) is known then relate torque, power, and velocity:

max

max

max

2

max

max

max smax max

0 2

; 2 2

P P

k

k

P k

Pk

t w t

t

w

t w w t w

w tw

w tw t

54

Motor Power

Given: tmax= 9 N-mm, wmax= 14000 rpm, tw slope (k) = - 0.006 the motor torque and power for w-increments of 200 rpm are:

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0

1

2

3

4

5

6

7

8

9

10

0 2000 4000 6000 8000 10000 12000 14000

Po

we

r (W

atts)

To

rqu

e (

N-m

m)

Motor Speed (rpm)

Torque (N-mm)

Power (Watts)

Note: max

power is not

at maximum

torque or

speed

55

Concept Design Procedure

After you have made the following concept design decisions:

Drive system (4-wheel, 2-wheel rear, or 2-wheel front)

Maximum size of the device (height, length, width)

Cargo weight per run (dont forget weight of the transporter)

Approximate time to deliver a billiard ball (tmax = 2 4 min ?)

You can now refine your conceptual design based on the following mechanical engineering fundamentals:

1. Estimate the minimum coefficient of friction (m) required to climb the

plywood ramp

2. Establish candidate wheel materials provide the necessary m

3. Establish the overall dimension of your device and coordinates of the

center of gravity (L, LC, h)

4. Estimate the required power/torque necessary to deliver the load

5. Research motors, and decide what motor and/or how many you

should use including gearing requirements (use plot torque-speed

curves to estimate maximum torque and RPMs)

6. Approximate battery power consumption (more on this next lecture) 56

1/15/2014 57MAE-162D R. S. Shaefer, W14

Background Slides


Need for Standards: Inch Converter (Mid 19th Century)

Hamburgh - Inch divided into 8 parts. 1 inch 23.2 mmAustrian - Inch divided into 8 parts. 1 inch 25.8 mmItallian - Inch divided into 8 parts. 1 inch 28.3 mmBremen - Inch divided into 10 parts. 1 inch 23.7 mmSwedish - Inch divided into 12 parts. 1 inch 24.3 mmTurkish - Inch divided into 12 parts. 1 inch 31.3 mmBavarian - Inch divided into 12 parts. 1 inch 24.0 mmSpanish - Inch divided into 12 parts. 1 inch 23.0 mm

Portuguese - Inch divided into 12 parts. 1 inch 27.0 mmMoscow - Inch divided into 12 parts. 1 inch 27.7 mmRussian - Vershok divided into 8 parts. 1 vershok 44.1 mmAmsterdam - Inch divided into 12 parts. 1 inch 23.5 mmRhynland - Inch divided into 12 parts. 1 inch 26.1 mmFrench - Inch divided into 12 parts. 1 inch 27.0 mmFr. Metre - Centimetres divided into Millimetres.

English - Inch divided into 32 parts. 1 inch 25.3 mm

The parts of a mill and what they do (1/5)

Parts of a mill and what they do.

Variable Speed Control KnobControls motor speed from 0 to 2800 RPM

HeadstockContains the spindle in two preloaded ball bearings.

SpindleThe spindle is inside the headstock and is driven with a belt running from the motor pulley to a pulley on the rear end of the

spindle shaft. The nose of the spindle is treaded on the outside to

receive chucks and tapered on the inside to receive other

accessories.

Drill ChuckUsed to hold drill bits for drilling holes. (Not to be used to hold end mills!)

Mill TableParts are fixed to the table using a vise, chuck or clamps and moved under the milling cutter using the X- and Y-axis

handwheels.

Mill SaddleThe mill saddle slides in and out (Y-axis) on the mill base. The mill table moves left and right (X-axis) on top of the

saddle.

Headstock SaddleThe saddle on the vertical column that moves the headstock (Z-Axis) up and down by means of a leadscrew and handwheel.

Mill ColumnThe steel dovetailed column that is held to the mill column base and supports the Z-axis saddle and headstock.

LeadscrewThe threaded screws that move the table left/right and in/out as well as the vertical axis up and down. They are driven by handwheels

marked in .001" or .01 mm increments.

Leadscrew Locking LeverLocated on the back side of the vertical column, this locking lever locks against the saddle nut to prevent unwanted

movement of the Z-axis during machining operations. Manual machines are

fitted with a standard on/off locking lever. CNC machines are fitted with an

adjustable locking lever that can be used to control backlash in the Z-axis.

This function is available as an option on any manual mill as well. (P/N

4017U inch or 4117U metric)

GibsTapered plastic gibs are used on each dovetailed axis to take up wear as it occurs. They are slightly wedge shaped. As side-to-side "slop"

develops on an axis, the gib lock is loosened and the gib is pushed a little

further into the gap, taking up the play. These allow the machine to always

be kept as tight as the operator desires. If or when they wear out, they are

very inexpensive to replace.


Mill BaseThe solid base that has the dovetail for the saddle to move in and out on and to which the mill column is attached.

DrawboltGoes through the hole in the spindle to draw chucks and other accessories into the headstock taper inside the spindle. A special washer

locates in on center in the spindle hole.

#1 Morse ArborThe arbor screws into the back of the drill chuck so it can be used in the headstock. It is held in place in the #1 Morse taper with the

drawbolt.

Tommy BarsRound steel bars used to tighten and loosen chucks and other spindle accessories. Sometimes called "Spindle Bars."

Y-axis Locking ScrewA thumbscrew on the side of the base that keeps the saddle from moving in and out when tightened.

X-axis Locking ScrewA screw that goes through the barrel lock on the front of the saddle to lock the table in place during machining operations where

movement is not required or desired.


Backlash LocksThe lock works like tightening two nuts against each other on a threaded shaft to reduce play in the threads.

Backlash is the pause in travel when changing direction of rotation of any threaded crew. Because both sides of the thread don't rub on the nut at the

same time (they would quickly wear out), one surface is pulling or pushing the

nut when the screw is turned.

When you stop and change directions, the screw turns a slight amount while the thread picks up the other side and begins to move the nut in the other

direction. The looser the fit of the threads, the more "backlash" occurs.

In essence, it is the amount you can turn the handwheel in the reverse direction before movement occurs on an axis. An adjustment is provided on the X- and

Y-axes to reduce the leadscrew backlash.

Backlash is not a "fault" of a machine, it is simply a physical reality that must be taken into account when machining. You adjust to a known or acceptable

amount using the locks and then remove it from the machining operation by

always approaching your cut from the same direction with the backlash already

eliminated before the cut begins.


Alignment KeyA precision ground key that fits in a slot in the column saddle to keep the headstock aligned straight up and down. A second

slot is also provided to locate the headstock at 90 for horizontal

milling. Removing this key and rotating the headstock allows bevels to

be cut at any angle. An approximate angle scale is laser engraved into

the saddle for reference.

Headstock Spacer BlockMoves the headstock 1.25" further out from the saddle to increase the "throat" distance (distance between

cutter and column). It is optional on 5000-series mills, standard on

5400-series mills and not needed on 2000-series mills because the ram

can be used to adjust this distance.

V-beltA Kevlar-reinforced Urethane belt that drives the spindle through the pulleys.

2-position PulleyThe normal (rear) position gears the motor down about 2:1 for a maximum speed of about 2800 RPM. The "High

Torque" position (closest to the headstock) gears it about 4:1 for lower

speed but more torque when needed for heavy cuts.


lecture-2

Documents

starting platform

teams budget

billiard balls

water jet use

onoff switch

water jet usage

w14project updates

friction coefficientsr