home made cnc drilling machine

8/9/2019 Home Made CNC Drilling Machine

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Home made CNC drilling machine

CNC drilling machine is a tool which is required for drilling of holesin PCB, thaw it can be used for many other purposes too. The

software communicates with machine via serial port C!"#...C!"$%

of PC. The software wor&s only with machine which has the rightmicro controller built in.

T'B() !* C!NT)NT+

-H'T + CNC /0((N1 "'CHN)2

H!- /!)+ T -!032 C0C4T /)+C0PT!N

"C0! C!NT0!(()0 !P)0'T!N 'N/ 0!4TN) )5'"P()+

'++)"B(N1 TH) PCB

H!- T! C!NN)CT ' +T)PP)0 "!T!02

*0+T +T'0T4P 'N/ C'(B0'T!N

+!*T-'0)

H!- T! "'3) ")CH'NC'( P'0T !* "'CHN)2

C!"P!N)NT+ (+T

/!-N(!'/+

-H'T + CNC /0((N1 "'CHN)2

The name itself (CNC = Computer Numerical Control) says pretty much. The

machine is intended to be used to help hobbyists with their prototyping. Also

if you draw something else with your software, you can easily do other jobsas well. The machine described below functions lie many others. That

means that the computer transmits positions and commands to machine.The machine then e!ecutes desired operation and replies to the computer

when done. "n our case one part of job is done when one hole is drilled. This

machine can#t mill $C%s yet, but "#m woring on it.

H!- /!)+ TH) "'CHN) -!032

The machine " made wors similar lie other machines of this type. "t isconnected to serial port of "%& compatible personal computer and controlled

by program written for &' indows� operating system. The program



transmits data from $C to machine and checs if it#s responding. Themachine replies eery time when operation is done or when computer ass it

if it is powered on. The program first sends coordinate for * a!es, then for +and finally for . After sending last coordinate also the command is sent

which tells the machine what to do with drilling head. That command can

send head towards $C%, it can drill a hole of certain depth, which means thatthe head will go down for certain distance and then moe bac up. "t can

also moe head up or initiali-e it.

The core of machine is simple micro controller AT/C0123, which is fully

filled with program, written with %ascom4123. (%y the way, thans to mr.

&ar Alberts for his wonderful program) The mcu has a lot to do. "t taescare of receiing and sending data, motor direction and pulses needed by

motor controller, current through motors and driller power. "t also calculatesit#s relatie coordinates from absolute ones, sent by computer. "n fact it#s

really busy.

C0C4T /)+C0PT!N

The core of our circuit is well nown micro controller AT/C0/23. "t wors at

30&5-, which isn#t ideal for baud rate generator, but it wors fine. &ost of"67 pins hae e!ternal pull4ups e!cept $3.3 which is used to control current

flow through motor windings. 8eason for this are interference#s generated by

motor current control. The capacitors C39, 3 and 09 are therefor the samereason. $9.3 and $9.0 are used for $C communication.

C0: (:;1n) is used as reset capacitor who#s pull down resistor is in alreadyin micro controller. " thought it maes no sense to put e!ternal electrolytic

capacitor and pull down resistor in such cases. The &A*090 is also well

nown 8'090 leel conerter. These two circuits are powered from <9> lineia 32> -ener diode and ;?12 oltage regulator. " decided for this because

translators ?0/; generate much noise in their power line. <2> power supplyfor ?0/; must be connected e!ternally.

" also included drilling machine#s power supply in my circuit. "t is configured

for 30> motor. "f you use other motor oltages you should adjustcomponents in this circuit, specially 8@3, C3 and power transformer.

At the end there are motor controllers which are well described in 'T#s data

sheets. " should mention that $3, $9 and $: are used to set step mode ofmotorsB half step or full step. ith half step we double motor#s resolution

and e!clude spurious resonance, but we also loose some torue. There arealso two points mared with '$3 and '$0. These are spare connections and

are not used yet.



&icro controller also taes care of motor current. The oltage diider is madewith resistor 00, and trimmer :;18. hen $3.3 is low the diider is

additionally pulled low ia 318 resistor. This way we reduce standby currentto 369 of full current. This way motors stay cool when the machine isn#t in

use. The current through each motor is controlled with :;18 trimmer

potentiometers T$3, T$0 and T$9. The power loss on output chips dependson motor currents and chopper freuency. $robably you will need a smaller

cooler and maybe a little fan on top of it.

The power of power supply reuired by our circuit depends on motors weuse. "n most cases the 9>60A and 2>61.9A $' will do fine. The cable

between $C and driller is usual with two D%/ connectors, male and female.The initiali-ation switches are normal mechanical. " decided so, because they

aren#t sensible to light or dust lie "8.

NoteE if the schematics doesn#t load, hold '5"FT and clic on picture to

sae it to dis and then open it with your faorite image iewer. The same goes for other 5igh resolution images too.

Circuit schematics

"C0! C!NT0!(()0 !P)0'T!N 'N/ 0!4TN) )5'"P()+



7n power on the micro controller first initiali-es all three motors. First it lifts motor on top, to aoid drill breaing. "f the motors are in initial position,

they are moed a little and initiali-ed bac again. The motors run until theyhit their end switch. The mcu then stops that motor and initiali-es ne!t one.

The initiali-ation routine loos lie this.

'Z axis initialization

If P3.5 = 0 Then 'if the end switch is pressed

P1.3 = 1 'set motor direction to C

!or " = 0 To 100

P1.# = 0 'reset C$%C& line

ela( 'wait a moment

P1.# = 1 'set C$%C& )ac*

!or + = 0 To , 'with this loop we set the

ela( 'speed of motor )( chan-in-

"ext + 'the pase )etween C$%C& plses

"ext " 'repeat this 100 times

/nd If

P1.3 = 0 'set motor direction to CC

o 'repeat followin- rotine

P1.# = 0

ela(

ela(

P1.# = 1

!or + = 0 To ,

ela(

"ext +

$oop ntil P3.5 = 0 'ntil the switch is pressed

The same happens for * and + a!es too. hen initiali-ation is done, the &CGsends message to $C that it#s ready.

Print 2ead(

After that it waits for computer commands. "t#s interested in coordinates and

command which tells it what to do. The computer ass &CG if it#s readybefore starting the job. "f he doesn#t get any reply from machine he warnsas with error dialog. "f the &CG is ready, then computer sends him the first

coordinate with a command what to do when it gets there. hen the driller

is in position, it can do the followingE



• decrease the driller on position mared with HaH in settings and switch

it on,

• mae a hole, that means go down for HbH and then go up for HbH too,

• lift it up to the certain coordinate or

• initiali-e it (send it to top) and switch it off

@ery time when operation is successfully done, &CG sends computer a

message.

Print one

hen $C receies the reply from &CG it sends him ne!t coordinate, if

necessary. &CG receies coordinate with following routineE

Pom1 = ait*e( 'reads 5 4aria)les

Pom# = ait*e( 'from serial port

Pom3 = ait*e(

Pom = ait*e(

Pom5 = ait*e(

"m = Chr6pom17 'con4erts from character to 89CII

Pom1 = :al6nm7 'con4erts from 89CII to inte-er

Temp = Pom1 ; 10000 'mltipl( with 10000

"m = Chr6pom#7 'a-ain con4ert char

Pom# = :al6nm7 'to inte-er

Pom# = Pom# ; 1000 'and mltipl( it with 1000 and

Temp = Temp < Pom# 'add it to pre4ios temp 4aria)le

"m = Chr6pom37 'do the same for

Pom3 = :al6nm7 'hndreds

Pom3 = Pom3 ; 100

Temp = Temp < Pom3

"m = Chr6pom7 'tens

Pom = :al6nm7

Pom = Pom ; 10

Temp = Temp < Pom

"m = Chr6pom57 'and ones

Pom5 = :al6nm7

Temp = Temp < Pom5



= Temp 'at the end assi-n this 4aria)le to

The computer sends absolute coordinates to computer. The &CG then

calculates relatie coordinates (number of motor steps).

Cl*x = s 'he calclates nr. of steps from old

4ale

s = 'and sa4es 4ale of new coordinate

If Cl*x > 0 Then 'assi-n motor direction

irx = 1

/nd If

If Cl*x ? 0 Then

irx = 0

/nd If

Cl*x = 8)s6cl*x7 'calclate a)solte nm)er of steps

Then it moes on desired position.

o

If Cl*x > 0 Then 'if nm)er of steps is -reater then 0

P1.@ = 0 '-enerate cloc*

ecr Cl*x 'and s)tract one

/nd If

If Cl*( > 0 Then 'repeat the same

P1. = 0 'for A axes

ecr Cl*(

/nd If

ela( 'wait a moment

P1.@ = 1 'end cloc* plses

P1. = 1

!or " = 0 To , '-enerate a dela(

ela( 'which determines

"ext " 'motor speed

If Cl*x = 0 Then 'when nr. of steps on axes is eBal

to 0

If Cl*( = 0 Then 'and nr. of steps on A axes also eBal

to 0

/xit o 'end loop

/nd If

/nd If



loop

Print one

That#s all about main routines. 'ome of them are repeated seeral times,

but " e!plained only the main e!amples.

'++)"B(N1 TH) PCB

"f you are going to mae the $C% at home, you will encounter a problem,

because it#s double sided with lots of ias. " suppose that best way to maea professional $C% is to hae it done by $C% manufacturer. The plans for pcb

and all other stuff you can get at the end of this document.

hen you hae your $C% done, you can start soldering '&D components. All

311n capacitors are filter capacitors for power supply. "f you don#t hae 311nyou can use greater alues as well. They should be dimensioned for 21>DC

and preferred si-e is 301.



'&D components layout (bottom side)

Then follows soldering of HnormalH wired components. First solder the lowest

components and then proceed to higher ones. $lease, use socets for D"?chips. The diodes must be 0A6311> fast recoery. F@0% can be used from

Diotec.

"Cs ?0/N must be cooled properly. they should be attached on heat sin"T5 "N'G?AT"7N %@T@@N 5@AT '"NI AND "C'. T5@ T5@8&7

C7NDGCT">@ $A'T@ &G'T %@ G'@DJ

$ower supply connections are made with screw type connectors assembled

from three pieces (9<9<0 pins). As motor connectors " used 'peedy 31 pinsconnectors with flat cables and two wires for one connection. That means

that pins are used for : wires. The last two are used for end switch. (pin /



= hot, pin 31 = KND) %e sure not to short circuit the motor cables. Thecurrent regulator cannot limit current fast enough, since short circuit means

only a little inductance.

Components layout (top side of $C%)

H!- T! C!NN)CT ' +T)PP)0 "!T!02



As we now, there are two basic groups of stepper motors, looing frompoint of coil connections. Gnipolar motor has four coils (or two coils with

center connection, if you wish) and wires on outside. 'ome of them haecenter of coils connected together and hae only 2 wires on the outside.

%ipolar stepper motors hae only two coils and four wires on outside.

Considering that our circuit is intended for driing bipolar motors we willhae no problem connecting bipolar motor to our circuit. "f we want to

connect a unipolar motor then things get a little different.

'ince unipolar motor has center connection on each coil, we can leae this

connection free (NC) and, as you se on schematics of motor, by doing so, we

transformed this motor to bipolar. 7nly problem is coil resistance, so weshould choose this option when coil resistance is low and motor is made for

low oltages (9 to 2>). "f it is too high, the current won#t reach it#s nominalleel and the torue will be lost (>ariant 3). "n this case we can disassemble

motor and brae connection on middle terminal and then connect coils

parallel, as it#s isible on picture, ariant 9. "f you don#t need motor#s fulltorue, you can connect it on one of the side wires and on center wire, as

you can see on ariant 0. &aybe someone will as why don#t we just connectthe side wires together and we would get lower resistance for ariant 9

without disassembling the motor. %ut this won#t wor, since the coils arewinded bifilar and magnetic flu! would be compensated.

"&$78TANTJ

• hen disassembling motor N@>@8 pull the rotor out of statorJ This

way you will partially demagneti-e the permanent magnet in rotor and

motor will no longer hae specified torue.

• "ncreasing current oer specified point, when the magnetic core is

saturated, no longer increases torue but only thermal losses in motor,

resulting in motor#s oerheating and damage.



>ariants of motor connection

e#ll achiee best results with motors designed for : to 31> and for currentsbetween 1.0 and 3.2A.

*0+T +T'0T4P 'N/ C'(B0'T!N

Don#t try to power on the machine without a cooler on output stage "C4s

since they cam be burned ery uicly (" should now, unfortunately). Thetrimmer potentiometers must be in final CC position. +ou can connect

motors for testing right on your destop. The end switches you can simulatewith some eys or switches. %e sure you assembled all as described and asseen on component layout pictures. "f you checed it all twice, you can

power on your circuit and slowly turn the T$9 ( a!is trim pot) in Cdirection. The motor will start turning. &aybe at certain current, specially

when full step is selected, the motor will start behaing strange. This is due

to motor#s resonance, because it is not loaded. This phenomena will



disappear when motor will hae a load to carry around. hen you press onthat mtor#s end switch then the * motor will start turning (after current

adjusting procedure). $ress on it#s end switch as well and then repeat all thisfor + a!is motor. hen all of this is done and if $C% is connected with your

computer, you can start @asy NC drill program, described below, open file for

drilling and press 'tart. The motors will start turning as they will later, whenthey will be fastened in their position. "f any of motors has wrong direction,

just swap the two wires of one of the coils. "f the motors get hot, reduce thecurrent.

"f all of this wors for you, you are really on a good way to mae the final

product woring. Congratulations.

Assembled $C% prototype

+!*T-'0)

The software for controlling of our machine is written for &' indows�

operating system. " tried to implement as many functions as possible, tow "

now that many things can be done better. Any ideas and suggestions are

welcome.



The recommended hardware configuration isE

• $311

• 3&% of 8A&

• 3&% of hard dis space

• '>KA color monitor (11L11)

• 3 free serial (8'090) port

• indows� /2

The program easy to use and " hope ery intuitie too, but "#ll e!plain somedetails any way.



The program @asy NC Drill reads standard drilling files (L.NCD) generated byarious $C% designing programs, but there are some settings to be carefully

set in order to mae file readable by @asy NC Drill. These settings areE

GnitsE "nches

CodeE A'C"" None

ero 'uppressionE Trailing

The CAD program will this way generate a file that will be understandable by@asy NC Drill. " made an e!ample of file which has only one tool and three



holes. 7n the beginning of file there must be line with te!t &: or &;0,otherwise the file will be considered of wrong format.

"$6

NCH,(7

T8$*88+88C8.898

:

T8$

5;88<=;88$

=;88<

5;889=;889

T88

"98

@asy NC Drill supports up to eight different tools and 3111 holes of each

one. hen you open the file, the coordinates are isible in table on the leftside of screen.

hen you hae a file opened and all settings set you can start drilling. &any

of settings are those, which are set only once for your machine and othersmay be set seeral times. The settings are aailable by clicing on button,

ia menu or shortcut eys. 'o, lets tae a loo of these settingsE

arningJ 'ome names of settings may be changed in the future.

Communication



Gnder Communication tab you can choose a port that your machine isconnected to. "f you don#t now which one is it, you can clic on the Find

button and machine will be detected automatically. There are no othercommunication settings necessary since they are controlled internally.

+teps Per nch +P%

"n these fields you can type how many steps does your machine hae to doto HtraelH 3 inch (02,:mm). +ou can come to that numbers by trying. +ou

can draw a $C% with four holes and then drill it with machine and adjustparameters. The numbers are usually around 011 and :11 when stepper

motor with belt directly on it#s a!es is used. "f you use same motors for *

and + a!es, the numbers should be the same.



0ange

"n these fields you should enter the full range of your machine. This dependson it#s construction and is defined in mils. These numbers you get by

measuring of machine range with ruler and subtracting about 0 mm of it. "fyou enter too big numbers, the machine can crash into the end mechanism.

!ffset

7ffset tells us where the 1,1 coordinate should be. "ncreasing offset meansdecreasing our actie area of wor, so consider setting offset to minimum.

Also offset can not be bigger then range anyway. The offset coordinate is

ignored when tool change coordinate is sent.

Trape>oid



The trape-oid distortion occurs, when machine mechanics is not mad enough

precisely (/1�angle between * and + a!es) or when you use laser printer

it#s output can be distorted too. Gsually you don#t notice that. " didn#t toountil " had to drill $C%s made with laser printed film. e can test machine

and printer the same way. Draw a rectangle and print (drill corners of) it.Then measure opposite points. &aybe you#ll be stunned with results. "

measured difference on one @pson laser. "t was almost NumJ The alue canbe positie or negatie.

Tool change

"n these fields we enter coordinate for tool change. This is a position wherethe tool is most easily e!changed. "f enabled, the machine will go to this

coordinate eery time the tool has to be changed.

Head



Gnder mar HaH we enter offset from initial position on top to the $C%#s

copper layer. e should leae 3 to 0 mm for safety reasons, otherwise the

drill can brea if it hits something. Gnder HbH we enter drilling depth. This depends on thicness of our board.

+peed

The speed can be set for * and + a!es together and for a!es. The number

we enter tells the micro controller how many delays he should mae

between motor#s cloc pulses. 5igher alue faster transport. 'peed must be

set in reasonable limits. "f it#s too slow, drilling will tae a while, if too fast,the motors can loose their position on startup and board will be ruined.'peed of motors depends on machine design, motor torue and motor

current. +ou can get your alue with testing.

hen you#re done with setting parameters clic the 7I button and settingswill be saed to program and to hard dis in file cnc.ini. 'ettings are also

saed when you e!it the program.



!ffset again2 nooop%

"n latest ersion of @asy NC Drill " implemented setting of offset when

machine is running. %y clicing the buttons you moe it to certain point and

then hit 7I when you are done. %y default the machine is turned off. "f you

want to turn it on, clic the button &achine 7N and it will go to offsetposition.

" should mention some other settings, which are not aailable from settingswindow. They are aailable only in program#s main window.

-arn for tool change

"f this bo! is checed, the program will warn you eery time the tool shouldbe changed. The drill head will go to coordinates set in Tool change settings

window. The dialog will also tell you which drill diameter is ne!t. "funcheced, the machine will not as anything while drilling and all holes will

be done with the same diameter.

"irror 5



"f this option is checed, the image and drilling path will be mirrored. Thisoption is ery usable, since we design $C%s in Htop iewH mode, but when

we want to drill, we do it from copper side of board, if $C% is single sided.

1o to 8,8 when done

"f this option is checed, the machine will go to 1,1 when the job is done,

otherwise it will go to Tool change position.

7.I. 'o now the tool bar is ne!t. The commands on toolbar are the basic

ones.

!pen NC/

7pens file with e!tension NCD in last used directory if possible. "f file format

isn#t supported or if the coordinates are out of range the error messageappears. "n case that coordinate is out of range it#s possible that we made

our project far from bottom left corner. Gsually the easiest solution is to

moe our $C% in bottom left corner or to put origin point closer to ourproject.

/rill

ell, " guess we#ll need this one. "t starts the machine and e!ecutes selected

job. "f the machine is powered off or if it#s C7& port isn#t properly selectedthe message will warn us, that the machine isn#t responding. Also it will warn

if no job is selected.

+top

$ress stop when you want to end drilling prematurely. A dialog forconfirmation will appear ae .

+ettings

7pens dialog with settings mentioned before.



!ffset

7pens dialog with offset settings mentioned before.

'bout

7pens dialog with some program info and lins to this page.

)?it

Closes program and saes it#s settings.

There are four speed buttons in right upper corner for sending machine tosome often used coordinatesE

TC means tool change position, 7ffset means offset position, 1,1 means

position 1,1 and &A* means ma!imum range position.

'ome of options are not isible until a file is loaded. "n upper left corner ofHdrawing surfaceH the painted circles with chec bo!es, drill diameter and

number of holes are shown when the file loads. The circle paint corresponds

to paint of holes on drawing surface. +ou can select type of holes to bedrilled by checing the appropriate chec bo!.



During the drilling process you can monitor it on screen. Finished holes aremared with red cross and driller path is colored green. e can also trace

progress on two progress bars in status line.

ob in progress

57 T7 &AI@ A &@C5AN"CA? $A8T 7F &AC5"N@

" personally thin, that maing machine#s hardware is the hardest thing todo. The prototype " made isn#t ery neat, but it wors uite well. The main

issue from my point of iew was product#s price. " wanted to mae a

machine that would be ery cheap. " guess in your country, which eer it is,there is a lot of jun computer euipment and that#s ery nice, since we

don#t hae to buy the e!pensie stepper motors.

" will e!plain how " made my machine and where " got my parts. The motorwhich dries machine in * a!es and all mechanics around it was taen out

from an old scanner. The motor should be one with 011 steps per reolution(3,� step angle) and strong enough to moe other mechanical parts



around. +ou can see the motor and Hhome switchH on the picture below.

The mechanism of + a!es is fastened on the arm, which is drien by * a!ismotor.



The smaller motor is driing + a!is on which the driller is fastened. The third

motor, which dries driller on a!is can be connected directly to spiral a!is if it has high enough resolution, otherwise it should hae a gear transmission

lie in my case, where the motor is ;,2�. As you can see the mechanism

which holds the a!is is made from $C% material. "t isn#t ery neat, but it

wors. The only problem is it#s stability which is uite gentle due to weaer

construction. %ut it#s prototype anyway.



The swirly a!is i too out of an older, double speed &itsumi CD487&, the

HguidesH (" don#t now the right word for it but " mean that metal stic onwhich eerything slides.) are ones from old floppy dis units. The motor and

mechanism of * a!es is from old scanner and of + a!es from @pson 'tylus:11 printer. The power supply is also from this printer.



The motor of a!es is from Canon#s typewriter, the flat cables are fromsteering wheel of Fiat#s %rao (Air bag connection). +ou can also use cables

from old dot matri! printers which lead to printing head. All together ismounted on 3 mm wooden board and it is uite fine. The driller is a little

motor with drilling head.

C!"P!N)NT+ (+T

(abel @alue Pcs Comment

83 00 '&D 3 'i-e 301

80, 89, 82, 8, 8,

8/1,:;860 >ertical mounting

8:, 8;, 831 00 '&D 9 'i-e 301

833, 830, 839 318 '&D 9 'i-e 301

83: 4 802 2 '&D 30 'i-e 301

C3 0011u602> 3

C0, C9, C2, C, C,C31, C30, C3:, C32,

C3;, C3/, C01, C00,C0;, C0,

C99 4 C92, C9;4 C9/,

C:3

311n '&D 00

'i-e 301, can be replaced

with greater alues, 001n fore!ample. Not critical.



C: :;u602> 3

C; :u;602> 3

C/ 0,0n '&D 3 'i-e 301 or 112

C33, C3, C03 :;1u6:1> 9

C39, C3, C09 3n '&D 9 'i-e 301 or 112

C0: :;1n '&D 3 'i-e 301

C02, C0 99p '&D 0 'i-e 112

C0/ 4 C90 3u602> :

C9 311u69> 3

C:1 :;u6,9> 3

D3 3N:3: '&D 3

D0 4 D02 F@0% 0: 0A fast recoery

"C3 ?&;?12 3

"C0, "C:, "C ?0/; 9

"C9, "C2, "C; ?0/N 9

"C AT/C0123 3

must be programmed with

propper software. Ket D@&7>@8'"7N

"C/ &A*090 3

D3%*2,

32>611m

3

8@3 '&3430>4: 3 or similar with same footprint

T3 %C09/C 3

can be any other N$N with

hF@ M 011, "cma! 011mAand Gcema! :1>

T$3, T$0, T$9 :;18 9trimmerpotentiometer,

hori-ontal

K83%01C09114

32113 rectifier for 0A6:1>

*3 30&5- 3

$3 0 pin 3"T57GT G&$@8J

Close only for reset.

$0 9 pin 9 'elect half or full step

CN3 "n line

screwdrier

connector, ;

3 Can be assembled with

9<0<0 pin



pin

CN0, CN31 D%/FA 0 Female adapter

CN9, CN:, CN2 'peedy 31 & 9 &ale

CN, CN;, CN 'peedy 31 F 9 Female, for flat cable

CN/ D%/&A 3 &ale

home made cnc drilling machine

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