Hossmachine_Cnc Conversion

This mini mill/drill machine has two speed ranges—0 to 1100 RPM and 0 to 2500 RPM—great for different thicknesses and types of material. Features a micro feed that allows the operator to feed at .002'' per line.

Heavy duty cast iron body and base for better stability. Precision machined table. Includes drill chuck & key, shaft and chuck key assembly and wrenches.

    * Motor: 4/5 HP, 120V, single phase
    * Speed ranges: 0-1100 RPM low, 0-2500 RPM high
    * Spindle taper: R8 with JT33 chuck taper
    * Spindle stroke: 8-1/2''
    * JT33 chuck capacity: 7/64'' to 1/2''
    * End mill capacity: 1/2''
    * Face mill capacity: 1''
    * Swing: 12''
    * Depth scale: 0 to 12'' in 1/16'' increments
    * Table slot width: 1/2''
    * Table dimensions: 15-7/8'' x 3-11/16''
    * Height: 33-3/4''
    * Shipping weight: 150 lbs.

To begin, I had to decide on the Stepper motors and Controller.
There are many types to choose from and many companies sell kits in various configurations.
I originally used a 3-Axis driver from Stepperworld.com but the performance was not up to
expectations. I recommend getting drivers from Kelinginc.net. I use the KL-4030 now. It is a single
axis bipolar driver rated up to 40 Volts and 1/64 microstepping. It has over voltage and short
circuit protection built in. You'll need one per axis. Keling also has complete kits with motors,
power supply, drivers and a breakout board. Nema 23, Option C or D with the 425 oz/in motors
is recommended. You can also find some nice power supplies at Circuit Specialist.
The bipolar driver only needs 4 wires so I used some 16 AWG speaker wire.
I get much more speed and torque now. I get up to 130 IPM for the X, 65 IPM for the Y and
40 IPM for the Z Axis. I'm running at 1/2 step for the X and Y axis and full step for the Z axis.
I have a counter balance installed as described here. It turns
out it wasn't necessary as the Z motor has plenty of power now to raise the head without it. I'll
leave it be for now, it should make life a little easier for the motor.

To mount the steppers, I made aluminum mounting brackets. Prints for them are below.
Holes must be drilled and tapped 1/4-20 on the mating surfaces of the mill. The hex
rods (1 3/8in. long for the Z-axis, 2 1/2in. long for the X and Y) are tapped 10-32 for the motors.
The ballscrews must be turned down to match the prints. The ballscrews are case
hardened, but cut easily with a carbide insert.
The ballnut stop blocks replace the original brass feed nuts. The X-Axis requires some
material to be removed from the saddle to give clearance for the nut and stop block.
I just used an angle grinder. The drawing will show where. I found a 15/16-16 tap to
thread the stop blocks at Wholesale Tool. Use a 7/8 drill bit to bore the hole.
The Y-Axis does not require any modification to fit the ballnut and stop block but I'll
include a pic of the mod I made to give some extra travel. I wound up with 8 1/4 inches
of travel on the X-Axis and 4 1/2 on the Y-Axis.

I mounted the Stepper Motors with custom made Aluminum brackets (See Fabrication).

For the Y-Axis, I used Thrust Bearings from Mscdirect.com.
    03548591 3/8 X 11/16 X 9/32 SET THRUST BALL BEARING (2 sets)
The X-Axis uses the stock bearings.
For the Z-Axis, I used thrust bearings and needle flats from Mscdirect.com.
    03380961 1.250X1.938X0.078 THRUST CAGE-NEEDLE ASSEMB
    03381142 1.250X1.937X0.032 THRUST WASHER-NEEDLE-FLAT (2)
    03380045 1.250X2.344X0.625 THRUST-BALL-BANDED MEDIUM
and Metal timing Pulleys and belt from Stock Drive Products and Sterling Instrument.
    A 6A 3-16DF03708 .200 (XL) Pitch, 16 Teeth, Aluminum Alloy Timing Pulley
    A 6A 3-32DF03712 .200 (XL) Pitch, 32 Teeth, Aluminum Alloy Timing Pulley
    A 6B 3-060037 .200" (XL) Pitch, 60 Teeth, 3/8" Wide, Urethane Belt

I converted the feedscrews to Ballscrews from Homeshopcnc.com but they have
switched to precision screws and the new nut will not work with my plans.
Another source for the ballscrews and nuts and a little cheaper is Roton.com.
They use square nuts and the X axis nut will need the corners ground off a bit to fit.
Grainger.com also carries the Thomson precision rolled Ballscrews and round Ballnuts that will work.
This increases the accuracy and lessens the backlash.
Also, the original feedscrews have a pitch of .0625 ( 1 turn of the crank= .0625in. travel)
while the ballscrews have a .200 pitch (1 crank =.200in.)
The steppers have a max rpm of 120 RPM and 200 pulses per Rev.
This means the table can rapid 8 in. in 20 sec. with the ballscrews
instead of 1.07 min. with the feedscrews. As a bonus, one step pulse
of the motor = .001 in. travel. That makes programming easier.

ballscrews

ballnut stopblocks rev c

cnc z axis mount overview

cnc z axis mount top and bottom rev b

stepper crank handle

stepper motor couplings rev b

x axis stepper mount

y axis spacer

y axis stepper mount

z axis ballscrew base mount rev b

z axis ballscrew mount

z axis ballscrew mount rev b

z axis inner block

z axis spacer

z axis stepper mount

z axis stepper mount support left side

z axis stepper mount support right side

z axis stepper mount support right side placement

x axis ballnut clearance

x2cnc table travel increase 1

x2cnc table travel increase 2

x2cnc table travel increase 3

x2cnc table travel increase 4

x2cnc table travel increase 5

Next attach the ballscrews to the brackets and adjust the (2) 3/8-24 jam nuts to give as little
backlash as possible. Thread the ballnuts into the ballnut stopblocks. Position these into
slots in the saddle. Feed the ballscrew assemblies into the ballnut assemblies and mount
the brackets to the mill. Slide on the Stepper Couplings and mount the Stepper motors to
the 2-1/2 in long hex rods with 10-32 screws and snug the coupling allen screws.

The Z-Axis assembly begins with removing the plastic cover on top of the column.
Drill 4 holes to mount the Steel Z-Axis Inner Block about 1/16 in. below the top of
the column. Follow the instructions in the "Z Axis Breakdown" for the assembly of the
other parts. Feed the ballscrew into the ballnut and attach the Z-Axis Ballscrew Base
Mount. Once all is mounted on the mill, mark hole locations for the ballscrew base
mount and drill and tap (2)1/4-20.My spindle casting was not square so I added a .045 shim
on one side so that the ballscrew does not bind up. It will travel up till the mount touches the
bearings. I get 9.8 inches of Z Axis travel.Mount the Stepper Motor to the 1-3/8 in. long hex rods
with 10-32 screws and adjust tension on the Timing Belt. Mount the Stepper Crank Handles.

Z-Axis Assembly 1

Z-Axis Assembly 1 closeup

Z-Axis Assembly 2

Z-Axis Assembly 2 closeup

Z-Axis Assembly 3

Z-Axis Assembly 3 closeup

z axis ballscrew base mount

Z-Axis Stepper

X-Axis Stepper

Y-Axis Stepper

z axis breakdown

z axis breakdown colorcoded

z axis ballscrew mount shim

z axis travel limit top

z axis travel limit bottom

Build the Controller following the instructions from Xylotex. I used an old PC
case I had lying around but it doesn't need that much room. Any case about 7x7x10
would work. You could buy one at one of these companies. Or search Pricewatch.com.
The Computer to run the software doesn't have to be very powerful. I use a 1Ghz CPU
with 256 Megs Ram, 20 Gig Hard Drive and Windows XP. A used Laptop would work.
Careful with some of the newer systems that don't have a Printer port because the
Controller needs one to communicate with the PC. USB ports will also be needed later
for one of my other projects.

Now is the fun part, getting the mill to make something.
Stepperworld includes a cd with some software to run the motors. A basic program of their
own for jogging and running the motors is good for testing whether you wired the steppers
correctly. They also include a demo of Kcam by Kellyware. They also include a tutorial that
shows how to configure the printer port. This is OK for practicing but for really getting all that
the mill can do, I prefer Mach3 by Artsoft. You can get a free demo that will run a gcode
program up to 1000 lines of code. (Many engraving programs will exceed this limit as you'll
see in the following samples. Most milling operations will fall under this limit).
Links to the software I mention can be found Here.

mach3 ports and pins motor outputs

mach3 ports and pins input signals

motor tuning X Axis

motor tuning Y Axis

motor tuning Z Axis

24 Car engraving tutorial 1

24 Car engraving tutorial 2

24 Car engraving tutorial 3

24 Car engraving tutorial 4

24 Car engraving tutorial 5

control panel 1

control panel 2

control panel 3

control panel 4

engraver bracket progress 1

engraver bracket progress 2

engraver bracket progress 3

UPDATE: For extra support for the Z axis stepper mount, I drew up new prints above.
Use these 2 brackets to attach the stepper mount to the column using 1/4-20 bolts.
This will give more strength an eliminate the need for the Z Axis Inner Block and Spacer.
To machine the bearing pocket in the Z Axis Ballscrew Mount, you can use either a large lathe,
a boring head, a rotary table or complete the X and Y axis CNC conversion, then use the mill with
Mach 3's Circular Pocket Wizard and lower the Z Axis by hand for each pass.
Each method has been used successfully by others.