Latest update
01-03-2010
- SIEG
- a router
- YABS
Why CNC ?
A CNC machine gives the ability to mill curves and contours . As a matter of fact you can join your art to the computer and he translates it in G-codes.
Project 1 The Sieg conversion.
We welcome the Sieg X2.
Description
The Sieg mini mill is sold in Holland as Black & Red . The same machine is sold as Grizzly, Homier, Micromark , Alpha, Bernardo. The Sieg X2 has a little brother X1 and a bigger one the X3 and X3 super
Don't expect a miracle of this mini mill. It is really small with a travel of XY 200 x 100 mm. The stability is sufficient for model makers in light metal. But it has no cast iron mass and milling steel and inox are no proper options.
The spindle is not hardened and the bearings are simple ones. Worth mentioning is the advantage of the MC3 cone in the spindle.
The retrofit of the Sieg
Retrofitting this minimill to CNC
is not that easy, because there is little room for ball screw nuts,
especially in X- axis. A little more space can be made by milling out the
saddle.
Besides, high spending on the issue of ball screws is not proportional to
the basic price of the machine.
So, cheap rolled trapezium thread 16 x 4 mm combined with PETP or POM
nuts were applied.
I. First steps
Backlash in leadscrews is a leading issue. How to get a suitable nut? Machining such small nuts in the conventional lathe is a hard job. The only way is to make a tap.
Trapezium comes in cheap meters and I took 35
centimeters for the tap.
My idea was to make a long cone. The core diameter of 16 x 4 is about 11 mm and from there to 16 mm with
a
top slide angle of about 1 degree, a flow is made from 150 mm. If you want
to copy it, don't use
widia, but HSS cutters at slow speed in taking the fragile spindle off.
After that, 3 flutes were ground with a normal thin disc in the mill. The
cutting edge is 84 degrees.
Believe me, the thing is sharp after finishing with a fine
stone and making a nut in polymer is quite easy. Don't make narrow
flutes, the plactic must go away.
Moving on
Looking forward, I knew that the mini mill has to be sold one day. After this project comes another one with a larger machine. So, all mods must have to be reversible by opportunity to bring the Sieg back to its conventional state. Keeping this in mind, no redundant holes and changes to the original X25 were allowed.
The original X-axis had two thrust bearings separated by a land in the bearing house on the right side. This was maintained including the hand wheel. The stepper motor with a coupler house and a single ball bearing was mounted on the left side.
The Z-axis was placed outside the column and mounted with a single ball bearing on top and a double thrust and ball downside. To avoid wring, the attachment of the nut can be fine-tuned in all directions, by bolts in the angle construction on the milling head.
As to couplers, there is a broad range of alternatives that can be sold and also can be made. My empty pocket urged me to make my own couplers. I copied the characteristic features of Oldham® couplers and redesigned them to "Newham Couplings". For a rapid and accurate production a collet chuck was made. The Sieg got "Big Newhams". Later on I designed "Little Newhams"
The Stepper motors
The slides of the mill will act slightly
when they are running free. At work it will be another thing. There are no
calculations to make for the power of the steppers. So I searched the
internet for experience with the Sieg. Most commonly used are steppers
of 200- 300 oz-in. I took 2Nm bipolar and that is converted 280
oz-inch. Two 1
Nm steppers for X&Y deserved my practice for the first
experience.
Well folks, it won't work. You surely need 280 oz- in.
may 3rd 2005
The Drivers
The well known Thorsten Ostermann www.ostermann-net.de designed 4 Amp drivers and a break out board. I chose these for my 2 Nm steppers, and they are performing quit well. My connection in Holland for these is www.damencnc.nl
Evaluation
Until march 2006, the Sieg
is mainly used as engraving machine.However, the spindle speed of max
2500 rev/min is not sufficient for this purpose. The Sieg will get
another mission. Its accuracy makes it more suitable for milling small
parts in 2,5D.
I enjoyed the first steps with this low budget CNC.
march 18th 2006
____________________________
The magic of 3 phase steppers,
New drivers have been made for the KT60KM06 3 phase steppermotors from Japan Servo. The steppers possess only 3 wires and are three phase with a star coil configuration. Specifications and (dis)advantages will be published here soon. A driver is based on the HA13532 and the bridge SLA6023. A new router has three of these motors and I think that I am the first to get such in hobbycnc land.
These motors are salvaged from copiers. The difference between the commonly
used 2 phase steppers is not quite obvious for my application. The specs of
the manufacturer speak of more torque at higher speed. My statement is
only, that they are working with the
apparant low holding torque of 0,5 Nm and in half step highly accurate with 1200 steps/rev.
The set up of the measurement of the torque and the trial for inductive sensors as shown below.
Z AXIS
X AXIS
Chinese machines are yellow painted
inside 
The Sieg becomes an adult, the color is RAL3003
Engraving
Project 2 A Router 2005
Starting a New Router
This new router was developed in a projectteam. The availability of cheap 3 phase steppers made the engineering of new electronic drivers necessary. That is beyond my comprehension, and in exchange of chip sweeping services, I got the support of a professional on this issue. The knowledge about the software was added by another companion so, I could concentrate on mechanics and draft.
This router was a platform of exercise for all aspects of building and design, managing budget and cooperation between the participants.
First steps
We started thinking of a workspace of about 250 x 300 mm with a Z of 160 mm and possibly more.
Strategic:
Most routers are moving gantry ones and have a fixed table.
However, for the
small workspace in this case a moving table is suitable. So there is a
steady bridge.
First points of departure were creating stability, avoidance of backlash and smooth operation. That lead of itself to the first item : the saddle. It is the most complex thing in the router and a crucial part of the whole. Stability means mass of metal and a competent dimension. And the dimensions of the saddle have consequenses for the rest.
Second was the workspace. What is our goal? Really make it productive or is it a matter of learning? The last thing was most important: the machine should have certain capabilities, but is actually testing area for components. So the workspace was subordinate.
Third, but not at last, the router might not ask big spendings: the whole thing must be made from scrap as available.
This circumstances lead to a process of sequential draft:
-
take a suitable handmill
- fix the Z- axis travel and the altitude of the saddle above the
table, create a imaginary"cube"for the objects to be milled on
the table. Watch the height of vices etcetera, and the length of milling
tools.
- look at the saddle width
- what should be the effective way of Y, and take a little
oversize
- dimensions of the frame of the machine
- determination of the X travel
- length dimension of the frame
- tuning in the table dimensions, think about the clamps, bolts
and stairblocks
After that we put down the sketch pencil, and worked it out behind the monitor
Project 3. The MINIminimill
This project is based on the X1 from Sieg Corporation. The crosstable has 0,5 Nm Japan Servo Nema23 motors.
Project 4 The Lathemasters conversion 2007
Last year I found a crippled lathe in Buitelaars store in Waddinxveen. Only €350.- and no questions. I never never have any questions... I have plans. :))The conversion has started lately. Changing the X/Y-axis is no problem. The main spindle however, should be a step/ direction controlled axis and not only RPM controlled.
March2007: mechanics are done. I have changed to electronics.
Yet Another anti Backlash Solution
Yabs! This concept is very simple and the solution is
acting alike a collet chuck. The 40 mm long POM nuts are
incised over three quarters of their length with 1, 2 or 3 kerfs.
The 2, 3 or 4 members are kept on their free end by an O-ring with an adequate
tension enclosing the thread. Thus a dynamic fill of the trapezium
thread will be
achieved. Several pilots learned, that with the right dimensions of the
screw, nut and O-ring, major forces can be transferred. There are truly
two nuts: a static and a dynamic one. I'm looking for the right
dimensions yet. And a first trial with an pneumatic YABS! is almost
finished. Anyway, the kick is to save
much money on ball screws. They are open source, so go ahead!
The First and only Cross Table
with
in the world.
This is the first attempt to get a full functional mill
at a rock bottom price. Black & Red has upgraded the X1 minimill
with a larger table and the former tables are selling off. The base of
the table has an extension for the column. From there fantasy must take
over.
The first table is equiped with common Nema 23 |Japan Servo's of 0.5 Nm. Two others will get the 3 phase 60 x60 mm Japan Servo's with high resolution 1200 steps/rev in half step. It seems that these motors are more powerfull than expected, anyway they have an 8 mm shaft.
- My friend Joop started with a small cross table, Nema 17 steppers and Linistepper controllers. His zealous mind brought him not only to use Ostermann drivers, but he has now an integrated and for each motordriver seperated supply unit, a standalone unit for VCC 5 volt and a main motor driver. M-codes are now in use. By the way, Joop used YABS!of course.
It looks very nice. It's all in a 19" rack. What should be his next step?
- My friend Rinus took the same table as Joop did, but changed it his own way with Sanyo Nema23 StepSyns. Rinus had only a file, a hacksaw and handtools, but old fashioned excellent craftsmanship. The logic drivers were mount on a universal board and the bridge drivers were taken from a copier print by using a fret saw.
Rinus deserves to be honoured for his patience and staying power.
Old and replacement YABS
YABS in different forms
Joop's CNC
A power unit
3 microstepdrivers 3 amp phase current are in use for 2 mills
