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You Have Found The MOST COMPLETE,, SOME WOULD SAY
ULTIMATE, CNC SETUP PAGE !!!
A "110% What I looked for as a Beginner but NEVER found" page.
As a beginner I searched for weeks trying to find a full setup to either copy or figure out what was
needed to start. I have laid out my steps, with links, and hope it will help you while putting together
your "perfect" machine. My mill generally rapids at 22-30"/min. Accuracy is beyond .001 mm. Enjoy!
Updated 2011: So much has changed since I first made this page and thank everyone for the great feedback I have received over the many years. Some of the items listed are discontinued, updated, now easier to find than ever, etc. However there is still a lot to learn regarding a good CNC Setup... So enjoy!
• Mechanical Setup • Driver Setup • Driver-Power Supply Enclosure • Machine Enclosure
~ For Software Setup please Click Here
STEPPER MOTOR MOUNTS
I bought the Sherline stepper motor mounts and while a little more expensive then others, they are WELL worth it! They are for frame size NEMA 23 motors. They come with a wonderful coupler making the "perfect" setup a little easier. Spend the extra money and go for a better setup now. It will save you in headaches and disappointments later. 1-01-02
TRIED MAXNC UNIPOLAR MOTORS
My brother had some MaxNC 70 oz unipolar motors so I tried them. They are not strong enough to move the Sherline with authority, especially the Z-axis. While they're suitable for other applications, this is not one of them.
Repeat: 70 oz/in motors (or any around this range) are not strong enough to run the Sherline mill. Do not buy them for this application. From what I understand, bipolar steppers are a better choice due to lower heat output and power/speed ratio. If possible, servo motors are even a better choice.
I bought NEMA 23 Sanyo Denki 180 oz/in BIPOLAR double-shaft STEPPERS. I attached the hand wheels on the opposite side and find this to be a huge advantage. I suggest buying bipolar double shaft motors so you can adjust the axis or perform mild milling manually as needed (plus the wheels look cool spinning around :). The number is 232-180-DB from the link below. The motors came on time and were packed with great care, thanks! They are PERFECT for the Sherline. Don't forget to balance the handles if you do plan to mount them. Note: A combination of motors, 180 oz/in on the Z axis and around 100-180 oz/in on the XY would also work. Here is the link: CNC Retro Links
Want to learn more, Click HERE
As I learn more, servo motors are even a better choice with their drivers, they are however more expensive. Gecko 201 drivers seem very nice, check them out. SERVO motors usually have a "closed feedback system" so if the motor stalls or "loses steps" it feeds back to the computer to let it know. The software then compensates for the lost steps in hopes that the part will still be made correctly. ** This, however, is not a reality in our hobby cnc yet that I know of.** Servo motor cannot be stalled or they will burn out quickly, Basically a servo motor is a DC motor with an encoder. Very neat.
A STEPPER motor system (mine) which is "open-loop," my software has no idea where my motor is at any given time. If one stalls the steps to the motor keep going as the computer thinks nothing is wrong (no feedback). You can add a feedback to steppers if you like but then, you might as well get the better setup- servos. HOWEVER, I can say a 180 oz motors geared down with the leadscrew on my Sherline makes for a VERY strong system. It will snap a 1/8" endmill and larger in a blink! It will also crush a finger (don't ask me how I know this :) Personally I don't think I have had problems with losing steps but again if you can afford
Psst: I have servos now :) Click here
Overall impression? Steppers are a but louder, run a bit hotter, but can be stalled all day and do the job just as good as a servo motor. I don't see much of an advantage in getting servos over steppers. They both run, they both work.
-CHECK AXIS AND LEADSCREW FOR "PARALLEL-NESS"-
While tightening down your stepper motor mounts, check to see if the TIP of the leadscrew deflects. If so, your mount is not parallel to the axis and you will find binding in the system. First try to reposition the motor or the mount to minimize this deflection. If that does not work, file, add shim, do what you need to make the movement minimal. Check to make sure you have smooth movement throughout the axis.
I had to file my Y axis base vertically to make the mount fit parallel. I also added a shim (broken piece of single edge razor blade) under the motor mount on the Z axis to make the leadscrew runs parallel to the axis. Check this now.
GRIND FLATS unless you plan to never remove your motors :)
File or grind some flats on the stepper motor shafts where the set screws will tighten. DON'T omit this very important step or you may not be able to get your motor off without excessive force and damaging your motor or mill.
NEW Y-AXIS MOUNT
My Y-Axis, stepper mount holes stripped and I tried a few things to fix it. It finally dawned on me to make a plate with fresh tapped holes for the stepper motor mount (sometimes I forget I have these machines:). It added 6.5mm of travel to the Y axis.
I had to figure out a way to get the backlash out of the Z axis. For details on this setup
I lightened my mill by cutting off the larger pulley and removing the control box. Not only is it LIGHTER the work is MUCH easier to see. If you do any "real" modification, I would suggest this one- get rid of the control box from the mill! I added a red 110 volt light to tell me when the mill is on and another to tell me when the spindle is on (bright yellow LED). Click HERE for my 110 volt modification.
The control box is now mounted to the back of the Sherline. I also made a larger motor pulley and made my mill's pulley smaller to increase rpm. A lot of work but well worth it!
Make sure your comfortable working with wires and soldering before you attempt this modification! Don't go ruining your perfectly working mill.
I added some springs to aid in pulling the Z-axis up (bought from the local hardware store). I made simple mounts which are mounted to the stepper motors existing holes and put the springs on them. At the bottom I just drilled and tapped for some 10-32 screws. Even when the Z axes moves down there is some "backlash" amount that it may get pulled further down by the endmill (think about it). My design is to try to keep this from happening and to aid the stepper. Others say this is not a good way to do things and to have the springs pulling the Z axis down into the work which aids in trying to get that backlash out in the first place.
I bought a cheap 12V 20 watt halogen light from Target. I used some of the parts and made a new light which is attached to the mill. The power for the light is a small track lighting unit bought from the local hardware store and is also mounted on the back. Its 12V 35 watts, It gets a little hot but the light is bright, white, and sharp.
Balance those wheels for CNC use or the mill will shake like an out of balance wheel. Make sure to get “double sided motors” so you can sill use the wheels (and they look cool spinning).
Next: Driver Setup and Enclosure
I eventually wanted more speed out of my spindle. I cut the output pulley smaller on my lathe and made a new larger pulley for the motor. I am using an “O” ring as a belt and am happy with the results. While the speed is faster it is also a bit weaker.
IT BEGINS! 04-25-00
It all started off with a manual Sherline Milling Machine. All Sherline products I have bought have been very well built, delivered on time with excellent customer service!
The endmill should move TO THE PART.
+X Head move to the RIGHT So the table moves to the LEFT.
- X Head move to the LEFT So the table moves to the RIGHT.
+Y Head moves BACK So the table move TOWARDS you.
- Y Head moves FORWARD So the table move AWAY from you.
+Z Head move UP
- Z Head moves DOWN.
WHAT’S UP WITH THOSE Y-AXIS UNITS
The laser unit engravings on the Y axis of the machine are backwards! This issue has been addressed but I don't know if it has been changed. Disregard them. I put a piece of "trim sheet" (black vinyl sticky covering) over my axis to cover them up. I hated to do this but they kept messing me up.
Note: You can get much cheaper rex step 260 oz steppers for $40!! HomeShopCNC I bought the rest of the stuff from MPJA Supply. Good service and good prices! Also, you can pick up cheaper surplus motors, just do a search. Here are some places, American Supply and Surplus, Ebay, All Electronics, My Links...etc