|Frequently Asked Questions|
Q: Does the software support G & M codes?
A: Yes, most of them. Refer to the G&M Code Guide to see which ones are supported.
Q: What is the difference between MyT'Mill and EasyCAM Pro software?
A: The differences are listed in this comparison table. I plan to continue increasing development and price of EasyCAM Pro while MyT'Mill will stay as the low-end product without much additional improvement.
Q: Are the motors double-shafted, so I could use my handwheels too?
A: Yes, all motors have double-ended shafts so you can put the handwheels on the back of the motors.
Q: How does your software and hardware work together to get motion? Why do some systems have a separate hardware controller?
A: Typically a computer software program (CAM) reads G-code and sends instructions to motion control hardware. The motion control hardware interprets the instructions and sends pulses to the motors in the right sequence. Motion control hardware usually consists of two pieces, a controller and a driver. Some systems have controllers and drivers built onto the same circuit board. Other systems sell and package them separately.
The controller is the low-power intelligent part. It figures out how many steps are needed to move from point A to point B and in which direction. This is pretty easy if you have just one motor travelling at a constant speed. Things get much more complicated when you have coordinated motion in two, three, or four motors at the same time like when you move in a circle or spiral. Then throw in ramping where you are changing speed at the same time you are doing coordinated motion! The calculations can get real complex.
The driver hardware takes the low-power step and direction signals from the controller and converts them to high-power voltage pulses to the step or servo motor. A 4-lead step motor has two separate coils of wire. An 8 lead step motor has 4 separate coils which are connected in series or parallel to make effectively two separate coils. The driver hardware takes step and direction signals from the controller and energizes the two motor coils in just the right way to make them move a set distance, usually 1.8 degree per step or 0.9 degree/step if the hardware is using "half-step" mode. Some more expensive drivers are capable of even finer degrees through a technique called "micro-stepping".
Our Standard and Pro motion control hardware boxes are really just Drivers. The complex controller signals are calculated by software, not hardware. The signals are sent to the drivers using the parallel printer port. The primary advantage of this technique is cost and simplicity. You eliminate the need for additional controller hardware. The disadvantage is speed and smoothness. Since Windows is doing other things in the background like checking for buttons being pushed and keeping track of mouse movements, you may notice a "chirp" now and then in the motors if the cpu gets over-taxed causing timing signals to become less consistant. As computers become ever faster, this effect becomes less noticable. It's really not an issue at all for the slow machining speeds used by small desktop milling machines and lathes.
Q: Will the software work with my brand X controller?
A: 1) The controller box must be controlled from the parallel port of a PC compatible computer via 25 pin connector, running Win 95, 98, or ME.
2) Your controller box must use either step/direction type drivers or direct phase drivers.
3) Step/Direction drivers take two signals and turn them into a 4 phase sequence to the step motor using special hardware. If your controller uses step/dir type drivers, you need to know which pins it uses for each motor. Typically pins 2&3 are step/dir for X, 4&5 for Y, 6&7 for Z, 8&9 for the 4th axis. The software can be set to any combination of these pins.
4) Direct phase drivers merely amplify the signal being sent to four pins in the correct sequence by the software. Since it takes 4 pins per motor and there are only 12 output pins on the parallel port, you are limited to 3 axes for this type of controller. The pinouts in the software are not configurable for this type of controller either. Your hardware must use pins 2-5 for X, 6-9 for Y, and 1,10,14,16 for Z.
5) If you think you meet the above conditions, please download the demo and give it a try before you buy, just to make sure. The demo software actually can drive the hardware.
Q: I have read that Windows-based multi-axis controllers cannot run the parallel port quickly enough or steadily because of all the background things that take up processor time within a Windows environment. This can cause the steppers to miss steps or to not ramp up and down smoothly and accurately. How have you overcome this problem? Also, what processor speed and memory requirements do you have?
A: You are correct that top speeds on most windows programs, including MyT'Mill and EasyCam Pro, are probably less than what you can achieve with Dos programs due to the added Windows overhead. "Quickly enough", however, depends largely on your application. The real limit for your application may be something else like the speed the bit will break or the control driver/step motor combination speed limit. I see significantly different top speeds depending on which stepper motors I use. Basically low inductance motors will give you more speed but less torque. The speed can also be increased by using higher voltage drivers, so it's impossible to say exactly how your system will perform. The best thing to do is to download the demo and try it out. There is a "speed test" feature which can quickly show you what your system can deliver.
Any PC running Windows 95, 98, or ME will work directly. You don't need much RAM since the steps are sent on the fly and long programs are buffered to disk. Performance (speed and smoothness) will improve with processor speed. My system uses a 600mhz Athlon CPU. I see top speeds of 19 in/min using 2mH, 140 oz-in motors and 11 in/min using 8.4mH, 250 oz-in motors. These speeds are on a Sherline machine (which has 20 tpi drive screws) and using AMP 2035 drivers at 24VDC. The speeds are from a dead stop without any steps being lost so no ramping is needed. The real limit on these small machines with small cutters is when the bit will break, maybe 2 or 3 in/min. You can turn ramping on in the software but it's really only good for long straight
lines, like if your were using it to roll a heavy barrel or position a heavy bin.
Q: I get a "Priviliged Instruction" error when I run the software on WinNT/2000/XP. What's up?
A: WinNT, 2000, and XP have security protocols which prevent directly accessing the parallel port like you can with Win98 and below. However, you can unlock
the security for specific programs and ports using third party applications. One that I use is called Direct-IO, available at www.direct-io.com. It costs $29 but there
is a free demo that works for a month to try it out. After installing it:
1) Open Control Panel under Start Menu/Settings. Double click DirectIO. Click the I/O Ports tab. Enter 378 in the Begin field, and 37F in the End field then click
the Add button.
2) Click the Security tab. Enter the directory\name of the program, eg.C:\Program Files\EasyCAM Pro\EasyCAMpro.exe or c:\mytmill\mytmill.exe. Then click the Add button.
3) Run the mytmill.exe or EasyCAMpro.exe normally.
I have not used it but one of my users tells me there is another program (free) called "userport" that works just like DirectIO. It comes as a zip file; one must register the userport.sys (or just stick it in the c:\windows\system32\drivers folder), and then run the executable to configure it in a similar way to directIO.
Q: Will the software support motion greater than 4" x 8" x 6" if I use my own positioning hardware?
A: Yes. There is no size limit in the software.
Q: What if my application uses a different thread pitch? Won't that affect the distance moved?
A: The software allows you to change the motor resolution to match your drive screw.
Q: What is involved in the conversion from manual Sherline machine to cnc?
A: The conversion takes less than an hour and uses existing holes in the machine. There is no drilling or machining of any kind.
Q: Can the software do 3D parts for molds, etc.?
A:There are several options for what to do with the Z coordinate when importing the DXF file. You can specify a default depth of cut value to use for all tool paths, you can set a depth for up to 6 different line colors, or you can use the actual Z coordinate in the DXF file if it was written from a 3D CAD package. The display algorithm assumes a 2D part, however. If Z is negative, it assumes cutting is occuring and draws a thick solid line. If positive, it assumes the tool is moving to the next tool path and the line is thin dotted. The real tool, however, is actually traveling to the 3D coordinates specified so if you have lines that are shaving down the part in 3D, it will do it. Don't expect to give it the DXF file of a finished 3D part and think it's smart enough to know how to shave a block down to that shape. There are very expensive CAM packages out there that will do that.
Q: I am planning to CNC-ize my Sherline lathe and am looking at your products. From your web site it seems like the CNC lathe conversion is exactly the same as the mill. I am having a hard time conceptualizing that. I can understand the same hardware would
work, but would think that software and maybe some controller firmware would be needed. While I know this can be done and it is still just "x and y" movements, it seems to me that the type of cuts made in turning a part are considerably different than milling a part and that the software (e.g., the algorithm which plans the cuts and optimizes the tool path) would be different for a lathe than a mill. Can you enlighten me?
A: Regarding lathe software. For MyT'Mill, it's the same for both mill and lathe. Basically you draw the tool path in CAD and MyT'Mill will follow it. So imagine the final shape of a spindle and take half of that. You draw that shape in CAD, then use the CAD's offset command to offset that shape many times by the depth of each cut. Then overlay a rectangle representing the rough material and trim away all the lines outside the block. Then connect all the ends so you have one continuous maze-like path. Then you write the DXF and import to MyT'Mill. Then set the home position to the lower left or right nearest outer open end of the path. Then use the optimize path command to connect it all into one continuous sequence of G-code.
EasyCAM Pro does all that automatically using a G71 command. All you have to do is draw the final shape and it figures out how to whittle away the cylinder.
Q: If the same package works, does that mean I do not need a separate controller and software and only need to purchase mounts, stepper motors and connections?
A: Yes, the same controller and motors can run either the lathe or mill. Many people just buy a couple extra motors and mounts for their lathe.
Q: I'm looking to use your software to control other stepper drivers rather than the one's offered by Acumotion, Inc.. I understand MyT'Mill for Windows works with the parallel port, and controls up to 4 standard Step/Direction drivers simultaneously with configurable pin-outs. Can you describe the pins used by the software and what kind of signals should be expected/delivered?
A: The software can control 4 step/dir drivers simultaneously using pins 2-9. Typically X=2/6, Y=3/7, Z=4/8, A=5/9 but you can set them to whatever arrangement your hardware requires. The step signal is a square wave with 0 volts for low and high is your printer output voltage, either 5VDC or some newer ones use 3.5VDC. One customer told me he measured the pulse rate as high as 50000 steps/sec. Direction signal is either low (0) or high. Polarity is reversible in the software.
Q: Saw your software and was most impressed. Problem I already have a TAIG with a MicroMill 200HD driver using MAXNC DLX software. Question would your software run this four axis driver?
A: We recently added support for a 4th axis. If your driver has step/dir type inputs it should work. Download the demo and try it out. The demo will actually drive it.
Q: I turn pens, pencils and such for a hobby. I have been considering purchasing one of your CNC mills for engraving and machining the pieces for cases, boxes, etc. for my crafts. Do you think that there would be a way to slightly modify a mill to operate like a lathe or to at least turn out a cylinder. Say swap a couple of the stepper motors to change the axis?
A: The software is the same for the mill or the lathe. In either case, the cutter simply follows the path you draw in the CAD software. Some people who want both mill and lathe operations for minimal price buy the 24" lathe and add the vertical milling column accessory.
Q: What is the main difference between the unipolar and bipolar drivers?
A: More speed with the bipolar units and the torque doesn't drop off quite as fast with speed.
Q: Can I cut threads (interior and exterior) with it ? or will I need to buy some other accesories?
A: No, not on the sherline. The sherline has a variable speed spindle. You need to coordinate the spindle speed with the feed speed for threads. They have a thread cutting attachment that does this but it's not CNC adaptable.
Q: Can the drivers be set up in metric co-ordinates ?
A: Yes, cm or mm.
Q: Does your software have memory or vector limitations (the ability to accept files of 640 k at a time for example, therefore necessitating files to be spooled incrementally)
A: No limitations on size, only the RAM on your machine. Some customers have run 10000 line programs.
Q: Does your company only specialize in the stepper motors, drivers, and NC software?
A: Yes, thats all we do.
Q: Do you have modular upgrades with respect to 2, 2.5, 3 and four axis capability?
A: No, the same software does it all for one low price
Q: Does your system require a dedicated PC per CNC machine or can the machines be networked.
A: Needs a dedicated PC
Q: How do I take care of enabling a post processor in the event of having to use generic CAM software?
A: MyT'Mill uses regular text files so it should be able to run 3rd party Gcode, provided the codes are supported. A list of supported codes is shown on the web site under Customer Support
Q: Do you have backlash compensation on your software? Can it be recalibrated if necessary?
A: Yes, the backlash compensation can be set in units of 0.0001 and can be reset anytime
Q: Is it necessary to install limit switches or is this a function that can be installed in the software?
A: Limit switches are not supported.
Q: Do you have a system for periodically checking the accuracy of the machine and then recalibration?
A: No, but there is a "Speed Test" mode which will go back and forth at various speeds. The cutter should end up where it started if everything is OK.
Q: We own an Emco compact 8 lathe. Are you aware of this make and model and is it possible to install a retrofitted CNC system onto the existing hardware as with the sherline?
A: I tried to get MyT'Mill to work with an Emco lathe once. Don't know if it was an Emco compact 8 model. Emco did some funny things in the electronic hardware so that it took more than just a step and direction signal to make it work. They have some kind of security built in so everyone has to buy their software.
Q: I am interested in one of your mills, part #2000 (inches). 1) does this have a 14In base? 2) what are the axis travels?
A: The 2000 has a 14" base to accommodate the pivoting mechanisms and to take advantage of the increased swing movements. But the travel remains the same as the 5400. The travel quoted on the web site is for CNC version which eats a little travel. The manual version is 9" x 5" x 6.5" (X,Y,Z). There is a Horizontal Milling Conversion which allows larger work pieces to be machined but it doesn't increase the travel. You'll have to call sherline to see whether that accessory works for the 2000 mill though.
Q: I will need XYZ axis . Can the motor of X axis be stepped up to a 450 oz/in size and still operate in the confines of your controller ?
A: Yes. The controllers are limited to 2 amps/axis though. 450 oz-in motors use more than that so they will not operate at their full capacity. The economy controller 10011 has other limitations as well.
Q: I have been looking at a lot of setups lately and yours seems to be complete. Will I have problems with a high frequency start on my plasma machine, are your cables resistant to it in regards to computer link ?
A: The motor cables are shielded, but I don't know about the computer cable.
Q: I am interested in the 10011 kit to start with. would your MyTMill software be compatible for plasma cutting ?
A: I have one customer using it for plasma cutting. He purchased the Pro controller for faster speed and then used several belts and gears to reach the speed he needed. He uses the 4th axis to turn the torch on and off. He is very happy with the results.
Q: If I was to purchase a unit what travel per revolution would i get , I want to set X/Y axis up on toothed belt drives, how many teeth would the drive pulleys need , or is this worked out in the program.
A: There are 400 steps per revolution so the amount of movement depends on drive screw pitch or belt teeth. The resolution (steps per unit length) can be set in the software for your particular application.
Q: Are there any Z axis height controls over there that would work with your programme?
A: Our software will run all 3 axes simultaneously. If you have the code, it will run it.
Q: How does the MyT'Mill do in making wax jewelry parts? is the resoulution fine enough to do jewelry design with the mill.
A: I do not believe the resolution would be fine enough for that application. Even though the machine has anti-backlash nuts and anti-backlash software compensation, in reality, the resulting accuracy is still +/- ~.002". I would think jewelery design would require accuracy in the +/- .0001 range which you can only get from a zero-backlash ball screw design. These are very expensive machines.
Q: In your description of the mechanical properties of your MyT'Mill product you mention that it is not intended to machine steel under CNC. Other manufacturers of similar products don't mention this limitation, I even think that I saw an add for one that said that it could. Why can't your machine do this? Is it because of the holding torque rating of the motors? Please explain in laymens terms.
A: For the unipolar drive, even in aluminum, top speed is only around 1/2" per minute before the stepper motors begin to "slip". While I do have one customer that uses it for very light steel work, I do not emphasize it because people would have too high of expectations and I'd end up getting machines returned. It works best for cutting wood, plastics, and engraving in metals. The Pro model now comes with 250 oz-in motors so it can handle shallow cuts in steel.
Q: How large of an object, say a plate, can be milled? Is this just limited by the Sherline Mill?
A: 4"x8", limited only by the Sherline Mill.
Q: I know that steppers give like 200 steps per rev. I have seen some controllers advertising up to 1600 per rev. Are they worth the extra money?
A: 1600 steps/rev is accomplished by a hardware technique called microstepping. However, power decreases during microstepping because only a fraction of the windings are engaged at any one time. These controllers are more expensive, and in my opinion, not worth the extra money. Our controllers use half stepping (400 steps/in) to give a resolution of 0.000125 in/step using Sherline's 20 thread/in screws. That is more than the average guy can ever need.
Q: I need to do some circular stuff. If I want to mill a round hole in a plate, say 3 inches in diameter, how smooth can I get the hole? Will it require a lot of post milling smoothing?
A: The software breaks curves and circles into 0.5 deg line segments by default. Using just your finger or eyes, you would not be able to tell the hole was not perfectly round. However, if you want even better accuracy, the software lets you adjust the curve resolution to as small as 0.1 deg.
Q: If I wanted to get a 4th axis, to engrave around a cylinder, say, is there a way to do that?
A: Yes. The Pro controller now supports a 4th axis. Depending on the gear ratio, you'd have to enter the correct resolution (ie. steps per degree) for your application.
Q: I am very interested in making prototype printed circuit boards. Does your software allow you to create circuit boards from magazine images scanned into a computer. Exactly what steps and what software are required to produce a circuit board as shown on your samples pages?
A: The software can only input DXF files which is a vector format, not bit-maps like scanned images. There is software out there (probably even shareware, try www.shareware.com) that will "vectorize" a scanned image. These programs are notorious for producing poor results however. You could print out the circuit on a transparency and tape it to your screen, then trace the lines with a CAD program. Or, programs like Autocad let you import a bitmap picture and you could trace over it there. In any event, you must end up with a file of lines, circles and arcs. Another limitation with machining circuit boards is the space between traces. Engraving cutters only go as small as about 0.030" and often complicated circuits have smaller spaces than that between traces. But if you have a relatively simple circuit like shown on this web site, it works great. Another thought, you could tape the drawing to a board and mount the board on the Sherline table. Then with the controller on, trace the lines in jog mode and note the coordinate readouts on the screen for each end point. You could be building the G-code right at the same time your tracing the lines.
Q: Could you please explain in detail how to do the change over from word art to dxf so I can do it myself.
A: The procedure will depend on the CAD software you use. I used Autocad LT to convert it as follows:
1) In MS Word or MS Publisher, choose word art or clip art that looks like it will convert to lines easily. Avoid images with shadows in it. Those do not convert well as the shadows turn into many little lines that cross over the lines behind it. You will just have to experiment to see what works well and what doesn't and you'll get a feel for it after a while.
2) Select the word-art object then do Edit|Copy
3) Go into Autocad and do Edit|Paste Special
4) When it asks "paste as bitmap" or "paste as Autocad entities" choose Autocad entities
5) Hit enter several times to accept the default scale factor, orientation, etc.
6) Once pasted, select the object, choose Modify|Explode command to break it up into little pieces (lines, circles and arcs).
7) For good measure, explode it again just to make sure there are no sub-groups embedded in the main group.
8) Do File|Export (maybe File|Save As in some packages) choose DXF, hit OK.
9) Import into MyT'Mill for Windows.
10) If very little shows up, it did not get exploded enough. If that happens, you can use the software included on DeltaCad disk 2 called keycad.exe. Import the DXF file into it and use it's explode command to break it up. Then save the file, load it back, and write the DXF file. Saving and reloading before writing the DXF file assures a clean copy with nothing extraneous in memory that may cause problems.
Q: I would like to purchase an electronic edge finder but did not see one in the sherline catalogue and all the ones in the McMasters catalogue are too large. What are your recommendations?
A: I'm not sure what an electronic edge finder is. You could set up one edge to work off the emergency stop (pin 10). When pin 10 voltage goes to 0 (grounded via Normally open momentary switch to pin18,19,20,21,22,23,24 or 25), all motion stops if that option is turned on in preferences. I will be implementing code to find "home" using pins 11,12,and 13 later this year. That may work better for you.