Are the Automatic Tool Changer Tool Holders separate from the actual bits?
Yes, the tool holders are special collets that you install the end mill into and place it on the tool rack. The tapered design of the top of the tool holder allows it to be grabbed and secured by the tool changer. Tool holders are available in 1/8″, 3/16″ and 1/4″ shaft sizes. Note: when you buy the Automatic Tool Changer, it comes with two 1/8″ tool holders and a rack that will hold up to 5 tools, so to fill the entire rack, you will need to order 3 more tool holders.
Does the Automatic Tool Changer require an air compressor?
Yes, it will require a small air compressor that is capable of outputting 110 PSI of air pressure. We use a small pancake compressor from Harbor Freight that we got for $119.00. They have pricing that ranges and sometimes you can get it for even less money. The direct link to the product is: https://www.harborfreight.com/3-gal-13-hp-100-psi-oilless-pancake-air-compressor-61615.html Note: You will need a 1/4 in. FNPT x 1/4 in. I/M Steel Plug fitting to match your compressor’s hose. Here is one from Home Depot: http://www.homedepot.com/p/Husky-1-4-in-FNPT-x-1-4-in-I-M-Steel-Plug-12234HOM/205330359
How do you set the tool lengths (Z height) for each tool in the Automatic Tool Changer?
We actually have an automated macro that will do this for you. The video below will explain how to do this. NOTE: This macro will require the Tool Length Sensor in order for this to work. Category: Automatic Tool Changer
If I order a STEPCRAFT with an Automatic Tool Changer, will you pre-install the tool rack and setup the software?
Yes we can pre-install the tool rack(s) for you on your machine. We will ALWAYS put them in the rear right corner (when looking from the front of the machine). Additionally, we will setup the tool locations in UCCNC and send you the Macro file that you can simply copy to your installation of UCCNC. Once complete, all locations should be correct and you can start using the ATC right away. Categories: Automatic Tool Changer, Common Pre-Purchase Questions
Will G-code created by any given CAD/CAM software work with EMC?
Not necessarily. Some “fine-tuning” may be required before G-code created by some CAD/CAM programs will run successfully on EMC or any other G-code control program for that matter because post processors create code for particular machines that are not all the same. EMC uses industry standards for G-code, but it is up to the manufacturers of CAD/CAM programs to adapt their product to EMC, not the other way around. For example, some unassigned G-codes may be used by one company to do one thing and by another company to do something else. Also, Sherline’s simplified system does not support all G-codes such as some canned cycles, limit switches, etc. EMC will not understand these codes. It will be necessary to pre-run the G-code in the backplot program and, if the program stops running and highlights an area of offending code, delete the necessary lines using the editor. This is why you will still need a basic understanding of G-code even if you are using a CAD/CAM program to generate it for you. As EMC becomes more prevalent in the CNC world, more software manufacturers will write specific post-processors for it, but Sherline has no input into that process or control over how these companies write their software. In the absence of a specific EMC post processor, we recommend you choose the “Mazak” or “Hurco” post processor as the best alternative to get as close as possible on 3-axis projects right from the start.
How fast will the stepper motors move the slides?
A fact when dealing with stepper motors is that the faster they turn, the less torque they have. This is because the power for each pulse is on for shorter periods of time; therefore, it’s a good idea to keep feed rates 20% below maximum when running programs with many short moves, particularly on the Z-axis. The maximum feed rate in EMC is 22 in/min. Therefore it is good practice to keep your feed rate below about 18 in/min or 450 mm/min. Some of our customers have counter-balanced the weight of the Z-axis with a simple rope-pulley-weight device to reduce wear on the Z-axis leadscrew. See the CNC Projects section of our website for a photo and description of how one person did this. You’ll find that the stepper motor system we use quite reliable and capable of running complex programs without losing steps when used properly. G-code tips: Start and end each program with a percentage sign. Put a g40, g49, g21 (Metric) or g20 (inch) and g90 in the first line of code to cancel out any previous codes that might be left over from the last program, and always end the program by returning to the same place you started. Keep in mind which G-codes EMC does and does not support. Some canned cycles are not supported, for example.
My machine is missing steps (inaccurate movements). How do I fix this?
The maximum feed rate that you can use on a Sherline machine is 32 in/min. The g-code can generate feed rates of 60 in/min and up to 240 in/min. When you put in feed rates that exceed the maximum feed rate of the machine, the machine will default to the highest feed rate possible. This means that regardless of what your programmed feed is, the machine is feeding at 32 in/min throughout your entire program. What is happening in this instance is that your stepper motors are stalling during the cut and missing steps. Because these are stepper motors, they do not send a position signal back to the computer to verify that they actually moved to the position that was sent by the computer. Your computer tells an axis to move a specific distance and then assumes that your stepper motor made it to that location when it stops. If your stepper motor stalls for a split second due to excessive feeds and it misses a step or two, your computer doesn’t know that. For a complete rundown on this topic, please visit the following link on our Blog page: My CNC Machine Is Missing
How do I use my inch CNC system in metric mode?
You can toggle between metric and inch modes by using a g20 or g21 code. A line of code beginning with “g21” tells the machine that all numbers you enter after the g21 are now in millimeters instead of inches. The software will make the calculation to move the machine the correct metric distance using the inch leadscrew. Using the g20 code will allow you to switch back to inch dimensions or to enter inch dimensions on a machine with a metric leadscrew. So if you have an inch machine and always program in inches, why should you worry about it? Because EMC remembers the last code run even when the machine is turned off. Therefore, it is a good idea to always put in a g20 in the first line of your inch program just in case the last program run had a g21 in it. On metric machines start with a g21 to similarly protect yourself from a g20 code in the previous program. When starting the EMC program, select the proper file for your machine; that is, on an inch mill, click on the desktop icon that says “CNC Sherline Benchtop Mill (Inch)” or for a machine with metric leadscrews, select the icon called “CNC Sherline Benchtop Mill (mm).” This tells the program what leadscrew pitch to assume in its travel calculations.
My stepper motors make noise, but nothing is moving. What should I do?
The likely problem here is your mill is binding or not properly lubricated. With the more significant stress of quick back and forth motions and the high number of turns possible in a short period of time your mill will need to be more frequently lubricated than hand-driven applications. Under continuous CNC use, we recommend that Sherline CNC mills be lubricated once every four hours. Refer to the mill manual or Lubrication PDF for more detailed instructions. Note also that when stepper motors are powered up but not yet running they do tend to make a slight buzzing or hissing noise. This is normal.