Conceptually it is straightforward to predict the radiofrequency (RF) exposure intensity at any point in the vicinity of a cellular radio base station antenna. Simply multiply the effective radiation power times the inverse square of the distance times the relative gain of the antenna in the direction of the interest. The relative gain in different directions is know as the antenna radiation pattern and is usually available from the antenna manufacturer in graphical or tabular form.

Unfortunately, in real life the calculations involved in base station antenna evaluations are quite complex and require expert knowledge and experience to deal with the many parameters that are involved. An excellent reference summarizing this process is the Federal Communications Commission OET Bulletin No. 65 titled "Evaluating Compliance With FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields," available on the Federal Communications Commission (FCC) website.

To assess the RF hazards associated with handheld cell phones it is necessary to predict the rate of absorption in the body of radiofrequency energy, a parameter called the specific absorption rate (SAR). This is a very complex calculation, and cell phone manufacturers often rely on measurements of SAR in fluid-filled cylinders or plastic containers in the shape of a head. The FCC requires cell phone manufacturers to provide this data to FCC. You can obtain the data for your model phone on the the FCC's website. Unfortunately only cell phones manufactured in the last couple years are listed here.

As to your question about keeping RF exposures within the safety code, please read the other questions posted on this website this matter. Cellular radio products that meet FCC requirements will be within the guidelines established by safety standards organizations for users' and public exposure to RF radiation fields.

Gary H. Zeman, ScD, CHP

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FIRST OF ALL, THANKS FOR DESIGNING A WONDERFUL SITE. MY QUESTION IS: HOW DO YOU CALCULATE EME (ELECTROMAGNETIC EMISSIONS) AROUND THE TRANSMITTER (ANTENNA) AT ANY GIVEN POINT AND WHAT ARE MEASURES TO KEEP IT UNDER SAFETY CODE?

You can find the datasheets to our motors be going to the the stepping motor category page https://www.buildyourcnc.com/category/nema and selecting the motor. This will bring you to the product page for the motor and all of the motor information will be found there.

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I would like to design my own CNC router around one of your electronics bundles, either the 3 Axis - Heavy Gantry or 3 Axis - All Large Motors. Do you have the data sheets for the motors so that I can use the dimensions in my model?

There are many possible options for making a lathe. Typically, a lathe is run by a spindle at the head stock (which you can find here https://buildyourcnc.com/SpindlesAndAccessories.aspx) which will rotate the object rather than a fourth axis, however you will need to create or buy the clamp mechanism of a regular lathe to hold the object in place. You will be able to control the on/off either manually or via software, but the speed (RPM) will have to be controlled manually.
You can create a more indexed alternative to a lathe by using our rotary axis at the head stock (found here https://buildyourcnc.com/item/axes-4th). either way, the tail stock center can be found here https://buildyourcnc.com/item/axes-4th. This will give you full control of the turning via software.

You will want to use linear rails and their associated bearing blocks (found here https://buildyourcnc.com/item/mechanical-rails-HIWIN-Linear-20mm and herehttps://buildyourcnc.com/item/mechanical-rails-linear-guide-rails-20mm) to run along the length of the item being turned and you will need linear rails to be run perpendicular (towards and away) to the object being turned that would hold either the blade (for a traditional lathe) or a spindle (for the indexed version containing the rotary axis).

Where you have linear rail, you will also need lead screw (found here https://buildyourcnc.com/item/mechanical-leadscrews-lead-screw-!5-5-starts-10-tpi) to transmit motion using motors (and drivers) of your choice also with various options (found here https://buildyourcnc.com/category/nema and here https://buildyourcnc.com/category/driver). You will need 2 - Drivers (either 3.0A or 6.0A, the 6.0A driver will be for our larger motors hence you will have more torque available) and 2 - Motor's (either our Nema 24's or Nema 34's, the Nema 24 will work with our 3.0A driver while the Nema 34 will work the 6.0A)
To control these motors, you will need a parallel breakout board and Mach 3 software to control the two axes (or three with the rotary axis) found here https://buildyourcnc.com/item/electronicsAndMotors-parallel-breakout-relay and https://buildyourcnc.com/item/control-SOFTWARE-mach3.

You will need couplings to couple the lead screws to the motor shafts (found here https://buildyourcnc.com/couplings.aspx). All of the miscellaneous hardware you need can also be found here https://buildyourcnc.com/Hardware.aspx.

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CNC Wood Lathe project - Would like to have the guts to a 2 axis DIY lathe. Can you let me know of a possible one stop shop solution? Would like it to be at least 40" on the X axis.

Yes, we can customize almost any size of a machine. 2'x16' is within the possible dimensions. For a customized machine that you do not see in the "Design Your CNC" section, you will need to contact customerservice@buildyourcnc.com and make the request there.

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I am interested in the "Design Your CNC" page. However I need an extra long table. Is there any possibility of designing a custom 2' x 16' CNC, or can two 2' x 8' tables be combined some how?

Unfortunately, end mills will dull over time and need to be sharpened or repurchased. We do not currently offer any sharpening service, but we have a large selection of end mills you can find here http://www.buildyourcnc.com/ProductsEndMills.aspx

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Hi, I got two different bits I use alot. The 1/16th and 1/32 end mills. I use them alot for making signs. They seem to be getting dull. They are very expensive so I was wondering can you sharpen these bits? Do you have a service to do this? Thank you

It appears that the LCD that you have on the vacuum pressure controller is damaged. You will need to remove the LCD (desolder the LCD) that is on the controller and resolder a new one.

Here is a link to the LCD used for that vacuum pressure controller:
https://newbiehack.com/categories/newbiehack-LCD_Displays_and_LEDs-LCD-16x2

Newbiehack is a sister website to buildyourcnc.

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I have a vacuum regulator pump controller that I purchased from you previously. The LCD display is now missing the bottom line of text. Have you run into this issue before? Can I just swap out the LCD displays or is a fix going to be more involved?

That sounds like a faulty pressure sensor on the board. Call us and we can make an exchange.

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I have bought the vacuum pump controller, but the displayed pressure shows always 35.53. How can I make it work?

Here are links to the sole pump and heat exchanger/fan. I am sending you amazon links sine I don't ahve listings of my pump and heat exchanger separately from my cooling system:
Pump: https://amzn.to/3R6zPbj
Fan/radiator (Heat exchanger): https://amzn.to/3UWOuqN

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I RECENTLY PURCHASED A REPALCEMENT 12V DC SWITCHING POWER SUPPLY, HOOKED IT UP BUR DID NOT THE PUMP AND RADIATOR. VERIFIED OUTPUT OF UNIT AT 12V. SO I'M ASSUMING ALSO NEED TO REPLACE CAN YOU SUPPLY ME LINK PURCHASE THEM?

Polabs prepared step by step user guide for PoKeys57CNC and Mach4 to try answering such questions. It is available in our downloads section: https://www.poscope.com/wp-content/uploads/downloads/Pokeys/LibrariesAndPlugins/Mach4 and PoKeys57CNC - step by step guide.pdf

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I need your assistance... I have two items left to setup on my Pokey57CNC and Mach4, Home switches and Spindle Speed. I have watched the videos, but they are for Mach3 and the screens are different in Mach4. Can someone please explain the setup of these two items in Mach4?

My apologies for not getting back to you. We always answer the phones during business hours, so I would try that first. Our emails on Monday generally is stacked up as we are closed during the weekend. We can try your g-code here. Please send the g-code to the techsupport@buildyourcnc.com email address and we will test the code to see if it works.

By the way, do you get movement on the planet-cnc UI screen?

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The program starts and runs normal. I have all the correct movement on the mill and the UI screen. Then one of two things happens. It either stops and resets all axis to zero in the middle of the part or it freezes in the middle of the part. When it freezes, it is not moving on the cnc or the UI screen. Sometimes after a freeze it will come up with an 'IO timeout error', but the only way to clear is to unplug USB and start over.
I will send my settings and g-code files over tonight. Please be sure to load my settings when running the g-code. No movement of the cnc is necessary as the controller will do these issues without power to any drives and just the USB board connected, on my board at least.

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I have a MK1 board that I just got running and I am having issues. Do you have an MK1 board at your shop that I can send you my G-Code to run? The freexing/zeroing in the middle of the program issue happens even with no step drives attached to the board.

Yes, the 651 oz/in motor requires a driver that is compatible to the motors (the motor will draw 6 amps max and the driver paired with this motor will be able to allow for a 6 amp draw). I would also recommend a 36 volt power supply for better high velocity performance.

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I HAVE ONE OF YOUR SMALLER STEPPER MOTORS RUNNING MY X AXIS BRIDGE CRANE AND IF IT IS MOVED TO FAST THE MOTOR SOUNDS LIKE SKIPPING STEPS WILL 651OZ REQUIRE A DIFFERENT POWER SUPPLY CONTROLER?

The dimensions of the optional table are 73" x 34".

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What are the dimensions for a black toe torsion box? The machine dimensions are https://www.buildyourcnc.com/FAQ/1178 but I do not know the required overhang. I assume the overhang needs to be 3/4 inch ...

When you have Jogged the motor using the Keyboard Jog header, did you also try Jogging it with the on screen arrows? If it is also inverted, you will have to invert the axis to move it in the direction you require: Planet-CNC/File/Settings/Axes/Reverse (check box) on the axis that is running in reverse.

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The on-screen jog works properly, but the keyboard jog header runs the motors backwards. I had played with the software reverse function too, but couldn't get the on-screen and the keyboard pendant to work in the same direction. That's what lead me to check my wiring (maybe I had wires going to the wrong side of the header), and then to suspect a possible firmware error. I get the same story with all three axes.

I wanted to see if anyone else has any experience with the keyboard jog header.

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On B-Y-CNC USB Controller, I built a Kybd Jog pad to connect with on-board header. Jog seems to be backwards (Y+ moves it in the Y- direction). I've checked wiring. Could there be an error in the firmware?

Can you provide the model number of your VFD?

Yes, I have the "YL600 - 2S - 2K20"

It just came with a small booklet that is all in Chinese...

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I WIRED MY VFD (2.2KW VERSION) AND TRIED TEST RUNNING THE SPINDLE. CONFIGURED TO YOUR SPECS ON THIS WEBSITE, ONLY ISSUE IS WE GOT AN ERROR CODE. ERR 02, DO YOU KNOW WHAT IS? OR HAVE A LIST OF CODES? THANK

Yes, the 651 oz/in motor requires a driver that is compatible to the motors (the motor will draw 6 amps max and the driver paired with this motor will be able to allow for a 6 amp draw). I would also recommend a 36 volt power supply for better high velocity performance.

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I have one of your smaller stepper motors running my X AXIS bridge crane and if it is moved to fast the stepper motor sounds like it is skipping steps will the 651oz stepper motor require a different power supply and controler?

Our SBR20 rails use M8 bolts and are suitable for use with 8020 aluminum or any other common machine material. We suggest the use of our ball bearing pillow blocks with these rails, which you can find on our website here: https://buildyourcnc.com/item/mechanical-rails-linear-ball-bearing-block

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HOW TO FIND WIDH 38 HEIGHT 26 LINER GUIDE RAIL

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What are the hole spacing dimensions for the Linear Guide Rail 20mm? I'm trying to figure out what size aluminum extrusion to purchase so I can mount these to it.

Can you provide the model number of your VFD?

Yes, I have the "YL600 - 2S - 2K20"

It just came with a small booklet that is all in Chinese...

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I wired my vfd (2.2kw version) and tried test running the spindle. I configured to your specs on this website, only issue is we got an error code. Err 02, do you know what this is? OR have a list of error codes? Thank you

Attaching two motors in parallel is possible, but you will need another motor and driver for the opposite side. Each motor must have its own driver to work accordingly and fluently. The two can be wired together, to the same pins on your breakout board and set the dip switches on the driver to match the ones on your x-axis(ex). But remember to view the orientation of the motor and which way it spins, since it is on the opposite side it will have to be orientated correctly to move in sync with the other motor.

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I just finished building my first CNC with the electronics I purchased from you and I am already thinking about improving it. I would like to build a 2 motor X axis solution. Is it possible to attach 2 parallel motors and drivers to the BlueBrew Breakout Board? If so, how?

Most likely, the driver is not receiving the high or low signal for the direction terminals. The way direction works for an axis is the controller will output a high signal (5V) for one direction and low signal (0V) for the opposite direction. If the signal is always at one signal, say 5V, whether it is commanded in one direction or the other, then the axis will only move in that direction.

To solve this problem, make sure that the wiring is secure at both ends (from the controller to the driver). Also, make sure the Dir+ and DIR- are both wired correctly (i.e. the Dir- is connected to the signal gnd on the controller and the ZD is connected to Dir+ on the driver.

You can use a multimeter to determine the voltage at the ZD terminal by:
- setting the multimeter to DC voltage (the V with a straight line, or dashed line above the V)
- place the black lead on the gnd terminal
- place the red lead on the ZD terminal
- press the page up button and check the voltage
- press the page down button and check the voltage.

You should see the voltage change from 0V to 5V or vice versa.

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Hi I have just set up my machine using a mach 3 USB board I can only get the Z to go in one direction Y and X are Ok I have check wiring and looked at video over and over what have I missed??