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### Question #: 245

Question: HOW CAN I DETERMINE THE DOSE EQUIVALENT (MREM/HR, MREM/WK, MREM/YR) USING RAW DATA FROM A TLD (THERMOLUMINESCENT DOSIMETER) THAT WAS PLACED IN AN OFFICE FOR 22 DAYS?

Current Solution

Assumption 1: The "raw data" of 24 mrem on the TLD is the total dose received by the TLD during the 22 days that the TLD was deployed in your office. This means that (1) any TLD reader background signal has been properly subtracted, (2) the signal accumulating in the TLD during any transport or storage time between preparation (annealing) and deployment in your office has been properly subtracted and, (3) the signal accumulating in the TLD during any transport or storage time between removal from your office and processing (reading) has been properly subtracted.

With this assumption, the total dose rate in your office is (24 mrem)/(22 days), or 1.091 mrem per day. The reference background is given as 63 mrem per year which is (63 days)/(365.25 days per year) or 0.172 mrem per day. Thus the average net dose rate to the TLD during the 22 days was (1.091-0.172) = 0.919 mrem per day.

Assumption 2: The net dose rate of 0.919 mrem per day in your office is attributable to the accelerator or other regulated sources under the control of your institution.

Assumption 3: The office occupancy factor of 1/4 attributed in your question to NCRP Report 49 was misread from Table 4. The correct occupancy factor given in NCRP 49 for offices is 1.

Assumption 4: You take 20 business days per year off for vacation and holidays. You work in your office for the remaining 240 days per year.

Assumption 5: All of the accelerator shots occur while you are in your office.

Assumption 6: The average net dose rate of 0.919 mrem per day determined during the 22 days of measurement continues for a year.

Based on the data that you provided and my assumptions, your annual dose received in your office from the accelerator or other regulated sources at your institution is predicted to be (0.919 mrem per day) x (240 work days per year) = 220 mrem.

Tom Gesell, PhD

Respond:

### Other Possible Solutions to this Question

• I need the calculation to determine the stepper motor torque to find the load that it can withstand in horizontal position using a lead screw at 1/2" diameter with 13 TPI.

There are two main questions that we can answer with respect to motor torque and the mechanical advantage of lead screws, 1) What torque motor do you need to lift a particular weight, or 2) What maximum weight will my motor torque be able to lift.

This formula uses Newtons (N) as it's final unit. Use this with the included radius (R) to determine the torque. Newtons can easily be converted to lbs or ounces using online conversions.

Effort = Sf + (Load/(2 x pi x (R/p) x Se))

where:
p = pitch of the screw
Se = screw efficiency = Standard lead screw will be between 20% (.2) and 40% (.4)
Sf = static force. This is the force that is needed to start the movement. The number may be eliminated, but it is good to use a number in the 5 N to 20 N range.
Load = the expected load that the effort will need to carry (i.e., the router and the included axis assembly that the motor will need to lift)

This formula is based on the "law of the machine"

The final effort amount with its unit of newtons and R will be the torque. For example, if the effort comes to 100 N (newtons) and the R is .5 inches, then you can assume that the effort is 50 N-in since it would take twice the effort to turn form the one inch mark from the center of the shaft.

Example:

Load = 90 N (20.2 lbs)
R = 1 inch since that is the length from the center of the shaft that the motor is rated
p = 1 inch / 13 = .08 inches

Effort = 5 N + (90 N / (2 x 3.14 x (1 / .08) x .2))
Effort = 5 N + (90 N / (6.28 x 12.5 x .2))
Effort = 5 N + (90 N / (15.7))
Effort = 5 N + (5.73 N)
Effort = 10.7 N = 2.4 lbs = 38.4 oz-in

I am putting the oz-in on the end because the formula considers the distance from the center of the shaft to be one inch.

Therefore, a 425 oz-in motor would be able to lift a 20.2 lb Router with its accompanying assembly. If the assembly and router is heavier, plug in the numbers and determine the effort required.

With a bit of algebra, the formula can be rewritten to find the load:

Load = (Effort - Sf) x (2 x pi x (R/p) x Se)

Another formula that does not consider friction at all:

Effort = (Load x p) / (2 x pi x R)

Lets see if we get similar results:

Effort = (20 lb x .08 inches) / (2 x 3.14 x 1)
Effort = 1.6 / 6.28 = .255 lbs = 4.08 oz-in

The results from both formulas appear to be very small because a 13 TPI screw will have enormous mechanical advantage.

It is evident that the first formula that does consider friction that we are loosely estimating is far more conservative than the second formula. Either way, even the most conservative formula shows that the 425 oz-in motor will handle very large weights. If you are using a lead screw with only two turns per inch, .5 inch pitch, you can determine the requirements with the first formula.

Example for a 10 TPI 5 start (2 turns per inch) lead screw:

Load = 90 N (20.2 lbs)
R = 1 inch since that is the length from the center of the shaft that the motor is rated
p = 1 inch / 2 = .5 inches

Effort = 5 N + (90 N / (2 x 3.14 x (1 / .5) x .2))
Effort = 5 N + (90 N / (6.28 x 2 x .2))
Effort = 5 N + (90 N / (2.512))
Effort = 5 N + (35.83 N)
Effort = 40.828 N = 9.18 lbs = 146.88 oz-in

Customer Response:
thank you so much

how do i calculate torque of stepper motor if lead screw coupled to motor shaft and load applied by lead screw on plate is 100 kg by vertically

Pls

1m 16mmdiameter ball screws calculations

What is the max load that 2 NEMA 17 stepper motors (spaced 2 feet apart, both will be pushing up on the same gantry) can lift while using a rod with the following specifications T8 OD 8mm Pitch 2mm Lead 4mm for each motor.

1

I need the calculation to determine the stepper motor torque to find the load that it can withstand in horizontal position using a lead screw at 1/2" diameter with 13 TPI.

• I need the calculation to determine the stepper motor torque to find the load that it can lift using a lead screw at 1/2" diameter with 13 TPI.

There are two main questions that we can answer with respect to motor torque and the mechanical advantage of lead screws, 1) What torque motor do you need to lift a particular weight, or 2) What maximum weight will my motor torque be able to lift.

This formula uses Newtons (N) as it's final unit. Use this with the included radius (R) to determine the torque. Newtons can easily be converted to lbs or ounces using online conversions.

Effort = Sf + (Load/(2 x pi x (R/p) x Se))

where:
p = pitch of the screw
Se = screw efficiency = Standard lead screw will be between 20% (.2) and 40% (.4)
Sf = static force. This is the force that is needed to start the movement. The number may be eliminated, but it is good to use a number in the 5 N to 20 N range.
Load = the expected load that the effort will need to carry (i.e., the router and the included axis assembly that the motor will need to lift)

This formula is based on the "law of the machine"

The final effort amount with its unit of newtons and R will be the torque. For example, if the effort comes to 100 N (newtons) and the R is .5 inches, then you can assume that the effort is 50 N-in since it would take twice the effort to turn form the one inch mark from the center of the shaft.

Example:

Load = 90 N (20.2 lbs)
R = 1 inch since that is the length from the center of the shaft that the motor is rated
p = 1 inch / 13 = .08 inches

Effort = 5 N + (90 N / (2 x 3.14 x (1 / .08) x .2))
Effort = 5 N + (90 N / (6.28 x 12.5 x .2))
Effort = 5 N + (90 N / (15.7))
Effort = 5 N + (5.73 N)
Effort = 10.7 N = 2.4 lbs = 38.4 oz-in

I am putting the oz-in on the end because the formula considers the distance from the center of the shaft to be one inch.

Therefore, a 425 oz-in motor would be able to lift a 20.2 lb Router with its accompanying assembly. If the assembly and router is heavier, plug in the numbers and determine the effort required.

With a bit of algebra, the formula can be rewritten to find the load:

Load = (Effort - Sf) x (2 x pi x (R/p) x Se)

Another formula that does not consider friction at all:

Effort = (Load x p) / (2 x pi x R)

Lets see if we get similar results:

Effort = (20 lb x .08 inches) / (2 x 3.14 x 1)
Effort = 1.6 / 6.28 = .255 lbs = 4.08 oz-in

The results from both formulas appear to be very small because a 13 TPI screw will have enormous mechanical advantage.

It is evident that the first formula that does consider friction that we are loosely estimating is far more conservative than the second formula. Either way, even the most conservative formula shows that the 425 oz-in motor will handle very large weights. If you are using a lead screw with only two turns per inch, .5 inch pitch, you can determine the requirements with the first formula.

Example for a 10 TPI 5 start (2 turns per inch) lead screw:

Load = 90 N (20.2 lbs)
R = 1 inch since that is the length from the center of the shaft that the motor is rated
p = 1 inch / 2 = .5 inches

Effort = 5 N + (90 N / (2 x 3.14 x (1 / .5) x .2))
Effort = 5 N + (90 N / (6.28 x 2 x .2))
Effort = 5 N + (90 N / (2.512))
Effort = 5 N + (35.83 N)
Effort = 40.828 N = 9.18 lbs = 146.88 oz-in

Customer Response:
thank you so much

how do i calculate torque of stepper motor if lead screw coupled to motor shaft and load applied by lead screw on plate is 100 kg by vertically

Pls

1m 16mmdiameter ball screws calculations

What is the max load that 2 NEMA 17 stepper motors (spaced 2 feet apart, both will be pushing up on the same gantry) can lift while using a rod with the following specifications T8 OD 8mm Pitch 2mm Lead 4mm for each motor.

1

I need the calculation to determine the stepper motor torque to find the load that it can lift using a lead screw at 1/2" diameter with 13 TPI.

• I placed an order for a 4th axis with tailstock on Wednesday and was just wanting to check on the shipment status. I'm needing the item early next week and need to confirm that it will arrive in time. Thank you.

To determine the status of your order, simply log in and click on the "[My Account]" link at the top of the page. If you purchased as a guest, you will need to call the office to determine the status and get the tracking number for your order.

The office phone number can be found by clicking "Need Help?" is located at the top right of all buildyourcnc.com web pages.

• I used DSP controller for my CNC machine. How can I determine why my CNC machine produce different output as per my requirement. example, i make a design size 10mm x30mm in my design software, now, why is it that my cnc output is15mm x 65 mm?

The DSP controller uses its own pulses per unit (in your case, it's pulses per mm). That number is he same as steps per mm (or steps per inch if you are using that unit). Make sure that the pulses per mm is configured correctly for the machine mechanical components and the mircistep setting on the driver for each axis.

You will need to make sure the DSP's parameters match the specifications for motor tuning.

• I am using Windows 10 and my Shopbot PRT 4g uses Shopbot's proprietary software https://www.shopbottools.com/support/control-software. How can I determine if the 4th axis you offer will be compatible with my machine?

Generally, you’ll need to check what control software will need to be used with the CNC router. Our machines use industry standard electronics and control software that is nonproprietary so you can use just about any software out there with our machines.

Specifically, what software are you planning on using?

dear Sir,
I'm searching for the best one,I think that I have to learn more about that in order to be able to make the right decision.

If you are using a computer running Microsoft Windows, then I would recommend using Mach3 or Mach4. If you prefer Linux, then LinuxCNC is the best control software in my opinion.

• Placed an order for the cable set for the Pokeys57cnc interface on 10/20 but it is not showing up in My Account as being ordered. It was charged to my credit card and I have not had any info that it was received by you.

Sure, let me check.

Your order was shipped out on Tuesday (10/20/2020). I noticed that your email was not stored in the customer record when the order was made. I will send you the tracking number via email now.

• Can you preset an origin point on this cnc? How long does it take to jog over? (If I have the case that I using the same thickness of maple wood, and same jig everytime)?

Yes, you can preset an origin by zeroing the machine at the desired location before beginning your work. You can return to that exact point at any time, or you can specify an offset from that point to be the beginning point for the next machine operation (for instance when cutting several parts from one sheet of wood.) Jogging time varies by machine and application but would generally be a rapid move -- our default rapid setting is 400 inches per minute.

Can you preset an origin point on this cnc? How long does it take to jog over? (If I have the case that I using the same thickness of maple wood, and same jig everytime)?

• I purachased a bluechick from you in 2011. I am upgrading from a Porter-cable router to a 2.2kw spindle. Can you supply me with drawings for the spindle mount so that I can cut the parts?

We currently cannot release or sell any plans at this current moment! We apologize for this inconvenience, however if you email us at customerservice@buildyourcnc.com. We can help you get the current parts you will need, for a fully functional 2.2kW z-axis assembly.

I purachased a bluechick from you in 2011. I am upgrading from a Porter-cable router to a 2.2kw spindle. Can you supply me with drawings for the spindle mount so that I can cut the parts?

• I have received an email from you re my question Number 13956 and I want to make some inquiries re just the control board could you send me a email address as using the address that the email was sent to me keeps coming back.

You can ask the question on this customer Service section. The questions on this section get answered immediately, or faster than our email service.

• I am building a machine that requires 2 steppers to drive the Y axis, can you make me a redleaf system using the 651oz steppers that will work for me?

Yes, we can make a redLeaf system that has all 6A drivers for use with the 651 oz-in motors. We can also wire the electronics in a way that two of the drivers will use the pins of the same axis so that axis will drive two drivers and motors.

I am building a machine that requires 2 steppers to drive the Y axis, can you make me a redleaf system using the 651oz steppers that will work for me?

• I have a YL620 VFD and the 2.2 kw spindle. The programming that is on the buildyourcnc web site is different in the PO/PD parameters. Do you have the VFD settings for the parameters using the P00.00 format?

This will point you in the right direction.
http://vancura.biz/files/Documents/CNC/YL620-A%20Setup%20table%20190707.pdf

• I have a YL600 VFD and the 2.2 kw spindle. The programming that is on the buildyourcnc web site is different in the PO/PD parameters. Do you have the VFD settings for the parameters using the P00.00 format0

MY VFD SHOW E.O.C.A error

EOCA light on my VFD

• I have an engine NEMA 34 from Y axis on my green bull that do not response, I already check connections and everything seems to be OK, how can I check that the motor it's working properly or not?

If one or more motor is not responding, please follow the troubleshooting directions below:

For parallel Bob only! Make sure both the parallel and USB are connected.

Re-check wiring, and connections for continuity (no breaks in the wires) and check for correct wiring locations from driver to BoB.
Check dip switch settings on the driver.
Check components, by swapping the motors (ex. y-axis motor to z or x-axis driver and z or x-axis motor to y-axis driver) to check if motor functions on another driver.
Depending on software check step low active (mach 3) or invert pulse (planet-cnc) for the axis which is not responding.
Mach 3 - config/port & pins/motor outputs / Planet-CNC - file/settings/axes

I have an engine NEMA 34 from Y axis on my green bull that do not response, I already check connections and everything seems to be OK, how can I check that the motor it's working properly or not?

• I am interested in using the Mach3 USB interface board. I was wondering if there was a way to run a torch height controller with this board for use with a plasma cutter, and if so do you know of any THCs that will work. Thank you.

Yes, you can connect a THC, Torch Height Controller, with the Mach3 USB controller. The THC uses the inputs to determine if the z axis needs to move up or down according to the arc of the plasma torch. The THC connects its outputs to the inputs of the controller so the controller will be informed of the states of the plasma torch.

• The Datasheet link for the stepper driver seems to need Microsoft Office to open. Is there another way to open that data sheet link?

Fixed. The 3.0 amp driver datasheet has been converted to a pdf.

The Datasheet link for the stepper driver seems to need Microsoft Office to open. Is there another way to open that data sheet link?

• LIMIT SWITCHES FOR AXIS. THE PRINT SHOWS THAT YOU CAN WIRE LIMITS EITHER N.O. OR N.C. SO IF THIS IS CORRECT I WOULD NEED TO TELL BOARD IN SOFTWARE HOW LOOK AT THESE LIMITS, I'M GOING GET AN INPUT LOOSE DEPEND ON IT.

BYCNC Response:
This is correct. You will need to use a method appropriate for the software you are using. Also remember that NC switches are typically wired in series, while NO switches are normally wired in parallel.

User Response:
I am using the cnc planet software for your USB board. Are the limit configurations in this software?

BYCNC Response:
Yes, Planet CNC software is compatible with the use of limit switches. Configuration information will depend on your specific application. You can view Planet CNC's information here: http://www.planet-cnc.com/files/CNCUSBController.pdf

• I am building the 24" x 48" machine from the original book and i was wondering if anyone can provide me with the actual cutting area possible with that machine.

The cutting area is 20" x 40" for the book machine. This area is determined by the 2'x4' sheets that make up the bed of the machine. You can increase this area if you use larger sheets and adjust the gantry width by the same difference of the width of the sheets.

You can also use the plans from Woodsmith magazine to build a larger machine.
https://www.woodsmith.com/article/build-a-cnc-router-for-your-own-shop/

need cutting area of 25 x 49 what size of gantry

need cutting area of 25 x 49 what size of gantry

I am building the 24" x 48" machine from the original book and i was wondering if anyone can provide me with the actual cutting area possible with that machine.

• Can I connect a 36V power supply to 2.5 AMP Stepper Motor Driver. On the actual driver it shows 12V - 24V, but in the description and data sheet it indicates that it can accept 8V - 45V. Will I benefit from more powerful power supply. Thanks

The 2.5 amp driver can only accept a power supply between 12 volts and 24 volts. If a 36 volt power supply is used for this driver, the main driver chip will exceed its maximum voltage rating and cause failure.

If you need to spin your motor faster, you can either use a more appropriate driver (i.e. 3.0 amp driver) or you can change the mechanical parts so the axis has faster travel.

• USING MACH3, MY MACHINE STOPS IN THE MIDDLE OF A PROJECT. HOW CAN IT BE STARTED AGAIN FROM POINT STOPPED?

Dealing with a mid-stop cut via Mach3, you will have to be careful if it is intentionally or unintentional. If you desire to stop your machine while in the middle of a cut be sure to stop it when the machine is moving in an upward motion on the z-axis and the X/Y-axis are stationary. Then you can choose the point (G-code) where the machine was left off and click on the Run from here button on the Program Run screen (left hand side) right above the Reset button.
(Make sure spindle/router is running before hand!)

Now if the machine stops unintentionally, and was moving in either the X/Y-axis, then it will be difficult to run the machine from the original point dealing with the coordinates might have been lost due the the machine continuing motion but via Mach3 the machine has stopped.

If this occurs to fight this issue before hand, is marking your home with the spindle/router to make a hole were your home is. Although moving it manually back to home the machine can be off by the smallest amount and could cause an inconsistent cut. If accuracy is something that can not be risked, then you can home the machine about a 1/4" or 1/2" down from the original home to start your cut on the same material but loosing that small piece.

My typical go to solution is:

- Note the current g-code line where the machine stopped.
- If Mach3 errored and you cannot control the machine, Exit Mach3 - you may find that reset, stop does nothing to stop the spindle. When you exit mach3, the spindle will stop automatically.
- Restart Mach3. The DRO (Digital Readout) should show the correct coordinates where the machine position was before exiting Mach3.
- Scroll to the g-code line where the machine stopped. You may need to go a few lines prior to make sure you are not skipping any machining operations (which is why it is a good idea to learn the basics of g-code - don't worry, it's easy)
- Click on the "Run from Here" button.
- Mach3 will present you with a "Preparation Move" dialog box with the location that it will move to. If the coordinates shows a position that is into the material, make sure to specify a rapid height (clearance height) so the machine will move up first and then move to the location before moving down into the material. If the spindle is automatically controlled by Mach3, make sure to check the turn spindle on checkbox. If not, make sure the router or spindle is on before clicking OK.

My cnc router stops at gcode line 50,000 and cannot finish program. They are about 150k of lines total. I have Mach3 and have bought the additional line capability. Is 50,000 (or around that) the limit? Is Mach 4 hobby license better and in what ways? Thanks! Mike Huber

If you have a license for Mach3, then you should be able to run g-code indefinitely. I think there is something else going on.

If you have a license for Mach3, then you should be able to run g-code indefinitely. I think there is something else going on.
What else could be going on?

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USING MACH3, MY MACHINE STOPS IN THE MIDDLE OF A PROJECT. HOW CAN IT BE STARTED AGAIN FROM POINT STOPPED?

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