### Question #: 2358

Question:
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On the Book Build: I'm changing the 13TPI 1/2" lead screw with the 1/2" 10 TPI Acme screw with the anti backlash nut. This is for the Z axis only. What should I know about installing it and what are the numbers I need to plug into the motor tuning area.
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**The settings that will have to be change will be your steps per inch in motor tuning (mach 3), or settings/axes(planetCNC). But we do not have the actual numbers/specs that will fit your 10 TPI 5 start lead screw, here is a tutorial video which explains how to get the exact numbers you need! (**

**).**

Here is a default setting that you might be able to tune and adjust accordingly: 1600 steps, accel 400.02, velocity 5.

Here is a default setting that you might be able to tune and adjust accordingly: 1600 steps, accel 400.02, velocity 5.

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### Other Possible Solutions to this Question

**On the book build machine I changed the Z axis from a 13 tpi lead screw to an acme 10 tpi 5 start lead screw. What numbers do I put into the motor tuneing boxes.**The settings that will have to be change will be your steps per inch in motor tuning (mach 3), or settings/axes(planetCNC). But we do not have the actual numbers/specs that will fit your 10 TPI 5 start lead screw, here is a tutorial video which explains how to get the exact numbers you need! (

)**Click the link to add information to this solution:**

On the book build machine I changed the Z axis from a 13 tpi lead screw to an acme 10 tpi 5 start lead screw. What numbers do I put into the motor tuneing boxes.**I just changed my X and Y to the ACME 1/2" 5 start lead screw. What are the motor tuning numbers. I have the book built machine.**The settings that will have to be change will be your steps per inch in motor tuning (mach 3), or settings/axes(planetCNC). But we do not have the actual numbers/specs that will fit your 10 TPI 5 start lead screw, here is a tutorial video which explains how to get the exact numbers you need! (

)**Click the link to add information to this solution:**

I just changed my X and Y to the ACME 1/2" 5 start lead screw. What are the motor tuning numbers. I have the book built machine.**thank you for the reply. I would be really good to know the calculation. The lead screw is 1/2" diameter with 13 TPI. Please provide the calculation for determing the maximum weight motor can handle on Z-axis on book build cnc. And one more question. If I am cutting 18mm MDF with 6mm cutting bit (so 6mm pass), what can be the maximum speed rate of cutting and spindle speed of router? thank you**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)

R = radius of the lead screw

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

Additional Information:

Additional Information:

Additional Information:

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

Additional Information:

Pls

Additional Information:

1m 16mmdiameter ball screws calculations**Click the link to add information to this solution:**

thank you for the reply. I would be really good to know the calculation. The lead screw is 1/2" diameter with 13 TPI. Please provide the calculation for determing the maximum weight motor can handle on Z-axis on book build cnc. And one more question. If I am cutting 18mm MDF with 6mm cutting bit (so 6mm pass), what can be the maximum speed rate of cutting and spindle speed of router? thank you**I have your Nema 24 electronics kit and am having problems with the Z axis dropping over time. I am using a PC 8902 motor. Any ideas on what the problem is? What should be the motor tuning values in Mach3? Thanks**Make sure all your bolts/screws are tighten correctly and if using a lead screw make sure your anti-backlash nut is not offset. Now a default setting will be 10101100 for your driver dip switch settings and in motor tuning (mach3) 1600 steps per, 400.02 velocity, 4 in acceleration. now the acceleration and velocity can be adjusted to move your machine faster, but if set to high they could stall. Make sure you have the correct wiring from your motor to your driver (https://www.buildyourcnc.com/Documents/PN.SM60HT86-2008BF-U%20(inhouse%20PN.60BYGH303-13)%20(1).pdf).

**Click the link to add information to this solution:**

I have your Nema 24 electronics kit and am having problems with the Z axis dropping over time. I am using a PC 8902 motor. Any ideas on what the problem is? What should be the motor tuning values in Mach3? Thanks**Regarding 1/2" 5 start and 10 TPI ACME precision lead screw, what the maximum length you can ship within USA? I'm looking for something like 100" and I could use a 1" screw if available. Please include estimated price. Thanks.**The maximum length we can ship is a total of 78" inches. However we can send your required length in portions. Please refer to adding the total items you require to your cart to get a visualized amount and shipping cost.

**Click the link to add information to this solution:**

Regarding 1/2" 5 start and 10 TPI ACME precision lead screw, what the maximum length you can ship within USA? I'm looking for something like 100" and I could use a 1" screw if available. Please include estimated price. Thanks.**Since I am using normal all-thread lead screw 13 TPI 1/2" for the book build cnc, what can be the maximum feed rate of machine and how can I change the mechanical setup in mach 3? I am using 1/4" steel carbile endmill with 2 flutes and router is 2 HP with variable speed**Book build (scratch build), feedrates and recommendation.

Using standard allthread will provide around 20-30 ipm using 36 volts. Although it allows for a working CNC machine, the RPM of the spindle/router will need to spin at the lowest setting to provide the beat efficiency and life for the end mill at 1/4" cut diameter and higher. The speeds may be fine for smaller end mills.

If you would like faster speeds, you should change the lead screws on the CNC machine to the 1/2" 5 start 10 TPI which translates to 2 turns per inch which means, the stepping motor will not need to turn as fast to produce faster motion. That is to say, the stepping motor will only need to turn two revolutions for the machine to travel one inch and with the allthread, the stepping motor will need to turn 13 times to reach one inch.

Link to the lead screw and other mechanical parts needed:

https://www.buildyourcnc.com/CNCMachineMechanicalParts.aspx

To change the lead screws you will need (for each axis):

1. The lead screw for that axis.

2. Two 1/2" collars to keep the lead screw axially stable.

3. One Antibacklash nut.

Additional Information:

20**Click the link to add information to this solution:**

Since I am using normal all-thread lead screw 13 TPI 1/2" for the book build cnc, what can be the maximum feed rate of machine and how can I change the mechanical setup in mach 3? I am using 1/4" steel carbile endmill with 2 flutes and router is 2 HP with variable speed**BUILDING ONE OF YOUR GREENBULL 6X LONG AND 2.2 KILOWATT SPINDLE DOES NOT FIT. SEEMS LEAD SCREW YOU SENT WITH KIT IS SHORT 42" LOOKS LIKE IT NEEDS TO BE 5 OR 6 INCH LONGER. THIS CORRECT? WHAT THE NEEDED LENGTH FOR UNIT?**The leadscrew length for the greenBull long Z-axis is 47 inches.

**Click the link to add information to this solution:**

BUILDING ONE OF YOUR GREENBULL 6X LONG AND 2.2 KILOWATT SPINDLE DOES NOT FIT. SEEMS LEAD SCREW YOU SENT WITH KIT IS SHORT 42" LOOKS LIKE IT NEEDS TO BE 5 OR 6 INCH LONGER. THIS CORRECT? WHAT THE NEEDED LENGTH FOR UNIT?**THE LEAD SCREW IS VERY HARD TO TURN. BACKLASH BUSHING SEEMS BE TOO TIGHT AND BINDING ON SCREW. DO IT NEED LUBRICATION OR DID DAMAGE NUT WHEN INSERTING SCREW?**Yes, you can use lubrication, like 3-in-1 oil to make it a bit easier. You will need to run it up and down to break it in.

Additional Information:**Click the link to add information to this solution:**

THE LEAD SCREW IS VERY HARD TO TURN. BACKLASH BUSHING SEEMS BE TOO TIGHT AND BINDING ON SCREW. DO IT NEED LUBRICATION OR DID DAMAGE NUT WHEN INSERTING SCREW?**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)

R = radius of the lead screw

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

Additional Information:

Additional Information:

Additional Information:

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

Additional Information:

Pls

Additional Information:

1m 16mmdiameter ball screws calculations**Click the link to add information to this solution:**

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'm trying to build my CNC router 3m*1.3m, but i'm not sure what is the type of stepper motor i should pay, all my CNC body is Al. I need to bay 4 Stepper motors, 4 drivers, spindle, inverter, and i don't know what is the type of controller ?**The size of the stepper motor is measured in holding torque, generally oz/in. You will determine the torque loads of your axes when selecting steppers. Once you know which stepper you need, the drivers and controller board are simple to pair with them.

**Click the link to add information to this solution:**

I'm trying to build my CNC router 3m*1.3m, but i'm not sure what is the type of stepper motor i should pay, all my CNC body is Al. I need to bay 4 Stepper motors, 4 drivers, spindle, inverter, and i don't know what is the type of controller ?**How to determine lead screw length needed. My Thomson 1 1:4 rails are 60 inches long roughly for the router I’m building. I know I have to have it long enough to couple up with the stepper motor of course but does it matter if it’s a little long on the other end**It generally does not matter if it is longer at the other end as long as the lead screw provides the desired travel for that axis. The lead screw will only need to be long enough for the travel, plus any structure and lead-nut positioning.

For example:

- The motor that will turn the lead screw will need to be mounted at some position (generally at one end of the axis). In many cases, this positioning will be mounted where some of the lead screw will not be used (the lead nut will not be able to moved close to the coupling of the lead screw to the motor shaft). Add some of the length of the lead screw to be inserted into the coupling.

- If the lead screw will contain bearings at either end of the travel, that portion of the mechanical assembly will need to be considered in the lead screw length.

- The lead-nut will need to be mounted in a position on a structural member of the part that is to move. The distance from the part of the structure that will extend closest to the motor will have some distance to the position of the lead nut. This distance will need to be added to the lead screw length.

Add these discrepancies to the length of the lead screw and the travel length and you will have the final length.**Click the link to add information to this solution:**

How to determine lead screw length needed. My Thomson 1 1:4 rails are 60 inches long roughly for the router I’m building. I know I have to have it long enough to couple up with the stepper motor of course but does it matter if it’s a little long on the other end**I am installing a mach 3 usb controller into a wright cnc plasma table and I need instruction on wiring the thc (proma compact ) torch height controller to this board. IE will this board work to replace the parallel port board with usb controller board?**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.

**Click the link to add information to this solution:**

I am installing a mach 3 usb controller into a wright cnc plasma table and I need instruction on wiring the thc (proma compact ) torch height controller to this board. IE will this board work to replace the parallel port board with usb controller board?**Building one of your greenBull 6X Long and 2.2 kilowatt spindle does not fit. Seems lead screw you sent with kit is short 42" looks like it needs to be 5 or 6 inch longer. Is this correct? What is the needed length of lead screw for this unit?**The leadscrew length for the greenBull long Z-axis is 47 inches.

**Click the link to add information to this solution:**

Building one of your greenBull 6X Long and 2.2 kilowatt spindle does not fit. Seems lead screw you sent with kit is short 42" looks like it needs to be 5 or 6 inch longer. Is this correct? What is the needed length of lead screw for this unit?**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)

R = radius of the lead screw

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

Additional Information:

Additional Information:

Additional Information:

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

Additional Information:

Pls

Additional Information:

1m 16mmdiameter ball screws calculations**Click the link to add information to this solution:**

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 received the electronics for book build cnc machine. I need to know how much weight the z-axis motor can hold since my (craftsman) router seems to be heavy. It is 2HP with variable speed**The motor is helped by the mechanical leverage of the screw. The 425 oz-in motors that are included in the standard electronics combo has very high torque for that type of machine. You will have no problem using that motor for the book machine.

We use that motor for very heavy spindles on the blackToe and blackFoot CNC Machine kits.

You will need to do the mechanical leverage calculation along with the torque of the motor to determine the actual weight it will lift. The calculation will need to consider the type and pitch of the screw and it would also consider the gravity constant of 9.8 m/s/s.

If you need me to determine this formula and work out the calculation based on the screw you are using, please let me know.

Additional Information:

thank you for the reply. I would be really good to know the calculation. The lead screw is 1/2" diameter with 13 TPI. Please provide the calculation. And one more question. If I am cutting 18mm MDF with 6mm cutting bit (so 6mm pass), what can be the maximum speed rate of cutting and spindle speed of router?

thank you**Click the link to add information to this solution:**

I received the electronics for book build cnc machine. I need to know how much weight the z-axis motor can hold since my (craftsman) router seems to be heavy. It is 2HP with variable speed**I am building your "Green Bull' 6 foot wide kit and I am at the stage of attaching the motor and drive chain. I would like to know if you have an modification kit available to put the 1/2" ACME screw on the Y-axis?**Currently we do not have that modification kit, our set up is fixed for our greenBull only modification kit we have for this model is the long z-axis kit(Designed for Foam cutting).

**Click the link to add information to this solution:**

I am building your "Green Bull' 6 foot wide kit and I am at the stage of attaching the motor and drive chain. I would like to know if you have an modification kit available to put the 1/2" ACME screw on the Y-axis?**I'm assembling the gantry for a 5x10 greenbull and noticed that there are 9 spaces for torsion spacers but only 7 in the kit. Should I just space them out on the right side behind the motor?**That is correct. We send the fewer ribs than could be fastened within the gantry. One reduction of a rib will provide more space for the motor at the midpoint of the gantry and at the other side of the gantry (opposite the motor) can be reduced to provide more space to work with the coupling.

**Click the link to add information to this solution:**

I'm assembling the gantry for a 5x10 greenbull and noticed that there are 9 spaces for torsion spacers but only 7 in the kit. Should I just space them out on the right side behind the motor?**I have a lead screw machine I built from the book plans (i know, ancient history) and I'm thinking of converting the X and Y axis to rollerchain. Assuming I can configure my controller appropriately, is there anything I should buy besides chain, drive cog, tension cog and mounting hardware?**You want to make sure that the motors will be able to provide the necessary torque since there will not be mechanical advantage using roller chain. You will need a way to fix the chain to each end. I like to use #4 - 3/4" screws and #4 nuts. You will need a drive sprocket for each axis and a couple idler sprockets on each axis to serve as tensioners and guiding the roller chain.

Additional Information:

OK cool. I have NEMA 24 steppers rated 425 oz-in. Is there some rule of thumb I can use to guess if that's enough? I'm not planning to push against hard stock material.**Click the link to add information to this solution:**

I have a lead screw machine I built from the book plans (i know, ancient history) and I'm thinking of converting the X and Y axis to rollerchain. Assuming I can configure my controller appropriately, is there anything I should buy besides chain, drive cog, tension cog and mounting hardware?**I bought a blacktooth laser from you about a year ago.. I am finally getting around to installing the laser tube and I noticed that my tube does't have the metal end on it like all the pictures I've seen. is this a focus lense and can I purchase one?**As shown in the instructions the laser tube that was used was a different model which had the metal end, compared to our full glass tube models we currently ship with the machines.

So there is no difference besides appearance between the two tubes.

The focus lens should be placed in the laser nozzle assembly and not on the laser tube itself.**Click the link to add information to this solution:**

I bought a blacktooth laser from you about a year ago.. I am finally getting around to installing the laser tube and I noticed that my tube does't have the metal end on it like all the pictures I've seen. is this a focus lense and can I purchase one?