XZ-Axis Gantry

Last Update: 10 October 2019

Assembling the XZ-Axis Gantry

Assembling the Delrin anti-backlash nuts

Parts needed:

  • 4pcs Delrin anti-backlash nuts
  • 8pcs M5-nylock nuts
  • 4pcs M5-25mm screws

We’ll be preparing these blocks for installing onto the XZ-axis gantry and eventually on the Y axis as well. Start by pressing in the M5-nylock nuts into the hexagonal cutouts. Make sure that you point the round end of the nut towards you, as you want the first part of the thread to be metal before your bolt gets to the nylon locking part.

Your kit will come with a set of set-screws and nuts that are used to tension and reduce backlash. However, they are quite short, and hard to get to for adjustment when your machine is assembled. We’ve included extra M5-25mm screws that you can screw into your Delrin anti-backlash nuts instead.

Prepare all of your blocks and set them aside for later.

Assembling the Z-axis motor mount and lead screw assembly

Parts needed:

  • 1ps 3D printed Z-axis mount
  • 1pcs steel Z-axis motor mount
  • 1pcs 200mm lead screw
  • 1pcs NEMA 23 motor with threaded M5 holes
  • 2pcs 608ZZ flange bearings
  • 1pcs 132mm GT2 closed loop belt
  • 1pcs 20T 6.35mm GT2 pulley
  • 1pcs 20T 8mm GT2 pulley
  • M5-nylock nuts
  • M5-25mm screws

Start off by pushing in two M5-nylock nuts into the hexagonal holes in the 3D printed Z-axis mount. These will be used to mount the steel Z-axis motor mount.

Make sure to keep the round part of the nut facing towards you when pushing them in.

Mount the NEMA 23 motor with threaded M5 holes onto the steel plate using four M5-25mm screws loosely. Note that only one motor in your kit will have threaded holes, and is marked with a sticker. We will be adjusting this part and re-tightening the screws later in the assembly. Make sure to also face the motor connector in the right direction before assembling everything together.

Keep the screws loose for now so that the motor can slide back and forth on the slots. You also want to make sure the plug on the motor is facing towards the rear.

Fit the motor and plate assembly into the 3D printed Z-axis mount. If it doesn’t slide in easily, try sliding the motor all the way forward, and tilting the plate back slightly.

Moving the motor back and forth, and tilting the plate and motor back and forth can help get this part in place.

Grab your two 608ZZ flange bearings and push them into the top and bottom bore on your assembly. You should be able to get them on easily with your thumbs. If you find resistance, try adjusting the steel plate so that the bores on the plastic and steel line up.

Bearing on the top.
Bearing on the bottom

Using two M5-25mm screws, secure the plate and the 3D printed part together. Your screws should thread into the nuts that were placed in the 3D printed part earlier.

Find your 200mm lead screw and an ACME locknut. Thread the ACME locknut about an inch and a half down the length of the lead screw. Make sure your locknut has an M3 screw for later locking it in place.

Thread your locknut about an inch and a half down the lead screw

Next, slide the short end of the lead screw into the 608ZZ flange bearing. Don’t push hard, your lead screw should slide in with little force. If you’re having trouble getting the lead screw to go in, try wiggling the lead screw back and forth gently.

The lead screw should slide into the bearings without needing much force.

You’ll find two 20T GT2 pulleys that look similar but have different bore sizes. Match the one with the larger bore with the lead screw. Loosen the set screws and slide on the pulley onto the top of the lead screw. The top of the pulley and the lead screw should be flush with each other. Tighten the set screws on the pulley to secure it.

You might have to adjust the ACME locknut to make the lead screw and the top of the pulley flush.
Use an allen key to tighten the set screws to hold the lead screw.

Once the pulley is secure, turn the ACME lock nut to sandwich the two 608ZZ flange bearings between the pulley and the ACME lock nut. Once in place, tighten the M3 screw to hold the ACME lock nut in place. Check for any play up and down. Adjust and tighten if necessary.

This step sandwiches the bearings together and keeps the lead screw constrained in the up and down axis.

Grab the second GT2 pulley with the 6.35mm bore and 132mm belt, and loop it around both pulleys as shown in the photo. Make sure that the set screws on your second GT2 pulley are out enough to let the pulley slide onto the shaft of the NEMA 23 motor. Slide the pulley on, and pull the motor forward on the slots if you need extra room.

Move the motor forward and put the pulley for the motor side in place.

Position the pulley so that the belt runs straight in line with the lead screw pulley. Secure the motor pulley by tightening the set screws. Make sure to line up one of the set screws with the flat part of the motor shaft to provide extra security (as shown in the photo).

Look for the flat part of the motor shaft and line up one of the set screws.

Next, make sure that the belt is tight around the two pulleys by pulling back the motor in the slot and tightening the M5 screws that are holding it in place.

Belt loose.


Belt tight.

Assembling the XZ-axis gantry Delrin v-wheels and anti-backlash nuts

Parts needed:

  • 4pcs Delrin v-wheels
  • 2pcs Delrin anti-backlash nuts (pre-assembled from a previous step)
  • 2pcs eccentric nuts
  • M5-25 screws
  • M5-25 nuts
  • M5 washers

First, check that the movement of your XZ-axis gantry is smooth by moving the Z-axis gantry up and down by hand. There should be no binding and the gantry should move relatively smoothly.

Gantry should move smoothly with no binding. Move up and down for a minute if tight.

Fit the two eccentric nuts into the pair of holes. The round part of the bore should sit inside of the hole, with the hex part facing out.

Make sure to have the eccentric nuts in the right holes, and that the bore is sitting inside the hole.

Next, grab a M5-25mm bolt, Delrin v-wheel, and M5 washer. Assemble together as shown in the photo. It is very important that the washer is in the correct place, as it keeps the wheel from rubbing against the gantry, as well as providing the correct spacing between the gantry and the lead screw. You will be doing this for all of the v-wheels on your LongMill.A washer is used to space the v-wheel away from the gantry.

Install the v-wheels with the eccentric nuts.

Install the first two v-wheels from the other side.

Now, we’ll put the bottom two wheels. Instead of using eccentric nuts, we’ll be using regular M5-nylock nuts.

These are the two holes which we’ll put the next two v-wheels into.
Install the v-wheels, ensuring that the washers are in place as well.
Tighten the wheels until snug.

Once complete, all of your wheels will be facing the backside of your gantry. Check to make sure that each wheel turns smoothly.

All of your wheels should be facing the same way.

There are two Delrin anti-backlash nuts that are on this part of the assembly. The first one we will assemble goes on the X axis gantry.

Two holes for mounting the Delrin anti-backlash nut.

Use two M5-25mm screws to mount the Delrin nut. Make sure that the nuts are facing outwards so that it keeps the nut in place. Make sure to not over tighten this part, just until it is snug.

Tighten until snug, but do not overtighten.

Now we’ll do the same process on the Z-axis on the two holes shown.

The two holes we’ll be using to mount our next nut.
Screw in the next Delrin nut, making sure not to overtighten.

The completed assembly should look like this.

Completed assembly.

Attaching the Z-axis motor mount and lead screw assembly to the XZ-axis gantry

Parts needed:

  • Z-axis motor mount and lead screw assembly (assembled from a previous step)
  • XZ-axis gantry with Delrin v-wheels and Delrin anti-backlash nuts (assembled from a previous step)
  • 2pcs M8-25mm screws
  • 2pcs M8 nuts

Line up the 200mm lead screw with the Delrin nut on the Z-axis. Use your fingers to turn the lead screw to help in go into the nut.

If you have trouble getting the lead screw to turn, try loosening the M5-25mm screws holding the Delrin nut in place and the screw tensioning the nut.

Continue turning the lead screw until the 3D printed Z-axis mount is fully seated into the top of the plate and you can see the holes line up that we will be putting M8 screws through.

Move the mount side to side as well to make sure that the holes are lined up and you can see through all of the holes.

Take two M8 nuts and push them into the back of the 3D printed Z-axis mount.

You might need to use a tool to help you push the nuts in all the way.

Take two M8-25mm screws and go in from the front to mount the Z-axis motor mount and lead screw assembly.

Screw in the M8 screws. Keep a finger on the M8 nuts if you are finding they pop out when you first start tightening the bolt.

Your assembly should now look like this.

Completed assembly (up to this point).

Attaching the aluminum router mount

Parts needed:

  • XZ-axis gantry assembly (up to now)
  • Aluminum router mount
  • 4pcs M5-12mm screws

The Z-axis gantry plate comes with two sets of holes which allow you to choose where you want to mount your router. You may choose to change where your mounting point is based on the type of router you have and the general type of projects you want to do.

The general rule of thumb is to mount it in the position that will have the Z-axis to move as close to the middle of the axis the majority of the time.

If you aren’t sure, we’d recommend starting out mounting it on the top set of holes.

There are two sets of holes on the Z-axis plate for the router mount.

Each router mount comes with four threaded holes that let you screw 4 M5-12mm screws. Move the Z-axis gantry to a spot that allows you to bolt it in from the back and use an allen key to install it.

Use the four M5-12mm screws to mount the router mount.

Your final assembly should look like this. Congrats, you’ve completed the assembly of the XZ-Axis Gantry!

That was fun, wasn’t it?