Jeff's 1000 x 800 Gantry Router Design & Build

[JeffZ]

Alright, here we go.

I want to start off by thanking everyone. There is so much useful information on this forum, without which I wouldn't feel comfortable attempting such a complex and expensive project.

Goals:
This is a hobby machine, I do not intend to make money with it.
I really enjoy the process of learning, designing, building and improving a machine. For me, this process is half the fun of it.
I'll use the CNC as a tool to help with all sorts of DIY projects and hobbies.
Things like making electric guitars, small furniture, fancy signs, inlays, simrig components, backlit acrylic panels...
I will be working primarily in hardwood, plywood and hard plastics.
Occasionally, I'll want to do some light milling in aluminium. The aluminium plates needed for this projects are a good example (motor pockets, adapter plates etc).

My tools:

• Tablesaw with a decent crosscut sled and a blade for cutting aluminium
• Router table / handheld router
• Drill press
• Mpcnc
• Drill press
• I do not have access to anything capable of machining steel

Requirements:

• Minimum work area: 800x600x80
• Materials: hardwood, plywood, hard plastics, aluminium

Current design: (shows Nema34 motors and taper lock pulleys, other options listed below)

• Parts can be made using my limited toolset
• Work Area: 1000x800x120
• Footprint: 1300x1100x720 (fits neatly in the corner of my garage, and leaves just enough room for an enclosure)
• Main Frame extrusions:
  
  • 3x 160x80S
  • 2x 80x80S
  • 3x 80x40S
• 20mm Aluminium Plates (Red)
• 15mm Aluminium Plates (Yellow)
• 10mm Aluminium Plates (Green)

More Pictures:

X Axis

Y Axis

Gantry


Not shown are cable management, endstops, timing belt covers, enclosure, table etc...
I want to get the design more or less locked in before I continue on that path.

Making the parts:

• I will order aluminium plates already milled flat (10mm, 15mm, 20 mm).
• Most plates have 90° and 45° corners. Those I can cut to size on my tablesaw.
• I'll use the mpcnc to mill the motor pockets and the holes needed to insert the FK/FF bearings.
• The mpcnc will also function as a "cnc centre punch" to mark all holes to be drilled on the press.

Spindle

• G-Penny 2.2kw water cooled + VFD

Linear Rails (from BST)

• 6x Hiwin HGR20
• 12x Hiwin HGH20CA

Ballscrews (from BST)

• X axis: 1 x SFU2010 (~1320mm)
• Y axis: 2 x SFU2010 (~1160mm)
• Z axis: 1 x SFU1605 (~400mm)

Estimated motor / mass:

• 1 Z motor: 12.38kg (27.3lbs)
• 1 X motor: 22.96kg (50.62lbs)
• 2 Y motors: 65.79kg (145.04lbs) + ~5 liters of sand/epoxy mix to fill the X axis 160x80S extrusion

Motors I'm currently considering:

• Lichuan
  
  • Nema24 LC60H2102 4.5Nm
  • Nema24 LC60H2127 5.5Nm
  Unfortunately, shipping (for 4 motors) is ~180€ from the Lichuan aliexpress store.
  Buying them locally is even worse, 800€ for 4 motors + drivers
  
  
• Stepperonline
  
  • Nema34 Stepperonline Nema34 ~4.5Nm
  Multiple choices with cheap shipping, but Nema34 might not be a good choice for my project

Drivers I'm currently considering:

• Lichuan LCDA86H
• Stepperonline CL86Y
• Stepperonline CLA86T
• HBS860H (these sketch me out because of how cheap they are...)

Belt drive:

• HTD 5m closed loop timing belt
• Motors will use standard BF keyway pulleys.
• Ballscrew pulley types I'm currently considering:
  
  • Standard AF/BF pulleys with grub screws. (feels flimsy, might slip)
  • Clamp type BF pulleys (could only find one seller, max 25 teeth with 15mm wide belt)
  • Taper lock pulleys (heavy, min 32 teeth)
  • DIY taper lock pulleys using ER collets.

Controller:

• AXBB-E running UCCNC

Power supply:

• 230VAC -> VFD
• 230VAC -> 60VAC -> stepper drivers

None of this is set in stone. I'm not in a hurry, and no parts will be ordered until I'm satisfied with the design.
This is how far I've gotten on my own. I'd really appreciate any critique / comments / suggestions / advice.

Thanks,
Jeff

[Kitwn]

Jeff,
Looks good so far, you've obviously put a lot of time and effort in already.

The most obvious weak point you will get picked up on is the gantry. That single piece of upright profile may be too flexible. The current preferred and proven design would have another piece laid horizontally below the one you already show. This will give you much greater rigidity in all directions on the beam itslf and make the fixing of the end plates more rigid. There are pictures of this in various places on the forum.

The only other piece of advice I would offer, especially for a hobby builder with a budget, is to check the standard sizes of materials you can get or if your supplier will do cut lengths. I had a problem with suppliers in Perth, Australia only being willing to supply whole 6m lengths of aluminium sections. This is a real problem if your design only wants 2m of one size or 6.2m of another.

Looking forward to seeing your progress.

Kit

[JeffZ]

Thank you for your advice!

The most obvious weak point you will get picked up on is the gantry. That single piece of upright profile may be too flexible. The current preferred and proven design would have another piece laid horizontally below the one you already show. This will give you much greater rigidity in all directions on the beam itslf and make the fixing of the end plates more rigid. There are pictures of this in various places on the forum.

Something more like this?


Or, if I want to keep the current gantry height:

The only other piece of advice I would offer, especially for a hobby builder with a budget, is to check the standard sizes of materials you can get or if your supplier will do cut lengths. I had a problem with suppliers in Perth, Australia only being willing to supply whole 6m lengths of aluminium sections. This is a real problem if your design only wants 2m of one size or 6.2m of another.

Fortunately the supplier I currently have in mind offers to (roughly) cut to size for a reasonable price.

[Kitwn]

Thank you for your advice!



Something more like this?


Or, if I want to keep the current gantry height:




Fortunately the supplier I currently have in mind offers to (roughly) cut to size for a reasonable price.

Thats exactly the idea though I think most of the drawings you will find on the forum use the same size section for both pieces. Whether that is for simplicity or there's a sound reason to do with equal strength in both planes I don't know.

Kit

[JeffZ]

I rendered a few more options. Maybe someone can share more insight.

215mm high gantry:
Option 1 (120x80 + 160x40)
This is the closest to what I currently have.
Not really much more expensive. Everything (motors, bearings) still fits neatly behind the gantry.


255mm high gantry:
Option 2 (160x80 + 160x40)
Fairly similar, but 40mm higher.


Option 3 (120x80 + 120x80)
Using identical extrusions.


Option 4 (120x80 + 160x80)
The expensive option.

[NB70]

If you use a certain size aluminium profile for the gantry (90 by 45 mm I think) you can mount the BK/BF ballscrew supports directly to it, which makes things easier.

[JeffZ]

If you use a certain size aluminium profile for the gantry (90 by 45 mm I think) you can mount the BK/BF ballscrew supports directly to it, which makes things easier.

My supplier does offer 45mm (B-Type) extrusions, but the choice is very limited.
Using my supplier, the only sensible option is the one you're showing, using 2 45x90 extrusions for a 90x135 gantry.

I prefer the 40mm (I-Type) extrusions. They're thicker, easier to tap, there's more compatible hardware, and I can get them in larger configurations, such as 160x80 and 120x80.
I don't mind using the FK/FF bearings, but you're definitely right that using BK/BF, bolted directly to an extrusion is both easier and more adjustable.

[JeffZ]

I had some more time today, and tried going through assembly / maintenance steps in my head, and I discovered some issues.

Once the Z axis is mounted, it is no longer possible to adjust the rails or the sleds.
To address this, I switched to the wider HGW20CC sleds and added access holes through the front plate so that they can easily be adjusted. I also changed how the spacer plates for the rails work, so that they can be adjusted through the front plate as well.
I also added extra holes to the side plates to allow direct access to the grease nipples on the sleds.


As for the X and Y axis, I flipped the FF bearings, so that I can install / remove the ball screws without having to disassemble half of the machine...

In terms of motors, I'm back to my initial choice, the Lichuan Nema24 LC60H2127 / LC60H2102 motors with LCDA86H drivers. For some reason the shipping cost on their aliexpress store has come back down to reasonable levels. Let's hope it stays that way until I'm ready to order...

For timing pulleys, I want to give these clamping type pulleys a try. For testing purpouses, I think I'll just order a couple of them and mount them onto some precision rod I have laying around, to test runout and how much torque they can take before slipping.
If they work well, I'll probably go with 25 teeth htd 5m pulleys.
Not sure if I should use 15mm or 20mm belt width though.

As suggested, I also modified the gantry layout from a single 160x80 profile to 120x80 + 160x40 profiles (L shape)

[NB70]

Its looking good Jeff. I've used a similar design for my gantry. I took a tip from Jazz-CNC that its easier to assemble & align it if you use 2 separate plates bolted together (see picture) - if you oversize the bolt holes it also gives you some room for adjustment / squaring. The whole gantry can lift then off and you leave the long axis ballscrew mount & linear bearings in place on the bottom plate.

[JeffZ]

Its looking good Jeff. I've used a similar design for my gantry. I took a tip from Jazz-CNC that its easier to assemble & align it if you use 2 separate plates bolted together (see picture) - if you oversize the bolt holes it also gives you some room for adjustment / squaring. The whole gantry can lift then off and you leave the long axis ballscrew mount & linear bearings in place on the bottom plate.

That is a fantastic idea. Thank you, I'm definitely going to implement this.