[Dytoven]

I am new to this world of cnc and I'm trying to build a machine for hobby in my house, I have the design and the materials used in mind but I would like an expert review before starting work.
Upload some pictures of the design and explain which components will use to see if the choice is correct.

Max. working stroke: Y-1400mm X-1050mm Z-300mm for all materials especially plastics and aluminum including steel occasionally, I would like that all work well but do not want to waste money. My budget is 5000€ with software included.

The material of the gantry is 10 or 15mm thick, aluminum profile 45x45 mm and 45x90mm, the gaps of the two towers are to save weight and extract material for two pieces of Z. The machine legs would 30mm polyethylene think it will have sufficient rigidity and is a little cheaper than aluminum, initially thought to make the whole structure of polyethylene but I'm not so sure that the gantry is sufficiently rigid.

I thought Nema 34 motors 3A, 5Nm in all axis. - Nema 34 CNC Stepper Motor 5Nm(708oz.in) 3.0A 34HS38-3008S - US$
In the driver does not know if I look for on the peak or rms. - Leadshine DM432C Digital Stepper Driver 18-40VDC with 0.3-3.2A - US$ Creo que Leadshine es un buen driver.
The power supply for each axis - Switching Power Supply 350W 60V 5.9A for CNC Router Kits 115V/230V S-350-60|S-350-60|Power Supplies
The breakout board - Aliexpress.com: Comprar Nueva calidad CNC 200 KHZ 5 ejes MACH3 USB interface board breakout tarjeta del controlador CNC de de garantÃ*a de producto fiable proveedores en Changzhou Rattm Motor Co., Ltd. (200khz like the driver?)
Ballscrew 32, 25 and 20mm with pitch 10mm in Y,X,Z.
For the spindle I've thought about 3Kw air-cooled I do not think doing very long jobs. Something like this - Aliexpress.com: Comprar Cnc Motor del huso refrigerado por aire eje Motor 3KW ER20 4 rodamientos 3KW VFD / inversor controlador de frecuencia variable de velocidad del husillo de control de control de frecuencia fiable proveedores en BEST Technology C
For software I've thought Mach3 or a new one I've found that seems a bit easier CNC USB Controller of Planet CNC. and Meshcam for CAM.
For the table I have the idea to do it with 30mm polyethylene in 4 pieces once the machine running, my first job will be to make the slots in the table.

I appreciate your suggestions before going ahead with the project, I have more doubts about the electronics and software for the rest I have some experience but all are welcome.

[ger21]

This machine will not be rigid enough to cut aluminum.

Do you need 300mm of Z travel? I would reduce this to 150mm.

the gaps of the two towers are to save weight

You don't need to save weight, you need to make these panels as rigid as possible. make them thicker, with no cutouts.

Your gantry will twist when the spindle is in the center, and all the way down. The 45x45 is too small, and needs to have a full plate behind them.

Where the Z plate gets narrow behind the spindle, it gets weaker. You've made it weakest where it needs to be strongest.

I would not use polyethylene for any parts, they are just not stiff enough.

[TomB]

I mostly agree with Gerry's critique, except you still have to consider weight. Nobody can sidestep F=ma. The weight of a gantry can put significant dynamic load on the steppers and the base guide rails. But you can get stiffness and still have lightening holes. Isolate each proposed part in your mind and envision how it could be bent. Imagine if the gantry cross piece was bolted to concrete at both ends and you put a pry bar through he hole and twisted. The bottom of the frame would flex one way while the top flexed the other way. That same bending action would occur if you imagined a large load hung on your cross member and its the load a cutting action could impose. How could you easily counter those bends? One way, weld a horizontal flange on the top and bottom of the cross piece.

Then imagine your cross piece mounted to the concrete at just the top or bottom of the frame and with cross load on the unmounted edge. Your upper tube would deform to the left or right relative to the lower tube. The solid cross plate Gerry suggests could address that loading but so could putting your cross piece vertical separators in truss style.

When thinking about machines like this one should never forget the advantages of channel sections be they purchased or assembled. Imagine a piece of 1/4" thick steel the same width and length as your cross piece with its ends set vertically in the imaginary concrete. With you hands you would be able to flex that plate quite a bit. But bend the top and bottom edge over to from a channel and your hands would not appear to flex it at all. Where could you use the stiffens of channels and trusses? I'd suggest the sides of your base frame, the vertical risers for the gantry, the gantry cross piece and the spindle support and traveler.

Just thoughts based on considering strong light weight structures in the past.

Tom

[Dytoven]

Well honestly I see fragile too, I think will assist with brackets or make a new design with u-profiles and t-profiles.
This I have to work it a little more.

Where the Z plate gets narrow behind the spindle, it gets weaker.

I forgot to mention that this piece is 20mm, I thought of avoiding collisions with the workpiece.

Do you need 300mm of Z travel?

I have a project that is a replica of a radial aviation engine and thus could make the block in one piece, drill the cilinders in the side face with the 4th axis.

Regarding the choice of motors, drivers etc .. you think is correct? because the structure can always be strengthened but this ..

[ger21]

I forgot to mention that this piece is 20mm, I thought of avoiding collisions with the workpiece.

I'd use something like a "C" channel, and have it wrap around the spindle. This will make it stiffer and less likely to flex.

I would get lower inductance motors which should be rated at 6-7 amps. They'll be capable of much higher speeds.
Don't even think about the motors until the entire design is finished. Requirements may change as the design evolves.

[Dytoven]

Thanks, I'll try to do something more resistant without spending much money.

[Dytoven]

Greetings.
I finished the Y axis, I hope to receive the other parts of the gantry in the next week.

[xrdcarbon]

great project,thanks for sharing,keep going

[Dytoven]

I finally completed the machine and now I'm trying to make it 100%.
I had to replace the plastic parts of the gantry to a iron parts due to vibrations when milling. Have not been eliminated altogether apparently is too high .
Working with wood as a beast and aluminum although I have not tested with appropriate bits also works well.

-My advice for this experience:
Linear guides in Y, X minimum of 20mm, 15mm I used.
Plastic parts with torsion avoid completely.
Aluminium profiles (In my next project I will try to avoid it)
My steppers motors with 4.5 - 8.5 and 12 NM not lose steps.
Steppers drivers plug 240V They are more expensive but does not need power supply and wiring is simpler (at the end they are not as expensive)

Attachment 297590 Attachment 297592 Attachment 297594 Attachment 297596 Attachment 297598 Attachment 297600 Attachment 297602

[NTUU-KPI]

Working with wood as a beast and aluminum although I have not tested with appropriate bits also works well.

How is the machine doing so far? : )

[rshirsagar5]

Got something new topic..will research on it and come to a conclusion.. (y)

[Dytoven]

The machine now has another owner, I could not start any serious project with it. It appears to continue doing the work.