Hi! I have started my first DIY CNC project.

General CNC CNC Routers
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1

Hi!
I have started my first DIY CNC project.
Design done in Fusion 360
I have based the design on parts I got from a friend.
25mm Rexroth slides and blocks
2 x 500mm (Z)
2 x 520mm (X)
2 x 700mm (Y)

Front and rear alu profiles = 40x120mm
The sides where the 700mm Rexroth are installed = 20x70mm solid alu
The two Rexroth slides on X are mounted on 2 x 45x90 profiles
The “Legs” = 45x90
Most of the alu parts on Z = 10mm alu

My plan is to use 1605 Ballscrews on all axes + Nema23 + a 1.5Kw spindle + a Toshiba 1.5Kw VFD

Have not decided what controller/drivers to use.

I have some work to do before the 3D model is ready . Alu profiles between the Y sides to make it stronger, motor mounts…

Work area 30-40cm x 50-60cmx 20-25cm

Hope to get a CNC that can handle alu, wood… fine

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Controling software?

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I gues I`ll use MACH3

4

Isn’t a 1.5 KW spindel a bit over sized for your need ?

5

I do not know - a friend told me to use a 1.5KW - but I have not decided/ordered any electronics/steppers or spindle yet. I`ll have to spend some time trying to find the best combinations…
But I have the Toshiba 1.5Kw VFD, so I can use max 1.5Kw spindle.

6

I would up that to a 2.2kw spindle and an ER20 collet. Upgrading after a build is costly.

7

The 25mm Rexroth slides/blocks are rather solid :slight_smile:
Compared with an 0.5L can
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8

What oz steppers would you use on a setup like this?

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Nema 23 is what i use. In a woops moment i bent a 5/16’’ hold down bolt to a 45deg angle :frowning:

10

Looks like a nice setup. I’ll suggest to go for a network or usb interface between mach 3 and controller. I use a networked smoothstepper and is very happy with that. I also use 7A/80V driver for each stepper, but that is really overkill. You could do with the compact 4 output gecko g540 which I think is rated to 4.5A/50V.

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@Oyvind_Amundsen
What steppers you use depends on how fast you want to go. There are calculators online that can figure out what torque you need based on what lead screws you use. Here’s one http://www.orientalmotor.com/support/motor-sizing.html From there pick ball/lead screw.

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I find it a bit dificult to find the correct motor… setup. Some tell me to use a large 425 oz steppers to get the best performance, other tell me to use low cost 125 oz motors but 36V power to get fast performance.
Some tell me to use 1Kw spindle other 2.5Kw…
I know you get what you pay for, but I also know that you do not allways get the best performance by buying the most expensive…

Anyone that have a setup close to mine that can tell what motors… have been used and if that is ok or not?

I think I can get a stable CNC using the 25mm Rexroth + the frame profiles… and I hope to be able to cut alu with an ok quality…

13

I may replace the two 20x70x900 solid alu parts on the sides with 2 40x80x900 Bosh Rexroth alu profiles - this makes the installation easier

14

@Oyvind_Amundsen
My advise to you is try to design your machine so you do not have to exceed 1,000 RPM on your lead screws to travel the speed you want to go. Because over 1,000 RPM then things begin to get dicier as far as the mechanics go. But under 1,000 RPM it just works. You could use duck tape as a motor coupler then, and it’d still work. It will be easier on the software side not having to drive motors so fast too.

The critical factor in the end is the pitch of your lead screws. You want low pitch. Something around 2 threads per inch would net you great performance. It would make your life so much easier in so many ways. Avoid the pain, disappointment, and heartache of high pitch lead screws. It is nothing you ever want to experience for yourself, firsthand.

A 2 TPI lead screw spun at 1,000 RPM travels at 500 Inches Per Minute. So you really only have to go half that speed, and you’re still moving right along.

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In this model I have replaced the frame sides with 40x80 Bosh profiles + inserted some 20x40 profiles between them. I consider using 40x40 profile in each corner to make the corner stronger + act as legs. The Y-screw in this model is only a test.
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I consider using legs like this (12mm plexi)
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Have designed legs (12mm plexi) + have made the base frme more solid.

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