Sturdy and Fast all Steel CNC , my first build

[Boyan Silyavski]

Hi there,

I am on the way of my 1rst real build. The idea is to be fast and sturdy. I am building it for a friend by order. Its a smaller variant of a sturdy machine i designed not long ago for my self which i would build after that build, which will serve also to figure some points of the process.

I have a lot of questions and will appreciate any help with this one, as i would like to make it really right.

From my part, once finished, i will provide the Sketchup plans for free here, so anybody can use them if wished so.

Some of the design points:

1. All steel soldered construction. Overbuild for stiffness, avoiding weak elements in the design.
2. Money is not an issue for the frame or the length of the supported rails, so i am not going to go cheap to save 10cm of rail or steel profile.
3.This machine is for continuous 3d jobs routing plastic or composite epoxy based materials so a desired stable routing speed of 300ipm is the goal
4. Usual job size would be 800x400x160, hence that commands the gantry clearance and z design
5. 3d continuous very detailed jobs, > 24h sometimes, made me choose a low power spindle like the 0.8kw water cooled one. Electricity cost is an issue here

So i am at the point of finishing the design, still waiting for some details on the profiles. Already started purchasing the components. I hope in 3 months it should be making dust

Here are some pictures of the design, still not finished:



Profiles used 180x80x4mm
gecko 540
Nema 23 low inductance motors , CNC routerparts Pro Rack and pinion drives 1:3, mod 1 rails, Hiwin HG 20 rails with long wide bearing blocks on all axis,
All plates are 10mm thick mild steel,

The doubts:

1. Now before i finish the design and order the profiles and plates , i wonder about the gantry weight. My design is 1000mm 180x80x4 profile with soldered over it at all sides 10mm steel plates. Basically the profile weight will be around 15kg ,reinforcing it will be another 50 kg+ the side plates another 10 + 2 motors and drives + Z another 12-15kg=more or less 100 kg. I am waiting for an advice from CNC routerparts about the gantry weight. If it heavy i can hollow some holes in the reinforcing plates to bring it to the desired weight , however i would like to reinforce it more than leave bare profile.

2.Another point here is that i am not sure if i can bolt to 4mm profile directly threading it or should be 10mm plates below RP rails, Hiwin rails, as i designed it

Notes:
- the table would sit on 2 more rails same of similar size soldered. This should raise it for the cable guides and stiffen it, to avoid twisting . I am contemplating making a case there and all electronics mounted inside the base of the machine

What do you think about the design?