Sturdy and Fast all Steel CNC , my first build

[Boyan Silyavski]

After some tinkering i woke up that i am not making the CNC for myself and that i am overbuilding it too much. And overthinking it about the eventual future. Went to the local metal shop and checked the profiles. There was 140x80 profile that seemed quite good, so instead of searching for the 180x80, i sat down and redesigned everything, it was fast though taking away things. Changed the profile sizes, took away the reinforcing plates on the gantry, though i left place if i later decide there are vibrations. redesigned the Z narrower and so on. The benefit is that the profile enters the magic 6m number, as they sell it by the 6m.

So following your advice i finished with smaller and lighter gantry, like 30kg, shortened it and now everything is exactly as it should be, no over sized stuff in my opinion. 1000x400x170mm working area, as wanted by the guy.
What do you think?

[JAZZCNC]

What do you think?

Couple of things.!! . . .The Z axis is wrong and your weakening not making stronger.? The spindle hanging down like that in conjunction with rail/bearing setup is a constant length lever at any Z extension.
It won't allow any better clearance when cutting has the Tool length mostly dictates this and your spindle support plate will still catch just like the bottom of Z axis would.
Much better option IMO would be to flip the rail and bearing setup so you have a variable length lever when extended giving much better strength and just build a sturdy spindle bracket that allows percentage of the spindle body to extend below Z axis plate.
This extension along with tool length will be give enough clearance for most 3D work. If the guy needs more clearance then better to buy longer tool and cut slower than compromise the machine in all other areas.!!

With the proximity sensors (Or limit switches) because of the small gaps required to work correctly then I wouldn't put them at the ends were they will get run into if crashed. Position them so they get passed by or over this way nothing gets crushed.

[Boyan Silyavski]

Couple of things.!! . . .The Z axis is wrong and your weakening not making stronger.? The spindle hanging down like that in conjunction with rail/bearing setup is a constant length lever at any Z extension.
It won't allow any better clearance when cutting has the Tool length mostly dictates this and your spindle support plate will still catch just like the bottom of Z axis would.
Much better option IMO would be to flip the rail and bearing setup so you have a variable length lever when extended giving much better strength and just build a sturdy spindle bracket that allows percentage of the spindle body to extend below Z axis plate.
This extension along with tool length will be give enough clearance for most 3D work. If the guy needs more clearance then better to buy longer tool and cut slower than compromise the machine in all other areas.!!

With the proximity sensors (Or limit switches) because of the small gaps required to work correctly then I wouldn't put them at the ends were they will get run into if crashed. Position them so they get passed by or over this way nothing gets crushed.

Thanks guys for the input. I seem to have been missing the obvious.

I redesigned it following the advice. Now things seem better / to me at least :-) / . What about the result? By the way i have bought already the spindle brackets/2/ . I liked the design because can fix them on a guiding plate so if i have to move them its easy to align them.

So now the rails move and the bearing blocks stay at optimal position. If he wants to cut thin material he can fix a 10cm high MDB surfaced table made from a couple of boards glued together so there will be no need to change spindle position at all. And take it off when he likes to do deep jobs.

Can i cut the motor shaft from the back side? Is it enough place for the cables of the motor? See picture. I need to further redesign it a bit otherwise i have to solder it with the motor in place , he he he. Ok, i wouldnt do it so. Just joking.

[JAZZCNC]

If this guy is wanting mainly to do 3D work then I'd also look to make the Front Z axis plate the narrowest and lightest you can make it.
Keep the Y axis bearing spacing wide but bring the Z rails in the most you can get away with and have light narrow front plate.

3D requires fast directional changes and high acceleration so anything to help here will speed up the job.!

Regards the motor access you have enough width and height in that plate to cut an access hole for motor and still not lose any strength, will cut weight too.! . . .Win win.!!

[Boyan Silyavski]

If this guy is wanting mainly to do 3D work then I'd also look to make the Front Z axis plate the narrowest and lightest you can make it.
Keep the Y axis bearing spacing wide but bring the Z rails in the most you can get away with and have light narrow front plate.

3D requires fast directional changes and high acceleration so anything to help here will speed up the job.!

Regards the motor access you have enough width and height in that plate to cut an access hole for motor and still not lose any strength, will cut weight too.! . . .Win win.!!

Thanks Dean,

I finished with a 130mm wide fron z plate. It should be enough. I dont believe it can compromise anything, as in my router i have exactly this plate using only one slide with the wide flat rail+ 2 bearing blocks and is ok strong. However i would not like do it like this in this build, cause later i have to play a lot with hole placements and finding screws that could fit under the plate and then aligning it. As i did with mine.

I have another question. When laser cutting, should i do exact holes that hold the plates to the bearing blocks or i should elongate them. Cause how do i know that the rotating nut will fit exactly at that place. Otherwise i will loose some millimeters from the travel. How it is done?

[Boyan Silyavski]

Hi there,
today worked more on the drawings, mostly lightening things where possible without compromising strength. Starts to look like a cheese. However all holes will be closed with bolted light plastic plates so at the end will be quite dustproof even if its not seen on the drawing.

Received the spindle mount brackets. And made an important decision.
Well the 2 brackets are very nice, especially for the money, but... not the same as on the sellers picture. In fact they are so robust that i will use only one. man, they are big.

The important decision is that until i don't have the ball screws and the Hiwin rails at hand Not to order and laser cut pieces and not do any soldering at all. My design heavily depends on the exact hole placement and the laser cut pieces, because i have at hand a very cheap laser service, so cheap that it would be more costly to than to draw by myself and drill the holes at home from junk steel plate with my flimsy drill. And as i don't have a mill at hand and the service here in Spain is very expensive, laser cut is the way for me. Which gives me quite a freedom in my design.

I need some help with the following because i have no idea at all:

1. Proximity sensors

Ok, i designed a plates for them, there is like 12mmm possibility for adjustment. Will solder the plates /10mm thick/ directly on their places. But..

-How far from the actual x,y,z hard stop ???? / x = moves the z , y=moves the gantry/
-any example of Z proximity switch placement? No idea still how and where to fix them. Of importance is the diode to be visible.
-Homing of the z is up, yes?

2. Drag Cable Chain
The thing still missing from the drawings.

-Judging from my current setup/2 small chains one next to another/ i need 20x50 internal drag cable chain so cooling hoses and cables can pass freely. But... i can not find anywhere what is the radius. Grrrrrrrrr. If somebody has a similar chain and point me to the radius i would be very grateful

3. Motor cables
can somebody point me to per/m good motor cable, shielded, here in EU?


It seems also for the purpose of the chain, i have to lift the machine. Another thing is that i still have not found a good case for the electronics. It has to look really good.
I am starting to thing about raising everything and boxing the electronics inside the machine. I have my small machine at home like this, so i know the all bad points and will avoid them. Believe me there are many. Like when drivers heating from inside, heats my aluminum table that heats the hot glue i use for fixing stuff and everything flows in the air some times when routing... Of course knowing them i can avoid them. By the way vibrations to the components was only once a problem and it revealed a cold weld on the BOB transformer. Nothing more...

[Boyan Silyavski]

Waiting for the square rails and ballscrews purchace, made me play again with the design. Decided to stuff all the electronics inside the body. Due to various reasons like avoiding
10 Neutric connectors sticking out at the back, cables, enclosure and so on. mainly because i live at the seaside so connections always give me trouble and i have to glue my connections with hot glue.

Decided also to make the structure from 60x60 4mm at the important places and 3mm at the no so important. But what ever i did i couldn't figure placing diagonals so i finished with rigid square design and 100kg structure. more or less 18meters of steel. I think i overbuild it a bit.

Another decision was to make the bed deep enough so there is no need to change spindle position. Instead a wood bed would be fitted so the spindle works at normal position and only when necessary to remove the wood bed, not move the bed of the machine or anything.

Hope that structure is strong enough, cause tomorrow will order the steel.



If somebody sees something wrong, please tell me until is time, he he.