Sturdy and Fast all Steel CNC , my first build

[Gytis]

in my opinion with so wide Z axis plates you just wasting a lot of material and travel in Y axis direction.,
with 20mm profiled rails you can do Z axis on 160mm wide plate, and extend travel in Y direction, or just save matirial in all you built.

[Boyan Silyavski]

in my opinion with so wide Z axis plates you just wasting a lot of material and travel in Y axis direction.,
with 20mm profiled rails you can do Z axis on 160mm wide plate, and extend travel in Y direction, or just save matirial in all you built.

Hi,
you are quite right. However let me explain please. 10cm more of rail on both sides+10cm more of screw+10cm more of steel profile=no more than 60 euro, which is irrelevant in this build. If we look into KG , they are 5-6 kg more on the gantry
However an ATC is very expensive. And is quite necessary for 3D jobs. Should the need arise to upgrade, for the mere cost of 2 more short supported rails and bearings+another chinese spindle i can mount double Z axis with minor modifications and most importantly without compromising the work dimensions. One spindle will rough the other will detail and finish.
I mean, there also some other points of the design that are done with some things in mind. Its not a general hobby machine.

[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?