Stell frame cnc 1500X1000. Adjustable table your opinion please

[Boyan Silyavski]

Hi Vagelis,
I answered some of your questions in my build thread. here is what i think for the other ones.

I I wont use a movable cutting surface as I first had in mind. The cutting surface and the clamping system will look like this.



On the 80X80X4 steel tubes I will weld 80X40X3 vertical pieces and between them 40X40 tslot aluminum profile. On the 80X40X3 steel tube, 19mm plywood will be bolted. If there is any comment I will be glad to hear it.

Your solution seems very nice, man i like it. May be will implement it in my next build. But the plywood thing i don't like. Will constantly need resurfacing if you make precision stuff.
better would be some scrap plastic sheets from doors or whatever found at the Junk yard. And on top-sacrificial layer of expanded PVC plastic sheet. Quite cheap.

Now regards the gantry it will be made from 2 80X80X4 tubes(in the middle ) and 2 120X60X4 tubes (up and down) welded together like this. At the back side of the gantry all the tubes wont be in the same plane. The 80X80 tubes will exceed 2cm to make space for the ball nut mount flange.



The ganty will be welded and then bolted straight to the hiwin carriages ( after I apply epoxy at the bottom side of the gantry ).


And now I come with my questions.
The clearance (after Deans suggestion ) from the lower point of Z to the cutting surface is 180mm. The travel of Z is nearly 130mm. When z axis is at its lowest point the situation is this







That means 6mm from spindle choke to the cutting surface.



When z axis is at its higher point the situation is this


That means 136mm from spindle choke to the cutting surface.


Is that Ok?This is very critical for the machine construction as any mistake here will need frame reconstruction. Generally is there rule about what is the distance from the choke to the cutting surface when Z is at its lower point.?

What spindle /KW?/ will you be using at the end? That make protruding things longer or shorter.
Also have in mind usual 1/8 bit is 10-30mm long, usual 1/4 bit is 20-40mm long, the piece that is not in the collet i mean.

Finally i want to ask about resonane. Is it better to use these red plates

This is best i believe:

Or it is better to use a 80X80 tube to connect vertialy left upper side of the frame with the rights upper side of the frame



Thanks for your time and i will be glad to hear any suggestion

Vagelis

What about doing longer than your table stuff?