NordicCNC's build log

[joe.ninety]

Those block are used to increase the gantry clearance. I want to build machine out of aluminium profiles and the 200x80 profile for the Y-axis sides are not high enough.

Ok, in that context I understand. It's just in most designs I've seen there is simply a gap there... The desired height achieved by where on the gantry sides you bolt the cross-section (the main bit of profile that forms the gantry).
So in your design, the gantry cross section is supported by being both bolted to the side plates and also by sitting on other pieces of extrusion? Are the blocks underneath connected to the cross-section or does the cross-section simply sit atop them?

Cheers

[NordicCnc]

Ok, in that context I understand. It's just in most designs I've seen there is simply a gap there... The desired height achieved by where on the gantry sides you bolt the cross-section (the main bit of profile that forms the gantry).
So in your design, the gantry cross section is supported by being both bolted to the side plates and also by sitting on other pieces of extrusion? Are the blocks underneath connected to the cross-section or does the cross-section simply sit atop them?

Cheers

Yes, L-shape bolted together to the gantry sides. Screw clearance holes in the lower profile, threading into t-nuts in the upper profile. I also intend to use aluminium plates and shim them in the t-slot, to act as guides/stopper so that the gantry profiles doesn't move. The blocks underneath the L-shape also have holes and mounts to the lower profile.

Actually I am extremely glad that you commented on the design. It made me realize that I could further increase the stiffness while not compromising gantry clearance significantly!

I've now removed the 60mm high profiles from the gantry sides. Instead I've replaced the 20mm thick blocks underneath, with 40mm blocks. These are going to be machined so that the Z-axis can pass above the blocks. This effectively decreased height the gantry sides by 40mm, less parts, increase simplicity & accuracy while making the gantry stiffer.



However this means that I need to modify the table to compensate for the lost 40mm clearance.

In the current base frame, I've used 120x80 profiles bolted into the sides, consisting of 200x80 profiles. I have 2 alternatives I think:
1. Replace the 120x80 with 120x60 to gain 20mm clearance. Now I've only lost 20mm clearance.
2. Move the 120x80 underneath the 200x80 profiles (+40mm clearance) and bolt from the bottom. Add 20mm item profiles (wide version) as a "T-slot bed" (+/-0mm clearance).

I think I will go with option 2, which will make the bed stiffer also! The budget allows for it anyway.