In version 2 of the CNC Construction Set, I decided to go with a more traditional gantry.

While the original top down gantry was very solid, it was not well suited for a machine this small.  I was canstantly running into height issues.

 

The Rails

I'm using 20mm x 300mm supported rails for the X axis.

They are attached to the gantry just like the Y rails were attached to the base using 1" steel angle.

Both the steel angle and the rails are held in place with 10-32 screws and T-nuts.

 

I attache the Y angle flush with one side of the gantry.

I then slide on the rails and drill out the hole into the steel angle using the rail holes as a guide.

 

 

Gantry Riser Blocks

I needed a way to securely mount the gantry to the Y carriage extrusion.  I tried all kinds of angle brackets but they were are to keep the gantry aligned.

I came up with these little riser blocks.

They are just under 2" tall.  My blocks are acctually 4 pieces of 1/2" stock stacked one on top of the other.

The bottom piece are counter sunk to allow the bolt heads to sit below the surface when attached to the gantry.

The three outside holes are used to attach to the Y carriage.

Note that later I will also install some end plates that will also act as motor and bearing mounts.

 

Gantry Assembly

To attach the riser blocks, I first connect the four pieces by using bolts in the three outside holes.

The blocks are then attached to the bottom of the gantry using 4, 1/4-20 x 2" bolts and T-nuts.

Afterwards, the three outside bolts are removed.

 

Attaching the Gantry to the Y carriages

The gantry is attached to the Y carriage using three 1/4-20 x 2-1/2" carriage bolts on each side as shown here.

The bolts are only finger tight until I square things up, then are fully tightened the rest of the way.

 

Conclusion

That's it, Its time for use to start adding the drive components.  Notice how I have added some extra carriage bolts to the gantry.  Once the gantry braces are in place, I wont be able to add them later.