Next step is the assembly of the ball screw spindles for the X-ax. They will be mounted in the standers which together with the table top forms the basic frame of the machine. This is done only to see if all fits perfectly, after the gantry is put in place on he basic frame they will finally be assembled.
At the top the completely assembled stander. Below the parts needed: left and right frame, 2 ball screws at the end of the spindle. At the motor side we have 1 ball bearing, the pulley, ax coupler a distance part to mount the motor on the frame and the motor itself with an adapter to fit a Nema 17 to a Nema 23. Because I'm using a Nema 17 motor, as is used for the popular reprap 3d printers, I also had to fit an ax adapter on the stepper motor from 5 to 10 mm to fit the ax coupling.
The ball bearings are fit in between metal parts who are secured by screws and tighten to the frame. A simple construction but effective solution.
For the table top you have the choice of different solutions: an aluminum tabletop with slots, or a MDF tabletop. I decided for the last option and use a 22 mm MDF plate, 600 x 385 mm.
The MDF was prepared with polyurethane paint to lock the surface for any liquids so you use cooling liquids in case you want mill aluminium or bras.
The assembly of the table top with the side frames is easy to do: Clamp one side to the frame and drill the holes in the table top. The frame contains slits to fit the screw and you can adjust the frames, so they are parallel to each other. I measured the distance between the left and right frame so they were parallel and 3 screws were mounted at each side to hold the table top. Don't tighten them so we can move them aside if needed if we mount the gantry to the basic frame.
Now comes a tricky part: we have to mount the portal on the basic frame.
The machine on the workbench, note that the gantry was mounted allready.
First we have to take care that the X-ax spindles are removed. Then turn the basic frame upside down on the workbench supported by two wooden beams, see picture. The ball bearing support on the top the gantry is removed so the ball bearings of the bottom side can slide over the underside of the frame. Next step is bring the gantry over the feet of the x-ax frame and let the ball bearings run over the frame. If needed you can adjust the x-frames to fit the width of the gantry and try to shift the gantry over the support from one to the other side. It runs smoothly and I tighten the screws to the table top. Now the ball bearings at the upper sliders are mounted to the gantry. Again I tried the movement of the gantry to find out if it still was running smoothly. It did
. If it doesn't you have to adjust the width of the table.
The result of previous steps: it is starting to look like a CNC machine!
Now it is time to mount the ball screws for the x-ax, the pulley for the synchronization of the x-axes and fit the t-nuts in the slots of the gantry. This synchronization is needed in case that one motor looses steps or doesn't run at all. It prevents the gantry from distortion on the x-ax.
Mounting the t-nuts into the lower part of the gantry went easy, all fit well. The tooth belt and pulley's have to be assembled before the ball bearing at the motor end is fitted into its holder. Otherwise you don't have any space to install the belt. In this step I also took care of positions of the hexagonal screw in the pulleys so that they are reachable at the same time, to tighten or loose.
The ball screws were fit in the holder and tighten to the frame. Job done so far for the x-ax.
here you can see the ball bearing of the x-ax at the motor side, the tooth belt and the protective shield for the tooth belt.
If the motors are attached to the x-axes and the pulleys are tighten to the axes we mount the protective shield to the frame.
A ball bearing will be mounted in the protective shield to set the tension of the tooth belt.
Next step is to mount the Z-ax on the gantry and the y-ax spindle.
To mount the z-ax support on the gantry I had to remove the green HDPE slider blocks of the bottom. In these blocks 2 ball bearings are mounted who slide over the Y-rails the z-ax was already completely assembled in an earlier step. So we position the z-ax support on the y-rails. Next step is remounting the ball bearings on the bottom side and adjust the tolerance on the y-rails by gently tightening the 4 hexagonal screws in the upper and bottom slider blocks:
I tried to slide the z-ax support over the y-ax and this runs smoothly by hand.
Second step to do is mounting the y-ax spindle and t-nut.
This is easy to do, everything is open for assembly and I could easily put the ball screw in place and fit the t-nut.
This picture shows the fully assembled spindle for the y-ax. You can also see that the motor coupler is mounted. The ax-coupler is 30 mm long and has an inner diameter of 10 mm to fit the motor and spindle. Due to the use of Nema 17 motors I needed to fit a 5 to 10 mm adapter on the motor ax.
So that is all to do with the mechanics so far. Next thing to do is the mounting of the motors and test run the machine!
