CNC Maxi Pallet For Mill or CNC machine
I needed a better surface to hold parts that would be milled on the CNC with my new spindle.
The spindle was designed to be lower rpm, lower noise, and higher torque so I could use my CNC router to cut aluminum without having cutters running 20K rpm and filling the air with aluminum powder. I also had a lot of 30 3/8 diameter new Niagara 4 flute cutters. ( I know, you should use 2 flute for alu.) This cutter zips through the aluminum and makes chips instead of dust so I like the setup as it is running now. The Maxi Pallet was the second project for the spindle. First we leveled the quarter inch oak ply (butcher board) using the Porter cable router and a 1" two flute router bit. Cut out an area of 30"x30" to make it perfectly flat and then finished it with 3 coats of WBPU clear.
Next step was to clamp the aluminum Pallet blank to the table with the long blue clamp arms and counter sink and drill the 8 holes for the 1/4-20 brass screws that will position and clamp the Pallet to the router table. After the tap holes were drilled through the "butcher board" and the 3/4 thick mdf table underlay I coated the holes with super glue and let them dry over night. Next morning I ran the tap through them and bolted the Maxi Pallet blank to the table. The holes for the 8- 1/4-20 brass screws are counter sunk by about .1 inch so that if I need to cut into the Pallet I won't hit the screws. The 1" by 1" grid holes are drilled for 1/4-20 screws and counter bored .250 deep. I can cut into the Pallet many times before they need to be re-bored and still have .500" depth of threads for the grid holes. You may notice that the center of each quad of holes has a "divit" in the center. These are for any future ad hoc changes that I may need to make to the Pallet for holding odd shaped parts in the future or holes drilled and tapped larger than 1/4-20.
I group my operations for the Pallet by counter boring the 1"x1" grid holes and then drilled them all to .187 and a total depth of .700". When I remove the Pallet from the CNC machine I will finish the holes with a #7 drill for the next process of tapping 225- 1/4-20 holes. The drill press will be used for most of the final drilling and tapping.
Also surfaced the top of the Pallet with the 3/8" Niagara end mill with a 40% over lap and a depth of .005 just to keep everything as flat as possible. This was done after the holes were drilled and counter bored and left very nice edges on all the holes. I don't think I need to champfer them but that can always be done later.
There are two milled channels on the top near the "home side" edges of the Pallet. These are .125 wide, .100 deep and fit my thin parallels to a T. They are very nice for a quick set up that is very close to perfectly square for times that I don't need to use my edge finder or indicator for an exact set up.
The final step was to use the 3/8 Niagara 4 flute end mill to clean up and square up all 4 edges which you can see in the final picture. Finish is quite usable but not perfect. I took the full .740" depth of cut in one pass. Made several passes of .005 and a cleanup of .001 on each edge. After I take it off the CNC machine I will champfer the top and bottom edges.
I uploaded the main DXF file that I used for this project. Many iterations of it were used in CamBam for generating the various milling and drilling operations of this project.
P.S. Maybe now I can start my steam engine!