The CNC mini-mill uses an R8 collet based tool holding system which consists of a vertical rod that draws a collet up into the spindle. This collet has a taper (the R8 designation) that matches the spindle and is pulled tight by the draw bar.
[[File:MiniMillSpindle.jpg|left]][[File:MiniMillChuck.jpg|right]]
”I will label these images shortly. For now, here’s a quick description for each of the relevant images:”
Left Picture (top and body of spindle column):
– Very top of picture is the draw bar nut
– Below this hex bolt is the drive pulley with
two settings, a low and high gear
– Then the spindle column extends to the bottom
of the image
– The R8 collet is just barely visible with the
top of a drill chuck inserted in it
Right Picture (lower portion of spindle column)
– Just below the red metal box is the lower
portion of the spindle column
– The first step in diameter is the small visible
portion of the collet
– This collet has a 3-jaw drill chuck loaded
– The drill chuck has a sanding flap wheel loaded
Available collets and tools
A variety of R8 collets are in a small metal rack on the wall below the cabinet. Carefully pick the appropriate collet for your tool’s shank. Do not use drills or end-mills greater than 1/2″ in diameter.
Procedure for tool change
- Raise head
- Lock spindle from turning by using a small rod inserted in the hole in front of the column. Don’t use a drill bit or end mill for this.
- Be ready to catch tool as you loosen, it should NOT hit the table or fall to the floor
- Loosen draw bar nut – DO NOT leave wrench on top of spindle 3/4″ nut
- Insert new tool into collet
- push collet into spindle column
- Tighten draw bar by hand
- Use wrench to tighten draw bar – Monkey tight, NOT gorilla tight
- Place the wrench in a safe location – DO NOT leave wrench on top of spindle