Civil Engineering Reference
In-Depth Information
Fig. 2.6. This Tom Senior table has a couple of machining marks where the cutter
has pulled down. Slight marks like this are acceptable on an otherwise good-condi-
tion milling machine, but if there are a lot of cutter or hammer marks on the table it
may mean the machine has not been carefully looked after.
Which collet system?
An important decision needs to be taken about the collet system used in the
spindle. The smaller mills will have a 2 Morse taper or possible a 3 Morse
taper spindle. A large turret milling machine would be much more likely to
have an R8 taper. It seems to be easier to get second-hand 2 Morse taper
collet holders than their 3 Morse taper equivalent. Better still would be to get
the R8 version if you can. R8 collets are much more substantial than 2 or 3
Morse taper shank cutters and, as they are often used in industry, more vari-
ations of R8 holders are available. You can even get a quick change R8 hold-
er which is ideal for drilling holes as you can centre drill with one tool holder,
drill with another and ream with a third. The holders are very quick to change;
the holders only take a few seconds to swap over.
