Harrison M250 - Thread-cutting

(Al
METRIC THREADS on METRIC LEADSCREW MACHINES
or
ENGLISH THREADS on ENGLISH LEADSCREW MACHINES
For these threads it is recommended that the "thread indicator
dial" be used - this allows the leadscrew nuts to be disengaged
at the end
of each screwcutting pass, provided that they are
re -engaged in accordance with the chart mounted on the front
face of the dial unit.
METRIC LEADSCREW MACHINES
OIIIDmm
(METRIC THREADS ONLY)
•
•
The chart shows: -
0.25 20
14
1.4
21
0.3
20
14
1.5 20
0.35
21
135
1.76
21
in column 1.
mm pitch to be cut.
0.4
20
14
2
20
0.5 20
14
2.5 20
in column 2. !• l
The requisite gear of the double pinio n
0.6
20
14
3 20
should be arranged to mesh with the
0.7
21
135
3.5
21
0.75 20
14
4 20
leadscrew.
0.8
20
14
5 20
1
20
14
6 20
1.2 20
14
7 21
in column 3.
The dial numbers at which the leadscrew
1.25
20
14
8
20
nuts may be engaged.
OIUDins
ENGLISH LEAOSCREW MACHINES .
4 1-6
11 1-6 28
4½ 135
12 1 -6
30
(ENGLISH TH READS ONLY)
5 1-6
14 1-6 32
5½
135
15 1-6 36
The chart shows: -
6 1-6
16 1-6 38
6½
135 18 1-6
40.
in column 1.
T.P.I. to be cut.
7 1-6
19
1-6 44
7½
135
20 1-6 48
in column 2.
Dial numbers
at which the leadscrew nuts
8 1-6
22 1-6 52
may be engaged.
9
1-6
24
1-6 54
9½ 135
26 1-6
56
10 1-6
27 1-6
60
(B) ENGLISH THREAD S on METRIC LEADSCREW MACHINE S
or
METRIC THREADS on ENGLISH LEADSCREW MACHINES
or
ALL THREADS ON MACHINES NOT FITTED WITH THREAD INDICATOR
For these threads the leadscrew nuts are kept engaged thro u ghout the cutting of any one thread.
This involves reversing
the whole drive by means of the reverse switch (2) at each end of the
screwcutting pass whilst at the same time relieving or increasing the cut as required.
(Threa
ds 'A' may also be cut by this method).
( Thread - cutting J
14
135
14
135
14
14
14
135
14
14
14
135
1
1-6
1-6
1-6
1-6
1-6
1-6
1-6
1-6
1-6
1-6
1-6
1-6