Raglan Milling Machine
The Raglan Mill differs from most small milling machines
in that not only does it have Raglan's Mechanical Variable Speed Drive, it also has the
main body formed as a one piece alloy casting.
The table rises and falls on a cast iron slide controlled
by a large diameter acme thread feedscrew which is protected by a tube inside the cabinet.
The cabinet seems to have been supplied as standard with each mill as the feedscrew
precludes the mill being mounted on a conventional bench top.
| Specification
Table dimensions .................. 440 x 140 mm
Table travel ( long ) ............... 300 mm
Table travel ( cross ) ............. 105 mm.
Knee travel ............................. 185 mm
Throat depth to column ....... 108 mm
Spindle taper .......................... 2 MT
Draw bar thread ..................... 3/8 B.S.W.
Cross slide feedscrew .............. 2.5 mm pitch
Cross slide dial graduations ... 50 divs of 0.05mm
Table feedscrew ....................... 2.5 mm pitch
Table slide dial graduations ... 50 divs of 0.05mm
Knee feedscrew ........................ 2.5 mm pitch
Knee dial graduations ............. 50 divs of 0.025mm
Spindle speeds ......................... 380 - 2400 RPM
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| A worthwhile modification I carried out to my
mill was the fitting of a very simple drive system to give power feed to the table
leadscrew. A search through various scrap bins at work came up with a 12V motor with a
gearbox attached which gives 90RPM. From the same source I found some small toothed belt
gearwheels. They give a reduction of about 3:1 and the larger one had the bore machined
out until it was a nice fit on the outside of the table handwheel. On my mill the
handwheel had the area where I fitted the large wheel machine nice and smooth but as I
have seen only one other Raglan mill I'm not sure if this is a standard feature. Once the large wheel had been super glued to the handle I now had
to figure out how to fit a clutch system to the motor. My solution was to fit a brass bush
to the smaller wheel, fit a shouldered shaft to the motor output shaft, and thread the end
of the new shaft 2 B.A. A knurled knob threaded 2B.A. fitted on the shaft gives a very
simple clutch - tighten it to give motor drive, slacken it to give manual feed. The knob
can be seen in its disengaged mode in the photo alongside. I have exaggerated the movement
required to show the knob and shaft more clearly
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| Now the drive system had been worked out all
that remained was to fit the motor to the mill. Here I used an alloy plate I had lying
about. A "U" was cut out to clear the table end casting for the handwheel
bearing and the plate fitted to the mill with the original screws. These screws were still
long enough to give an adequate fixing for the end casting.
The motor position was determined by fitting the
belt in place around both gears and moving the motor until the belt tension was right. The
motor screw holes were marked and drilled. The whole system was then tested and seemed to
work properly. Using an old 12V model railway controller gives both direction and speed
control and although the system is simple it does work Sometimes on a heavy cut the screw
tends to slacken off but this is a good safety feature and I think the effort put in to
making the drive was very worthwhile. To sum it up; Crude - but effective!
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If you look closely at the bench to the
right of the mill you can see the cylinder and wheel castings for a "Sweet Pea"
locomotive which I had just unpacked.
