34 BULLETIN 718, TJ. S. DEPARTMENT OF AGBICULTUEE. 
movement endwise when the mandrel is running. The mandrel must 
fill the eye of the saw, but enter freely. Always use a wrench and 
never a hammer on nut of arbor. The pins in the collar must have 
a fair bearing. Sometimes when driving them in a burr is thrown up. 
If not carefully filed off this tends to throw the saw over to one side. 
After the mill is set up and before starting, move the carriage 
slowly by means of the sliding paper friction. When everything is 
in good order this friction can be turned easily by hand and the car- 
riage moved in either direction. If it can not be easily moved, ex- 
amine the gear and pinion to see that they do not mesh too deep or 
bind against the flanges; see that the rack pinions do not mesh too 
deeply in the rack under the carriage; also examine the set col- 
lars on the track axles to see whether they are too tight and need 
slight loosening. The carriage will run hard when the track is 
not level and straight. Give the saw from one-eighth to one-fourth 
inch lead in 20 feet, according to the condition of the saw and charac- 
ter of the lumber to be made. More or less lead is given the saw 
by means of set screws on either side of the main mandrel bearing. 
Do not try to lead the saw by pulling it over with the guide. The 
wood pins in a saw guide clear the bottom of the saw teeth by an inch. 
A good way to give proper lead to a saw is to turn the rear head 
block up opposite the center of the saw, and fasten a stick or board 
on the head block so that the end of it is set one-eighth inch from the 
saw. Then run the carriage back until this stick is 20 feet from the 
center of the saw. Then stretch a line from the end of the stick 
along the face of the saw, so that it touches the saw on both edges. 
If it does not touch the saw on both edges, adjust the main mandrel 
box by the set screws on each side of it until it does. You then have 
one-eighth inch lead in 20 feet. This is called slewing the mandrel 
to regulate the lead. The same result may be obtained by sighting 
over the saw and fixing the saw plane for a radius of 10 feet. This 
may be done by placing two shafts vertically into the ground 10 feet 
from the saw center, behind and in front of the saw. Then a hori- 
zontal stick is fastened to a head block so as to just touch the for- 
ward staff. Then the carriage is gigged backward to the other verti- 
cal staff, where the horizontal stick must lack exactly one-eighth of 
an inch from touching. The belt holes or set screws in the boxes of 
most mandrels are slotted, and it is only necessary to loosen the set 
screws and move the boxes one way or the other by a few light blows 
of a hammer in order to get the proper lead. 
OPERATING THE MILL. 
First see that everything has been set up according to directions 
and all nuts are tight. Then with kerosene or benzine carefully 
clean the turned surfaces of the friction disk and the sliding friction 
