34 BULLETIN 118^ U. S. DEPARTMENT OF AGEICULTURE. 



moTement endwise when the mandrel is running. The mandrel must 

 fill the eye of the saw, but enter freely. Alwaj^s 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. 



Af t«r 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 mider 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 



