Makita BUC121 User Manual

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13Sharpening the saw chainCAUTION:• Always remove the battery cartridge and wearsafety gloves when performing work on the sawchain.Fig.20Sharpen the saw chain when:− Mealy sawdust is produced when damp wood iscut;− The chain penetrates the wood with difficulty, evenwhen heavy pressure is applied;− The cutting edge is obviously damaged;− The saw pulls to the left or right in the wood. Thereason for this behaviour is uneven sharpening ofthe saw chain, or damage to one side only.Sharpen the saw chain frequently, but remove onlya little material each time.Two or three strokes with a file are usually sufficient forroutine resharpening. When the saw chain has beenresharpened several times, have it sharpened in aMAKITA specialist repair shop.File and file guiding− Use a special round file (optional accessory) forsaw chains, with a diameter of 4 mm, to sharpenthe chain. Normal round files are not suitable.Fig.21− The file should only engage the material on theforward stroke. Lift the file off the material on thereturn stroke.− Sharpen the shortest cutter first. The length of thiscutter is then the gauge dimension for all othercutters on the saw chain.− Guide the file as shown in the figure.− The file can be guided more easily if a file holder(accessory) is employed. The file holder hasmarkings for the correct sharpening angle of 30 °(align the markings parallel to the saw chain) andlimits the depth of penetration (to 4/5 of the filediameter).Guide the file as shown in the figure.− After sharpening the chain, check the height of thedepth gauge using the chain gauge tool (optionalaccessory).Fig.22− Remove any projecting material, however small,with a special flat file (optional accessory).− Round off the front of the depth gauge again.− Wash away dust and particles from saw chainafter adjusting the height of depth gauge.Cleaning guide barFig.23Chips and sawdust will build up in the guide bar groove,clogging it and impairing oil flow. Always clean out thechips and sawdust when sharpening or replacing thesaw chain.Cleaning the oil filter at the oil discharge holeSmall dust or particles may be built up in the oil filter atthe oil discharge hole during operation.Small dust or particles built up in the oil filter may impairthe oil discharge flow and cause an insufficientlubrication on the whole saw chain.When a poor chain oil delivery occurs at the top ofguide bar, clean the filter as follows.Remove the battery cartridge from the tool.Remove the sprocket cover and saw chain from the tool.(Refer to the section titled " Installing or removing sawchain ".)Fig.24Remove the push nut using a slotted bit screwdriverwith a slender shaft or the like.Fig.25Take the filter out of the chain saw and remove smalldust or particles from it. When the filter is too dirty,replace it with a new one.Insert the battery cartridge into the tool.Fig.26Pull the switch trigger to flow built-up dust or particlesoff the oil discharge hole by discharging chain oil.Remove the battery cartridge from the tool.Fig.27Insert the cleaned oil filter into the oil discharge hole.When the filter is too dirty, replace it with a new one.Fig.28Insert the push nut with its correct side facing up asshown in the figure into the oil discharge hole to securethe filter. When the filter cannot be secured with adisfigured push nut, replace the push nut with a newone.Reinstall the sprocket cover and saw chain on the tool.Replacing the sprocketBefore fitting a new saw chain, check the condition ofthe sprocket.Fig.29CAUTION:• A worn sprocket will damage a new saw chain.Have the sprocket replaced in this case. Thesprocket need to be installed so that it alwaysfaces as shown in the figure.Fig.30Always fit a new locking ring when replacing thesprocket.

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