Makita D-73754 Round File Bit for Sharpening Saw Chains, 4.5 mm, 1/4

Makita D-73754 Round File Bit for Sharpening Saw Chains, 4.5 mm, 1/4" Hex Shank

Makita D-73754 is a round file bit with a diameter of 4.5 mm (11/64") and a 1/4" hex shank. It goes into a cordless drill driver, an impact driver or a drill and sharpens the cutters of a saw chain right on the guide bar: the machine turns the file instead of your hand pushing it. The working part has a diamond coating. Makita lists it for 3/8" LP chains and gives the 4.5 mm diameter explicitly for its own 90PX chains (1.1 mm gauge). The filing angle is 30°. The pack contains 1 piece.

The 1/4" in the name is the shank, not the chain pitch

This is where a wrong purchase is easy to make. The 1/4" marking refers to the hex shank (6.35 mm) - the same standard that screwdriver bits are made to. It does not mean the file is meant for 1/4" pitch chains. The size that has to match the chain is the file diameter - 4.5 mm. It is engraved on the hex as "4.5mm (11/64")" and printed on the pack. For 1/4" pitch chains and for the 3/8" LP 91PX and 91VXL chains Makita offers the D-73748 file of the same series, 4.0 mm in diameter.

Which chains it fits

Makita lists D-73754 for 3/8" LP (low profile) chains, but the same pitch also covers chains for which Makita specifies a different file. Makita gives the 4.5 mm diameter in the data for its own 90PX chains - 3/8" LP pitch, 1.1 mm gauge:

• 191H00-0 - for a 25 cm bar, 40 drive links
• 191H01-8 - for a 30 cm bar, 46 drive links
• 191H02-6 - for a 35 cm bar, 52 drive links
• 191H03-4 - for a 40 cm bar, 56 drive links

For the 3/8" LP 91PX and 91VXL chains Makita specifies the D-73748 file (4.0 mm). For its own 90PX chains Oregon specifies a 4.0 mm (5/32") file - with an Oregon chain, go by the marking on its box.

Among the compatible machines Makita names the DUC353 cordless chainsaw (2 x 18 V, 35 cm bar). It comes with the 90PX chain 191H02-6, and the DUA301 pole saw with the 90PX 191H01-8; for these Makita gives 4.5 mm. Makita also offers 91PX chains for both machines - for those it specifies D-73748 (4.0 mm). If you are not sure which chain you have, check its designation and the recommended file diameter in the saw's instruction manual - Makita refers to it explicitly for correct sharpening.

How it is used

The 1/4" shank fits straight into the bit holder of an impact driver or into the chuck of a drill driver. Makita prints symbols for both types of machine on the pack, and its list of compatible models includes the DDF482 cordless drill driver. The chain is sharpened in place, without removing it: switch the saw off (remove the battery on a cordless saw), tension the chain and clamp the saw or the bar firmly.

The diagram on the back of the pack shows two things. First, the file is held level - at 90° to the plane of the bar. Second, it sits so that 1/5 of its diameter is above the top plate of the cutter. The filing angle, seen from above, is 30° for the chains D-73754 is intended for. To keep the angle the same on every cutter, Makita sells a separate magnetic guide, D-75605: a plastic template with 2 magnets that attaches to the bar, with lines for 25° and 30° and holes for checking the required file diameter. The guide is not part of this article.

Sharpening tips

• Give every cutter the same number of touches, so the cutters stay the same length and the chain cuts straight.
• Sharpen all cutters on one side of the chain first, then turn the saw around and do the other side.
• Guide the file from the inside of the cutter to the outside.
• Work with light pressure and moderate speed. The diamond coating does the cutting; heavy pressure heats the cutter and wears the file faster.
• After sharpening, check the height of the depth gauges with a chain gauge - this is what Makita recommends.
• Wear personal protective equipment. The pack shows safety glasses, ear protection, a dust mask, gloves and safety boots.

Care and replacement

After use, brush the metal dust off the working part and store the file dry, apart from other bits, so the coating is not knocked. A diamond file is not resharpened: once the working part is worn smooth and the file stops removing material, it is replaced. Makita does not give a number of sharpenings per bit - it depends on the pressure, the speed and how worn the chain is.

Technical specifications

Makita 1/4" hex file series - which diameter for which chain

3/8" LP appears for both D-73748 and D-73754 - the chain designation decides: Makita 90PX - 4.5 mm, 91PX and 91VXL - 4.0 mm.

What's in the pack

• 1 Makita D-73754 round file bit, 4.5 mm (11/64"), 1/4" hex shank - in a blister
• A diagram of the file position and personal protection symbols on the back of the pack
• No angle guide - the Makita D-75605 magnetic guide is sold separately
• No driver, drill or chain

Questions and Answers