KEYWAY CUTTING TOOL

This is a dedicated tool for making square holes and  keyways.   It is  mounted on the lathe cross-slide and its handle is used to produce the cutting strokes.   With this design the lathe carriage is locked, not like other methods where moving the carriage provides the force for cutting the keyway.  An adjustable "stop collar" is included on the reciprocating shaft.  

Two versions of keyway  cutters  are made as shown at the end of this article.  The tools are very similar, but designed for use on different lathes.



1. Making one of two studs used to anchor the block to the t-slot of the cross-slide.

The stud  diameter is turned to the same size as the t-slot width.

2.
Slotting  reciprocating shaft to  fit operating handle thickness.  Slot width is 6 mm.

3.
Boring the inner diameter of adjustable stop collar of the reciprocating shaft.  Hole diameter is 16 mm.

The stop collar is later cross-drilled and tapped for set-screws.

4.
Rough cutting the tool's base from a block of mild steel.  It's 40 mm x 60 mm.

5.
Drilling  two holes for fixing body to cross-slide's t-slot. 

Hole depth is approximately 75 mm, and hole straightness is important.  Clean drill flutes and inspect often.

6.
Fix the body to the cross-slide using the t-slot. Drill the center hole for the reciprocating shaft.

7.
Bore the center hole to 20 mm to receive the bush shown below.

8.
Turning the shaft bush;  material is brass.

The outer diameter is carefully turned for an interference fit in the 20 mm hole of the base.

The inner diameter is sized for a tight-sliding fit with the reciprocating shaft.

9.
The parts are completed except for the handle.

The two black screws on the top have small holes in their centers to allow the application of oil to the reciprocating shaft and bush.

10.  The end of the handle is rounded by manual filing, using two temporary cylinders as a guide.



11.
Machining the tang section of the operating handle to receive the wooden handle.
12.

The handle is made of laminated wood, turned and tapered on the lathe.  The center hole is 14 mm.  I chose to stain and lacquer the handle, but of course, other finishs can be used.
13.

Assembled  keyway  cutter  with HSS bit installed.

Ready for first trials.


14.
Making a keyway  for a gear.

The lathe carriage is locked in place.
15.
Cutting depth is 0.25 per stroke.
The gear is made of hardened steel (SC45 in JIS)
16.
Successfully completed.

17.

More keyways were cut in gears of hard steel, 45C.   The cutting remained easy without  significant tool dulling. 
2nd cutter tool

18.
The same procedure is used to make  a second keyway cutting tool for another lathe needing a lower reciprocating shaft.


19.
The second keyway  cutter uses a mild steel bushing, lubricated via the grease nipple on the top.
20.
Both keyway cutting tools.