Machinist’s Hammer

This is my rendition of Marc Lecuyer’s Machinist’s Hammer project. Marc has provided a thorough tutorial on how to build this hammer on his Youtube channel and drawings are available for download on his website.

I was inspired by this project as it combined a few lathe techniques which I had not previously attempted. These include: long taper turning, short taper turning, knurling, form cutting and four-jaw work holding.

I followed Marc’s videos pretty closely, the most notable deviation was that I used 20 mm round 304 stainless bar for the handle (stock which I had on hand) instead of 19 mm steel. I also used matching 20 mm 304 stainless square stock for the hammer head.

 

 

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The handle comprises of a tap cut M10 thread on one end and a 12 mm deep drill on the other end. I believe the deep drill is to reduce the weight of the handle and improve the overall weight balance. The hole is later covered with a press fit cap. The handle was knurled and then the radius cutter shown above was used to cut the 5 mm radius which transitions into a 5º taper. Fortunately, one of the lathes which I have access to is equipped with a taper attachment, which was used to turn the long taper.

Even though the handle has been hollowed out I still feel that the centre of gravity is slightly too far towards the handle end of the hammer. This may be partly due to the fact I used 20 mm stock rather than 19 mm as specified. I may still drill out the pressed in end cap and deep drill the handle with a larger sized drill, possibly 13 or 14 mm, to further reduce the weight of the handle.

Dialling the 19 mm square stock in the four-jaw chuck.

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Short taper turning by hand using the compound slide, taking care to result in a perfect parabolic curve where the taper surfaces meet on each flat face of the hammer head.

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Completed hammer head, ready to have M10 hole drilled and tapped to accept the hammer handle.

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Brass hammer tip parallel machined, drilled and M10 tapped.

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Test fitting the hammer head.

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All of the completed parts prior to assembly. Hammer handle, brass tip, acetal (Delrin) top, hammer head and press fit end cap.

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Fully assembled Machinist’s hammer.

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Overall I am happy with how this project turned out and I learnt a lot of the new turning techniques as mentioned above. I will mostly likely make the modifications to address the hammer weighting issue in the near future.

I think the knurling could be improved somewhat, the alignment is not quite right, resulting in a not quite perfect diamond knurl shape, but the finish is nice and uniform so I am happy with it for now. I was working within the constraints of the tool I had on hand. I am thinking that my next project will be to build a pinch type knurling tool, I see Hemingway has some nice kits available…

EDIT: I ended up drilling out the handle to a diameter of 13 mm and about 116 mm deep. I then reamed a short section to 14 mm and made a new press fit end cap to fit. The weight balance is now greatly improved and feels much better in the hand.

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