Quick, Cheap & Ugly Lathe Knives

[mlochala]

Ugly alert! No pretty girls here!

This is a set of quick and dirty carbide tipped lathe knives I made for use with my wood lathe. They are a combination of cheap ($1.99 each) Harbor Freight screwdrivers, leftover 5/16" key stock, and some inexpensive, replaceable carbide tips from eBay ($12).



The original plan was to just reshape the ends and then drill and tap the screwdrivers for mounting the blades. I didn't really put much stock into that whole "Chrome Vanadium" thing. Boy, was I wrong! I now have a new level of respect for Harbor Freight screwdrivers.

I had assumed that HF would have used plain mild steel with MAYBE a thin layer of tempered chrome vanadium, but, as it turns out, they were solid through and through. A couple of drill bits later with barely making a spot on the outside surface of the screwdriver shaft and I realized I needed to resort to Plan B.

Plan B was to use the square key stock for the blades, remove the handles from the the screwdrivers, and then press them onto the key stock. Again, that didn't work out as planned. Even after making a special puller to remove the handles from the shaft, I found that they were much better made than I expected. The handles withstood the force of using a simple puller made of 3/8" flat bar.

So, enter Plan C. I simply cut all but 1-1/2" of length from each screwdriver and then cut each length of key stock to 7". Then, using my best free-hand welding skills, I tack welded them end to end, and then finished the weld when I confirmed they were reasonably straight.

I did't spend much effort on making them look much better, as this was more or less just an experiment to see how well they work before investing much more time, effort, and $$$ into making a fancy set.

All in all, I think that they turned out reasonably well and should be much better than the worn out lathe knives I've had for a few years now that constantly require re-sharpening.

[Frank S]

I rarely do any wood turning but I like your approach.
If you have so much as a simple propane torch you can heat up the ends of about any screw driver to a dull red glow and allow it to cool slowly then most of the hardness will have been normalized and you should be able to drill them with most hardware store drill bits.
I've drilled holes in the blades of Craftsman, Snap-on Mac and other brands of screw drivers with a decent HSS black oxide coated drill bit many times without having to anneal them first. Using a slower RPM setting on your drill with higher down pressure helps as well sometimes.

[DIYer]

Thanks mlochala! We've added your Lathe Knives to our Woodturning category,
as well as to your builder page: mlochala's Homemade Tools. Your receipt:

Lathe Knives by mlochala

tags: lathe, knife

[mlochala]

If you have so much as a simple propane torch you can heat up the ends of about any screw driver to a dull red glow and allow it to cool slowly then most of the hardness will have been normalized and you should be able to drill them with most hardware store drill bits.
I've drilled holes in the blades of Craftsman, Snap-on Mac and other brands of screw drivers with a decent HSS black oxide coated drill bit many times without having to anneal them first. Using a slower RPM setting on your drill with higher down pressure helps as well sometimes.

Thank you very much for the advice! I will give that a try, next time around.

[wizard69]

Thank you very much for the advice! I will give that a try, next time around.

Give it a try but do realize that even normalized you will need a better quality tap.

What I like about your approach is that it puts a pretty much useless tool, often acquired in sets, to work. One youtuber, Koon Trucking I believe, refers to them as miniature pry bars. That pretty much is the current usefulness of flat bladed screwdrivers in many shops.