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Building a better pizza cutter, the third wave - Doug Ayen's Blacksmithing Blog [entries|archive|friends|userinfo]
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Building a better pizza cutter, the third wave [Jun. 5th, 2013|12:41 am]
Doug Ayen

Series 1 was the original, in use in my kitchen for several years -- lacewood handle, damascus blade; series 2 was the last set, with 3 useable blades and 2 completed cutters. TIme for series 3.

The last set of pizza cutters I made taught me a lot. For one, there's no way that doing it all by hand is going to scale to any sort of production -- if it's going to take 20+ hours each, I won't even consider selling them -- too much time investment to be worth it, they'll become gifts to loved ones.

The 4 damascus (pattern-welded) test pieces resulted in two useable wheels: one I mangled on the lathe (the cable damascus piece) and one tore itself apart turning heat treatment, warping beyond recovery and with a crack all the way from face to face.  Sadly, I forgot to drill out the center hole in one of the surviving pieces, so it still sitting on the shelf for when I can get at it with a torch and soften it enough to ream it out for a bearing.

Somewhat surprisingly, the piece I expected to fail, the differentially hardened wheel, came out ok, with just a little bit of warping. It's size is impressive, 3.5” diameter, but I've learned through research and experimentation that larger isn't necessarily better. The larger the wheel, the larger the contact area, therefore the more pressure required to cut. 2" seems about ideal. It sure is pretty, though.

Bearings -- I had the idea of using sealed "cam follower" bearings which come pre-assembled, but they're expensive, somewhat fragile, and probably overkill for a hand-held pizza cutter. Every commercial pizza cutter I've seen uses just a plain steel-on-steel simple bearing:  cheap, reliable, and while it won't hold up to high-speed operations, it should be fine for chopping pizza into pieces.

What makes these cutters superior to what you can buy at WallyWorld? 1: sharpness. I've yet to meet a really sharp out-of-the-box pizza cutter. 2: steel quality: most commercial cutters are a relatively soft stainless, so what edge they hold doesn't last long. 3: beauty: pattern welded steel, hamons, and exotic wood handles set them apart. 4:  weight -- my blades are thick, about 1/4" at the hub, where as the cutters I've seen in stores are all thin, about 1/16" to 1/8" maximum. The added weight gives a good heft to the cutter, making for a good easy cut.

So, that brings me to series 3 of the cutters. For this series, I'm trying to reduce the amount of time required to make the cutters, starting with getting the rounds. For the differentially harded (hamon) wheels, I bought some cheap drops of W1 2" round, and a fast-cutting chop saw -- cuts out a disc in about a minutes. In addition, I had a problem on the lathe with the steel near the edge flexing away from the cutter on the lathe -- to fix this I cut off a 1" chunk of the W1 round, chucked it in the lathe, turned one face flat, turned the other side concave with about 1/4" depth, then drilled and tapped a 1/4" x 20 hole. The concavity supports the edge as the steel thins out, allowing the bevels to go straight from hub to edge without “clam edge” or requiring excessive grinding. The finish could use work, but it’s a start.

For the first test piece, I took the thinnest of the slices, one I would not consider "meaty" enough for a production piece, and center drilled a 1/4" hole, and affixed it to the faceplate I made earlier. It seemed to work pretty well, but my lathing setup didn't achieve a good surface finish, and the two sides have different angled bevels. Still, as a test piece, it was fairly successful, though it still took too long to complete.

For the second test piece, I decided to try a different approach, Instead of manually adjusting the cross slide to carve out the bevels, I adjusted the cross slide to move at the bevel angle. Sadly, the handle for the long-axis cross slide travel interferes with the trans-bed cross-slide. I removed the wheel, and it seems to work ok, if a bit rough as I have to use the coarse handwheel to control the x axis.

I noted during this bit of turning that I was getting some heavy vibration -- enough that a stud, a bolt, and nut, all different sizes, came off the machine. Before starting her up again, I'll need to figure out where those came from. Also, the main drive belt, a cog and toothed belt assembly, is so loose it's slipping under load, so I’ve ordered a new belt.

Ultimately, if I decide to go large-scale with this, I'll be getting a CNC lathe to do the majority of the work -- but that's $3000 or so, and I have other things I'd like to buy first with my shop money. More on that later, but one goal for this year is to get some things sold for cash, and more than just materials cost, and get some equipment to make production go faster.

So, next steps:

1) Fix lathe up

2) try the new setup on a test piece, time how long it takes.

3) Once I have a few pieces lathed up, grind and polish to remove tool marks

4) clay up and heat treat

5) Bearings, handles, finish up and get online somewhere (Etsy, ebay, maybe an amazon store?)

6) Make some damascus pieces once lathe process is dialed in

7) profit?


[User Picture]From: rmd
2013-06-05 11:47 am (UTC)
Very cool.
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