Monday, November 16, 2015

A Ming-Inspired Cabinet (9)

While I’m letting most of the bubinga for this project sit for the next few days, and with more bubinga about to go into shipment, I thought it would be worth exploring what sort of job the Zimmermann FZ-5V would do with its helical shell mill.

I had planed the leg stock to a solid ¼" over dimension, and could have taken them down further by planing them in the SCM or Makita shoebox. However, I’ve been finding that the planers are tending towards a little bit of tear out with some of the figured bubinga, even with fresh knives fitted, so taking them right down to dimension with a planer seems decidedly unwise. I thought therefore, that it would be worth a look-see with the milling machine, as I had been considering whether or not the Zimmermann would be a good way to process the leg shapes into their ultimate cross-section, which is rhomboidal. Getting these legs shapes done precisely is the most important part of cut out for the entire support stand, so I will do my utmost to get the results I want

This was mostly a test, and if it went awry there is plenty of material left on the legs to correct afterwards, not to mention that there is a spare leg to mill. The set up is pretty basic, with the bubinga leg placed across the vise and sandwiched between a couple of precision parallels to spread the clamping force:

The shell mill is helical with a positive rake:

Here’s how this process looked, with a 0.3mm deep pass:

I realize that might not be the most exciting youtube clip ever, but I enjoyed watching the machine do the work. The machine takes shavings, and it can take them in thousandth of an inch increments.

What I obtained from the shell mill was not what you would call a polished surface, like you can get off a hand plane or super surfacer, but it is very clean, with no significant traces left of the cutter and absolutely no tear out:

The lack of telltales from the cutter means the head is trammed in correctly, and the surface quality is better than what I would obtain out of my planer with 4-knife Tersa. The idea here is to get the surfaces close to the mark, and finish them off with a hand plane and/or super surfacer.

The leg came out very square and within 0.1mm of dimension without me having to have been particularly fussy about getting to those results:


I enjoyed making shavings in a whole new way today. That face mill worked very well I thought and should be the cat’s meow for processing these leg section into rhomboidal shapes, which will be the next step with these pieces once I have completed S4S with all the pieces.

That’s it for installment 9 of what promises to be a lengthy build thread. Hope to see you again next time.

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