While I’m letting most of the bubinga for this project sit for the next few days, and with more bubinga about to get shipped out to me I am holding off on any more rough stock breakdown for the time being.
I thought it would be worth exploring what sort of job the Zimmermann FZ-5V would do with its helical shell mill. A few people have been letting me know over the past couple of weeks that they are interested to see how I make use of the mill, so here goes ‘part 1’ in that regard.
I had planed the leg stock to a solid 1/4″ over dimension, and could have taken them down further by planing them in the SCM S630 planer or the Makita shoebox planer. 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 the pieces right down to dimension with a planer seems decidedly unwise. I’ll probably have to get the panels thickness sanded to remove the remaining 3/16″ of material standing in the way of final dimension.
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. I did receive the cutter used along with the machine, and it seems sharp, however I am unsure as to how worn the edges on the cutter actually are, or what sort of materials it might have been used upon previously. As it is right now, it seems to cut well.
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 overarching idea here is to get the surfaces close to the mark with the mill, and finish them off with a hand plane and/or super surfacer. I’m glad to know now that is a fully-realizable plan.
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 some 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 sections 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. On to post 10.