From: Mike  |  Date: September 21, 2006

Aspen Grove block 1 is carved and side two (block 2) is carving now "“ at this rate, I'll be done by the end of this week, or maybe early next"¦ Currently calculating toolpaths for 7th block "“ when it's done, only one to go! LONG day today, and I'm VERY dirty and dusty! Going home now to shower, eat, and sleep "“ back at it in the morning to finish #2 and move on to begin carving #3"¦

(Dave replied during a Skype conversation ... )

From: Mike  |  Date: September 22, 2006

I've completed carving of blocks 1 through 3 and am currently surfacing block 4 (2nd side of 2nd block). I've been planing off about 15 thousandths of an inch from the surface in order to make the blocks flat and parallel (they seem to be out by about 1/100th inch as they come from Matsumura "“ that means the faces are non-parallel by that amount)"¦ Then I sand smooth to remove machining marks with 220 grit and finish with 400 grit to a dull shine.

I'm using the same bitmap contours as with block set #3 which are the ones I sent you last spring "“ those bitmaps look very good to me still. But I've vectorized them with more precision than before and I've redone all the toolpathing using a much closer tolerance (now about 1/1000th inch tolerance) in order to try to carve more of the fine detail than before "“ this means it took about twice as long (24 hours) to calculate the toolpaths, and is taking about three times longer to machine, but from the way the first three blocks look, it's worth it "“ these appear to me to be a substantial improvement over the previous set (at least according to my memory)!

The 45 degree vbit is (so far) providing much greater precision than the 60 or 90 degree vbits I've used in other carving. This is like"¦ DUH! Each axis of my machine 'moves' in increments of about .002 inch. I previously carved the blocks about .07 inches deep (35 'clicks' vertically) using a 90 degree vbit on the first (plywood) blocks, so the narrowest mark I could theoretically make should be about .004 inches and at .07 inches deep the diameter would be .14. With a 60 degree vbit, the narrowest mark I can make would be about .0023 inches and at .7 inches deep, the diameter would be about .08 "“ this is what I used for on the maple and cherry sets "“ you have the cherry set carved this way.

This week I'm carving the Woodlike Matsumura blocks .1 inches deep (50 'clicks' vertical instead of 35 at .07) and I'm using a 45 degree vbit. So the narrowest mark I can make is theoretically about .0017 inch and at the full .1 inch depth the cut is only .083 inches in diameter, so it's clear why these are turning out better all the way around "“ about 5 times greater precision, assuming, of course, that the steeper tiny pyramids survive machining and that I accurately zero the vertical axis exactly at the surface of the block"¦

4.5 million lines of code to carve these blocks and about 3500 feet of actual carving, so I still have a LOT of hours of machining ahead of me at this point "“ might be finished closer to the END of next week it now appears.

From: Dave  |  Date: September 23, 2006

... but from the way the first three blocks look, it's worth it "“ these appear to me to be a substantial improvement over the previous set (at least according to my memory)!

OK ... hope you keep the bit sharp! That steeper angle might mean more mountain tops getting chipped off ...

You said the other day:

I'm VERY dirty and dusty!

How much actual 'hands on' do you have to do with all this? And how much input does the toolpathing process need from you (decisions, etc.)? People have been curious where the 'line' between you and the machine is falling ... how much is 'automatic', and how much is 'artistic' ...

From: Mike  |  Date: September 24, 2006

The 'line' between me and the machine falls mainly at the tips of my

fingers, I suppose. I've described this before, I think, so you already

know all this -- but again, briefly:

I photographed the Aspen Grove about 50 yards from my Mom and Dad's home in

Aspen, Colorado. I manipulated the image using PhotoShop, both rotating and

distorting it in order to make a 10x15 inch (oban) image which I liked.

Then I scaled it up to 600 dpi and began adjusting the tonal curve until the

image contained roughly equal areas of tone while maintaining an overall

tonality which appealed to me. Then I began to enormously simplify the

image. First I converted it from color to grayscale, then eliminated areas

too small to carve while still maintaining sharpness and detail (something

of a trick actually). After many hours of back and forth adjustment and

simplification, I had only nine values in the image (white, and eight evenly

stepped grays going to black), each covering roughly the same area (square

inches) of the image and the smallest piece of each tone was only a bit

smaller than I might actually be able to carve. I added kento registration

and masked borders for carving so the bitmapped image became a bit larger

than the blocks I would carve. Then I built the contours to be carved for

each block (I chose this particular image in part because I could avoid

having to include paper support areas which could complicate instructions to

the printer and make it easier for mistakes to occur in printing).

I output

the contours for each block to a 1-bit bitmap (black and white) and

vectorized the perimeter of each black contour -- in effect, each area to be

carved away was outlined with vectors. At 600 dpi and using a 1.2 pixel

'average' for the vector conversion, and eliminating any contours of less

than 6 pixels (.01 inch), the outline of each area to be carved was

contained in a dxf file. Then I loaded the dxf vector information into my

toolpathing software, defined the router bits I would use during machining

(their geometry, including shape, diameter, inches per second, offset for

clearing strategy, and similar information) in this instance, a 45 degree

V-bit and a 1/8 inch upspiral end mill. Then I computed the toolpatsh --

using the v-bit to engrave the outline of each contour (calculating the

Z-axis height of the v-bit in order to accomplish very narrow lines) and

used the v-bit to clear interior areas too narrow for the eighth inch

end-mill to reach. Larger areas were toolpathed for clearing with the

eighth inch end-mill. Then I saved the toolpath instructions as text files

in a format my CNC machine can interpret. Although the toolpath files

contain some instructions to set the speed of tool movement and other

parameters, and many instructions to lift the bit out of the block and 'jog'

to a new location without cutting, more than 99 percent of the toolpath file

instructions are "move in three dimensions from the current location to

x,y,z where x y and z are the measurement in inches from 'zero', a point

about six inches above the bed of the machine at a corner. All these

millions of lines of instruction are generated automatically from the

parameters I enter and using the vectors I built from the original image.

Then I decide how to mount the block onto the bed of the machine. In the

case of the current block, I use vacuum. I built a vacuum plenum over my

machine bed -- it's a 49x96x1 inch sheet of light weight MDF and I machined

away deep grooves from the bottom side so it is 'waffled' and I screwed it

down to the bed of my machine and caulked the sides all around so they are

air-tight. I have a Fein shop-vac attached under the bed to provide about 1

pound per square inch of suction. I cut 10 3/4 x 16 inch (the size of the

blocks you provided me) hole out of a sheet of 4x8x1/4" corrugated plastic

sheet, mounted the sheet onto the vacuum plenum and used masking tape to

seal the edges. Then I placed a block into the hole I'd cut in the plastic,

turned on the vacuum, and taped around the edges of the block onto the

plastic to effect a tight seal. So the block is held down by about 172

pounds of air -- enough to keep it from moving around during machining.

Then, since the two cherry-faced sides of the block were not completely

parallel or flat when they arrived, I used a 1/4 inch end-mill to plane

about 15 hundredths of an inch from the surface of the block (I do this with

a 'cut rectangle' command to my machine giving parameters for how deep to

cut, how long and wide, the step size (tenth of an inch for these) and that

it's to begin at the outside and move in until the whole surface has been

machined.

Then I sand the freshly machined surface (already quite smooth, actually),

first with 220 grit and then with 400 grit. The whole setting the block,

zeroing the tool, machining flat, and sanding process takes about 30 minutes

per side.

Then I install a 45 degree vbit into the router, zero the vbit to the

surface of the block, check the zero carefully by machining small lines at

the edges until I'm satisfied with the accuracy of the setup, load the

toolpath instruction file and run it. I watch for a few minutes to make

sure all appears to be 'right', then I run upstairs (and write this email)

and do other stuff, usually checking on progress every hour or so until the

carving has completed (for these blocks probably an average of 7 or 8 hours

of v-bit carving). When the v-bit movement has been completed, I lightly

sand the surface with 400 grit to clear any burrs. Then I remove the v-bit

and install an eighth inch end-mill, zero it to the surface of the block

(doesn't require as much precision as it's only clearing and cutting kento),

then load and run the toolpath for that tool and block. On these blocks

that's only 30 minutes to an hour to complete.

Then I blow the dust and chips from the carved surface, turn off the vacuum,

remove the tape and either flip the block to begin the other side or (if

this IS the other side) put in a new block and repeat until done.

As I think I've mentioned before -- the ink and paper have NO idea and

receive NO information about what sort of tool might have removed the

portions of the block which don't print, so there's really NO way to

determine by looking at the print that the block was carved by router, by

hand, by fingernail, teeth, or whatever! The only evidence of the block is

the ink transferred from the UNCARVED surfaces, right?

OK, so where's the 'line' between me and the machine? I don't really

believe there IS any such line. The machine is an extension of myself in

exactly the way ANY tool is an extension of oneself. Mind goes, everything

else follows, right?

Minor disaster yesterday... My router shot craps mid-block-4... Picked up

another (and dropped $350) this morning and am now re-carving #4 which

should turn out just fine.

This thread continues in Aspen Grove (9) ...