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The 4th Dimension...
It's funny how fast time just flies by...I wanted to do this about 4 years ago, but am just getting around to doing it now. In the last week or so I essentially did a case study on pineapple models for various applications. It is amazing how much leeway there is in our collective agreement of what we perceive as being a 'pineapple'! Some are just criss-cross patterns, others have 4, 5 or 6-sided polygon textures, and some are not even really pineapples at all, but artichokes or some other strange permutation. It was an interesting study. It would have been easy to just buy an existing model, but I wanted my own original model, with no strings or copyrights to worry about.
Yesterday I went to the food store to peruse the produce section. I spent a good solid 5 min rooting through the pineapples to 'find a good one'. On sale no less for $2.99! I finally settled on one, and then prepped it for scanning. I shaved off all the spikes on the body of the fruit so that they didn't wind up being the dominant texture. I also trimmed off some of the top leaves - which are ALWAYS a problem since they don't really have much thickness to them and they create a lot of undercuts, as you can see in the screenshot of the data. It's kind of a moot point because 4th axis machining doesn't let you get to undercuts like a 5 axis machine could. It's really no different than 3 axis machining in this regard.
http://i772.photobucket.com/albums/y...hinoRender.jpg
I've scanned a lot of natural 'models' over the years, and what's funny is, in nature, there is no such thing as 'perfect' as it relates to symmetry and the ideal layout, shape or config for woodworking. I'm sure Fibonacci would prove this wrong, but in my experience, the only 'perfect' pineapples I've ever seen were fake! Such is life when dealing with natural materials and models.
I had some teak glue-ups sitting around from another job and rather than wait for a full-scale size glue-up to dry I decided to jump in and machine this. It was pretty dense stuff so I was conservative with speeds and stepdowns. The original is about 11 inches or so tall and this one worked out to be around 7"+ in length. I scaled it down to match the 3.875" glue-ups. The leaves were machined down to an 1/8" ball because a 1/16 would have never made it that deep. I lost a pretty decent number of leaf tips while machining, but I was expecting that. The body/bulb itself was machined with a 1/16" ball to capture all that fine detail, although it could have used a 1/32" ball to really get it all...but I want to go to bed some time this century!
Here's a shot of the original and the scaled down one. I tried to clock them in the same position for comparison:
http://i772.photobucket.com/albums/y...nalAndCopy.jpg
I'm not a good photographer - as you can see! But here's another with the carved one in the palm of my hand:
http://i772.photobucket.com/albums/y...yPineapple.jpg
It really came out well. I tried taking a few pics of it right off the machine, but it didn't show up well. I slapped on 2 coats of shellac in about 15 minutes and buffed the body with a scotch pad in between. This made it a lot easier to see the detail. At some point I'll probably dumb down the leaves to make machining cleaner and faster.
This was a good test for some new indexer hardware I am running. I've got a few more rotary models that I scanned and will be machining soon...so stay tuned.
-B
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Excellent work as usual!
Once you had a 3D model, how did you toolpath it for 4 axis cutting?
Just curious.. how long did it take to cut? You mentioned wanting to go to bed the same day... so I can only guess around 10-12 hours? Perhaps one of the reasons not to cut 1:1 size!
Indexers are fun.
Thanks for the photos.. kewl!
D
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I'll bet the one on the left tastes much better then the one on the right:D
What is this "new indexer hardware" you mention?:confused:
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Nice write-up and nice work! The wood one looks almost good enough to eat - probably be a good source of fiber too. I find the wood grain beautiful but distracting - I had to tune the grain out to look at the scanned shape. What will the final finish be? Or was this one just for experimentation purposes?
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Hey guys - Thanks for the compliments.
This one was toolpathed with DeskProto 6 Multi-Axis Edition. I was very conservative with the depths and speed of cut. I ran a total of 5 toolpaths so that I could sneak up on the finish cut. Teak is pretty dense stuff - I'd say on par with Red Oak, maybe a little harder - and it was only being held by compression between 2 drive points, so vibration is always a concern. It took about 11 hrs total (4.5hrs with 1/16" ball on body only, @ 0.003" SO, 3,2 IPS). I borked up the C2 on the roughing because I ran C2 instead of my custom C4 which zeroes 1 inch below C2 height on top of the tailstock pad. So my roughing final pass was an inch higher than it should have been...So I had to run it again which meant another hour of machining time. If I had to run it again, I think I could get it down to around 6 hrs total - maybe less than that with some other tweaks.
The indexer is a warmed over Rikon setup parallel to the Y axis, running Alpha controls. I'm running a 10:1 low backlash planetary box right now, but will be swapping it out for a 50:1 Harmonic box (near zero backlash) after the cable comes in for the electric brake, since it differs from the standard accessory cable. After messing with the factory indexer offering and a few other of my own setups, I'm quickly closing in on the ultimate indexer setup. Super tight, super torque, super resolution & NO compromises! I've got some really hot 'twists' on a few indexer concepts that I'll post at a later date. They are still in R&D at the moment - but I guarantee they'll make any indexer lover's head spin when you see them! :cool:
The finish will probably stay 'as-is' on this one. I did it for me, so I don't need to make it any prettier than it already is! :D I don't have many carvings that haven't been sold, but I think I'll keep this one around. It's pretty heavy for it's size & looks great on the bookshelf. I might do another one full size in Duna just to see how fast I can crank it out.
-B
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I look forward to seeing more details about that super-indexer.
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"I've got some really hot 'twists' on a few indexer concepts".....did anyone else pick up on that cryptic hint?
I'll be interested in see what comes out of that mind of yours!:D
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50mm Trupan glue-up @ 6x6x16"...I got expedient and didn't let it dry as long as I should of....so I lost the center toe @ the glue line. Otherwise, not too bad. 40 min on roughing and 2:20 on finish with 1/8" ball. I didn't feel like running the 1/16" so I left it as is...I have a few tweaks I want to do to it before running it again...But I might run the pineapple again full scale this time because it is hard to really appreciate the texture on the one above.
http://i772.photobucket.com/albums/y..._0068Large.jpg
-B
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Simple heck!!
That thing is outrageous.
