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Third cholla bowl #1: Building the blank

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Blog entry by Dave Polaschek posted 05-06-2022 05:01 PM 735 reads 0 times favorited 9 comments Add to Favorites Watch
no previous part Part 1 of Third cholla bowl series Part 2: Second pair of pours for the blank »

Started making the pieces for another cholla bowl this morning, and figured there’s been enough interest in what I’ve done that I should write it up.

The first step is building a base on a faceplate for my lathe. I’ve been aiming at bowls that are 6-10 inches in diameter, so I generally put a pine 1×6 on the faceplate, and then put a couple pieces of 1×6 across that to get up to the size I want.

Then I cut it round-ish on the bandsaw, and turn it round (and about 10 inches in diameter) on the lathe.

I stick blue tape on the joints. That helps keep the epoxy from running through the joints and making a mess in my shop.

Next, I stick a piece of blue tape around the edge of the base. Just one or two turns, but I try to stick it to the edge of the base as best I can. I’m going to be pouring epoxy into this and I don’t want a leak.

I should note that I’ve already cleaned the cholla. If there’s any material in the middle of a piece, I poke it out with a long screwdriver.

Next is putting in the cholla. In my first two bowls, I stood pieces of cholla on end. This time I’m going to try laying them circumferentially.

If the pieces go a little beyond the tape, that’s ok. And if there are gaps, I plan to fill them with the next layer. So now it’s time to mix up some epoxy. 50ml of System 3 Fast Hardener, 100ml of System 3 General Purpose Resin, and 22 drops of TransTint Aqua for the first pour. That makes a fairly pale almost sky blue.

Second pour is another 150ml of epoxy (5 oz), this time with about 35 drops of Aqua, and 5 drops of TransTint Lemon Yellow. Definitely green, but I think still thin enough that it’ll let light through. I pour this aiming to hit areas that didn’t get any epoxy in the first pour (cholla will form dams) and I concentrated on pouring over pieces of cholla that looked dry inside. I also stuck in a few more pieces of cholla (small broken chunks) to fill any small gaps that looked wrong to me.

At this point, there are still a few spots where I can see the dry pine base. But after this epoxy cures overnight, I’ll put on another few wraps of tape, building the sides up to 1.5 to 2 inches high, lay in more cholla, and then pour the next two colors of epoxy. I’ll probably set the base slightly off-level so that the epoxy pools more on one side. I’m guessing I’ll have a total of four pours of two colors of epoxy (they mix a little, but the cholla will segregate the colors a bit, plus the first of two pours starts to harden before I get the second poured), and I’m leaning towards red and violet tints for the next batch.

-- Dave - Santa Fe



9 comments so far

View MrWolfe's profile (online now)

MrWolfe

1836 posts in 1580 days


#1 posted 05-06-2022 05:12 PM

Cool write up on your process Dave.
I like the idea of the homemade faceplate that is part of the epoxy disk, very clever.
Can’t wait to see the results of this piece.
Thanks for sharing.

View EarlS's profile

EarlS

5510 posts in 3805 days


#2 posted 05-06-2022 05:16 PM

Have you thought about doing the pouring process in a plastic garbage can that you could cut off when the epoxy cures?

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View Dave Polaschek's profile

Dave Polaschek

10272 posts in 2039 days


#3 posted 05-06-2022 05:19 PM

Thanks, Jon! I end up turning away all of that pine so far, but I’ve pondered leaving it as a feature ring… maybe this is the time I’ll do that.

Earl, I have, but I have a lot of pine scraps left over from my bookcase build, and blue tape is pretty cheap. And this way the edge of the “mold” can vary a little if I have a piece of cholla sticking out. And if I notice a leak mid-pour, I just slap on some more blue tape to plug the leak. Also, building the mold as I go means I don’t have a preset height limit. I make the blank thick enough to “look right.” That’s generally been in the neighborhood of 2” thick, but I might go thicker this time and stick a plastic tub in the middle to make the center of the bowl…

-- Dave - Santa Fe

View Oldtool's profile

Oldtool

3506 posts in 3647 days


#4 posted 05-06-2022 08:07 PM

Interesting design features Dave, like Mr. Wolfe said, waiting to see the results of this manner for the cholla segments being laid out.
How is that cholla wood to work with? It looks to be somewhat brittle, maybe breaks apart easily. I looked up cholla with Google and Wiki says ….. ”The cholla wood is made up of a ton of holes and is hollow through the center which provides a natural cover for shrimp to hide” You got an ocean near you?

-- "I am a firm believer in the people. If given the truth, they can be depended upon to meet any national crisis. The point is to bring them the real facts." - Abraham Lincoln

View Dave Polaschek's profile

Dave Polaschek

10272 posts in 2039 days


#5 posted 05-06-2022 10:05 PM

Thanks, Tom! I’m waiting to see how it comes out, too!

Cholla wood is super-hard. Makes hickory feel easy to work. If it’s all sound, it’s hard to cut too. There’s always some soft spots, but in a 1” diameter branch, if there are no soft spots, I need a boot on it to break it, and its hard to go through with the 2” capacity loppers.

Cholla wood is a little brittle. The “grain” is pretty linear, but if you catch a knot the wrong direction, rather than getting a little tear-out, you’ll lose a big chunk.

If you’re curious, PM me your address, and I can send you a small flat-rate of pieces. I harvested a bunch more from our yard, and when my neighbor saw me, he offered to give me all he collects from his lot. I took about half of it, but have a pretty good pile I need to hit with the pressure washer to get the spines off. What I send you would be mostly clean, but there’s no guarantee I won’t miss one spine.

No ocean nearby as far as I can tell.

-- Dave - Santa Fe

View Eric's profile (online now)

Eric

5035 posts in 1330 days


#6 posted 05-07-2022 12:36 AM

That is an interesting process Dave. Using the pine as a face plate and starting the base is a great idea. And the epoxy process sounds easy to do. It will be neat to see the finished product.

-- Eric, building the dream

View Dave Polaschek's profile

Dave Polaschek

10272 posts in 2039 days


#7 posted 05-07-2022 12:43 AM

Thanks, Eric. I was trying to figure a way to make the blank without having to buy a plastic bucket or something, and then I had all that pine left, so….

And yeah, the only real hard part is that I get some bubbles in the epoxy. I try to get as many out as possible by rapping the whole thing on the bench, but that can get sloppy if I’m not careful. But I’ll also come back and fill them later if I can.

-- Dave - Santa Fe

View doubleDD's profile

doubleDD

11282 posts in 3500 days


#8 posted 05-07-2022 02:39 AM

It will be interested to see the results with cholla laying on their sides. Ill be following Dave.

-- Dave, Downers Grove, Il. -------- When you run out of ideas, start building your dreams.

View Dave Polaschek's profile

Dave Polaschek

10272 posts in 2039 days


#9 posted 05-07-2022 02:43 AM

Thanks, Dave. I’m interested to see what I come up with, too. My brain thinks it might look pretty good, but sometimes my brain, it gets a mite confused.

-- Dave - Santa Fe

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