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Post by birkie on Mar 23, 2018 2:49:43 GMT
Out of curiosity, I created a CAD drawing of one of my aluminum DR freezing blocks and sent it to a few online CNC milling shops for a quote to see how much it might cost to reproduce them. Here's a link to the model - one of the sites I uploaded it to had a collaboration tool. If you give an e-mail address, it looks like you can visualize, play with, and comment on the model. Otherwise, the raw file Here on google driveThat particular site wants over $200 for a single block, something like $80+ at scale. One reasonable quote I found elsewhere had a pricing structure (exclusive of shipping) for 6063 aluminum with a raw but deburred finish as follows: qty | price each | 1 | $186 | 10 | $40 | 20 | $28 | 50 | $18 |
That model would fit a standard pig evaporator of a DR2 or DR3. The DRA2 would be a little shorter, but I figure it would be most economical to just use one size and cut off an inch or so.. Would anybody be interested? I currently have four pig evaporators - two on a DR3 (which came with its original freezing blocks), and a DR2 and DRA2 that are missing their freezing blocks. If enough people are interested, it might be worthwhile to pursue.. maybe get some additional quotes, and figure out the specifics.
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Post by Travis on Mar 23, 2018 3:30:08 GMT
I need some.
I don’t remember if I have any aluminum ones or not. It seems like I do but I don’t know where it is.
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Post by ckfan on Mar 23, 2018 4:39:09 GMT
I need one for my DRA. You never cease to amaze me!
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Post by joneske on Mar 23, 2018 14:23:00 GMT
I need one for my DRA2. Thanks for looking into this.
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Post by timeswelding on Mar 24, 2018 0:30:09 GMT
I've often thought of having them cast. Milling them from billet is a long drawn out process. It'd be much cheaper to cast them if enough were warranted.
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mach
7 Cubic Foot
Posts: 135
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Post by mach on Mar 24, 2018 16:42:51 GMT
Sorry, I'm not familiar with a freezing block. Its a piece of aluminum bar stock rounded on one side that sits in the bottom of the evaporator and the ice tray sits on it? Any reason not to cast it? Any requirements for surface finish? Borrowing birkies image, under the ice tray?
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Post by birkie on Mar 25, 2018 2:39:20 GMT
Sorry, I'm not familiar with a freezing block. Its a piece of aluminum bar stock rounded on one side that sits in the bottom of the evaporator and the ice tray sits on it? Any reason not to cast it? Any requirements for surface finish? Borrowing birkies image, under the ice tray? All the surfaces of those brine-filled DR evaporators were curved (due to fear of deforming due to pressure differentials), and have a cylindrical interior. So the freezing block is an aluminum piece that fits the curvature of the interior, provides a flat surface for the ice tray, and conducts heat away from it so that it'll actually freeze. The original blocks were porcelain coated cast iron, then they switched to bare extruded aluminum. Casting aluminum would probably be fine, though it looks like most casting alloys are less thermally conductive (it looks like 50-70%). I don't know if the thermal conductivity of the freezing block is a limiting factor or not, so it's unclear if that would make a practical difference. My blocks have a smooth surface (which makes sense if it's an extrusion). I don't think they're anodized. I've often thought of having them cast. Milling them from billet is a long drawn out process. It'd be much cheaper to cast them if enough were warranted. The quote I got has them solidly in the $20-$40 price range for quantities from 10-50, with a 15 day turnaround. , which I'd say is reasonable. If casting is cheaper, then that is even better. Are there any places you'd recommend for getting quotes?
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mach
7 Cubic Foot
Posts: 135
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Post by mach on Mar 25, 2018 3:51:54 GMT
Ok I'll have a go at casting them from lost foam or a 3D print. How long are they (I can't open the stl until I'm back home)?
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Post by birkie on Mar 25, 2018 4:14:26 GMT
Ok I'll have a go at casting them from lost foam or a 3D print. How long are they (I can't open the stl until I'm back home)? Oh, wow. You can do that? That would be fantastic! They're 7 7/8" long, and 3 1/4" wide. The cylinder they fit into is 7 7/16" in diameter. They have flat sides down their entire length that are 3/16". Here's a picture of a cross section:
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Post by Travis on Mar 25, 2018 4:15:55 GMT
I can measure an old one. The 27 unit came with two! They're heavy, like bonk someone on the head dead heavy!
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Post by birkie on Mar 25, 2018 4:18:17 GMT
I can measure an old one. The 27 unit came with two! They're heavy, like bonk someone on the head dead heavy! It'll be interesting to see if the cast iron ones are different.
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Post by Travis on Mar 25, 2018 4:21:32 GMT
The cast iron ones are much larger than the aluminum ones.
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Post by birkie on Mar 25, 2018 4:34:56 GMT
The cast iron ones are much larger than the aluminum ones. I just took a look at one of the pictures you sent of that machine.. oh gosh.
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mach
7 Cubic Foot
Posts: 135
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Post by mach on Mar 25, 2018 6:18:55 GMT
Ok I'll have a go at casting them from lost foam or a 3D print. How long are they (I can't open the stl until I'm back home)? Oh, wow. You can do that? That would be fantastic! They're 7 7/8" long, and 3 1/4" wide. The cylinder they fit into is 7 7/16" in diameter. They have flat sides down their entire length that are 3/16". Here's a picture of a cross section: Yes aluminum and bronze. Copper I haven't tried. Cast iron, no but I know someone who may still do it and is setup for large scale sand casting. Lost foam would be easiest. My setup is just a hobby one.
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Post by Travis on Mar 26, 2018 5:41:12 GMT
The old ones are 4 3/8” x 9 1/4”
The newer aluminum ones are 3 1/4” x 7 3/4”
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