New sump; edge prep

[mattboy]

Hi Brian;

I'm making a new sump out of cyro gp to replace the extruded one I built just before the reactor course. I checked out the chat logs, and I'm trying to come up with a plan for really precise machining/prep of the critical edges with my router table. Between the logs and some thinking, here's what I came up with. Please advise!

First, i use the thin acrylic bearing strip attached to my fence with double stick tape to get clean edges on one piece, for example one of the sides. Then I use that piece as a template to get the other side exactly the same size. I then use the original side to get exact height of one of the ends (height of sides and ends is identical) and then use the bearing strip to get the width of the end clean, then use that end as a template for the other end and the baffles. (height of baffles is not a critical dimension). I should be left with sides, ends, and baffles machined precisely. When these pieces are assembled, they'll be a bit smaller; i.e there will be a decent overhang for the bottom. Weld that, then flush trim. Sound okay?

Thanks, Matt

 

[fergy]

Sounds fine. There's an even easier way to prep those edges, and that's by setting the off-feed side of the router table fence like yuo would for a jointer. In this case, you'd attach that bearing strip to the left side of the fence, then VERY PRECISELY position the fence so that the off-feed side is exactly even with the cutter edge on the bit. Now, when you push your pieces along from right to left, you'll remove exactly the same thickness as the bearing strip, leaving a finished edge. You just have to make sure you run each piece the same number of times on each edge.

B
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Ferrari 308 GTS

 

[mattboy]

Brian;

Yes, that's what I am planning on doing; attach the bearing strip, use that as a guide for the off side of the fence. I guess the way to adjust it is to set it up, put the work against the bearing strip, adjust the fence so that the work just touches the bit and the bearing strip, and there's a parallel "gap" between the work and the feed side of the fence. I was thinking, though, that once i got one piece the final size, it would work well as a template to make sure the other pieces were exactly the same size, I'm also going to buy a pipe clamp to line 'em up when welding.

Gettin' psyched for the skimmer class!

BTW, I read the recent thread about extruded vs cast on one of the boards. Jeesh, some people.... As a professor, I know exactly how there are a million know-it-alls out there.


Matt :roll:

 

[Modo]

I was thinking about building a small refugium as well. The above info was very helpful. But, I have one other questions. When gluing a tank like this would you still leave the small overhang to flush trim off later? Or would you try and glue precisely edge to edge?

I beleive a smaller tank we could build exactly as the base of the reactor, but would this work for larger tanks? This may have been in one of the lessons or chats, but I'm kinda slow.

Sorry to hijack Matt.

 

[fergy]

No, you need that overhang. If it's not there, the solvent will wick over the edge of the material, and screw up the face of the plastic.

BTW, I think for the skimmer class, you'll get a better idea of how to finish edges like you would on a tank. I think I'm going to make everyone hand polish. I just did some skimmers this weekend, and polished to the point you have a hard time finding the seams. It looks like the entire thing was cast as one piece. It's definately cool looking.

We had a reef club meeting at my place last weekend. Several people asked me how I bend the 1" acrylic. What they were looking at was the rounded over edges, which were then polished. They thought I had bent the panels. Rounding over and polishing definately looks nice...

BRIAN
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Law Discussion

 

[cybershark]

Gee does that mean that where going to learn polishing before everything is welded together this time around :lol:

 

[fergy]

Lol. I think so. The issue last time was that I didn't want to require people to buy all of the polishing supplies...I'm still wondering if I should. I'm wary of making the cost prohibitive for new students.

Think of it like this: would you be willing to buy sandpaper in 150, 240, 320, 600, 1200, 2000 grit, plus a set of micromesh for polishing up to 12,000 grit, and then a buffing wheel, buffing compound, perhaps a bench grinder to put the buffing wheel on, and Brillianize for the final cleaning?

You can get away with sanding up to about 600, but it's really hard to buff out those marks. It's easier to just go through the entire range, and then buff lightly for a few seconds. Also, the easiest way to do all of this is outside, with water running on the surface of the material. So, you can see my dilemma.

BRIAN
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Miscarriage / Still Birth Forum

 

[mattboy]

Brian;
I have an idea; after we finish assembling the skimmers, we could send them to you, and you could demonstrate polishing techniques on them 8)

Actually, I bet I could bug my friend the guitar maker here in San Antonio for help with polishing. Since he hand finishes each guitar with shellac "french polish" technique, he's got all sorts of stuff for this.

If anyone in the class is looking for a great $2000 classical guitar, that's really worth at least $3K, this guy is great. Besides, if even one of my classmates orders a guitar, I'm sure he'll help me polish the skimmer!

Matt

 

[fergy]

Oh, yeah, sure, send them to me. I'd love to spend the 2-3 hours it takes ;-)

BRIAN
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BMW 327

 

[agiacosa]

Fergy,

I was about to start gluing everything. I'd like to polish before assembly. Where can I purchase the sand paper? Also, you sand with your hand?

Thanks.

Art

 

[agiacosa]

Never mind. I found it.

I think most of us would purchase the extra products required to improve the quality of the final product. I did anyway. If I add all of the costs associated with the calcium reactor, I think it would have been cheaper to buy an MTC Pro-Cal at $695. Of course, when you factor in the feeling of having created such a quality product myself, it is priceless.

As always, thanks for the help.

Art

P.S., Home Depot is selling the Ryobi grinder for $39.99.

 

[fergy]

That's the bench grinder I use...you have to pull off all the safety housing, though ;-)

You can get sandpapers up to 2000 grit at an auto supply store. I use an electric palm sander, usually, with a spraybottle of water.

BRIAN
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Ferrari F50