Let's Build a (Dry) Sink

mshchem said:

Absolutely cabinet scrapers are the greatest tool ever invented!!! Especially when you have a (burnishing?) tool to get the burr just right.

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Pictured: Burnishing tool.




I know they make really nice specialty burnishers for scrapers, but to be completely honest: it's hard to beat a piece of old tool steel that's lived a long and happy life. I've also been known to use a 6"-long socket extension for really working the burr over into a heavy cut...but for a quick whet and reshape, a round-shank screwdriver ain't bad.

Substances were mixed, caffeine was consumed, things were done.

Pictured: Tape was used.




I tried a smidgen of the colloidal silica in the bonding mix this time; definitely a different feel and consistency. It worked well in the corners, where I intentionally left a bit of room in the joints for the mixture to really sink in. I might have left too much room because the resin didn't really want to stay where I placed it, but I'll handle that with the filleting mixture in the next few days. It's a learning process.

...and after a three-day tour of Europe, Scandinavia and the Subcontinent, we're back! But wait, there's less! Not only is the last side skirt installed, but all of the interior filleting is done...and the result is what most amateur composite technicians would call "a professional job" and what most professionals would call "grounds for being fired."

Pictured: Not just good, but good enough™.




...yeah...so, I've learned a few things:

• I am not good at this.
• People that are good at this have been doing it for years, and like most experts they make difficult tasks look extremely easy.
• Like most difficult tasks, filleting is best accomplished by committing to a course of action and just sending it; if you try to baby this stuff you'll end up poking and prodding it until it either gets mad at you and leaves, or decides to just starting kicking over and hardening...at which point it's even harder to work with than it was three minutes ago.
• Silica really does make an excellent filler compound for filleting mixture, but if I had this to do over again I would go back to using the chopped glass that I've used in the past; it's a bit coarser, but it's much easier to work with...so I would say that colloidal silica is more of an intermediate-level additive, and not really a beginner-friendly material. The main issue is that silica-thickened epoxy spreads like cake icing...and I really mean exactly that: it's extremely easy to apply and shape, but if you get it the least little bit wrong it messes up the entire top of the cake...so even if you do a great job of repairing the error, the final product still doesn't look flawlessly perfect, which means that Karen is about 95% likely to sue you for ruining the entire reception and causing her to need therapy from the trauma of seeing her. special. day. absolutely and completely destroyed through your sheer ineptitude, and this is also why she's already in couple's therapy and you can go ahead and pay for that too, idiot.
• I evidently have some kind of latent cake-based trauma.
• It's good to have redundant tools on-hand, and a small bucket of acetone. When I shaped my filleting tool I only made one of them because I wasn't sure if I would like the radius that I chose - somewhere around 1/2" or so - but it turned out to be fine, so I just ran with it...but I should have made a second one, so that I didn't have to keep stopping after mixing a batch of filleting compound to clean the hardening stuff from the single tool that I made. It would have been much easier to just drop it in a small acetone bath and pull the other tool out of the acetone, and then get right back to filleting.
• Slow-cure epoxy would be great for filleting; in my 70-degree garage, the medium-speed catalyst gave me about fifteen minutes before it started kicking over, and although that's sorta-kinda-okayish in other situations, it totally changed the way the filleting compound was moving on the plywood surface. Slow-cure and a slightly-stiffer mixture would have been a better option for this application.
• Hand-sanding isn't that awful, but unless you're pedantic it would be better to have an orbital sander with all of the dust collection. Literally all of it. There is no such thing as too much dust collection.

So, yeah...overall: not that bad. There are a few shaping errors, but I think I'll find all of them when I sand the fillets. I'll probably get a small sanding block for that, and pre-emptively salvage my fingers; whatever I can't skim-coat with a second layer of filleting compound will probably be hidden by the texture of the bedliner...because bedliner is very, very good at hiding the minor crimes that have been committed on the surface beneath. Hmmm, it's almost like I planned to screw this part up. Almost.

The fillets cured pretty well, overnight; I had a tiny bit of sag in one corner, but aside from that one spot - quickly remedied with a file - they turned out okay. I did some rough shaping with a scraper and a sanding block along the top edges of the skirts, and then I flipped the whole thing over to start working on the bottom; I need to get back into practice for this kind of work, so I don't especially want to use the finished, visible surface for any of that. Also, there's a lot of work to be done on the bottom; the Total Boat epoxy is seriously thixomotroporific and it can/will display its adoration for escape, given the slightest provocation...which is how I ended up accidentally gluing a leveling shim to the bottom of the sink.

Pictured: Told you I'd screw it up...




To be honest, this wasn't terrible: the PETG popped right off and I barely had any cleanup from it. The rest of the underside, however...

Pictured: That was a different story.




There wasn't a huge degree of height difference between the two skirt pieces, so that joint came out pretty well...but the thickness of that one subframe section on the end was significant; I had to work that down with a scraper until it matched the thickness of the adjacent piece and the end skirt, and then add a tiny bit of thickened epoxy to the edge of the front skirt, shown at the bottom of the photo. I didn't worry about the pile-up of epoxy on the very edge; that'll actually make the next level-and-fill operation a lot easier, because I can just bring the extra epoxy down to the level of the wood and then skim-coat any low areas between the two. Between the scraper and a coarse file, it's quick work. Hopefully the same can be said for all of the screw holes, which actually took quite a bit of filleting compound to fill and level.

Pictured: Carpal tunnel.




Honestly, it looks worse than it is; the silica makes for quick b-sanding, so it was more efficient to just slather the stuff on and work it back down than it would be to try to accurately fill, scrape, level and re-fill every single screw hole and void on the bottom surface. I also don't really have to make this portion of the sink anything other than functional, but since I'm using this as a skill-building project I don't mind the extra effort. In time I'll probably be much more able to just skim-fill holes and voids without leaving a ton of extra compound on the surface, but I'm not displeased with the results thus far; everything has cured correctly and I haven't found any issues with the work that's been completed thus far. So, we'll see how this goes; hopefully this was the last of the major filling operations, and everything from this point forward will be cleanup, shaping and sealing/finishing. I think I have about 50% of the epoxy left, so I'll probably need another quart...but that's Tomorrow Me's problem as well.

Stay tuned.

Ah, the joy of "working time," with active materials. My favorite is Xypex (hydraulic cement). my second favorite is "Hot mud" or the various mixtures of Fast set lite joint compound. 5 min mud tests one's ability to get situated on a ladder with knives in hand for sure. 3rd on my list would be Bondo.

Cake based trauma! I almost landed in that club over my Neice's birthday cake in December. My wife was frazzled and asked for my help, but the frosting was stiff and the cake brand new. I escaped the kitchen without puncture wounds, but there were some tense moments.

You could have simply glued 3 more leveling shims to the corresponding places. It is the bottom after all.

MTGseattle said:

Ah, the joy of "working time," with active materials. My favorite is Xypex (hydraulic cement). my second favorite is "Hot mud" or the various mixtures of Fast set lite joint compound. 5 min mud tests one's ability to get situated on a ladder with knives in hand for sure. 3rd on my list would be Bondo.

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I've worked with hydraulic cement before; it's a pain.

MTGseattle said:

Cake based trauma! I almost landed in that club over my Neice's birthday cake in December. My wife was frazzled and asked for my help, but the frosting was stiff and the cake brand new. I escaped the kitchen without puncture wounds, but there were some tense moments.

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The wife of my previous company's owner had the distinction of being the proprietor of the local cake shop, and somewhat regionally famous for her wedding cakes. I cannot even begin to tell you of the bridezilla horror stories that came out of that place; I was present for more than a few of them, and those people literally give humanity a bad name. And let me tell you: I like cake as much as the next ape, but I honestly do not understand the entitlement that some people exhibit at those - and many other - times.

MTGseattle said:

You could have simply glued 3 more leveling shims to the corresponding places. It is the bottom after all.

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It's like you want me to lose sleep...

On that note, however: I'll definitely have to do a bit more skimming and filling in the low spots. I got a lot of it leveled out, but it still needs attention...so I may work on doing some of that later.

Well, I'm waiting on bushings for that other project and trying to not buy anything else I don't need, so that seems like as good a time as any to kill an entire Friday morning by rectifying all of the accidental epoxigooping that I created a few days ago.

Pictured: I hate myself so much right now.




Honestly, I'm overdramatizing it; I've definitely had worse tasks. Example: when compared to every discussion group meeting I had in my Feminist Deconstruction of Classic British Literature class, hand-sanding silica-filled epoxy is a walk in the park. For seriously, that class was like sanding body filler off the back of my retinas for about seventeen weeks straight; giving myself a transorbital with a cheese grater would have been easier.*

I think that when I'm done with flattening everything I'll have just a bit of refilling to do, and then I can move on to routing and sealing all of the corners and surfaces, respectively. Once that's done I just have to complete the same treatment on the inside of the sink - yay - and then I can finally get to applying some finish on this thing. So, that shouldn't take any longer than the rest of winter, assuming that winter lasts through the sixth week of August. More yay. Stay tuned.

*- And while we're on the subject, I just want to go ahead and say that Bathsheeba Everdene is not - I repeat, not - merely an early-Victorian excuse for a dynamic and empowered heroine within a toxic male culture; she is a dynamic and empowered heroine despite any and all circumstances, and you're still flatly wrong about that, Diane.

[ Intermission Concludes ]

So, yeah, I was on the couch not feeling great for a few days, but I got a bit done both before and afterwards. Most of the work revolved around being exceptionally time-inefficient with the lower surfaces of the sink, but I also sunk a bit of effort into the side/end skirt joints; those were all filled, sanded flush, and squared up in preparation for corner-routing.

Pictured: Pay no attention to the veneer chip in the corner.




Normally I would have filled and filed everything perfectly, but since the corners are all getting a round-over pass with the router I didn't bother with these little chipped areas on the extreme edges; as long as the surface below the corner are flat and smooth - i.e. where the round-over bit's bearing will contact and ride - then everything will work out. At least, that's what I'm assuming will happen; the round-over I chose for this is rather...uh...well, it's rather small.

Pictured: Perceived inadequacy.





So, uh, yeah...about that...



Now, before anyone insults my rather awful efforts at picturery-takery, let me point something out: this is about the best image you could ever ask for...assuming, of course, that you were asking "What does a 1/16" corner round-over route actually look like, in real life?" But you likely weren't asking that, because nobody aside from me is stupid enough to put a 1/16" corner round-over route on anything, at all, ever. And that's because everyone else would have just taken some 100-grit and broken the edges and been done with it, and that would have been fine...but since I have serious issues, I had to do things the hard way, only to learn that they still have to be re-done. To explain...

Initially, my thought was to match the corner radii of the dry sink to those on the adjacent enlarger table; those radii are actually 2mm, because that's the thickness of the edge-banding on those tables. However, metric router bits can be in short supply if you're in the US or Liberia, so I was stuck choosing between 1/16" and 1/8" radii; the closest-possible 5/64" radius doesn't even exist...but since I'm not that pedantic in the first place, I just went with the 1/16" and hoped that it would be good. Long story short: it isn't. I had my reservations about an edge radius that tight in the first place, but after seeing it and feeling it I know it's not going to work; it's just too small. And it's not user-friendly; the edge still feel sharp-ish and severe at 1/16". Solution: re-route everything to 1/8" and see how it looks...but since I don't have a 1/8" bit that I want to use on this, I detoured away from the edge-work into finishing the remainder of the underside and starting the layout for the desk frame.

Pictured: Very nice.




I'm mostly-happy with how the frame fits the underside; there's one tiny little error that took three minutes of work to rectify - bonus points if anyone can spot it - but aside from that, it all went as planned. I will likely enlarge the mounting holes that are in the end brackets, because there's a bit of variance in their locations and they aren't much bigger than the 1/4-20 threaded inserts that will secure them to the sink base. In fact, I'd say the room for locational error is somewhere between "minimal" and "yeah, good luck with that" at current; the screws are about .241" across the threads and the frame's mounting holes are .275".

Pictured: Who designed this thing? Ugh!




After the locations were marked, I decided to be slightly smart about things and drill the mounting holes with a guide; I'm so good at drilling holes askew that I can even do it with a drill press, if I'm trying hard enough. Thus, I took a few minutes and made a quick drilling guide on the Prusa, which was mostly an excuse to test out some new layer properties in ABS and also play with the Loft tool in Fusion. Also, yes: this means that I spent three days filling and sealing all of those surfaces, only to then proceed with drilling holes in it.

Pictured: Brilliant strategy, Napoleon.




If that hole should happen to look too big for the threaded insert, that's because it is: more on that in a minute. For now, let's take a look at something I noticed when I was sinking these: a cross-section of the epoxy joint, which - having now seen it - I am not worried about in the least.

Pictured: Sexy.




In case it's not clear: the thin, light line being bisected by the drill bore is the surface veneer of the end skirt - about .008" thick, right there - and the darker line adjacent is the epoxy joint; that joint varies from .015" to almost .030" in places, because cutting all of this with a baby circular saw isn't the most accurate method...but I'm not complaining. The drill bores are .375" to .625" deep (depending on location) and the epoxy is a solid, gapless line in every one of them...so that part of this project is no longer anything to worry about.

Also, about the hole sizing: here's the explanation for why they're so big.

Pictured: The "explanation", rather...




You may have questions. If so, here are some of the answers:

• The hole diameter is 12.5mm. Why? Well, the 7/16" bit wasn't quite big enough and the 1/2" bit was a little too big, and both of them needed sharpening...so 12.5mm did the trick.
• Yes, the insert is in the hole upside-down; since the bore is larger than the largest diameter of the threads I didn't need to leave the drive flange of the insert exposed, because it's not being screwed into the hole.
• The insert isn't being screwed into the hole mostly because I don't like screwing large-diameter coarse threads into plywood of questionable provenance. Instead, the insert will be epoxied into place; there's just enough space between the threads and the edges of the bore to let a nice amount of epoxy flow into the void, which should lock the insert into place and also seal any exposed cores.
• I'm not worried about the epoxy flowing under the insert and into the central threads of the insert; when I slipped the inserts into the holes I used a bit of epoxy putty in the bottom of each hole to suspend the inserts at the correct height. After a bit of pushing and prodding and accidental bread-tricking inside the threaded bore of the insert by way of a handy roll-pin punch, I had a solid bed of epoxy under each insert that the epoxy shouldn't be able to flow into; we'll find out later whether or not that's true, I suppose.
• After the inserts are fully epoxied into place, I'll take a file and a sanding block to them and work the surface back to flush. Hopefully, that won't take long; I only left a few hundredth's-worth of brass above the level of the plywood.

And that's where we are for now; time for me to go mix some epoxy and probably cause a huge cock-up that I have to figure out how to remedy, later.

And against all odds, I don't actually have to repair anything.

Pictured: Why can't everything else just go according to plan?




Pay no attention to the ridiculous amount of debris in the photo; metal-flavored grinding was happening in an adjacent area. But yeah, these worked reasonably well...so now, all I need to do is re-route the outside edges on the bottom, block the opening in the threaded inserts, and I'll be ready to epoxy the bottom and get that out of the way.

Got a few things done in the last few days, despite the chaos of...well, everything that I'm always trying to do. Topping that list are the newly-re-routed edges that are SO much nicer than the old ones, and SO not either of the radii that I was considering.

Not Pictured: 1/16" or 1/8" curves.




That...well, that's a 1/4" round-over. And that's exactly not the radius that I wanted to use, but after testing a 1/8" round-over and finding that it was still too sharp for my taste - and for my forearms - I decided to just go all-in and take the edges down to the largest radius that I could create without making this thing look like a product of the early-2000's automotive design industry. Was that a good decision? Honestly, I don't know; I don't particularly like the way these corners look, but they'll be more durable, more comfortable, and a hell of a lot more friendly for the bedliner that's going to be applied in a few days weeks. I was admittedly concerned about how the tiny 1/16" radius was going to handle a finish layer; the 1/8" option would likely have been perfectly fine, but neither will be as friendly as the larger 1/4" that I've used.

Regarding the cutting of the larger round-over: I didn't have any serious issues, but I did experience one rather large layer blowout, which is a phrase that here means "I actually experienced two rather large layer blowouts, and they were so severe that I didn't even want to photograph them; also, they weren't my fault." As it turns out, there was a very porous patch within one of the surface plies, and I managed to bisect it when I did the original layout; cutting presented no difficulties, but routing was another matter entirely. This being said: filleting compound solved the problem entirely. I dug out the splinters and shards of the broken layers, mixed up a splash of resin with a ton of silica in it, and slathered it in; after that I just blocked and flattened the area and re-routed those sections. Problem solved, that; while I was at it, I created a few fillets in the interior corners and smoothed those up as well.

Pictured: Great success!




After that was done, I used some leftover epoxy putty for building up and shaping the three-way corners at the base of each interior fillet, and then rolled a coat of epoxy over the entire thing.

Pictured: Finally...some actual finishing.




The roller of choice for this was a 4" foam cabinet roller, and it did really well...except for the part where a chunk of the roller delaminated and proceeded to turn itself into tiny snowballs that I then had to pick out of the epoxy. I'll likely add a second coat to a couple of areas where the resin absorbed heavily, and which look almost dry; I think that's the plywood's way of telling me that it would like a refill in those specific spots. Once that work is done I can give it a light sanding and then locate and install some threaded inserts for the height-controller-button-pad-thingy; I would have installed those before now, but since I couldn't find any that were the correct size I had to order some. When those are installed, this can all be flipped over, installed on a leg set...and yeah, then we can get started on the interior.

Stay tuned.