CNC Cabinetry - Designing and choosing knock down connectors

Fabien · August 25, 2023, 1:44pm

I’m in the process of making a large bespoke shelf for my office

The cabinets would be made out of 16/18mm thick agglomerate boards (depending on what I can find/buy)
The depth of the cabinet should be around 30cm
I’m not really willing to cut everything out of a single sheet/panel, so I’ll probably go with pre-cut 30cm wide tablets and just cut the length according to my needs

As I want some of the tablets to be adjustable, and I may add doors at a later point, I would like this cabinets to follow System 32
This is an ideal case for using the LR3 for cutting those numerous holes on the sides (had to do it once by hand with a jig, and it gets old very quick >_<)

So, while the stock is setup on the CNC, why not grab this occasion to locate and drill all features? Like fittings and such…

But I still have a few questions and would love some feedback/advice on this from the community

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1 - Designing the cabinets
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Right now, I’ve made a rough sketch of the cabinets I want (see picture above)

I also made a parametric Fusion360 design that takes a few inputs and creates the sides and top/bottom tablets following System32 specifications

Questions:

Are there better alternatives than just plain Fusion360 out there?

I’ve seen a few specialized commercial products, but they’re all extremely costly for a hobbyist (we’re lookuking at 500$/month liscences…)
I’ve also seen a FreeCAD macro for system32 but couldn’t get it to work properly… I’m not very sold on freecad anyway

Don’t know if there’s any free-ish addon or software I could use?

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2 - Joinery and hardware choice
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The next question is “How do I assemble the panels?”

Traditionaly, I’ve been using a doweling jig and 8mm dowels for this, plus some glue to hold everything together…

I’d like the cabinets to be easily assembled/disassembled if need be, so I’m thinking of using some kind of assembly hardware instead of glue

Here are the options I’ve seen so far:

Pocket holes

Pros:

Cheap
Cons:
Fiddly (I have a jig for this, never really liked it…)
Totally manual operation,

Note: I’ve seen a video about CNC-cutting pocket holes, has anyone tried this?

Rastex/Minifix connectors

image1000×634 48.6 KB

Price: 0.60€/piece - need 18
Pros:

Easy to buy (hardware store)
Good strength
Accomodates different thickness of stock
Cons:
Needs a manual drilling operation on the side of the tablet, not fully cnc cut.

Expando / Quickfix cam-style connectors

Boîtiers excentriques VB 361000×1000 119 KB

Price: 0.86€/piece - need 18
Pros:

Easy to buy (hardware store)
Only requires surface milling operations
Integrates with System32 holes
Cons:
Concerns about strength (justified?)
Only fits 16mm and 19mm boards. (the ones I can easily buy are 18mm thick)

Cabineo

image640×640 53 KB

Price: 0.18€/piece… but you need to buy in bulk, either115€ starter kit (you need a specific screwdriver) for 80 pieces or 190€ for 500/pieces
Pros:

Strength
Only requires surface milling operations
Integrates with System32 holes
Cons:
Price
Not easy to buy (bulk packaging, and specialized profesionnal distribution)

Questions:

Right now, I’m leaning toward the Expando fittings as they offer an interesting mix between price, automation capability and availability
Are there any other fittings that would fit the bill?
Any other way to assemble I wouldn’t have thought of (keyhole maybe?)

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3 - Cutting/Machining
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As previously stated, I’ll probably cut those out of 250x30x18mm tablets
They’re more readily available, and easier to handle for me
Also, they come already fitted with 3 sideed edge banding

How would you go about machining this so that everything is square and true?
I was thinking about cutting an “L-shaped” form on one end of the spoilboard, and then reference the tablet to this feature

Anyone already did similar work and could provide some advices?

As always, thanks to every member of the community who take the time to read and respond to this
The goal is to be able to conclude this project with success, but also share the knowledge and give ideas to others, so, feel free to elaborate on the subject

niget2002 · August 25, 2023, 3:16pm

Just my opinion, but pocket hole screws should only be used for holding wood together while glue dries. I’ve had projects start to wobble if only held by the screws. Maybe I didn’t use enough.

I can’t comment on the other fastener options, but you should have at least the top, bottom, and one shelf permanently attached to both sides. This will keep the sides from bowing out. The rest of the shelves can be adjustable. You shouldn’t rely on just the top and bottom to keep the shelf together.

brenavich980 · August 25, 2023, 4:07pm

A small microwave stand was one of my first projects for my LR2 back in the day. I don’t use the LR2 for that but I have done a lot of case work by hand and with machines. You can get as fancy as you want but here’s how a cheap bastard like me would approach it.

That’s like a personal preference right? There are other things out there and I’ve looked at a few, but really if you know how to use it then why switch? You might need to dive a little bit deeper into the features but it’s better than learning a new program or workflow.

Pocket screws are only really useful for solid wood and potentially plywood IMO. In your picture of pocket screws you see those screws are biting into cross grain. Press board really doesn’t have a strong core to bite into and might tear out if you accidently rack the assembly.

What I would do for the carcass is get furniture screw nuts the for the top uprights and use countersunk bolts for the top. You could get “stickers” to cover the holes if you like but no one would ever see them.

Are you attaching it to the wall? I would consider it since all the strength in the design relies on the uprights being plumb. Any racking could be catastrophic. To attach the uprights to the wall I’d just design and 3D print (that way you can make them as small and inconspicuous as possible) small screw blocks that attach to both the upright and the wall. Maybe a set of 3-4 on each upright.

Side note: The biggest use I’ve found for a 3D printer is making custom hardware for furniture projects. You will save SO MUCH money by designing and printing custom hardware solutions rather than trying to work around someone else’s expensive product.

Then I would just use regular steel pins and dado slots on the bottom of each shelf so the pins are hidden when installed. Unless you plan on putting a TON of weight on each shelf this should be plenty of support.

Speaking of which, if you know you’re going to have shelves that will not be moved (which you may want to consider) housing dados are one of the strongest and easiest joints there is. Absolutely recommend that method for any stationary shelves.

Exactly. But instead of a solid form, use dogs. Essentially sequential holes in that “L” pattern and pins that fit tight into them. 3D print the pins or use dowels. That way you will have registration points but they won’t collect saw dust in the corners and screw up your alignment. Just have to make sure your CNC head won’t crash into the pins.

Olivier · August 25, 2023, 4:30pm

Well although I can use the LR3, in some cases curring the holes with a jig is faster…

I am sure there are, but will depend if you are willing to learn them, and how fast your learning goes. Personally I designed all my cabinets using f360 as it was quick and easy to do so.

No regular dowels? I know you should glue them, but in my cabinets I didn’t do that, without issues (obviously I use dowel / screw combo)
If you are willing to use the cnc, you can predrill the dowel &screw holes on your panels. In that case you only need to use a jig for the sides the cnc cannot reach.

I must confess that my biggest cabinets have been sawn and cnc’d at a wood company. They have all the tools they need and I only needed to provide my cad files.

Fabien · August 25, 2023, 4:51pm

Nah, it’s not just you, I’m feeling the same

Valid point, so I guess we’re ruling out pocket screws altogether… not that I will miss them…

Yes sir! They will be pretty much right against the wall though, so I don’t think I’ll need spacers

I only drawn the top and bottom but I plan on having the middle shelf fixed too, yes
With the expando fitting, the fixed tablet can be set anywhere, so that would be pretty easy

The question was more about Addons that would help designing System32 compliant furniture, or help integrate specific fasteners

That’s a pro-tip here! Noted!

That’s kind of what I was doing on the LR2 though, it was installed on a festool MFT3 bench, and I used some dog holes to home, setup and square the work
Probably will do something similar with the LR3 too

I was trying to see if the LR3 could speed up my process a bit
This one is already a bit big, and I may have two more similar cabinets to do in a near future

i’ve already built a massive dressing with dowels in MDF, and it’s been a long process, not really hard, but very prone to error when it’s the billon-th hole you’re locating and drilling

Thought about that, that would be a nice way to do the “minifix” assembly…
But I’m under the impression I’d have better luck drilling both corresponding holes with the same jig, rather than trying to make the jig match the CNC

brenavich980 · August 25, 2023, 6:37pm

Looks like you know what you’re doing so I’ll give you this advice which you might already adhere to: Cut and build in stages. Don’t design and cut everything at once. That’s a burden for production environments.

You’ll be able to make adjustments, come up with better designs, and make something truly unique. Even if you planned on it being utilitarian, you’ll like it more in the end if it’s special to the space.

Olivier · August 25, 2023, 6:55pm

I totally get that. That’s why you have a cnc at home

Lol!

I know nothing about the minifix, but for dowels I use these two tools:

https://www.amazon.com.be/-/en/kajkey®-Pieces-Centring-Drilling-Positioning/dp/B09H279GYB/ref=asc_df_B09H279GYB/?tag=begogshpadsp-21&linkCode=df0&hvadid=633260319051&hvpos=&hvnetw=g&hvrand=4444647594425356668&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9040052&hvtargid=pla-1461810732453&psc=1&gclid=CjwKCAjwoqGnBhAcEiwAwK-OkUMv3kRZxi0eZ4ef3_4OvN0AnpDZfPqS8jXnwsqoMSqxzNCvIM6eRhoC9_IQAvD_BwE

Both help a lot in matching the holes. Althoug I feel like the centering pins are a bit less precise to my liking, but faster than the jig where you’d need to align the other panel first.

Maybe some mod for the lr3 could be cool, so you could put the panels on their side and drill according to the cad design;)

SupraGuy · August 25, 2023, 7:42pm

Pretty sure Jeffeb3 designed his table so exactly that cound be done. I can do it with my table, too, so long as the pieces aren’t too tall… I set mine up so that I can park the router off of the edge of the spoilboard, which also lets me use that open area. (I did that because I tbought Jeff’s idea was a good one.)

Fabien · August 25, 2023, 9:11pm

Dude! I have the whole pokemon collection

Started with this one… very hard and cumbersome to use…
https://www.wolfcraft.com/products/wolfcraft/en/EUR/Products/Wood-Joints/Dowel-Jointers/Universal-Dowelling-Set/p/P_3750

Then I bought this one…

Better, smaller, but it’s slow and tedious on large builds…
But as long as you only have a few dowels to install, or do this very occasionaly, it’s pretty good…
It’s the same as yours, but with some accessories already included like the centering pins…
The depth gauge is a bit different too…

I made some mods to mine so that it’s a bit quicker and easier to use
Some of them can be used on your model too if you want to check it out
https://www.printables.com/fr/model/191901-wolfcraft-dowel-master-jig-upgrades

At some point, I also bought the “undercover jig” after watching too much youtube videos
https://www.wolfcraft.com/products/wolfcraft/en/EUR/Products/Wood-Joints/Dowel-Jointers/Undercover-Jig-Set/p/P_4642

As I said, I was never really convinced by this one… it’s fiddly, it’s not really sturdy once assembled, it’s a pain to find the correct screws (or you can buy the original ones, if you find them, at gold price)

Finally, I bought the “ruler” one
https://www.wolfcraft.com/products/wolfcraft/en/EUR/Products/Attachments-for-Machines/Drill-Guides/Dowelling-jig/p/P_4650

That’s pretty much the best jig of them all
It’s very efficient and easy to use, you can do a lot of dowels in a row, it’s quite easy to use in the middle of a panel, and it doubles as a system32 jig for shelf pins (although it’s a bit tedious to drill 200+ holes manually…)

I also made some mods for this one…
One allows me to reference the jig from previous holes I drilled, should the workpiece length exceed the ruler’s length
https://www.printables.com/fr/model/191906-centering-tool-for-wolfcraft-4650-doweling-jig-rul

And the other one is more of a “niche” need: I reused the shaft of the wolfcraft jig to 3D print an angled doweling jig

This jig allowed me to join multiple strips cut witha corresponding angle, and make a small arch for the top of the dressing

So, I guess you could say “I know my dowels” somehow

Fabien · August 25, 2023, 9:17pm

Back to the subject…

I made a quick test-cut for the “expando-style” fixings

I can confirm the link is pretty sturdy, and the fact that you can just"click" them together by a quarter turn of a screw is just great!

I need to dial in those tolerances though, as the wood tends to blow out, and the hardware is not quite flush with the surface…

Also, I used fixings meant for 16mm boards on 18mm boards, and it worked just fine, I will need to drill specific holes for the fixings of the top shelf if I want them to be flush though…

bitingmidge · August 25, 2023, 9:54pm

The expandos look good for the job.

My question though is: “just how knock down do you need?”

I would tend to make the modules as permanent shells (screwed) , and just use the knock down fittings where you think you need to break the cabinets up in future.

Fabien · August 25, 2023, 9:58pm

I think I will use them on the fixed shelves of each module
So that’s 4 per fixed shelf, 3 fixed shelves per module, 12 fixings per module
I have 3 modules, 36 fixings…

They come in pack of 8, I need 5 packs, 6.5€ per pack, that’s 32.5€ in fixings, not too bad I guess

Part of the appeal is to be able to just assemble the boards in the destination room rather than messing around with screws and glue, straps, clamps and so on…

With these I just have to slot the boards in, turn a screw, and they’re clamped square

Also, there are sides I don’t want visible screws on

Olivier · August 26, 2023, 10:27am

We have found the master of dowels

It would make sense to add them on the top one and bottom one. That way you can put them out of sight, and for all shelves in between just some regular pins.

jeffeb3 · August 27, 2023, 3:37am

I don’t want to be the wet blanket. But have you considered the ikea Sektion cabinets? The carcasses and shelves are very cheap. They have figured out exactly how to mount them to almost any wall in a secure way. They have a system for adding in tons of drawers, doors, and shelves. The closet stuff is neat too (pax). I haven’t been able to make anything as cheap and as flexible as they have. If nothing else, they might give you an idea of how far a span can go without support or how many fasteners you need, etc. The drawers and door hardware really can add a lot of expense. But the carcasses and shelves are cheaper than raw materials.

Your walls must be flatter than mine. The spacers and special adjustment hardware is to match the wild construction walls, not to correct for my poor cabinetry skills.

Fabien · August 27, 2023, 7:38am

I just finished asembling a Pax dressing in the bedroom next to this
Pretty impressive how they optimized the manufacturing and assembly process on the new ones… they just unfold with the back already attached, and there’s no more screws, just keyholes to attach the fittings

I still need to add two custom cabinets on top and on the side to fill the space

But for this one I need it to be the exact size so it’s quicker to just make it rather than adapting existing cabinets (we had 2 Billy at this spot previously but they’re not tall enough and 2 of them are too wide for the space whereas a single one is too narrow)

Concerning accessories/hardware, the system32 should ensure compatibility with hinges and rails, although I’d still need to customize the door/drawer width

Concerning the walls, the two I will be leaning on are recently re-built drywalls and they’re pretty plumb
I’ll probably need spacers but more like shims than real thick 3d printed ones
I tend to use flooring shims for this (small wood wedges)
One more constraint is that I cannot use the back wall as it covers a concealed sliding door

Price-wise, this one will set me back around 120€ in raw material and 35-50€ in hardware

Buying existing cabinets would cost around 160-200€ I think, but would still require some hacking to fit exactly

Ikea prices have gone crazy too
A 80x230 Billy cabinet with shelves is already 90€ o_O
The pax dressing I just built was jus a bit larger than the span I’m trying to cover hère( 250x230) and around 700€, very few accessories and no doors…

Tokoloshe · August 27, 2023, 6:55pm

I’ve got that one, too. They sold it for like, 30% at the local Hornbach.

I’ve had this one on my wish list for ages:
https://www.amazon.de/Kreg-Pocket-Hole-Jig-720PRO/dp/B08Z47NL46/

Fabien · August 28, 2023, 9:29pm

In the meantime I started yet another side-project, for the opposite wall… and it’s a bit of the complete opposite to this one…

small floating shelf, hard wood, kinda designer-friendly, no connectors at all

I already made a few fitting tests and I must say I’m pretty pleased

All made from a leftover of natural oak flooring I had laying around
Quite a bit of effort went into making sure I could squeeze 2 parts on the width of the plank

Will post in the appropriate section when I’m done

Fabien · April 16, 2024, 6:02pm

Epilogue : in the end I just used plain old woodworking tools and a simple jig for Minifix / Rastex connectors

It only works for 18mm stock but it’s fast and convenient, and only costs 18€, which is pretty cheap

I also remodeled my desk in the process

I was feeling frustrated not having anything CNC cut on this project through, so I set out to laser cut some cover plates for my cable management system

Fabien · April 21, 2024, 9:48pm

I mostly finished the second cabinet yesterday, nothing fancy…
Today I had to fix the shelf in-between the two cabinets above the door.

As I couldn’t move the two cabinets apart any further, there was simply no way to use dowels (or rastex/minifix fittings) here

And then, I just remembered I had some of those VB34 connectors left, and they just happen to let me drop the joining shelf in place from above or under without any extra space

I changed a few parameters in the design, drilled some positionning 8mm holes for wooden dowels on the table (following @brenavich980’s great advice), and there we go…

The program only drills two pockets on one side per run, once cut, I just have to flip the board and re-run it
This would theorically let me cut those pocket on any shelf whatever the length, but I just have those 4 holes to cut, so…

As the mating part is already installed and it only needs a well-placed 5mm hole, I just designed and printed a small positioning jig

(sorry about this blurred one :/)

Then I lifted the shelf up in-between the two cabinets and locked the cams

The fit is pretty much perfect

Note: the joining shelf will receive some supporting hooks later on as it pretty wobbly in the middle right now…

In the end, although I didn’t use the CNC to cut everything, the LR3 once-again proved an efficient woodworking tool among other more “conventional” ones

The combination of the cnc-cut pockets and manually drilled mating hole works very nicely, and it’s pretty easy to obtain pricise and repeatable results with this method, without spending hours in machining

Had I known this earlier, I’d probably have gone with the VB34 fittings all around… maybe next time

Britt · April 21, 2024, 10:39pm

That turned out great.