Instructables
After renovating the bathroom, I needed a new bathroom cabinet that had some storage space underneath the wash basin and some extra storage space to the right of the basin. However, due to the layout of the bathroom, the part where the wash basin is located should preferrably be round (so you don't hurt yourself at sharp corners when you walk through) and the part to the right should be very shallow (max 12 cm).

Since I couldn't find anything like this, me and my dad decided to build one ourself.

This instructable does not include the complete instructions for the cabinet, but only for the part with the rounded doors since that is the most difficult part.
 
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Step 1: Make a mold

Picture of Make a mold
To make curved doors, start by making two identical molds out of 18 mm medium-density fiberboard (MDF). For this part, we forgot to take pictures, but the process is fairly simple:
1. Nail 2 pieces of MDF together, so both molds will be exactly the same. Make sure the nails stick out a little so you can easily remove them later on.
2. Cut them to a rectangle that is much longer and a little wider than you need.
3. On one side of the rectangle, draw a half circle. Make sure the mold will still be much wider than you really need. Draw a center line on the molds. We will need this later on for alignment.
4. Cut out the half circle a little wider than you need. You should now end up with a mold that has an approximate circle that is a little too wide.
5. Shave the mold on all 4 sides to exactly the curvature you need. Do make sure that it keeps quite a bit longer than what you actually need.
6. Remove the nails to separate the two molds. You should now have to identical molds with exactly the right curvature.
7. Nail the two molds onto a third piece of wood, making an upside-down pi shape. The two molds should be spaced apart so that they are placed at 1/4 and 3/4 of the length of the piece of wood you want to bend.

Note: the molds can be re-used later on for top and bottom part (or interior shelf). The time it takes to make these two identical is thus not only for making a one-time only mold but also for making other parts of the cabinet.
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thayes411 days ago

wow, this form of a curved wood surface is exactly was I was looking for. Took a lot of misses before I hit this. Thanks a ton for sharing!

josdevassy10 months ago
perfect job
josdevassy10 months ago
good job
icooper210 months ago
That is friggin awesome!! Excellent share. I will now try and build one!
AngryRedhead10 months ago
Beautiful!
emerson.john10 months ago
This is simply an excellent finished product. Very good job!
Tinworm10 months ago
This is really excellent. Thanks very much for a great set of instructions. I have been trying to find a way to do exactly the same, and now I can.

Thank you
OTP110 months ago
Excellent, thank you for you time to show us all, and you skills, great job
mpmansell10 months ago
Thanks for sharing such a flexible technique. To get a really smooth finish, I would suggest filling the kerfs of the outer layer with resin before forming it over the inner. That way, when they are set, it would be possible to sand the outer smooth without having to worry about sanding through the kerfs themselves. any voids after sanding could be filled with resin, or a paste made from resin and sawdust, and then shaped when set.
staida10 months ago
I have done this before by layering laminate sheets over the form and building up to final dimensions. If you're using a good glue, this can be done even with something like balsa and produce very strong results. I don't know that I would have ever thought of this nor that I would still do it having seen it but I'm sure it cured 100 times faster than mine, only required the lower half of the form (not a press) and it does look very good. Excellent work!
el-Raza (author)  staida10 months ago
I thought if laminating as well. Nice aspects of laminating would be that there would not be any 'slots' and that you could have very nice looking wood on the outside. But as you mention, it also requires having a press which was a big drawback for us.

I was also not sure if laminating would work on such large surfaces (~ 90 x 160 cm). Do you have any ideas about that?
tomaschurizoe10 months ago
You should mention how you managed to make the cabinet attachments to the wall. Being that you show it in a floating mount I imagine there is a lot of weight riding on the attachments. I believe MDF is fairly brittle at the edges. Very nice instructables. Thank you.
el-Raza (author)  tomaschurizoe10 months ago
Oh, we just mounted 2 very sturdy and long brackets to the wall. Sorry I don't have any picture of that.

We recycled the to half-circular parts of the mold as bottom and inner piece of the cabinet. The inner piece is just above the doors and is glued and nailed to the curved outside. This inner piece rests on the brackets and carries all the weight. I hope this description is clear, as I don't have any pictures.

It all seems very sturdy, even if I fill up the basin with water and put some of my own weight on it.
lsymms10 months ago
how did you cut such straight lines on such a large curved piece? I'm guessing it wasn't a gigantic band saw. The cut at the top of the doors seems doable with a small circular saw, but the vertical cuts down the middle and side would probably need jigs for to keep the blade perpendicular.
el-Raza (author)  lsymms10 months ago
Just a plain old hand saw (not sure which one, probably a carpenters crosscut saw). I have to admit that my dad made these cuts as he is a bit better at it than I am, but which such saws it's not very difficult to keep straight.

The only part where we used electric tools was a circular saw for making the kerfs, since you need very good control over the depth.
DJCoopes10 months ago
REALLY COOL!!!!!!!!!!!!!!!!!!!! I want one for my bedroom as a cubby door underneath my bunk bed.
el-Raza (author)  DJCoopes10 months ago
Not sure what you mean, but as long as you want it curved in only 1 dimension (so not spherical or something like that) and not too sharp corners, it should be possible with this method.
Deltic10 months ago
Well done on a great looking final product. I would recommend purchasing outdoor grade MDF if you are going to be using it in a damp environment. You could save time by buying "bendable" MDF which already has the slots in, also by gluing the two sheets together, cutting out the doors & THEN using your sawdust / glue mixture to fill in only the visible gaps left.
When painting your 1st coat using a 50/50 mix of household emulsion paint & water should prime the surface nicely to stop further soakage.
MDF can also be bent quite happily by thoroughly soaking in water then allowing to dry whilst clamped in position, however I don't know what sort of deformation this method might cause.
el-Raza (author)  Deltic10 months ago
I found out about the bendable MDF with the slots just a few hours after I cut them. It was no big deal though, since cutting the slots was only about 1 hour of work and the bendable MDF was ridiculously expensive and hard to get.
Alderin10 months ago
Very nice work!

I was a little confused about the molds until the pictures of the kerfed MDF laying on them. A picture of the finished mold rig would be helpful in step 2.

I love the glue-and-sawdust paste idea. Since that is basically what MDF is in the first place, it should end up re-making the MDF solid in the kerfs. Wish I had thought of that. Thanks!
el-Raza (author)  Alderin10 months ago
Thanks for reminding me that a picture of the mold was missing. I've added it now.

The idea of glue-and-sawdust paste came from one of the websites where I've seen this technique. I was really surprised both how flexible the MDF became and how sturdy and strong it became once it was set in place and the paste had dried.
estructor10 months ago
Nicely done. I've built curved doors for a vanity; out of cedar that was finished clear. For that, I coopered staves together. Technique involved ripping many individual (book-matched from same stock) staves to bevel their edges at correct angle to meet desired curvature. Using sector division, desired arc is drawn on a paper plan, then divided with equal marks along the line. Correct bevel can be determined then. It was a fun project. --Yours looks great!
el-Raza (author)  estructor10 months ago
Wow! Your method sounds pretty complicated and tough! Would love to see a picture of it. I'm very curious how the cedar turned out.
strship4710 months ago
Really nice job,I'm thinking of using the same technique to build a
sub-woofer about the same size.thanks
Spokehedz10 months ago
Oh my god, my dream of a Portal 2 bathroom is now a possibility.
Exactly what I thought when I first saw it.
AJMansfield10 months ago
That looks like something that would fit right in with an Aperture Science theme.
DJCoopes10 months ago
By the way, Will it work?
zeroaxe10 months ago
Love the work. Love the result. Good job!

It just occurred to me. with this type of build, 'funky' doors can be cut-out. Don't have to follow/cut straight lines. That should make for an even better futuristic, teleportal cabinet! ;)
Sailingsoul10 months ago
Great job with the cabinet and with the instructable. Thanks
clazman10 months ago
Great design, Great job.

This is an age-old procedure for bending panels, but nicely done. Especially like your idea of hiding the kerf via the sandwich method.

As for the larger than desired gaps why not just glue a veneer to the edges?

Also, your finish procedure is exemplary. Using the water based paint for the primer coat and the more durable lacquer for the top coat.

Not sure if I like the hinge mounting blocks. I might have made them a little differently to distribute the loads. But, that might be unnecessary for such light weight doors.

A well thought out project to be proud of and enjoy!

Oh, exposed plumbing is nice it it well done.
EvilDaveCanada10 months ago
I didn't want this to sound like an ad BUT:

To make great circles for templates, check out Rockwell's semi-new 5.5-A Multi purpose Saw Model #RK732. It can be found in the major Canadian DIY stores for under $200 CAN. There is also a great YouTube video on how to cut circles on a table circular saw. The Rockwell saw is really just an upside down jigsaw that works like a band-saw that you can hang on the wall when you are not using it. It is on the Christmas list so I can't buy one until Boxing day if I don't get one on the 25th.

The Idea on making curved wooden panels is great but the real trick is getting the round template in the size you want. This instructable is a great example on how to make what you want in the size you want with not having to just buy what ever size the 'big' manufacturers feel like making.
tmallos10 months ago
Fantastic! Many, many applications for this. Thank you for sharing!
ArizonaSRMC10 months ago
I know what I am doing this weekend!!!!
spikec10 months ago
Way cool, thanks for sharing!
B00mrang10 months ago
This looks really good ! I did not know this technique to curve MDF. I suddenly have a lot more respect for this material !
zenderon10 months ago
That's Really a good job, loved the way you did the double skin :)
ledshed10 months ago
Nicely done!
Bettybstt10 months ago
Beautiful work! What a great idea for a free-standing sink - I don't really care for the 'plumbing hanging out' look, this would fix it in style. Great instructable.
Alderin Bettybstt10 months ago
It is a very rare occasion that I want my plumbing hanging out, :-)
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