MDF Homemade Doors Bowing

[slennon]

Hi
I’ve made a bunch of MDF shaker style (kind of) doors from MDF based on the idea in the post below.
mdf-doors-t28119.html
I’m a little concerned that the doors show a slight bend towards the front. Its only about a 1mm or so and I don’t think it is going to be a problem in the hanging, unless of course it gets worse.
Part of the problem could have been that the supplier gave me a lot of old off-cuts in the cut sizes I ordered. He was very cheap so I didn’t argue.
I’m spraying them and drying them on a rack racking, as in the attached PIC. They are racked face up, on the rack and I’m wondering if that is part of the problem or might add to the problem? I avoided water based paints and undercoated in a shellac primer with the topcoat of oil based eggshell.
There are a good few doors in it and a lot of hours have gone into the making and panting. So would be pretty disappointed if they buckled badly when hung. Although there is probably not much I can do except proceed and hope for the best.
Would anyone have any thoughts or have seen this type of problem before and have any insights?
Many thanks
Simon

[dewaltdisney]

MDF is prone to sag depending on how it is stored. Propped against a wall it will develop a curve and it might be that some of the offcuts recycled into your order might have got the bends. The other issue is the racking system that you have built may well introduced sag as the middles are unsupported.

Do not worry it is usually easy to correct by laying the doors concerned on a flat surface curved side up and putting a weight on it. However, if you stuck the edge strips on to a curved board then you may well have fixed the curve in position. It is not the end of the world to knock out a replacement if you have to. I made a set of doors made up of poplar frames with a birch faced ply panel and one of those turned into a banana for no apparent reason. It just happens.

Good effort by the way and I would like to see the finished job pics

DWD

[big-all]

assuming you have only finished one face
get the other one finished to stabilize the door

if the thinner bits where glued on with higher moisture content they could cause pull as they dry that you wont get rid off but will hopefully stay minimum

[slennon]

OK thank you gentlemen that useful.

Ive actually finished them all round and tried to keep it a fairly even coat. Was toying with the idea of putting an extra coat on the back to provid a bit of pull in the opposite direction. Not sure the effort would pay off though.

Ill try just getting them on the flat for a few days before hanging them as suggested....

Will get some pics up when they are hung. Hopeully will get onto that next week...

SL

[mailee]

I too have had that problem with MDF doors but as has been stated by Big al turn them up the other way for a while and they should straighten. Your drying rack isn't helping either.

[slennon]

Yes they definitely have a tendency to sag when sitting on the rack. They relax back a bit when they come down...

I must say I totally underestimated the amount of time the oil based paints take to dry. The doors painted Tuesday night and are still a tad tacky this morning Thursday. I doubt I can sand them for final coat tonight. Must be the temperature is all I can think. Summer or not its still only around 12C during the day here at the moment.

[slennon]

Hi All

Thanks again for the advice. Ive gotten Phase 1 fairly well completed now. The doors did straighten out well when left flat for a bit. Some slight bows remain but they seem to be stable and have been hanging for a couple of weeks now.

Just got the worktops down and have posted a few before and after pics below. Still to do the plinths and another few doors for the oven and larder units....

Thanks again
S

[big-all]

excellent job --------------
















----------shame you put the old doors back on

stunning job well done

[dewaltdisney]

Well done, you made a good job of that. A tricky little bit in the corner with the extractor hood that works well. Just shows what you can do with a bit of patience, it is the painting that is the worst bit but once you get into a rhythm it is not too bad. MDF is a pain to work with but it does the job.



DWD

[slennon]

Yes the painting was a lot of work for sure. Four coats sparyed at about 2.5 to 3 hours per coat. Sanding and edge sealing on top of that.

The corner unit was fun to design and make. I used google sketch up to model it and then could pull the cutting list and exact sizes off it for the angles and odd shapes. It gives a great feel for how the finished product will work. Pic of the model below too...

[southwood3]

I'd be really pleased with myself if I'd achieved that - very impressive. Are the door and drawer 'panels' separate pieces of thinner MDF or are the grooves routed into the panel?

[slennon]

Yes the drawers under the hob were an afterthought, as the oven was originally supposed to go there. Its just one piece of 18mm routed to look like four drawers. Its a bit fake looking if you study it but the overall effect is good. It was all getting a little too stripy looking so the fake drawers brake it up a bit...

[big-all]

Yes the drawers under the hob were an afterthought, as the oven was originally supposed to go there. Its just one piece of 18mm routed to look like four drawers. Its a bit fake looking if you study

go for a shadow very very slightly darker colour in the groove to give it depth and sepertation

[slennon]

Oh thats an idea. A slight shadow... Thanks