MDF Shaker doors

[Bluewater]

I'm planning to make shaker kitchen doors and drawer fronts from MR MDF. Rails and stiles 120 X 22mm and panels 9mm. I hope to get the 22mm cut by the mdf supplier say 2mm oversizes so that I can finish the edges with a router. I would also like to slightly round the outside edges of the stiles and rails both sides. I thought I could get a router bit that would finish the edge and make the slight round at the same time but spoke to Trend and there's no such thing. Their smallest round over bit is 1.6mm radius which is much too big. So my question is how to I achieve this slight rounded edge? I also plan to do the same to the left and right front ends of the rails to achieve a groove when they are joined to the stile. I've got some shaker style mirror frames at home (oak) and the groove looks chamfered but the inside and outside edges are more rounded. Maybe a chamfer followed by a light sanding is the answer. Never done this before so would be very grateful for advice from those with experience.

 

[Oryxdesign]

If I understand correctly you propose to make a template from say 6mm mdf the correct final size for the door, then copy route the oversize doors to that template. That sounds fine.

Use something like
http://www.wealdentool.com/acatalog/Onl ... m_279.html

For the rounding over 1.6mm is quite small if you want a smaller arris just finish with sandpaper on a soft pad.

Is this what you mean for making the joint?
http://www.wealdentool.com/cgi-bin/sh00 ... 44_2d1_2f2

Of course some might say that all this is a bit unnecesary in mdf and you could achieve the same thing, stronger by laminatinating 6mm 9mm and 6mm to give 21mm overall.

 

[petermillard]

MDF cut on a panel saw or circular saw should have a perfectly good edge, so provided your supplier can cut to size accurately, you'll just be making work for yourself finishing the edges off with a router, IHMO.

To get a slight groove where the rail and stiles meet I usually just put a slight bevel on them with a v-groove router bit - set the fence/depth with a bit of trial and error on a scrap piece first. Never come across one that's slightly rounded-over as well, but if it's as fine as you suggest then a quick pass with a sanding pad should do the trick.

Oh, and welcome, btw

HTH, Pete

 

[Bluewater]

Thanks very much Simon and Pete for your helpful replies and the links. Since writing the post I have read another recent post recommending Wrights Carpentry. Their precision suggests you are right that finishing the edges with a router is unnecessary which would be great. From what you say I think I've been making too much of the rounded edge issue.

I've read on the forum about making the doors by gluing strips to a panel to resemble conventional construction and like the idea. Instead of 6mm either side of a 9mm panel wouldn't 12mm onto one side of a 9mm panel be better because it would be flush inside?

Thanks again

Peter

 

[Oryxdesign]

You run the risk that it might warp, it probably wouldn't but it is good practise to do both sides.

 

[jasonB]

You do have to watch out for warping if you only glue to one side. Also it will be hard to get teh two or three strips flush when gluing up so in that case they will want trimming once glued.

As the others have said straight off a good saw will be fine with a light sand. I'm not keen on the chamfered/rounded edges, always strikes me of mass produced items where the camfer hides small discrepancies. If you do want it then a bearing guided chamfer bit works well and 1.6mm (1/16") radius is a lot smaller than you see on a lot of doors done this way.

How are you going to takle the corner joints? I tend to run the panel groove onto the ends of the rails as well and then use a strip of the panel material as a loose tongue which is quick and strong, like this

J

 

[Bluewater]

OK understand about possible warping. For the joints I planned to extend the groove as you say but make tenons on the rails. But your loose tenons or biscuits look easier.

I wanted rounded edges because I thought they would take the paint better but maybe not so rounded as to require machining.

 

[George_N]

Jason's loose tenon method is much better than trying to machine tenons in MDF. Even the MR stuff is quite "fluffy in the core. I've used it successfully with standard MDF for kitchen cabinet doors and big drawer fronts...no warping and so far very durable.

 

[Oryxdesign]

I wanted rounded edges because I thought they would take the paint better but maybe not so rounded as to require machining.

This is true and worth doing, I agree it needs to be the smallest round over you can do. Personally I think 1.6mm is fine and you don't need to use the whole of the round over.

The loose tenon method is a good one. If you don't have enough clamps to do the whole lot in one go you can clamp together and fire a couple of pins through the tenon, unclamp and get on with the next one.

 

[jasonB]

I wanted rounded edges because I thought they would take the paint better but maybe not so rounded as to require machining.

In that case just a swipe or two with a blockplane and a light sanding will do. For the edges around the panels sand the flat edges before glueup and afterwards just use a block and sandpaper to knock the corner off, none of it needs routing.

If you are cutting the panel grooves with a router its better to use a grooving bit and keep the face side against the table than a straight bit with the work on edge. I use a wobble saw in teh spindle moulder

J

 

[Lord Kitchener]

I agree that the loose tenon is the easiest way, but you need to have a think about how you are going to cut the slots in the ends of the rails, you really need a router table or a spindle moulder with a sliding table for that job, the issue being to hold the rail at right angles to the cutter, and the cutter will need to be dead parallel to the face of the stock. Reading between the lines of your posts, I am wondering if you wouldn't get a better result gluing stips onto a full size panel as suggested earleir rather than making frame and panel doors.

 

[Bluewater]

Thank you everyone for great advice. Really helpful.

Peter

 

[Oryxdesign]

Yes easiest on an RT but possible without. You don't need a sliding fence you just need a square offcut of mdf, it only needs to be square to the fence and the fence doesn't need to be square to anything else. It's nice to have a handle on the square off-cut and safer. Always work from one datum side then there isn't any alignment issues.

As LK says if you aren't comfortable with this go for the strip method, cleaning up can be done with a plane.

 

[jasonB]

Yes I just use an offcut of MDF to keep the rails square to the fence even though I have got a sliding table.

If you don't have a table then a slotter with bearing will be easy to run round the side & ends. It just takes a lot longer than shoving them over a table as you have to hold down each board. You can also collect the dust easier on a table or spindle.

J

 

[xy mosian]

I'm interested in the laminated door technique for possible future use. However I have read that moisture reistant mdf allows a better paint finish. Can MR MDF be succesfully glued with pva adhesives, or is it necessary to use a different adhesive?
xy

 

[Oryxdesign]

PVA is fine

 

[xy mosian]

Thanks Simon
xy

 

[custard]

However I have read that moisture reistant mdf allows a better paint finish.

I've only painted MDF a few times so I'll defer to those with more experience. I also found MR MDF took paint better on the edges than normal MDF, but it wasn't that much better. Maybe I'm being too picky, but I haven't found any MDF where painted edges don't "fur up" to some extent without quite a bit of additional treatment and preparation.

 

[Lord Kitchener]

However I have read that moisture reistant mdf allows a better paint finish.

I've only painted MDF a few times so I'll defer to those with more experience. I also found MR MDF took paint better on the edges than normal MDF, but it wasn't that much better. Maybe I'm being too picky, but I haven't found any MDF where painted edges don't "fur up" to some extent without quite a bit of additional treatment and preparation.

We just use several coats of paint, eventually the edges smooth out. Our doors get painted (brush) flat, three coats each side, so the edges get six. Water based paint (Dulux)dries quickly and gives good covering.

 

[xy mosian]

Another useful very useful tip. Thanks m'lud
xy