sanding mdf

[Pip]

After routering mdf I always get a "furry" finish, usually I apply some primer to stiffen the "fur" then sand it smooth(ish). is there an easier or quicker way to get rid of it?.
All ideas welcome,
Thanks,
Pip

 

[Midnight]

Pip...

I canna comment specifically for MDF... never used the stuff... but with ply, ragged or furry edges are a sign that the cutter's getting tired and could use a wee tickle on a stone. I'm guessing that the nature of the stuff MDF is made from makes it more inclined towards furring, requiring sharpening the cutters a lot sooner than ply or solid stock.

 

[thomaskennedy]

Like Mike i dont really use MDF that much but maybe you could try plunging the cutter down a fraction to take off the tinyist bit, which should be the "Cleaning cut" but make sure its only like half a millimeter cos it won't work otherwise!

Hope this helps

Ta

Tom

 

[Anonymous]

pip i had the same problem with the only thing i made from mdf a fishtank stand, boy dont get mdf wet .Anyway i tried several cutters and resharpened a few but had no joy so i resorted to a profile sander .I did get a slightly better finish with convex cuts rather than concave .no idea if its something to do with the makeup of the material .

 

[Bean]

The only method I am sure of is to use wall paper paste on the cut edge and when dry to sand back as normal.
Its much like your primer method, except that I think that the paste will penetrate further into the edge of the MDF.

Bean

 

[Newbie_Neil]

Hi Pip

Assuming that you've got good sharp cutters and it's still happening why not try this. I've not tried it with mdf, but it works in soft and hard wood.

I've assumed that you are using a fence or guide. When you have made your final pass, don't change anything and just do the cut in reverse. It is particularly useful if you have any burn marks (not that I ever suffer from them, of course :wink: ). If it can clean up burn marks it should work with furring on mdf.

Please let us know how you get on.

Cheers
Neil

 

[Aragorn]

When you have made your final pass, don't change anything and just do the cut in reverse.

Are you talking about doing a climb cut here N_N? If so <granny/eggs> be aware that the router wants to pull you in the direction of the cut, so hang on!
As to MDF, Pip, I think this is the nature of the material. It isn't really comparable to wood. "End grain" is always pretty fluffy (cf wood) and any cuts into the smooth surface (like housings) will always reveal the crud that it's made from.
It can be sanded to a reasonably smooth finish as you've found, but it won't finish that way straight from the cutters.
If I use MDF, I always cover the edges with wood, using the MDF purely for it's smooth surface. Horrible stuff :?

 

[Jaco]

I have found it to be caused by "blunt" bits.

 

[Anonymous]

I think that MDF is very abrasive and thus you might find the cutter has blunted very quickly.
I would say that a rough cut down to, say 0.5mm from finished size, followed by a small final cut might do it. Also rub a small diamond stone along the cutter to sharpen it.

 

[Newbie_Neil]

Hi Aragorn

Are you talking about doing a climb cut here N_N? If so <granny/eggs> be aware that the router wants to pull you in the direction of the cut, so hang on!

It's as recommended by Ron Fox for getting rid of burn marks, particularly on softwood.

If you are doing exactly the same cut, but in reverse, it shouldn't really do anything but it does in fact successfully remove burn marks. The important thing to remember is that you don't move the fence, cutter depth etc. etc. Nothing changes, except the direction of cut.

Of course, this is not something I have ever needed to use myself. :wink:

Cheers
Neil

 

[Pip]

Hi guys!,
Thanks for the help, although I had finished the job, I tried the back routing on a spare lump but it didn't make a great deal of difference,I also tried it with a brand new cutter, this also didn't do much,the one thing I didn't try is the wallpaper paste as I think it will be just like the primer. the back routing (climb routing?) does get rid of burns on wood,I've used it a few times before,but care is needed with the digits. the one thing I use to get a reasonable finish is a little spongey thing called a "Sand Blaster" from 3m, it follows the contours quite well.
I'll try not to use mdf in future, I prefer looking at a nice piece of grain anyway.
Thanks again,
pip

 

[Chris Knight]

Gill,

Pop your head above the parapet - you were an expert on this IIRC.

 

[Midnight]

I'll try not to use mdf in future, I prefer looking at a nice piece of grain anyway.

the lad's showin potential.... never a bad thing.

 

[Pip]

I'll try not to use mdf in future, I prefer looking at a nice piece of grain anyway.

the lad's showin potential.... never a bad thing.

don't worry, I'll cover it up if any ladies come.
pip