I am trying to make MDF shaker cabinets doors. For right now I’m just using a 1/4, 2 flute downcut bit. I plan to buy the 4 bit shaker door set soon.
The panel comes out extremely furry and no amount of sanding helps.
Can anyone tell me how to get a smooth surface?
Hit it with a primer or glue water then sand
In general MDF can be difficult to get smooth but there are ways. One of them is to spray a layer of sanding primer. This will allow your grain to break off rather than getting bent down when sanding. Multiple coats may be required. You can also try a Shellac if you don’t plan to paint it for whatever reason but it would also work if painting.
Whichever method you intend to use, the point is to snap this fuzzies off rather than pushing them flat which is what traditional sanding is accomplishing and why you can get it smooth.
Make sure you are using a good quality MDF. Some of the stuff at the home centres is pretty poor quality. Phone around, see if you can find some cabinet shop quality MDF. Not much more expensive, makes a big difference. I use Ranger Board or Plum Creek
An HDF is better, specifically for doors and drawer fronts. Start there and you will notice an immediate difference.
Try swapping out the downcut bit for a compression bit. I’ve had great success with it. Alternatively, try an up cut bit. A down cut is pushing the cuttings down, possibly fraying the face of material more than usual.
Decrease your step over after you’ve tried different bits.
This is presuming your following the manufacturer feeds and speeds for the bit.