MDF knobs

[Chuck Pickering]

Making some mdf knobs(first attempt) for my nearly finished router fence. I'm using a trick seen on here and Youtube. Drew some layout lines on a scrap of mdf and used a Forstner bit to create the grip ridges, then cut out the profile with a 2" hole saw. I'm using nut plates with the spurs for thread inserts. My issue is, when using the Forstner bit, I had to shut off the drill press and clean the waste out of the Forstner bit often, as the waste would slow the cutting and smoke a bit. A real PITA!
Is this just normal? Is the mdf damp(doesn't seem so)? Wrong feed/speed? Do I need to do something to the (cheap HF, but I'm happy with them so far) Forstner bit?
I'm using a scrap of mdf as a backer for drilling. The break out of the forstner bit holes was still quite rough, but cleaned up on the disk sander nicely.
Forgive my ignorance, haven't done much with mdf.

Chuck

[keith wootton]

why not use real wood. i think most hardwoods would stand up to being a knob better than mdf.

[Chuck Pickering]

Well, I managed to make a couple knobs from the mdf. Sanded/rounded the sticky out bits on the disk sander and rounded the edges with 1/4" round over bit. Sanding cleaned up the breakout. Imbedded a toothed nut plate. Table clamps for the router table fence done! I will definitely play around with other materials and make some more.
I think with the next batch, when I lay out the knob and finger pattern, I'll drill through with a tiny drill bit to mark the pattern so I can drill with the forstner bit from both sides without risking break through .

Chuck

[Mike Gresham]

Forstner bits do not clear the chips well. That is based on personal experience and just about every bit comparison I have read. However, if you need a flat bottom hole they are the way to go. I would use a brad point bit for a through hole.

[Steve Demuth]

You should be able to zip right through mdf with a Forstner bit, with very adequate chip clearance. But in both mdf and masonite, with a Forstner bit, you'll likely have to stop the drill press after each hole and clear a round out of the bottom of the bit before the next hole. The side cutters on Forstner bits cut a perfect little pancake that stays in the bit when you lift it, and yes, if you don't remove it, the bit will have a hard, hot time in the next hole.

But why make knobs out of mdf? Not very substantial stuff for that sort of thing.

[Bruce Wrenn]

You must be into torture. With commercial knobs only costing a couple bucks or less each, I can't justify making them.

[Rich Riddle]

This doesn't meet the time/benefit consideration, but to each his own. It seems like one of those adventures where it's possible but not practical considering the limitations of MDF. Some people have more time and others value time. With the same amount of labor requirements for hard wood. that would be the way many would go.
You must be into torture. With commercial knobs only costing a couple bucks or less each, I can't justify making them.

[Mike Heidrick]

When the fostner bit spur breaks though flip the mdf over. Sounds like your rpms are too high and you are melting the resin in the MDF. That or your forstner is dull. Try a freud forstner or cmt. Adjust speed too. Mdf is hard on a forstner bit. I prefer spiral router bits in a router for mdf. Dust collection is a good idea too.