# Bit wear



## pusserboy (Mar 4, 2018)

I've seen somewhere that using MDF will dull a bit faster than wood. If so how hard is MDF on the bits and should it be avoided.
Thanks
Stuart


----------



## Stick486 (Jan 4, 2013)

pusserboy said:


> I've seen somewhere that using MDF will dull a bit faster than wood. If so how hard is MDF on the bits and should it be avoided.
> Thanks
> Stuart


it's not the hardness it's the abrasiveness...
IIRC there is about a 30 ~ 40% reduction in bit life...
economy bits don't last because of the softer carbide...
the dust is major detrimental to your health...

MDF is basically glorified particle board.
Just like particle board, MDF will soak up water and other liquids like a sponge and swell unless it’s very well sealed on all sides and edges with primer, paint, or another sealing product. 
Because it consists of such fine particles, MDF doesn’t hold screws very well, and it’s very easy to strip the screw holes.
Because it’s so dense, MDF is very heavy. This can make it more difficult to work with, especially if you don’t have a helper who can help you lift and cut the large sheets.
MDF can’t be stained. Not only does it soak up stain like a sponge, but also because there’s no wood grain on MDF, it looks awful when it’s stained. (Kind of like staining particle board. Why would you bother?)
MDF contains VOCs (urea-formaldehyde). Off gassing can be greatly minimized (but probably not eliminated) if the MDF is encapsulated with primer, paint, etc., but care needs to be taken while cutting and sanding to avoid inhalation of the particles.


----------



## JOAT (Apr 9, 2010)

Can't tell you on that. I hate MDF, and don't use it. So, it doesn't wear my bits any at all.
:grin:

But, bits will wear out, no matter what you use them on. Me, I just buy another bit when one wears out, and don't worry about it.


----------



## Steven Owen (Aug 14, 2017)

JOAT said:


> Can't tell you on that. I hate MDF, and don't use it. So, it doesn't wear my bits any at all.
> :grin:
> 
> But, bits will wear out, no matter what you use them on. Me, I just buy another bit when one wears out, and don't worry about it.


I would think you could get 5-6 sharpenings out of a high quality bit. I’m surprised you’d be tossing any dull bits out.


----------



## Herb Stoops (Aug 28, 2012)

Talk about dull bits, the original router HSS bits didn't last long, When they turned from blue to black they were over done , just toss them, when they cooled off.
Herb


----------



## JOAT (Apr 9, 2010)

Steven Owen said:


> I would think you could get 5-6 sharpenings out of a high quality bit. I’m surprised you’d be tossing any dull bits out.


Possibly so, but there would be no money advantage to me by sharpening, I actually come out a bit ahead by buying new. Highly possible that this is so because I just use flush trim bits for about 99.99% of what I make. If I used different types of bits, this might not be so. Then there is the fact that I don't buy high quality bits, just decent quality carbide bits, at decent prices. Not sure how long I've been using my present bit, but it's been several years.


----------



## DesertRatTom (Jul 3, 2012)

I have a couple of small diamond sharpening cards that are for sharpening bits. The trick of sharpening is to make the cutter edge as square as possible. You don't sharpen the outside edge, that can alter the width and profile. You sharpen the flat, really its almost polishing, you're just reestablishing that edge, not grinding one. Note the Trend lubricant.


----------



## pusserboy (Mar 4, 2018)

Thank you all gentlemen. Will take your advice.
Stuart


----------

