Re: more about router bits

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: : The problems you describe can be dealt with by having the right feeds and speeds. If you are generating enough heat to turn your bits blue or burning the MDF to the point that the glue turns to carbon, something isn't right. Also, if you notice any kind of buildup on your bits, soaking them in a solvent overnight will clean them to prevent premature burning and dulling. I wouldn't try this with carbide tipped bits though, as I understand that the carbide is bonded to the steel and the solvent could affect the strength of the bond. I have been using High speed steel bits on MDF routinely with my 4'x8' CNC router table, and haven't experienced this problem yet. I also tend to favor 4 fluted mill bits designed for cutting through steel, and it goes through MDF like butter. Granted, I have only put about 200 linear feet on my current bit, but it hasn't had the problems you describe. Of course feed rate cannot be controlled very well with a handheld router, so this should be considered as well. : Another thing people should be aware of is that solid carbide is brittle and when pushed beyond it's limits will actually shatter (which I am sure you are already aware of). There is someting unnerving about the prospects of shards of metal flying off of a spindle at 20,000 rpm :). : I'm not disputing what you say, I am only stating that there seem to be two schools of thought on this issue (also from individuals who have spent 20+ years making their livings at this kind of work), and the incredible variation of bits, materials, machinery and processes (feeds and speeds, desired finish quality, etc.) doesn't make it any easier to come to a definitive solution. The general consensus from the woodworking folks I have talked to seems to be to try different things until you are happy with the results and stick with what works the best in your situation. : Just some more observations :) : RandyT : : Randy, Trust me the high speed steel bits won't cut it, your premium carbide bits will last, not as long as we like sometimes but we use this stuff in case works daily, and I have heaps of bits, the problem is not the wood its the fact the glue used in particle board and MDF turns to carbon when subject to heat (aka router speed) We had a tool maker come to our shop on this problem, slow the router speed down, speed up the feed rate and the carbide is the only thing that is comercially available that will work (short of diamond tooling, we checked into this also not feasible about 100 bucks per bit) the carbon formed is virtually as hard as the carbide and dulls it quickly. A carbide router bit should just pick at your fingernail when sharp, very true that it cannot be sharpened to an edge like steel, it just lasts, the steel will burn up, turn blue and loose its temper, and then is no good, it can be sharpened but will no longer hold a edge, a good quality carbide bit only needs resharpening. I am not trying to be a no it all on the subject,its just we use this stuff daily to make our living, I have co-owned a shop the past 15 years and produced many pieces of casework & cabinetry, on the production & custom levels, fortunatly making my living doing so. Best of luck Matt : : : : MDF is great stuff... smooth, easy to work with, easy to finish, sturdy. Only caveat: it eats router bits for lunch. Geez. There's something demoralizing about staring at a worthless piece of scrap metal that five minutes previous had been a $10 router bit. : : : Just a quick note about bits, solid carbide is very durable, but won't have as sharp an edge as a high-speed steel bit. However, it will keep that mostly sharp edge for a longer period of time. : : : A friend of mine who has been in woodworking for about 20 years says that you are better off buying 3 or 4 high speed steel bits (at about $4 each and which can be re-sharpened) than a more expensive solid carbide bit (about $15) which dosn't perform as well, but lasts longer. : : : Not sure how this applies to your situation, but I thought I would pass on the info. : : : RandyT

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