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all they are doing is squaring up the cutting face so its nice and crisp, so i'd say very very little metal is removed. as usual i am chiming in without really knowing what i'm talking about, but i am pretty experienced with chisels and gouges and scrapers. i'd give it a shot myself before sending them out unless they are so far gone they need grinding; think i'll try this weekend after looking at this short article: http://www.highlandwoodworking.com/care ... rbits.aspx

Hi Filippo,

The Forrest blade company of Clifton NJ sharpens router bits as well as saw blades.

I have dealt with them and used their blades and sharpening services for over thirty years .

They are the best!

Their website explains the process they use.

Brad

Hey Filippo,

It's been quite a while since I've dealt with the sharpening services that we used at the cabinet shop. I do remember getting undersized bearings for the 1/2" flush cutting bits. They are .490" diameter and are still available according to my supplier's website. Don't recall how many sharpenings it took to lose the.010". Sorry I can't be any more help than that.

Mark

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+1, send mine out to them. Router bits can usually be sharpened 2-3 times before they need replaced.

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Brian

You never know what you are capable of until you actually try.

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Its all relative Filippo...if the user does a regular touch up with a diamond plate and then send the bit in for a grind before allowing things to get too bad, then minimal material should need to be removed to get the bit up to scratch. If on the other hand a user feels that they need to keep pushing the cutter to get the most value from it and end up leaving it too long to a point of abuse, then the saw doctor will not have any option but to grind heavy and loose some of the profile to get the bit sharp again...The set of the carbide has a big impact as well, don't expect much from cheap bits, they are low cost for good reason...finally, with so many cheap bits on the market, there is potential at every saw doctor for an inexperienced employee to assume all bits are created equal and proceed to grind your pride and joy into S_H_I_T..

Cheers

Kim

OK, I've got a 7/16" bit that I had resharpened. It didn't have any chunks missing so they were able to remove the minimal amount of material.

It went from 0.4375" to 0.4347" (approximately as measured by a dial caliper).

Just looking at the bit & trying to gauge how much material was removed, I'd guess it could be resharpened 2 more times for a total of 3.

Kevin Looker

edit:
Also keep in mind that to take away the minimal amount, they will have to change the geometry of the cutting edge slightly which can affect performance.

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
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As a machinist I have resharpened many tools. The variable is how much that has to be removed to get to a good edge. I would start at .010. Sometimes you need to rejoin the the cutting surface so the cutter flutes are working on the same plane. The best case scenario is .010 in. Worse case is what it is .
Also who does the work determines how good it will be. I also think Forrest does excellent work. Often it will cost more to sharpen a router bit that it is to replace . Just food for thought .

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John Hall
blues creek guitars
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You Don't know what you don't know until you know it

Depending on how you use the bit, I used to get my spirals sharpened tip only, that is where it got dull and burned, then I was able to keep the .5 dimension. It took many sharpenings before some of them became too short. The one spiral that was edge sharpened lost about .010, and has not been used much as a result. The straights with bearings would return with matching bearings, I never did any of these more then once, but that was just how it worked out, not because the shop imposed any limitations. I assumed they would grind these to match the undersized bearings they had.

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That is not surprising to me. Many of the saw sharpening services that sharpen tools for cabinet shops also sell blades and bits. The fewer sharpenings possible the more product they sell. Shops often buy from them for convenience, not so much for price. Usually they grind them pretty hard. One to two sharpenings and they are done.
I worked in one shop that would toss the used straights rather than having them sharpened. The sharpened bits didn't stay that way as long as new bits so the cost was about the same.
I like to touch them up with a diamond hone and avoid sending them out as much as possible.
If you bought "sharpened" bits, you may have bought bits that were sharpened but have no more sharpenings left. Usually the carbide is thin and they don't hold an edge too long. Good for occasional use by "Joe Homeowner".

That's why I started sending all my stuff to Forrest for sharpening. I get the same life from what they sharpen as I do from new. No local shop can do this in my area, they all only last about 1/2 as long at best as they did when new. I assume it is the quality of equipment that a manufacturer like Forrest has verses a local sharp shop.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/