Forstner sharpening

[pshrynk]

So I was turning a pair of salt/pepper grinders using marble wood and Yucatan rosewood. It called for a 1 inch Forstner hole. Very soon after starting the rosewood, the thing started smoking due to bit friction, etc. I was using water with Dawn to cool it off every half centimeter or so, but it didn't help much. Worse with the marble wood. I tried to file the cutting edges, but the stank just kept coming and my house smells of burnt wood now. So, is there a way to sharpen Forstner bits other than "new Forstner bit"?

 

[Woodchipper]

Watching.

 

[Swagopenturner]

Try this site: https://www.woodmagazine.com/woodwo.../drilling-boring/how-to-sharpen-forstner-bits
There are also lots of YouTube videos showing you how to do it.
Much cheaper than replacing them!

 

[pianomanpj]

http://www.leevalley.com/en/html/06j0104ie.pdf

 

[WriteON]

http://www.leevalley.com/en/html/06j0104ie.pdf

Interesting. I tend to go against every rule but that's how we learn. Too fast will kill/dull. Won't stay sharp long once it is overheated.

 

[monophoto]

So, is there a way to sharpen Forstner bits other than "new Forstner bit"?

Yes - and it's quite simple. Use a diamond honing paddle to polish the flat face of the cutting edges (the two edge that extends radially out from the center of the bit) Remember that a cutting 'edge' is where two surfaces come together, and in the case of a forstner bit, polishing the large face renews the edge.

There are a few YouTube videos out there that suggest using a dremel with a grinding stone to polish the inside of the round portion of the bit. In my experience, that usually isn't necessary. Most of the work is done by the radial cutting edges.

It's quite amazing how much improvement there is from a few strokes of a diamond paddle on those cutting edges.

 

[pshrynk]

Obviously did it wrong. Spousal Unit MkIII is still complaining of the smell... Just flat against the surface, then?

 

[monophoto]

Yup. A little lapping fluid helps, but if you don't have any, water or spit will also work.

 

[John Eldeen]

As a person who has made hundreds of peppermills and saltmills I fell or pain drilling that long hole into end grain is rough. To your question yes you can sharpen a forester bit there is plenty here who love there diamond paddles but in my opinion for this task a polished edge is not necessary. I use a fine cut file it gets it sharp fast a seams at lest for me to last longer as I have tried both ways. Next is what to actually sharpen this is not the best description but please bear with me. Any cutting face the is "parallel" with the work peace should never be sharpened. The main cuting face running "parallel" with the shank is what you want to sharpen. You also want to try and sharpen both of the faces about the same amount. Last thing is a tip that works for me. Holding the bit is kind of a pain so try turning our tailstock backwards on your lathe at the end of the bedways then intall you bit into the tailstock. Now you can change the position of the bit radially until the faces are in a comfortable position to work.
Just for my own curiosity what kit are you using are of the kits I have used the main drill is a 1 1/16 hole?

 

[jttheclockman]

The term forstner bit gets thrown around alot and used incorrectly. My question is are you using a true forstner bit which is not the bit to be drilling end grain. There are Knife edge, Wavy edge, saw tooth or multispur, or carbide. Yes you can sharpen them but take some practice and others have linked sites so I won't bother. I will say 3 things, saw tooth, pay strict attention to speed for the size bit, and sharpness and cleanliness. Drilling resin woods such as rosewood will build up resin on cutter edges so need to keep clean.

 

[John Eldeen]

The term forstner bit gets thrown around alot and used incorrectly. My question is are you using a true forstner bit which is not the bit to be drilling end grain. There are Knife edge, Wavy edge, saw tooth or multispur, or carbide. Yes you can sharpen them but take some practice and others have linked sites so I won't bother. I will say 3 things, saw tooth, pay strict attention to speed for the size bit, and sharpness and cleanliness. Drilling resin woods such as rosewood will build up resin on cutter edges so need to keep clean.

Ok John I will bite what style for drill would you recommend for drilling a 1 1/16 hole into end grain. I only ask because a forester bit is the only drill I have ever seen recommend for this particular task.

 

[pshrynk]

Um... it's called a Forstner bit on the package. The edge looks a bit like a saw blade. The kit is the Pump-N-Grind that I god from Woodcraft. I tried running at the slowest speed, but the motor just kept getting hung up. Probably a function of the dullness of the blade, I suppose?

 

[leehljp]

1. I have had 1 set of the 16 bit Harbor Freight bits, one of Grizzly, gave one away to a son in law, and then bought a set of Freud Forstner bits. The Freud bits are head and shoulders above the others. A "Very Good" set is more expensive but sure cuts better.

2. Other than sharpening what you already have, my technique is this: use the correct size forester (your 1 inch) and drill about 3/8 inch into the end grain blank. Switch bits to 1/2" or use a 1/2" regular drill bit (sharp) and drill with it to the depth needed. By doing this, you lessen the pressure needed and the pressure on the 1" forester bit itself, and it will not heat up as fast since it is cutting 1/3 less wood. The original 3/8" deep cut by the 1 inch will get your forstner bit lined up to finish drilling. I have done that several times.

 

[SteveG]

I have used the same technique as mentioned by leehljp, and it works well. As indicated, starting the hole with the final size Forstner is critical to the process. This is basically a variation on step drilling to avoid the heat and possible tear-out from jumping in with a large bit.

 

[jttheclockman]

Ok John I will bite what style for drill would you recommend for drilling a 1 1/16 hole into end grain. I only ask because a forester bit is the only drill I have ever seen recommend for this particular task.

I mentioned I recommended a saw tooth type forstner bit. Then again it depends on what you are drilling for and how deep and is a holesaw not acceptable.

Types of forstner bits

There are two types of forstner bits – those with a continuous rim and those with a saw-tooth rim. Continuous rim (as shown) bits leave a very clean edge and are best for smaller holes, while saw-tooth bits produce relatively rough holes, but are better for larger holes (over 25mm in diameter) and last longer.

The continuous rim come in straight and wavy as I mentioned. The straight was the very first forstner bits Those are great if you have a need for clean sides and not so deep drilling because they dull faster than the saw tooth because they heat much faster from the metal constantly making contact. Saw tooth will be easier for longer depth if you keep sharp and clean.

Just read Hanks method and this will extend the life of a forstner bit too. Carbide is another option. I use carbide when drilling my billiardball clocks.

 

[John Eldeen]

I mentioned I recommended a saw tooth type forstner bit. Then again it depends on what you are drilling for and how deep and is a holesaw not acceptable.

Types of forstner bits

There are two types of forstner bits – those with a continuous rim and those with a saw-tooth rim. Continuous rim (as shown) bits leave a very clean edge and are best for smaller holes, while saw-tooth bits produce relatively rough holes, but are better for larger holes (over 25mm in diameter) and last longer.

The continuous rim come in straight and wavy as I mentioned. The straight was the very first forstner bits Those are great if you have a need for clean sides and not so deep drilling because they dull faster than the saw tooth because they heat much faster from the metal constantly making contact. Saw tooth will be easier for longer depth if you keep sharp and clean.

Just read Hanks method and this will extend the life of a forstner bit too. Carbide is another option. I use carbide when drilling my billiardball clocks.

Ok understand I thought you were saying that a forester bit was the wrong type for end grain at all for peppermills I use a colt maxicut and drill upwards of 8 inches deep regularly with good results. I have to touch up the edge about every 5 mills or so but I am working with some really hard wood most of the time.

 

[jttheclockman]

Ok understand I thought you were saying that a forester bit was the wrong type for end grain at all for peppermills I use a colt maxicut and drill upwards of 8 inches deep regularly with good results. I have to touch up the edge about every 5 mills or so but I am working with some really hard wood most of the time.

I love those Colt bits too. Use them alot.

 

[pshrynk]

When all was said and done and SUMkIII had exited the room, I wondered if a pilot hole would have been a good idea. I can certainly sharpen the regular bits with the Drill Dr much easier. Thanks!