Thread: Understanding forstner bits

Baladonia are HSS, they are touched up using a diamond file
TC (means tungsten carbide - thats where the expense is) won't ever need sharpening. Really only necessary if many many many holes.

I've had my set of cheap HSS Forstners for about 15 years - I use them mainly to drill holes in Al. Still cutting fine.

As bob said HSS Forsteners are fine and you can sharpen them. Mine were the generic carbatec set. I use them a lot for endgrain work on the lathe but very handy in lots of woodworking. Had mine about the same time and only the most used ones have needed a sharpen. Be warned that anything over 1'' can be a handful in a hand held drill.
Regards
John

When using Forster bits use a slow to moderate speed and a high feed depending on the size.
Never use a high speed and light feed, you’ll burn them.
Best to clamp the job down on a drill press, you can overlap holes to hog out waste.
H.

On smaller cutters Round shaft drive doesn’t matter but as they get larger in diameter hex drive bits are way better. But you can expect to pay heaps for them.

And really they are not easy to find hex drive bits. Some are two flute some are three flute and some are saw tooth bits. Depending on the type of timber you are cutting basic Forstner are fine. If you have a choice saw tooth, three flutes with hex drive is number one but you would expect to pay heaps for them.

Forstner bits and matching plug cutters are so so much cheaper now for decent quality. I have many sizes and always a matching plug cutter up to 25mm in diameter. With HSS bits don’t be frightened to sharpen them but never touch the OD of the bit. But as it has been mentioned before a small diamond file on the internal flutes can make a huge different.


Steven

Set of 5 carbide tipped with hex shank for $70 at Carbitool 5 Piece Kit (TCT Metric) - Carbitool
They also have a full range in HSS

I used a set of forstner bits from Carbatec for about 20 years. I really do not know how they lasted that long .. I guess that I did not know any better.

In hindsight, they could still be going strong today (some are) if I had know a few things: most importantly, they do not like high speed. You need to determine what is optimum for each type and size of forstner bit. Many of the one I tossed were a result of burnt steel (which as meant burnt wood) as the drill press was set for one speed for all. (Now I have a Nova Voyager, which will dial in the preferred speed ... but not all are as lucky. I did, however, learn my lesson before this purchase).

The second factor is to learn how to sharpen these little buggers. Dull cutters will not only create poor holes, but they create heat and this dulls the cutters more and burns the wood! Second

The reason why some of the Carbatec bits survive is that I learned to sharpen them before they burned. There are a number of decent videos on YouTube to guide you. Not hard at all ... in many ways, it is the same as sharpening hand saw, which I think is also a required skill for anyone using hand saws. They are not disposable, and you do not throw them away when dull ... does one do that with twist drill bits?

Check out the different types of forstners. Recognise that Carbatec, and all the other stores in Oz, sell Chinese cheapies. Maximum profit and poorer steel, and the latter will have you sharpening more frequently. If all you plan to do is the occasional bit of drilling, then they are fine. I have a cheap set from a wood show that looked fancy in a fancy box that looked a bargain, but would not cut to save your life. I sharpened them, and they are just fine for non-show work. My best forstner bits are very hard HSS - I cannot sharpen carbide.

There are a number of excellent forstner bits available: Lee Valley sell an excellent set (I suspect made by Colt). There are Framag, and Fisch. I have chosen to go with Colt, which have a superb reputation for durability, clean cutting and chip ejection. Look after them, and they are a lifetime tool.

Regards from Perth

Derek

Just a note on "burning up" bits; if that happened they were probably just carbon steel, not HSS.

HSS was specifically invented to stay hard when red hot (up to about 600 degrees) and any burning or bluing is cosmetic only. They can still be resharpened as normal and will retain all the hardness they had from the factory.

Originally Posted by elanjacobs

Just a note on "burning up" bits; if that happened they were probably just carbon steel, not HSS.

HSS was specifically invented to stay hard when red hot (up to about 600 degrees) and any burning or bluing is cosmetic only. They can still be resharpened as normal and will retain all the hardness they had from the factory.

Which indicates that the forstners I have from Carbatec are not HSS or are poor quality HSS.

Regards from Perth

Derek

The Carbatec brand bits are just tool steel, they say so on the website.

Originally Posted by SuperM

I see two kinds of forstner bits in Timbecon and a vast price difference. Why? I have read TCT are much more expensive but why is baladonia so cheap? What is it made of?

https://www.timbecon.com.au/baladoni...-sawtooth-bits

https://www.timbecon.com.au/torquata...ing-drill-bits

Hi SM

If you check Timbecons videos they have one where their demonstrator (Patrick Holcombe I think) advises against sawtooth because of their tendency to burn and smoke.

cheers
Keith

Have a cheap nasty set of these from the glorious peoples republic of crap. Aldi by the way but sold in many places. have gone blunt very quick. Have wondered about how to re sharpen or if it's even worth it. Can't speak for the carbide version -Should last longer -but also probably Chinese -Much like the saw blades. It's a case of what they cost -how much is a re sharpen or throw them out.

I've got the Torquata TCT forstner bits in a few sizes and they are excellent. They leave smooth clean walls and cut pretty effortlessly. I'm only a home woodworker so I can't speak for their durability in a heavy use environment but I've used one particular 38mm bit for many holes in white oak and spotted gum and (more than a year later) it still cuts like new. Added bonus is you can be lazy and leave your drill press on a fast speed with no ill effect to the bit.

I have used one 19mm of these without having any issues with it Geman brand FAMAG Bormax 2.0 Forstner Bits Series 1622 | FINE TOOLS

I bought a cheap set of 5 off eBay about 8 years ago. I had little experience, used high speed and they burnt as I drilled into 80yr old recycled Queenslander framing timber and a multitude of other wood. Anyway I've tried to sharpen them with a file which only made a marginal difference. They will be going in the bin as soon as I can find someone who is keen to sell me a 'used once' set like the below for 1/2 the RRP

Screen Shot 2020-08-12 at 9.46.43 pm.jpg

My new set will get the treatment they deserve with my new found knowledge.