Saw tooth bits or Forstners...whats the diff?

[rafezetter]

I was looking at this set and is seems a great deal, but I've no real idea what the differences are in operation and useage between these and forstner bits. I would in all likelihood just use them instead of spade bits when I'm either overlapping or enlarging a small hole or where I want a flat bottom (no jokes please )

Anyone who have both can share some advice?

http://www.rutlands.co.uk/sp+woodwo...saw-tooth-bits-metric-set-of-16-dakota+dk2074

 

[andersonec]

I think there are various reasons for the saw teeth and I think it is something to do with preventing tear-out, pressure, cutting speed (RPM) and maybe some other stuff. Have a browse around the various types on the link and see if you can glean any information.

http://www.fine-tools.com/forstnerbohrer.html

Andy

 

[Mr T]

I think ordinary forstners are not very efficient in larger diameters, often leading to over heating, hence the teeth on larger sizes. The set shown, if you look closely at the smaller ones, I don't think they are saw tooth.

Chris

 

[rafezetter]

Thanks for that link Andy, very informative (although now I quite fancy some of the other things on that site!) - the saw tooth is simply a more efficient design over the basic smooth forstner; one of several different versions depending on application.

As it's normally £20 for 6 basic cutters, the offer of £40 for 16 with a more efficient design seems a no brainer.

 

[marcros]

I found these to be a decent set. http://m.screwfix.com/p/forstner-bits-1 ... tAodbnAAKA

They appear on offer from time to time- I think I got mine half price.

Don't be fooled by the rutlands list price, it doesn't make them £80 drill bits!

 

[Random Orbital Bob]

I was looking at this set and is seems a great deal, but I've no real idea what the differences are in operation and useage between these and forstner bits. I would in all likelihood just use them instead of spade bits when I'm either overlapping or enlarging a small hole or where I want a flat bottom (no jokes please )

Anyone who have both can share some advice?

http://www.rutlands.co.uk/sp+woodwo...saw-tooth-bits-metric-set-of-16-dakota+dk2074

Remember that European butter mountain in the 70's? Making these it what it got used for! They're the same as another Chaiwanese set that Axy do that I bought years ago. Absolutely useless! I've never come across a softer metal in all my life. Save your cash and buy individual cutters from Colt, Famag etc as and when you need them and you will never regret it. The difference in quality, longevity of the edge, accuracy of the resultant hole is like chalk n cheese.

 

[Noggsy]

I've used a few different cheapo forstner bits and as is said above, I wouldn't bother. The Fisch wave bits from Axi are more expensive, but the holes they cut are clean with no overheating. One thing you could do is buy a cheap set and grind the points off just to finish the last few mm of a hole where you've used a decent bit and don't want a centre point at the bottom. Having used decent bits, I would never buy cheap again - life's too short.

 

[gregmcateer]

I've used a few different cheapo forstner bits and as is said above, I wouldn't bother. The Fisch wave bits from Axi are more expensive, but the holes they cut are clean with no overheating.

+1 for that

 

[andersonec]

Thanks for that link Andy, very informative (although now I quite fancy some of the other things on that site!)

Sorry mate, but like some of the other guys I have bought one or two as I needed or could afford them and now have a good little set. Axminster do the Colt which saves a bomb on postage from the German firm but they do some sizes which are just not available anywhere else.

Andy