Which Forstner Bit

[iron bark]

Morning all,

I am very new to turning and am teaching myself slowly - I did a couple of S & P grinders from cedar the other day and am still a bit unsure of the drilling - what is the best type of forstner bit to purchase - saw tooth or other:( ?

I got one saw tooth (38mm), and find it gets very hot whilst drilling - almost to the point of bluing - am I drilling too fast, or using the wrong type of bit or both?

Would appreciate any advice from all that experience out there.

Is there a turner group on the Sushine Coast??

Cheers,

Ned

[DJ’s Timber]

Saw tooth is for endgrain whilst the other type is for crossgrain.

For a 38mm bit you would be needing to go at about 300 to 400 rpm and a nice slow feed rate. It won't really make much difference to it getting really hot as there is a hell of alot of friction in there.

Slow and steady does it and you'll be right

Edit more info

I also use my airgun to blow out the shavings as well

[Gra]

forstner bits like to be inserted slowly, and a slow speed, basically as with turning, the bigger the lump, the slower you make it go round...

I usually set my lathe to its slowest speed, and clear the chips regularly. (Oh thats is the other important part, bring the bit out of the work on a regular basis, to help clear the chips out of the work)..

Good luck and show us some pics, remember it hasn't happened if there are no pics :D

[Rum Pig]

I am very new to Turning like you I don’t know much about the different types of Forstner bits:wink: but I do know that if you give them a quick sharpen before each use they do cut a lot easier and do not burn:) .<O:p</O:p
Apart from that I agree with what the rest say about slow and steady and withdrawing it regular to clear the waste:D .<O:p</O:p
There was an article in Australian woodworker on all the different types I will try and find it and relay any relevant info:2tsup: .<O:p</O:p
<O:p</O:p

Cheers Justin<O:p</O:p

[iron bark]

Thanks to all for the replies.

RP, do you sharpen sawtooth bits? If so, how do you do it - ie. do you sharpen all the saw teeth or just the main cutters - and do you sharpen the leading or trailing edge or both - sorry if these are dumb questions but I don't want to screw up my bits

Cheers,

Ned

[RETIRED]

http://www.woodworkforums.ubeaut.com.au/showthread.php?t=45453

[iron bark]

Thanks - very informative

Gra - pic of my first ever turning attempt - the different heights were intentional - the unrounded heads, well, they just turned out that way - I'll keep on trying to get them better - along with my photography - they actually do stand vertical - just not sitting on a flat surface - wood was some old cedar bits from the gold coast hinterland - collected about twenty years ago

Cheers,

Ned

[orraloon]

Ned,
What grinder innards are you using? 38mm is a big hole. I have only used the 7" ones and that requires a 7/8 hole or about 22mm. My old record lathe does not have the guts to use large diameter bits in any case. I also found that long stem drills flex a lot in my lathe but I guess this would be less in a bigger machine with a No2 morse taper.

Regards
John

[iron bark]

Ned,
What grinder innards are you using? 38mm is a big hole. I have only used the 7" ones and that requires a 7/8 hole or about 22mm. My old record lathe does not have the guts to use large diameter bits in any case. I also found that long stem drills flex a lot in my lathe but I guess this would be less in a bigger machine with a No2 morse taper.

Regards
John

John,

They came with the lathe when I bought it 2nd hand- Danish made 7" from Carba-tec - the main through hole is about 1", but needs the 38mm to fit the cross bar in the bottom - I purposely made the mills taller than specified so needed to bury the inards further up from the bottom

Cheers,

Ned

[orraloon]

Ned,
Have a try at enlarging the bottom recess with a scraper or a parting tool. Will leave a better cut than the drill bit. Tool must be sharp and take light cuts. Will be better centered too as drills can wander.

Regards
John

[iron bark]

Thanks John, I will give it a go

Currently working on a pair of grinders in iron bark - man is that hard timber so will probably have to use the forstner bit on that - but it polishes up beautifully - the cost being more time sharpening

[Rum Pig]

You may enough info already but I will give you some more that I have found and will still look up Australian woodsmith mag for you. If you want have a look at these links:) . http://www.ostartools.com/products/forwood/forstnerbits/forstnerbits.htm (http://www.ostartools.com/products/forwood/forstnerbits/forstnerbits.htm)
http://www.woodcraft.com/articles.aspx?articleid=380 (http://www.woodcraft.com/articles.aspx?articleid=380)
All I have ever done is just a quick touch with a file on the chipper but I’m no expert so it may be wrong but it has worked for me so far I do try to do it every other time I use them to keep them sharp:) . This has been with a drill press rather than a lathe but should be the same one would think.
<O:p</O:p
Cheers Justin

[turnerted]

Hi Ned
I agree with what everyone else said about drilling slowly and frequently clearing .I wont drill more than about 10mm without clearing .I wipe a finger in sawdust on the advancing centre of my tailstock to keep track of how much I have drilled . Don't wind it out each time to clear it , just unlock the tail stock and slide it out and in without turning off the lathe . The first time I drilled a vase prior to hollowing it I didn't clear enough and ended up jambing the bit and had to split the potential vase in half to recover my bit .I have also found that a squirt of WD40 on the drill each time I withdraw it helps but you may not want to do this with something in contact with food .

Ted

[DJ’s Timber]

Thanks John, I will give it a go

Currently working on a pair of grinders in iron bark - man is that hard timber so will probably have to use the forstner bit on that - but it polishes up beautifully - the cost being more time sharpening

You will definitely be using forstner sawtooth bits for the ironbark.

Here's a pair (http://www.woodworkforums.com/attachment.php?attachmentid=38693&d=1169356596) I made out of Blackwood and she took awhile to bore out. They are around about 330mm high.

[iron bark]

DJ,

Firstly they look magnificent - well done

Drilled my first iron bark grinder tonight - with the sawtooth forstener - took a while but got it done without too much heat buid-up.

I found that feeding the bit into the hole left by the centre caused the lot to go slightly out of centre - will have to be more careful with the next one

Cheers,

NED

[soundman]

If you doing a bit of this sort of stuff you might consider a couple of the carbide tipped boreing bits, they cut cleaner and they certainly handle the heat better.

I consider the normal carbon steel forstener bits " an ocasional use item".
They realy don't drill anything fast, they are easily overheated and need constant sharpening.

BTW thay usualy aren't sharp out of the box.

I've fettled a few of the sizes I've used a couple of times in my set.... and they go a lot better afterwards.
paying attention to the sharpening angles, relief angles and opening up the chip ejection slots helps heaps.

I've baught 3 sizes of carbide bits that I use often & there is a big difference.... much less pussyfooting..... you can just hop in a bore it up em:D

cheers

[iron bark]

Soundman, thanks for the advice- just looking at the Carba-tec cattledog and I asume you are referring to the TCT augers they have

Any views on carbon vs HSS forstner bits - its just that what I can see in augers are all too long and the biggest listed is 32mm

Could you also tell this dumb&rse how you fettle them please

Thanks,

Ned

[Wild Dingo]

You use forstner bits on da lathe??????? :o :o :o :o

oooh why is my mangled finger suddenly hurting like a demented wombat? :C

[RETIRED]

You use forstner bits on da lathe??????? :o :o :o :o

oooh why is my mangled finger suddenly hurting like a demented wombat? :CFrequently. It is just a horizontal drill press.:D

[tashammer]

a short, thick, furry finger with tics that makes hissing noises?

i hope that you haven't been playing with that DIY Genetics kit again have you Wild Dingo cum Wombat Bits

[Mobil Man]

Try starting with a small bit & working up thru larger sizes until you get to the size hole you want. That way, each bit is only cutting small amounts of wood.

[RETIRED]

Try starting with a small bit & working up thru larger sizes until you get to the size hole you want. That way, each bit is only cutting small amounts of wood.Not with Forstners or any other wood drilling bit!!

It is a recipe for disater as the centre locating pin has nothing to hold against.

[Gra]

You use forstner bits on da lathe??????? :o :o :o :o

oooh why is my mangled finger suddenly hurting like a demented wombat? :C

Nothing wrong with that. Forstner bit in a chuck in the tail stock. timber mounted in the chuck at the other end. lathe on slow bring the tail stock close to the timber, wind out tail stock...

No hands near the bit, you can even stand behind the tailstock

[Wild Dingo]

Nothing wrong with that. Forstner bit in a chuck in the tail stock. timber mounted in the chuck at the other end. lathe on slow bring the tail stock close to the timber, wind out tail stock...

No hands near the bit, you can even stand behind the tailstock

now theres a relief!! :2tsup:

still...

I dont know...

my records not to snazzy just lately :doh:

[Skew ChiDAMN!!]

a short, thick, furry finger with tics that makes hissing noises?

i hope that you haven't been playing with that DIY Genetics kit again have you Wild Dingo cum Wombat Bits

Maybe he means it's gone a fuzzy grey colour that leaks stinky fluids all over the place? Dingo, mate, loosen the knot in the bandage!

[soundman]

The bits I was talking about are not auger bits. They are carbide tipped versions of sort of resembling a forstener. they have two scoring cutters and two planing cutters, often refered to a hinge sinking bits.. usualy grouped with the router bits.....look for the caption....."NOT FOR USE IN ROUTERS" and youve probaly found them:D

cheers

[iron bark]

OK, with you now - CMT - not all that cheap, but if they do the job and last, then they are worth it.

Would still like a heads up on your fettling technique though, or a link if it has been up before.

Thanks,

Ned

[soundman]

There are cheaper ones to be had.

the fettling technique
make sure all the cutting edges are in fact sharp.... a smalll mill file & trianguar files will sort those out.
Most of the bits you will see that the idea was there but... sharp just didn't happen...... make it so.

one big improvement, particularly in the smaller bits is to make sure the chip chhannel is clean, smooth and not a converging taper.

I had a small bit that just clogged hopelessly..... the chip channel was rough and tapered inward.
a few minutes with a file and it was a diferent bit

cheers

[iron bark]

Many thanks Soundman - it makes sense when you think about it - I am only just after all these years learning the pleasures of using really sharp tools - thanks go to many others on this forum for the "good oil"

cheers,

Ned

[Frank&Earnest]

Hi all. I am taking a TAFE beginners' course in woodturning (basically access to good lathes and the brain of a good turner) and used the drilling bit (38mm i think). Probably blunt, it was hard going and almost red after just 160mm of careful drilling in soft pine, but it did the job.

IMHO for these jobs it would be much better to just take the piece off and use a decent drill press instead of asking the lathe to do something that is not its core function. Any comments?

[TTIT]

Hi all. I am taking a TAFE beginners' course in woodturning (basically access to good lathes and the brain of a good turner) and used the drilling bit (38mm i think). Probably blunt, it was hard going and almost red after just 160mm of careful drilling in soft pine, but it did the job.

IMHO for these jobs it would be much better to just take the piece off and use a decent drill press instead of asking the lathe to do something that is not its core function. Any comments?
Can't agree on that one Frank - depends on the lathe. Most drill presses are only rated about 3/4HP amd most lathes are rated higher. Speeds can be adjusted to roughly the same ranges. Winding the bit in with the tailstock and winding it down on the press aren't much different. I find the best thing to do is feed the bit into the wood fast :o Don't give it time to rub and burn - keep feeding it cool timber - much the same as you would on a drill press actually - works for me! :shrug:

[Frank&Earnest]

Hi TTIT. No argument with anything you say. The point of the matter though is whether the agreed small difference between the horizontal and vertical action does indeed result in a noticeable advantage for the vertical. I am no physics genius and could not put it down in formulae, but my bet is that eliminating the effects of gravity, centrifugal force and lateral leverage against the chuck due to even minimal misalignment should provide such an advantage. Of course, the smaller the piece the smaller the difference, to the point that for most applications it might well be not worth the hassle of dismounting/remounting. Does it make sense in these terms?

[DJ’s Timber]

I find that the lathe will drill more accurately than the drill press even with my 250mm extension bar

[Skew ChiDAMN!!]

Of course, the smaller the piece the smaller the difference, to the point that for most applications it might well be not worth the hassle of dismounting/remounting. Does it make sense in these terms?

I've found that in practice it doesn't work that way. Removing a piece from the lathe, drilling on the press and returning to the lathe will always (in my experience) introduce larger centering errors than just drilling on the lathe in the first place.

Drilling first and then centering has it's own problems, as there's no guarantee that the headstock end of the bore will be centred in the chuck. I've tried using a centering pin in the chuck, but then there's no guarantee that the pressure applied by each individual jaw will be equal... and that can cause yet other problems. To work around this, I've tried drilling first, mounting between conical drive spurs (to centre the bore) and trued the tenon for the chuck... but still had centering errors when rechucking. :shrug: C'est la vie.

And the smaller the piece, the greater the error in relation to the size overall.

No, I drill on the lathe. Much simpler and more accurate... for me.

[joe greiner]

I posted a brief dissertation on Forstner bits here:

http://www.woodworkforums.ubeaut.com.au/showthread.php?t=44107

The problem with drilling end grain with Forstner bits is the cleanout chisels cutting across grain. The forward/reverse sizing procedure I described is more appropriate to the drill press, especially if the workpiece is hand-held. If the workpiece is rigidly mounted to the table, working directly up from a smaller bit works because the bit doesn't need the centering point. Same thing on the lathe. For deep holes, the lathe works better because it maintains the center location when you relocate the tailstock. Not so with the drill press; when you release the table for elevation change, you usually also release the center location.

Joe

[Frank&Earnest]

OK, so much for my theory. I bow to the masters :B.

ETA: on the other hand, asking turners to betray their loved ones was silly of me, wasn't it? :roll:

[soundman]

It is common not only in woodturning but also in metal fitting and machining to drill in the lathe.
there are substantial techincal and safety advantages for doing so.

One point to consider is that the traditional forstener bit may not be the best tool for drilling end grain as mentioned earlier.

I think we use them because they are easily available in the sizes we want.

I think it is probable that a traditional or modified twist bit would be a better performer drilling medium depth holes in end grain.
Large twist bits ( up to an inch) can be easily and cheaply obtained.
That covers some of the salt shaker/ pepper mill work.

The carbide tipped hinge sinker bits previously mentioned will certainly cop the pace better than the traditional forstener.

cheers

[iron bark]

Soundman,

Any idea where to get those bits you were talking about apart from the fairly pricey CMT bits at C/tec - are they available in Brisbane??

Thanks,

Ned

[soundman]

Carbatec used to have a range of them in their own brand generic range. I've picked most of mine up off the specials table.
most saw doctors will have at least a couple of sizes for sinking euro cabinet hinges.
try.
peacock saws
brisbane saw service
carbatec of course..... brisbane particularly has lots of stuff that isn't in the catalogue.
I havn't looked at the other usual suspects like timbecon, GPW, carroll's, McJing, but they may be worth a try.
I'm sure carbatec ( at one time) used to do small sets of 5 or so, in generic.

I can certainly supply BIG twist bits if you are looking for those..... I havn't been paying much attention to "Soundman INC" lately.... must get back on it.

cheers

cheers

[rsser]

Just been wondering about TCT bits and searched the forum to get some feedback on them. Thanks soundman. Do you find that they work as cleanly as sawtooth bits on endgrain? Are you using CMT or Torquata or something else?

Sources:
http://www.timbecon.com.au/products/forstner-style-bits-367_0.aspx
http://www.carbatec.com.au/store/index.php?main_page=index&cPath=100_9030_9040_9081

Carbatec also have HSS forstners and sawtooth bits. I've been using a 2" sawtooth version and it's worked well but I find it a good deal more work to sharpen.

[soundman]

the carbide bits are evey bit as clean as the conventional bits possibly better on face grain. I haven't had reason to use then on end grain at this point.

the bits I have are generic items some from carbatec some from other places.

cheers

[rsser]

Just found McJing have TCT, HSS, and TiN coated.

Any experience with TiN?

Presumably they're not sharpenable.

They also have an MT2 extension with several collars now for Forstner/sawtooth bits.

[soundman]

there is no problem with sharpening titanium nitrided bits.
sharpen as usual. Being TiN coated should mean they are HSS which means you wont sharpen thm with a file.

TiN coating realy only gives a friction advantage on the front face of the cutting edge from what I've read. Does very little for hardness.

cheers

[rsser]

Thanks. I'll give a McJing TCT bit a try with end-grain boring. Finish isn't critical as mostly I do this to open up a pencil jar or box fast.