# Cutting 92mm holes through 6inches of oak...



## bristolwoodrecycling (16 Apr 2012)

Hello!

Newbie here, looking for some advice...

A client of mine wants me to cut up to 100+ holes through old, reclaimed oak beams to be used as wine racks.

The wholes are a whopping 92mm in diameter and the oak is up to 6inches thick. The client has supplied me with a 92mm Dewalt Forstner bit.

It is proving to be an absolute ball ache of a job and I am managing to churn out about 2 holes an hour. Un-economical for me and the client.

The thing which is slowing me down the most, is that the forstner bit requires sharpening after almost every hole!

I am using an old, but powerful (aprox 900W) pillar drill on its slowest speed. When the bit is newly sharpened, it can generally cope, but very quickly begins to struggle. The excessive heat generated sn't help the condition of the bit either.

Any tips on speeding it up? Different drill? Different bit?

Reaching crisis point!!


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## Von Ryan (16 Apr 2012)

Famag tct or hss boremax, try Workshop Heaven


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## Hudson Carpentry (16 Apr 2012)

92mm bit forsoner bit :shock: 

I would say a Hole Saw would be faster even if more involved. Either:

1. Drill a pilot hole first all the way through then use a 3"+ deep hole saw coming at it from both ends.
2. Drill from the one end if you can't get a 3"+ hole saw but once it hits full depth of cut, remove the saw, chisel out the "loose" bit then plunge the saw back in and continue and repeat until done. This could be done in batch. Cut to saw depth on the full length (each hole) take to bench and chisel all holes then back to drill.

This is assuming you can't get a 6" depth hole saw for timber, you can for masonry but not to sure for timber.


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## adidat (16 Apr 2012)

there is no easy way to do this job, your removing a lot of timber, something like english oak will dull a blade easily. have you thought about drilling a hole for the neck to go in instead?

adidat


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## Steve Blackdog (16 Apr 2012)

Welcome BWR, do stay on the forum to tell us your solution.

They are holes and a half! And Oak. It sounds well seasoned. Couldn't he have specified concrete - at least you could use a diamond core drill!

This is just a thought and may not work. How about drilling a dozen or so small holes in the oak (within the 92mm circle) trying not to hit the centre of the circle or the edge of the circle, so the area to be drilled looks like an Aero chocolate bar.

Then when you use the forstner, the bit will be doing very much less work and therefore logically should be much easier to cut.

With such a large bit you will need to go as slow as you can. The cutting outside edge will be going at a much higher speed that the centre. (think the blades on a wind turbine - the ends of the blades travel very much further than the axis) 

Lots of small cuts may help the heat, but I had real trouble yesterday with a 16mm plug cutter almost setting fire to a piece of very hard cherry - 92mm doesn't bear thinking about.

I don't want to upset you, but there must be a risk that if the cutter has become very hot such that it started bluing, it may be that the hardness has been lost, which might stop it holding a sharp edge.

Another wacky thought - someone else can shoot me for this - if this is basically a beam with holes in it, would it matter if you soaked it in water? Would that soften the wood and lubricate the cutter? 

I hope he buys decent wine to make this worthwhile.

Good luck

Steve


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## zb1 (16 Apr 2012)

I'd be inclined to mark out the holes and drill round the edge about 5mm in with a much smaller auger, say 10mm. Let the middle drop out then clamp the oak VERY securely in the pillar drill and only use the edge of the forstner to clean the hole to the exact diameter. 

What might be even better is to go in with the forstner about 5-10mm deep then drill out the edge then go back to the forstner after so that it is correctly centred.

I've done quite a few timber engineering jobs with green oak (for my sins) using upto 50mm forstners to rebate for washers and bolt heads, about 25mm either side. Takes an age and requires constant sharpening and more than one bit because you _will_ blue the edge and it will become useless. 

My sharpening tip is a chainsaw file for the dog teeth and use a fine file to quickly put an edge back on the cutter. 2-3 strokes will do.

Best of luck.


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## jasonB (17 Apr 2012)

Get it water jet cut if the wood can take the quick wetting 150mm depth won't be a problem if its only a wine rack.

If not have them CNC routed out provided you can get a long enough reach.

J


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## EssexChris (17 Apr 2012)

How accurate or smooth do the holes have to be along the full length of the bore?
Could you rough out the bulk of the material with a chain mortiser then tidy up from each end with a router and jig. 
This would save hours of drilling. 
Even if you had to hire one for a day.

Chris.


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## Hitch (17 Apr 2012)

Now, if you could get the 'plug' out every 2 inches, you could perhaps use a carbide tipped holesaw.....reasonably easy for the first 50mm.... then a bit harder I suppose.

Not sure how good the finish would be on that though, Ought to be half decent didn't it......?

http://www.tools4trade.com/d-1923024-st ... -92mm.aspx
This type of thing.


As I type, something else springs to mind.... the carbide tipped holesaws for masonry.....they do them in about 300mm deep dont they?

Almost wants doing on a metalworking type setup, in a mill or radial drill, with auto feed


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## bristolwoodrecycling (18 Apr 2012)

Wow! Thank you for all of your great responses!

I have now tried:

Cutting with a hole saw, 1 to 2 inches at a time and then chiselling out.
- Quite effective, but leaves quite a rough cut compared to the forstner, still takes the same amount of time - plus if I was to do more than a few I would need to start sharpening the hole saw and chisels.

Drilling around the pilot with various sized forstner bits to create an aero affect.

- Takes the strain off the 92 bit considerably, but drilling that many holes through that much wood takes almost the same amount of time.

Drilling straight through the middle with a 50mm bit, then following through with the 92.

- Probably the quickest way so far (marginally) but without the pilot it gets a bit shakey! Blade still blunts relatively frequently, but not as bad.


I think my options are:
a) Get the client to re-think his pricing structure, considerably!
b) Drilling a hole for the neck to go in instead (thanks adidat - a stroke of genius that one!)
c) CNC/Water Cutting -I have contacted a few local places to get quotes...watch this space
d) Telling him to shove his turnip oak where the sun don't shine...not so good for business

Thanks again for all your help...I will keep you updated...


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## Hudson Carpentry (18 Apr 2012)

bristolwoodrecycling":7u4qrja3 said:


> I think my options are:
> a) Get the client to re-think his pricing structure, considerably!
> b) Drilling a hole for the neck to go in instead (thanks adidat - a stroke of genius that one!)
> c) CNC/Water Cutting -I have contacted a few local places to get quotes...watch this space
> *d) Telling him to shove his turnip oak where the sun don't shine...not so good for business*



=D> That did make me laugh and after two posts you have found a word that the square filter didn't catch


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## BelgianPhil (18 Apr 2012)

Hudson Carpentry":3ihfhp1q said:


> =D> That did make me laugh and after two posts you have found a word that the square filter didn't catch



Could it be because turnip is a legitimate word as in: turnip cut file ?

Phil


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## Hudson Carpentry (18 Apr 2012)

So is a turnip file like any other turnip tool, one that don't work or cut any more hehe


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## matthewwh (18 Apr 2012)

Sometimes the guy paying the bill can have a remarkably optimistic view of what is possible. 

Forstner was a gunsmith, which gives you an idea of the size of the holes and pieces of wood he had in mind, you are operating way outside of that territory and have done incredibly well to get as far as you have. 

At 6 inches a diamond core drill is probably the only realistic non-industrial option but they're not exactly cheap either.

I would suggest some version of d) that leaves him with a warm fuzzy feeling about abandoning the idea.


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## AndyT (18 Apr 2012)

I think there's an interesting lesson in design here. Your client, I presume, thinks he has designed a wine rack. But he hasn't. If it's not feasible to make it out of the materials available, it's a fantasy, not a design. Frankly I find the whole idea of a wine rack laughable, but one made out of a big heavy chunk of oak sounds like a waste of good materials. I hope he wasn't thinking of selling them as 'green' just because the wood was reclaimed.


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## Dusty (18 Apr 2012)

I think if it was green then I would be concerned if you drill 92mm holes , stick your expensive wine bottle in it and then the wood moves / shrinks , and voila the bottles are stuck in !! 

It is not a new idea as I remember seeing a picture of very similar but as posts made vertically .

Kind regards Sam


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## toolsntat (18 Apr 2012)

It's a real shame KWO don't do your size as they are the ultimate in hole boring kit 8) 
http://www.kwo.co.uk/pages/Duflex.html

You could give em a call :wink: 

Andy


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## Benchwayze (19 Apr 2012)

The guy who came to put a 'ventilation' hole in my lounge exterior wall, (Because of the gas fire and carbon monoxide) used a type of hole saw, in a deWalt cordless drill. The cutter looked like a TCT hole-saw to me, and was about 4" in diameter. He went though my cavity wall like it was butter. He did work from both sides, but I feel that was more an anti-breakout procedure than to make the job easier.


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## jasonB (19 Apr 2012)

TCT core drill would need regrinding as the tooth profile is completely wrong, just like using a masonary drill to drill wood.

Diamond core drills will just gum up and burn and won't clear the dust, though they do eventually grind there way through from past experiance

The ideal cutter would be the Rotabroach type ones that are used on magnetic drills but I had a look and they don't go upto 92mm stopping at about 3".

J


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## TrimTheKing (19 Apr 2012)

These guys manage it. I've got one of these, bought years ago when they first started out, and the holes are very smooth. 

Might be worth getting in contact and playing dumb, saying you have a lump and are looking make your own...

http://www.oakwineracks.co.uk/

Hope that helps

Cheers
Mark


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## Bradshaw Joinery (19 Apr 2012)

Difficult one.... 
http://www.toolstop.co.uk/starrett-fcw0 ... 2mm-p22721
Could try with this from the face with a pilot hole right through before hand. (use a long say 6mm auger as guide)
Then remove centre plug by any means ( could do a few them mortice a line through the middle of the holes and then break the half moon off with a bar/cold chisel/hammer.

Then on the back edge use a bigger cutter say 100mm to do the same. 

This will give the clearance for the 92mm bit as the spanner flats are proud of the cutting edge(they might mot be they just look like it)
This would leave you with 2" in the middle to use the 92mm cutter on. 

In actual fact, youd only need to remove the plug left from the back as the front would be removed when the cut goes through.


If it was me id just grind the spanner flats off and use the 92mm all the way.


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## Mr T (19 Apr 2012)

Now this could be a silly idea and I don't mind being told so, but how about ripping it down, band sawing lots of semi circles then sticking it back together. Not sure if a 6mm band saw would manage it.

Chris


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