It is currently 27 Feb 2020, 05:50

Drilling a 120mm dia hole

This forum is for any general questions, queries or plain old chinwaggery on Woody stuff in general.

Drilling a 120mm dia hole

Postby RogerS » 11 Feb 2020, 22:50

A friend of mine is the manager at one of the Roman forts up here. They've got a larch that's been felled, very straight and about 400mm dia. They want to cut it into 1m lengths and then make a hole 120mm down the middle and about 300mm + deep. He asked me how to do it and I've not got much of an idea. Huge lathe ? Some machinery a shipwright would have ?

Any ideas, chaps ?
Fewer Smart things. More smart people.
User avatar
RogerS
Sequoia
 
Posts: 6628
Joined: 21 Jul 2014, 21:07
Location: Nearly finished. OK OK...call me Pinocchio.
Name:

Re: Drilling a 120mm dia hole

Postby Woodbloke » 11 Feb 2020, 23:21

No idea but the Romans apparently used to bore out elm logs to carry water, which were then laid alongside their roads; hence the origin of the term 'trunk' road - Rob
I no longer work for Axminster Tools & Machinery.
User avatar
Woodbloke
Old Oak
 
Posts: 1786
Joined: 22 Jul 2014, 10:06
Location: Salisbury, UK
Name: Rob Stoakley

Re: Drilling a 120mm dia hole

Postby 9fingers » 12 Feb 2020, 08:54

How about laser or water jet specialists for high tech approaches?

Bob
Image
Information on induction motors here
https://drive.google.com/file/d/0B_GZrX ... sp=sharing
Email:motors@minchin.org.uk
User avatar
9fingers
Sequoia
 
Posts: 5512
Joined: 21 Jul 2014, 20:22
Location: Romsey Hampshire between Southampton and the New Forest
Name: Bob

Re: Drilling a 120mm dia hole

Postby Rod » 12 Feb 2020, 11:10

Burn out with hot rods.

Rod
User avatar
Rod
Old Oak
 
Posts: 4109
Joined: 21 Jul 2014, 21:34
Location: Winchester, Hampshire
Name:

Re: Drilling a 120mm dia hole

Postby StevieB » 12 Feb 2020, 12:19

I may be missing something here, but you can get core bits at 120mm diameter and extension bars for them to easily cope with 300mm depth - sure they are not designed to cut wood particularly, but as the timber will be wet and the 'teeth' on some of these things are large, I would definitely be giving this a go as a cheap and low tech solution.... or have I misunderstood what is required?
StevieB
Nordic Pine
 
Posts: 599
Joined: 21 Jul 2014, 21:47
Location: Chatteris, Cambridgeshire
Name:

Re: Drilling a 120mm dia hole

Postby Andyp » 12 Feb 2020, 12:21

Drill lots of smaller holes then chisel them out/together. Smoothing with a drum sander.
cheers

Andy
“Sometimes I sits and thinks, and sometimes I just sits...” A.A. Milne

Doing my best to achieve Wabi Sabi
User avatar
Andyp
Sequoia
 
Posts: 6071
Joined: 22 Jul 2014, 07:05
Location: 14860 Normandy, France
Name: Andy

Re: Drilling a 120mm dia hole

Postby Andyp » 12 Feb 2020, 12:22

StevieB wrote:I may be missing something here, but you can get core bits at 120mm diameter and extension bars for them to easily cope with 300mm depth - sure they are not designed to cut wood particularly, but as the timber will be wet and the 'teeth' on some of these things are large, I would definitely be giving this a go as a cheap and low tech solution.... or have I misunderstood what is required?


How would you snap off the core when it reaches the max depth of the bit?
cheers

Andy
“Sometimes I sits and thinks, and sometimes I just sits...” A.A. Milne

Doing my best to achieve Wabi Sabi
User avatar
Andyp
Sequoia
 
Posts: 6071
Joined: 22 Jul 2014, 07:05
Location: 14860 Normandy, France
Name: Andy

Re: Drilling a 120mm dia hole

Postby MY63 » 12 Feb 2020, 13:31

What you need is a man with a chainsaw sorry I don't know how to make the video work.

https://www.youtube.com/watch?v=w4356Um ... e=youtu.be



MOD EDIT : I've put the video into the post for you - Trim
MY63
Nordic Pine
 
Posts: 641
Joined: 17 Oct 2018, 20:41
Location: North East England
Name: Michael

Re: Drilling a 120mm dia hole

Postby StevieB » 13 Feb 2020, 11:20

Andyp wrote:
StevieB wrote:I may be missing something here, but you can get core bits at 120mm diameter and extension bars for them to easily cope with 300mm depth - sure they are not designed to cut wood particularly, but as the timber will be wet and the 'teeth' on some of these things are large, I would definitely be giving this a go as a cheap and low tech solution.... or have I misunderstood what is required?


How would you snap off the core when it reaches the max depth of the bit?


Chisel / spade bit / smaller drill etc - once you have the outer limit of the hole bored it should be relatively painless to remove the centre surely? It depends how flat you want the base of the hole I guess - what is the purpose of boring the hole in the first place Roger?
StevieB
Nordic Pine
 
Posts: 599
Joined: 21 Jul 2014, 21:47
Location: Chatteris, Cambridgeshire
Name:

Re: Drilling a 120mm dia hole

Postby Andyp » 13 Feb 2020, 11:42

StevieB wrote:
Andyp wrote:
StevieB wrote:I may be missing something here, but you can get core bits at 120mm diameter and extension bars for them to easily cope with 300mm depth - sure they are not designed to cut wood particularly, but as the timber will be wet and the 'teeth' on some of these things are large, I would definitely be giving this a go as a cheap and low tech solution.... or have I misunderstood what is required?


How would you snap off the core when it reaches the max depth of the bit?


Chisel / spade bit / smaller drill etc - once you have the outer limit of the hole bored it should be relatively painless to remove the centre surely? It depends how flat you want the base of the hole I guess - what is the purpose of boring the hole in the first place Roger?


Seems like a plan.

When are you going to start Roger?
cheers

Andy
“Sometimes I sits and thinks, and sometimes I just sits...” A.A. Milne

Doing my best to achieve Wabi Sabi
User avatar
Andyp
Sequoia
 
Posts: 6071
Joined: 22 Jul 2014, 07:05
Location: 14860 Normandy, France
Name: Andy

Re: Drilling a 120mm dia hole

Postby RogerS » 13 Feb 2020, 16:39

Andyp wrote:
StevieB wrote:
Andyp wrote:
How would you snap off the core when it reaches the max depth of the bit?


Chisel / spade bit / smaller drill etc - once you have the outer limit of the hole bored it should be relatively painless to remove the centre surely? It depends how flat you want the base of the hole I guess - what is the purpose of boring the hole in the first place Roger?


Seems like a plan.

When are you going to start Roger?


Not me, sunshine :lol:

The general consensus is to bandsaw it in half then use one of those grunty wood carving bits that go on a angle grinder. Hollow out as necessary. Maybe use a template to approximate to the required shape. Then glue and dowel back together with polyurethane. If I had a bigger bandsaw then I might have had a go.
Fewer Smart things. More smart people.
User avatar
RogerS
Sequoia
 
Posts: 6628
Joined: 21 Jul 2014, 21:07
Location: Nearly finished. OK OK...call me Pinocchio.
Name:

Re: Drilling a 120mm dia hole

Postby Andyp » 13 Feb 2020, 16:45

Shame you don't feel brave enough to upend a chainsaw as per the vid. :)

So whats it for?
cheers

Andy
“Sometimes I sits and thinks, and sometimes I just sits...” A.A. Milne

Doing my best to achieve Wabi Sabi
User avatar
Andyp
Sequoia
 
Posts: 6071
Joined: 22 Jul 2014, 07:05
Location: 14860 Normandy, France
Name: Andy

Re: Drilling a 120mm dia hole

Postby RogerS » 13 Feb 2020, 16:49

Andyp wrote:Shame you don't feel brave enough to upend a chainsaw as per the vid. :)

So whats it for?


I forgot to look at that video. Superb...especially the guarding.

It's to replicate the position of the uprights used in the medieval hall. They've got some concrete pads with vertical steels where they found the original (but rotten) uprights. Just wanted to improve the aesthetics .
Fewer Smart things. More smart people.
User avatar
RogerS
Sequoia
 
Posts: 6628
Joined: 21 Jul 2014, 21:07
Location: Nearly finished. OK OK...call me Pinocchio.
Name:

Re: Drilling a 120mm dia hole

Postby PitchPine » 15 Feb 2020, 23:57

I’m interested to find out how you do this. I have two ideas -

- Make / find someone to make an enormous Forster bit...

- Ask a machine shop with an oil country lathe to do it for you, they might laugh at first but it would be a quick job. Lots in my area.
PitchPine
Seedling
 
Posts: 16
Joined: 25 Nov 2019, 22:43
Name:

Re: Drilling a 120mm dia hole

Postby PitchPine » 16 Feb 2020, 00:54

PitchPine wrote:
- Make / find someone to make an enormous Forster bit...



Maybe a spade bit, easier than a forstner. I’d have a go at making one if your friend is interested.
PitchPine
Seedling
 
Posts: 16
Joined: 25 Nov 2019, 22:43
Name:


Return to General Woodworking

Who is online

Users browsing this forum: No registered users and 3 guests

cron