3 inch holes in 3/4 inch MDF

[GeorgeO]

Folks

I need to drill a bunch of 2 and 3 inch holes for the inner braces in my new project. My carpenter can do the 2 inch ones, says a cutter for the 3 inch ones will cost about 700. Any suggestions abou twhat other options I may have for doing this?

 

[gobble]

If you visit SP road area, on the main road parallel to SP road there is a shop or two that will sell you 3" bits. A full kit of varying sizes should cost 700 or less so dont pay him 700 for a single piece. One shop is possibly called "Hindustan... " I may be wrong my recollection is faint.

3" will be a forstner bit but the local market does not know the word for it. They call it a "blind hole" drill bit the most common use for which is to carve the cup into which a closet hinge is is affixed. Others might try to sell you a hole saw which is slightly different but may also be used. Hole saw should be 50 bucks. The Forstner may be 100 a piece.

HTH
--G0bble

 

[GeorgeO]

Thanks Rahul

 

[quad]

George, I used a small piece of 3" PVC water pipe to mark the
hole with a sketch pen, and the neighbourhood carpenter
cut them on his jig saw for Rs 10 a hole. No need for such an
expensive hole saw bit.

The holes came out fairly ok.
Since they are for the inner brace only, absolute accurace/roundness
is not so important, so I think this will for you.

 

[t.antony]

If the idea is to attach to the hand drill then a hole saw is the better choice. A 3" forstner will be difficult to hold in place and there are more chances that the outcome will be a elliptical or teardrop shape.

A perfect circular cut contributes better towards the stiffness of the brace compared to an unsymmetrical cut.

 

[Thad E Ginathom]

the neighbourhood carpenter
cut them on his jig saw for Rs 10 a hole.

That's what I'd do too --- because I have a (hand-held) jigsaw already. Frankly, I am a poor carpenter, but with care and patience a perfect circle is possible.

 

[gobble]

If the idea is to attach to the hand drill then a hole saw is the better choice. A 3" forstner will be difficult to hold in place and there are more chances that the outcome will be a elliptical or teardrop shape.

A perfect circular cut contributes better towards the stiffness of the brace compared to an unsymmetrical cut.

Very good advice. A hnd drill not supported by a standmount/drill press may wander.

Better to find a local wood worker.

--g0bble

 

[sunilj]

Take the total area, calculate the circular bit and re-calculate for a square lattice.

 

[ontherocks]

If the idea is to attach to the hand drill then a hole saw is the better choice. A 3" forstner will be difficult to hold in place and there are more chances that the outcome will be a elliptical or teardrop shape.

A perfect circular cut contributes better towards the stiffness of the brace compared to an unsymmetrical cut.

Very good advice. A hnd drill not supported by a standmount/drill press may wander.

Better to find a local wood worker.

--g0bble

Its not like that.
More than an inch in diameter circular hole sawss have a 5mm drill bit at the center as a guide. This 5mm drill bit first drills a hole in the material and becomes the center & guide for the larger hole. That's how you use them with a hand drill.
I bought a box set of 7 such saws in Rs.160. It comes out pretty neat.

 

[Anil kumar]

3 inch hole saw is available at any leading hardware stores, they sell it separately, i have one.


Regards,
Anil

 

[Santy]

This is what I used for my custom rack. It cannot be Rs.700 for sure. Should e available for less than Rs. 150. But why buy new one, check with a nearby furniture shop. They can do it for some meager charges.

 

[miroflex]

Folks

I need to drill a bunch of 2 and 3 inch holes for the inner braces in my new project. My carpenter can do the 2 inch ones, says a cutter for the 3 inch ones will cost about 700. Any suggestions abou twhat other options I may have for doing this?

Hi George,

As a keen fretworker in the 1960s. I used to drill fine holes with a hand drill, pass a fretsaw blade through it, fix the blade in the fretsaw and cut out the larger holes drawn on the plywood/wood with a compass and pencil. A fretsaw is like a very fine jigsaw.

I am not sure whether fretsaws and fretsaw blades are still available in India but fretworking is a popular hobby in the U.K. with a monthly magazines called Hobbies Monthly being brought out by Hobbies Limited of Dereham, Norfolk. Old issues of Hobbies Weekly are regularly on sale on ebay.co.uk.

Regards.

 

[quad]

I am not sure whether fretsaws and fretsaw blades are still available in India but fretworking is a popular hobby in the U.K. with a monthly magazines called Hobbies Monthly being brought out by Hobbies Limited of Dereham, Norfolk. Old issues of Hobbies Weekly are regularly on sale on ebay.co.uk.

Regards.

I still use a hand fretsaw for many little holes. These days, a
dremel has taken over some of the lighter tasks.

I never thought I'd find anyone else who read Hobbies Weekly.
My dad had a collection from the 60s and I lusted for the
fret saw treadle they used to advertise. They had a DIY
radio column in it (I think by John Linsely Hood) and that's
how I got interested in electronics first. I still have a bunch of the mags.
The late 60s glossy version of Hobbies was never as good
as the old newsprint-style-paper weekly, IMO.

 

[miroflex]

I still use a hand fretsaw for many little holes. These days, a dremel has taken over some of the lighter tasks.

I never thought I'd find anyone else who read Hobbies Weekly.
My dad had a collection from the 60s and I lusted for the
fret saw treadle they used to advertise. They had a DIY
radio column in it (I think by John Linsely Hood) and that's
how I got interested in electronics first. I still have a bunch of the mags.
The late 60s glossy version of Hobbies was never as good
as the old newsprint-style-paper weekly, IMO.

Hi Quad,

My uncle owned a Hobbies Gem treadle operated fretsaw machine like the one in your picture, which was allowed to rust away. I would love to own one if such machines are still available. Please let me know if such a machine is available anywhere and is in your knowledge.

I did inherit a fretsaw with a toggle lever frame and Hobbies Blue Label fretsaw blades that could take a greater tension than Indian blades. There were also simple twist drills of the Archimedean type and drill bits of diamond pattern.

There were many green on yellowing paper plans of fretworking projects taken from old issues of Hobbies Weekly with which they were issued as supplements. Also two or three Hobbies Annuals and a few copies of Hobbies Weekly from the 1930s.

I hope we have not gone too much off topic.

Regards.

 

[GeorgeO]

No, no- relax,this is very much on topic..