Drilling a 4 inch hole

[Toolong]

5 hours ago, sometimewoodworker said:

I have one (though not the double cutter version) and the comments are from experience.

 

The careful to try is required in a drill press as the potential for grabbing the material is high.

 

The yellow saw is of questionable quality ThaiCarpenter stocks the Makita brand that is definitely good quality. However that kind of saw doesn’t have good chip removal which is why the TCT tipped tools are better, you are almost certainly going to want to cut a cement based board and even a high quality many toothed saw will be trashed quickly.

all the tools I have suggested are available, though the set under is better obtained from china 

Yes, the 'material grabbing'....I can see how that might happen....and get a bit tricky! ????

 

Gotta say, sometimeswoodworker, you know your stuff when it comes to tools of this kind, certainly more than I do. 

 

You mentioned me perhaps wanting, in the future, to cut a 'cement based board'. I'm not sure what you mean by 'cement based' board. For this job on my eaves I'm assuming I would be cutting through plaster board. I thought that would be quite soft, easily-drillable material. But then I am rather inexperienced in this area. (Actually, VERY inexperienced ????!)

 

I appreciate your help & advice. ???? 

[Toolong]

5 hours ago, Artisi said:

can't help with price but used a lot by sparkies for downlight holes - seek out a local sparky and see what they have or ask them to do the job for you.

Just learned a new term: 'downlight holes'! Didn't have a clue at first but yes, I get you! ????

Yes, if that drills good for 'downlight holes', then it could do my job.

 

Good to know. Thanks Artisi. ????

[Toolong]

4 hours ago, sometimewoodworker said:

They are easy to find with an image search on Lazada 

Hey, the prices are not bad! Certainly within my limited budget! ????

 

Seriously, thanks. Good to know. ????

[Toolong]

2 hours ago, Kwasaki said:

If the 4 in round vents have a border,  what i did with 3 in one's was drew a circle and with 6 mm drill just drilled around the inner circle and wood chiselled the holes require, i was in no rush. 

Now that's resourceful of you, Kwasaki. It did the job! Good for you. 

 

Funny....but I did kind of wonder if I could do something like that. Well, exactly that, actually. But I figured doing that 15+ times was too daunting! It would put me in my grave!

 

However....I do like your comment: 'I was in no rush'. ???? In a world of 'all rush, get nowhere', that's cool. ????

[degrub]

#1 piece of advice for large diameter hole saws, particularly if you are standing on a ladder, let the tool do the work. Keep the pressure at just enough to make dust. You will get cleaner holes drilled and are less likely to throw yourself off balance. Use a N95 or KN95 dust mask as you will be right under or next to the hole when you drill.

 

Cement board dust is similar to asbestos dust in its effects on lung tissue

[Toolong]

2 minutes ago, degrub said:

#1 piece of advice for large diameter hole saws, particularly if you are standing on a ladder, let the tool do the work. Keep the pressure at just enough to make dust. You will get cleaner holes drilled and are less likely to throw yourself off balance. Use a N95 or KN95 dust mask as you will be right under or next to the hole when you drill.

You've done this before, haven't you? ????

 

You obviously speak from experience, which is helpful and good to know. I am a bit careless up ladders at times! In fact, for me, ladders + drilling upward = potential disaster, as a rule. ????????

 

So I'll bear your advice in mind, degrub! Thanks. Appreciate it! ????????

[Elkski]

I have both types of these drill bits and have used them both many times.   In the USA that adjustable one comes with plastic dust collector bowls and we use them on soft drywall usually a I've the head.   They work well if you have the 2 cutters adjusted at the same radius.  I would not use that but to cut even soft wood but I never tried that with a 2 cutter large dia but.  But I do have a smaller one that cuts up to 2" hole in wood and using a drill press is common sense.    There is a quality difference and how long they will last and how good of a hole you can cut.   I think perfect for soffit holes.  I would put them every 50 cm or best to calculate the number needed for the volume of your attic.  The small vents have a opening area specification.  Need as much  inlet area as exhaust.   Hard to get to much in a warm climate. 

[whaleboneman]

1 hour ago, Toolong said:

Yes, the 'material grabbing'....I can see how that might happen....and get a bit tricky! ????

 

Gotta say, sometimeswoodworker, you know your stuff when it comes to tools of this kind, certainly more than I do. 

 

You mentioned me perhaps wanting, in the future, to cut a 'cement based board'. I'm not sure what you mean by 'cement based' board. For this job on my eaves I'm assuming I would be cutting through plaster board. I thought that would be quite soft, easily-drillable material. But then I am rather inexperienced in this area. (Actually, VERY inexperienced ????!)

 

I appreciate your help & advice. ???? 

Most soffit board here is cement based and extremely difficult to drill. I tried before and decided it was easier to replace all the solid soffit boards with the pre drilled boards.

[degrub]

Carbide tipped is what i have used for cement board straight cuts. Not sure of availability there for hole saws.

 

i tend to agree the safest alteritive is to replace with pre cut and pre painted soffit . Maybe hire it done in this case. 

[Toolong]

28 minutes ago, whaleboneman said:

Most soffit board here is cement based and extremely difficult to drill. I tried before and decided it was easier to replace all the solid soffit boards with the pre drilled boards.

Well, I did NOT know that. That the boards are cement-based, I mean. Interesting!

I thought drilling would be a piece of cake! Looks like I was wrong about that!

 

Oh......time to reassess options. ????

 

Thank you, whaleboneman. ????

 

[Toolong]

37 minutes ago, Elkski said:

I have both types of these drill bits and have used them both many times.   In the USA that adjustable one comes with plastic dust collector bowls and we use them on soft drywall usually a I've the head.   They work well if you have the 2 cutters adjusted at the same radius.  I would not use that but to cut even soft wood but I never tried that with a 2 cutter large dia but.  But I do have a smaller one that cuts up to 2" hole in wood and using a drill press is common sense.    There is a quality difference and how long they will last and how good of a hole you can cut.   I think perfect for soffit holes.  I would put them every 50 cm or best to calculate the number needed for the volume of your attic.  The small vents have a opening area specification.  Need as much  inlet area as exhaust.   Hard to get to much in a warm climate. 

Thanks Elkski......????...what you say is interesting & useful. 

 

Recommendations from people with experience of using such tools is always valuable. 

 

I appreciate your comment. ????????

[degrub]

If you can remove the existing solid soffit, i expect one coul use a carbide tipped skill saw and insertion cut slots in the board.  Not worth the time in my book.  Once down, easy to replace with vented soffit.

[Toolong]

21 minutes ago, degrub said:

Carbide tipped is what i have used for cement board straight cuts. Not sure of availability there for hole saws.

 

i tend to agree the safest alteritive is to replace with pre cut and pre painted soffit . Maybe hire it done in this case. 

Very interesting. Your recommendation means a radical change of plan, but I'm beginning to think you might be right.

 

I did not fully realise how much I do NOT know about soffit boards!!! ????????

 

But I really appreciate your input, degrub!  Thank you????

[Toolong]

1 minute ago, degrub said:

If you can remove the existing solid soffit, i expect one coul use a carbide tipped skill saw and insertion cut slots in the board.  Not worth the time in my book.  Once down, easy to replace with vented soffit.

Yes, as you say, not worth the time. Easier to replace with right stuff. 

 

Well.....this is a real roller-coaster ride (for me) of learning about soffit board!!! 

 

Thanks again degrub. ????

[degrub]

If a ridge vent is used, the soffit slots are used to set up a thermosyphon effect under the bottom roof surface. Generally, you want equal vent  area at the roof peak and at the soffit. You also want the soffit area distributed  evenly in the spaces between the rafters. A few round holes will probably work ok, but will not be optimal for getting maximum flow under the roof .

 

if there is not a ridge vent,  then the holes and placement will not matter as much, just make sure you have roughly equal area at the vent and the soffit inlet.

 

If the vent is powered, the manufacturer should provide a guide for soffit vent area required.

[sometimewoodworker]

2 hours ago, Toolong said:

You mentioned me perhaps wanting, in the future, to cut a 'cement based board'. I'm not sure what you mean by 'cement based' board. For this job on my eaves I'm assuming I would be cutting through plaster board. I thought that would be quite soft, easily-drillable material. But then I am rather inexperienced in this area. (Actually, VERY inexperienced ????!)

 

As has been mentioned, though possibly not in sufficient detail. Your soffits will not be plasterboard unless the job was badly botched. Plasterboard will disintegrate, the paper backing will be termite food and the moisture will do fun things to the boards. 
Plasterboard is not remotely water resistant and soffits get wet. So the wise use a waterproof or at least water resistant board and the cheap easy ones are cement based.

[sometimewoodworker]

44 minutes ago, degrub said:

Carbide tipped is what i have used for cement board straight cuts. Not sure of availability there for hole saws.

If you look carefully TCT hole saws are reasonably easy to find.

[degrub]

Yes, i see some now. 

[Toolong]

8 hours ago, sometimewoodworker said:

As has been mentioned, though possibly not in sufficient detail. Your soffits will not be plasterboard unless the job was badly botched. Plasterboard will disintegrate, the paper backing will be termite food and the moisture will do fun things to the boards. 
Plasterboard is not remotely water resistant and soffits get wet. So the wise use a waterproof or at least water resistant board and the cheap easy ones are cement based.

Yes, this is an example of how assumptions (mine) can be so wrong! ????

 

I thank you for giving me the detailed explanation of the differences in these materials. ????

 

As the existing solid boards (ie no vents) under my eaves are in good condition, I might still look into drilling or jig-sawing and adding vents myself....or....replace with pre-vented boards. 

 

Will do a cost-efficiency + labour-involved analysis, as best I can!

 

Cheers! ????????

[sometimewoodworker]

2 hours ago, Toolong said:

As the existing solid boards (ie no vents) under my eaves are in good condition, I might still look into drilling or jig-sawing and adding vents myself....or....replace with pre-vented boards. 

I have both a jigsaw and hole saws. It seems that you haven’t used either much, or at all. 
 

Someone who is experienced with using a jigsaw, but no hole saws might possibly choose to use one inverted, overhead, on a scaffolding platform, they may even get correctly sized holes and avoid all supports and produce a good job. This is something I would never consider as a good idea unless there were no other options.

 

TLDR hole saw or replace with vented boards.

[Kwasaki]

3 hours ago, Toolong said:

Yes, this is an example of how assumptions (mine) can be so wrong! ????

 

I thank you for giving me the detailed explanation of the differences in these materials. ????

 

As the existing solid boards (ie no vents) under my eaves are in good condition, I might still look into drilling or jig-sawing and adding vents myself....or....replace with pre-vented boards. 

 

Will do a cost-efficiency + labour-involved analysis, as best I can!

 

Cheers! ????????

With safe access equipment,  ladder,  or suitable steps it's an easy job cutting holes in soffit board with all sorts of ways of cutting the hole.

Just do it yourself or get someone to do it for you.

[Toolong]

3 hours ago, sometimewoodworker said:

I have both a jigsaw and hole saws. It seems that you haven’t used either much, or at all. 
 

Someone who is experienced with using a jigsaw, but no hole saws might possibly choose to use one inverted, overhead, on a scaffolding platform, they may even get correctly sized holes and avoid all supports and produce a good job. This is something I would never consider as a good idea unless there were no other options.

 

TLDR hole saw or replace with vented boards.

Yes, you're spot-on about my inexperience with jig-saws. ????

 

What I've learned over the past 24 hours, thanks to you & others, is that my sensible options are summed up in your final sentence above.

 

Thanks.????????

[Toolong]

2 hours ago, Kwasaki said:

With safe access equipment,  ladder,  or suitable steps it's an easy job cutting holes in soffit board with all sorts of ways of cutting the hole.

Just do it yourself or get someone to do it for you.

Agree about needing safe equipment! I have good ladders, but would love to own a simple, reasonably priced platform scaffold rig, for use when the space allows. ????

[Kwasaki]

1 hour ago, Toolong said:

Agree about needing safe equipment! I have good ladders, but would love to own a simple, reasonably priced platform scaffold rig, for use when the space allows. ????

Global house and many places can buy towers to erect but mostly I borrow a ladder if that's not suitable get someone to build a bamboo scaffold to suit the place of work or hire scaffold tower from local govt works department.

[sometimewoodworker]

2 hours ago, Toolong said:

Agree about needing safe equipment! I have good ladders, but would love to own a simple, reasonably priced platform scaffold rig, for use when the space allows. ????

They are reasonably priced and easily available 

[unheard]

19 hours ago, degrub said:

If a ridge vent is used, the soffit slots are used to set up a thermosyphon effect under the bottom roof surface

The OP hasn't mentioned what kind of the roof exhaust he's talking about if any.

If there are no openings in the upper area of the roof or if they're relatively small then there's no any need for any additional soffit holes.

[Toolong]

6 hours ago, Kwasaki said:

Global house and many places can buy towers to erect but mostly I borrow a ladder if that's not suitable get someone to build a bamboo scaffold to suit the place of work or hire scaffold tower from local govt works department.

I agree. Borrow if you can, or be resourceful and make your own (or have it made), or hire if it's cost efficient to do so.

But I kind of like the really functional, practical design of the metal rig-ups you often see on sites. 

 

But you're right and I mostly do as you do! ????????

[Toolong]

4 hours ago, sometimewoodworker said:

They are reasonably priced and easily available 

Thanks for sending the pics, sometimeswoodworker! I appreciate it. ????

 

That price is tempting. For my single-storey bungalow that would be sufficient. Add to later as needed, if needed at all. 

 

Now to convince my wife we absolutely must get one! ????????

[Toolong]

2 hours ago, unheard said:

The OP hasn't mentioned what kind of the roof exhaust he's talking about if any.

If there are no openings in the upper area of the roof or if they're relatively small then there's no any need for any additional soffit holes.

You know, unheard?

 

I was kind of wondering the same thing. I'm no expert on matters related to thermal/ air flow business, but no, I don't have what you call a 'roof exhaust' (ie, whirybird turbine, right?) and I know heat rises, so something did seem to me to be not ideal about soffit vents that to some extent actually allow heat IN as well as out (or am I completely wrong about that? I could be!), without a means by which that heat can be released  higher up as it rises.

 

I dunno. I'm still learning the basics! ????