Hole Cutting

Would a spade bit work? Rather then a hole saw, as they don't have the depth, a spade drill bit may do the trick for you.

The spade bits will not hold up.

How about a template and a spiral saw?

There are (diamond) hole cutting saws for masonry..try a builders merchant .

Once again ..if you told us what continent you are on maybe we could help..!

If you are in UK.. 'Screwfix' have these things.

Are you guys with no profile paranoid or just lazy....?

Sorry but this is just soooo irritating...Hey you could add some unrecognisable acronyms into your post just to make me more grumpy.

Calm calm calm.... ahhhh.

Just a new user haven't had time to complete everything yet. The dept of cut is the biggest problem, not the actual cutting. Carbide works fine.

The ones I've seen for masonry are like a tube with raised sections at the end with the teeth on..they are deep enough to go through bricks and blocks...so should do the job...maybe they are designed for hammer action tho'...?

I see you are in the USA..(dunno if you have added that or I was just being thick!)

I'm no so grumpy now!

if all else fails ..drill a series of holes and join 'em up with a jigsaw/pad saw..rasp etc.

Good luck

Del

Nice to see you have calmed down abit Del, I was just going to dig out the straight jacket when I saw your other post!

Could you not put some tubes in the mould before you do the fibre glassing thus eliminating the need to drill the holes or do you get the parts out of shop?

Due to design and construction techniques we are not able to use tubes in the this area during construction process.

Augur bit for wood boring should do it. Been around a long time Most are over 12 inches long. Cutting edge cuts a circle then scrapes the core out. Has a screw point for penetration control. They are inexpensive so try one.

Just a thought to place fiberglass tube in the places needed as the hulls being laid.

You might be able to accomplish the task with a 1 3/8 Forstner bit. You would then have to fill the void around whatever is being inserted into the hole. A good coating of resin should do the trick and also make the junction more like a weld. Make sure you place masking tape on the surface where the hole is being started to minimize edge chipping.

You need a miller bit, as used to bore large holes through steel castings and the like......go and talk to a company that makes large castings and machines them too....

The only need that I see is that the drill needs to be mounted and angled very securely and you must bore very, very slowly (start around 60 RPM or less first), probably best with a pilot hole and then drill from both sides....Bit temperature should be monitored and maybe spray a light oil in the hole from time to time. Stop immediately when you see oil vapour being generated....use water if the fiberglass does not like oil....its only for cooling...

Do not make the pilot hole too large, if you do, the bit will tend to try and go through too fast.

I do not see a problem.....its basically just a big drill bit, probably with a Morse taper, that you might have to machine off in a lathe to fit your drill machine......

Make up some test sections first to see how the bits react.

Diamond faced drill bits are expensive, but last forever......

Used to be that hole saws wouldn't cut all the way through a 2x4, but now they make them deep enough for that. For 2 1/2" I'd cut from one side then go and drill from the other side. The guiding bit would have gone all the way through. If not use a regular (whatever that is) drill bit to finish the guide hole all the way through. I've done this several times on my boat and other projects.

That will work for some of the holes but there are instances where there is not enough room on the inside to do this. I will however do some more research on the manufactuering process to see if it would be possible to cut the holes at an earlier step in the process.

Since this is for a recurring production operation it would probably be cost effective to invest in a diamond core drill for the job.

Use <Google.com> & <Dogpile.com> to look for information about drilling fiberglass and core drills and others for the job.

No fair Del, Del Gato (#5) ! that was my idea. I'll go any way.

A circular template. The template diameter should be smaller than your finish hole by the diameter of the 'punchout holes' you'll be drilling.

You'll want the circle of the template to represent the C/L circle of the hole pattern you are going to drill with say 1/2' carbide tipped drill bits.) Once you have a bolt circle drilled A jigsaw to 'punchout' the center.

Then a straight grinder with any large number of possible edge grinding tools to smooth/finish the interior of the 2.5" finished hole.

If 'breakout' or chipping is a concern on the backside of the .5" holes; use a plywood backer to drill in to, and, reduce the diameter of the C/L of the hole pattern so punch out holes are not likely to effect the finished area.

That's my 2 cents worth. If cost is an issue I bet its hard to beat.

On the other hand, if time is more important, by using a pilot bit you can drill with a hole saw from one side and then from the other to match using the centrally located pilot hole as a , well, pilot. I would still go a bit small and finish by hand if at all critical and use a backer board as reinforced f/g is so 'chippy'. Any large wholesaler could get one of these to you. (diamond, of course)

CR3

Nice..

The whole (hole..) cost /time issue is always a good one...the company I work for is only 8 people...sometimes if we are a bit quiet then having a lobour intensive but low cost job is ideal. But of course other times we are inundated with orders so we want quick as possible... cost not an issue...

This makes my designing task pretty much a no win!

I'm sorry but your circular template is a very labor intensive way to cut a clean round hole. Hole saw cutting from each side through a common pilot hole is the only way to go. He's building boats...has to be a big one with 2.5in of glass, might take 10 holes. They might if they are really busy be moving 1 boat a week through production. That means 10 holes a week. Likely they cut all 10 holes in one day. This is likely a million dollar boat. I think they can afford a $40 hole saw. After the holes are marked I would guess <5 minutes per hole including time to get coffee.

As I think more about this I am guessing but maybe he is building his first big boat in his back yard, so there would be more likely 6-8 holes to drill. If he was a newbie in a production environment, his production manager wouldn't be allowing him the freedom to question what has already been proven to be the way to cut holes in fiberglass.

yeah like I said. If you need to pop qty2, 2.5" holes you may not want to shell out $65USD for a hole saw. If contour or such is an issue the hole saw might not be the best either.

I am glad to see you agree with the 2nd part of my post though.

CR3

" Any suggestions?"

Whatever you do, do it safely. Full face air supply mask is best. Close fitting goggles to keep the dust/short glass fibers out of the eyes, and respiratory filter minimum.

Well said, we all forgot this very important area that should ALWAYS be mentioned.

As they are building boats, one would sincerely hope that they already knew this, but for anyone else, highly important!!

Have you tried Granger, Just a quick look in their catalogue found a 1 5/16" drill with 3 1/8" flute length and 1/2" shank. Or drill a pilot hole and cut half way from one side and half way from the other?

Well found, cutting these holes should be easy....

Your best bet is to have a diamond or carbide grit core drill made for your application. The forester or auger bits will dull very quickly in fiberglass. A custom core drill should only be about $100~$200, and will last several hundred to thousand holes.

I wonder how many holes a normal drill, if used slowly and carefully, would drill as I suspect that more than one a week will not be needed......

But for such a company, a diamond faced drill should be the best alternative and should give years of service if used slowly...

do people read prior response?

"do people read prior response?"

Have ye not read, It is written, Ye shall not read prior responses lest ye have nothing new to say!

....seldom......in my experience.

The drill idea is basically what I said some days ago, but what the hell!

Just use a core drill, available from any industrial supply co.

yes, the core drill with diamond mentioned above is your best bet. If you can punch a 1/4" thru hole pilot you will get a straiter hole.

You will want a 40-60 grit diamond. You'll have to drill fairly slowly 125-250 rpm's and I would use water for coolant as well as keeping the dust down. If you can get a setup that squirts the water directly in the inside of the cutter it will perform better for you.

Scooter

How about using a diamond tipped drill!

How about using a diamond tipped drill!

HOW ABOUT USING A DIAMOND TIPPED DRILL!

Porque no utiliza una broca con una punta de diamonte!

Oy why don't you try a drill with a diamond tip!

I even red the above posts!

There you go, no more excuses, I even did it in spanish!!

I was just about to do a drawing in 'paint' but that would just be stupid!

Or use a sharpened stick and a bow!

maybe even an old screwdriver and a penknife!

or get bugs bunny to chew them out!

no better still, get Taz on the job!

Enough, too much beer last night, Brain is scrambled, cant....go...on.......any..furt

only 2 problems with that:

1) diamond tipped cutters in 1"+ get very very expensive

2) diamond plated drills cost 1/3 the cost of diamond tipped and start at about $400.00 USD

diamond core drills are about $100, diamond hole saws are about $70. A little tooling and your offf and running

All this talk of diamonds.

When the wife finds out he is buying all this diamond bit stuff for his boat, sometimes known as the other woman, these diamond bits are going to end up costing a lot more than $70-400. Think thousands for that ring she always wanted. I suggest high grade steel for your bits for $40.

I suppose that all is needed to say really are things like;-

"Alls well that ends well."

"A stitch in time saves 9."

"A fool and his money are soon parted."

"A man with one eye is King in the land of the blind....."

I enjoyed the Blog, we just now need to know if our ideas have born fruit, well??? Or are there some very expensive hulls lying around still "Hole-less"?

Your Hole-ness (Your Holiness?) the Pope.....

Another possibility is to chain-drill in a circle with a much smaller size, and link the holes up with a padsaw or a jigsaw, finishing off with a rasp. A bit messy though the destination will be reached.

....this method has already been mentioned and even drawings displayed on this subject if you would care to read the Blog through......

Would it therefore be an awful bore to say that you should read the Blog first before posting?

Many others are also guilty.......not just in this blog either.......

Andy, haven't you read through the blog...you already posted a comment about reading the blog first so people don't repeat themselves

Ha!

It was to another of them that I replied. They each want their own personal message it would appear.........

I would like to thank everyone for their ideas, and let you know that I will be using the core drill when it is not possible to bore from both sides as was mentioned in one of the posts. We will also be lokking at ways to cut the holes in earlier steps of construction, thereby making them more accessable. Thanks again for all of your ideas.

May we ask as to what use this hole will be put?

A picture worth 8 words.

They are for drain holes in the transom just under were the outboard motor mounts.

Many thanks, now we know......

How big and what kind is the boat? That's a pretty hefty transom

31 foot Cobia.

Ok unless i somewhere overlooked it in the post here is my suggestion.

Most standard hole saws will cut to a depth of 1 1/4" so why not start your hole, Run a drill bit fully through at the center, and then approach it from the other direction.

Just a thought but I know space may be a consideration as well. Of course a right angle drill might work as well if it is.

Mr Double,

you would have saved yourself a whole lot of typing, if you had read through this complete Blog before answering. Not only is your answer there several times, but the reason why the hole can only be bored from one side too.....

The good point for you is that you are also probably too slow to catch a cold.......

Damn.

be happy.

in response to your sig:

...or burn their ass with it.

Are all germans so abraisive or did you just happen to be that way.

At any rate I prempted my statement with that and offered it up more in jest than anything else just to add the using of a right angle drill in case it might provide a little assistance.

Think about that you git whilst you make yourself another beer to swill in.

Why don't you put your brain & eyes properly in gear before losing your cool?

It was your failure, not mine.....

Maybe you will remember this the next time you log on better after being told?.......or maybe not......

True your failure is being a complete and total a__.

"It was your failure, not mine....."

Ladies and gentleman, I bring you .......MANAGEMENT !!

oooooh. aaaahhhh.

And Now for something completely different.

HAHAHAHAHAHAHAHAHA.

I would use a porta power unit and pull the inside cutting edge thru to the ouside cutting edge. It moves slow and you only dril the center hole.

Or the BI Metal hole saws. Northen tools sells them up to 3 1/2 in.

...another one who cannot read properly, only write!!

As stated above the answer is still the same.

That is a thick transom! what is it reinforced with? I know alot of boats which have a wooden beam going through the transom and was wondering, is it reinforced with wood or is it solid fibreglass or what?

The transome is made up of layers. The outer hull is approximatly 1/4 to 3/8 inches of fiberglass then a layer of what we call penzke board (not sure of the exact composition) it is a gray board about 2 inches thick then another 1/4 inch layer of fiberglass.

Forstner Bit http://www.wisegeek.com/what-is-a-forstner-bit.htm

Could you use your hole saw to the depth it goes then break out the middle section and start drilling again. I do this with timber but don't know if the fiberglass would break in the same way.

That is actually how the holes are being cut now. I was just looking for a more efficient method.

I'm way late on this string but if its a long term solution your looking for have you considered using a "slugger bit" .. Hogan makes them, for steel alum and such .. they can be sharpened do not require a pilot hole and create quite a nice whole. I will say it does require a rather solid drill. We use a magnetic based portable drill press(Mag drill) though that wont do for fglass I'm sure you could make a clamping plate in place of the magnet. Ive seen themas small as 12 inches tall bout 7 wide and 5 deep.

FRP, being abrasive and tends to load up your cutter is very hard on tooling,

We have used a rasping bit, (fits into CNC Router,) but snce I presume that this is done by hand, Can you try an adjustable fly cutter.