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[dodes]

You know Bob, many years ago, in my distant youth, I watched an old shipwright in Malden Essex, bore a hole with an old auger, through an 2" deep saddle chock through the deck of a barge and through a 8" square beam underneath and the hole went true for the securing bolt. So yes if you are careful in setup and watch how you go should work out okay, mind this old boy had been doing it long before I was born. But get some old scrap bits and have a practice run , shore you will be okay. Wish you all the best and happy building.
David

[dodes]

Hi Bob, meant 2foot thick block not 2inchs.

[ballastanksian]

If the drilling and fitting and tidying of these bulkheads goes to plan (and why shouldn't they?) then everything else should be a breeze albeit a large breeze  Here's to Thursday Bob 

[Bob K]

Thanks for all the feedback chaps.  This is a critical operation as Ian says, the build depends on me getting it right.
Hopefully the rest will be like building a model boat, but four times bigger than usual.

Thursday?  I was chatting to a colleague from our club about an upcoming event and I happened to mention my quandary.  It turns out he has a big pillar drill in his workshop and invited me to bring my stuff over after our usual sailing session on Thursday.  Serendipity.  Fingers crossed.

[carlmt]

Small suggestion - if it ends up that the holes do NOT line up as intended, why not open them up sufficiently to get the tubes through - and then plate either side of the bulkhead with the holes, in metal with holes of the correct diameter for the tubes.  The plates can then act as reinforcement for where the tubes pass through the bulkheads, screwed to the bulkheads, and the tubes glassed in to place.
Sorry - not very well explained methinks...........
Carl

[Bob K]

Oh dear !!   Today was not a success.  I took my stuff round to a colleagues workshop, where he has a very large pillar drill.  Setting the stack of bulkheads under the auger was OK, but even with very low rpm and very slight feed the auger's teeth kept biting in, jamming the large motor.  It was almost as if the screw thread on the central V was trying to pull the cutting faces into the wood. 

Thinking cap on again.  No point in trying a flat auger.  The whole point of this one was to bore out precision-cut holes that would be exactly vertical. Successively cutting one inch holes with a tubular cutter, removing each layer when cut, would not work either.  A hand operated bit and brace could not guarantee all three holes being exactly vertical and aligned.  They need to be machined to run true.

[ballastanksian]

I have had success using a Forstner bit for drilling several types of wood and board. As they have a longish shank, a Forstner should give you the depth required plus a bit.

I have found them to drill a hole a bit bigger than the diameter stated, so a 25mm bit might cut a 25.5 or a 26mm hole. I have one if you would like to try it out; I can post it to you to try?

[Capt Podge]

I am definitely not a wood-working expert but, in my view, I imagine your modern auger is designed for hi-speed cutting. That would account for it biting in and stopping at low speed.

If you could fix together some scrap bits of ply to the same thickness as your intended work piece, perhaps your colleague would allow you to have a go at a high speed and see if that would work - I'm assuming you didn't try this at the time - also, as a thought, would light machine oil give the auger any assistance ? might be worth a shot anyway.

Regards,

Ray.

[joppyuk1]

Oh dear !!   Today was not a success.  I took my stuff round to a colleagues workshop, where he has a very large pillar drill.  Setting the stack of bulkheads under the auger was OK, but even with very low rpm and very slight feed the auger's teeth kept biting in, jamming the large motor.  It was almost as if the screw thread on the central V was trying to pull the cutting faces into the wood. 

Thinking cap on again.  No point in trying a flat auger.  The whole point of this one was to bore out precision-cut holes that would be exactly vertical. Successively cutting one inch holes with a tubular cutter, removing each layer when cut, would not work either.  A hand operated bit and brace could not guarantee all three holes being exactly vertical and aligned.  They need to be machined to run true.

Concerning the hand brace alignment problem. Have you thought of constructing some sort of jig that would hold the brace in alignment while drilling? I have in mind something like the thing my dad had for his electric drill. It was much like a vertical pillar drill, you just screwed the normal drill into it. Have you tried enquiries on any of the woodworking forums for a solution? (e.g. Good Woodworking magazine).

[Bob K]

Ongoing R&D

Not much progress since my last missive, but some decisions made.  The way that auger snatched dramatically at just a touch of speed there is no way I would try it on much higher rpm.  It could prove dangerous. 

One key disadvantage when in someone else’s workshop is they naturally want to operate their machinery.  But it is my precious bulkheads.  I have resolved to buy my own pillar drill stand for my Bosch CSB 500.  Amazingly these are not in stock from places like B&Q, Wickes, or even Screwfix.  I really needed to see it before committing via a tiny thumbnail image.  However, no choice.  I finally settled on the Axminster DS2 drill stand.  Excellent make. Very solid.  Big heavy base, and a drill travel almost deep enough to go through the whole stack in one pass.  Although I may never use it again, it is essential that the holes are exactly vertical.  Ten professional local carpenters would not even reply to my messages.  I have to drill it myself. 

Taking a tip from Ian (ballastanksian) I had a look at Forstner drill bits.  Worth a try on some scrap pieces.  Looks more controllable.  I have ordered one.  Options are always good -  Thanks.

[dreadnought72]

Another option? Drill numerous smaller holes just within the target diameter with the pillar drill first. Then your industrial auger won't be choking up at slow speeds doing the whole cut itself.


I'd try that on scrap first.


Andy

[radiojoe]

Hi Bob just another suggestion how about a Holesaw, you can get a mandrill with an extended shank if necessary, then drill a bit clear the holesaw and drill a bit more, I think that's what I would use, just a thought. 


Joe

[tugboat Tom]

Why You try it with a milling machine.
Look if there is a woodworking shop in your town.
Succes,
Tom

[Colin Bishop]

I sympathise with Bob. Anyone can drill a hole but to drill a large accurate hole through several thick laminations is something else again.

Just a bit of lateral thinking but would it be feasible to drill oversize holes in the bulkheads and then make a series of of alloy plates which overlap the holes and which have accurate dimensioned holes drilled through them? (two plates per bulkhead with fixing holes on the outer edges) Then bring the two halves of the hull together with the bulkheads fixed in and line everything up. Pass the rods/tubes through the holes, slipping on the plates as you go and then when everything is in place screw or bolt each plate to its bulkhead. Everything should then marry up nicely and you have the option of using filler between the plates on each bulkhead to fill in the gap. Hope this makes sense. Basically it is an adjust and fix solution.

Colin

[ballastanksian]

Taking several ideas already suggested further and adding them together:

Drill the holes oversize and fit the bulkheads in the hull. But instead of having several small plates, make up the required number of larger plates from steel or 1/4inch ply with 25mm holes drilled at the points you want to form your tube group.

Then put the plates in the hull by the face of the bulkhead they are to fit to, then insert the  tubes into your plates and through the bulkheads and screw the plates in place once the tube group has been checked for being parralel to a chosen datum line both vertically and horizontally.

These lines may be unassociated with the hull but perhaps the top of your bench and say a length of batten clamped to the front edge that the hull is measured againts to assure it is straight. The plates can be clamped to the bulkheads and screwed in place once you are sure of the tube group being square.

Whatever the path you choose Bob, you are doing the right thing by not rushing it with potentialy disastrous results to the project, or worse still you 


 

[warspite]

I might be out of turn here but, a large board with all the bulkheads correctly lined up and clamped in place, using a pillar drill, drill 4 holes through the lot at strategic positions, the diameter of which is just big enough to take a dowel piece.
fit 4 dowels in the board and then individually drill the 3 tube holes through each piece, the dowels acting as holding points that are the same for every piece, on watertight bulkheads the dowel holes are plugged with dowel.

this idea stops the holes being too deep for a large drill, the pieces are individually drilled exactly the same whichever piece is attached to the board - essentially a jig.

[Colin Bishop]

The problem with drilling the hole as a one off is that you have to be sure of getting it 100% right first time. The alternative solutions with bigger holes and use of centering plates give you a degree of wriggle room and the opportunity to make adjustments to get everything lined up exactly. And it will all be concealed in the finished model.

Colin

[dodes]

I think Warspite gets the biscuit, best advice yet I believe.

[Bob K]

I really appreciate everyone's support and encouragement.  I am just being very cautious, knowing I have every opportunity to irrevocably mess up an operation on which the whole build depends.  I am no cabinet maker.

The pillar drill stand arrives Monday, the different drill bit Tuesday.
I will probably spend time thinking about things, and then practicing on scrap timber and ply, so don't expect instant news.  I am confident that my 8 bulkhead pieces are individually an accurate fit, and hopefully dowelled together in reasonable alignment.   All I need is the three tube bearing holes to run true through the whole stack.
There needs to be clearance, but too much clearance impedes the accuracy when I come to epoxy it all in.

[derekwarner]

  .... "I think Warspite gets the biscuit, best advice yet I believe"

Yes dodes, must agree......get that man a cup of tea too ..........

There may also be a few frames about midships that have an identical profile ....so the dowels would also ensure total accuracy of profile when edge surfaced together

Derek

[warspite]

The basic premise is that we all know that a small bore bit in a pillar drill will go through relatively straight successive diameters to the dowel size will be easier, through the whole 8 bulkheads will be relatively straight forward, then as each piece is plugged onto the dowels the larger hole is drilled, being a single bulkhead means less chance for the bit to snatch in a deep hole of various parts, once the first hole is cut through the 8 bulkheads, the set up is aligned with the next hole and the process then repeated for that hole.

I have a drill bit here that is designed similar to a wood bit, difference is that its diameter is adjustable, but unsure to what diameter, have never used it either as it cuts like a radar sweep, so a bit reluctant to use it, if I can find it I will photo it.

[Bob K]

Sorry guys, but there is no way I am going to cut bulkheads one at a time, or start with a small drill and open it up with successive sizes.  The alignment of the three centre lines needs to be super accurate.

In the mean time I am trying to work out a set of clamps to hold the stack down securely.  Some large threaded rod, big washers, nuts, a thick plate as the clamp and a measured thickness of timber on the outside.
The drill base is large enough to not worry about bowing distortion of overhangs.

[warspite]

super critical aligned holes does not translate as a viciously snatching big drill bit, with the bit wandering and creating egg shaped holes is some cases, but I might be wrong and personally err on caution.

[Bob K]

How do I say this nicely ?  I know you are trying to help.

Watching someone else trying, and failing, to drill my stack of carefully shaped bulkheads that have taken two weeks to make was a bit fraught.  One thing I learned was that I needed to drill them myself, first gaining practice on scrap timber.  My Axmintster DS2 pillar drill stand is due to arrive today.  By Tuesday I will have a choice of two different choices of auger bit types. 

The most important aspect is that the dowelled stack needs to be drilled through accurately as a single assembly as the alignment is super critical.  Using a pillar drill, once the first bulkhead cuts the subsequent ones will follow exactly.  The cutter is not going to oscillate or bend.
Cutting them one at a time does not help the motor stalling problem, and will only introduce more positional variables, as would using successively larger drills. 

Patience is required.

[warspite]

I understand - I was not be critical - just that I know you are being very careful, and believe that a couple of dowel holes can be drilled vertically more accurately than the large diameter bit, as a jig and the lesser thickness to drill through would be more accurate than the stack due to deflection of the bit, unless of course the progress through the stack is so slow that you end up burning the walls of the hole due to friction. Hope you get there and progress further on.