Why they're called Drifts

[Harry Miller]

http://www.imagestation.com/picture/sraid199/p8c58db0bf5eb2ad7747711390a0ad41c/f09e8045.jpg

As you can see this was not the first blow out. I was actually 0 for 6.

I didn't like the dark middle plank of this little transom so I'm using it for practice. But I think I need some advice as well.

I had my wife to help line it up but the quarter inch bellhanger bit always seemed to bend off to the left.

Thanks for any ideas.

[Donn]

Is the bit actually bending, or just not traveling straight?

[Gary E]

Because they dont know how to spell TIE ROD

Drift's...drift around and are used to line up several bores, hense the name "drift"

But whut do I know...these guys also call a part of a boat "deadwood"... aint it ALL dead if it's not still a growing treee?

[Seth Wood]

You should at the very least have a (clamped) straightedge to sight down. Drill slow and line it up correctly to start.

That said, it's a pretty narrow thickness you're drilling through; it might be worth the time building a jig to hold things straight and steady.

And also, practice, practice, practice.

For what it's worth, I've used barefoot ship's augers for larger holes, but I've never needed to drill a long hole this small.

[Dan McCosh]

Actually, I don't see why any transom would need drift pins to begin with. I fixed a lot of old stuff that used drifts on coamings, etc., after they split or rotted, and managed to eliminate them altogether.

[Tristan]

Are you drilling with no guides? I'd use two guides for the drill, one fixed at near the entry, one further out. I did this while drilling a shaft log in my Bawley cutter. Clamped one guide to the concrete clothes line pole, the other to the transom. Drilled through with a 1" waterpipe, with teeth notched and set in and out on the cutting end. Amazing, the pipe exited the keelson exactly where it was supposed to.

[Harry Miller]

http://www.imagestation.com/picture/sraid199/p7a336146441d681bc176642a47e60bff/f09e59d8.jpg

Thanks for the quick replies.
As seen in the picture the hole isn't straight.
When I filpped the transom and drilled from the other side it still bent to the left. And BTW my wife thinks she is the only guide I will ever need.
Having said all that I may just trust to Steve Smith's "all wood glue" for these white oak transoms.

[Donn]

Is there a reason why you can't install shorter drifts as you build up the transom? If not, you could set up a 'fence' of sorts, similar to the depth guage on a rotary hammer, but offset to each side of the bit, to the thickness of the planks.

[Dave Fleming]

First off, a Bellhangers bit is the wrong kind to use especially one of that small a diameter.

Best to do it in ( 2 ) steps.
1. using a regular length BRAD Point bit drill initial hole.
2. continue with another bit preferably a Brad Point of longer length

OR if you have a decent grinding wheel setup you can shape a Jobbers type drill bit to a semi brad point configuration.

A Doweling jig is a mighty handy thing to have in situations like this.

http://images.ibsys.com/2003/0506/2184258.jpg

Or this...

http://www.suiteronline.com/woodworking/images/plantStands/plantStandsLG-03.jpg

[Peter Malcolm Jardine]

I know I would probably jig that transom up in my drill press, but I appreciate the fact that you may not have one.

How about clamping the drill at the appropriate height horizontal to a flat working surface, and jigging up the transom to be the part that moves? Some wood blocking and fencing to control the transom would be in order.

The dowel block makes sense tho. You could make one out of wood with a steel insert.

[ 01-11-2006, 05:25 PM: Message edited by: Peter Malcolm Jardine ]

[George Roberts]

I drill 7/16" dia x 7" deep holes in end grain 7/8" boards will no noticable drift. (These are for bed bolts.)

Build up a 4 piece guide from hardwood flat stock - center piece is 2 pieces as thick as the drill diameter; other 2 pieces are the same thickness stacked with the center pieces are as thick as the work piece.

Stack and clamp the 4 pieces tight to a workbench top. The center pieces should be tight around the drill bit. Clamp the workpiece in position. Drill away. Clear chips on a regular basis.

I use 18" or 24" drill bits from Harbor Freight. My guide pieces provide 9" to 12" of guide.

[Bob Smalser]

http://pic3.picturetrail.com/VOL12/1104763/6583947/84760753.jpg

I use bellhanger bits quite successfully.

First, the dowel jig is a must. As is a drill of sufficient power.

Second, drill in increments no longer than a third of the length of the flutes of the bit, putting little pressure on the drill, and sighting simultaneously down the drill and the side of the board. Low pressure means the bit won't bend. Frequent pullouts and cleanings mean the chips won't clog and force the bit off. And if you sight carefully, you can see the drill bit shaft begin to tilt before you wander off too far to pull out and correct.

[ 01-11-2006, 07:38 PM: Message edited by: Bob Smalser ]

[Bob Smalser]

Originally posted by Dan McCosh:
Actually, I don't see why any transom would need drift pins to begin with.Because if the transom or rudder cracks, or a glue joint breaks, you still have structure to get home on.

Before modern glues, drifts were the only structure, as white lead, not glue, was used between the boards.

I don't believe it a safe practice to omit them.

[ 01-11-2006, 07:47 PM: Message edited by: Bob Smalser ]

[Bob Cleek]

I'll ditto what Fleming and Smasler just said and add that it really helps to drill those long bores FROM BOTH SIDES when possible, even if you have to plug both ends. First, mark your line on the face of the piece, then go a little bit more than half the way from one end, and then start out from the other. Your holes should meet if you follow your guide lines in each direction. If you want, you can also drill from the two directions with a bit slightly smaller and then bore the whole shebang with the size you want, thereby (hopefully) curing any slight error where the holes meet. I know this sounds strange, but I bet you'd have found success with a few of those attempts if you tried it this way. And, go slow and remove the chips as you go.

[ 01-11-2006, 08:23 PM: Message edited by: Bob Cleek ]

[chergui]

Harry and I are building the same boat. I'll be gluing up my transom soon (if I can ever joint the edges accurately). On the topic of glue, what glue would you recommend for a transom? I don't want to use epoxy. Gorilla glue looks good but requires a minimum moisture content and I don't have a moisture meter.

With regards to drifts, do you put the drift all the way through the transom from the outside edge or do you put short drifts vertically between each laminated panel so there are no holes exposed to water. I'm afraid to add drifts, the H. mahog is not something I want to practice on. Probably wasn't a good choice for my first boat.

[Jay Greer]

I use a "Preacher" and a bare foot auger in a brace.
The Preacher doesn't lie, old East Coast folk saying.
And the bare foot auger won't drift askew.
JG

[Wiley Baggins]

Originally posted by Gary E:
Because they dont know how to spell TIE ROD...Harry,

I'm with Gary E on this one. However, I haven't had to do the work with wider boards having used more laminations for a rudder. Obviously no worries though, as the usual suspects seem to have come up with good solutions to the problem. By the way, that's not for what I think it's for...is it? ;)

[Dan McCosh]

Not to hijack the thread, but for a transom, interior cleats seem a better solution--or a double-planked laminate. Maybe this boat has the interior of the transom exposed, which probably is why drifts are used.
A rudder is a different proposition, but having witnessed a rudder failure when the construction relied on drift pins as an attachment, I don't trust them in that use--external strapping is far better. The replacements I've done for assemblies formerly relying on drift pins generally have been some kind of lamination.

[pipefitter]

Why not just drill each piece individually with the face lines as the angle guide?Make up the slab of narrower pieces and then cut the shape after, incase the holes are slightly off? I also don't see why they have to go all the way through.Seems that the pin in the center of the board would do nothing.If it needs all that then it must be seriously underbuilt.Also,could start out with thicker stock,see where the pins come out and then surface it accordingly?

Chergui,I think mahogany was an excellent choice for your first boat. It drills straighter,works with hand tools easier and is just all around one of the best choices in hardwood. I had a much nicer experience working with the mahogany over DF.The time spent bringing the lesser wood to finish, offset the cost difference.

[ 01-12-2006, 11:49 AM: Message edited by: pipefitter ]

[FSS172]

Anyone have any thoughts about splined joints. I've used them to glue up the transoms of several small boats and they've worked fine despite neglect, abuse, and all the usual real-world stuff. Just asking because no one's mentioned it...

[Bob Smalser]

http://pic3.picturetrail.com/VOL12/1104763/6490387/81088736.jpg

You can spline the joints between the boards....you can dowel them with bronze pins like above....you can T&G them....or you can glue the edges without reinforcement. None are any stronger than the other if not needed for alignment, although some manner of joint reinforcement aids the structure should a glue joint fail.

http://pic3.picturetrail.com/VOL12/1104763/6583947/84781037.jpg

What full-length or overlapping drifts do, regardless of how the boards are jointed, is effectively reinforce the entire span of the structure while allowing the wood to expand and contract seasonally, as drifts aren't glued in. Cleats or straps screwed or riveted across a large crossgrain span can impede seasonal movement sufficiently to crack the wood.

[ 01-12-2006, 03:07 PM: Message edited by: Bob Smalser ]

[DanO]

Just adding my 2 cents worth. Drifting this way was not difficult at all. No errors, even the first time. Wish I could say that about the rest of my project!

http://www.imagestation.com/picture/sraid104/pf9fe1d33fc7b59f85fbd7a959d832e23/f98899e3.jpg

This is a home-made jig:

http://www.imagestation.com/picture/sraid104/p38074b79b9bbf0ef36408dc55968ac10/f9889972.jpg

The completed transom:

http://www.imagestation.com/picture/sraid153/p0982095d6b6f2581a50687d3b8eddc19/f58cd981.jpg
Dan

[ 01-12-2006, 09:56 PM: Message edited by: DanO ]

[pipefitter]

Nice work.Nice simple jig too.

[ 01-12-2006, 11:40 PM: Message edited by: pipefitter ]

[GregH]

I know this is going rile up all you purists, but I have to ask- "What's all the fuss about?"
Specifically, what is the purpose of "drifts' anyway?- alignment? reinforcement- reinforce what?
For thousands of years, boats have been held together Mechanically- (fasteners)- dowels, trunnals(sp?), wedges, bolts, screws etc. All sorts of ingeneous MECHANICAL devices. Why? Because strong, reliable glues did not exist. Even the wonderful Christ Craft boats through the 1940's were all screwed together- no glues. Fortunately, science has prevailed and provided us some amazing sticky stuff. Along with a couple of boats- (working on the third), I've built and flown two all-wood structured airplanes - both completely relied on glue alone to hold them together. Unless one's interest is purely historical authenticity, or self-frustration why would one not take advantage of new technology? Come on guys, isn't this... "much ado about nothing"? Let the ranting begin.

Greg

[Dan McCosh]

I've delved pretty deeply into the area of composite construction, adhesives, etc. in other fields, including at least a superficial study of the B2 bomber. It's impossible to generalize, but most people working with these kinds of polymers are deeply suspicious of mixing old and new technologies--some even suspicious of the predictability of an epoxy glue joint. Mechanical fastening's main benefit is its predictability, and the ability to inspect the joint. That said, I've done major and minor repairs; cobbled up new structures; repaired masts; epoxied cedar decks, using many synthetics. Many of these projects didn't fit a neat theory about expansion, glue vs. mechanical, etc., but the deficits of the systems involved weren't critical--at least unlikely to cause catastrophic failure. Most traditional techniques aren't truly understood--they just work in a predictable way. It's also enjoyable to figure out how to do this stuff.

[Seth Wood]

Bob, to follow your point above about external strapping, Larry Pardey recommends that method for building rudders. His straps were rabbeted in flush, I believe. I don't remember if he also used drifts or pins. In his case the straps were mainly to prevent the wood from warping.

[Bob Smalser]

Originally posted by Seth Wood:
Bob, to follow your point above about external strapping, Larry Pardey recommends that method for building rudders. His straps were rabbeted in flush, I believe. I don't remember if he also used drifts or pins. In his case the straps were mainly to prevent the wood from warping.We're not talking modern polymers here, we're talking solid wood.

1) No bronze strap is gonna prevent wood from warping if it wants to warp.

2) Impeding seasonal movement across any crossgrain expanse larger than around 12" without considering species, grain, and the moisture extremes the boat will experience in its lifetime, is a complete crap shoot.

What worked in mild, humid Honduras can easily be a disaster where you live, but q-sawn H. Mahog can cover a lot of sins. This end of it is more science than art....get out the book and run the numbers.

[ 01-13-2006, 10:54 AM: Message edited by: Bob Smalser ]

[chergui]

Bob, where did you get your bronze pins. Did you make them yourself? I'm going to get some scrap bronze and was thinking of having a machinist make them for me. I don't know anything about metalworking. The drifts will help my alignment problem with the one slightly cupped board.

Another question, could you make dowels and use those instead of bronze? Would they work as well?

Jon

[Dave Fleming]

Drifts are made simply out of the appropriate material, ie: Bronze, Galv Steel, Monel etc...

So few woods have the same properties as a good metal drift that it would be, IMOP, a waste of time and material.

Besides they wouldn't have the same holding power as a proper 'nicked' undersize drift.

[Bob Smalser]

Silicon bronze rod to fabricate drifts and pins in several diameters and lengths is available at Alaska Copper in Seattle and McMaster Carr in Atlanta, among others.

[shamus]

I find myself agreeing with Greg H. If the glue is going to suddenly fail in a transom and sink you, then there are a whole lot of glued lap ply boat owners who presumably shouldn't set sail at all!

[chergui]

Thanks Bob. They have an office right here in coquitlam also. I'll pick some up.

On a 3/4" transom, would a 1/4" drift, leaving a 1/4" of wood on each side be alright? Are there any guidelines for this? Is the drift supposed to be a bit loose or fit snugly in say a hole drilled the same diameter as the the drift? I'm wondering if a tight fitting drift would actually make things worse and split the wood (if it changes shape) with just 1/4" of wood to play with on the sides.

[Tom Robb]

GregH,
It may be reasonabe to hope that your glued wood airplanes don't go through periodic soaking in water.
The aircraft parts I've seen (eg.,wing ribs) are way daintier than any solid wood transom. Would that make the cases sufficiently different such that aircraft practice might not apply here?

[fixmyboat]

anybody have a source for barefoot ships augers?