PDA

View Full Version : Splining saw blade



RFNK
19th January 2009, 08:22 PM
The Twister I'm soon to commence restoration of has a splined hull. I'll be redoing the splining and splining where new planking will be fitted. I'm going to need a a splining blade to fit a small circular saw to do this. Anyone know where a splining saw blade can be obtained? Rick

Darce
19th January 2009, 10:57 PM
You could try these (http://www.leucoaust.com.au/) guys, or these (http://www.chapmansaws.com.au/) perhaps. I did find an old post in the woodenboat forums recommending carbide (http://www.carbide.com/) but they're in the States.

It looks like the scoring blades for panel saws might do at a pinch, they can come in a conical kerf, dunno if they'd form a sufficient wedge though you may be able to specify an angle on the wedge (10° ?)

I'm assuming you want to cut a wedged spline rather than square.

RFNK
19th January 2009, 11:09 PM
Thanks Darce. Yep, wedged splines with the wedged cavity narrower at the inside end than the spline for a tight fit. I hadn't thought of actually having the saw blade made. I actually feel pretty stupid that I didn't think of that! The sites you've sent look perfect for this! :2tsup: Rick

Darce
19th January 2009, 11:21 PM
Finding quite a lot of negative responses to splining though. The general gist seems that you'd only spline if there are large gaps or you risk squeezing out the hull.

Dunno mate, might want to research it first - as if you wouldn't anyhow :wink:

http://i470.photobucket.com/albums/rr69/rfnk/Windrosehull1.jpg

These should take up again once wet wouldn't they?

RFNK
20th January 2009, 12:07 AM
I think those open seams would close again too (they're pretty fine cracks really to have after 5 months out of the water) but the hull's already splined so if I removed the splining the gaps would be quite large. Some of the existing splining will have to be removed - I'm not sure how much yet. It's likely that the easiest way to do this will be to cut new grooves just slightly larger than the existing ones. I'll fasten a batten along each seam where the splining is shot and then run a small saw with splining blade along the seam. In most cases this will remove the old spline and just a little of the sides of the grooves, so the new splines will be bedded into fresh surfaces. Having said all that, I don't yet know if the whole hull is splined (I suspect it is) and how much really needs to be replaced. Certainly there are some planks that will need to be replaced so there'll need to be new splining for them, at least. I also don't know if the original builder glued the splines in or not, yet.

The guy who built this boat also built our Folkboat. The Folkboat was built in 1962 and he went away from convention when he built it. It's built from coachwood plywood and each plank is glued with resorcinol. While various parts of the boat needed restoration when we took her on a few years ago, the hull was and remains pretty close to perfect - no rot, no open seams (even after nearly 3 years out of the water) and as tight as can be. This builder really knew what he was doing so I'll be guided a lot by what's already there. The faults I know exist in the boat are tired fastenings and cracked frames in the tight turn of the bilge aft (a problem I've seen to be pretty typical of these sorts of boats with steam bent frames) and problems associated with neglect or poor modifications done long after the builder was off the scene (e.g., running thousands of screws through the deck sheathing to secure thin, teak decking). So, there'll be some new splining but I don't know how much yet.

There's also quite a bit of gribble worm damage around some fastenings and seams (through neglect). All in all, it's even possible that we'll need to sheath this hull to strengthen it and protect it in the long term. I know that sheathing goes down like a lead balloon within the WB fraternity generally, and I'm not over keen on doing it but, if we really do need to do it, then splining will be essential. Rick
Rick

PAR
20th January 2009, 07:14 AM
Spines or what I call wedged seams (a more accurate description) work fairly well as a repair on moored craft or dry sailed boats, but they like most things have draw backs. The wedge (spine) ideally should be of the same species as the planking so their expansion qualities are the same.

I've installed wedges before and I've had to make by own blades. I set up a grinding stone at the angle I wanted and did every other tooth, then switched. You'll have to re-cut the face of each tooth as well. You'll grind about 40% off each carbide tip when done.

Make the wedges deeper then necessary, so you can pound them in, then plane the excess flush with the hull when the glue cures.

The problems with wedges are: They don't take to wet/dry cycling very well and will spit out the wedges. Since you're gluing the plank edges together, you run the potential of damaging the plank edges with excessive movement (loose fasteners, broken frames, etc.), which makes repair more difficult. The hull becomes a homogonous planking structure with this method, so point loading and stress risers can become an issue if it wasn't previously. Repairing wedged seams is more difficult then caulked seams.

In it's favor: Wedge seams will produce a smoother hull, without the slight hollow or proud seam line common with caulked boats. It makes the planking stronger and if well fastened the boat stronger. It lasts longer then caulked seams. It tolerates dry sailing much better then caulked seams. It's not prone to sudden failure like caulk, where a seam just springs leak out of the clear blue.

You could 'glass the bottom of this style of seam with better results then caulked seams, though it's generally not advisable with this type of construction, particularly from a re-sale point of view.

Judging from the photos, the wedges look to be glued. The 4mm gaps are about what you'd expect if you wedged a caulked boat.

RFNK
20th January 2009, 08:01 AM
Thanks again PAR! I'll take the paint off a shady part of the boat soon and just check if if the whole boat is already splined, and also see if we can work out what the planks are made from. I'd only use the same species for splining.

I'm not worried about resale, I'm what we call in Australia a bower bird - I never sell anything. The bower bird is a bird that lives in Oz and Papua New Guinea. It collects pretty things (flowers. leaves, bits of coloured plastic, aluminium foil etc.) and leaves them lying around its `house' (bower/love nest). This boat was given to me. One day I'll probably give it to someone else but, hopefully, that'll be after many years of great sailing. Rick