Thread: Biscuit joiner, router, dado, spindle, other?

Hard to guess without any details of the size of the spline groove you want. Personally, I think that you want something more than a simple spline to allow for expansion and contraction, as you will be leaving the spline and the board edges exposed to weathering and water absorbtion. Would consider something like shiplap to be more appropriate, long lasting and weather proof, but at the expense of reduced board coverage. Could be produced with a router and rebate bit in a router table.

Of the tool options I think you could forget the circular saw and dado blade idea, as circ saw sindles are generally not long enough to accomodate a dado set. Likewise a biscuit jointer is not appropriate for making continuous slots accurately, and matching the slot width to ply thickness could be a problem.

Depending on slot thickness, a table mounted router and slot cutter set would cope well for running with the boards face down on the table, as would a spindle moulder with appropriate tooling. For wider slots I would tend toward spiral bits with router in router table and timber running face to fence, or alternatively a dado set in a table saw with the timber face to fence.

I agree with malb.
Shiplap would be easier to install and maybe cheaper (you don't need to buy the spline, although there'd be a little less coverag from your boards) than a spline.
If you do go with the spline make sure the ply is up to being exposed to the elements.

With the boards contracting in dry times there would be times that it'd be exposed. Similarly, when they expand with humidity the butt jointed boards might have nowhere to go (I've seen floorboards tightly installed in dry conditions pop up when humidity hits).

Thanks guys. I had considered ship lap earlier but have been dissapointed with both looks & how well it sealed. I guess I did not like the large gap that I have seen on the ship lap weather boards here, but that could be reduced. I am not sure how to seal the joint better (insect & rodent access), it is easier using the spline joint. I am batten screwing the boards the the frame. I am open to suggestions.

I guess with ship lap it could be an option to run the boards horizontally instead of vertical??

What tool would you use for ship lap?

Thanks again,
Shane

Originally Posted by permieshane

I am getting ready to clad the outside of our new home with 6x1 blackbut. It is well seasoned (20 months) & I will run through my thicknesser first.

I am going to run the boards vertically & would like to cut a full length groove in the side of each board so that I can insert a narrow length of ply as my tongue to join the boards. I will leave sufficient room in the joints to take care of expansion.

What is your opinion on the best tool for the job considering that I will not do much of this sort of work after this job is finished? Overwork a biscuit joiner or router? Make up a jig for my hand held circular saw & use a dado blade? Setup my spindle molder with a tungsten cutter head (only have hss cutters atm)? Or maybe someone has a better idea?

Shane

Hi Shane, for me it's a no brainer, you have a spindle molder
get a set of matching tongue and groove cutters and cut a tongue on one side of your boards and a groove on the other
the cover per board wont be the same as using a spline, but you wont have to deal with different wood types.
Also, you should add a detail to each joint to partially conceal the visual component of seasonal movement (I can't remember what this detail is called but it's a common treatment)

Originally Posted by permieshane

Thanks guys. I had considered ship lap earlier but have been dissapointed with both looks & how well it sealed. I guess I did not like the large gap that I have seen on the ship lap weather boards here, but that could be reduced. I am not sure how to seal the joint better (insect & rodent access), it is easier using the spline joint. I am batten screwing the boards the the frame. I am open to suggestions.

I guess with ship lap it could be an option to run the boards horizontally instead of vertical??

What tool would you use for ship lap?

Thanks again,
Shane

1. The gap that you need to allow for seasonal movement would be the same for splined or shiplap use, or tongue and groove for that matter. It is a function of the width of the boards and the degree of movement expected in the species under the range of conditions it will be exposed to.

2. If you are going to batten screw the boards vertically to the frame, you have a horizontal frame or horizontal battens on the frame? You are quite content to fix the boards with a single column of fasteners per board (double column fastening would control cupping better but inhibit movement between the fasteners).

3. Under no circumstances would I run basic shiplap boards horizontally outside as there is no way to drain moisture that gets pushed into the gaps in a storm, it will sit there and induce either exagerated movement or rot. Weatherboard is designed to provide an runoff mechanism and cope with movement. Alternatively, you could add an exagerated cove moulding to remove the upper exposed edge of the board to provide better drainage capability, at the expense of extra machining and an exagerated visible joint pressence

For tooling, as I suggested in my first post, a rebate bit in a router (preferably table mounted) or something similar in a spindle moulder would be suitable.

Just my thoughts

Thanks for everyone's input. After some serious consideration I have decided to go with board & batten vertically. I will thickness the boards first, batten screw the 6 inch boards with 2 screws, small gap between the boards will be covered with a 1 1/2 or 2 inch batten that will be batten screwed through the gap.

Shane

If you go board and batten make sure you prime all faces of the batten (you should prime all faces of the boards too) and seal each side of the batten with a good sealer like sikaflex once installed. You are just asking for rot problems otherwise unless the wood is treated.
screws need clearance space in the gap too...
Cheers
Michael