The first problem was to get the huge slab of wood down to a more maneagable size... Like Id said, I was initially torn between two possible table formats and I needed to make a decission so that I could make the cuts in the right places... Well, I decided to go with the long thin rectangle styled table over the elyptical option since it keeps the slab of wood more intact and after all, thats what I really like about it... the size and thickness of the single piece of wood.
Having decided that, I set about trimming off the edges (they were very rough and had insect holes etc... I really couldnt have used them on the final table even though its nice to preserve the "live edges" of the original tree trunk). The slab was still over 3metres long though, so I also decided to make it just 2.4m long so I also lopped off 60cm of the narrow end (Ill use that for a bed-side table that ill make later I think).
Right, the slab of wood is now becoming much more manegable :)
But I cant work on it where it currently is (tucked up next to the house under the back deck), so I get some help from a neighbour and the two of us move it without too much struggle around to the front of the house.
I put it on work horses here and have a look at that "crowning" problem that is then next "issue" to be addressed...
Hmm, well its still there :) See the curvature of the wood in the picture below - looking across the end edge of the slab.
Right, so Ive figured out how Im going to try to deal with that.
I get two big flat and straight planks of pine and I attach them to the sides of the saw horses as "rails" for my "contraption". These are going to be my references for making the table top "flat", so I spend a while making sure they are parallel to each other and that they are solidly attached to the horses at the right height.
But the big slab of wood also has a bit of an "arche" too it along its length... This is much more slight than the crowning, and while I could just machine the table top to be exactly flat, I decide that the little bit of arch is a good thing as it will resist gravitys tendency to make the table sag over time with a long unsupported span of over 2 metres... So instead, I decide to make my two side rails have the same arch by using a very coarse grit belt on my sander and spending about 10 minutes on shaping each of them to match :)
OK, now to make the "contraption"...
Which is just a carriage for my router so that I can run it over the whole surface of the table with a repeatable and solid height setting. Im more or less building a very large milling machine :))
The side rails (longitudinal rails) are bolted to the saw horses. And a friend let me have the use of an old exercise treadmill frame that he had (its a very solid rectangular aluminum frame) and Im gonna use that as the "latteral rails"... essentially, Ill rest this aluminium frame across the side rails and slide it along the table top to whatever place I want it.
Now, I have to build a carriage for my router to run on the aluminium frame rails...
I looked at a bunch of roller and wheel options for this but I ended up deciding to use a couple of simple old "clothes line runners" as the wheels for the carriage...
They come as a pair of about the right size; They are pulley wheels that will run nicely on the edges of the aluminium frame (rather than wheels that need a track). They are solid and well centred (so there is no flex in them and thus variability in the hight of the router)... and finally, they are as cheap as dirt :)))
So then I spent an hour or two cutting up a 2x4 and screwing it together around my router to make the carriage...
And this is what "the contraption" looked like...
... You cant see much I guess, but I ended up with a router carriage that was very solidly tracking (not more than about a milimetre of lateral movement) and had virtually no vertical "slop" but was still acurately height adjustable with the routers built in height adjustment system :)))
So, I layed it over the table and moved it around to see what sort of cut depths I was dealing with....
Hmmm quite a lot !!
It looks like im gonna need to take off about 15mm of wood in some places... Thats a lot and more than the router can do in a single pass, so Im gonna do two rough cuts to get the bulk of the material off and then one more finer finishing cut... This is gonna be a lot of work because I can only take "swipes" of 10-15mm width with the router bit (channel cutting bit of about 25mm diameter). and after each swipe, I need to physically slide the whole router,carriage, and aluminium fram along the side rales by 15mm before I take another swipe...
Oh, and I have to be carefull too, cos this isnt a professional milling machine... If I move too fast or carelessly, the router carriage could jump off its rails and then the router would dig a lovely big and un-hidable hole in the top of that very expensive lump of wood... we definitely dont want that, so I need to pay attention and go slow (The "pay attention" part is no problem, but the go slow is definitely a challenge for me!)
Oh well, just have to get started...
... push, pull,slide, push, pull, slide ... repeat about a thousand times: and all with the wood chips flying and the whine of the high speed router... great way to spend a day :)))
... And about five hours later, after spending the whole day in the sun working on "the beast", this is what I had...
Yep, it is now "Flat"... but its still, far from "smooth"... I figure Ive got about the same amount of time again to spend sanding it down to make the surface good for coating.
I spent another hour and a half with the belt sander using 50 grit to get the router lines out of the surface... next is 80 grit, then 140 grit... etc, etc...
But look at the beautiful grain :))) ... its really gonna be nice when its done I think :)
Im gonna keep at it when I can after work in the evenings, but time is rappidly running out.
The leaves here in Vancouver are starting to change colour, and the sun is now set by 8pm. Im definitely not going to get this project done before the rains come, so Ill just try to get the top smooth and flat and maybe a "sealing, coat of finish so that I can bring it inside the house for the winter...
Work in progress... Ill keep you posted.
