Thread: Plaining wide surface issue

What you are seeing is the same as my experience with harder woods.

I found that using a Makita 4" belt sander with 60 then 80 then 120 belts, and then going to 180 and upwards with an ROS removed the banding.

It also may help if you take less than 1mm on the final pass.

BTW going from 40 to 120 is too much of a step.
I try not to go more than double the grit of the previous paper in any one step but it will be better if the step is only 1/2 of the previous grit.
It sounds like more work but its actually less work and uses less paper.

its quite common for lines to be left after router planing a board. It even happened when using a cnc router which is dead square and rigid. mostly its because if you take a full router bit diameter pass each time, half of the cut is conventional cut, and the other half has been climb cut, pulling half of the fibers forwards and the other half backwards.

here is a pic of a redgum burl I had planed down using a router, i wasnt very fussy with the setup or the movements back n forth, i just ploughed on through it. you can clearly see the the difference between the conventional and climb cut, but the surface is very flat.
20150205_143909.jpg
I would be sanding more with the 40grit ROS until the lines have been removed or are very faint, and then i would move up to 60grit, 80grit, 120grit, 180grit all using the ROS.

Thanks BobL & Kuffy - much appreciated.

I will go back & do a bit more with the 40 & take your advice re less steps with the next grit level.

Is there any advantage routing along the grain rather than across ?

UPO- Richard

I have surfaced a few slabs using this this method.
1mm or even more is fine for initial roughing cuts to eliminate the high spots dow to the lowest point of your slab. Final passes at 0.5mm or even less is ideal and using a decent overlap of the cuts and will save you significant time in sanding.You might need to shim your router on one side if you are getting a significant line on one edge from the cutter.It may even be beneficial to have a slight radius on the very edge of the planing bit rather than a sharp point.

Starting sanding with ROS at 40 grit seems rather extreme and an indication you are probably not getting a good enough finish fro the routing stage.In my opinion you should be able to get away with 80 grit to start, swirl marks at this level or coarser can take some considerable sanding out.

router planing is often used for big panels. a table top for example, say 2000x900. to plane with the grain you need to build a sled that spans 2000mm long, easier to go 900. you can also pick splinters out of the surface when routing with the grain, just like it happens when running bullnose or bevel edges around panels, the end grain rarely has any issues, but the long grain can splinter out for a mile.

As previously mentioned a belt sander is a fairly rapid but rough levelling/flattening tool.

Personally I struggle sometimes myself to get things perfect: doing hardwood floors with those big commercial hire jobs is particularly difficult. Even with my own 3" sanders I struggle with smaller jobs. It's not just about keeping the pressure even and constant motion over the work surface: if you sand from one side to the other (or end to end), then the ends get only one swipe each whilst everything between has 2. Theoretically you're supposed to sand the 2 diagonals first, then finish along or with the grain. I still struggle!

Some sanders have parallelogram sanding frame attachments specifically designed for "gentler" flattening, limiting the exposure of abrasive below the frame's brushed lower. The Holz-Her, Metabo BS1075, Wurth 75E, Atlas Copco, Wolf and Festool clones all fit the same frame which is currently only available from Festool after they purchased the rights to manufacture Holz Her's original design.

I achieve better (and almost as rapid) results with my Fess-tool Rotex 150E sander in rotary mode. Maybe 40g rubin may be a bit too coarse to start, but it sure is rapidly abrasive! I always find my fingertips held flat have a good feel for evenness or otherwise. A sequence of papers 40-60-80-120-240-400G (the first 3 in rotary mode, the latter 3 in random) gives a lovely silken finish. A hard pad will help with evenness, and minimise any edge "rounding". 2 hands & even, gentle pressure also helps. So does backing off the vac suction a tad.