An Evening in the Shop #2: Flattening Boards

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Blog entry by ChunkyC posted 09-25-2011 12:15 AM 1977 reads 3 times favorited 5 comments Add to Favorites Watch
« Part 1: Homemade Knobs and Handles Part 2 of An Evening in the Shop series Part 3: Flattening Boards part II »

I’ve planned on not getting any “productive” work done in the shop this weekend. Instead, I’ve planned on working on techniques. I’m the type of person who like to have a couple different ways of doing things in my tool belt. So to that end, I’ve been playing around with flattening boards.

A jointer would be the easiest, if I had one. I don’t have any room left in the shop for a jointer, or at least in it’s current configuration. I’ve looked at the desktop jointers but the reviews on them are all over the place from total junk to the best thing since sliced bread. So I have to manage in other ways.

Option 1:
I can flatten boards with hand planes to some extent. I’m not great at it but I do manage from time to time to get it close. That is unless there’s a twist in the board. If there’s a twist I’m screwed. I do enjoy the work but it causes me to sweat something fierce. I need more options.

Option 2:
I do have a very large jig that I got from one of the magazine that has shims that you adjust to get the board to sit flat. It works surprisingly well but it’s a pain to use, especially on small boards. I’ve considered reworking it to make it more user friendly but it’s still big and heavy.

Option 3:
The Woodwhisper has a podcast episode, “The Jointer’s Jump’in” where he shows different ways of fattening boards. One method he showed was he just used a piece of 3/4 ply and Hot Melt glue to hold the board onto the ply and run it it through the planer. Seemed easier enough. I tried 3 or 4 boards this way. The first one that I planed came out perfect and was easy enough to do. Getting the board loose from the hot melt, that was another story. So I tried a couple of more boards. No matter what I did I couldn’t get a second flat board to save my life. So much for option 3.

Option 4:
I seen lots of different ways of using a router to flatten boards so I thought that I would give that technique a go. I made a couple different AutoCAD drawings of ways of making a jig and ended up using Okham’s Razor and came up with this:

It’s a prototype at this point. I wanted to see if this was going to work before making the long drive to Menards for supplies. It’s just about wide enough to get a 6” wide board in there and a little more than 4’ long. The base was just from the scrape heap, I think it was like 52” long. The sides are some 3/4 MDF that I jointed to be flat and square. The sled is from 19mm BB Ply that also came from the scrap heap.

I routed a 3/4” grove in the middle of the sled so that a router fitted with a 3/4 bushing and 1/2” bit (the biggest straight bit that I have in my arsenal at the moment) could be sit into it. I made the base slightly wider than the base. One fence, the one on the opposite side in the picture, is fastened with screws. The near fence has a little adjustment to it. I made some 3/8 slots in the top and used hanger bolts screwed down into the fence. That way I can use 1/4×20 nuts to move the fence in and out a little, in case it gets a little tight. I thought that I may want a little adjustment in case saw dust builds up between the fence and the rails of the base. It was a good plan!

The way it works is like this, I find the high point on the board and lock the base down. Then I place my ruler under the depth stop and lock that down. This way, I’ll take a cut of about 3/32” from the highest point. I slide the sled back and forth along the length of the base and index the router over each pass taking about 1/4” – 3/8” cut each pass.

I’m quite surprised by how well it works. But then again, I wasn’t sure what to expect. There seems to be a fair amount of people who have at least tried it. The finish is horrible but what do you expect? I guess I expected a less than stellar finish but not quite as bad as I’m getting. I seam to get groves in the board but typically only on one end. So I’m wondering if there’s something out of alignment in the rails of the jig. Don’t know.

Here’s a picture of the groves that I get, hopefully it shows up. The groves are a little easier to see on the far left side of the picture.

Here’s a picture of the underside of the same board that I just flattened:

You can see that I’ve already run it through the planer and planed it hit-skip. I like planing a board that way so that I can see what I’ve got before I do anything else with it.

I still need to run it through the planer and get it all parallel but I think I have something that I can work with. Even with the groves on one end. The board sits flat so I should be able to plane the opposite side parallel and then flip it over and take a pass on this side to smooth everything up.


-- Chunk's Workshop pictures:

5 comments so far

View Northerner's profile


88 posts in 2579 days

#1 posted 09-25-2011 01:45 AM

chunk, what did you use for a bit? i would think some large diameter for doing flat work if there is such a bit?
if not, someone should make it just for this type of use! something a few inches in diameter or more would
make fairly quick work of flattening a board and your right, the simplest way is the best and that jig is perfect
but now its time to make one out of tubing and roller bearings for nice smooth operation???

-- I love the smell of sawdust in the morning!

View Dallas's profile


3599 posts in 1905 days

#2 posted 09-25-2011 01:55 AM

I ran into a warpage problem with some Chinaberry I have to make some small boxes with.
These were too warped to even get in the planer, let alone use a router sled.

I cut the wood into 24” lengths and laid them over the top of a broiler pan filled half full of water, covered with aluminum foil and heated in the oven for a couple of hours at 200°. Once the wood was well steamed, I removed it from the oven and put cinder blocks on top of it as it sat on a flat surface….

It’s been about 10 days now and the wood is still flat and workable!

-- Improvise.... Adapt...... Overcome!

View ChunkyC's profile


856 posts in 2672 days

#3 posted 09-25-2011 01:57 AM

Yup, that’s what I’m thinking of but using angle iron! They do make larger diameter bits. I’ve found one or two that won’t require me to rob a bank first but the 1/2” straight bit is the largest that I have right now.

-- Chunk's Workshop pictures:

View ChunkyC's profile


856 posts in 2672 days

#4 posted 09-25-2011 01:59 AM

Dallas – that should work, but for 8 footers, that’s not going to be practical w/out first cutting them up.

-- Chunk's Workshop pictures:

View docholladay's profile


1287 posts in 2477 days

#5 posted 09-26-2011 03:21 AM

My thinking is that this method would best be used to get the wood close enough to flat that you then can use your planer to smooth it. Personally, that would be my goal for this type of jig. From I see of your jig, it should be plenty rigid to get the job done. Also, you may want to look into one of those bits used for hollowing out bowls – the ones with the rounded corner. First of all, those are designed for cutting on the end of the bit when the usual straight bit is designed for cutting on the side of the bit. Second, it would sort of have the same effect that a slight camber has when using a smoothing plane in helping to prevent plane tracks when the corner of a plane iron digs in. Still, I think it is a bit unrealistic to expect the wood to be glassy smooth using this method.



-- Hey, woodworking ain't brain surgery. Just do something and keep trying till you get it. Doc

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