Wood preparation tips 1
Precision is key
I recently finished an end grain cutting board that I recently finished. In response to a couple of questions from other members who saw me in the process of building it, here are some build notes that may be of help.
I am not going to describe how to build edge grain cutting boards here - there are enough videos on YT that describe how to do that. Instead, I would like to focus on “precision” since even the minutest variations in the lumber will become glaringly obvious, given the nature of the multiple glue-ups involved.
I began with rough lumber on this project, so milling was key. It is good to keep the pieces long for reasons that will become clear below. When you rip long pieces, even you have S4S lumber, you will very often relieve tension inside the wood and the newly cut pieces will warp. To counter this effect, mill the initial lumber over size. That way, you can rip, let the lumber settle into its final state, and then mill again down to final size.
And remember, in projects like this “EQUAL is more important that EXACT”. I wanted this cutting board to be 16" x 16" and had sized all the component pieces accordingly in my plans. However, a couple of pieces had to be milled down to slightly smaller dimensions than what was in the plan. And that was fine because I milled all the pieces to be equal to those smaller pieces. This is a very important concept to remember more generally. For example if you need to make two mortises in a piece to fit a tenon-ed shelf, use a spacer block (rather than exact measurement) to mark out the openings. It does not matter whether the openings are 2.25" from each end, or 2.125". If you use the same spacer block to mark out the mortises and corresponding tenons, you will be just fine. When I first began woodworking, it took me a while to internalize this concept.
Here is the most important aspect for this type of project: as you do the final milling, and in the subsequent cuts, your biggest enemy will be snipe (true in most projects). The bulk of my attention in this project was to try avoiding it at every stage. As I mentioned, the glue-ups in an edge grain cutting board happen at multiple levels. The best surface to glue is one that has been jointed - so, mark all the surfaces that have been through the jointer and try to preserve them as much as possible. I did not use the planer even once in this entire project. In the past, I have tried every trick in the book to pass lumber through the planer without snipe and all my efforts failed. Some techniques minimize snipe, but I have not been able to eliminate it entirely on a consistent basis. The snipe in our planar occurs within 5" from each end. So, generally I just add a foot of board length to everything I mill, finish the process and just trim the sniped ends down to final size.
In this case, I was dealing with valuable wood and there are multiple steps to clean up the pieces. So, cutting 5" off each end at each stage was not viable. Therefore, all the milling was done initially using the jointer and table saw. You can get good results from just doing that. Except, a surface produced by a table saw is not the best for gluing. Therefore, I ran the pieces also through our drum sander, Guess what - the drum sander has snipe! The way to minimize this is to get the drum to just kiss the wood and then adjust it down 1/128" at a time. Yes, this is laborious, but mark my word that you will be glad you did. You can start with 60 grit on the drum sander and go more aggressively if you want more removed initially, but use the technique above (with say 120 grit) to get down to the final size. Remember: take small cuts on all machines whether the jointer, planer or drum sander. On the table saw, if you want a clean rip (ie. smooth surface and without burn marks), first cut it down to say about a 1/16" larger size and then do a final trim to final dimension.
A word about cutting on the table saw - I had to rip 2.5" pieces on this project. The blade on the Sawstop goes all the way up to 3". However, do not attempt to do this cut in a single piece if you are using dense hardwood. You will hear the saw struggle and the heat generated will leave burn marks on the wood. Cut half-way, then flip the board over with the same surface against the fence and finish the cut. You - and the saw - will be much happier.
If you made it all way through reading until here, thanks!
Notes on Snipe
On the planer the lever to the right of the bed controlling the rollers in the bed is key. The more the lever is pushed down the greater the snipe. It is rare wood will feed smoothly through the planer with the lever all the way up.
On the drum sander it Is about maintaining the wood in a perfect plane and constant speed through the sander. The MN drum sander doesn’t even have the inadequate optional in and outfeed platforms. I think it would be extremely difficult to avoid snipe entirely. My recommendation with this drum sander is to get an assistant so one person supports and assists the wood entering the sander and another supports the wood exiting. Minor speed variations or a drop of an 1/8 at the end of a long plank is enough create detectable snipe-like defects.