Best practice for getting exact thickness wood needed

[Van Huskey]

I can't see any way to avoid putting the slab back through the planer after every board is cut from it or I'll have to take each board to the jointer to get one good face and then send it through the planer. I guess either way works.

With a decent bandsaw that is tuned properly and running the correct blade you should not have to reface the board/slab between resaws. I usually cut veneer at 1/32 or 3/64" and can cut 20+ sheets with no more than .005" variation across each sheet and that is being conservative, usually better.

In any case 5/16" should be plenty to have finished boards at 1/4". If your saw and fence are correctly tuned and using a proper blade for the cuts your variation should be well under 1/32", that's actually doable freehand without a fence on a short board. That said the easiest thing to do is experiment yourself and determine where the line is for your machines and your skill, you may find you need a lot less margin for error or you may find you are more comfortable giving yourself a little extra wood to work with.

[Dan Hahr]

If you were that specific and he can't cut any better than that, you need to stop dealing with him. If you have a planer and table saw, you should be able to resaw 6 inches easily from 3/4 inch boards and have twice as much wood.

Dan

[Jim Becker]

While clearly the only way to assure that your material thickness is exactly what you want/need at the exact time you need it is to do the milling yourself, I agree with the comments that you have a supplier issue. I think you understand that from your last post. Were I you, I'd be investigating new suppliers, both to insure you get what you order as well as to not be paying for material you're not receiving.

[Art Mann]

Paul,

I do this same kind of work all the time and what you are proposing to do is precisely the way I do it. I use a CNC router to engrave, cut inlays, and make small wooden and HDPE parts, among other things. The thickness of the stock needs to be the same kind of precision that you are looking for. The only way I have ever been able to get this kind of precision is to machine the wood myself. My process is simple. Resaw thick material to a little over size. Run both sides through my thickness planer. Run both sides through my drum sanders, 120 grit and 150 grit. I will often just skip the planing step and just sand to thickness if I have done a good enough job resawing.

I don't think you will ever be able to control dimensions as accurately as you need unless you do it yourself. It is just takes too much trouble and too expensive for some other supplier to hold these tolerances.

[John C Cox]

The issue sounds to me is that while your vendor may be well intentioned - he doesn't have the skill/setup to resaw like this.. He may be used to milling lumber... It sounds like his equipment is not well setup or he doesn't commonly resaw for dimensional accuracy. A dull blade or a blade without enough tension will wander and leave thin spots.

It's a common problem... There is significant learning curve involved. And you are paying for his learning curve.

If you continue to deal with him - make written contract provision that you will reject all material under your minimum thickness but you will still pay for it if it's too thick - say -0/+1/16" o even +1/8".

If you decide to resaw yourself... There is a learning curve. There is a lot of material loss. And early on - you will waste an aweful lot of material. There's also ongoing cost. Resawing relies upon the band being fresh and sharp.... And that means you will have a constant ongoing expense with buying new bands. A band will waste a lot of wood when it starts going dull.

I personally use a wide drum sander to clean up the wood and hit a finished thickness.

I will give you an example of my own.... I don't do a whole lot of resawing. I make acoustic guitars... The plates are generally finished to 0.100"-0.150". I saw for 1/4" total slices including my saw kerf and all clean up. I generally end up with smooth 80 grit sanded wood somewhere between 0.140" and 0.180". So a true 1" board gives me 4 pieces.

I do this because having pieces too thin means they are scrap... Too thick means more time in the drum sander. To clean them up...

I run into all sorts of trouble when I get greedy..

[lowell holmes]

I have a 6" jointer and a 12 1/2" planer.

I flatten and joint a 1X6 board to square and flat. I will plane wider widths by running one side of the wide board on my 6" jointer.
This leaves a 6" surface that is flat and straight. I attach a 1X6 completely square and flat to the 6" planed surface on the wide board.
The boards are joined to each other with double sided sticky tape.
I run the wide board on the 12 1/2" planer with the squared 1X6 attached to the 6" wide flattened surface on the 12" board. This leaves me a full 12" wide and
square board on one side. I turn it over and plane it in the planer, leaving the 12" board flat and square.

I keep the 1X6 to do it again if needed.

Try it, it works.

[John C Cox]

I am sure you know this already.....

Watch out out for trying to use planers on thin stock. There's a very fine line between going smoothly through the planer and Kaboom - wood shards everywhere. That's where a drum sander wins the day. This is a common problem with guitar wood.. Granted - our stock is considerably thinner than the 1/4" you are talking about.

[Bruce Wrenn]

After taking a couple classes on metalworking, my woodworking standards have become much, much more exacting. I use a high quality digital caliper now and to me, 3/4" thick means that it needs to be within 0.005 of 0.750.

Wood ain't metal! The changes in humidity overnight can change your stock size by SEVERAL thousandths.

[Paul K. Johnson]

I am sure you know this already.....

Watch out out for trying to use planers on thin stock. There's a very fine line between going smoothly through the planer and Kaboom - wood shards everywhere. That's where a drum sander wins the day. This is a common problem with guitar wood.. Granted - our stock is considerably thinner than the 1/4" you are talking about.

I use hardwood as thin as 1/32" but that's for hobby purposes. For the tools I make and sell, 1/4" is the thinnest.

I made a bunch of rocking horses a few years ago as Christmas ornaments. Then I made a few that were half that size. They had 1/8" thick bodies and 1/16" everything else (mane, tail, legs, rockers). I then drill through the bottom of the rockers into the leg and inserted a pin. The horse is about the size of an old silver dollar. I'll post some photos some day.

[Art Mann]

Wood ain't metal! The changes in humidity overnight can change your stock size by SEVERAL thousandths.

If you use the widely accepted "shrinkulator" calculator on line, you will find that the change in the tangential dimension of wood that is 0.25" thick is too small to calculate, even if the moisture content changes by a wildly improbable 1% overnight. I mill lots and lots of maple, walnut and cherry lumber to 0.313". It won't change enough to measure the difference on my digital calipers for several days. I know because I verify thickness every single time before I begin CNC carving. Just because you don't use stock with this kind of accuracy doesn't mean nobody else does. Over time, warpage is a more serious problem but that doesn't happen overnight either if the stock is kiln dried. I am sorry to be so blunt, but I make money doing this all the time and I know what I am talking about.