How to Make Your Own Unit Blocks

    This is our "Detailed Set" of instructions. Click here for the Simple Instructions.

Warning: The topic covered on this page includes activities in which there exists the potential for serious injury or death. We do not guarantee the accuracy or completeness of any information contained here. Always use proper safety precautions and safety equipment and keep all tool guards in place.

    
    People sometimes write and ask, "How can I make my own set of blocks?"  These instructions will show you how, or you can buy molding below.  If you are arriving here from a link on another site, however, and you really don't know very much about unit blocks, it would be a good idea if you went here first to get a better sense of what you are attempting to accomplish: history page.  This set of instructions is intended for the person who has (at least) some familiarity with woodworking tools and the terms associated with hardwood lumber.

    A serviceable set of school size blocks can be made at home by a practiced woodworker. Aside from gathering materials, expect to spend 20-40 hours at this.  We give directions for making hardwood blocks but the instructions can easily be adapted to making blocks from SPF stock from your local lumber store.   The plan is based on our "Base Set A," and a contents list can be obtained by going to the List of Pieces for this set and printing it.  Other sets are similar, but you will have to re-compute the required quantities of lumber.  

Buy Stock       
    The way to make blocks is simple: carefully make about 100 linear feet of the four sizes of S4S (Square four Sides) molding and chop it into blocks of the requisite length.  This will be more than enough material to make our "Base Kit A" and still eliminate knots and defects. Print our "List of Pieces" for this kit to get a list of blocks.
    If you value your fingers, forget the idea of using all that lovely scrap you've been saving.  We see this foolish idea repeated over and over; it's an invitation to injury.        
    Buy about 35 board feet of Kiln Dried, 8/4 (two inches thick rough lumber) hardwood lumber and about 8 bd. ft of 4/4 (one inch thick rough lumber)  from your favorite hardwood dealer.  #1 and #2C WHAD (Worm Holes are a Defect) should do it. If you can obtain 7/4 this will be cheaper, but 6/4 is usually too small unless it is very robust.  If possible, get the 8/4 lumber pre-planed to about 1-5/8 (both sides) or 1-3/4 (one side).  Get the 4/4 planed to about 7/8.  Hard Maple is the best.  Soft Maple will work but this may vary considerably in quality - particularly Silver Maple.  Oak and Walnut are pretty porous.  Beech is good, but watch for checking.  Birch is okay.  Cherry is pretty but softer.  Poplar is very good but a little soft and often streaky.  Sycamore is excellent but often badly dried and with a lot of tension.  Basswood is too soft.  You can use anything, but consider the investment in time and effort.
    This should cost well under $200.00 for Hard Maple. 

Using SPF and Other Woods
    You can also use SPF (Spruce, Pine, Fir) from the lumber store.  It's very cheap and you can obtain the same footage for around $50.  However, this lumber is always very, very wet (even though it may say "kiln dried") and your blocks will shrink and warp when you are finished.  If you sticker it in a pile, and leave it to air dry for a month or so in a warm, dry place it will shed some of this moisture but it will still shrink somewhat.  The standard for calling SPF "kiln dried" is utterly different than the standard for hardwoods - so don't be fooled.  SPF (particularly Fir) is also considerably more likely to produce splinters.  Whereas hardwood knots are usually sound, SPF knots are usually loose and must be eliminated.  Seek out lumber that is pretty straight and has the fewest knots.
    Needless to say, you shouldn't use treated lumber unless the kids have become a bother.  Be cautious about imported lumber.    Rubberwood is universally soaked in Borates, chemicals that are lethal for cockroaches, and though it's not considered hazardous to young children I wouldn't use it.  Rubberwood is also derived from actual rubber trees and could potentially cause adverse reactions to latex from those who are allergic.  People who sell rubberwood say, "no," so presumably they've fed it to a lot of children and haven't noted any ill effects.  Animals, such as horses, react badly to sawdust from most nut trees including Walnut, Butternut, and the like and these woods are reported to cause some reactions in humans.

Plane the Stock
    Use your planer to plane the thick stock to 1-3/8.  Plane both sides and use a caliper to get it exactly the correct thickness.  Use your planer to plane the thin stock to 11/16.   Use sharp new blades in order to avoid sanding.  Do not trim off the snipe at this time as you will also be using the planer to plane for width at a later stage.

Rip the Stock      Using a sharp rip blade on your table saw, rip the following stock.  You should have plenty of lumber to do this and you can easily end up with extra if your original lumber was high quality.

        50 feet of 1-3/8 by 2-7/8 (Blocks)
        15 feet of 1-3/8 by 1-1/2 stock (Square columns)
        10 feet of 11/16 by 2-7/8 stock (Roof Planks)
        35 feet of 11/16 by 1-1/2 stock (Road Planks)       

    Take pains to make sure that your saw blade is exactly perpendicular to the saw top and that the material is lying flat on the table.  If the material is at all warped, cut it into shorter lengths.  In order to plane the edges you will have to rely on the ripping having been square.  Angled cuts will persist, even after planeing in the next stage.   

Plane the edges
    Use your planer to plane both edges of the wide stock stock to 2-3/4.  Use your planer to plane both edges of the narrow stock to 1-3/8.   Be very careful with the wide, thin stock as this has a tendency to tip in the planer.  If you've gotten this far you should have four sizes of S4S stock, with smooth, perfectly square faces.  At this point be sure to cut off any snipe on the ends as this will haunt you if it gets mixed in with the blocks. 

Rout the edges
    Using a small rounding bit on a router or shaper, round or chamfer the edges of the sticks.  This is easiest on a small router table, but it can be done by hand.  If you use a router table, be sure to use short fences as longer ones will push warped material away from the bit.  Use a sharp, carbide bit and watch the direction of the grain to avoid chip-out.  It is also possible to use a belt sander for the same purpose.  Try to establish an even bead with a small radius (about 3/32").  This is the place where you need to be most vigilant about potential splinters in your stock, so inspect your final work carefully and sand any proud slivers.  Use chalk to mark for elimination any sections where a splinter has made itself apparent and sanding won't remove it.  Customers are usually confused about splinters and suppose them to be the edge frass that sometimes flops around on the end edges after cross cutting and sanding, but this is harmless.  Free floating splinters can't leap up and penetrate the skin even on little hands.  Real splinters are intact tips projecting from the blocks in the long dimension where the grain is separated slightly.  This will hardly be a problem with maple as the cells are too fine, but more substantial splinters may occur in Oak and other woods with bigger cells - particularly Pine and SPF.     

Pause
     You should now have molding more or less in the amounts given above. 

Chop the Blocks
       Chop the blocks to length on your table saw with a crosscut sled or a miter bar using an ultra sharp, carbide crosscut blade (about 60 ATB teeth for a 10" saw).  The object is to make the requisite number of 22 inch, 11 inch,  5-1/2 inch, and 2-3/4 inch pieces.  You can eliminate all of the knots if you wish or, if there are sound knots, leave them.  In general, a simple miter saw won't work very well as it tends toward a lot of edge chipping.  Some of the new sliders may work better, but a table saw is probably the best.  A radial arm saw may also work, but most of them have a lot of slop in the track.
      A carefully set stop is required for repeating lengths.  Take pains to set this correctly and to fasten it firmly to the table top as it will get "tapped" quite a bit and this has a tendency to move it.
      There are some inherent dangers when cutting lots of identical rectangles with a miter bar- particularly small ones.  Use a tall wooden backstop attached to your miter bar and be sure that it is flat.  If it is at all concave, the blocks will tend to pinch inward just as you are finally finishing the cut, the blade will pick up the block on the blade and hurl it toward you.  It is best to provide a back stop that is quite tall (just small enough to fit under the blade guard lid when pushed forward).  Remove or disable the anti kick-back pawls and replace the guard lid with a larger one.  Slit the miter bar backstop specifically for this job and also use a fresh, nicely slit zero-clearance insert in the table top.  The tall backstop will contain most flying blocks (though they may ricochet around a bit) and the insert will reduce the chip out on the edges.  Clamp a fixed length stop to the saw table top for cutting identical lengths.  You may have to undercut the backstop to clear the length stop.  Safety glasses are a must. 
       You should easily obtain the following (more or less):

                4 - 22" Blocks  
                8 - 11" Blocks          
                34 - 5-1/2 inch blocks (you will need some for triangles)          
                18 - 2-3/4 inch blocks (ditto)

    These numbers are a minimum based on the assumption that you are eliminating all knots and dings - if you are more relaxed about defects you can get many more blocks.  Be sure that your lengths are exact, that your sled or miter bar is running exactly perpendicular to your saw blade, and that the blade is dead-on vertical.  Test to be sure that two 2-3/4" blocks equal one 5-1/2" block, etc.  Some additional 22" blocks are good if you have enough material, but avoid the temptation to cut too many big blocks and too few small ones.  The small ones are generally more useful.
   Out of the 1-3/8" by 1-3/8" material (square columns) make the following:
           
                4 - 11 inch pieces            
                8 - 5-1/2 inch pieces            
                8 - 2-3/4 inch pieces            
                8 - 1-3/8 inch cubes

      Out of the remaining road plank and roof plank stock, cut the material in the proportions that you want.  If you copy our list of pieces in the Base Kit A page, you will get a good idea of what you need.  Be sure to cut plenty of roof planks as these are most useful in building complicated designs.  Reserve blocks with a defect in one corner for making triangles.  Reserve blocks with a defect across one face for wedges.  Reserve blocks with a defect in the middle for making arches.  The biggest mistake our customers make in purchasing block kits is to favor sets with mostly big blocks.  This is fine for younger children, but to make really neat stuff a lot of little blocks are needed. 

Triangles, Wedges and other stuff
      Making these pieces requires a band saw complete with a fence, a circle cutting attachment and numerous jigs.  The latter can be made by slitting a piece of Masonite to run along the fence on your Band Saw and then gluing stops in place to hold a blank at the proper angle.  Using a jig and the fence, cut triangles and wedges out of the 5-1/2 inch and 2-3/4 inch blocks by cutting them diagonally.  Because you want the triangles and wedges to end in a blunted lip (about 5/32), the diagonal should be offset at the lip edge by that amount.  You can use the defective blocks (above) for this.  The resultant small half is usually thrown away.
          Arches are cut on the band saw using the circle cutting attachment. It is also possible to use a jig saw for these, but a band saw is really required for the power to cut through 1-3/8 inch material.  Some companies sell arches with a 1-3/8 radius cut out, but we use 2-1/16.  This allows the arches to span a road plank and they look more realistic in making aqueducts and Palladian doors.  
    Trying to cut wedges and triangles on a table saw invites injury.     
    A look at our "open stock" pages will give you some good ideas about what else you can do with any surplus wood.  Here is a place where you may be able to use some of your scrap as the band saw is a much safer machine than a table saw.

Round Columns 
      These are made from dowels though 1-3/8 dowels may be hard to find.   The largest dowels in lumber stores are typically 1-1/4 (Ramen).  Anything bigger is a special order.  Sometimes Closet pole and banister rail material is available in 1-3/8.  This is usually Fir, so be careful about splinters.  If you have a lathe, here's your chance to make some spiffy columns out of anything you want.  While you're at it, make a few onion domes for minarets and churches.

Sanding   
     Sand the end faces, sweep the end-edges, and bump the corners of the blocks to round them on a stationary belt sander or a belt sander held upside down in a vise.  This is very time consuming and requires a sure hand and a good eye to do uniformly.  It helps to have a dust collector attached to the sander and it's best to use a respirator.  Practice on scrap for a little while.  Be sure not to sand too much or your blocks will be shortened.  Some people like a lot of rounding for reasons of imagined safety, but this makes blocks unstable, and I prefer them just slightly softened.  This is a matter of personal preference.  (It's more important, in the long run, to keep an eye on children at play and to nip naughty behavior in the bud).  

Finishing   
     Unit blocks are best left unfinished.  They can be painted with child-safe paints, but it is always a mistake to varnish or shellac them.  In the long run this surface will chip, darken differently than where it is still varnished, and develop a mottled look that is extremely ugly.  Oils are even worse  Most are slightly poisonous and after application, all oils act as an adhesive for dirt.  Painting blocks is like painting the business end of a shovel.  Don't do it.  But if you must, laboratory tested, child safe colored stains are available from the Nazdar company.

Exactitude   
     Considerable care should be taken to assure that sizes are correct and angles are square.  Aside from driving around to gather materials, expect to spend quite a while at this task.  Blocks are a wonderful toy for teaching math skills, but crooked blocks are likely to accomplish nothing but frustration.  A certain amount of random error is allowable.  Be safe with power tools and enjoy yourself.  Don't tell anyone you've made blocks or the whole neighborhood will be stopping by . . .       

    Or   You can buy the molding from us . . . .

End Shape	Type	Price 4 ft.	Buy	for Beg. A*	for Base A*
(    )	Blocks	$7.71	To Cart	4	9
(    )	Sq. Cols.	$5.48	To Cart	2	3
(    )	Road	$4.15	To Cart	1	2
(    )	Roof	$2.29	To Cart	3	6
(    )	Rnd. Cols.	$5.48	To Cart	1	2
* Does not account for wastage. Molding is right off the line, not selected (good or bad), and should be expected to have the usual range of defects and discolored spots and streaks.