Polyurethane Varnish Love It or Hate It

Oil based polyurethane is the perfect finish for tool handles like this knob & tote set and it doesn’t have to look like plastic.

I like polyurethane varnish. There, I said it and I mean it.

I’m sure at one time or another we have all heard that “‘poly’ gives wood a plastic look”. What if I were to tell you that that is simply not true? Well, it isn’t true. I use polyurethane varnish professionally on a regular basis and I have never had a customer complain. You can surely end up with that plastic look with polyurethane if you don’t use it properly. Poly’ is like any other tool in your tool bag. When used properly it can be a dream and if not it can be downright ugly.

Let’s take a look at what varnish is actually made of. The main components of any varnish are, resin, a binder, and a solvent. Now there are a lot more chemicals used in the manufacture of varnish by different manufacturers, but these are the main components of all modern varnishes. The main resin used in modern varnishes is urethane or polyurethane, which is a mix of different types of urethane resin thus the poly designation. Before the use of urethane resin most varnish manufacturers used phenolic resins, and some still do, however, the overwhelming majority of modern varnish makers use urethane resin so it is pretty hard to find a varnish that isn‘t polyurethane based. The binder in modern varnish is usually linseed oil and mineral spirits are most often used as the solvent.

Polyurethane varnish offers a very hard, moisture resistant finish which is just what you want for your furniture isn’t it? In order to avoid that plastic look thin your polyurethane varnish at least 50:50. For the first coat or two a 40:60 mix of varnish to thinner is even better. Oil based polyurethane varnish is thick and it has a tendency to sit on the surface with subsequent coats building to that plastic look you want to avoid. By thinning the first coat or two heavily the varnish is allowed to penetrate the wood. Two or three more coats thinned to 50:50 will afford all the protection you need without the build up that full strength varnish gives.

Another thing you can do to avoid the plastic look when using polyurethane varnish is to stay away from high gloss finishes. The high gloss polyurethane varnish can have a tendency to look like plastic. Leave the high gloss finish to the French polish. French polish is a method of finishing that achieves a very high gloss with very little build. It is the heavy build of finish that gives that plastic look. When using polyurethane varnish I stick with a satin sheen. This imparts a rich appearance with none of that plastic look.

The picture above shows a plane tote finished with oil based polyurethane varnish. It doesn’t have that plastic look. I use polyurethane on these totes because they are in severe service and need a hard durable coating that will stand up to body oils, grit and abrasion. Don’t perpetuate the falsehood of polyurethane as so many people have done. Get a small container of good quality satin sheen oil based polyurethane varnish. Thin it as I have described and try it out on a small project. You will find that polyurethane can give you a first class furniture quality finish that is hard, durable and moisture resistant and you will have another tool in your finishing arsenal.

As always thanks for stopping by and please feel free to leave a comment.

Free Wood

The heartwood pieces of some free apple logs after splitting with a froe.

Recently a friend gave me some apple logs from a tree he had to cut down. This weekend I had the time to split these logs. My goal was to eliminate as much sap wood as possible and to break down the logs into more manageable pieces. The picture above shows the logs split and the froe I used to do the work.

Next they will go into the shop and I will saw off more of the sap wood. Then they will go outside under a roof so they are protected from the weather. Here they will spend the summer air drying. In the fall I will rough shape them with a draw knife and turn them round on the lathe. Then they will dry some more in my lathe shop where sometime next winter they will be turned into chisel handles.

Woodworking Get-Together & “Rust Hunting”

On Saturday 4/28, Rick Roberts, a local woodworker hosted a woodworking get-together at his home shop in Ellington, CT. If you frequent the WoodNet woodworking forum you may be familiar with Rick. There he posts under the name RoundToit. The group pooled their money and brought in Steve Branam of the Closegrain woodworking blog to instruct them in making a Roubo try square using only hand tools. Yours truly was invited to stop by for a visit. An invitation I eagerly accepted. Never miss an opportunity to meet new people and learn new things.

This kind of event is really great for sharing knowledge, techniques and skills. You might want to try this in your area. If you do put together a woodworking gathering please let me know how it went.

Last Week’s Pickings

As you may or may not know I have been an old tool dealer for many years. The hardest part of that these days is finding good saleable tools. I haunt the flea markets, auctions, tag sales and estate sales continually.

Above is a little of what I found last week. This lot was found at a local estate sale. There are a wide variety of auger bits. Some made by Jennings and some James Swan. All have the usual tapered square drive for use in a brace, of which I have a few. There are long lengths and standard lengths and short lengths. There are some modern twist bits with the tapered square drive. There is a spoon bit and a tapered spoon bit. This would be good for chair making. There is also a full set plus of tapered wood screw bits. These are a must when using a proper tapered wood screw. On these a straight hole does not give you full thread engagement and therefore you don’t get the holding power that the screw was designed to give.

For those of you here in New England the Brimfield Antique Flea Market, located in Brimfield MA, is opening this week. This is a great place to hunt for old tools, commonly referred to as “rust hunting”. I’ll be there later in the week, hope you pickers leave a little something for this old rust hunter.

If any of you are rust hunters please tell us what you find. I would surely be interested.

Compose a Pleasing Panel

Since the disappearance of wide boards woodworkers have been forced to glue up panels for frame and panel construction, table tops and anywhere else wide boards are needed. I’m not going into the actual glue-up here. There have been many articles written on this subject over the years. Bob Vandyke, the director of the Connecticut Valley School of Woodworking, wrote a very good article for Fine Woodworking Magazine last year. If you need a primer that would be a good place to start.

For this article I would like to pass on what I have learned over my years in the woodshop. The first thing you want to do is select the best boards for your panel. Try to get the entire panel from the same board. This will give you the best possible color and grain match.

I’m sure we have all heard the old “rule” to cut your panel boards to 3” to 4” wide and alternate the growth rings so in one board they are up and the next they are down etcetera, etcetera. This method is supposed to produce the most stable panel possible.  I’m not convinced that this method adds to the stability of the panel. I am convinced that it adds to the ugliness of the panel. Does this rule mean that I should take a beautiful 12 ½” wide cherry board and rip it into quarters and then glue it back together? In my mind that is absolutely insane! I always work with the widest possible boards. The fewer boards in a panel the better the panel looks. After all isn’t the goal to put together a panel that looks like it is one board? As for the up and down growth ring part of the “rule”  simply forget it. Work with the widest boards that you have. Flip them, rotate them and swap their position in the panel until you have the most pleasing panel possible.

Once you have settled on the best position for the boards in your panel mark them in such a way that you can reassemble them in this position. We now need to joint and plane these boards to their final thickness. If you are like me and have only a 6” jointer how do you flatten the first face of your boards if they are wider than 6”? There are two ways to accomplish this. You can use a hand plane to joint the first face or you can use your planer to do this jointing operation. That’s right I said your planer.

Last week I was building a twin screw vise out of rock maple. This maple was by far the hardest maple I have ever hand planed in my life. I was behind schedule and I was in a hurry to get this vise delivered to my customer. My goal was to do as little hand planing as possible to save time and my arms. The solution was an old trick I hadn’t used in a long time. I cut two quarter sawn rails from some scraps of that maple and milled them about 4” longer than the longest board and about 1/8” thinner than the thickness of my boards with the grain running vertical. If you have material thick enough you can make these rails as thick or a bit thicker than the board to be jointed. By doing this you plane the rails and the board. This virtually eliminates planer snipe.

Milled rails being attached to an 8" wide board for jointing in my planer.

The picture above shows the method I use to attach these rails to the rough board. Set the board to be jointed on a flat surface between the rails with the rails extending an equal distance in front of and behind the board. Clamp the rails to the board and be sure the board/rail assembly doesn’t rock. Using screws long enough to penetrate the board 3/16” to ¼” attach the rails to the board.

The board/rail assembly ready to be fed into the planer for jointing.

In the above picture you see the board/rail assembly entering my planer. Take light cuts until you have the board face cleaned enough to sit flat on a flat surface with no rocking. Just as with your jointer the jointed face need not be perfectly clean just flat and stable on a flat surface.

The jointed board ready for removal of the rails.

The picture above shows the board face after being flattened by the planer. From here you remove the rails and continue milling the board as you would any board that has one jointed face. When the board is milled to the desired thickness joint one edge. Then rip the other edge parallel and joint that edge also. You now have a wide board ready for gluing into a panel. Your only limitation on board width now is the capacity of your planer.

Custom Socket Chisel Handles Now Available

Check the For Sale page. The cocobolo socket chisel handles are now available for order. Sorry for the long delay, but I have been literally buried under orders for plane knobs and totes.

There will be a new article soon, I promise.

Processing Your Project Wood

If you use rough sawn wood for your projects there are steps to take that will ensure the wood is as straight as possible when you get to your joinery. This process will work even if it is weeks before you get to cutting the joints.

The first step is carefully studying your project drawing or doing your own drawing. Become familiar with the construction and joinery of the project. You should come away from this step with a thorough understanding of the project as a whole and all of the pieces that make up this project.

Now it is time to make a cutlist. This is a critical step in the building process and one that is too often over looked. I’m not going to go into this step because Robert W. Lang wrote a great article on the cutlist in the April 2012 issue of Popular Woodworking Magazine. I suggest you get a copy of this magazine and read this great article or wait for it to appear online, but please do yourself a favor and read this article.

This is the antique hand saw I use to crosscut my rough boards

You now have a good understanding of your project and you have produced an accurate cutlist. This has given you a familiarity of all the parts, and their sizes, that make up your project. It is now time to select your wood, get it into your shop and start breaking it down into your projects pieces.

I use the antique crosscut panel saw shown above to break down rough sawn boards to their rough length. In the beginning of my woodworking career I used my father’s vintage Stanley tools circular saw. Then I switched to a jig saw. Both were noisy and spewed dust all over the area.

Looking for a better way I sharpened this old saw and gave it a try. I was very pleased with this tools performance. It is quiet and it leaves just a small pile of dust on the floor beneath the cut. This saw has cut 16/4 walnut with ease. Being a panel saw it is a bit short so I am restoring an old Disston 26” crosscut saw for this purpose.

Once the wood is crosscut to rough length it is ripped to rough width. I like to use my band saw for ripping. It is safe and cuts a thin kerf wasting less wood than a table saw. Also, it allows the board to be cut at any angle needed to produce grain that is parallel to the long edges if need be. This is important for parts like table legs, rails and stiles, and table aprons to name a few. This ripping operation can be done with a table saw, but I think the band saw is a better choice. Better yet may be a rip sharpened hand saw. If any of your stock needs to be resawn now is the time for that operation. Here again the band saw is my tool of choice for the same reasons stated above. Of course there is no reason that resawing can’t be done with a hand saw.

After allowing the parts to rest and acclimate they are now ready for jointing and planning. I like to do this operation in two stages, rough and finish. However, if there is a large amount of material say ¼” or more, to be removed three stages would be better. These would be rough, semi-finish, and finish, allowing at least a day preferably more between operations.

All wood has internal stresses caused by many things that it has encountered throughout it’s journey to your shop. Every cut we woodworkers make on a piece of wood releases some of these internal stresses causing it to move in unequal ways. Thus we end up with cup, twist, warp or crook or any combination of these. This movement can be very minor or very great depending on the degree of stress involved. This is why I process lumber from rough to project ready in stages and advise you to do the same. Allowing the wood to rest between milling stages gives these stresses time to work out before going to the next operation.

My preference is for air dried wood. Bread is baked. Wood should be air dried. The finest furniture the world has ever seen was made from air dried wood. I may not be able to reproduce the quality of the old masters, but I certainly can use the same wood. This is just my opinion and there are many who would disagree with me. Usually wood that has been properly air dried exhibits less internal stress than kiln dried, but that is not a rule.

Here is some project wood awaiting the next milling step

Whenever I have my project wood resting between processing stages I have it “stacked and stickered” as you can see in the picture above. This allows air to circulate completely around the boards. Thus they can “breathe” equally from all sides minimizing movement. When possible I will even stand boards on edge to allow complete exposure of the large sides. Never leave a board lying flat on your workbench for an extended period. This can cause a board to cup from unequal moisture movement. Moisture can move freely from the boards exposed side, but is drastically slowed on the side in contact with the workbench.

For the “stickers”, the sticks placed between the boards, I use 1” x 1” of whatever I have on hand. Just be sure it is thoroughly dry. Never use green wood for stickers.

Whether your wood is air dried or kiln dried if you process it in stages as I have outlined here you will have fewer problems and you will achieve better results. The other method that I have used that also works well is the fast method. With this method you work as fast as you can and go directly from finish milling to joinery and glue up. This method does not give the wood time to move before it is constrained by the joinery. Many professional furniture makers use this method. For me working in stages is my method of choice.

Thanks for coming by and let me know which method works for you.

The Modern Thread Box

This is the 1"-6TPI thread box set and the tools you will need to properly adjust it.

 

In a recent article about the Beall wood threading system I mentioned that I had previously been working with a modern thread box set to cut male and female threads in wood. I think this system merit’s a closer look as it is a very good way to cut threads in wood inexpensively.

The opening picture shows the 1” AMT thread box set that I use to make threads for the “Mini Moxon” twin screw vises that I make. This set, along with several others was purchased at an auction many years ago and sat on a shelf until recently. AMT is not in business anymore, but these thread box sets are still being made and sold by many woodworking tool suppliers and they come in sizes up to 1 1/2″. I looked at one in my local Woodcraft Store and it appears to be about the same as my set.

The set includes the thread box made of maple I think, the taper tap and handle and instructions. As shown you will also need a small screwdriver to remove the guide block from the thread box and a wrench to loosen the thread box cutter for adjustment.

Here you can see the tap in use on red oak.

 

I recommend cutting the internal threads first.  Then you can adjust your thread box to cut an external thread that fits your internal threads properly.

Most large taps for wood are designed to be used with a drilled hole 1/8” smaller than the large diameter of the tap. I used a 1” tap so I drilled a  7/8” hole. This hole, for most uses, needs to be perpendicular to the face of the wood it is drilled into. I recommend using a drill press for this operation.

Care must be taken starting the tap. You must get it started straight. The taps have a straight diameter about the size of the drilled hole and taper up to full size. This helps you to start the tap straight and to get it cutting straight.  Use a couple of squares set 90 degrees apart and sight your tap parallel to these if you need to. Once you get the tap started it will tend to follow the hole.

Be prepared to use some muscle. It takes a lot of power to turn a large tap into hardwood. On the red oak shown I used a couple of 10” long pipes on either side of the tap handle for some extra leverage.

In this picture you see the taper tap that comes with the set and the optional bottom tap.

The tap that comes with the thread box set, (the top tap in the picture above) is designed for tapping through holes only. There is a special tap (the bottom tap in the picture above) that is designed to tap blind holes.

I have not found that lubricating the tap helps ease the force necessary to tap a hole or improves the finished thread in any way. However, if you wish to use a lubricant I think mineral oil would be best. This oil won’t get gummy, as linseed oil might.

The thread box in use cutting a walnut screw.

 

The tap that comes with the thread box set, (the top tap in the picture above) is designed for tapping through holes only. There is a special tap (the bottom tap in the picture above) that is designed to tap blind holes.

I have not found that lubricating the tap helps ease the force necessary to tap a hole or improves the finished thread in any way. However, if you wish to use a lubricant I think mineral oil would be best. This oil won’t get gummy, as linseed oil might.

This picture shows the inside of the thread box looking from the bottom through the guide block.

 

If the tool begins to bind and turn very hard stop and turn it counter clockwise to remove it from the work. It needs to be adjusted. In the above picture the guide block has been removed so you can see inside the thread box. You can see the cutter coming in from the right. Below the cutter you can see a threaded aluminum bushing. When the first cut thread enters this threaded bushing the bushing’s internal threads engage with it driving the tool down so it can continue to cut the threads. If the cutter is not cutting deep enough the cut thread is to big to fit into the bushing causing the tool to bind up.

Here you can see the bottom of the tool. Notice the registration mark on the guide block and the body of the tool.

 

This insides of the thread box with the guide block removed. The cutter comes in from the left.

 

To adjust the thread box cutter first remove the guide block, shown in the upper picture above, by taking out the two screws that hold it to the thread box. Before removing the guide block I suggest that you put a mark on one end of the block, also shown in the upper picture above, and the thread box body. This ensures that you can replace the guide block in the same position, insuring the same alignment as when it was manufactured.

With the guide block removed turn the tool over and loosen the brass nut on top. This nut tightens or loosens the cutter so it can be adjusted or removed. With this nut loosened use a small screwdriver behind the cutter and gently pry the cutter forward. Make very small adjustments. Too big an adjustment can cause the cutter to cut too much and damage it. If your thread box was cutting a thread that was too loose in the female thread gently pry the

cutter in, away from the threads, using something softer than the cutter such as a wood pencil. Replace the guide block and try the cut again. When re-starting the cut turn the thread box counter clockwise until you feel it drop down into the previous cut. Then begin the new cut. If the tool still binds stop the cut and go through the above adjustment procedure again. It may take several adjustments to get it right. That is why you use a scrap dowel for setup. You don’t want to ruin a good work piece.

The external threads should turn freely into the internal threads, but not too loose. You need to allow for wood expansion if you are doing this in a dry season. The fit can be a little tighter if you are doing this in the humid season.

The instructions that came with my AMT thread box sets gives recommendations for wood species to use. They recommend yellow birch, hickory, ash, poplar, cherry and walnut. The instructions also specify woods NOT recommended. These woods are hard maple, oak, paduak and rosewood. I have tapped red oak, but I would not try to use the thread box for external threads in this wood. I have also tried the thread box on hard maple. This resulted in a big chip in the thread box cutter.

This is a parallel jaw vise I made using the thread box set.

 

The modern thread box and tap sets do a very credible job of cutting both internal and external threads and they are a lot of fun to use. The list of possible projects is almost endless. I used my 1”-6TPI (threads per inch) set to make the parallel jaw vise pictured above. The jaws are red oak and were not bad to tap. The screws were made from walnut and the thread box did a very good job on them. If you are new to this blog I wrote an article on this vise a while back. It is a very handy and versatile tool. I use it very often. Look in the index if you are interested in this vise or LMK if you would like me to make one for you.

Because of their wood species limitations the thread box would not work for me. My desire is to make quality wood screws and nuts for vises and the wood of choice is hard maple.

To date I have tried two different methods of threading wood and neither produced the results I am looking for. In both methods the taps, though very different worked well. The problems each of these methods presented was with the external threads.

For my next threading project I will mount a router to a vintage engine lathe. I know this setup will produce a near perfect male thread with perfect pitch in any species of wood. This will eliminate all of the previous problems.  Because of the work involved I will go all the way on this project and develop a 90 degree thread profile. This will require that I make a tap because no taps are available for this profile. The 90 degree thread profile has long been accepted as the strongest thread profile for wood threads.

My current workload means that this project is going to take a while. When finished I will publish the complete results here.