Q & A

Easiest Way to Make a Scarf Joint?

My son and I are building a small sailboat and the plans talk about scarf joints for the battens along the side to which the plywood is attached. What is the easiest way to make them? The material is full 1x2. Thank you for any advice you may have. - Robert Manson

Tim Inman: The scarf joint is just a nice easy way to make short pieces longer, so you don't waste a lot of footage discarding short cutoffs. The scarf joint lets you join the shorter pieces together to make longer ones, using a strong and reliable joint.

There are probably many more elegant ways to make this joint, but here is a “rude and crude” real-world working shop method. First, make a sled jig for your band saw. Then, make the long slanted cuts on the band saw. The nicer the blade, the nicer the cut, but don't go nuts worrying about the ”right” blade. Next, make a sled jig for your disc sander. (You do have a disc sander, don't you!? If not, a big belt sander would work, too.) Use the sander to clean up the band saw cuts and produce a nice flat surface to glue. Test the angles on your jig and table relative to the disc. This will be very important to get a good fit, and keep a straight line on your battens. This system easily allows longer angles and hence stronger joints than cutting them on a table saw, for example.

It may seem like a crude way to do it, but it works like a charm, and it is easy, fast and repeatable. I would use an epoxy as my adhesive of choice, since you're looking at marine use. Not only is the epoxy adhesive waterproof, it is also a very good gap filler, in the event my clever little jigs leave you with a little less than perfect joint.
 
A little edge block clamping jig to hold the glue-up while the adhesive is curing would be a nice finish to the batten/scarf jig set. Two scrap boards glued to form a 90 degree corner will make a perfect clamping pad. Wrap the jig or the battens in plastic wrap before you do the clamp-up, though!

Chris Marshall: You also might want to drive a few screws across the scarf joint to reinforce the epoxy bond. It can't hurt to add some mechanical reinforcement, and depending on how you orient the scarf, they wouldn't have to be visible. I'd use good quality, stainless steel screws to avoid any potential corrosion issues down the road … or in this case, river.

Dust Collection: Separator or Cyclone?

I have a 350 square foot shop and am looking to install a cyclone dust collector with five-inch pipe. I presently have a Delta 50-760 dust collector. My question is, should I put a separator on my Delta with five-inch pipe, or should I purchase a Grizzly GO703 cyclone and also install piping? My longest run from either collector would be 12 feet. I will have six blast gates, four -- 90 degree long radius elbows, four Y branches, and about 40 feet of piping. I am looking to run only one machine plus the collector at one time. Space is of the essence so a larger cyclone than the GO703 would just eat up too much shop area. Would appreciate any input. Thank you. - John Michaud

Tim Inman: There is no right answer for this question. It will come down to personal preference. Here's my two cents worth: 350 square feet is a pretty small woodworking shop. That in itself is not a problem. Sometimes I actually wish my shop were a little smaller - so I wouldn't have so much to clean up. But a small shop probably isn't going to ever be a production shop. Huge dust collection equipment might be “overkill.” So, if it were me, and I already owned a dust collector, I would probably just add a separator. Having a bigger cyclone machine would be wonderful, but it does take space and cost more money. Dollar for dollar, I'd rather have some nice new lathe tools. But that's just me. Either of your choices will work. What will work best for you is the most important question - and you're the one to answer it.

Chris Marshall: If your current Delta 50-760 is providing enough draw to keep your machines clear of chips and debris, I agree with Tim — save your space and money for other things. Especially if you are running only one machine at a time and closing off the rest of the ports with blast gates. If the collector is not quite doing the job, and that's your main reason to “trade up,” you might want to contact Delta to see if a different or even larger bag might offer some improved performance. Going with a 5-in. main is a smart idea. I have a similar 1200 CFM Delta collector. My runs are longer than yours, and I've been quite pleased with it. I don't have a separator.

Kiln for Bowl Turning

I have been rough turning bowls, sealing them with wax and also placing them in brown paper bags with the wet shavings to slow down the drying process, and they still tend to crack. I heard of someone making a homemade kiln with a mechanism to warm the inside at a slow rate to avoid cracking. Do you have information on construction of a kiln for bowls? Thank you. - Marty Mandelbaum

Tim Inman: Green wood cannot be prevented from cracking or distorting as it dries, unless the “water” is replaced by something else as it leaves the wood - like PEG, for example. When moisture leaves the cell walls in the wood, the cells shrink. Plain and simple. Controlling (slowing) the rate of shrink helps control the movement and reduces destructive cracking and the stresses that go with drying, but slow drying does not prevent dimensional changes or cracking from happening.

Partially pre-drying your blanks might be helpful. Having a kiln to more totally control the overall drying would be great. There should be internet plans aplenty! Try the AAW [American Association of Woodturners] resources for a start. Another great resource for wood info and drying is the Forest Products Research Laboratory at the University of Wisconsin, Madison. This is the motherlode for wood information. A simple solar kiln might be perfect for you, and they can tell you how to build one.

Here's another thought, though. Some of my woodturner friends have been working with submerging their green blanks in alcohol to displace the water in the wood cells. They feel the alcohol easily exchanges with the water in the wood. They then remove the blanks after several days, and let the alcohol evaporate. They feel the alcohol dries much faster than water, of course - and leaves the blanks with less distortion and less internal stresses than air-dried wood. You might investigate this technique, too. BEWARE! Alcohol is very flammable - and it burns invisibly! You can't see the flame when it is burning! Be careful if you try this.