Problem Solving Products: Issue 24Comments (0)
This article is from Issue 24 of Woodcraft Magazine.
Cozy Up to the Critter
THE PRODUCT: Critter 118 Siphon Gun
WHAT IT DOES: Simple spray gun good for a wide range of materials.
AVAILABLE AT WOODCRAFT: #128235
TESTER: Craig Bentzley
The Critter isn’t a warm and fuzzy mammal, but it does resemble the smaller Badger airbrush that I’ve used for touch-up jobs for many years. In technical terms it’s a single action, external mix, bottom feed spray gun. The question is, for fifty bucks, can the Critter deliver the goods?
The gun comes with one jar and a 1/8" NPT quick-connect plug, so in theory, it’s good to go right out of the box. Fill the jar, attach it to the gun, hook up an air supply, and you’re set to spray. (My 2 hp, 4-gallon pancake compressor had no problems keeping up with the gun, although it cycled frequently.) To avoid contaminating your finish with any moisture or oil that may be in your compressor, you’ll want to attach an inline coalescing filter if you don’t already have one.
In terms of spray-gun technology, this is about as simple as it gets. Pulling the trigger causes air to flow over the fluid nozzle, creating a pressure drop in the siphon tube, which draws the liquid up the siphon tube. When the liquid exits the liquid nozzle, the air stream atomizes it and directs it onto your work. The resulting round spray pattern averages about 21/2" in diameter when the gun is held 6" from the workpiece.
Despite, or maybe because of its simplicity, delivering just the right amount of material isn’t always easy or intuitive. The instructions that come with the gun help, but you’ll still need to do some experimentation. I suggest working out your fluid nozzle adjustment and regulator settings on a piece of cardboard before spraying your project.
There are only three ways to control the amount of product applied. The first way is to adjust the fluid tip. The second is to regulate the amount of air pressure at the compressor, and third is to manipulate the viscosity of the finishing material itself. I got the best results when using the lowest air pressure you can get by with. Higher pressures create overspray that produces an unattractive finish and wastes material.
First, I tried spraying a water-soluble dye. Despite what it says in the manual, 30 psi was way too much pressure; even at 20 psi, there was still too much fluid leaving the nozzle. The gun performed acceptably only after bottoming out the fluid nozzle.
I tried a 2-lb. cut of shellac next. Since I felt more comfortable with the gun, I nudged the pressure up to about 25 psi and left the fluid tip alone. I quickly built up a finish with five successive coats. When dry, the finish had some mild orange-peel but it was easily rubbed out with 4/0 steel wool.
Climbing up the viscosity ladder, I test sprayed an alkyd satin polyurethane varnish. With the regulator set at 25 psi, I only had to raise the fluid tip about one-quarter turn to get a nice spray pattern. I applied three coats with excellent results.
Finally, I decided to torture-test the Critter with a thick satin latex paint. At 35 psi, even with the fluid nozzle raised to its highest recommended point, the gun sputtered and spit like a rabid cobra. I thinned the paint with about 10% water, and it behaved for awhile. Soon the fluid nozzle began to clog. The solution to this problem was to mix in some Floetrol, an additive that helps paint flow better and extends the drying time.
The Critter can be used to spray just about any liquid such as adhesives, cleaners, and bleaches. The manufacturer even offers a stainless steel siphon tube for handling corrosive liquids. It’s a great gun for applying stains, sealers, and alkyd varnishes. It would be hard to beat for patio furniture, interior trim, and general staining. For high-end finishes like lacquer, you’ll want a gun with more control.
The best thing about this gun is the small number of parts. This translates into fast, easy cleaning. Just fill an extra jar with the appropriate solvent, put it on the gun, swirl it around a bit, spray it for a few seconds, and you’re done. For a more thorough cleaning, you can do a complete breakdown with just a small adjustable wrench. Pipe cleaners work well for cleaning latex paint out of the siphon tube.
I wish the siphon tube was a little longer. It hangs about 3/4" from the bottom of the jar so you’ll never come close to emptying it. I would also have appreciated a few spare gaskets. Mine held up for the test purposes but I suspect it won’t last for long.
There is a bit of a learning curve to using this gun effectively, but it’s a handy piece of equipment if you don’t want to spend big bucks and don’t mind some tedious adjustments. You wouldn’t want to use one on a Steinway, but because it’s suitable for all sorts of smaller projects, I can see these Critters lurking in a lot of workshops.
A Different Spin On Lathe Motors
THE PRODUCT: Nova DVR XP Lathe
MADE BY: Teknatool
WHAT IT DOES: Turns wood by means of a unique motor design
AVAILABLE AT WOODCRAFT: #146719
TESTER: Ken Kupsche
Manufactured by Teknatool in New Zealand, the Nova DVR XP falls into the heavy-duty class of woodworking lathes. Its massive cast iron components, expandable bed segments, extra-large ball bearings and extensive line of accessories appeal to all serious turners. Its best feature is one you can’t see–the DVR motor built directly into the heavy cast-iron headstock, resulting in virtually non-existent vibration.
But first, here are the basic specs: The DVR XP has a 16" swing and is 24" between centers. The headstock spindle is 11/4" in diameter with 8TPI (threads/inch) and having a #2 MT (Morse Taper). The headstock swivels 360° and features a 24-division spindle index. The cast-iron tool rest measures 12" long with a 1" post. (A 3" faceplate comes with the lathe, but a stand will cost you another $150).
The Digital Variable Reluctance (DVR) motor, as shown on page 72, is what makes this lathe really special. Originally designed for jet aircraft, the motor has just three basic parts: a microcomputer, a rotor, and a stator. Say goodbye to out-of-balance pulleys or slipping drive belts.
Here’s how it works. The rotor is basically a spindle bearing steel laminations, much like a gear. The stator surrounds the rotor with a series of strong magnetic fields that flip on and off sequentially to spin the rotor at a very precise speed.
The microcomputer controls this speed while also monitoring load and torque. By analyzing spindle speed hundreds of times a second, the computer senses when cutting pressure is being applied and adds power so that speed remains constant regardless of the cut.
This lathe comes assembled, but you’ll need help to lift its 190 lbs. out of the box and onto a stand. Wipe off the grease, attach the toolslide and tool rest, put in the centers, and you’re ready to turn.
The microcomputer’s programmable speed function lets you preset five of your preferred turning speeds. After years of pulling belts on and off pulleys, I found DVR’s speed range–adjustable from 100 to 3500 rpm in 5 rpm increments–a little overwheming. However, after a few cuts, I quickly found speeds to match the feel of my cuts and turning stock.
After roughing out a bowl, I tried to bog down the motor by leaning in for a really heavy cut–but the DVR motor never skipped a beat. The lack of vibration and smooth power feed seemed to improve my finish cuts, and the cone shaped headstock made it very easy to get behind my stock and right up to the edge of the faceplate.
Like most lathes in this range, the DVR is designed to handle bowls, spindles, and just about anything. And bed segments are easy to add to expand its capability
I was a little disappointed that the basic package did not include a stand, and the 24" between centers seemed pretty short. That said, you can build or buy a good quality stand, and, for a reasonable price, purchase 20" bed segments that expand the length between centers. And with a few bags of sand as ballast, you can solve the weight issue just as well.
The DVR motor puts this lathe in a class by itself. The programmable, speed-sensing and auto-adjusting features are unlike any other, and the advantages offered by the motor far outweigh any negatives.
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