Bonnie Klein’s Demonstration on February 26 started our 2005 year out in a great and colorful way, turning and painting tops, boxes, turning an acrylic box and demonstrating chatter tool work. I have broken down my experiences into two portions – tools and equipment, and technique.
#1 Tools and equipment: Bonnie uses a negative rake half round scraper and a “square nose” (included angle was approximately 80° as viewed from the top profile) negative rake scraper for all her wood and acrylic boxes. She uses her scrapers without a burr (she removes the burr after grinding). The negative rake eliminates catches. The top of the scraper (as seen from the side view) was ground down ~5°. The tool cutting edge is positioned to cut at centerline of the spindle. She cuts inside and outside threads using a cross-slide jig of her own design (www.bonnieklein.com) which easily and accurately cut 16 TPI internal and external threads.
Bonnie uses 3M Trizact Film to sand her acrylic pieces prior to polishing with Novus #3 Plastic Polishing compound. After the Novus polish, she buffs the plastic with a soft polishing compound on a buffing wheel. She thought the compound was similar to Tripoli, but I know there are special compounds for plastic.
Bonnie only uses cast acrylic – not extruded acrylic. It can be joined together with a solvent or special two-part epoxy. She favors the epoxy but usually turns from solid stock. She gets her acrylic from Delvies Plastic Inc. (www.delviesplastics.com). There are many colors and sizes. She glues them with CA glue directly to a waste block on a faceplate.
All her turnings today used a 2″ face plate with double stick tape to adhere a waste block to the face plate. Clamp the waste block and tape to the face plate for 15-20 minutes to get best results. The tape weakens if it gets hot. The work piece itself is glued to the waste block with medium thick CA glue.
She uses a variety of finishes. Krylon Acrylic Mat spray does not change the wood color, seals the wood and leaves it as a natural finish. Zinser Spray Shellac is used prior to cutting wood threads. Both products may be sprayed directly on the wood and immediately rubbed in with a cotton cloth or they can be sprayed on the cloth and then applied to the wood.
For color dyes, use “india ink” type dyes applied with a q-tip as a brush or use Staedtler or Tombow markers [these are water based]. Apply the markers gently on their sides to prevent blunting of the tip. Bonnie sells the Dennis Stewart Chatter tool with a v-pointed tip for about $40. She has found that the this tip works best. Miscellaneous: Mirrors available at www.bards.com and the magnifying glasses she uses [which are lighter in weight than standard jewelers’ loops] at Robbins Instruments .
#2 Technique: Bonnie used a 1/4″ [This is the European inside measurement of the flute; the actual tool stock is about 3/8″] fingernail grind bowl gouge for most of her truing and turning work in wood. the gouge was tucked under her forearm and into the side of her body to do most of the the outside cuts. Otherwise, it was tucked under her forearm for stability when she removed the center of the box. She always used very sharp tools and always rode the bevel. There was not tear out in the hard maple (end grain) that she was using.
For chatter work, see her article from the AAW’s American Woodturner, March 1996 page 30 [we have it in our library]. When she did a chatter work section (instead of the entire surface) she would define the area with a small groove using the long point of a skew chisel. The tip of the Chatter tool is presented at 90° to the work piece then the handle raised so the included angle is quite shallow. The work is then rotated by hand until the handle of the tool is on the tool rest. This usually happens when the tip is at the 7:30 position (on a clock face). The tool is kept in this same orientation and with the piece rotating at 2300 to 3000 RPM the tool is pulled along that line from the inside to the outside. The goal is to keep the flexible tip at 90° to the work piece so the maximum flutter (chatter) occurs and at the same time have the handle on the tool rest. When turning on the tailstock side of the turning, the tool is moved on an angel that’s between 7 & 8 on a clock. When the tool is placed between the headstock and the turning, the tool is moved on an angle between 4-5 on a clock. The chatter pattern varies with speed, tool force, tool angle and tool movement and is not predictable or repeatable. Have fun and experiment!
Negative angle (rake) scraping tools were used to cut acrylic. Mount the acrylic to a waste block with CA glue and accelerator. Use accelerator on the outside of the glue joint to harden all the glue. After shaping with scrapers, use a skew in the flat position ( a negative scraper) to smooth out any bumps. When preparing a box or lid for threads, make the threaded portion flat and parallel with the lathe bed. Her threading jig makes a thread height of approximately .040″. She uses dial calipers to transfer her measurements form lid to box, and then adds 3/64″ (I don’t understand the 3/64″ adjustment which would result in only a .023″ thread height). In all cases for both internal and external threads, bevel the beginning of the portion to be threaded so there won’t be broken threads. Cut the mating threads a little shallower than you think you need. Its better to cut the threads in 2 or 3 passes in order to get the right fit. (She sometimes saturates the wood with CA glue prior to cutting threads to strengthen the tips.) When cutting threads in cast acrylic she lubricates the cutter with WD-40 and uses water to lubricate when sanding acrylic.
Bonnie reversed turned all her components. She made sure the recess for the jam chuck had a flat square shoulder to bear upon and that the recess was flat and of a constant diameter. This allowed her to cut a tenon or a recess easily with a caliper and a cut-off tool. The jam chuck engagement was usually 1/4″. The fit was tight. She never used a tail stock or tape on the joint.
I have left a lot out, especially her wonderful personality and way of describing her tool techniques, sharing her ideas, knowledge, sources, etc. Watch Russ’s videos [in our library] and see the tops, boxes and fun we all had. It was a great way to start the year. – Al Geller
Bonnie also demonstrated the intentional use of spiral “chatter” that we often produce unintentionally when using the gouge on thin or unstable wood. She says that if we ride the bevel with too much pressure on wood that is able to flex we produce a spiral effect. When we don’t want this, supporting the work piece and taking very light cuts with the bevel rubbing but without pressure will smooth out the ripples. She demonstrated the intentional use of the spirals to decorate egg shaped objects. This is a neat trick and is shown in the photos.
Because of the number of photos we have included they are divided into four sections so they will load faster: (photos courtesy of Ron Lindsay)