Double Axis Square Turned Bowl

Transcription

1 Duble Axis Square Turned Bwl Thames Valley Wdturners' Guild Presented by Paul Newtn

2 INTRODUCTION Yur Presenter: Paul Newtn has been wdturning fr apprximately six years. He is a member f the American Assciatin f Wdturners, and is currently President f the Thames Valley Wdturners' Guild in Lndn, Ontari. He has demnstrated turning techniques at Guild meetings and Lee Valley Tl wrkshps. His turnings include bwls, vessels, spindle wrk, wine stppers, and art pieces. Histry Wdturning bwls is a craft that has been passed dwn thrugh generatins, with the earliest knwn examples being ver 4000 years ld. Befre the metal age, and the industrial revlutin, vessels fr eating and drinking were mstly made f wd r ceramics. The earliest f these were carved bwls and cups. Later artisans learned t "turn" wd n early ple lathes, creating mre unifrm shapes. With advent f the industrial revlutin, turned wd items declined in use in favur f metal and ceramic bwls. Wdturning enjyed a resurgence beginning in the mid twentieth century, and is presently enjying immense ppularity wrldwide as bth a prfessinal art frm and a ppular hbby. The American Assciatin f Wdturners was frmed in 1986, by a small grup f American (and Canadian) wdturning artists. Tday the AAW basts ver 15,000 members, and a netwrk f ver 350 lcal chapters wrldwide.

3 Intent f this Seminar In this seminar we will be turning a Duble Axis Square Turned Bwl. Subjects will include: Lathe safety Bwl design Preparing and munting the wd Turning the bttm (2 axes) Making the jig Munting the bwl Truing the face Turning the inside f the bwl Finishing Tls and Materials Required Bwl blanks 6"x6"x3" Maple (2). 6"x6"x ¾" Wd Spacer (slid wd nt plywd r MDF) Sharp turning tls ½" r ¾" Standard Grind Bwl Guge ½" r ¾" Fingernail Grind Bwl Guge (Elleswrth) Spur Drive / Safety Drive fr munting the wd. Live Centre fr the tailstck. Munting Jig 2x4 framing lumber (24") 12"x12"x¾" plywd Wd screws and Titebnd Glue Steel faceplate r 3½" x 3½" x 1½" thick Maple t make a wd faceplate Drill & Tap (Beall Tl) CA glue Ht glue (gun). Sandpaper (120 / 240 / 320 / 400 grits). Finishes Gess Liming Wax Tung Oil Rubber Glves SAFETY GUIDELINES Wear Prper Attire! Always wear eye prtectin. A face shield is the best methd f eye prtectin. Lse clthing and hair are dangerus because it can get caught in the spinning lathe. Tie back lng hair, and wear clthing with shrt sleeves r rll up lng sleeves. Remve jewelry and watches and rings as they can get caught up in mving parts. Be aware f the dangers f breathing wd dust. Wd dust is dangerus when inhaled in quantity. Prlnged expsure t wd dust can cause respiratry ailments. Wear a dust mask r respiratr when sanding wd. Mst finishes are nt safe t breathe and precautins shuld be taken t avid inhaling their fumes. A gd respiratr rated fr finish-type chemicals wuld be a gd

4 investment in yur health and future mental capacity. Be aware that chemical respiratrs have a limited functinal shelf life s the filters shuld be changed when necessary. Keep yur fingers and bdy parts ut f harm s way. The tlrest n the lathe shuld be as clse t the wrk as pssible s that yur fingers will nt get caught between the tlrest and yur wrk (⅛" t ¼" wuld be safe). Get in the habit f blwing the dust and shavings ff the tlrest instead f wiping it ff with yur fingers. Using yur fingers t clean ff the tlrest might cause yur fingers t get caught between the wrk and the tlrest. Always turn the lathe ff befre mving the tlrest. This prevents harm nt nly t yur wrk but als t yur bdy parts. D nt wrap sandpaper r buffing/plishing rags arund yur fingers r hand. If the clth gets caught in the spinning parts f the lathe, yur fingers will be pulled int the lathe. Use paper twels fr applying finishes. Paper will tear ff if caught in the lathe. Check t see if pieces are securely held in the lathe. Check again! Rtate piece by hand and check t see that it rtates freely and des nt cntact the tl rest. Pay attentin t, and use the prper lathe speed. When in dubt, start lathe n slw speed and increase after yu are sure all is OK. Befre turning n the lathe, always duble check the speed setting. Als be sure t check that the drive belt is n the prper pulley fr what yu are turning. Turn at a speed that is cmfrtable fr yu and is apprpriate fr the wrk. A gd rule f thumb fr prper lathe speed, (Craft Supplies Wdturning Catalgue), is that the prduct f the diameter f the piece times the lathe speed in rpm s shuld fall smewhere between 6,000 and 9,000. Fr example, a 10"-diameter turning times a lathe speed f 800 rpm s equals 8,000, which wuld be a safe speed as 8,000 falls between 6,000 and 9,000. Larger, r mre ff-balanced items shuld be turned at slwer speeds. Stand clear when starting up lathe! Listen t yur inner vice if it desn't feel right; dn't d it! LET'S GET STARTED Lathe Tls & Usage: Use nly thse tls meant fr the apprpriate task. Fr bwl wrk use bwl guges, scrapers, parting tls (spindle guges may be used fr detail wrk n the utside) A Spindle Rughing Guge is fr spindle wrk nly NOT FOR BOWLS!! Make sure yur tls are prperly grund and sharp. Observe the 'ABC's f Wdturning (Anchr Bevel Cut) Understand the tl angle and the cutting angle fr each tl. Take small cuts t start with dn't be t aggressive. Cut dwnhill always have fibers supprted.

5 Step One Prepare and Munt the Blank Cut 2-6"x6"x3" bwl blanks and the 6"x6"x3/4" spacer. The 2 bwl blanks will eventually result in 2 bwls. The thickness f the blanks must be ne half f the width, in rder fr the dimensins t wrk ut. Examine the blanks first; check fr cracks, bark inclusins and ther faults. If the wd is "punky", r cntains ne r mre f these faults, discard it. Line up the 2 blanks with the spacer between them. Using Titebnd, glue the three pieces tgether and thrughly clamp all pieces. Allw glue t dry vernight. Mark and draw a line alng the central axis f the spacer bard n all fur sides. Find and mark the centre f the line n all fur sides, and using an Awl, make an indentatin at the centre. Using a cmpass mark the intended diameter f the circle yu will turn (6"). Draw 45 degree lines acrss the crners apprximately ¼" frm the circle. Allw fr sme turning.

6 Using a bandsaw, cut alng the 45 degree lines and remve the crners. D nt discard the triangular pieces. Yu will need them later. Trim ther crners t allw fr easier turning. Munt the blank n the lathe between centres using a safe centre in the headstck and a live centre in the tailstck. Stand clear when starting up lathe. Start lathe n slw speed and increase after yu are sure all is secure. Increase speed t a level apprpriate fr the wrk and yur skill level.

7 Step Tw Duble Axis Turning Set n slwer speed when first starting t shape the bwl. Speed can be increased as the wd is shaped t run balanced and true. Using a bwl guge, begin runding the piece acrss the face f the blank. Take small cuts and maintain the parallel face. Cntinue until yu have turned the piece rund t the spacer. Use a caliper and check t make sure the diameter is cnsistently the same acrss the piece and at bth ends. If yu intend t sand the bttm smth, yu must d it nw. Rtate the piece 90 degrees in the lathe and munt between the ther tw marked centres alng the spacer bard. Using the bwl guge, begin runding the piece again acrss the face f the blank. Be careful t take small cuts and maintain the parallel face. Again, wrk slwly until yu have turned the piece rund t the spacer. Use a caliper and check t make sure the diameter is the same at bth ends. The intent is get the fur facets f the bttm f the bwl as even as pssible. Sand nw if necessary.

8 Step Three Cutting the Blank In rder t turn the tp f the bwl(s) yu will need t separate them. The easiest way is using the bandsaw, hwever nw yu have a smewhat rund and unstable piece. Cut a piece f ¾" plywd t apprximately 12" lng x 8" wide. Cut a 4" wide x 8" lng slt ut f ne end f the plywd. Nw take tw f thse triangular pieces yu cut ff the blank earlier, and glue them t the plywd n either side f the slt with the blank wedged between them (dn't glue the blank). Placing the bwl blank in the slt, hld the blank n the sides (nt the end) and line up the centre line n the spacer bard with the bandsaw blade. Slwly cut the tw halves apart, by sliding the jig frward thrugh the blade.

9 Nw yu have tw bwl blanks! Step Fur Make the Jig t Hld the Blank in the Lathe Glue tgether tw layers f ½" plywd and allw t dry. Find the diagnal centre and drill a small pilt hle thrugh. Using a circle jig in the bandsaw, cut the plywd t 12" diameter. Centre and screw-munt the plywd t a faceplate. Turn the utside f the plywd rund and true. Remve frm the lathe. Layut lines fr the 2x4 crss pieces n the faceplate. Cut 2 2x4s slightly shrter that the actual diameter f yur plywd plate. Use a table saw t trim ff ne edge f each 2x4 t flatten. Lay ut and pre-drill pilt hles frm the back f the plywd int the 2x4s. Mark the psitin f each 2x4 s it may be screwed int the crrect place later. Lay ut the centre f the length f each piece, and n ne, mark 1½" width fr the crss piece.

10 Lay the pieces tgether with the flat edges facing away frm each ther, and mark a pint ¾" frm the edge between the tw pieces n the centre line (bth sides). Using a cmpass set t 3" radius, centre n the new pints and draw an arc n the ppsite piece. These will be the lines t cut ut. Using the bandsaw, cut ut the arcs. Cut the 1½" sectin ut f the centre f ne piece. Use a spindle sander t trim the curves s they fit well tgether.

11 Screw the 2x4s t the plywd plate. The jig is ready. Put the jig n the lathe and run at lw speed t check if it is running true. Apply masking tape t the back f the bwl in bth directins. Using a ht glue gun, apply tw glue beads n the inside f the curves sectins f the jig and firmly push the bwl blank int place. Try t line up the blank with the face f the jig as best yu can.

12 Step Five Turn the Face and the Inside f the Bwl Munt the jig in the lathe. Yu may wish t bring up the tailstck fr additinal supprt initially, but it will need t be remved later. Set lathe at lwest speed again and stand clear when turning n. Begin by truing the surface f the blank acrss the tp. Push cuts wrk best here s as nt t chip the edges. Start hllwing ut the inside with a bwl guge using push cuts. Remve the tailstck when necessary. Start bwl guge in neutral cutting angle and start the cut t get supprt fr the Bevel. Open the cutting angle as yu prgress the cut. Return the cutting angle t neutral as yu apprach the centre. Mve the guge in an arc pattern frm the rim, dwn t the centre. "Step" yur cuts t wrk yur way dwn the bwl. Stp peridically t check bwl depth. D final cut as a fine finishing cut using the guge r a rund nse scraper. Sand and apply finish t inside surface. (Step Six Reverse the Bwl and Establish the Ft) Remve the bwl frm the lathe and reverse it by munting in a jam chuck. Begin flattening ff the bttm f the bwl slightly t establish a small ft. Make the "ft" f the bwl slightly cncave t allw the bwl t sit prperly n a flat surface. Sand and apply finish.

13 A Few Pinters Things t Remember Safety First!!! Be sure wd is always securely held in the lathe. Check again! Spin the wd by hand first t check securement and tlrest psitin. Start Slw!!! Remember the ABCs (Anchr - Bevel - Cut) Take small cuts dn t be t aggressive. Cut dwnhill cut with wd fibers supprted. Bevel rubbing. Have Fun! SUGGESTED RESOURCES Assciatins AAW American Assciatin f Wdturners Bks Richard Raffan The Art f Turned Bwls Richard Raffan Turning Wd with Richard Raffan Mike Darlw The Fundamentals f Wdturning David Ellswrth Ellswrth n Wdturning Derek Hayes Wdturning Design Bb Stcksdale T Turn the Perfect Bwl Vides Jimmy Clewes Richard Raffan Mike Mahney David Ellswrth Lcal Clubs and Guilds Thames Valley Wdturners' Guild (Lndn) Glden Hrseshe Wdturners' Guild (Burlingtn) Grey-Bruce Wdturners' Guild (Kincardine) Simce Wdturners' Guild (Simce) Trnt Wdturners' Guild (Trnt) Wdturners' Guild f Ontari (Pickering)