Cutting Technique

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PORTER INLAY CUTTING TECHNIQUE

I have used a variety of tools and techniques to cut inlays using a regular jeweler's saw frame which I started out with and found out very quickly that it was far too slow for selling inlays to the custom shops and Craftsmen via a mail order business.  C.E. Ward was one of the first post-war Craftsmen to use a power driven scroll saw to cut inlays, however he used metal templates to transfer the pattern to the peghead and fingerboard like Gibson did which left much to be desired, but it was pretty close to the tolerances that Gibson used on their inlays.  CE Ward also used photocopies of tracings from original designs which duplicated the errors and cutting imperfections.  My method of transferring an accurate pattern via the double stick method is more time consuming but yields a greater degree of accuracy especially when you have multiple cut inlay patterns of the same design to choose from.  I purchased a Nikon F2AS SLR  35MM camera body and a Nikon Nikkor 55MM lenses for 1:1 capture of original inlay designs on slide media and it worked great.  Still have that ole clunker today which was replaced with a couple digital cameras. 

I have used the lapidary type rock saw with a diamond blade and pantograph type machines for cutting inlays and engraving but used the lapidary saw for straight or angular cuts such as strips, diamonds and squares.  Dusted diamond wire worked but was far too expensive in the 1970s for cutting inlays.  The down side to this technique; if you are sloppy and inlays are a noticeable variance from your cutting pattern, you will have excessive filler around the inlays as most of the pre-war Gibson stuff was!  The advantage of hand routing is that you can scribe and route to the actual piece of inlay that you have cut.  I had the advantage of having about twenty (20) complete inlay patterns of each pattern on hand and was able to choose an individual inlay piece that matched the space I cut out of the fingerboard and peghead with a high degree of precision.   With this single inlay pattern, I am sure I will have to do a little filing of the fingerboard unless I cut a little plus tolerance for the inlays but ebony wood does take and hide filler real well and hope I can still maintain very close tolerances.

I have used the Delta and Rockwell/Delta brand of scroll saws since late 1968 to cut inlays with.  There are other excellent brands of heavy duty scroll saws available but the small,  light duty hobby type are a no no! My preferred jewelers saw blade was Vigor brand made in Germany or Sweden, can't remember which but they are no longer available or at least none of the places I use to purchase them from has access to them.  I used the # 6 size width blade for cutting all the standard Gibson stock patterns except I used the # 4 size width blade for cutting the script Gibson name and other small logos.  Also, I used .040 thick mother of pearl for years and it simply cut like butter using the # 6 blade and later went to the .050 thick mother of pearl because the major suppliers mother of pearl blanks were prone to have a taper from the center outward and would get real thin toward the edge.  When I went to the .050 thick mother of pearl, the saw cutting time increased and blade life diminished as well.  When using the .050 thick mother of pearl, script names such as Gibson did not break as often though. 

Currently I am using  Laser Blades brand blades that are much smaller in width than what Gibson used in the pre-war days and using a # 4 blade which has a width of around .016 inches and manufactured and/or sold by Rio Grande, 7500 Bluewater Road NW, Albuquerque, NW  87121-1962 Telephone:  800-545-6566.  You can also get them from David Nichols at Custom Pearl Inlay, 177 Low Road, Malone, NY  12953  Telephone: 518-483-7685.  David Nichols in my opinion is at the top without equal when it comes to cutting inlays by hand!  I believe I could have given him a run for his money in the mid 1970s only on Gibson pre-war inlay designs but cannot hold a candle to him today!  His cutting experience and artistic work has far exceeded my own and I certainly give homage to him!  I have examples of his work for master patterns for custom box calls that are as near perfect as can be done!  

Note:  David Nichols uses the much smaller blades the 3/0 versus the size 3 blade and a hand powered jewelers saw frame!         

 

I have used the above Rockwell/Delta 24" scroll since around 1980 being the third one that I have owned.  John Bowles of Advance, NC purchased the first one I used for around 10 years and Jim Yarboro of Gun Barrel City, Texas purchased the second one I purchased from an auction sale in Morven, NC which had a broken motor and he replaced the motor.  The standard saw above came with a a four speed step pulley and I use it at a fairly high rate of speed....by looking at the pulley ratio, I don't think it is a one to one transfer of the 1725 rpm mother but may be on the too fast side if any.  In the "ole days", I had the legs of the scroll saw base secured to the floor to help absorb the vibrations and there are specialized materials to place on the base of the saw for the saw purpose but can't remember if I used any back then...so much for the CRS disease (can't remember sometimes) is the clean version.     

An essential item to use when cutting mother of pearl and abalone is to use a dust mask, preferably the dual canister type and have the saw small air blower tip positioned to where it will blow the dust away from you.  I made a modification to the above saw by putting an aluminum shield plate right below the lower chuck for the blade and it is right at the top of the hollow spindle that connects to the internal cam of the machine.  This keeps the pearl dust from getting between the bronze lower bushing which has a felt sleeve above it but it will help keep the abrasive pearl dust from getting between the shaft/spindle and bronze bushing.  The felt dust shield does a poor job and it will allow the pearl dust to wear the spindle which is a thin piece of hollow steel tubing in short order if you are cutting 40 hours or more a week.  Pixs below:

The above dust guard was made from a flat piece of aluminum about .060 inches in thickness with a hole drilled in the center that matched the diameter of the hollow steel spindle.  The rear corners of the aluminum guard were bent downward to keep from hitting the saw frame and the front was bent downward also.  It was secured in place by the self-centering chuck above it which screwed into the hollow spindle.  Also, a couple screws were used to keep the dust guard from vibrating or moving around while the saw was in usage.  One of the screws held a screw that attached to the self-centering blade chuck which can be seen in the last pix above on the right.  I drilled and tapped the left side of the self-centering chuck for the 8-32 tpi screw/bolt and locked it with a nut against the chuck.  The guard was further secured to the screw with another screw/nut and cable clamp.  A "jerry rig" but it worked.  

NOTE:  Chuck Erikson aka The Duke of Pearl has recently written a treatise about some of the myths about the dangers of working with inlays.  Click on this link to open the document in Microsoft Word .DOC file.

Click on this link to open the document in Adobe Acrobat .PDF file.

Another modification was to change the round table insert which had a large slot in it to one without anything and drilled a small hole  large enough to accept the blade; no more than 1/16 inch in diameter.  The more support you have directly under the material you are cutting,  yields less mother of pearl breakage; especially on very fragile designs and materials.

The camera flash washed out the detail in the above pix but you can see where I have drilled two holes in the insert over the years and after a few years of usage, the jewelers saw blade will "wallow" aka enlarge the hole to where you need to relocate the insert and drill another hole.  I just recently drilled a small hole in the above insert.  If you are using a hand powered jewelers saw frame, you need to do the same thing with the support means underneath the mother of pearl and again use a small hole and access slot. To decrease the probability of breaking an inlay while cutting, you can add a 1/4 inch thick piece of clear Plexiglas material to the underside of the "foot" and drill and countersink small screws securing them through a couple holes drilled in each leg of the horseshoe shaped foot.  Saw a small slot at least 1/16 inch wide allowing the blade to come through but in this case with a much larger supporting area of the foot.  I break more mother of pearl when the blade breaks and the broken blade hits the bottom of the inlay you are cutting driving the piece upward allowing the design to try and go through the large horseshoe opening of the foot.   

When I cut inlays in the late 60's through 1979 on a regular basis, I did not use any magnification but those days are long gone!  Grin if you must!  I now have to use a pair of progressive glasses with the help of a +2.5 magnification Opti-Visor to be able to cut inlays.  With the Opti-Visor or any type of magnification, you have a certain working distance that will remain in focus; the more magnification, the closer you have to get to your material.  

Now to the inlay cutting starting with the pix on the left.  I looked at the layout of the mother of pearl pattern and decided to start cutting from the upper right and work my way through the pattern.  This is necessary in order to keep from "painting or cutting yourself into a corner" so to speak.  Exactly where to start on the inlay comes from experience but you want to have the most fragile part of the pattern surrounded by as much mother of pearl as you can.  I try and start the cut at a place where the exit cut for the pattern will leave as little a burr as possible, however sometimes you have to start away from a good exit point which is a little more difficult to have your starting and ending saw cut meet perfectly.  Click on each thumbnail pix and see where I started and ended. 

Another important point, especially on Gibson type designs and on the above design, you have many examples where your saw blade will enter the pattern between specific design elements and there is no way to turn around and exit back out of the cut you just made without enlarging the saw cut.  On those cuts, you want the saw blade cut detail to have a clean stopping point into the design and the only way you can achieve this is by backing out of the cut and finding an area nearby in the unused design portion of the pattern that will allow you to make a saw cut into and enlarge the cut and then turn your material around 180 degrees and enter the saw cut you just made with the back of the saw blade butting against the cut you must made.  You then proceed to move forward and then continue your cutting, repeating this back cutting technique until you have your pattern cut.  Many patterns will allow you to simply turn around in the cut but most of the Gibson designs and the above pattern required such a back cutting technique.   Words and pixs simply doesn't adequately describe what is taking place and a video clip would be much better.

The first inlay I cut from this pattern reflects that I haven't cut inlays in a good while of this type and you can see just a little of the black border outside the actual white inlay pattern.  As I continued to cut, the saw blade stayed next to the white pattern much closer but this is hand cutting inlays although you are using a machine to power the saw blade, it is still the hand to eye coordination that is making it possible.   The current blades running at the higher rate of speed doesn't last but a short while, maybe one small inlay design before it becomes dull requiring more pressure to be exerted which will distort the bottom of the pattern a little from the original top surface but most of the time is nil.  You will see a difference on the bottom of the 1/4 inch thick balsa wood reflecting such abnormal pressure used.  When a blade becomes too dull to cut or breaks, disengage the blade from the upper saw blade spring loaded plunger by loosing the adjustment thumbscrew and lifting the entire foot support upward and lock it in place with the thumbscrew.  Using the motor pulley, rotate the lower power shaft (plunger) of the jig saw until it is down as far as it will go and release the lower jaw chuck pressure by turning the thumbscrew counterclockwise and remove the jewelers saw blade.  Install a new blade making certain that the teeth are pointing downward and you do not have it so deep that the self-centering chuck will be gripping the cutting portion of the blade which is weaker and tighten the chuck by turning the thumbscrew clockwise.  Place the circular table insert back into the channel being sure that it is flush with the table top and no sawdust or debris is underneath it causing it to be "proud" above the table which can interfere with your cutting by hanging your substrate material against the elevated portion of the insert causing mother of pearl breakage and/or saw blade breakage.  Insert the saw blade back into your mother of pearl substrate material and slowly lower the pressure foot onto the material.  Rotate the motor pulley and cam the blade upward as far as it will go and lower the upper spring plunger tube downward and center the jewelers saw blade in the chuck and tighten the thumbscrew securing the blade.  Remember, adjust the foot pressure where it just barely contacts the mother of pearl/substrate material.  If it is adjusted too high, the material will make a "flopping" sound and if it is too tight, you run the risk of breaking a very delicate inlay by putting it into a bind.

The above pixs show myself working my way cutting each inlay design.  With the current blades, the process is very slow due to their cutting ability not lasting very long and/or breaking too soon.  The cut designs are looking much cleaner as I am staying with the pattern much closer getting cutting confidence built back up and not afraid to aggressively engage the design! 

The left pix shows nothing but scrap material from the first mother of pearl substrate layout.  The second pix from the left, I choose to start cutting my script Porter logo and started on the left of the pattern and worked around until I got to the lower portion of the letter P.  I then cut from the left side; tail of the letter R and finished up at the lower portion of the letter P.  This design similar to the script Gibson logo has open areas of mother of pearl that is left more or less hanging such as the letter E and the letter O which will break if you are not very careful.  I haven't cut a script Porter since the year 2000 and I could have cut it from another direction...so much for memory fading.....grin if you must.   A much safer approach would have been to drill a small hole into the center of the letter O and cut the inside shape out first and proceed as mentioned above but I guess my confidence level was high enough to risk it!  You must be able to cut both clockwise and counterclockwise as dictated by the pattern and the complexity of the design.  Also, one portion of the base of the flowerpot design in the peghead required drilling a small hole through the mother of pearl blank and the balsa wood substrate material since the cuts were inside the design and not able to access by the standard method and had to thread the jewelers saw blade at least three times in that design piece alone.  Pix on the right is the cut mother of pearl pattern with the paper pattern still double stick taped to the mother of pearl which is best to remove before inlaying and gives a better view of any detail that needs to be corrected such as burrs or cuts that are way outside of being symmetrical that may be corrected at the risk of breaking the inlay.  The same basic technique as far as maneuvering the mother of pearl material into the saw blade and back cutting works the same when using the hand powered jewelers saw frame,  You need to control the speed of your saw blade especially in tight turns when using the hand powered jewelers saw frame and the difference with the scroll saw,  you learn to control the speed and pressure that you are feeding the material into the saw blade and don't have the luxury of controlling the saw blade speed although you could put an auxiliary speed foot controlled device on your scroll saw if you really felt a need for it. 

 

It takes a very light touch to remove the double stick patterns from the precut mother of pearl inlays without breaking the inlay.  I use a very thin X-Acto knife blade and grip the inlay piece with as much support from the fingers as possible and very gingerly start at one side and only lift the tape and pattern from the inlay to get it started and try and peel and roll if off the design.  After the cutting pattern is removed from the inlays, inspect each piece for any exit burr that needs removing and/or any inlay that needs correcting to make it more symmetrical.  I used a small 1 inch diameter Dremel abrasive cutting disk for straight de-burring and on outside contours.  I used the tool and die makers files aka needle files for inside de-burring which this kit has an assortment of different shapes but missing about half them and the rest are ready to be trashed due to being in use for 41 years off and on....talk about being frugal;....grin if you must!.

I used a total of 38 # 4 jewelers saw blades to cut the above pattern which is more than twice or more what it should have taken.  I owe this to the quality of the blades and the user's cutting skills not up to full potential.  If you don't use it, you loose it! 

In closing this segment out, it took the entire afternoon of cutting, etc, off and on and about 3/4 of the way through the cutting, I realized that I didn't need the Opti-Visor and with just my standard progressive glasses, I cut to the edge of the pattern as good as with the Opti-Visor and was able to get more eye relief and sit with better posture while cutting which was much more comfortable.  It is important to have a bar type padded stool to sit on whereby you are high above the scroll saw  table enabling you to get a better and less distorted view of the cutting process.  The stool that I have is much too low and you cannot get the best view while cutting the pattern from a lower view or position at the scroll saw table.

Before cutting the peghead and fingerboard for the inlays, I plan to order size # 6 jewelers saw blades for this project which is a few thousands thicker and should have a little less breakage and get the proper height bar stool/chair.  The size # 6 blade will definitely not work for a very delicate design such as a Martin script logo, etc.

Following pix of a few loose Gibson "Flying Eagle" mother of pearl inlays that I found in my Kennedy machinists tool box dating back to the mid 1970s. I don't have a clue as to why I would have saved them and I gauged the width of the saw cuts and they were between .019 to .020 inches in width and I will guess around .0196 since the .019 gauge was a little loose in the slots and the .020 would only go into one of the cuts the full depth.  If one is to replicate the pre-war Gibson inlay designs or designs that have that type of boldness with the square cuts of the saw blade terminating into the design,  it is imperative that you use at least  a saw blade close to .020 inches in width which gives Gibson inlays their uniqueness and most of their designs require a cut-back into the material with the square cut versus a smaller diameter cut or a cut produced by a round cutting tool/bit. 

With this enlargement of the inlays, you can clearly see the saw cuts going into the design and terminating with a square or stop cut and you are unable to actually turn the saw blade around or should say turn your material around because your saw blade remains in the same basic position whether it is hand powered or machine powered.  To reiterate,  on those cuts, you want the saw blade cut detail to have a clean stopping point into the design and the only way you can achieve this is by backing out of the cut and finding an area nearby in the unused design portion of the pattern that will allow you to make a saw cut into and enlarge the cut and then turn your material around 180 degrees and enter the saw cut you just made with the back of the saw blade butting against the cut you must made.  You then proceed to move forward and then continue your cutting, repeating this back cutting technique until you have your pattern cut.  This procedure will not seem clear until you actually start cutting a design with a jewelers saw blade. 

The above pix enlargement shows the essence of the back cutting technique, whereas the saw cut was made into the design behind the saw blade and what you are looking at is the material being brought into the cut just made with the back of the saw blade (non-cutting portion of the blade) about to go into the cut just made and then continue the cutting design on the left of the saw blade.

It is very easy to understand why the CNC routers are heavily used in the pearl cutting and inlaying business today,  reducing not only the manual labor, cutting experience required, and those machines do not take coffee breaks and ask for vacation and holidays off, whereby producing  a consistent product governed by the programmers ability and whatever cutter limitation is imposed.  New technology in cutter design and materials has made it feasible to own and use CNC routers for inlays.

I lucked out today and did not break a single piece of mother of pearl for my Flaming Claw inlay pattern and hope the inlaying will go as smooth!  Bill aka Mickey Porter 02-28-10

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