Infinity markets a 2" bit with 4 carbide faces.
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Nick Offerman's quick review in Fine Woodworking:
Mega Dado and Planer Bit - FineWoodworking
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Pin Routers: The Old-School Production Workhorses
- Thread starter Bruce Johnson
- Start date
Infinity markets a 2" bit with 4 carbide faces.
Invalid Link Removed
Nick Offerman's quick review in Fine Woodworking:
Mega Dado and Planer Bit - FineWoodworking
I like it! I might have to get one of those for the big green monster. Not cheap, but it would quickly pay off in time savings.
I don't think you'd want to run that in a hand held router.
It's been a while! I've had a bunch of interruptions in my life, and haven't had much time to play with my big green pin router.
But today, we used it for its first real productive job since I took ownership of it, and moved it into my shop. Over in the Hardware Repair & Setup section, there's a thread about repairing the truss rods in two nice Pedulla basses. My buddy Luthier Randy Robinson and I used the the big green pin router to mill the ebony fingerboards off of these two Pedullas, using a sliding holding fixture on the table. You can read the details of the surgery on that thread:
Scary Repairs: Two Pedullas With Broken Truss Rods
It was great to run the machine and gain some experience with it. It made the job easy. I ran it at the slower speed, 10,000 rpm, and it was smooth and not very noisy at all. We weren't wearing ear protection and were talking over it easily.
Coming up, I'm going to be machining up a micrometer-like attachment for the turret depth stop, to allow me to quickly set depths of cut in 1/64" increments. Plus I'm going to build a floating clear plexi shroud around the spindle, as a guard and scoop for a dust collector.
I've got a lot of plans for this machine.
But today, we used it for its first real productive job since I took ownership of it, and moved it into my shop. Over in the Hardware Repair & Setup section, there's a thread about repairing the truss rods in two nice Pedulla basses. My buddy Luthier Randy Robinson and I used the the big green pin router to mill the ebony fingerboards off of these two Pedullas, using a sliding holding fixture on the table. You can read the details of the surgery on that thread:
Scary Repairs: Two Pedullas With Broken Truss Rods
It was great to run the machine and gain some experience with it. It made the job easy. I ran it at the slower speed, 10,000 rpm, and it was smooth and not very noisy at all. We weren't wearing ear protection and were talking over it easily.
Coming up, I'm going to be machining up a micrometer-like attachment for the turret depth stop, to allow me to quickly set depths of cut in 1/64" increments. Plus I'm going to build a floating clear plexi shroud around the spindle, as a guard and scoop for a dust collector.
I've got a lot of plans for this machine.
Randy came over and borrowed the big green pin router again this afternoon. For this job, he needed to re-shape the pickup openings on a carved top set-neck guitar. He had a routing template for the pickup openings, but it would have been tricky to attach it onto the carved top, and do the trimming with a hand-held router.
So, he mounted the template on the back of the body, on some standoff blocks, with double-stick tape. We set up the machine with a 1/4" router bit and a 1/4" pin. Then he used the pedal and turret depth stop to roughly set the cutter depth. Then lowered the cutter, with the spindle shut off, to check the alignment of the template on the body. Then he fired it up and trimmed out the two pockets in two depth passes. It worked very well, and didn't really take very long.
We're learning more about how to use this amazing machine. With some bits of tooling and fixtures, it can even be useful for quick one-off jobs like this.
So, he mounted the template on the back of the body, on some standoff blocks, with double-stick tape. We set up the machine with a 1/4" router bit and a 1/4" pin. Then he used the pedal and turret depth stop to roughly set the cutter depth. Then lowered the cutter, with the spindle shut off, to check the alignment of the template on the body. Then he fired it up and trimmed out the two pockets in two depth passes. It worked very well, and didn't really take very long.
We're learning more about how to use this amazing machine. With some bits of tooling and fixtures, it can even be useful for quick one-off jobs like this.
An update at last! It's been a long slow year, recovering from my heart valve installation. But I'm finally getting back to work in my shop more or less full time, including working on my machines!
I have big plans for my big green pin router. I want to get it fully into my production process, using it to do most of the routing of the bodies for my Scroll Basses. I'm starting on the tooling for my upcoming AMB-2M model, and I'll be making all the body tooling so the operations can be done on the pin router. But they also can be done with my bench routers, if I choose. We're also going to be tooling up so Keith can do the bodies for his guitars.
The first thing I've done is make up an adjustable guard foot thing that surrounds the spindle. The main purpose is safety. I don't want any of us to lose any fingers on this machine. A simple frame cage that blocks your hand from getting into the spinning parts. The whole assembly adjusts up and down about 4", and is locked by those four wingnuts.
I was originally going to put clear Lexan across the front, but I don't like how it can get covered with dust sticking to it. I decided to try making the front shield from wire cloth. I think that will work well. I need to be able to see what the cutter is doing. Here, the spindle is retracted all the way up. It will normally be cutting just below the bottom of the shoe. I'll usually adjust the height of the shoe to about 1/8" above the top of the sliding fixture.
The other purpose of this rig is chip collection. I built in an angled nozzle that is aimed right at where the cutting is happening. The 2 1/2" hose from my smaller dust collector will plug in there. I'm thinking that a smaller hose with higher suction and air velocity will work better than a big 4" hose. We'll see how it works.
The front screen pops off easily for changing bits or dialing in depth settings.
Speaking of depth settings, I machined up an adjustable upper stop. The lower section threads on a 3/8-16 bolt in the center. Being 16 tpi thread, one full turn of the lower section raises the spindle 1/16". A quarter turn is 1/64". I can now fine tune the depth of cut on the fly, while working toward a set Zero. I also set up the rotary depth stop in 1/4" increments. The long one is set to lock the spindle in the full up position, as you see here.
I may eventually machine up a new rotary stop wheel which is just fixed 1/8" increments. That would probably be the handiest arrangement.
I'll be starting on the first pin router fixtures in the next few days. I'm eager to get this fine old machine back in service, pumping out Scroll Basses!
I have big plans for my big green pin router. I want to get it fully into my production process, using it to do most of the routing of the bodies for my Scroll Basses. I'm starting on the tooling for my upcoming AMB-2M model, and I'll be making all the body tooling so the operations can be done on the pin router. But they also can be done with my bench routers, if I choose. We're also going to be tooling up so Keith can do the bodies for his guitars.
The first thing I've done is make up an adjustable guard foot thing that surrounds the spindle. The main purpose is safety. I don't want any of us to lose any fingers on this machine. A simple frame cage that blocks your hand from getting into the spinning parts. The whole assembly adjusts up and down about 4", and is locked by those four wingnuts.
I was originally going to put clear Lexan across the front, but I don't like how it can get covered with dust sticking to it. I decided to try making the front shield from wire cloth. I think that will work well. I need to be able to see what the cutter is doing. Here, the spindle is retracted all the way up. It will normally be cutting just below the bottom of the shoe. I'll usually adjust the height of the shoe to about 1/8" above the top of the sliding fixture.
The other purpose of this rig is chip collection. I built in an angled nozzle that is aimed right at where the cutting is happening. The 2 1/2" hose from my smaller dust collector will plug in there. I'm thinking that a smaller hose with higher suction and air velocity will work better than a big 4" hose. We'll see how it works.
The front screen pops off easily for changing bits or dialing in depth settings.
Speaking of depth settings, I machined up an adjustable upper stop. The lower section threads on a 3/8-16 bolt in the center. Being 16 tpi thread, one full turn of the lower section raises the spindle 1/16". A quarter turn is 1/64". I can now fine tune the depth of cut on the fly, while working toward a set Zero. I also set up the rotary depth stop in 1/4" increments. The long one is set to lock the spindle in the full up position, as you see here.
I may eventually machine up a new rotary stop wheel which is just fixed 1/8" increments. That would probably be the handiest arrangement.
I'll be starting on the first pin router fixtures in the next few days. I'm eager to get this fine old machine back in service, pumping out Scroll Basses!
I'm steadily working on the big green pin router, making improvements on it to improve the safety and productivity.
Here are the newest mods: I made up an aluminum rotary depth stop turret to replace the cast iron one with the adjustable screws.
The rotary depth stop wheel is 12 steps, increasing in height in exact 1/8" increments. The lowest step is "0", and then +1/8", +1/4", +3/8" etc, up to + 1 3/8". I machined it from 3/4" thick aluminum plate, set up on the rotary table on my milling machine. The steps are pretty accurate, probably +/- 0.002". I drew it out first in Qcad, made a full size pattern to trace onto the aluminum, and rough bandsawed it out.
While it was on the rotary table, I drilled that circle of spots every 30 degrees. That sheet metal bracket has a punched dimple that clicks in the holes. So the wheel turns easily and clicks into the 12 positions.
I added this rotary depth stop for speed in operation. For example, when I'm routing all the chambers on the inside of the top and back of a body, the chambers don't get routed to the same depth. With this rig, I set the wheel to "0" and adjust the table up to touch a gauge block that matches the deepest of the chambers.
Now, I can make one template that has all of the chambers, that goes into the sliding fixture for the pin router. I'll mark all the chambers' depths in relation to the "0" setting; +1/8", +1/4", etc. I've designed my instruments so that almost all of the pockets are in fractional 1/8" increments in depth. So, I can rout them all right in a row, in steps of cutting depth down to the final depth, by just hitting the pedal to raise the spindle and clicking the wheel.
If I need finer increments of depth, the stop is threaded and screws down. One turn equals 1/16", and I marked graduation lines for 1/64". And this can be done with one hand while the machine is running.
The aluminum mechanism up above is an upper lock for the spindle, for safety! The whole spindle and motor drive assembly is heavy, and it raises up and down with two pneumatic cylinders. A foot pedal valve on the floor applies and releases the air. One of the scary things of this machine is that, if the air pressure gets a little low, or you accidently bump the pedal, the spindle can suddenly drop down! Quite frightening, if it's running, and you are maneuvering a workpiece underneath it. Also, even after it's all shut off and sitting there quietly, the spindle will slowly sink down as the air leaks down.
I came up with this block and lever to lock the spindle in the upper position. Push the pedal to raise it up all the way, swing the lever over to the left, and it blocks the path so the spindle cannot lower down, no matter what.
When I'm ready to rout, tap the pedal on the heel to lift the spindle up a bit. Swing the lock lever off to the right. Tap the toe of the pedal to bring the spindle down against the depth stop wheel.
I'm showing you these mods to get you thinking about your own machines. It's not that hard to add parts to improve the safety and increase your productivity. Think about how you use your machine, what operations scare you, and what operations waste time. What gauges and tools can you make that will speed up the setup and increase the accuracy?
I'm about to start building the special sliding fixtures and templates to go with this big monster machine. I'm primarily setting up this machine to make bodies; for my own Scroll Basses and for several fellow Luthiers.
My other big project this year is a special neck shaping machine. I'll write a separate thread on it as it comes together.
Here are the newest mods: I made up an aluminum rotary depth stop turret to replace the cast iron one with the adjustable screws.
The rotary depth stop wheel is 12 steps, increasing in height in exact 1/8" increments. The lowest step is "0", and then +1/8", +1/4", +3/8" etc, up to + 1 3/8". I machined it from 3/4" thick aluminum plate, set up on the rotary table on my milling machine. The steps are pretty accurate, probably +/- 0.002". I drew it out first in Qcad, made a full size pattern to trace onto the aluminum, and rough bandsawed it out.
While it was on the rotary table, I drilled that circle of spots every 30 degrees. That sheet metal bracket has a punched dimple that clicks in the holes. So the wheel turns easily and clicks into the 12 positions.
I added this rotary depth stop for speed in operation. For example, when I'm routing all the chambers on the inside of the top and back of a body, the chambers don't get routed to the same depth. With this rig, I set the wheel to "0" and adjust the table up to touch a gauge block that matches the deepest of the chambers.
Now, I can make one template that has all of the chambers, that goes into the sliding fixture for the pin router. I'll mark all the chambers' depths in relation to the "0" setting; +1/8", +1/4", etc. I've designed my instruments so that almost all of the pockets are in fractional 1/8" increments in depth. So, I can rout them all right in a row, in steps of cutting depth down to the final depth, by just hitting the pedal to raise the spindle and clicking the wheel.
If I need finer increments of depth, the stop is threaded and screws down. One turn equals 1/16", and I marked graduation lines for 1/64". And this can be done with one hand while the machine is running.
The aluminum mechanism up above is an upper lock for the spindle, for safety! The whole spindle and motor drive assembly is heavy, and it raises up and down with two pneumatic cylinders. A foot pedal valve on the floor applies and releases the air. One of the scary things of this machine is that, if the air pressure gets a little low, or you accidently bump the pedal, the spindle can suddenly drop down! Quite frightening, if it's running, and you are maneuvering a workpiece underneath it. Also, even after it's all shut off and sitting there quietly, the spindle will slowly sink down as the air leaks down.
I came up with this block and lever to lock the spindle in the upper position. Push the pedal to raise it up all the way, swing the lever over to the left, and it blocks the path so the spindle cannot lower down, no matter what.
When I'm ready to rout, tap the pedal on the heel to lift the spindle up a bit. Swing the lock lever off to the right. Tap the toe of the pedal to bring the spindle down against the depth stop wheel.
I'm showing you these mods to get you thinking about your own machines. It's not that hard to add parts to improve the safety and increase your productivity. Think about how you use your machine, what operations scare you, and what operations waste time. What gauges and tools can you make that will speed up the setup and increase the accuracy?
I'm about to start building the special sliding fixtures and templates to go with this big monster machine. I'm primarily setting up this machine to make bodies; for my own Scroll Basses and for several fellow Luthiers.
My other big project this year is a special neck shaping machine. I'll write a separate thread on it as it comes together.
I'm finally getting to building the first set of real tooling for the big green pin router! This is a set of templates and routing fixtures for making the bodies for a new model Scroll Bass. I've been making the AMB-2 model Scroll Bass since 2012, and now I'm introducing a new slightly smaller 32" scale version called the AMB-2M (for Medium Scale). As compared to my standard (34 1/4" scale) AMB-2, the AMB-2M's neck is obviously shorter. But I'm also reducing the size of the body, shrinking it down proportionally by 9.1%. This means that I have to make up an entirely new set of tooling to make the bodies. Patterns, routing templates, holding fixtures. Almost none of the standard AMB-2 patterns would line up.
Shrinking it down was actually fairly easy to do in the computer. I use a simple 2D CAD program called Qcad. I had the standard AMB-2 all drawn up. I made a copy of all those layers, and got to work on the math of making it 32" scale. Once I worked out how much length I needed to take out of the body, from the neck heel to the bridge line, I established how much I needed to shrink the body; 9.1%. I set the back edge of the neck heel as the zero point, and used the Scale function to shrink most of the lines and polylines proportionally about that point, by 9.1%. However, the hardware doesn't shrink. The cavities and mounting hole patterns for the pickup, bridge, tailpiece and controls get moved to new locations, but not reduced in size. Some small changes to the contours of the internal chambering and openings.
The engineering is all done. I have the AMB-2M body all drawn out in Qcad. The hardware and mounting holes are accurately positioned and dimensioned. The curved shapes are all roughed in with segmented polylines.
I build my Scroll Bass bodies as a top and back, with extensive routing done inside the top and back before they get glued together. It starts as a matched set of four boards, all cut from one single walnut board. Here are two body sets, matched and arranged, ready to glue together.
Gluing the pairs of boards together with epoxy in the stack fixture. These become tops and backs.
You've probably seen this rig in the Router Planing Fixtures thread. I use it to cut both surfaces of each top and back to flat, and reduce them to 0.700" thickness. Note that the boards are held down into the fixture by four machine screws, in holes that are pre-drilled in the tops and backs. More on that coming up. Also, I'm doing a major rework and upgrade on this fixture. When it's done, I'll show it on the Router Planing Fixtures thread.
This is how I've been cutting all the internal cavities and chambers for all these years: Collar Routing. The router base has an aluminum sleeve collar that surrounds the bit, and the collar rides around in the opening in an MDF template. The openings in the template are "offset", that is, cut oversize by an amount based on the diameter of the collar vs the diameter of the bit. The template is located on the walnut blank by two small 1/8" steel dowel pins that plug into reference holes drilled in the walnut. Those two reference holes get used all through the process of building the body. They keep everything lined up, including gluing the top and back together.
Here's a walnut back with most of the internal routing completed. Some of the pockets are routed to different depths, and the insides of the F-holes are routed using a large cove (half round) bit. The smaller pockets are all done with a straight 1/2" router bit. You can see the small pilot holes down the center. They are only drilled 1/2" deep into the back, but all the way through the top. You can also see the four countersunk holes that hold the walnut into the router planing fixture.
That's the process I've been using for 23 years on my Scroll Bass bodies. But now I've got the Big Green Pin Router sitting here, ready to start chewing wood! For the new AMB-2M, I'm going to try doing most of the above process using the pin router, instead of the collar router. This will require a different way of making the templates, plus some special holding fixtures.
I'll show the process of making up that tooling in the next posts.
Shrinking it down was actually fairly easy to do in the computer. I use a simple 2D CAD program called Qcad. I had the standard AMB-2 all drawn up. I made a copy of all those layers, and got to work on the math of making it 32" scale. Once I worked out how much length I needed to take out of the body, from the neck heel to the bridge line, I established how much I needed to shrink the body; 9.1%. I set the back edge of the neck heel as the zero point, and used the Scale function to shrink most of the lines and polylines proportionally about that point, by 9.1%. However, the hardware doesn't shrink. The cavities and mounting hole patterns for the pickup, bridge, tailpiece and controls get moved to new locations, but not reduced in size. Some small changes to the contours of the internal chambering and openings.
The engineering is all done. I have the AMB-2M body all drawn out in Qcad. The hardware and mounting holes are accurately positioned and dimensioned. The curved shapes are all roughed in with segmented polylines.
I build my Scroll Bass bodies as a top and back, with extensive routing done inside the top and back before they get glued together. It starts as a matched set of four boards, all cut from one single walnut board. Here are two body sets, matched and arranged, ready to glue together.
Gluing the pairs of boards together with epoxy in the stack fixture. These become tops and backs.
You've probably seen this rig in the Router Planing Fixtures thread. I use it to cut both surfaces of each top and back to flat, and reduce them to 0.700" thickness. Note that the boards are held down into the fixture by four machine screws, in holes that are pre-drilled in the tops and backs. More on that coming up. Also, I'm doing a major rework and upgrade on this fixture. When it's done, I'll show it on the Router Planing Fixtures thread.
This is how I've been cutting all the internal cavities and chambers for all these years: Collar Routing. The router base has an aluminum sleeve collar that surrounds the bit, and the collar rides around in the opening in an MDF template. The openings in the template are "offset", that is, cut oversize by an amount based on the diameter of the collar vs the diameter of the bit. The template is located on the walnut blank by two small 1/8" steel dowel pins that plug into reference holes drilled in the walnut. Those two reference holes get used all through the process of building the body. They keep everything lined up, including gluing the top and back together.
Here's a walnut back with most of the internal routing completed. Some of the pockets are routed to different depths, and the insides of the F-holes are routed using a large cove (half round) bit. The smaller pockets are all done with a straight 1/2" router bit. You can see the small pilot holes down the center. They are only drilled 1/2" deep into the back, but all the way through the top. You can also see the four countersunk holes that hold the walnut into the router planing fixture.
That's the process I've been using for 23 years on my Scroll Bass bodies. But now I've got the Big Green Pin Router sitting here, ready to start chewing wood! For the new AMB-2M, I'm going to try doing most of the above process using the pin router, instead of the collar router. This will require a different way of making the templates, plus some special holding fixtures.
I'll show the process of making up that tooling in the next posts.
Okay, getting into the new tooling:
The first, and most important thing to make is the Master Template. It also takes the most time to make, because it's mostly hand cut (with some power tools!). That is, the shapes and dimensions are all cut to pencil lines, measuring carefully.
Here's the original Master Template for my Scroll Bass bodies. It's a close match to the 1960's Ampeg Scroll Basses in dimensions and shape. I made it back in 1997, and used it for all the Scroll Basses I've made up until now. This picture is from about 2006.
The Master Template is made from 3/4" MDF (the heavy kind), and it has two steel drill guide bushings pressed in along the centerline. These bushings are used to drill the all-important reference holes. Everything else references from those two holes. The outside of the Master Template is the final perimeter shape of the body, accurately in position in relation to the reference holes. The shape and the reference holes are all drawn into the CAD drawing, along with the other routed chambers and hardware. The design and dimensional work is done before making the Master Template.
This old Master Template also has the cutouts for the F-holes cut through it. Again, accurately positioned and shaped to match the CAD layout. You'll see that the new AMB-2M Master Template will also have accurate cutouts of all the internal chambers. And, while I'm at it, I'm going to make up a new full-size AMB-2 Master Template with upgraded features to go with the pin routing.
The Master Template is really a 3D solid reference "drawing". All of the other tooling is derived from it, and everything is checked against it. It makes sure that everything lines up and fits together. It has three main jobs in my process:
Through the drawing, I carefully centerpunch the locations of the two reference holes.
While keeping the drawing taped down, I lift up the corners and slide a sheet of old-fashioned carbon paper underneath. One quarter at a time. Then I use a pencil and draw around the perimeter and F-holes on the drawing, which transfers the lines down onto the MDF.
And there's resulting layout of the Master Template on the MDF blank.
The first, and most important thing to make is the Master Template. It also takes the most time to make, because it's mostly hand cut (with some power tools!). That is, the shapes and dimensions are all cut to pencil lines, measuring carefully.
Here's the original Master Template for my Scroll Bass bodies. It's a close match to the 1960's Ampeg Scroll Basses in dimensions and shape. I made it back in 1997, and used it for all the Scroll Basses I've made up until now. This picture is from about 2006.
The Master Template is made from 3/4" MDF (the heavy kind), and it has two steel drill guide bushings pressed in along the centerline. These bushings are used to drill the all-important reference holes. Everything else references from those two holes. The outside of the Master Template is the final perimeter shape of the body, accurately in position in relation to the reference holes. The shape and the reference holes are all drawn into the CAD drawing, along with the other routed chambers and hardware. The design and dimensional work is done before making the Master Template.
This old Master Template also has the cutouts for the F-holes cut through it. Again, accurately positioned and shaped to match the CAD layout. You'll see that the new AMB-2M Master Template will also have accurate cutouts of all the internal chambers. And, while I'm at it, I'm going to make up a new full-size AMB-2 Master Template with upgraded features to go with the pin routing.
The Master Template is really a 3D solid reference "drawing". All of the other tooling is derived from it, and everything is checked against it. It makes sure that everything lines up and fits together. It has three main jobs in my process:
- First, I use it as a layout template when making up the routing templates. I use it as a drill guide, drilling the reference holes down through the steel bushings. This makes sure that the guide pin holes in the templates are at the right spacing and location.
- Second, I use it as a temporary routing template, in the pin router, to make up the real routing templates.
- Third, I use it when making up every Scroll Bass body. I position it on the walnut top or back, lining up the shape in relation to the grain pattern and any flaws. I drill the reference holes, hold it in place with two steel pins, and pencil trace the outline onto the walnut. That's what's going on in the picture above.
Through the drawing, I carefully centerpunch the locations of the two reference holes.
While keeping the drawing taped down, I lift up the corners and slide a sheet of old-fashioned carbon paper underneath. One quarter at a time. Then I use a pencil and draw around the perimeter and F-holes on the drawing, which transfers the lines down onto the MDF.
And there's resulting layout of the Master Template on the MDF blank.
Continuing on making up the new Master Template:
The first thing is to install the steel drill guide bushings for the two reference holes. Here, I'm using 5/16" OD x 1/8" ID bushings. Drill guide bushings of this size are fairly expensive new, like $10 each. I had a stash of them that I bought years ago at a surplus store, but I've run out. So, in this case I just machined up some new ones from scratch from 5/16 steel bar stock in my trusty metal lathe.
I carefully drilled the holes in the MDF, slightly undersize, and pressed in the drill bushings.
Then over to the bandsaw to saw out the perimeter. Carefully, close to the line.
Over to the drill press to drill a bunch of 1/2" holes down through the F-hole openings.
Then I dragged this Ryobi Scrollsaw out of a dusty closet. A machine I don't use often, but sometimes it's really handy. I fitted it up with a chunk of 1/4" x 10tpi bandsaw blade stock and fed it down through the holes.
It did a nice job rough cutting the F-holes. Slower than a bandsaw, but I could steer it accurately.
Here's the rough cut AMB-2M Master Template sitting on top of the full size AMB-2 Master Template for comparison. It's 9.1% smaller.
The first thing is to install the steel drill guide bushings for the two reference holes. Here, I'm using 5/16" OD x 1/8" ID bushings. Drill guide bushings of this size are fairly expensive new, like $10 each. I had a stash of them that I bought years ago at a surplus store, but I've run out. So, in this case I just machined up some new ones from scratch from 5/16 steel bar stock in my trusty metal lathe.
I carefully drilled the holes in the MDF, slightly undersize, and pressed in the drill bushings.
Then over to the bandsaw to saw out the perimeter. Carefully, close to the line.
Over to the drill press to drill a bunch of 1/2" holes down through the F-hole openings.
Then I dragged this Ryobi Scrollsaw out of a dusty closet. A machine I don't use often, but sometimes it's really handy. I fitted it up with a chunk of 1/4" x 10tpi bandsaw blade stock and fed it down through the holes.
It did a nice job rough cutting the F-holes. Slower than a bandsaw, but I could steer it accurately.
Here's the rough cut AMB-2M Master Template sitting on top of the full size AMB-2 Master Template for comparison. It's 9.1% smaller.
Cleaning up the AMB-2M Master Template:
Another handy machine in my shop: an Oliver S-4 Die Filer from the 1950's. It's a power filing machine. The file that you clamp between the chucks reciprocates up and down, staying square to the table. Die Filers are cool machines. I have 5 of them. Just the thing for cleaning up the inside walls of the F-hole cutouts.
Then over to the vise to true up the perimeter and the F-holes with hand files and sanding blocks. This is where I have to spend some time making sure all the curved lines are smooth. No dips or bumps. These curves are the final shape which will be copied to the router templates, and then to the actual bass bodies.
As I was making up this new Master Template, I realized that I should also add in all the internal chambers. It would make it simpler to make up the routing templates. I couldn't on the old Master Template because they were all done by collar routing. Their templates all had to be oversize/offset. Now with the pin routing, the templates will be actual size. So it makes sense to cut them into the new Master Template.
I put the drawing back on, this time holding with the two pins in the reference holes. Carbon paper underneath, draw the outlines....
And there's the layout. I use that piece of 1/2" dia aluminum rod to check the shapes. I'm going to be using a 1/2" bit in the pin router to cut all these chambers, so I need to make sure that the bit will fit into the corners.
A bunch more 1/2" holes.....
And some more quality time on the Ryobi Scrollsaw......
Rough sawn....
And the Die Filer.....
Cleaning up the openings with hand files.
And checking the fit with that 1/2" rod.
Another handy machine in my shop: an Oliver S-4 Die Filer from the 1950's. It's a power filing machine. The file that you clamp between the chucks reciprocates up and down, staying square to the table. Die Filers are cool machines. I have 5 of them. Just the thing for cleaning up the inside walls of the F-hole cutouts.
Then over to the vise to true up the perimeter and the F-holes with hand files and sanding blocks. This is where I have to spend some time making sure all the curved lines are smooth. No dips or bumps. These curves are the final shape which will be copied to the router templates, and then to the actual bass bodies.
As I was making up this new Master Template, I realized that I should also add in all the internal chambers. It would make it simpler to make up the routing templates. I couldn't on the old Master Template because they were all done by collar routing. Their templates all had to be oversize/offset. Now with the pin routing, the templates will be actual size. So it makes sense to cut them into the new Master Template.
I put the drawing back on, this time holding with the two pins in the reference holes. Carbon paper underneath, draw the outlines....
And there's the layout. I use that piece of 1/2" dia aluminum rod to check the shapes. I'm going to be using a 1/2" bit in the pin router to cut all these chambers, so I need to make sure that the bit will fit into the corners.
A bunch more 1/2" holes.....
And some more quality time on the Ryobi Scrollsaw......
Rough sawn....
And the Die Filer.....
Cleaning up the openings with hand files.
And checking the fit with that 1/2" rod.
Yes, this pin router should be able to rout all these cavities and chambers in less than half the time it would take by collar routing. Two reasons: I'll be able to cut almost everything in a single template/fixture setup with nearly instant resetting of the depth stops. And this thing has 10 HP on the spindle! If my fixturing is solid enough, I should be able to rout these cavities in 1/2" or more depth per pass. Rather than 1/8"-1/4" per pass with the collar router.
Pin router vs CNC depends on what size class you are comparing. The pin router should be faster than a light-duty CNC machine that uses a regular router head. Same reason as above: Horsepower, rigid frame, depth of cut per pass. However, a Real CNC machine like Rob Allen's weighs 6000 lbs and has a 20 HP (!!) spindle. With really solid tooling, it'll beat the pin router. Same reasons. Horsepower matters. As long as you can hold onto the wood part!
That's a big part of what I'm doing now, designing and building the fixtures to be able to hold onto the walnut boards as I'm applying the big pin router to them. A lot of thought and care. As I'm testing them out, I'll be working my way up in how much depth of cut I can do per pass. 1/8", 1/4", 3/8", 1/2", ??? I may eventually be able to cut all these cavities in a single depth pass.
While I'm working on the Master Templates, here's another important piece of tooling that needed to be made: a Locating Pin Hole Drill Fixture.
As I mentioned above, a really important thing in making fixtures for pin routers is being able to accurately and tightly hold the walnut blank in the fixture. It has to lock into the exact position, and not move under heavy side loads. And, hopefully, it's quick to pop a finished blank out and pop the next one in.
I decided to design my tooling to use two 3/16" dia pins to locate the blanks in the fixtures. These pins are located in diagonally opposite corners of the blank, in the waste wood outside the perimeter of the body shape. Each walnut blank will need to have these two holes pre-drilled in it, in accurate position in relation to the body shape and the two small reference holes down the centerline.
That's the main function of this drill fixture. First I use the Master Template, as I described above, to decide the location of the body shape on the walnut blank. I use the Master Template to drill the small reference pin holes down the centerline. Then this Locating Pin Hole Drill Fixture plugs into those reference holes, and I use it to drill the two 3/16" holes in the outer corners. It has 3/16" ID steel drill bushings pressed in. Like most of the other tooling, it's made from heavy 3/4" MDF.
The red arrows show the bushings for drilling the locating pin holes.
There are six other drill guide bushings in a rectangular pattern. This fixture also has a second job. I also use it to drill the holes for the screws to hold the walnut blank down securely in the Router Planing Fixture. I've layed out this fixture so it will work with all of my Scroll Bass and SSB models. I was even careful to position the locating pins clear of where the horns will be on my upcoming Devil Bass model.
Tooling sets like this require a lot of long term thought. About half of my current Scroll Bass tooling has been in use for 25 years now. I hope these fixtures I'm building now will be good for 400+ Scroll basses over the next 20 years.
As I mentioned above, a really important thing in making fixtures for pin routers is being able to accurately and tightly hold the walnut blank in the fixture. It has to lock into the exact position, and not move under heavy side loads. And, hopefully, it's quick to pop a finished blank out and pop the next one in.
I decided to design my tooling to use two 3/16" dia pins to locate the blanks in the fixtures. These pins are located in diagonally opposite corners of the blank, in the waste wood outside the perimeter of the body shape. Each walnut blank will need to have these two holes pre-drilled in it, in accurate position in relation to the body shape and the two small reference holes down the centerline.
That's the main function of this drill fixture. First I use the Master Template, as I described above, to decide the location of the body shape on the walnut blank. I use the Master Template to drill the small reference pin holes down the centerline. Then this Locating Pin Hole Drill Fixture plugs into those reference holes, and I use it to drill the two 3/16" holes in the outer corners. It has 3/16" ID steel drill bushings pressed in. Like most of the other tooling, it's made from heavy 3/4" MDF.
The red arrows show the bushings for drilling the locating pin holes.
There are six other drill guide bushings in a rectangular pattern. This fixture also has a second job. I also use it to drill the holes for the screws to hold the walnut blank down securely in the Router Planing Fixture. I've layed out this fixture so it will work with all of my Scroll Bass and SSB models. I was even careful to position the locating pins clear of where the horns will be on my upcoming Devil Bass model.
Tooling sets like this require a lot of long term thought. About half of my current Scroll Bass tooling has been in use for 25 years now. I hope these fixtures I'm building now will be good for 400+ Scroll basses over the next 20 years.
Some more bits of tooling to help make up the routing templates:
Last night I used one of my handy metal lathes to machine up these two aluminum collars. They are 1/2" ID to slip over the 1/2" pin of the pin router. The larger one (sitting on the pin) is 1 1/2" OD, and the smaller one is 1" OD.
I'll use these as temporary adapters when I'm making up new routing templates for the pin router, copying from older templates which are offset for collar routing. For example, most of my collar routing templates are made to use a 1/2" bit with a 1" collar base. Now I can slip this new 1" collar over the pin to copy the shapes in the old template, quickly and accurately, but in actual size; no offset. A few of my old templates were made for a 1 1/2" collar base.
Last night I used one of my handy metal lathes to machine up these two aluminum collars. They are 1/2" ID to slip over the 1/2" pin of the pin router. The larger one (sitting on the pin) is 1 1/2" OD, and the smaller one is 1" OD.
I'll use these as temporary adapters when I'm making up new routing templates for the pin router, copying from older templates which are offset for collar routing. For example, most of my collar routing templates are made to use a 1/2" bit with a 1" collar base. Now I can slip this new 1" collar over the pin to copy the shapes in the old template, quickly and accurately, but in actual size; no offset. A few of my old templates were made for a 1 1/2" collar base.
Bruce, this is awesome! Thanks for sharing all the steps with us. Cheers, Bobo
Jazzdogg
Less barking, more wagging!
I had a "green monster" in my classroom at the college where I taught. It was under lock & key, and could not be used without direct supervision from a staff member qualified by the department chair, just like our shapers. All operators, including instructors who were qualified users, were required to run the machine with a "buddy" who could dial 9-1-1 and administer first aid until help arrived.
No one was ever allowed to hold a workpiece in their bare hands. In fact, we created fixtures that enabled users to keep their hands well away from the cutter at all times.
Plan for the worst that can happen, have a buddy double check all operations before the power is turned on, and never work alone.
Good luck!
