Pin Routers: The Old-School Production Workhorses

[Bruce Johnson]

Okay, with the templates done, I flipped the fixture over and mounted the Roscoe neck on the top side.

I locked it in place with five wood block cleats, lining it up carefully with the centerline and the inlay position lines.

Here's the 1/8" pin that I made up for the MGPR.....

And here's the 1/8" router bit. I set the depth by cranking the head down (shut off) until the bit touches the surface, then zeroing the pointer on the ruler. I took this picture with the guard off.

Starting the routing, with the wire cloth guard in place. Notice how the camera focuses on the guard. But when I'm focusing on the router bit, the guard is almost invisible.

Here's one of the oval cavities after cutting it 0.030" deep with the 1/8" bit. Note that it's got some fuzz around the outside.

The cavity is in the correct centered position. That pencil line is from an early rough layout.

Here's the process of pin routing the cavities. I did all 10 with the 1/8" bit first. That bit wouldn't get into the ends of the last 4 skinny ovals. I cut them all in two depth passes. Not really necessary, but I was being careful.

The pin routing goes quite fast. I did all 10 in about 12 minutes.

Then I switched over to the teeny little 1/16" bit. Which looks almost silly in this 2000lb machine. It's a brand new bit from Freud.

And there's the 1/16" pin that I made up......

Here's another look at the fuzziness left after cutting the cavity with the 1/8" bit.

But this is interesting; When I went back over each of the cavities with the 1/16" bit, it smoothed out the edges and trimmed off all the fuzz. I'm not sure why, but the little bit did a neater job.

I'm wondering if this could be a regular job for the LGPR, the little pin router? Keep it set up with a 1/16" bit, nearby. After running any routing job in the BGPR or MGPR, slide it over into the LGPR to quickly de-fuzz it.

The inlay cavities on the Roscoe are done! Overall, they came out nice and clean and accurate. I definitely like using the MGPR for cutting them.

This was a good R & D exercise. I'm learning more all the time about how to use these machines.

 

[MPU]

Does the laser give you clean perpendicular edges in 1/4" MDF?

I haven’t cut 6mm MDF but I’ve cut 6mm laser plywood and 6mm acrylic and the cut is very clean and perpendicular. With bearing guided router bit I can use the template and the offcut to make exact patches for covering pickup holes or similar. The fit is very tight, I have to tap the patch in place. That’s something like an inlay.
I have not cut MOP succesfully. It chipped in horizontal layers no matter how I adjusted the cut. The cut also bonds together and does not want to separate cleanly.

 

[MPU]

That pin routing is fast! Like always, routing is mostly making tempaltes and fixtures and the routing itself is fast.

 

[Bruce Johnson]

That pin routing is fast! Like always, routing is mostly making tempaltes and fixtures and the routing itself is fast.

Yeah, I think the ideal setup is a computer with Cad and a small CNC router to make all the templates. And then several pin routers, a shelf of fixtures, and a good reliable employee to make the basses. That would be efficient.

 

[Bruce Johnson]

And here's how the Roscoe inlays came out, if you are interested......

These inlays were really thin, ranging from 0.015" to 0.025" thick. I needed to make sure they went in just right, not too high or too deep. I used the Packing Tape Trick. I dabbed some West Systems epoxy into the cavity. Then stuck the inlay to a square of clear packing tape and gently inserted it into the cavity, sticking the tape to the fingerboard. The tape holds the inlay flush with the surface while the epoxy underneath cures.

There they are, all in place.

And there they are with the tape pulled off and the epoxy sanded off the surface. Most of them are really neat and tight fitting. The last couple of skinny ones have a few gaps at the ends. Several of them got broken during the removal, and I had to CA glue them back together. So they weren't perfect ellipses and didn't fit perfectly into the templates. But I'm happy with the job overall, and glad that I could save these old inlays. They are a nice looking design.

The story of this neck will now jump back over to its own thread, where Jeremy and I will finish it up.

 

[smcgov]

And here's how the Roscoe inlays came out, if you are interested......

View attachment 7067699

These inlays were really thin, ranging from 0.015" to 0.025" thick. I needed to make sure they went in just right, not too high or too deep. I used the Packing Tape Trick. I dabbed some West Systems epoxy into the cavity. Then stuck the inlay to a square of clear packing tape and gently inserted it into the cavity, sticking the tape to the fingerboard. The tape holds the inlay flush with the surface while the epoxy underneath cures.

View attachment 7067698

There they are, all in place.

View attachment 7067701


And there they are with the tape pulled off and the epoxy sanded off the surface. Most of them are really neat and tight fitting. The last couple of skinny ones have a few gaps at the ends. Several of them got broken during the removal, and I had to CA glue them back together. So they weren't perfect ellipses and didn't fit perfectly into the templates. But I'm happy with the job overall, and glad that I could save these old inlays. They are a nice looking design.

The story of this neck will now jump back over to its own thread, where Jeremy and I will finish it up.

I think this is an incredible transplant, was each inlay a different depth? how in the heck did you get them all flush?

 

[Matt Liebenau]

I think this is an incredible transplant, was each inlay a different depth? how in the heck did you get them all flush?

That’s where “the packing tape trick” comes in. Reread the paragraph under the first picture. The inlay route gets filled with West Syatems, the inlays get stuck to packing tape which then gets stuck to the fretboard and holds the inlays at fretboard level.

Fantastic stuff which I never would have thought of before reading Bruce’s post. Like most good tips, it’s obvious once you see it.

 

[Bruce Johnson]

I think this is an incredible transplant, was each inlay a different depth? how in the heck did you get them all flush?

Like Matt said, that's what the packing tape and the epoxy was all about. These "used" inlays were very thin and variable in thickness, because they had been previously installed and sanded flush with the fingerboard. So, I routed the cavities a little bit deeper than the thickest one and poured in some epoxy. Then the inlays were set in and held flush with the surface by the packing tape, as the bed of epoxy cured underneath them.

This wouldn't have worked with Titebond, and would have been tricky with CA glue. The epoxy is able to cure at full strength while filling a gap like that.

If this had been an installation of new inlays, I would have made the inlays from 1/16" (0.063") thick material. I would have routed the cavities 0.030"-0.040" deep. Pour in a small amount of epoxy, and just set the inlays in there. That would leave them sticking up 0.020"-0.030" above the surface. After the epoxy is cured, I'd file them down to flush with the surface. That's the normal way to put in inlays. And I'm sure that's how Roscoe installed these at the factory, many years ago.

 

[smcgov]

Like Matt said, that's what the packing tape and the epoxy was all about. These "used" inlays were very thin and variable in thickness, because they had been previously installed and sanded flush with the fingerboard. So, I routed the cavities a little bit deeper than the thickest one and poured in some epoxy. Then the inlays were set in and held flush with the surface by the packing tape, as the bed of epoxy cured underneath them.

This wouldn't have worked with Titebond, and would have been tricky with CA glue. The epoxy is able to cure at full strength while filling a gap like that.

If this had been an installation of new inlays, I would have made the inlays from 1/16" (0.063") thick material. I would have routed the cavities 0.030"-0.040" deep. Pour in a small amount of epoxy, and just set the inlays in there. That would leave them sticking up 0.020"-0.030" above the surface. After the epoxy is cured, I'd file them down to flush with the surface. That's the normal way to put in inlays.

i'm guessing had you put "too much" epoxy in the cavity and it had pushed out around the edges it could still have been sanded?

 

[Bruce Johnson]

i'm guessing had you put "too much" epoxy in the cavity and it had pushed out around the edges it could still have been sanded?

Well yeah, that's exactly what happened, intentionally. You can see how the excess epoxy squirted out around them under the tape. On the second one in particular, I had a little too much in there. But the epoxy squirt-out all sanded off easily enough. I used a flat file to take off the biggest lumps, and my Long Board with 120 grit paper to clean off the rest. Out at the heel end, the epoxy oozed into a couple of the fret slots. I scraped most of it out before it cured, but I'll go through those slots with a hand slotting saw to make sure they're cleaned out.

 

[smcgov]

Well yeah, that's exactly what happened, intentionally. You can see how the excess epoxy squirted out around them under the tape. On the second one in particular, I had a little too much in there. But the epoxy squirt-out all sanded off easily enough. I used a flat file to take off the biggest lumps, and my Long Board with 120 grit paper to clean off the rest. Out at the heel end, the epoxy oozed into a couple of the fret slots. I scraped most of it out before it cured, but I'll go through those slots with a hand slotting saw to make sure they're cleaned out.

amazing I bet there aren't too many guys who could pull this off at this level

 

[Bruce Johnson]

I made an upgrade to the MGPR (Medium Green Pin Router) tonight. Using it to do those inlays, it was the first time doing real precision work. Sitting down, somewhat hunched over it. I found that it was uncomfortable working the crank to raise and lower the router head.

Here's how it was:

I had mounted the ruler and pointer up high like that, almost at eye level when standing. It made it easier to read, but.........When sitting down, I kept hitting my right arm on it when trying to reach up and work the crank to adjust the depth.

So, I reworked it:

I cut down the brackets, moving the whole ruler and pointer assembly straight down by 6". This gets it out of the way of the crank. And it's still easy enough to read.

And I enlarged the crank wheel from 4" diameter to 8" diameter by adding a new 1/4" aluminum disk on top. This makes it easier to reach and makes it finer resolution of the depth adjustment.

These mods took about an hour in the Sunday night shift. Improving my machines to make them better is an ongoing process.

As I expected, the MGPR is turning out to be the machine for the precision work, mostly on necks. The BGPR is for hogging out chambers and cavities in larger parts, mostly bodies. The SPRP is for router-planing surfaces of blanks. The upcoming Neckster will be specifically for shaping the backs of necks. The little LGPR will be for small precision parts. Those will be my five pin routers.