Router Planing Fixtures

[83_Silberpfeil]

Thanks for providing your thoughts Bruce, always appreciated. I will make a run to HD today and level check. Indeed, they are overkill, strenghtwise --- but convenient enough, square/parallel two tubes, and to just bolt'm down to a 3/4 MDF and ready to go.

Yes, the center block is 1.25" thick. I think there's a 1.5" X 1.5" version of these tubes that will work for me. I do have lots of scraps here and there, so will need to check if I have any that are level/flat and thick enough.

Thanks again!

 

[83_Silberpfeil]

After further evaluating further, I've decided to take a different, less expensive approach. I've pulled out old 10" Skil table saw that's been sitting around for 2+ years, and cleaned it up and installed a new blade I had in the storage bin, and tested a few cuts. Nice and clean and straight/square.

So, I'm going to attempt to resaw the 8/4 mahog down to 1.25 using the table saw. The width of board is 5.75", and the table saw blade can cut a thickness of up to 3.5". Certainly I'm not going to attempt a 3.5" cut, but instead use the "flip end-over-end" approach and try to get away with raising saw blade to 3". Will take it slow and cut 1/2" depth at a time. Hopefully it will work, and only require sanding afterwards (and no further planing or jointng).

As an aside --- thinking thru this task got me to realize how valuable it would be to learn how to hand-plane, and do it well.

 

[Bruce Johnson]

After further evaluating further, I've decided to take a different, less expensive approach. I've pulled out old 10" Skil table saw that's been sitting around for 2+ years, and cleaned it up and installed a new blade I had in the storage bin, and tested a few cuts. Nice and clean and straight/square.

So, I'm going to attempt to resaw the 8/4 mahog down to 1.25 using the table saw. The width of board is 5.75", and the table saw blade can cut a thickness of up to 3.5". Certainly I'm not going to attempt a 3.5" cut, but instead use the "flip end-over-end" approach and try to get away with raising saw blade to 3". Will take it slow and cut 1/2" depth at a time. Hopefully it will work, and only require sanding afterwards (and no further planing or jointng).

As an aside --- thinking thru this task got me to realize how valuable it would be to learn how to hand-plane, and do it well.

You can use a tablesaw like that to thin down a board. The tricky part is making sure that the board stays flat and perpendicular against the fence on every pass. And that the fence doesn't flex under side pressure. If it's a cheapie fence, add a C-clamp at the back end so it doesn't move. If the board moves 0.005" toward or away from the blade, you've got serious divots and lumps in the surface.

If you've got your tablesaw running, I'd recommend that you use it to cut two 1 1/2" rails out of some scrap wood. Use your method above to quickly rough the mahogany board down to 1 3/8" thick. Clamp or screw the rails down on either side, and use the router to trim the last bit off, making a flat surface at 1.25".

 

[Bruce Johnson]

Over on another thread, Chinjazz was asking about good ways to put metal rails along the top of the side rails of routing fixtures like we've been talking about here. In particular, on a neck routing fixture, where you may also want to use a radiused-base router to cut the radius on a fingerboard.

Here's a re-post:

Yes, putting round tubes or rods along the top of the rails on a neck routing fixture makes them more versatile. A flat base router can ride on the top for flat cuts, and a radiused base can ride along the outer edges to make radiused cuts.

A side bonus is that the router base sliding on a rounded tube or rod tends to clear itself of chips and sawdust.

On my first neck routing fixture, I used 1" dia aluminum tubing. I cut a shallow V down the tops of the two side plates. Two passes down the table saw with the blade at a shallow angle. Then the tubes are epoxied to the MDF. That worked well and has lasted well. I made this fixture in 1993 and used it regularly up to about 2000.

On the newer version of the fixture, I used 3/8" dia aluminum rod, set into simple rabbits cut in the outer edges of the plates. Epoxied on. The rabbits are 1/4" down from the top and 3/8" in from the side. So the rods are flush with the outside but stick up 1/8" above the tops of the plates.

The main reason I did this was to keep the inside surfaces of the plates smooth. All the neck holding blocks have to slide in and out of there. On the earlier one, they were catching on the tubes. This is a better design.

Note the duct tape on the left side! After 18+ years of hard use, the rails are breaking free from the epoxy. I need to rebuild it. I'm thinking I'm going to do the same thing, but with 3/8" stainless rod instead. And do a better job epoxying it, using tape dams to get the epoxy to surround the rods better.

 

[chinjazz]

Over on another thread, Chinjazz was asking about good ways to put metal rails along the top of the side rails of routing fixtures like we've been talking about here. In particular, on a neck routing fixture, where you may also want to use a radiused-base router to cut the radius on a fingerboard.

Here's a re-post:

Yes, putting round tubes or rods along the top of the rails on a neck routing fixture makes them more versatile. A flat base router can ride on the top for flat cuts, and a radiused base can ride along the outer edges to make radiused cuts.

A side bonus is that the router base sliding on a rounded tube or rod tends to clear itself of chips and sawdust.

On my first neck routing fixture, I used 1" dia aluminum tubing. I cut a shallow V down the tops of the two side plates. Two passes down the table saw with the blade at a shallow angle. Then the tubes are epoxied to the MDF. That worked well and has lasted well. I made this fixture in 1993 and used it regularly up to about 2000.

View attachment 3283006


On the newer version of the fixture, I used 3/8" dia aluminum rod, set into simple rabbits cut in the outer edges of the plates. Epoxied on. The rabbits are 1/4" down from the top and 3/8" in from the side. So the rods are flush with the outside but stick up 1/8" above the tops of the plates.

The main reason I did this was to keep the inside surfaces of the plates smooth. All the neck holding blocks have to slide in and out of there. On the earlier one, they were catching on the tubes. This is a better design.

View attachment 3283007

Note the duct tape on the left side! After 18+ years of hard use, the rails are breaking free from the epoxy. I need to rebuild it. I'm thinking I'm going to do the same thing, but with 3/8" stainless rod instead. And do a better job epoxying it, using tape dams to get the epoxy to surround the rods better.

Hi Bruce,

I'm curious about the two threaded rods w/knobs on the inside of this newer fixture.
Do they serve a purpose to raise up the nut end for a tapered cut when radiusing?
I'm doing a few more modifications to my rendition of your master piece

Thanks!

 

[Bruce Johnson]

Hi Bruce,

I'm curious about the two threaded rods w/knobs on the inside of this newer fixture.
Do they serve a purpose to raise up the nut end for a tapered cut when radiusing?
I'm doing a few more modifications to my rendition of your master piece

Thanks!

Yes, those are jacking screws that are used to adjust the height of the two ends of the neck. I guess I need some better pictures of that wood frame to show how it works. Turning those screws raises and lowers the two clamp blocks that are holding the neck. I set the height of the neck at either end using homemade wooden gauges. I have a different gauge for each radius that I cut.

A note that maybe you haven't considered: On this type of fixture rig, with the radiused base on the router, the router bit has to extend a little bit below the base in order to be able to cut. But, when you extend the bit down, you are actually reducing the radius that it will cut.

For example, if the curved sides of your router base are cut to 12" radius, and you then extend the router bit down 1/2" below those curved base sides, then you will actually be cutting an 11 1/2" radius. So, the height of the fingerboard in relation to the two aluminum rails is important.

On my rig, I standardized it so that the router bit normally is extended 1/4" below the base sides. So, the base that I use to cut 12" radius is actually cut to 12 1/4" radius. All of my radiused bases are the same way; the base side radiuses are cut to 1/4" larger than the fingerboard radius that they are intended to cut.

And that's what the jacking screws and the wooden gauge are for. I use them to set the height of the neck so that the finished surface of the fingerboard ends up at 1/4" less than the radius of the router base, right at the radius I want.

And, in most cases, I bias the height settings at the two ends, raising the nut end a small amount to put some taper in the fingerboard. To make the edges look more even in height.

 

[chinjazz]

Yes, those are jacking screws that are used to adjust the height of the two ends of the neck. I guess I need some better pictures of that wood frame to show how it works. Turning those screws raises and lowers the two clamp blocks that are holding the neck. I set the height of the neck at either end using homemade wooden gauges. I have a different gauge for each radius that I cut.

A note that maybe you haven't considered: On this type of fixture rig, with the radiused base on the router, the router bit has to extend a little bit below the base in order to be able to cut. But, when you extend the bit down, you are actually reducing the radius that it will cut.

For example, if the curved sides of your router base are cut to 12" radius, and you then extend the router bit down 1/2" below those curved base sides, then you will actually be cutting an 11 1/2" radius. So, the height of the fingerboard in relation to the two aluminum rails is important.

On my rig, I standardized it so that the router bit normally is extended 1/4" below the base sides. So, the base that I use to cut 12" radius is actually cut to 12 1/4" radius. All of my radiused bases are the same way; the base side radiuses are cut to 1/4" larger than the fingerboard radius that they are intended to cut.

And that's what the jacking screws and the wooden gauge are for. I use them to set the height of the neck so that the finished surface of the fingerboard ends up at 1/4" less than the radius of the router base, right at the radius I want.

And, in most cases, I bias the height settings at the two ends, raising the nut end a small amount to put some taper in the fingerboard. To make the edges look more even in height.

That’s an interesting kit in the middle there.
Seems like it would do a nice smooth job uniformly dialing in the precise angle (with your set gauges guiding you of course). I might try to rig my fixture with something similar.

Thanks for sharing this other point about the reduction of radius as the bit lowering down. I hadn’t considered it, but now I realize I should .

Trying to unpack what you said, is it basically the amount the bit extends below the flush surface edge of the bottom curve of the router frame equals the amount to compensate for when cutting the template out?

The neck I just cut, I raised up the neck as close as possible where the side to side motion didnt rub the board (was close) and the bit was poised to take about 1/16” off the corner edges.... I took a little off the left and right sides but nothing off the middle I a few successive passes lowering. Then used a radius block and paper to finish the job. Using the block was my insurance basically.

 

[Bruce Johnson]

Trying to unpack what you said, is it basically the amount the bit extends below the flush surface edge of the bottom curve of the router frame equals the amount to compensate for when cutting the template out?

Yes, that's what it is exactly. You are moving the tip of the router bit directly toward the center, reducing the radius.

 

[Bruce Johnson]

That’s an interesting kit in the middle there.
Seems like it would do a nice smooth job uniformly dialing in the precise angle (with your set gauges guiding you of course). I might try to rig my fixture with something similar.

Following up on how that jacking screw thing works in my neck fixture. It's a pair of maple beams that fit under the clamping blocks. The one end rests on the bottom of the fixture, and the other end has the jacking screw. The jacking screw is a short piece of 1/4-20 threaded rod with a knob on the top. There's a 1/4-20 T-nut in the bottom of the maple beam that it threads into.

One beam splits out into a fork:

So that it fits around the other one like this. One slides within the other, so I can adjust the spacing of the clamp blocks to fit the length of the neck.

The clamp blocks fit into those notches, which holds them vertical while I'm getting everything adjusted. This is the assembly outside of the fixture. You can see how the two jacking screws finely adjust the height of the clamping blocks over a range of about 1/2", independent from each other. This makes the setup fast and easy. If I need to raise them up higher, I have strips of wood that I slide in under the whole assembly.

I have about 50 different clamp blocks made up to fit different widths of necks, specialty headstocks, widths of heels, special types of heels, etc. They are all made from rectangles of 3/4" MDF. Over 20+ years of use, I've used this fixture with almost every possible size and style of instrument necks.

And here's the assembly sitting down in the fixture.

When the neck is all adjusted for height at each end and side-to-side level, tightening the two horizontal bolts squeezes the sides of the fixture together, squeezing the clamp blocks, which squeeze the neck, because they are split down the middle. It all locks up solidly.

This is the best system I've come up with for holding all kinds of necks solidly while routing them.

 

[chinjazz]

Wow, this is great Bruce!

Thanks for going into such detail with pictures on your adjustable neck height clamping system.
I hadn't realized the fixture had a side force clamping action from prior pictures. Very nice!

Having a fixture like this is great because you wouldn't have to use double stick tape to keep the neck in place

Couple of questions, On the clamping blocks, do you make that center line be a little wider than a straight band saw cut? Looks slightly wider. Also, What's the extra side "notch" on the nut side clamping block used for?

Again, thanks!!!

 

[Bruce Johnson]

Having a fixture like this is great because you wouldn't have to use double stick tape to keep the neck in place

Couple of questions, On the clamping blocks, do you make that center line be a little wider than a straight band saw cut? Looks slightly wider. Also, What's the extra side "notch" on the nut side clamping block used for?

Yes, double stick tape saves the day for many emergency and special setups. But it's better to make up something more solid if you can. Double stick tape can often move just a little bit under load, and ruin a part. I use it sometimes when I need to, but I try to avoid it.

On the clamping blocks, note the 1/2" hole down low. That's to keep it from splitting. I bandsaw down to that hole in two cuts, in a slight V. So, yes, the split is a little wider at the top. Also, after laying out and cutting one of those clamp blocks, I hold them against the edge sander to put a slight taper on the two sides. They are about 1/8" wider at the top than at the bottom. That helps with the clamping. Each clamp block has about 1/8" of range of clamping width. I have blocks for 1 1/2", 1 5/8", 1 3/4", 1 7/8", etc.

I was looking at the pictures, and I honestly don't remember what that notch on the side of the 1 5/8" block was for. Some special setup way back. Some of those clamp blocks are more than 20 years old.

 

[chinjazz]

Thanks Bruce!

 

[MovinTarget]

I, uh, took a stab a recreating your jig base... I don't think I nailed it to the point of perfection or laugh-ability (depending on the usage of the phrase "nailed it"

But I only had finished MDF boards to start off with, so at least they are low friction...

 

[dwizum]

Are any of you using router planing fixtures on very thin, figured stock?

I have a figured walnut panel I'll be using for the back of a uke bass. It's at about .110 and I want it around .080. I don't trust a planer because of the figure. I no longer have access to a thickness sander. It's too thin to be stable enough to clamp in my current router planing jig - so I'm thinking about double sided taping it to an mdf panel and then clamping that in the fixture. Thoughts?

The other option is build a thickness sander but I need another big side project like a hole in the head right now...

 

[Jon Clegg]

Are any of you using router planing fixtures on very thin, figured stock?

I have a figured walnut panel I'll be using for the back of a uke bass. It's at about .110 and I want it around .080. I don't trust a planer because of the figure. I no longer have access to a thickness sander. It's too thin to be stable enough to clamp in my current router planing jig - so I'm thinking about double sided taping it to an mdf panel and then clamping that in the fixture. Thoughts?

The other option is build a thickness sander but I need another big side project like a hole in the head right now...

I usually fix work to the bed of my router sled with hot melt glue around the edges -- it leaves less residue. If you're particularly worried about residue, you can cover the areas where the glue will be with painters tape.

 

[dwizum]

So, the hot glue just goes around the edge of the piece in a thick bead? All the way around the whole perimeter? Or does it go between the piece and the base, but just near the edges?

I hate double stick tape, hot glue sounds like a good alternative.

 

[Jon Clegg]

I just glue around the edges with the work flat on the bed. Doesn't even need to be a continuous bead, just a couple of globs, to your satisfaction.

 

[Matt Liebenau]

With thin stock my concern with double stick tape would be breaking the wood trying to get it off of the tape. With hot glue around the edges you should, at worst, need to cut around the edge to release it.

 

[Jon Clegg]

With thin stock my concern with double stick tape would be breaking the wood trying to get it off of the tape. With hot glue around the edges you should, at worst, need to cut around the edge to release it.

And as I said, you can apply painters tape to the thin stock rather than gluing directly to the wood. I did this to secure routing templates to a quilted maple top where I was (perhaps overly) concerned about ripping out chunks of the top when I removed the templates.

 

[Bruce Johnson]

Yes, hot glue is one good alternative to tape. Another is screws. Pick 6 or 8 spots in the waste wood around the outside. And if you can, one in the middle, in the middle of a pickup rout location. Use little #4 x 1/2" flat head screws to fasten it down to the backboard, countersinking the holes in the wood deep enough that the router bit won't hit the screw heads at the final cutting depth. If you want to be extra safe, use brass screws rather than steel screws. That way, if you do skim one with the router bit, it's not going to chip the bit's edge.

Another option is to glue it onto the body as it is, over thickness. Then set up the whole body in the router planing fixture to thin down the back cap.