Official Luthiers Forum!

Ever since I saw Frank Ford's Precision Saddle Mill I have wanted to make
my own. I finally collected all the bits and pieces I needed and built my
own version of Frank's tool.

The mill slides back and forth on two linear bearings running on 5/8"
rails with stop collars to limit the cutting length. The up and down
motion is from a linear slide I picked up on EBay. I'm not sure what type
it is, but it was the right dimension for the project. The up and down
travel is about 1.5".

Here she is:



The red circle is the collar that limits the side to side motion.



The up and down motion and the cutting depth are adjusted up here.



First, I made up this little step block.



I slip the step block with the depth I want to cut under the height
adjustment screw and lower the cutter until it touches the bridge. Then I
lock the height adjustment screw with the set screw sticking out towards
the back. Now I can fire up the router, remove my little block and plunge
the cutter to a known depth.

So far this rig has worked out very well. It is very stable and if need be, I
can go back and deepen my cut without widening the slot.

Enjoy!

Louis

_________________
- Louis Freilicher

Oh No! Not another learning experience!

That's nice. Looks like a well thought out tool that will be perfect for the job.

Al

Thanks Al.

Since the picture function is back up I'll add one of the rig at work.



And the final product.




     Louis

_________________
- Louis Freilicher

Oh No! Not another learning experience!

That looks really slick Louis. How do you set the angle of the saddle slot?

_________________
Joe Breault
Merrimack, NH
Perpetual novice

Yes! Very good job on the new tool Louis.
Nice job on the old Gibson slot too!

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Anderson Guitars
Clearwater,Fl. 33755

nice job of replacing the execrable adjustable saddle on the gibson(?).

i notice that you used considerabley less compensation angle than gibson did. comments?

Thanks for the replies all. The guitar is a 50's Gibson that originally had
the adjustable saddle. Someone had already removed the metal saddle
and inserted an ebony plug but left all the hardware in the top. I removed
the bridge and adjustment hardware and glued a rosewood plug into the
bridge before I re glued it.

Joe- The angle of the slot is set by placement of the rig. I measure out
and mark the top of the bridge for the new slot, then loosely clamp the
rig to the guitar and wiggle things around until the pencil line lines up
with the center of the router bit as I slide it from side to side.

Michael- The original bridge footprint was a few degrees off
perpendicular to the centerline of the top and to cover a few old boogers I
squared it up a bit.
My usual compensation calculation is to measure the 12th fret distance,
multiply by 2, add .1 and mark that distance between the D and G strings
on the bridge. For the low E I add .175; for the high e I use the
mathematical scale length. Then connect the dots on the bridge and set
up the mill as above.

Louis

_________________
- Louis Freilicher

Oh No! Not another learning experience!

Regardless of how much time or money it took to make, you will never cease
to be glad to have a good saddle routing tool like that. I made one of a
slightly different design a while ago and use it quite often, even just for
cleaning up sloppy slots. In fact I have two saddle slots that I look forward to
the pleasure of routing in the morning.

Having the right tools can make jobs like this so much easier. Nice work on
the mill.

_________________
Eschew obfuscation, espouse elucidation.

Very cool set-up! Thank you for sharing.

My mill is of a different design, but here's a few shots. The main
points are the same (1/4" shank lam trimmer cutter, linear
bearing travel and plunge, width and depth stops) with a
slightly different layout. Here is a top/side view on a new bridge
I had to slot this morning.

05_223330_bm1.jpg">

I know it's a bit silly and superfluous, but I just couldn't resist
taking the bulb and lense from a cheap laser level and
mounting it on the carriage.

05_223530_bm2.jpg">

Here is the back with a lead screw for plunging on the right, a
depth stop in the middle, and a spring balance with a lock lever
on the left which I never really use.

05_223740_bm3.jpg">

This is a shot of the other side with a view of the end stops that I
use. This slot I had to widen out and clean up this afternoon.

05_223943_bm4.jpg">

And on the front side put another stop for odd width slots that
may require moving the carriage for a second parallel pass.

05_224141_bm5.jpg">

When I made this I thought for sure that I had spent way too
much time and money in making this tool. Now that I've been
using it though I can't imagin going without it. Making a good
laminate trimmer saddle mill is an investment you will always
be thankful that you made.

_________________
Eschew obfuscation, espouse elucidation.

Sorry, I knew that the photo posting wouldn't work with Safari
on my Mac, but it looks like the forum software doesn't agree
with Mac Explorer either. I guess I'll have to try downloading
Firefox for this forum.

_________________
Eschew obfuscation, espouse elucidation.

David, I have that same problem too. I find that if I rename my jpgs a
single character name, such as x.jpg, they fit into one line and show up
properly.

_________________
Mike

"The Dude abides. I don't know about you but I take comfort in that. It's good knowin' he's out there. The Dude. Takin' 'er easy for all us sinners. Shoosh." The Stranger

Aww Rats, I want to see your mill David.

After I cut my first slot with the mill I kicked myself for waiting this long to
build it. A .093 slot from a .093 bit.... Finally!
There is some time and money to invest in such tooling but it is worth every
minute and dollar spent.

Please try and post those pics again.

Louis

_________________
- Louis Freilicher

Oh No! Not another learning experience!

Okay, I got it working, kind of. With the file name shortened to one letter it
will work, but if I add any text lines between the third and fourth photos, it
will shift all the links to two lines. Weird.....

Anyway, captions are as listed above.

_________________
Eschew obfuscation, espouse elucidation.

That sure is a fancy set-up. I am looking for the "Patent Pending" stamp on that machine. Did you machine all the parts yourself David.

Louis and David, I can't see from your photos how you account for the curvature of the guitar top in the way the bases of your jigs sit on the guitar, to ensure a slot of even depth. Whether it's a brand new guitar with a spherically domed top, or an older guitar that can have all sorts of interesting topography from years of distortion under string tension... what's your mechanism for setting up your jig so that it sits stable and in the plane you want it in?

Thanks for posting the pics!

_________________
Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

David,

That is some fine machining on the mill there, excellent work all around
and a very well thought out design.   I guess that sometime in the future I
will want to adapt my machine to be able to widen slots while with
precision.

It looks like your rig has a vacuum clamp built into the bottom?

I lined the bottom of my rig with two layers of gasket sealing cork
available at the hardware store etc. This seems to work well and keeps it
from skidding around. The base plate is flat so it does flatten out the
domed tops a bit, I try not to over-clamp the rig and my guess is that any
distortion in the cutting depth is minimal.

I would rather have the rig be super stable than find out what happens if
the bridge is left to vibrate while the router is running.

Louis

_________________
- Louis Freilicher

Oh No! Not another learning experience!

Louis,

I really like your jig. Plan on offering any for sale? If so sign me up!

David, that thing looks like something precise enough for NASA...Amazing...WOW! you guys are very creative.


D

_________________
Dave Bland

remember...

"If it doesn't play in tune...it's just pretty wood"

Thanks guys. I have had several people want to buy it, but I don't
currently plan on making any more of these. The time I had to put in to it
would make it rediculously expensive, and I keep busy enough with fixing
guitars. Perhaps someone should get in touch with Bishop Cochran to
suggest making a carriage with these features for his PC310 plunge base.
He's certainly a much better machinist than myself, although I'd guess he
would have to charge at least $1200-$1500 or more for the whole setup.
With how slow I am at layout and setup I would have to charge even more.
There's a lot of different ways I'm sure to make a tool to do everything
this does. I'm sure there would be ways to adjust Louis mill the allow for
the same features.

As to the flexing of the top when it is clamped down, I've haven't been
too concerned with it. The base is flat with about 1/2" of padding to seal
and fit contours, but under vacuum It locks down very firmly and will
indeed flatten a top slightly. Still, I don't think any significant or
measurable amount of flattening occurs to the bridge itself that could
result in a curved slot. At the 2 1/2"-3" span where the slot is set you
have a thickness of about 1/2" to 9/16" of maple spruce and ebony
laminated, and I believe most of the flattening will occur from the wings
outward leaving the saddle region relatively unaffected. It is a good point
to bring up though, and I should probably check the change under
clamping pressure. I have a 4' straightedge with a .0001" dial indicator in
the center that I'll use to check deflection next time I cut a slot.

I was going to post a shot of the vacuum clamping bottom of the base,
but for some reason I can't get the image link to fit on one line in the text
box today. Maybe I'll try again tomorrow.

_________________
Eschew obfuscation, espouse elucidation.

There, I got it to work.

Louis, I meant to ask how long or difficult you felt it was to make that mill. I
have a tendency to over-engineer some things, which is probably why my
mill would be to costly to produce. Perhaps you should consider making
some to sell if you think it's doable - It looks like you have at least one
buyer already lined up.

_________________
Eschew obfuscation, espouse elucidation.

Well, I'm not showing another jig again! Great stuff, guys.

_________________
Rian Gitar og Mandolin

David,

Thanks for posting that bottom shot with the vacuum seals. I built one of
the Joe Woodworker vacuum clamping systems but have yet to fully
integrate it into my shop. Again being an eBay scroung-o-holic I may
have wound up with a vacuum pump that is slightly underpowered for
what I'm asking it to do.

The mill was also a scrounged up project that took on design changes as I
acquired the parts. I built the base and attached the rails before I found
the slide way that controls the up and down motion. Once I had all the
pieces and a pretty good idea how I wanted it to work the assembly was
not too difficult. I did not spent much time milling very piece to a fine
finish, basically I ground and filed off the band saw marks and rounded
off all the sharp edges and called it good enough.

This was basically my first real machining project and I have a lot more to
learn. Watch out, machining is as addictive as lutherie!

If I had to estimate a budget in terms of money and time I would say
$150 in parts and about 6 hours work. If I were to build it again I could
probably cut the build time in half but the parts budget would depend on
what's available to scrounge this week.

This may be common knowledge but for those of you thinking about
building a rig like this or something else; aluminum cuts at the same
speed as wood. Your blades will wear a bit faster but you can work this
stuff on the band saw, table saw, drill press and sander you already own.

Dave SKG- I would be glad to work up a mill for you drop me a PM or you
can email me from my site.

Louis

_________________
- Louis Freilicher

Oh No! Not another learning experience!

David and Louis, thanks for addressing my question.

David, I hadn't even though about the possibility of flexing the bridge downward a bit (as a result of flattening the top somewhat) while routing, and thus ending up with a saddle slot whose bottom has a slight convex curved when you remove the rig... but, now that you mention it, I'm reminded of a "Trade Secrets" email from Dan Erlewine in which he describes his method of using a jack inside the guitar, lifting the bridge area to simulate the convex bridge-flexing effect of string tension, while routing the saddle slot, so that the slot bottom will be truly flat when the guitar is strung up. When I read that I wondered whether that is a common practice among repair people; or, conversely, whether slightly curved-bottom saddle slots resulting from not using some such method are a common problem.

_________________
Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/