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Tool Show & Tell - Saddle Slot Mill
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=43204		 Page 1 of 4
Author:  David Collins [ Sat Apr 12, 2014 11:44 pm ]
Post subject:  Tool Show & Tell - Saddle Slot Mill
We get a lot of requests to see more about this tool, so I threw together a quick video showing it's features on Youtube.

[youtube]eY9_RRyxByg[/youtube]

http://youtu.be/eY9_RRyxByg

Hope this can give some helpful ideas on features and construction methods for anyone who might be looking to make their own version.

edit: ugh, I never seem able to figure out how to get a video to actually show up in the thread. The link should work anyway.
Author:  Clinchriver [ Sun Apr 13, 2014 8:02 am ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
Excellent video, very nice portable milling station, the laser takes it over the top :mrgreen:
Author:  johnparchem [ Sun Apr 13, 2014 8:35 am ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
Thanks for posting. I can not replicate the tool but I still found seeing how you use and adjust it very informative. With regard to showing youtube, it seems every BB requires a different incantation before the index. This one wants http://www.youtube.com/watch?v= before the index.
Author:  MaxBishop [ Sun Apr 13, 2014 8:42 am ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
Hi Dave,

That was awesome! I am delighted to see you posting on the OLF and look forward to more of your gadgets, tips, etc. A suggestion for a future video might be the cutting of a tiny ledge around the base of a bridge prior to gluing.

It was great to visit your shop.

Thanks,
Max
Author:  meddlingfool [ Sun Apr 13, 2014 9:20 am ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
That's a pretty slick piece of kit...
Author:  David Collins [ Sun Apr 13, 2014 10:06 am ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
Thanks all - and Max, that's certainly on my list I videos to shoot.

Now here's my dirty little secret - the machining on this setup is really remarkably crude, far from meeting any decent machinist standards. That's the beauty of linear bearing systems though. So long as the base is solid and close / consistent enough (things like the sides of the motor holder have to be good and parallel), then the only key precision is in alignment of the rails and bearings as you fasten them down.

If I were to try and make this like a Bishop Cochran base, it would have been much more challenging and demanded incredibly higher standards of precision in machining. The bearings are really a way to cheat, but given how well it has served for cutting hundreds of saddle slots, I'm not ashamed of this shortcut, and it does the job remarkably well.
Author:  WudWerkr [ Sun Apr 13, 2014 10:24 am ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
I need to exactly that with one of my Guitar Builds , I want a wider Saddle in it and dont want to have to take the Bridge off. I have been trying to come up with a poor mans verson . LOL could have probably taken bridge off and fixed it and reglued by now lol .
Author:  James Ringelspaugh [ Sun Apr 13, 2014 10:57 am ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
That is an awesome little mill. Very impressive indeed.
Author:  Tom West [ Sun Apr 13, 2014 2:10 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
Fantastically brilliant................!!! Did I notice a laser .....?? Built into the router?? Very impressive how fast both operations were done. Congrats and Thanks David.
Tom
Author:  Haans [ Sun Apr 13, 2014 3:19 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
Pretty fancy stuff there...nice vid!
Author:  James Orr [ Sun Apr 13, 2014 4:55 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
I know there was some love lost between us in the last thread ( [uncle] ), but this was a very nice, impressively done video. Thanks.
Author:  Jim Watts [ Sun Apr 13, 2014 10:25 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
That's awesome!
Author:  David Collins [ Sun Apr 13, 2014 11:38 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
Thanks all - I'm glad it was interesting! Keep in mind that I'd gone through at least 4 or more versions of slotting jigs before arriving at this one, so this is a culmination of much trial and error, and learning from many weaknesses of prior designs. If I had to estimate the cost of development and construction of this tool, it would be well in to the thousands of dollars. Even there though, it has paid for itself so many times over that it has been far more than worth it.

With a so-so saddle slot I used to hem and haw over setting up a more cumbersome jig where precise cuts were harder to set up and reliably achieve. Now if I run in to any problem from rough or warped edges to poor piezo balance from a warped bottom, the solution is so simple - it takes less time to clean up a slot than it does to try and figure out a way to deal with a compromised one.

We ave actually looked in to having an updated version of this made for sale, as we certainly have access to more advanced machining resources now than when I made this original version, and I've spent enough time with it to refine some enhancements that could be incorporated in a new version. No promises (it would still be a relatively expensive tool compared to plastic / Dremel alternatives), and I never planned on getting in to the luthier tool trade, but I've had enough interest that it may be something available on a wider scale in the future. We'll see.

In any case, I develop tools like this because I see a need for them in my own use, and this is by far one of my favorites. After working with this one for so long, I can't imagine going without it anymore.
Author:  david farmer [ Mon Apr 14, 2014 10:36 am ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
Thanks for the video. Very nice.
I have put off for years building a satisfying jig for saddle slotting. Always hoping to come up w/ something rigid and quick.
I like to think of myself as a skilled jig builder but the time and effort you must have put into that bad boy are impressive and intimidating!
That high pitch, zero lash, lead screw is what has me drooling. Mind if I ask where that came from?

Are you ever concerned w/ vacuum distorting the top or pulling a brace loose?
Or do you limit the pressure w/ a regulator? Sucking a highly bellied/arched top to a rigid Aluminum plate might make me hold my breath when I threw the switch.
maybe it is sacrilegious but I sometimes use re-slotting as a chance to put an ever so slight backward lean to the saddle on a rotated bridge especially if it will help w/ intonation. Is there a method you use control fore and aft tilt?

Sorry for all the questions. idunno You have obviously thought deeply about this subject it's hard not to try and pick your brain.
Author:  David Collins [ Mon Apr 14, 2014 3:25 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
Hi David - good questions, and ones I was concerned about when I started this as well. The vacuum pump I use pulls about 22-25 InHG, so around 10-12psi vacuum pressure. If I had to make a rough guess I'd say there's 15 square inches of surface area within the gasket, so probably in the 150-180 total force. It's spread out over enough area however, that it is almost like a series of small suction cups rather than one big one, and not really loading any broad areas.

The vacuum base is ~.170" aluminum, so with a moderately domed top not only does the gasket account for most of the conforming to the top, but the base will flex a bit as well. Then with fairly narrow feet on where the carriage (which is built on a .350" aluminum plate) meets the vacuum plate, the carriage section can remain pretty much free from distortion. There have indeed been cases though, where I've had tops so bellied or domed, that I've added supports under the ends of the vacuum base so that it would still suction down to the top, but not apply so much force as to try and flatten out the top as it clamps down to it. These cases are rare, but it's good of you to bring up because it can be a concern when a top is so domed that you may worry about stressing the braces.

There will of course be some inevitable distortion of the top (though extremely minor on the average soundboard), but I've checked the level of the slot base in several cases where I was concerned, and never been able to find any distortion through this short and stiff area of the saddle slot length.

As to tilting the slot back, I will do this on occasion by shimming the front edge of the base (where you see the cork lining in the video). I considered adding an adjustment for this, but it would have to be integral to the base rather than the carriage, or else parallel passes would create steps in the bottom. In the end I decided it was just simplest to shim under the front edge of the base when I needed to, and it works quite well for this.
Author:  theguitarwhisperer [ Mon Apr 14, 2014 3:51 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
I'd happily pay you $1000 for one of those.
Author:  Hesh [ Mon Apr 14, 2014 5:21 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
Whisperer $1,000 is likely what these might cost to produce.... :D

I wanted to mention that having access to one of these mills that David created has also changed how I build. No longer am I manipulating where the saddle slot and bridge will be and instead I install my bridges without slots and slot them precisely on the guitar.

Besides who would not want to play with the stinkin laser anyway.... :)
Author:  murrmac [ Mon Apr 14, 2014 5:30 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
Undoubtedly the way to go ...it's not like anybody could actually measure the distance between the nut and a pre-slotted bridge and clamp it onto the soundboard accurately.
Author:  Link Van Cleave [ Mon Apr 14, 2014 6:08 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
murrmac wrote:
Undoubtedly the way to go ...it's not like anybody could actually measure the distance between the nut and a pre-slotted bridge and clamp it onto the soundboard accurately.


And this sarcastic negative comment adds the the discussion how ?? idunno
Author:  David Collins [ Mon Apr 14, 2014 6:25 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
murrmac wrote:
Undoubtedly the way to go ...it's not like anybody could actually measure the distance between the nut and a pre-slotted bridge and clamp it onto the soundboard accurately.


Sure seems like it would be simple. Then of course there's all the Martins, Gibsons, and lot's of other makers who slipped on this one (even a few builds from some prominent members here that I've had to pull this out for). In any case, it's an invaluable tool for repair, and I never would have bothered with developing such a device if my primary focus were building. Now that we have it though, it's actually easier to cut the slot on a new bridge after it's on the guitar than it is to set up the mill to route it off the box. :D
Author:  david farmer [ Mon Apr 14, 2014 6:42 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
Thanks for the reply David.
Hesh, I'd love to play w/ lasers!
But if I start putting lasers on my jigs doesn't that put me on a list somewhere? Or does it go directly to Dick Cheney's desk?
Author:  RusRob [ Mon Apr 14, 2014 7:04 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
Nice job on the video Dave, Very concise and professional [:Y:] I appreciate the effort you put into that jig and I know it took a lot of time to develop it. It seems like you would be able to sell a few of them to production shops as I can see how it would pay for itself in no time.

I enjoyed meeting you when I stopped down pre A2 Open House. Just sorry I couldn't make it the day of. We had family come in from out of state and we had unexpected change in plans. I was planning on bringing my little parlor down to show you how the perfling came out. Ah well, so much for the best laid plans...

Thanks for posting the video. It has me thinking about how to make one. I could think of about 5 times in the recent past I could have used it.

Cheers,
Bob

Hey Hesh, Good to see you around the forum. I thought you may have gotten lost... laughing6-hehe
Author:  Flippo [ Mon Apr 14, 2014 7:50 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
That is an awesome tool! However, I would not use this in my "one a year" shop. I'll stick to my $5 plywood homemade jig and enjoy the enterprising efforts of others. Thanks for sharing. Tony
Author:  David Collins [ Mon Apr 14, 2014 9:38 pm ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
GuitarWhisperer - I may just follow up with this. The biggest challenge is of course one we're all familiar with - in trying to make a tool affordable for a larger audience, it gets cheapened up to the point of sacrificing some of the function, and I really don't want to go there. In fact, after putting this through near every possible scenario in the last 10 years (I've even used it for milling electric guitar pickup and tremolo cavities), I actually have some design changes in mind to improve it.

We have a machinist and brilliant engineer we work with who I may send this tool down to, along with my ideas for improvement, and see what they could do to improve it further, source parts, and come up with an estimate for production.

I really have no ambition to get in to the tool making and distribution trade, but this one is doable enough that we may at least try to do a batch or two for the number of folks who have expressed an interest (I've been offered $1500 cash for this one before, but there's no way I was going to let it go!). Even using all top quality bearings and parts, I've been crunching the numbers and think we may be able to have a batch made for under 1k each. If we can make it happen, I'll be sure to let anyone here who wants to get in on it know.
Author:  theguitarwhisperer [ Tue Apr 15, 2014 12:57 am ]
Post subject:  Re: Tool Show & Tell - Saddle Slot Mill
I'm serious, too.

That's a real tool, with many uses.

Let me know, please.
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