McKnight Guitars ... Shop Snippets '19

[Tim McKnight]

McKnight Guitars ... Shop Snippets ‘19

Our intention of this thread is to show you a glimpse of what goes on inside the McKnight Guitar work shop. We plan to share some of our methods and thoughts about why we do, what we do and open a window to the larger world a small glimpse of our tiny world in rural Morral, Ohio.

We recently released a new model and thought we would share our approach into transferring an idea into reality. In regards to our new parlor model, which we call Tottie, it all began from inspiration of seeing Songwriterfan’s recent acquisition of a mid 1840’s Martin. When I saw pictures of it, I was instantly drawn to it’s tiny shape and after hearing a recording of its tone, well that just sealed the deal for me.











AGF member SongWriterFan was gracious enough to sent me some pictures which I converted to pencil drawings on paper.











Next we digitally photographed the pencil drawing and imported the picture into our CAD program. Not wanting to do an exact copy of the Martin body, our software allows us to edit the size and every radii on the body until we are satisfied with the final shape and one which would not infringe on an existing and quite likely proprietary design.











After the final body outline is complete then we have to create several more files that include:
1 - 1/2 Body template
2 - Side bending forms (4 pieces)
2 - Side Bending Form Waist Cauls (2 assembled cauls consisting of 14 individual pieces)
1 - Body mold (2 halves of 6 identical pieces)
1 - Side lamination form (7 identical pieces to be glued together)
1 - Body Donut

























Next we convert these CAD (Computer Aided Design) files to CAM (Computer Aided Manufacturing) files which are machine tool paths which control the cutting spindle and tells it how to cut the 3/4” thick particle board sheets that will become the forms for our new model. Yes it’s a CNC (Computer Numerical Controlled) machine (oh my, he uses a CNC)!

Our CNC machine allows us to design and create a new model within about 2-3 full days of work. It’s an employee that we can tell what to do and it does precisely what we tell it to do within .001” and [usually] without talking back.

I think there is a lot of misunderstandings about the use of CNC machines and a certain stigma that removes the Artisan and old school skill of crafting guitars by hand. That notion couldn’t be further from fact. CNC is just another tool in our toolbox which some chose to use and some chose not to. In the end there is still about the same amount of “hand craft fitting” involved in the entire process of crafting a guitar by hand, with or without a CNC machine.

[Tim McKnight]

Using a CNC machine is not as simple as putting in a chunk of wood, clicking a mouse and out spits a guitar 10 minutes later. You still have to put in a LOT of time behind a monitor to learn the software and design files on the front end. Once you have made your CAD and CAM files, it does save you time down the road (IF) we choose to run that same part file again. That is where the time savings is actually realized. However, since most of the guitars we build are one-offs it is rare that we can use many of the files we create more than once.

I do find our CNC very useful for building tools, jigs and forms that we will use to “hand craft” our guitars. It’s just another tool in our toolbox that allows us to SEE the end result before we’ve spent hundreds of hours to build by hand.

We can render what the guitar may look like in different scale lengths or with different number of frets to the body. Here is an example of how 12 and 14 fret necks might look on a Tottie model and how the bridge placement shifts on the top. This software allows me to see where the bridge will be in relation to the center of the lower bout.





Its our hope as you read this thread, it will allow you to understand a bit of the thought process that goes into how we build our guitars. Keep in mind that there are LOTS of other ways to build guitars with no absolute right or wrong way to arrive at the final product. This is just the path that we have chosen to follow.

Thanks for following along and questions, comments or participation are always welcome.

[Mary]

I will be taking pictures periodically so you can see what I do throughout the process. I won't take as many pictures as I do for custom orders, but enough so you can see the luthier at work. ...which is what he does for fun even on ... his birthday ...

[Aura]

Interesting, i've subscribed to the thread already!

[Mary]

Originally Posted by Aura

Interesting, i've subscribed to the thread already!

I see this is your 7th post. Welcome to the AGF community where I have found the brotherhood of the luthiers a joy to be a part.

[nacluth]

Tim and Mary, thanks for the behind the scenes peek. It’s fascinating.

[Quickstep192]

Very cool stuff. Not surprising from an engineer become luthier!

If time and willingness permit, I'd love to see more about the machine itself (I want one!

Oh and by the way, Happy Birthday!

[riorider]

Nicely explained, Tim - and birthday wishes as well!!!

Phil

[David Wren]

Hey Tim ... I'm envious of your CNC skills ... and I agree that intelligent use of the CNC does not compromise the "hand made" aspect of our instruments at all. If you can use any tool to better make your templates and jigs, then it usually results in a better guitar. I don't utilize a CNC, but that's just because I'm too lazy to learn the skill. Thanks for the insight into your building process!

[The Growler]

Very cool. Thanks for sharing the process.

Happy Birthday Tim!

[Tim McKnight]

Thanks for the birthday wishes everyone. Its one of those days when we just can't escape father time because the clock keeps on ticking, doesn't it?

After the CAD and CAM files are complete its time to cut the parts. The first part is the 1/2 body template which is usually cut from 1/8" - 1/4" thick material. Most luthiers use a 1/2 body template. It takes up less storage space but more importantly it's more accurate to use a 1/2 template and flip it over so both halves of the guitar are exactly the same. I think this notion has evolved since most of us older builders began crafting our forms using a band saw or jig saw as the preferred tools to cut our forms to shape. It was cheaper to use a smaller size piece of wood. Another advantage is if we are building a cut away model we can easily add that 1/2 template to the mix.










The next form to cut is the bending form. This jig fits into our Fox style side bender. It requires 2 halves of 3/4" thick particle board joined together by wood dowels. The vertical slot in the waist accepts an aluminum key which holds the bending form securely in the Fox bender.









Here you can see the side bending form inserted into the Fox style side bender. You can also so the end of the aluminum key sticking out of the side next to the words "kerf slots up". I used to pre-bend kerfed lining and I wrote a note to remind me which way the kerfed slots faced.










Here you can see a cutaway side bending form inside the Fox style bender. We use this attachment to bend Venetian style cutways.











This form is what we use to laminate the sides. It requires us to cut 7 identical 3/4" thick particle board sheets and then glue them together. There is a 1/4" hole bored into each end of each piece. This allows us to insert a long dowel through the ends of all 7 pieces, which aligns each consecutive piece as they are glued together.










This form is called the outside body mold. It consists of 6 identical pieces of 3/4" thick particle board. Again it uses 1/4" dowels to align each piece as the stack is glued up. This form will hold the assembled rim, after the sides have been bent and cut to the proper overall length. I have built these molds in this method and have also built them as a solid form. Its a bit lighter weight and requires less material (cheaper) to construct the body mold in this hollow style.

[Neil K Walk]

I love these kinds of threads! As a player it's fun to play guitars but I've always been a "visual learner" so I LOVE pictures.

I remember way back when you unveiled the Deacon. I'd never dreamed of playing a handcrafted guitar but the experience I received from playing that little gem turned my guitar diversion into a full blown obsession of not only playing guitar but also learning about how they're made. While I'm curious about the guitar I have to be honest and say that I'm really loving the jigs! Making jigs has been more fun for me than some steps in the guitar building process. Is that because plywood is cheaper than tone wood?

That being said, this thread particularly intrigues me because when I was younger I had aspirations to become a technical illustrator and learned to model, animate and render in software very similar to CAD. I gave it up to focus on starting a family but have been looking to pick it up again. I'd love it if you could give a presentation at the McJam!

Happy birthday, Tim!

[jaymarsch]

I also enjoy these kinds of threads. Love getting a peek into inner workings of how luthiers make their magic.

Best,
Jayne

[Bill Kraus]

First of all Tim, it was nice to see the Misses and yourself at the Artisan show, and thanks for the classy Acoustic Guitar Forum badge, see you again next near. Second, happy birthday a day late!.
Great photos and a nice insight into how useful CAD and CNC can be for design and tool making, very nice.

[Tim McKnight]

Originally Posted by Quickstep192

Very cool stuff. Not surprising from an engineer become luthier!
Well after having spent 38 years in a Fortune 100 manufacturing plant, as a mechanical engineer, many of the skills I learned there naturally transferred over to lutherie. Efficiency and more specifically efficient use of your time and labor steps are one such skill set that has been hard not to think about on a daily basis. As we all are certainly aware time is money and since we only have a finite amount of time its up to us to use it as efficiently as possible.

As an example, early on in my lutherie career I started out with just one router. I quickly learned that I could use that tool for a myriad of repetitive tasks in the shop but a lot of my time was spent chasing bits, changing bits, making test cuts to set each bit's cutting depth to a unique task. It quickly became apparent that I could shave considerable time if I had a dedicated router for each machining operation. Gradually I started buying inexpensive used Ryobi trim routers from eBay and now I have about 16 of them at the ready.



If time and willingness permit, I'd love to see more about the machine itself (I want one!

I will certainly add your request to my list of topics to expound on and share with you. Please give me a few days ...

Originally Posted by David Wren

Hey Tim ... I'm envious of your CNC skills ... I don't utilize a CNC, but that's just because I'm too lazy to learn the skill. Thanks for the insight into your building process!

I too was in your position David because I knew very little about CNC and the software was Greek to me. It was during one of the talks that Kevin Ryan gave at Healdsbug that really got me thinking more seriously about a CNC. I think he said to justify the cost of a CNC purchase that you needed to be making over 10 guitars a year. That previous year I had built 32 guitars and was about to pull my hair out trying to balance a full time day job, family and building guitars. 90 Hour work weeks were extremely taxing on me so I knew I had to take the plunge to save my sanity. Kevin uses Haas machines and they were waaaaaay out of my price range so my search began.

Being an engineer I really wanted to build my own but in reality I just didn't have the time. I even purchased plans to build a small table top CNC out of wood! After considering the amount of time it would take away from my then TWO full time jobs I had no other choice than to purchase one. I've never been one to make snap decisions or instant purchases so my research led me to the machine I currently own, a Shop Bot "Buddy".

Shop Bot is very active in high school vocational programs as well as local trade schools and technical colleges. Two local schools had Shop Bot's so there was a talent pool available to get me up and running in a shorter amount of time. After I purchased my Buddy two of the local high school teachers came over to my shop and showed me the basics and had me running in a few hours. They were a God send. After that brief introduction I was able to learn most of the basic software skills on my own. Shop Bot has a user forum that was also extremely helpful when I ran into questions.

My first machine used a 3 HP Porter Cable router and I used it successfully for many years. About two years ago I upgraded to a water cooled spindle to replace the router. Using a router is VERY noisy and requires ear protection while its running but the spindle is whisper quiet. In hindsight I wished I would had purchased the spindle from the get go but it was a $3000 optional upgrade that I didn't have at the time.

Originally Posted by Neil K Walk

Making jigs has been more fun for me than some steps in the guitar building process. That being said, this thread particularly intrigues me because when I was younger I had aspirations to become a technical illustrator and learned to model, animate and render in software very similar to CAD. I gave it up to focus on starting a family but have been looking to pick it up again. I'd love it if you could give a presentation at the McJam!

Sorry but I had to laugh Neil. When we started building guitars in 1992 I didn't have any training, very few tools and zero jigs. I spent the entire winter with the book from the Guild of American Lutherie. Its exact title escapes me but it was a book of how to build the jigs you would need to build a guiatr. So we spent the entire winter building jigs, fixtures and unique tools, which many we still use today. It brings up fond memories of the time we spent the winter in the shop.

Originally Posted by jaymarsch

I also enjoy these kinds of threads. Love getting a peek into inner workings of how luthiers make their magic.

Best,
Jayne

Glad you are following along Jayne. What we do is not so revolutionary because I am sure many other builders use similar tools and process but at least it gives you a glimpse of what we do on a daily basis.

Originally Posted by Bill Kraus

First of all Tim, it was nice to see the Misses and yourself at the Artisan show, and thanks for the classy Acoustic Guitar Forum badge, see you again next near. Great photos and a nice insight into how useful CAD and CNC can be for design and tool making, very nice.

It was equally great meeting you at the show Bill and thanks for taking the time to stop by our table and introduce yourself. Its always fun for us to put a face to a name.