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  #31  
Old 05-09-2019, 07:24 AM
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Originally Posted by Quickstep192 View Post
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!
Sorry for the delay in posting more information about our CNC Quickstep. We use a ShopBot "Buddy" model. The bed of our machine measures ~24" x 36" which is the perfect size for guitar makers. Shop Bot makes MUCH larger machines that can handle 5' x 10' sheet goods for cabinet and sign makers. They also make smaller table top models which are perfect for hobbiests or inlay work. I know of several prominent inlay artists who are using the smaller table top machines with great success!

The CAD software, which came with our machine is made by Vectric and our version is called "V-Carve Pro". Vectric also makes another popular version called "Aspire". Shop Bot also includes 3-D software and a CAM package. We purchased our machine when they were first released at a cost of $4,995 well over a decade ago. Now the same machine is nearer $20,000.

This is a screen shot of the V-Carve pro software:







I am NOT a software guru by any stretch and I learned the software rather quickly. Initially it was rather intimidating but after I was shown the basics by a local High School Vo-Ag teacher, he had me up and running within 30 minutes and I learned the rest on my own. Shop Bot has an EXCELLENT forum and I was able to go there to get answers to every question that ever arose. Their forum is one of the main reasons I bought a Shop Bot because they answered all of my questions before I ever bought a machine and they patiently support newbies like myself with trivial questions without making me feel like an idiot. They also sponsor "camps" which are held in basements, garages and shops of other Shop Bot owners around the country. We attended a couple locally and it was a great way to meet other users and see examples of how they use their machines.

Our machine occupies about 3' x 4' footprint of floor space and quietly resides in a corner of our shop. The machine framework is made of 3/16" thick, powder coated, steel and also uses 80/20 aluminum members bolted to the steel frame. Every one of the three axis' of the machine smoothly glides on V shaped ball bearings and hardened steel ways and I have yet to see ANY wear or looseness on our machine.











The 3 HP water cooled spindle, which turns the carbide steel cutting tools, moves vertically up and down which is called the "Z" axis of the machine. The spindle assembly moves left and right, which is called the "Y" axis of the machine. Below the spindle is a brown 2' x 3' sheet of MDF (Medium Density Fiberboard). This is what the material which we are cutting is mounted to. This "MDF bed" of the machine moves front to back, which is called the "X" axis of the machine. The MDF board itself is called a "Spoil Board" and is meant to be consumed as the machine often times is programmed to cut through the work piece. The MDF starts out as 3/4" thick but as parts are cut it becomes necessary to resurface or flatten the spoil board's surface with a cutting tool. Its common to take a .010" - .020" depth of cut from the surface of the spoil board periodically to expose a new flat surface.

The most difficult task of using a CNC is trying to figure out how to hold the work piece down securely to the bed of the machine so it doesn't move around or slip while you are cutting a part. I have tried all sorts of methods over the years from screwing the work piece down to the spoil board, using a series of toggle clamps or hold down clamps, jigs, fixtures, double sided carpet tape, glue, small dedicated vacuum puck clamps and the method I have finally settled on to hold [most] work pieces, a vacuum bed.

Under the sheet of brown MDF, is a sheet of 1/2" thick plastic and under that is the actual factory supplied bed of the machine, which is an 1/2" thick 2' x 4' aluminum plate. Since you don't want to ruin the aluminum bed of the machine, most users bolt a MDF spoil board on top of the aluminum bed to protect it from "accidents" which can happen (please don't ask).

We bolted a sheet of 1/2" thick white plastic over the top of the aluminum bed and then machined a series of shallow interconnecting grooves in the plastic sheet which resembles the face of a waffle. Next we cut a 2" hole, through the center of the plastic sheet and aluminum bed and mounted a 2" flexible hose in the hole on the underside of the bed and finally connected the other end of the hose to a vacuum pump. Over the top of the 1/2" thick plastic grid is mounted the brown sheet of MDF which you see in the picture. This is not your regular grade of MDF but rather a material which is called Trupan which is a very porous variation of MDF. When the vacuum pump is turned on, it pulls a vacuum in all the channels of the waffle grid of the 1/2" thick white plastic sheet and then the entire face of the MDF becomes a vacuum or suction surface.

Lets say that we want to cut a rosette in a spruce top we would simply lay the spruce top on the surface of the MDF, turn the vacuum pump on and it becomes nearly impossible to move the spruce top on the bed of the machine. We can then program the software to cut the rosette channel precisely the size, depth and location we tell it to in the CAD software. The CAM software then converts the CAD picture into code which the CNC machine understands. The code is a complex series of exact moves to tell the CNC which axis to move in the X, Y or Z direction. The CAM software does this conversion all automatically in the back ground and you don't have to understand that language to use the machine, thank goodness!
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  #32  
Old 05-09-2019, 07:45 AM
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When we first purchased our CNC we ordered it with a 3HP Porter Cable router, because it was the most affordable option. It served our needs for many years. The downside to using a 3HP router is the NOISE. Its VERY, VERY, VERY loud and you can't be anywhere inside the shop without hearing protection. Imagine cutting a part that takes 2 hours, all the time working near the deafening noise of that router. The noise, even with hearing protection on is excruciating to say the least.

Shop Bot does order an upgrade option of a water cooled spindle, back then at a cost of ~$3000, which wasn't in our budget so we took the lower cost basic alternative. Looking back, I wished we would have just sucked it up and bought the water cooled spindle. Last year we finally upgraded to a spindle and what a blessing it is. We can turn the spindle on and you can barely hear it turning. When it is cutting wood the DB's go up but its still not in the dangerous range where its necessary to wear hearing protection.

The small gray colored box, in the upper right corner of the picture, is called a VFD (Variable Frequency Drive). This box controls the speed at which the spindle turns the carbide cutting tools. It's basically a speed control for the cutting tool.










On the right side of the frame you will see a cabinet we built to house a monitor, keyboard and two PC's. The PC in the bottom left of the cabinet is just a basic PC that we use ONLY for CAD and CAM software and runs on Windows 7. That is all that is on the machine. Its not connected to the internet nor should it ever be as this could infect the other software and cause all kinds of bugs and glitches in the machine. According to ShopBot you should use a dedicated PC computer for the machine, not MACs. The other computer, in the lower right corner, comes with the machine and houses all of the driver boards that run the machine. This PC is connected to the other PC via USB cables.






Sorry for the long winded post but I've tried to be thorough and no I'm not a rep or affiliated with ShopBot or any other CNC companies

Let me know if you have any additional questions.
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  #33  
Old 05-11-2019, 06:30 AM
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Tottie neck and tail blocks glued in place:











Followed by an application of the brand new super fragrant and most certainly odoriferous Spanish Cedar kerfed linings:
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  #34  
Old 05-11-2019, 06:52 AM
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What a fantastic insight into the world of CNC machines ... thanks Tim and Mary!
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  #35  
Old 05-12-2019, 06:54 AM
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What a fantastic insight into the world of CNC machines ... thanks Tim and Mary!
Thanks David. As you know CNC is only a SMALL fraction of what we do as builders. Its still 95% or perhaps even more, of pure hand work. No machine will ever deprive us totally of that pleasure.
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  #36  
Old 05-12-2019, 07:00 AM
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Originally Posted by Tim McKnight View Post
Thanks David. As you know CNC is only a SMALL fraction of what we do as builders. Its still 95% or perhaps even more, of pure hand work. No machine will ever deprive us totally of that pleasure.
Well put Tim!
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Old 05-12-2019, 09:39 AM
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Quote:
Originally Posted by David Wren View Post
What a fantastic insight into the world of CNC machines ... thanks Tim and Mary!
Thanks David. As you know CNC is only a SMALL fraction of what we do as builders. Its still 95% or perhaps even more, of pure hand work. No machine will ever deprive us totally of that pleasure.

Very interesting posts on the CNC. I do not comprehend how this stuff works. To me it is all MAGIC. hahahahaha

And I am really looking forward to my smelly new John Kinnaird as it will be mostly Spanish Cedar! I expect it will need an anchor or may float away...
And it will have a number of YOUR design features! Thanks again for all your assistance and encouragement.

And thanks again for these incredibly informative posts!

Blessings and Joy

Paul
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  #38  
Old 05-14-2019, 06:24 AM
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Quote:
Originally Posted by Guitars44me View Post
Quote:Very interesting posts on the CNC. I do not comprehend how this stuff works. To me it is all MAGIC. hahahahaha

And thanks again for these incredibly informative posts!

Blessings and Joy

Paul
Ha, I don't completely understand it either Paul. Its all Greek to me with a zillion 1's and 0's mysteriously whizzing around in the background.

In the mean time we are hanging around watching glue dry ... on Curly Myrtle bindings:































And also a smaller batch of Curly Maple bindings:
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  #39  
Old 05-15-2019, 04:53 AM
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Its a fact of life that sharp tools dull with use. I wish it weren't the case but stuff happens so oftentimes we have to take a break and hone cutting edges. This is not a commercial interjection for honing oil but Mary merely captured a non-guitar making photo op:
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  #40  
Old 05-16-2019, 05:23 AM
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Sharp cutting tools are always a pleasure to work with plus they are actually safer to use:
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  #41  
Old 05-19-2019, 06:56 AM
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One last sound check after voicing is complete:
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  #42  
Old 05-21-2019, 06:04 AM
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Distributing glue with the world's most high tech glue spreading device:










Closing the box on Tottie #3:
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  #43  
Old 05-21-2019, 08:18 AM
jaymarsch jaymarsch is offline
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Distributing glue with the world's most high tech glue spreading device:
Ah, the CNC machine now gets humbled as you bring in the really high tech equipment.

Thanks again, Tim, for giving us a great tour of how you use the CNC and the "fancier" finger techniques.

Best,
Jayne
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  #44  
Old 05-29-2019, 05:35 AM
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Hi Jayne,
Oft times the CNC sets quietly in the corner of the shop for weeks or possibly months without use but when called upon its always at the ready.




After both faces are on Tottie 2 its time to bind her up. Here is a shot of the freshly cut binding channels:










Four hands are always easier than two. Mary hands me strips of binding tape which which secures the bindings as the glue dries. Tottie 2 gets EIR bindings with Maple purflings. Its a very understated yet elegant look IMO.
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  #45  
Old 05-30-2019, 06:41 PM
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So, Tim, the professor in me wants to know how you arrived at this body shape. What you've CAD-produced looks significantly wider in the lower bout and narrower in the upper bout than the 1840s Martin with which you started. Just curious of dimensions (which don't appear on your page yet) and the "why" and the "how" of your mad-engineering genius in getting there. And a second question, if you'd be kind enough: How do you sense the Tottie being different from the Skeeter and Deacon, in particular, besides the lighter weight and single sides? I'd love to know your R&D process on this one.

Or is this one of those questions I ask of you where you'd have to kill me if you told me, as you've threatened on so many other occasions?!?
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