Robust Tru-Arc tool...

[Doug Rasmussen]

I saw this on Youtube. Search "Robust Tru-Arc". What do you folks think of it? I think it's great and surprised nobdy else (to my knowledge) has offered such a tool. But does it qualify as woodturning?

Way back in my pre-CNC days I built a similar mechanism. Mine would do both concave and convex surefaces (inside and outside of bowls). In the Youtube Brent mentions its use is for finishing cuts. Mine was substantially heavier, like 75 to 100 pounds, so heavy roughing cuts were no problem. Same theory of heavy mass in tooling I have for handles of hand-turning tools. Make the handles 50+ pounds to help prevent the tool bounce that leads to tear outs.

 

[Richard Coers]

$400 for some round bar stock, a collet, and a Heim joint seems incredibly expensive to me. I saw it at Turn On Chicago and thought it would be the easiest turning tool to make myself that I've seen yet. Second thought was that with 39 years of turning, I should be able to turn a fare curve all by myself.

 

[Richard Coers]

I saw this on Youtube. Search "Robust Tru-Arc". What do you folks think of it? I think it's great and surprised nobdy else (to my knowledge) has offered such a tool. But does it qualify as woodturning?

Way back in my pre-CNC days I built a similar mechanism. Mine would do both concave and convex surefaces (inside and outside of bowls). In the Youtube Brent mentions its use is for finishing cuts. Mine was substantially heavier, like 75 to 100 pounds, so heavy roughing cuts were no problem. Same theory of heavy mass in tooling I have for handles of hand-turning tools. Make the handles 50+ pounds to help prevent the tool bounce that leads to tear outs.

A handle can prevent tool bounce? I don't even know how you can get tool bounce. My tools stay on the rest very well. John Jordan used to turn with basically having the gouge handle in his belly button. He didn't get any tool bounce. A 50 pound tool would wear me out just picking it up.

 

[Curt Fuller]

Turning is kind of getting to be like the old Jetson's cartoons. You open the sliding door, put in a chunk of wood, push a few buttons and out comes a bowl.

Brent, I'm just kidding.

 

[Doug Rasmussen]

A handle can prevent tool bounce? I don't even know how you can get tool bounce. My tools stay on the rest very well. John Jordan used to turn with basically having the gouge handle in his belly button. He didn't get any tool bounce. A 50 pound tool would wear me out just picking it up.

By "tool bounce" I mostly mean the tool moving in and out while still on the tool rest. An obvious example I saw was a video showing the turner starting with a square blank and roughing it down to round, it was very obvious, every corner caused a bounce away from the work. Think about it, if the tool handle weighed 50+ pounds don't you think there'd be less tendency to push away from the workpiece? Or if you don't accept that make the handle 200 pounds. Robo hippy once posted about flat turning saying a pencil was held against the turning only marked on high spots where there was a slight push away from the wood where the turning was against the grain twice in every revolution.

John Jordan having the handle pushing on his belly button could be the equivalent of a weighted handle.

I fully realize a good many turners might not be comfortable with heavy handles. I wish someone would try it.

There also could be up-down bounce where the tool tip catches in the work and gets pulled down and the end of the handle is leveraged upward.. Don't you think the leverage of 50+ pounds out at the end of the handle would have the effect of lessening the downward bounce of the tool tip?

In CNC wood milling and turning the surfaces only needing very slight fine grit sanding is because of machine rigidity. Equate that rigidity to tool handles weighing perhaps a 1,000 or more pounds.

As to the Tru-Arc it seems a bit light weight to me, hence the usage as a finishing tool. If it was beefed up into the 200+ pound range for roughing and made of steel it might drive the price so high nobody could or would buy it.

 

[Mike Brazeau]

Looks like a tool in search of a problem. How many shallow bowls are you going to make in your lifetime? This is one of the easiest cuts there is to make. That bowl interior would take less than the time to set the thing up.

 

[Richard Coers]

By "tool bounce" I mostly mean the tool moving in and out while still on the tool rest. An obvious example I saw was a video showing the turner starting with a square blank and roughing it down to round, it was very obvious, every corner caused a bounce away from the work. Think about it, if the tool handle weighed 50+ pounds don't you think there'd be less tendency to push away from the workpiece? Or if you don't accept that make the handle 200 pounds. Robo hippy once posted about flat turning saying a pencil was held against the turning only marked on high spots where there was a slight push away from the wood where the turning was against the grain twice in every revolution.

John Jordan having the handle pushing on his belly button could be the equivalent of a weighted handle.

I fully realize a good many turners might not be comfortable with heavy handles. I wish someone would try it.

There also could be up-down bounce where the tool tip catches in the work and gets pulled down and the end of the handle is leveraged upward.. Don't you think the leverage of 50+ pounds out at the end of the handle would have the effect of lessening the downward bounce of the tool tip?

In CNC wood milling and turning the surfaces only needing very slight fine grit sanding is because of machine rigidity. Equate that rigidity to tool handles weighing perhaps a 1,000 or more pounds.

As to the Tru-Arc it seems a bit light weight to me, hence the usage as a finishing tool. If it was beefed up into the 200+ pound range for roughing and made of steel it might drive the price so high nobody could or would buy it.

If you start rounding the bowl blank from the face, you won't have your bounce issue. So learning a new and better technique would make your 50 pound handles obsolete. All the weight on a CNC lathe is not on the end of the cutter, especially if they are using a rotary cutter in a spindle. I guess you haven't seen a lot of CNC machining, 3D modeling takes quite a lot of sanding unless you run the program with an incredibly small step over. Even then, since a rotary cutter has very slow cutting speed at the center of a point, the wood can come out very rough. Try some red oak if you have a CNC lathe. I ran a 5'x10'x3' 5 axis CNC in the Caterpillar Model Shop for 12 years.

 

[hockenbery]

By "tool bounce" I mostly mean the tool moving in and out while still on the tool rest. An obvious example I saw was a video showing the turner starting with a square blank and roughing it down to round, it was very obvious, every corner caused a bounce away from the work. Think about it, if the tool handle weighed 50+ pounds don't you think there'd be less tendency to push away from the workpiece?

Lots of things cause tool bounce. Too much bevel pressure, too fast a feed rate, coming off the bevel, holding the tool too tightly……
A fifty pound handle would slow my feed rate considerably.

Here is a roughing cut on two surfaces. I’m using a wooden handled tool.
I probably get a slight bounce on the entry untill the bevel is locked in
The cut. And the surface cut
. .

 

[Mike Novak]

after I saw this I made my own version. It’s a bit different than the truarc, but same concept. I have a pretty bad tremor, so getting a smooth inside curve was giving me problems. I used it a couple times and decided that I’d be better served by practicing more with smoothing using a nr scraper.

The truarc looks easier to set up than my version, but won’t do smaller deep bowls. Not sure if I would have felt differently using it?

 

[robo hippy]

I did look at that Truarc thing and thought, hmm, well maybe some people may want/need it, but not me. Thought the same thing about pet rocks, but they were huge for a while.

For tool bounce, lots of things can cause it. For me, mostly uneven surfaces. Another one is the grain changing directions, and on bowls, for some reason this seems to be more of a problem for me on the outsides of the bowl, and not as much on the inside. With standard grain orientation/side grain turnings, you go uphill, down hill, up hill, and down hill with each revolution. This does cause some bounce whether you notice it or not. The more you clamp down on your tool, the worse it gets. Maybe I am better at floating the bevel on the inside of the bowl....

robo hippy

 

[Darryl Fective]

I saw a demo that the turner put the end of the tool handle in the tailstock opening and just gently swept an arc with it.

 

[Doug Rasmussen]

I guess you haven't seen a lot of CNC machining, 3D modeling takes quite a lot of sanding unless you run the program with an incredibly small step over. Even then, since a rotary cutter has very slow cutting speed at the center of a point, the wood can come out very rough. Try some red oak if you have a CNC lathe. I ran a 5'x10'x3' 5 axis CNC in the Caterpillar Model Shop for 12 years.

Hmmm..... 12 years, huh? That's the extent of your CNC credentials?

That puts me about 20 years ahead of you in CNC experience. Degrees in ME and computer science, 3 years at Boeing's think tank in South Park developing curve fitting algorithm's for 5 axis spar mills. One year in bioengineering at the university designing analog computers. Then 30 some years ago in self employment I bought my first CNC lathe and CNC mill retiring a few years back with 6 CNC machines. So, you want to talk about who has seen more CNC machining?

3D modeling, sometimes I do it. Other times I program cutter paths on the fly without a 3D model using the controller's macro language.

Here's part to think about. Cutter was 1/2", 4 flute square end carbide mill. 3 axis vertical mill with part standing up as shown. Program was less than 100 lines. Let us know how you think it was done needing no sanding.

 

[Gabriel Hoff]

I saw it too, but I don't really turn many bowls so it is not something I would purchase. But I like the concept and the creative thinking of @Brent@TurnRobust!

 

[Kevin Jenness]

Hmmm..... 12 years, huh? That's the extent of your CNC credentials?

That puts me about 20 years ahead of you in CNC experience. Degrees in ME and computer science, 3 years at Boeing's think tank in South Park developing curve fitting algorithm's for 5 axis spar mills. One year in bioengineering at the university designing analog computers. Then 30 some years ago in self employment I bought my first CNC lathe and CNC mill retiring a few years back with 6 CNC machines. So, you want to talk about who has seen more CNC machining?

3D modeling, sometimes I do it. Other times I program cutter paths on the fly without a 3D model using the controller's macro language.

Here's part to think about. Cutter was 1/2", 4 flute square end carbide mill. 3 axis vertical mill with part standing up as shown. Program was less than 100 lines. Let us know how you think it was done needing no sanding.


View attachment 66643

Egos aside, I would love to learn more about your process for making that piece. I am guessing that you have the workpiece fixed and a sharp, pointed, non-rotating cutter describing many spiral paths around it. Perhaps the work is on a rotating table. Make me look stupid. (Should not be difficult).

 

[Richard Coers]

Hmmm..... 12 years, huh? That's the extent of your CNC credentials?

That puts me about 20 years ahead of you in CNC experience. Degrees in ME and computer science, 3 years at Boeing's think tank in South Park developing curve fitting algorithm's for 5 axis spar mills. One year in bioengineering at the university designing analog computers. Then 30 some years ago in self employment I bought my first CNC lathe and CNC mill retiring a few years back with 6 CNC machines. So, you want to talk about who has seen more CNC machining?

3D modeling, sometimes I do it. Other times I program cutter paths on the fly without a 3D model using the controller's macro language.

Here's part to think about. Cutter was 1/2", 4 flute square end carbide mill. 3 axis vertical mill with part standing up as shown. Program was less than 100 lines. Let us know how you think it was done needing no sanding.

View attachment 66643

Hmmm..... 12 years, huh? That's the extent of your CNC credentials?

That puts me about 20 years ahead of you in CNC experience. Degrees in ME and computer science, 3 years at Boeing's think tank in South Park developing curve fitting algorithm's for 5 axis spar mills. One year in bioengineering at the university designing analog computers. Then 30 some years ago in self employment I bought my first CNC lathe and CNC mill retiring a few years back with 6 CNC machines. So, you want to talk about who has seen more CNC machining?

3D modeling, sometimes I do it. Other times I program cutter paths on the fly without a 3D model using the controller's macro language.

Here's part to think about. Cutter was 1/2", 4 flute square end carbide mill. 3 axis vertical mill with part standing up as shown. Program was less than 100 lines. Let us know how you think it was done needing no sanding.

View attachment 66643

Congratulations, you are better than me.

 

[Bill Blasic]

Hey I have a CNC machine, for less than a year now. Know next to nothing but having a great time with it and I have no ego trip about it😁

 

[hockenbery]

Hey I have a CNC machine, for less than a year now. Know next to nothing but having a great time with it and I have no ego trip about it😁

I’m amazed at what I’ve learned from teaching students over the years.
I also know a few turners who have been stuck at the advanced beginner level for decades.

Time is rarely the best measure of skills and knowledge.
I’m guessing you learned what you needed to know to make things you wanted to make.

 

[Doug Rasmussen]

Egos aside, I would love to learn more about your process for making that piece. I am guessing that you have the workpiece fixed and a sharp, pointed, non-rotating cutter describing many spiral paths around it. Perhaps the work is on a rotating table. Make me look stupid. (Should not be difficult).

Kevin,

It's just a matter of repeating a number of times the same relatively simple cutter path.

First position the cutter at the top of the part. Plunge down cutting the three radii. Move the cutter back to the top of the part. Do an axis rotation, in this case I used 1 degree rotation. The part doesn't actually rotate, but the controller adjusts the next cutter path as if there was rotation. Position the cutter's next start lower by 1/360 times the pitch of the radii (imagine the radii are like a screw). Repeat 359 times.

This was done on a Centroid CNC controller which has a bunch of capabilities that you won't find on the CNC routers that Woodcraft, Rockler and others sell. You could do it by manually rotating the part using an index wheel on those type routers. Centroid makes their Acorn controller retrofit specifically for retrofitting to homemade CNC's (homemade CNC's are getting to be common). For around $500 the Acorn controller could be put on one of the small CNC routers from Woodcraft, etc to expand the capabilities. Youtube and several forums are full of information on adapting the Acorn to various machines including lathes.

This whole CNC stuff is no more rocket science than hand turning is. Both have a learning curve. Learning to use CNC's has a bit of advantage over learning to hand turn because school districts are eliminating shop classes for budget reasons (that's too bad). But they're teaching what they call "coding" to 3rd graders. My grandkids were surprised to see I used coding to control CNC's.

If you like hand turning go for it. The end result is most important. You can make just as gawd-awful stuff whether by hand or CNC. Design is the most important thing. This forum has become a tool forum, "what's the best lathe" and so on. Not enough emphasis on design.

 

[Bill Blasic]

If you think you have an interest in CNC it is important to know that the machine itself is as easy to learn as learning your lathe. Its later after you know how to use the machine where the learning comes in as to how you make the machine do what you want it to. Learning how to use the software that makes the machine do what you want it to do is the most important and that my friend is where the rubber meets the road. That be like teaching someone how to turn on the computer and then have them open Photoshop and say go to work. I have one of those machines that Doug mentions above sold at Rockler and I have the 4th axis setup that came with it. Once I learn the Vetric software that came with it I'm sure I could duplicate Doug's part using that 4th axis (the fourth axis rotates the part in conjunction to the Right/Left, In/Out and Up/Down movements of the machine). This darn near 78 year old brain of mine said WHOA you got to be kidding! Luckily there is a young man who knows this Vetric software in and out and he sells a course that makes it easier to learn which I am doing. I did not get this to start a CNC thing, I bought to use in conjunction with my woodturning. Just like tools for burning or piercing etc. adding to your work (which of course led to buying a 3D printer to make things adaptable to woodturning and CNC). You know it's a great time to be alive, so much stuff so little time

 

[Brian Gustin]

You know it's a great time to be alive, so much stuff so little time

Yep... also a great time to be wealthy enough to be able to afford those "toys".. Thankfully wood turning is not a "rich man's game" -(like polo) so those of us that can't go buying tools willy-nilly when the mood strikes can still turn out beautifully crafted stuff, albeit with a great deal more effort (and skills honed) - which leads in to where my opinion comes from way back in that ol' debate that CNC work just ain't turning, in and of itself.

This forum has become a tool forum, "what's the best lathe" and so on. Not enough emphasis on design.

I'd beg to differ- I'm one of those that goes to "new posts" daily and reads every single posting, whether the title interests me or not (Typically about 20-30 a day) and my impression is a lot of it is form, function, and style (plenty of design ideas that may often lead to something new and different) While there may be frequent (and IMHO un-necessary) posts as to which is the "best" tool to get (If folks would utilize the search feature, those posts could be cut way back) , overall to me, most of the forum is about form, function, design, technique, and I greatly enjoy (MOST DAYS) the majority of the posts I go through. (Although some threads can be hard to follow when same author responds to each and every post one after the other with the reply button)

As for the original posting, I am among those that sees not a lot of value in the tool - majority of my arcs are not going to be a continuous radius , but instead closer to (but not exactly) parabolic (I'd guess closest would be to call it a curved J?) , which the tru-arc could not achieve, right? Tru-Arc might be about as useful as a sphere jig - both of interest to a somewhat limited sub-set of turners, and a sort of limited one-trick pony tool, I would imagine.

 

[Mark Jundanian]

Wouldn't it be an interesting evolution if Robust could morph the Tru-Arc into the "Tru-Curve" that could create various parabolic, elliptical and even hyperbolic curves.

 

[hockenbery]

Wouldn't it be an interesting evolution if Robust could morph the Tru-Arc into the "Tru-Curve" that could create various parabolic, elliptical and even hyperbolic curves.

That would be interesting.
While useful for some it’s sort of solving a problem that doesn’t exist for the intermediate and advanced turners.

Once we learn to turn by pivoting the body we can turn a decent arc.
When we learn to advance the tool over the rest as we pivot we can turn curves we want.

Of course engineers love to make things and that is their fun domain
Me - turning curves is my fun domain

 

[Doug Rasmussen]

Wouldn't it be an interesting evolution if Robust could morph the Tru-Arc into the "Tru-Curve" that could create various parabolic, elliptical and even hyperbolic curves.

That's been done for years. Lathes to do those are variously called copy and tracer lathes. A flat pattern is made of the profile and some sort of traveling tool like on a metal lathe is guided by the pattern to duplicate the pattern's profile. Pattern maker's wood lathe could do that with the correct setup. At the low end of the price and quality market tracers adaptable to most any wood lathe are currently available. But the ones I've seen suffer from lack of rigidity as I think the Tru-Arc may (rigidity comes at a high price).

Experienced hand turners can get pretty good at creating desired profiles. Your hand is a good judge of discontinuities in what you want to be a smooth contour, auto body repair guys use their hands to verify body panel smoothness. Where you get into problems in hand turning is where you use that tool called sandpaper to correct discontinuities. An ogee is a major problem getting two curves to be tangential at a meeting point. That usually involves sanding to create the tangency. Sanding can result in the two curves having a third curve to create tangency between the original two. As Odie mentioned recently the needed sanding can destroy fine design detail.

 

[robo hippy]

I will never understand the concept of 4, 5, or 6 axis machines. Coming from an aviation back ground, there are only 3, roll, pitch, and yaw. All the other so called axis are combinations of these....

robo hippy

 

[Darryl Fective]

I will never understand the concept of 4, 5, or 6 axis machines. Coming from an aviation back ground, there are only 3, roll, pitch, and yaw. All the other so called axis are combinations of these....

robo hippy

The x, y, and z are the 3 obvious ones, but I'd guess rotation and tilting of both the part and the cutter head add 4 more. (and extra levels of complication for programming)

 

[Kevin Jenness]

Kevin,

It's just a matter of repeating a number of times the same relatively simple cutter path.

First position the cutter at the top of the part. Plunge down cutting the three radii. Move the cutter back to the top of the part. Do an axis rotation, in this case I used 1 degree rotation. The part doesn't actually rotate, but the controller adjusts the next cutter path as if there was rotation. Position the cutter's next start lower by 1/360 times the pitch of the radii (imagine the radii are like a screw). Repeat 359 times.

This was done on a Centroid CNC controller which has a bunch of capabilities that you won't find on the CNC routers that Woodcraft, Rockler and others sell. You could do it by manually rotating the part using an index wheel on those type routers. Centroid makes their Acorn controller retrofit specifically for retrofitting to homemade CNC's (homemade CNC's are getting to be common). For around $500 the Acorn controller could be put on one of the small CNC routers from Woodcraft, etc to expand the capabilities. Youtube and several forums are full of information on adapting the Acorn to various machines including lathes.

This whole CNC stuff is no more rocket science than hand turning is. Both have a learning curve. Learning to use CNC's has a bit of advantage over learning to hand turn because school districts are eliminating shop classes for budget reasons (that's too bad). But they're teaching what they call "coding" to 3rd graders. My grandkids were surprised to see I used coding to control CNC's.

If you like hand turning go for it. The end result is most important. You can make just as gawd-awful stuff whether by hand or CNC. Design is the most important thing. This forum has become a tool forum, "what's the best lathe" and so on. Not enough emphasis on design.

The work I am doing would definitely lend itself to cnc methods, as it requires a great deal of hand carving and cleanup the way I do it. It would require a machine with a fairly large capacity- the largest piece I have done so far started with a blank about 7" x 11" x 18". The blank dimensions don't accurately define the machining envelope because of the several axes involved.

I am not completely ignorant of cnc work, as I have had a flatbed cnc router for about 8 years mainly (sporadically) doing flat and moulding work. I have a Camaster machine using WINCNC. I think the designs I have been making could be done on a large milling machine with some development of fixturing for inverting the pieces, or perhaps on a 5 axis router. A typical flatbed router with a large swing fourth axis "lathe" and a high gantry could accurately mill most of the shapes but would have to be combined with handwork for undercuts.

I agree that design is (at least) as important as technique. I find both explored in depth in this forum, thankfully so. When it comes to making pieces that require more than standard turning tools and practices it is useful to exchange ideas. At this point I am exploring multi-axis hollow forms that, without a major investment in equipment and modeling skills beyond what I have now, are achievable with a lathe and hand tools. I will post a few in-process photos in hopes that you can suggest another approach.

I am still not clear on whether you used a cnc lathe or a milling machine for the piece you posted. Can you do undercuts with the methods you use?

 

[Richard Coers]

The x, y, and z are the 3 obvious ones, but I'd guess rotation and tilting of both the part and the cutter head add 4 more. (and extra levels of complication for programming)

With a 5 axis machine, you get the standard 3, but then you can rotate the spindle to be parallel to the bed and then have the 3 axis again. And as you say, you can get them all at the same time. I machined a lot of full scale cab dashboards and consoles from rigid urethane foam for operators to test the feel in a full size cab. You get positive and negative under cuts in a single material clamping.

 

[Kevin Jenness]

I will never understand the concept of 4, 5, or 6 axis machines. Coming from an aviation back ground, there are only 3, roll, pitch, and yaw. All the other so called axis are combinations of these....

robo hippy

As I understand it, 4th axis cnc routers are typically flatbed 3 axis machines with an auxiliary "lathe" aligned with the long (Y) horizontal axis. The lathe rotates slowly as the gantry mounted cutterhead machines the blanks using the basic XYZ movements. 5 axis machines allow the cutterhead to rotate around and pivot from the vertical axis, allowing for more flexibility in defining complex shapes.
4th axis router
handrail milling
5 axis router

 

[Kent Reisdorph]

This forum has become a tool forum, "what's the best lathe" and so on. Not enough emphasis on design.

That's easy enough to change. Start some threads on design.

 

[Doug Rasmussen]

That's easy enough to change. Start some threads on design.

Yeah, easier said than done. Design is a weak point for me.

I went back to my college being an alum I was hoping to take a design course in the art department at a reduced tuition which they had offered forever. Nope, not offering that anymore, full tuition at big bucks.

 

[robo hippy]

I attribute all of the different multi axis machines to marketing. Even if you have 2 machines, they both operate on the 3 axis system....

robo hippy

 

[hockenbery]

I attribute all of the different multi axis machines to marketing. Even if you have 2 machines, they both operate on the 3 axis system....

robo hippy

There are only 3 Axis in defining points in space

I think the CNC makers use axis to reference motion or cut types
3 are the straight cuts/ movement in the x, y, and z directions or (left-right, forward- back, up-down-depth)
That’s close to the 3 axis we think about.

When the cutter can rotate up-down, and left-right they add axis
It makes some sense to use the movement capablitlites as additional axis

 

[Doug Rasmussen]

I attribute all of the different multi axis machines to marketing. Even if you have 2 machines, they both operate on the 3 axis system....

Not sure I understand your reasoning. My 4 axis mill has the usual X-Y-Z plus the 4th axis in line with the x axis to rotate the work. The 4th axis could be bolted on inline with any of the usual 3 axes. Nothing to do with marketing, the 4th axis is needed to do certain types of work. And it comes with a price tag, partly for the hardware then quite a bit more for software that supports the 4th axis motion. In my case the only marketing involved was the software company trying to oversell my needs in software.

As you go beyond 4 axes the price goes up exponentially. A good friend's 50 employee business makes high end guitar parts, their 5 axis machine to make guitar necks was $800K.

 

[Kevin Jenness]

I attribute all of the different multi axis machines to marketing. Even if you have 2 machines, they both operate on the 3 axis system....

robo hippy

That's not even wrong. With a 3 axis machine the cutting tool's orientation is fixed and it can move in x, y and z relative to the work. A 4th axis machine adds an axis of rotation to the workpiece. A 5 axis machine allows the tool orientation to rotate in two axes. A six axis robotic arm can rotate the whole machine on its base. You could add a "lathe" for rotating the work to a 3, 5 or 6 axis machine. There may well be other types of multi-axis machines and nomenclature and they all will have their marketing hype but having more ways to orient the tool to the work makes for more versatility.

6 axis robotic arm

 

[Richard Coers]

Not sure I understand your reasoning. My 4 axis mill has the usual X-Y-Z plus the 4th axis in line with the x axis to rotate the work. The 4th axis could be bolted on inline with any of the usual 3 axes. Nothing to do with marketing, the 4th axis is needed to do certain types of work. And it comes with a price tag, partly for the hardware then quite a bit more for software that supports the 4th axis motion. In my case the only marketing involved was the software company trying to oversell my needs in software.

As you go beyond 4 axes the price goes up exponentially. A good friend's 50 employee business makes high end guitar parts, their 5 axis machine to make guitar necks was $800K.

What is the advantage of a 5 axis on guitar necks? No undercuts that I know of. If there are, a simple rotary 4th axis should work well.

 

[Doug Rasmussen]

What is the advantage of a 5 axis on guitar necks? No undercuts that I know of. If there are, a simple rotary 4th axis should work well.

I made a mistake on the price of their machine. It was priced at $800K. They went to Japan and somehow got it for $400K (possibly it was a demo machine).

I don't know all the reasoning for the 5 axis. The brand is known for high speed wood cutting, high rpm spindle fast axis movements, fast tool changes, it might be used for other parts too? Who knows? They aren't dummies.

 

[Gabriel Hoff]

I made a mistake on the price of their machine. It was priced at $800K. They went to Japan and somehow got it for $400K (possibly it was a demo machine).

$800K??? Is that right?

 

[Bill Blasic]

If you have an interest in CNC, GRBL controlled machines start as low as $159 on Amazon. Now granted you're not going to be cutting huge things or doing them super fast but they work and give you an insight to CNC workings. My first was one of these low priced machines and I was truly shocked at how accurately they cut (The one I got could cut or use a laser). Yes that is a far cry from the Shark HD510 right at $4000 but that's where it could lead (the Shark can also use a laser). Like I said it is a great time to be alive!

 

[robo hippy]

I would expect the use of a multi axis machine for guitar necks would be in making a neck that has a different radius at the nut and another flatter radius where it meets the body of the guitar. I do have some of those as well as an underside neck that is not a straight radius, but off set to the thumb side which fits my hands better. Closet player only, but I like nice toys....

robo hippy

 

[Bill Alston]

I believe my first Dental Crown over 20 years ago was made on a four axis machine. The Dentist invited me to watch it being made