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New guy to forum, CNC woodturning..

D

Doug Rasmussen

Joined
Dec 5, 2015
Messages
911
Likes
444
Location
Seattle, WA
Hi all,

New to the AAW forum, long time reader of American Woodturner mag.

My interest for years has been the use of CNC machines in woodworking. We had a number of metal cutting CNC's in my business, with my semi-retirement a couple were kept for wood cutting/turning.

Any others here involved in CNC'ing their turnings? In the ornamental turning sub-group a few individuals use CNC machines. So much is going on in converting machines to CNC control it can be not much more expensive than good hand turning equipment.

Aside from the automation of the actual turning process, there is a major difference between hand turning and CNC turning. With the CNC you have to be more concerned initially with design. When hand turning many times my designs would evolve as the work progressed. With the CNC the design has to be locked in to begin programming the machine.

It's not all just pushing buttons. You still have to understand the grain of your blank and how best to cut it. The same design in different grain orientations needs different CNC programs. Then there's software and it's sometimes steep learning curve. The good news these days is the type software that cost thousands a few years back is free to hobbyists (Autodesk's Fusion 360, for example).

BTW: http://www.bloomberg.com/news/artic...castle-furniture-made-by-robots-costs-350-000

Doug
 
I guess understanding the setup and blank orientation could be considered a craft.......but the craft would be more of a machinist topic forum......
 
Another major issue with CNC turning is getting tooling with high shear angles. Often you see a router bit in the spindle, or a scraper bit used on CNC. You don't get the same quality as a skew or even a spindle gouge. You can get extreme shear angles with the V cutters like those used copy lathes, but really expensive.
 
Welcome Doug. I'm fascinated by CNC but don't have the money or computer skills to ever run one of those things. I'm always interested in the final piece of work, not how you got there. At least not from an artistic point of view. From a mechanical point of view I'm always interested because I love seeing how someone does it.
 
Doug -- there are several people using computer-assisted machinery for ornamental turning (to replace the complex analog machines of the past). The Ornamental Turners International web site (which is an AAW chapter) has a forum topic dedicated to computer-assisted work. The equipment is not the standard CNC machinery that is used for mass production. Instead, the machines are custom built to meet the unique requirements of ornamental turning and are intended for making one-of-a-kind artwork.

For more info, see http://www.ornamentalturners.info

Bill
 
Bill Boehme said:
Hi Doug. Welcome to the AAW forum. I would be interested in learning more about what you do.
Click to expand...

Bill, at this time mostly I'm experimenting with unusual shapes and decorating turnings using acrylics and pyrography. I uploaded some photos, but didn't realize they would be in the gallery where the work all looks first class.

The burl bowl is about 8" diameter, with the rigid of the CNC plus razor sharp tools there was no tear out or gouging. And, practically not sanding, just a quick pass over it with 400 grit.
 
Richard Coers said:
Another major issue with CNC turning is getting tooling with high shear angles. Often you see a router bit in the spindle, or a scraper bit used on CNC. You don't get the same quality as a skew or even a spindle gouge. You can get extreme shear angles with the V cutters like those used copy lathes, but really expensive.
Click to expand...

Richard, I'm not sure what you mean here. Most of my cutters are carbide insert type, the same as those we used for aluminum turning and milling. They're consider high positive rake with a razor sharp edge.

I've looked at the inserts supplied with carbide hand turning tools. Those are not positive rake with their flat top. That surprised me so I called one of the manufacturers to ask why. They said the high positive type have to much of a tendency to grab and gouge the work because they can't hold them rigidly enough.
 
john lucas said:
Welcome Doug. I'm fascinated by CNC but don't have the money or computer skills to ever run one of those things. I'm always interested in the final piece of work, not how you got there. At least not from an artistic point of view. From a mechanical point of view I'm always interested because I love seeing how someone does it.
Click to expand...

john, after having CNC machines for 25 years in my business I'm still fascinated watching them cut. Hobby grade machines capable of cutting wood are coming down fast. You could get a small one for less than the price of a Oneway lathe.
 
billooms said:
Doug -- there are several people using computer-assisted machinery for ornamental turning (to replace the complex analog machines of the past). The Ornamental Turners International web site (which is an AAW chapter) has a forum topic dedicated to computer-assisted work. The equipment is not the standard CNC machinery that is used for mass production. Instead, the machines are custom built to meet the unique requirements of ornamental turning and are intended for making one-of-a-kind artwork.

For more info, see http://www.ornamentalturners.info

Bill
Click to expand...

Bill, yes, I'm aware of the site and your contributions there.

In 2004 (or was it 2006?) I attended the Seattle area conference after a friend tipped me off to it. The night before I stayed up late doing small sample pieces for the instant gallery table. They got lots of interest leading to discussion over how they were done. The reactions were interesting to watch, when most of the experienced, long time ornamental turners heard CNC they dropped them like hot potatoes.

Do you sense what seems to be a lessening of interest in OT work?

Oh, almost forgot to mention the pyrography work . My first attempts were with the dedicated tools sold at Woodcraft, etc mounted on the CNC spindle. They don't work well with automation. Hot, but with no temperature regulation they can't maintain consistent marking. A digital Weller soldering iron set to max temp of 800F works very well maintaining an ever burn width. Best of all is the low power laser kit from J-Tech, $350. 2.8 watt max which is enough to mark wood at speed of around 5 to 10 inches per minute. You also have a focus range of 1/4" meaning you don't have to program exactly to a contour.
 
Doug......do you fabricate attachments for the pyro to cnc?????????????? curious as to what it looks like
 
welcome Doug,
I've used my CNC to rotary turn some pens where I leave the 3d model raised from the surface.
My real interest is in ornamental turning, so I'm in the process of adding a slide and cutting frame to the CNC.
I still love traditional turning, so there is still of manual turning I need to do before moving things over to the CNC
for the decorative work.

unfortunately (or not) the Christmas season is in full force so I'm just too swamped to work on the other things.
Maybe in the spring. ;-)
Cheers!

NDBDMjBGNDcyNERCODRFODMyREE6MDlmMTEyYzk0OWIyY2NhNzY4ODE4YzRhNzkwZDgwNDQ6Ojo6OjA=.jpeg
 
Doug Rasmussen said:
<snip> They got lots of interest leading to discussion over how they were done. The reactions were interesting to watch, when most of the experienced, long time ornamental turners heard CNC they dropped them like hot potatoes.

.....

Oh, almost forgot to mention the pyrography work .....
Click to expand...

This really takes me back. Get ready for some backlash. A tool is a tool in my book.
I once got thrown off a well known scroll saw website for using a laser to cut out my designs. Some look at my rotary turned pens and snub their noses at it because it isn't 'real' turning.
Like Bill, I'm making some jigs to do some similar OT work on my CNC. We'll see how it is received. I'm pointing this out because I've aways been in the forefront at using new technology
for traditional work. Lasers are pretty common place now in woodworking and turning, but in 2000 it was heresy. while common place now, I was using a dental tool to engrave work in 1996 and for more than just pierced work. In fact I demonstrated it at the San Antonio symposium in 1998. The reason I moved to the laser was that I had vision in my head that these hands could not simply do. The laser afforded me the opportunity to make my visions a reality. I refer to laser work as laser pyrography because it really does the same job. It can even do shading by altering the power levels on the fly. But although you get similar results you will always get criticism from traditionalist. Thats pretty much why I haven't participated in hobby groups in the last 15 years. Don't get me wrong - I learned first how to do things the traditional way before moving on to use nontraditional tools to do the work more efficiently and more accurately.
FOR ME - I love OT work, and see lots of similarities afforded by the CNC. A router takes the place of a drill frame. A 3d model with curves forces the router to move up and down which is similar to what a rose engine does when it follows a rosette. The pumping action is a different matter. I'm looking to add a universal cutting frame to mine to get some nice patterns as it moves
up and down following a 3d model rosette. Just don't let the backlash throw you. the only person I have to please is myself. And occasionally I get pleased when the customer pays the big bucks
iridamngardless of how I made it.
cheers!
-Nick S
 
Richard Coers said:
I'm talking about these kind of cutters.
http://www.profiledesigntooling.com/copy-lathe-cutters
Unless you are rubbing the bevel on the Hunter style of cutter, you won't get the same shear angle and surface quality of hand tools.
Click to expand...

Richard, here's a link to a cutter close to what I use in the milling machine. The turning cutters are similar with the same high positive rake cutting edge. The inserts are mirror polished with a razor sharp cutting edge. Shavings just roll off these. I can't imagine anything that would be better.

https://www.iscar.com/ecatalog/Ecat/datafile/PICTURE/1778.gif
 
Doug Rasmussen said:
Richard, here's a link to a cutter close to what I use in the milling machine. The turning cutters are similar with the same high positive rake cutting edge. The inserts are mirror polished with a razor sharp cutting edge. Shavings just roll off these. I can't imagine anything that would be better.

https://www.iscar.com/ecatalog/Ecat/datafile/PICTURE/1778.gif
Click to expand...

I'd like to see the holder, and what you are using. It doesn't look like you can get very tight into a bead or groove. No idea what your work looks like though.
 
Richard Coers said:
I'd like to see the holder, and what you are using. It doesn't look like you can get very tight into a bead or groove. No idea what your work looks like though.
Click to expand...

Richard, the holder for the referenced insert is basically a straight shank, so yes, I can not get into a tight place with that one. There so many shapes and varieties of inserts and holders anything is possible though. I only showed that one as an example of the high positive rake because it was the first picture I found.

The unicorn piece in the gallery wasn't a lathe part, it has sharp recesses. It was done standing the work vertically on a milling machine with a wing type slotting cutter with the tips reground to a 60 degree angle. The cutter is very much like those used in biscuit joiners.

Another factor in working with a CNC milling machine is you can do all your cutting with climb cuts, that makes a lot of difference in quality of finish. Most everything turners do can be done on the mill rather than the lathe, it just takes a bit longer. Non-round bowls are easy on the mill.
 
Doug,
I'm real familiar with CNC. I ran a 5 axis, 5'x10'x3' Z axis MotionMaster for 12 years in a model shop before retiring. I'll disagree that you can get any where close to the surface finish I can get with a skew or even a bowl gouge, with a rotary cutter. Even if you have no chip out, you'll always have some peaks from step over. A shear scrape with a hand tool will shine if done properly. You bet I could not turn any where near the shapes I could get off the CNC. But, I don't have to spend a day on the computer doing the elaborate surface generation in Rhino either.
 
Richard, given your experience I'm surprised you aren't more enthusiastic about CNC wood turning.

The peaks you mention, we always referred to them as scallop height. Most times the stepover is calculated to keep the height to less than .001". It helps to use as large diameter cutter as possible. A recent project was a concave tapered, twisted, fluted column using a 6" wheel cutter with a .020 stepover down the column. No noticeable stepover marks at all. Oh, and that column with it's variable radius flutes is something I know of no other way to economically do except by CNC

Never used Rhino, but it does take some time designing and coding in my CAD/CAM. Still, I bet I could do the CAD work and produce a finished piece in a fraction of the time a hand turner would take. The CAD/CAM work is something I enjoy.
 
Doug Rasmussen said:
Richard, given your experience I'm surprised you aren't more enthusiastic about CNC wood turning.

The peaks you mention, we always referred to them as scallop height. Most times the stepover is calculated to keep the height to less than .001". It helps to use as large diameter cutter as possible. A recent project was a concave tapered, twisted, fluted column using a 6" wheel cutter with a .020 stepover down the column. No noticeable stepover marks at all. Oh, and that column with it's variable radius flutes is something I know of no other way to economically do except by CNC

Never used Rhino, but it does take some time designing and coding in my CAD/CAM. Still, I bet I could do the CAD work and produce a finished piece in a fraction of the time a hand turner would take. The CAD/CAM work is something I enjoy.
Click to expand...

For me, woodturning has become a Zen process. It's about me and a chisel. My ability to guide the tool to produce the finest surface and form possible. I've built furniture for 40 years, using many fixtures, fences, and templates. My skill was in the design and the ability to machine wood to perfection. During that time I also sat on my butt at a computer, then on my butt watching a robot remove material. That chair time was the least enjoyment I ever had working wood. The creative part was manipulating the software. After that, a monkey could push the green button, and hit the red one when something went wrong. Sorry, no enthusiasm for the robot!
 
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