Unofficial CNC + CAD/CAM Discussion Thread

Hey guys. I wanted to start up a thread for those of us who are either deep into CNC shaping, or looking in to getting our feet wet.

Myself, I have experience with 5 Axis Thermwood CNC at work. I just completed the 5 Axis Thermwood training at their facility last week. Now back at work, everything has kind of been put on hold, and the aerospace company I work for is letting this machine just kinda sit idle until March I guess. So in passing with the Boss, I asked if I could ‘play’ around with it, and so far I have the green light. I’m curious about setting up this bad boy to cut out some shapes.

First things first. 1.) I need to find the best tool [or router bit] to use in the Thermwood. 2.) I will have to make some sort of Fence to hold the board in place on an elevated table or jig. It’s a big machine, and a long way down for the Z axis to the bottom of the table, so I will have to compensate with some elevation to hold a tighter tolerance.

Anyone know where to pick up a good router tool?

Hope everyone makes good use of this thread.


Ah! Good old TD bringing the new threads.

I am seriously considering building a small pantograph type of machine to do general templates.

Especially for things like copying rocker.

Of course if I could figure out how to hook up a drive mechanism that would follow a computer guide…well…

I would LOVE to come up with a HOME MADE CNC. You know…built out of 2x4’s, plywood and Home Depot hardware.

OK bro…it’s up to you and me! ROFLMAO


I would LOVE to come up with a HOME MADE CNC. You know…built out of 2x4’s, plywood and Home Depot hardware.

That might not be as crazy as you think. Or maybe it is, but still it’s possible. Check out f.ex.

Jonas have built one simple yet very impressive CNC machine himself in a surprisingly short period of time. While it may not be the fastest nor the most robust surfboard shaping machine out there, it certainly does the job and does it well especially for a DIY machine. Some pictures can be found here

Hi Tyson,

What a great opportunity you have! I’ve been around CNC surfboard design (not scanning) and cutting for

some time now. Having built from the ground-up has helped me understand some of the problems you may

encounter with milling a blank.

Registering the blank is more difficult than it seems. Depending upon the quality of the end result you may

want to have extensive support for the blank. Flex of the overall blank can make a milled blank deviate

noticibly from the intended design. By having enough good supports I am able to have accuracy well below

20-thousandths of an inch across 11 feet or so.

Another flex issue is the movement of the foam right at the cutting site. Turns out most cutting heads will

flex the foam whilst cutting, this deviation is seen a bit during some of the outline cuts and tucked rails.

The one advantage you will have with the 5-axis is your top/bottom registration can be made into a non-issue.

Programs like Shape3d have a 4th axis option to allow for rotation about the y-axis (length along the board)

which lets a cutting head cut the deck AND the tuck-under in one fixturing. Most cutting machines will have

issues with matching the top and bottom cuts (shifting to the left or right) and even a shift of 10-thousandths

is compounded by the flipping of the blank for the other side.

If you use 4 axes, you can cut your deck and tuck the rails, and the bottom cut can be done without any

tuck, so this leaves you open to do the bottom SLIGHTLY wider than the actual board, for example an 18-1/2"

wide board will have a bottom program 18-3/4" to cover for any shifts (most likely any shifts would be tiny)

Cutting head geometry can be a deal-breaker. I’ve done consulting for some of the bigger board cutting companies

and have seen many attempts to get the tool head shape right. For the big production guys, the bigger the head

the better, to get the number of tool paths minimized, but to NOT loose too much resolution. Since you will be

doing a smaller number of boards and cut time is not an issue, you can use a smaller cutter (still with two radiuses

on it) and increase the number of cuts per side. With enough cuts you can get a shape that requires very little

finish shaping.

The motors for cutting are typically higher quality, for example we use spindles which cost $5k+ and we run two of

them. Routers may work for low numbers, I would select high-horsepower/torque, like Porter-Cable 3.5hp with 5/8

collets. Rpm and heat-generation will be something to consider, depending upon the foam you want to cut.

Have Fun!


…hey George still too much trouble and cost to obtain results that are not so far from what a competent shaper can do

so is not better yet to find a pro cool shaper who knows the trade to shape the blanks?

and I still think that are enough truly good shapers to keep the demand going

(at least for surfers)

I don’t believe the thought is a CNC router is out to replace the skill of hand shapers, but rather for production.

For now, I’m just playing around with this, because I have the opportunity and resources available.

Reverb, the operative word here is competent, now you all know I never bag on the shaper who is learning the craft, I was a kook shaper once.

But, there are not many shapers who can consistantly recreate the same board over again and again.

The shaping machine is way out of my league to own one and I do own a very few programs. Machine cut blanks are more expensive that a hand shaped one and many times rather than wait for cycle time for just a onesy-twosey, I hand shape it.

I did a SWT II for a customer, the first of that design, I planned on getting it scanned, but lam’s didn’t show and it was rapidly aproaching when the customer wanted the board.

I had top and bottom rocker templates, outline temp’s with dimensions also, rail contour templates.

I was afraid to start the next one, as the original was soooooo spot on to what I wanted for this design.

I shaped one, the rails were fuller than the original, I did a second and although it was shorter and this distorted the plan shape, I was satisfied with the overall result (this one is for me).

So to get the same results over and over is a crap shoot at best, even for a competent shaper.

…Jim, I understand your point

yes, I know that to replicate an idea a machine is better

I forgot to put that in the previous comment

but not all the customers in the world are too pricky to check and see 1mm less in the shape of a rail…


Many shapers are never satified with a computer generated file unless it’s from a scan of the orginal board!

A serious surfer will get three exact boards made and if one has a rail slightly thicker that another it is rejected.

I guess it depends on you clientele?

If you have a model that you handshape and it’s the perfect magic carpet it would be sad not to scan it and convert it into a shape 3D file then having George cut it for you or one of the professional cutting services that are abundant down your way. Neptune; Rough House; KKL; Pearson; PlusONE so many I don’t think there’s a waiting list to have boards cut?

I know you make some really killer boards and it’s sad if you don’t have them on file for when your hands are crippled or you have respiratory issues.

With all your models recorded you can contiue to stoke out surfers with your dream shapes. Let say you have a 5’10 HPSB recorded and a 18 year old just rips on the board.

Then one of your older friends in his 30’s that still rides a shortboard wants the same exact board at 6’3. The program will resize your orginal model and your friend will be stoked out of his mind. Is that so wrong? You won’t need to re-template. You will have more time to surf.

CNC is not as easy as you may think? It takes a lot of skill. George at Plus One is one of the best in the business so I respect his accessment.

I work with a lot of famous shapers who can hand shape with a blind fold on. They all have there boards recorded. The finish product is the goal.

You still need design skills to make killer boards. The computer does’nt design them for you, you do!

Is Dick Brewer (70 years) old less of a shaper because all of his models are recorded? He can still out shape most guys on the planet from scratch however has some of the boards cut to keep up with demand. Pat Rawson; Rusty; Gary Linden; Timmy Patterson all have their boards on a program and anyone of them can shape a board from start to finish better than most.

Last time I checked every surfer on the ASP (WCT or WQS) get all their boards off a cnc file.

It’s better to go surfing on a warm summer day than spending 12 hours in a dusty shaping bay when everyone is surfing!

Where’s the glory in that?



CNC Machines are a must for production work and now the software for them has made modifying an existing designs foil, outline and rocker a reality instead of just stretching or shrinking the X and Y dimensions of the tool paths for length and width and moving the deck and bottom tool paths apart or closer for thickness.

One of things that’s hard to get around is who finish sands the machined blank. I’ve seen a lot of blanks from companies that use a stable of ghost “groove smoothers” to finish their blanks and there is quite a bit of variation from one to another of the same CNC cut.

Another thing I see quite a bit, is the blank not being properly centered and aligned, be it from lack of attention from the guy that places it on the holding system before milling or just that the stringer has a bow in it. This results with the board being wider on one side.

First of all, a big thanks to all of you for the very well thought out replys.


Would you be able to point me in the right direction to get the right ‘tool’ / router bit to shape foam that would fit a Thermwood? Where do you go to do your shopping? :slight_smile:

Also… BoardCAD doesn’t have the G code end of things together yet? What do I use to make the transition from design to the machine? I can’t really afford the hefty price tag on S3D.

Thanks again guys!

You will need a machine file to make the cutting path.

Hi Tyson, (sorry longwinded response, typical me)

As SurfDing said you will need to convert your design files to an appropriate machine

language. Conversions from BoardCad to .dxf or G-code are possible, you may have

those available within your company, in fact I would be very surprised if they did not.

Once you find a robust CNC program at work, your job will be to find its’ “import” capabilites

to bring in your BCad file.

There are several Surfboard design programs out there and most of them are available

as two types. The first type is a design-only version, and the other is a design/CNC

version. The latter typically comes with a hefty price tag. There may be places out

there with relaxed-enough policies to do a conversion for you.

Sounds like your company mills wooden products??? If it is a large firm you may be

able to get one of the on-site machinists to make a cutter for you. If not, there

would certainly be a vendor that visits your shop and they would give you the best

price on a custom cutting head.

Custom cutters we use on foam look nothing like the ones for wood. Ours look like a

small “top” with tungsten-carbide spikes all over it- no blades. The bits your company

uses are most likely bladed ones, and it would not be hard to modify an existing bit

to cut a board. My recommendation would be to use a straight-flute bit, 3"+ long

cutting length, 3/4" diameter. The end could be modified to cut as well. If this is

possible I suggest rounded end of about 4" to 5" radius with another radius transitioning

the end to the straight part, about 1/4" radius. If you have a shop foreman, they can

sharpen/modify bits for you. (BTW, our bits are spendy, you’re looking at $600 each

with a minimum order of 4)

If you will be machining with more the 3 axes, then the design of the cutter will be different

most likely egg-shaped or a sphere.

With all that said, I collaborated with an Aussie shaper/designer who had success using

a large twist drill, with the end ground to shape.

Keep pursuing this, you will learn a lot, which is a positive thing. It is too bad there are

still shapers out there who do not realize just how good milled designs have become.

I have been hand-shaping for 30+ years, no “rookie” who jumped onto a machine, and

I see the newest generation of shaping machines as “intelligent planers” in which I express

my “direct will” into the blank. I cannot find the words to describe how the designing of

boards has changed because of it. What I mean is, I can take a board that I’ve designed

and built from, change ONE thing, like rail tuck and run that board and test it. Been doing

this for 5 years steadily. And as Jim says, we’re pretty much tooled-up for “Onesy, Twosey”

style, as is most of our production. We primarily do custom shapes and we’ve never scanned

a board, (we don’t have a scanner) only designed virtually (there is a huge difference in file

quality with that alone) We now have many “magic” boards on file, created this way, and

have re-created them with much success. We also know what visual cues to look for in

the 3-dimensional design mode (wire mesh model) to get curves aesthetically right and pleasing

to the mind.

I hand shaped just a couple of weeks ago to salvage a blank that could not be fixtured in our

machine, I must admit, it was fun, and “I still got it” ha ha! Almost as much fun as designing on

my laptop! Heck I wouldn’t mind shaping a piece of wood with a seashell, if the conditions called

for it!!! ha! I got pretty close to what the machine would do, but the age-old dilemma was still

there, I had to spend over an hour of muscle work, sweating it, just to get to the “rough” state,

then that last half hour where I need to be accurate after getting beat up. OUCH! In the old days,

I would alternate, roughing the next days’ batch after finishing the previous days’ batch. Now I

realize the “beatings” are not necessary and I can focus on projecting my will into the foam for

an exact result.

Let me tell you, as a man of experience in both hand and machine shaping, the potential that’s

always been there for CAD surf designs is beginning to really be utilized. I am seeing first-hand

the process of developing a design to levels of detail I could never have imagined just a few

years ago… …and the results are showing where it counts, in the water.

If you are lucky enough to do several boards, you may begin to get a feel for the PROCESS

of designing for milling, and evolving a design with unprecedented accuracy, it’s great!

Best of Luck!


…Surfding and George,

your points are very valids and may be you have a better overall view than me


the surfers are not perfect

the waves surfaces are not “perfect”

the riding is always with constant AOA s changing

the glass is not “perfect”

the blanks are not perfect

the materials are still the same (PU, PS, wood)

you dont even in need of a less than 1mm of perfection

I see everyday “imperfections” in stuff that is way bigger and expensive than surfboard (like Houses, cars, etc)

and no one complains about that

also very good surfers when arrive to order new boards, want a similar board

but if you duplicate exactly the same board over and over

in few boards you dont have more to change

so the guy go ahead to other shaper to find MAGIC


because is boring to find the same sensations over and over again

if you try to duplicate a board by hand is not possible like with the machine so may be some tiny dims here and there make the difference (good or bad)

and keep the things INTERESTING for the rider

if you have all the stuff scored the guy; I mean, all the guys included Slater for ex. go and try to find new sensations in other boards

also, less work for craftmen

and we are lost an art form in giant steps

what will happen when no more master shapers and crew build boards?

and with an extinction craft

no one wants want to spend the time to learn

the machine will rule so the owner of the corporations and the marketing

We also know what visual cues to look for in

the 3-dimensional design mode (wire mesh model) to get curves aesthetically right and pleasing

to the mind.


I agree with you on this concept. I have created many models from cyber space that are viable.

With customers who are so picky I find that scanning their boards gives the best dupication.

Many shapers that own Cad programs bring me files that are full of problems so they have to be corrected.

Sometimes I just fix them and don’t tell them it was bad because you don’t want to bruise any ego’s.

Having the ability to scan comes with a price. It cost as much as the machine for the feature.

Plan on 7 months of tweaking. Once you translate the scan into a cad program like Rhino, Solid Works or

Shape 3D count on a few hours of tweaking to make sure it’s perfect. We get really good dupications don’t

get me wrong. However in you case being able to make all your designs from scratch is a great gift.

I know some shapers in San Clemente that are world class and do it the same way you do. There’s really

only a hand full of shapers that are really up to speed like yourself. You don’t need to scan with your know how.

Scanning is Ideal for guy’s that want a copy of a board that have no cad experience to re-create it like you can.


I have a spare cutterhead - (brand new) I can sell you one for $500.00 -PM me for details.

Normally I wouldn’t sell one of my cutterheads. Over the last 3 years I have experiemented with different designs.

You can just experiement on your own or I can provide you a short cut? I keep about 5 cutterheads in stock to

save time in ordering. It takes about 4 weeks to have one made. I have cutter heads for different materials.

The one that I’m offering is for Foam (PU; XPS; EPS) like the one George described.



I have seen several shapers who landed work from the “Big Three”, they lasted a little over a week before no more work was sent their way.

“It’s off the machine, just blend the flats and screen the rails”, it is still shaping and that requires actually looking the blank over and correcting any minor foo-foo’s from the master.

But…the machine does not care how crooked the stringer is, the shape is still accurate side to side, the stringer is just an imaginary centerline.

Hank Byzak had done a master for Joel Tudor off one of Nat Youngs Keyo’s, after getting a test cut done, Steve Clark had a look at the blank and said it was 3/8" wider on one side.

I tried my best to explain the the board measured 3/8" wider but was infact the same width side to side, my reasoning fell on deaf ears.

Even after I brought in my chalkline and snapped a line down the middle and low and behold, it’s 3’8" off the stick, even then he still wasn’t convinced, it must have been smoke and mirrors.

I did a twin “s” curve for Ireland, no center cut, snapped a line before it went on the machine, it didn’t care.

Misloaded blanks will have a lip on one side, Procam ran a load for Donald of Model “T”'s, they all were offset, had to make the one rail match the other, Donald asked why the rails were thinner than the master, I told him he could have 2 sized rails if he liked, he prefered them, the same size

But.........the machine does not care how crooked the stringer is, the shape is still accurate side to side, the stringer is just an imaginary centerline.

Hank Byzak had done a master for Joel Tudor off one of Nat Youngs Keyo’s, after getting a test cut done, Steve Clark had a look at the blank and said it was 3/8" wider on one side.

I tried my best to explain the the board measured 3/8" wider but was infact the same width side to side, my reasoning fell on deaf ears.

Even after I brought in my chalkline and snapped a line down the middle and low and behold, it’s 3’8" off the stick, even then he still wasn’t convinced, it must have been smoke and mirrors.

Where I’ve seen a lot of this is when the pencil lines for the fin boxes are done, since most shapers measure out from the stringer instead of in from the rail. This becomes really obvious once the holes for the boxes are routed. If the stringer is not at true center, one box will be closer to the rail than the other. This really shows if there is a lap line on the bottom in the color work or the glass job. This isn’t something that only happens with CNC’ed blanks, I’ve also seen it some in quite a few handshapes.

Speaking of Hank and Steve, back when I was working at Channin, I pestered Tony about this issue. I told him if the shapers routed the box holes, it would instantly become obvious to them why the should measure in from the rail. That didn’t go over too well with them, since it was another thing they would have to do that most likely Tony wasn’t about to pay them for.

I have only limited experience with the cutting process and I have already witnessed this happen.

One side being wider off the stringer than the other.

I actually spent an hour or so on one blank trying to even out the sides, and once done, trying to blend the deck and rail to match.

If you are a stickler about that kind of thing it can be quite difficult because the entire volume of one side is completely off.

The only way to fix it is to completely alter the overall size and design.

Theoretically, it seems it would also throw off the balance of the board and the intended “sweet spot”

Just my 1.874 cents

I got a couple of 11 footers cut by Walker on his “machine”, at the moment of cutting the boards were fine, but as the days went by the blank began making a left turn.

Now it was not a weany stringered blank, T-band center with 1/8" offsets, but is was cut from one of Harolds 12 foot billet blanks, each half poured individually.

The halves were post curing at different rates and one side was winning out.

It was becoming a giant boomerang, I had finish shaped it and put it in the vertical racks until I had more of them finished for the glass shop had not looked at it.

At first glimpse, you do not notice anything is amiss, but when I laid down the jig for marking the side boxes it would not mark the same for each side.

it was then I noticed that the center stick and whole board followed the same bend.

I have a 12 foot aluminum straight edge, when it was centered down the middle of the tail for the center box, that line pointed about 10-11 inches out from center.

No amount of opaque lam or graffiti/tribal art could mask this disaster, they went back to Walker and the wood chipper.

When I had my own glass shop, a “pal” brought in a shape he had done out of a small polyurethane sailboard blank.

It was for “our” accountant, I had previously shaped one for him from the same blank.

It was a real big guy tri, but centered on the blank gave a decent performing board.

“Pal” brought his version to me to glass, it had been pushed up into the tip of the nose rocker, on the bottom with the extra thickness, the nose curve falls much further back. So the board was all nose rocker, but that was not even the crux of the matter.

When it was time to route side boxes, the jig was so much closer to the rail on one side than the other. I stole a 1/8" here and added a 1/4" there and got them very close to the same distance from the rail.

The very next swell there he was with board in hand at the factory, said Bernie hated the board and I got the fins all wrong and that was why it rode like shit.

No amount of explaining took any of the blame away from me ( I kept it strictly about the fins never brought up the thought that it was a water pusher)

That’s a great summary of the issues I’ve experienced.

I concluded after 5 years that I was not going to get adequate results from machines in surfboard cutting services, so I’ve moved to a commercial service and 5 axis machine. Most of the issues have disappeared. I get 99% finished cuts (no ridges to sand off or mis cut rails to sorrect). .

More generally to the thread:

I highly recommend using a full fledged CAD program to check output from the surfboard CAD softwares. Rhino is possibly the best value for money (free trial is unlimited if you don’t save files but simply use the software for 3d rendering). Helped me to find errors that were below the tolerance of the surfboard software (a slice control point 0.01" out of line, for instance) that you wouldn’t see in a typical 64 pass cut, and would probably sand out, but could potentially cause some issues with concaves etc.

Hint: Take a look closely at the tail and tips of surfboard CAD programs in Rhino. You might find wierd (1/8" tall) ridges that result from the software trying to cope with joining too many complex surfaces. Winkles like this can perpetuate down the board and leave you wondering why the cut doesn’t look like the original smooth design. I also use a 3" nose and tail slice to help control the way the rails converge at the tip and to help flow lines smooth towards the centre. Without these slices the software often “cuts” the corner and my nose/tail rails end up wrong