aps3000 / aku accuracy

I’ve been using the Aku software on and off for some time now and I haven’t been able to get consistant results. I’ve had 7’1", 6’5" and 6’2" boards cut using the aku program on aps3000 machines. More often than not the nose and entry rocker is off, and the tail rocker is pretty close. The outline has been consistently good, but the foil for the front half is often thinner than the file is programmed. Concaves have been very good. The 6’5" boards have been the closest to the file while the 7’1" boards have been off the most. I’ve had files cut by 3 different machines and they all did the same thing. — So I’m wondering is this a flaw in the program that you have to figure out and compensate for ? or is it ‘operator error’ ? - I’d really like to hear other’s experiences with this.

Welcome to the world of computer shaping Patrick.


Having recently finished building a CNC machine, I’m going through
learning how to drive it. The below arises from this learning.

There is an adage that says, “no need for a stiff machine when cutting flexible materials”. Surf CNC machines are in the main built pretty lighly and this leaves some room for flexing during cutting.I don’t know what the specs are for the AKU, but I have no doubt that they are within industry standard, so this is an unlikely source of error.

It is more likely that the flexible material is the problem. Depending on how the machine is set up (blank support, cutting speed, cutting head, etc.) the blank is likely to respond differently. Sometimes the problem is the blank flexing away from the cutting head because of the direction of cut (power or climb cutting) or related to the speed of passes. The best boards I had cut commercially were cut across the Y axis instead of along the X.

You might find out what blanks are used and how your design fits into the blank. Sometimes blanks are tilted or shifted to fit the design, and this causes complications when it comes to figuring out how to flip the blank and cut the other side.



Let's don't go and expose the myth of all of them being perfect.

first of all, aku and APS are two very different machine now, not just ownership but the machine have both evolve in differerent directions.

the reason why you have problem is that the machine is probably set to cut to fast and the blanks flex.

tell your machine operator your problems, they should fix that because the machine can do insanely perfect board when setup properly.


How much off is it and in what direction? The rocker along the stringer is cut in one, slow pass so it seems weird that it’s off, but it might be caused by flex. Thickness might again be flex, but also adjustment of the supports or mismatch of paramters in the program with the machine setup or the blank file being wildly inaccurate. I would find it very hard to believe that there is an error in the calculations of the position of the board with them having a professor in mathematics on the team…

Thanks for the good info guys - I had an in depth conversation with a machine owner and it appears the software can be trusted when used properly and that more often than not problems come from machine setup, which is out of my hands - the fun never stops!

As a machine owner I have a question for you Patrick?

When you create a file do you order your blanks to match your deck rocker?

It’s best to send in your deck rocker to the blank company from your file.

Or do you use random rockered blanks?

With the wrong deck rocker in your blank would make it difficult to obtain the intended file foil.

If the thickness are off normally the operator has moved the fixturing towers to skin the blanks.

(Distortion is normally caused by manually moving the part or blank in your case)

This is assuming that your file is perfect?

Now having said that if your blanks are fitted and your files are flawless then it’s strange to have these out comes?

Kind regards,



i do know that with some machines if your not hosing it off with air often on the belts then the dust can build up and  cause the router to go deeper than normal but to have it happen at three different place seems a bit odd to me, and how much off are your boards from the program?

One 7’1" was off by more than 1/4" (plus) tail rocker, one 6’2" had tail rocker off by 3/16"(negative), entry rocker (one foot back) off by 3/16"(negative) on two 6’2" boards. Foil off in the front half on a few of them.

In my experience with pre shapes you pretty much get what you put into the file. Unless you’ve struck someone who really doesn’t know how to set up the blank to begin with.


Hi surfding,


could you go a little more into detail with this? I don’t understand why the rocker would be off with the blank since it’s cut from one side unless the blank flex or there is alot of internal stress in the blank. If the deck rocker is off from the blank you get deep cuts and a weak deck, but it shouldn’t affect the accuracy since the deck cut (which affect thickness/foil) position reference points are calculated with the other side already being cut. Or are you saying the operator missed the mark and cheated (moved the blank supports) to make sure he skinned the deck?



Haavard: I have cut 1000’s of blanks with my machine.

I don’t care if it’s a APS3000, AKU SHAPER, KKL, 3DM or SURF CAM machine.

They all have good controllers and the programs to run the GCODE are very accurate.

With the fixtures that support the blank once they are set should not be moved.

If the blanks deck rocker does not fit the board file the operator should just cut it like it is and just let it do it’s thing.

However the blank will be difficult to shape out if there is too much distortion.

So having said that the operator may have moved the fixture towers up or down to make the travel of the cutter head match the profile of the deck line.

If the deck was adjusted then the botttom will also need manipulation once the board is flip over to cut the remaining side.

Some cutting services will just cut the blank as it fits the fixtures.

If the blank does not match and it’s a miss cut the shaper has to pay and not the cutting service.

Now if the shaper buys the blank from the cutting service then if the cut does not match the intend file?

It now becomes the cutting houses problem.

If you supplied the blank and the rocker or thickness foil does not match the file then your at fault.


For this reason I don’t cut files from other people with random blanks.

One they take way too long to cut.

Two you get the blame for any distortion.

Prices are so cheap to cut a board as it is why spend more time struggling to put a square peg in a round hole?

I never got a response about the blanks?

I think it would be more educational to hear what 3 different cutting services have to say about the files provided and what blanks they had to work with?

If I had the original files I could put them into GCODE (Cutting File) and see if there might be some lines out of place or APEX not properly alined then we have another problem!

Kind regards,



I supplied the blanks for the first machine only. I operated that machine. One board (6’5") came out pretty close, the second (7’1") was off . All the others were blanks supplied by the machine owner.

Having used machine services for close to ten years and had my own now for almost five years I can safely say the machine is only as accurate as the operator/ maintainer. 

 There’s a couple things when the controller is set up matching it to the drives where machines can gain their “own personality” making each machine a little different. Then there’s the support and blade settings that can wildly change the thickness distribution and sizes.  Oh Maintenence or lack of cleaning and upkeep can play havoc with accuracy too!.. I’m lucky I have only one machine… The guys who have multiple machines here have so much fun trying to keep the three machines the same… But I would not trade my aps3000 for anything. It’s so good being able to control and get exactly what I want from a shape I design and cut myself…

Seems to me what is critically important is for the shaper/designer to have top and bottom rocker templates AND HOW THEY ALIGN TOGETHER TO ONE ANOTHER.

Keeping a formula consistent becomes demanding when resizing is desired.

How a shaper’s rocker stick reacts to APEX when centered at the bottom of a blank is directly related to portions of curve close to the 50% aka centerpoint that shaper’s rocker sticks are commonly positioned.

Rocker sticks are subject to GRAVITY as the rocker stick consists off MASS WEIGHT AND VOLUME where a mathematical tangent line on a computer is not. A surfboard program that measures about 59% forward from the tail compared to 50% differ. it can be argued that there are no differences that occur because the curve is the curve.I do not agree. A rocker stick will REACT to a curve flattened slightly forward of centerpoint causing the tangent line to shift reflecting greater tailrocker dims at the tail. The number changed due to this flattening of the curve at that particular point. Does it tell the entire story of what the rocker curve is? No.

**EDIT: The above isn’t clear. What I mean to say is that a rockers stick will physically react to subtle shifts in portions of bottom curve that may be missed with manual forms of mapping or whatever the proper term is. Obviously if a curve is correct it should not matter HOW or FROM WHICH POINT you use a tangent line to measure it; the numbers will reflect the position being measured from, but should be mathematically correct to reflect the same curve. **

The question then becomes how is my curve(s) being measured? Mapped? Scanned? Is the method performed manually subject to variation, or is my design scanned mechanically IN ITS TOTALITY so that the relationship of all compounding curves are kept intact. Compound curves are three dimnsional.

A challenge can be finding the apex of a curve as intended by the designer IN RELATION TO THE DECK ROCKER which the two together determines foil aka full length thickness flow and how that relates to the position of LOAD,  or RIDER.

Variables that result in changing the foil thickness or the bottom curve relative to the deck curve distorts the intent of the original design hence the riding characteristics of the designer.

I think in terms of 3 dimensional versus 2 dimensional.

For that reason my primary concerns in maintaing a design’s integrity and original intent deals with PITCH AND YAW.

These two terms most accurately describe the maneuvering characteristics of what a RIDER FEELS versus what the surfboard does while traveling along a wave face.

The first is how it feels, the second is how it looks.

Tilting a blank to cut a deckline rocker without regard to how it relates to the bottom curve is a glaring mistake to me as a designer. Other variables discussed here that can affect depth of cut changing distribution attributes to inaccuracies that can change a surfboard’s overall performance. Imagine a step deck deck being cut twice the depth of the intended design: that surfboard’s performance would differ from the original intent, or the tail thickness over the side fins of a tri fin being 25% thicker than intended in the design… this too, would affect the board in how it planes, and how it feels.

I have always wondered how registration is guaranteed when milling blanks. It seems there are more variables being discussed here that makes perfection still somewhat elusive.

I know people who have a hard time wrapping there mind around CNC and CAD.

That’s OK we still have Quakers in Pennsylvania.

My son and I worked on a new model for summer.

Once we had the design all clean up we grabbed a blank with fitted deck rocker.

The nice thing about a deck rocker that fits the design is that your cuts are very shallow.’

In fact It would be hard to believe you could skim the deck with an electric planner less than 1/32".

With a CNC machine and a fitted blank it’s quite easy to skim the deck extremely shallow.

This makes for a hard deck. (Referring to PU)

The luxury is having full control of the design and machining.

Kind regards,




Hi Ding,

I’m not sure what the Quakers quip is about, but as I have started to study this approach to designing and replicating surfboards I can see merit and pitfalls.

Since Shakespeare said “nothing is good nor bad, thinking merely makes it so”, I apply his logic to the CNC approach.

I readily see the abiity to accurately replicate a given design while mantaining integrity on the decks of machined blanks. That’s a huge plus for the consumer wanting the optimum strength to weight ratio.

I’m also a realist from the standpoint that the approach is performed by human beings that are subject to variatons in how they do their jobs…and milling surfboard blanks is a job.

The question that I raised wasn’t a jab at this part of our industry. It was merely a question regarding how a surfboard design is mapped, scanned… in this type of reverse engineering. The question is innocently asking how acurrate can the process be? How is it performed? I’d like to know, and I’m sure other people would too.

My own personal experience with a file is quite limited. I was told I would be supplied with a top and bottom rocker template with my first file, then never received one. To compound this, the sample cut was resized from the original board. However, I thought I would get the rocker templates from the original size so I could compare it to the board the file was created from and also future cut blanks.

That didn’t happen.

So my advice to shapers that are getting into having files made is to MAKE bottom and deck rocker templates from the board they want a file made from, THEN check it against the inital sample cut to see if it is what they submitted. I should have done this and it is my own fault for not doing so.

The more you know of your design going in, the better result you stand to achieve.

I’m not a Quaker, but I DO have some difficulty “wrapping my head” around how someone creating a file can put in compound curves of a sophisticated design at exactly the correct points. It has been impressed upon me that less control points produce cleaner cut blanks, but if there ae critically important design features being missed in setting up a file, the need for smooth cuts is overshadowed.And yes I am aware there are XYZ axis to input data.

I suppose as I study Shape 3D, I will get a better grasp of what is possible and fairly simple, and what is more challenging to achieve. Maybe then I can get out of this black and white Quakers outfit… the shoes are killng me!

The computer/CNC are only as good as the data going in, the quality of the materials used and the capabilities of the equipment doing the cutting.

It is my understanding that a quality CNC set-up can shape within 2.0 mm tolerance/variance from board-to-board.  I doubt a human shaper could do that day-in day-out: especially factoring in hangovers, the flu, migraine headaches, etc.

With CNC, surfboard shapes and designs are limited only by the designer’s imagination and computer/CAD/CNC skills.

I still have great respect for the hand shaper/sculptor.  But if I was making surfboards commercially, I’d be using CNC shaping.