The positives for the Spline model is all being milled in aluminium.

Aluminium is a very good material to mill and polish to a high finish grade.

Jan is doing the CAM programming in Unigraphichs NX , and is milling the positives at either a Matsuura 800 CNC milling machine, or at a Makino V77 CNC milling machine at work.

This means the accuracy of the positives is very high , because this is really accurate machines , f.ex. the Makino is measuring the tool lenght with Laser, and also, all the way compensating for temperature differences.


We mill the positives with very fine steps, and after the milling we sand with 1200 wet paper , then 2000 wet paper, and at last we polish it with a polishing paste called "Autosol" , normaly used for polishing crome on motorbikes etc.

Then the aluminium gets a super high grade polished surface.



This is the Matsuura machine.


The Matsuura milling the small mould for the CFK linkages for the v-tail. (See the moulds page..)

This is the positive from the RaceM X-tail fuselage, just before remilling it to the Spline fuselage...

The left and right positives for the fuselage, they are not polished yet.

At the end there will be mounted parts that forms the v-tail connection, see cadpictures on top of this side and the picture below..

The fuselage ends, rough milled at the Matsuura, and now ready to be finished at a Röders 500 5-axis millingmachine, that is perfect for milling the holes for the guidepins for the v-tails in the right angle and position. The Röders also offer 42000 RPM on the spindle making it perfect for milling with the small mills (down to Ř0,6 R0,3mm) at the small corners , especially at the cutout for the linkage cover.


Wing section on the fuselage.

Closer look, where it is clearly to see, that the flap will follow the shape of the fuselage from -5 to +15 degress. You might also notice the small marks for adjusting the flapsettings after.


V-tail positives , guess wich one is polished...

Yes , you where right, it was the left one..

Notice the small insert , that forms a groove in the GFK mould, where the homemade CFK linkages will fit exactly into , when they are glued in the v-tail before closing the v-tail moulds.


That means they will be in the same (right) position everytime making a v-tail.


Here you see the CFK linkages.


This is the positive for the top of the fuselage between the v-tails.

It is milled on a Röders RXP 500 5 axis machine, wich runs together with 3 other machines on a 16m long robot-line. (4 milling machines served by 1 robot travelling on rails), so it was put in the robotmagazine yesterday evening, and then it was finished this morning :-)

Notice the small marks, to adjust the rudders to zeropoint.

The V-tail-rudders are traveling along the fuse from -7 to +7 degrees, to prevent the air going around the end of the rudder.

Especially when giving up-elevator there will be a high pressure between the 2 v-tails, and when the end of the rudders then is lying close to the fuselage, the air has no other way to go, than over the trailing edges.... and not going around the end of the rudders, making  2 vortexes...



This is a screenshot from our 3D coordinatemeasurementmachine (CMM), where we measured the one positive for the V-tail (after polishing).

The measurements are in millimeters, so off all these points there is a max. deviation of 0.035 millimeters, and this is mainly because of the hand polishing, and that the Matsuura cnc-milling machine is about 10 years old , and have run about 35000 hours....

If you look at the points at the parting plane (no notes at these points) they are about 0.03-0.04millimeters in plus, but that is OK, because there will always be some epoxy between the 2 mouldhalfes, and we will not be able to screw the moulds so hard that there will be 0 between the 2 mouldhalfes....



John is waxing some moulds and positives.  We are using a wax called Mirror glaze 8, from Bacuplast.

And here is our first working accident, John cut his finger on the sharp edges on the positive for the fuselagepart between the V-tails, while he was waxing another mould.... (fortunatly he survived...)


Jan has been to Langeland (Denmark) on holiday, and had offcourse some Spline parts with for polishing.

The one morning Andrea (5 years) woke me up and said "come on daddy, we have to polish the aluminium now" , so we did before the breakfast, what a nice holiday.


She really likes to help :-)


Inserts for making the holes in the mould for the cores for the joiner holes and the connector holes is finished now.

Both Positives for the fuselage is polished , and just waiting for the endparts to be finished.

At the bottom of the picture you see some steel, that will be made for some supports/safety bars for the wing positives.


Closer look at the positives with the inserts mounted.

Left in the picture you also see one of the blocks that will make the parting plane for the root of the wingpositives. 

The positives has actually bended a lot (3-4mm) after the milling so we have screwed the positives on 2x  75x75mm bars of aluminium, to get them straight.

Now the positives for the fuse is only waiting for the last endparts. The first one is sitting in the magazine of the robotline with the Röders 5-axis machines , just waiting for all the "real" workpieces to be finished first.....


The first endpart for the fuselage positive has been milled.  But it is going in the milling machine again, because the stupid designer :-) made 2 surfaces non-tangent, so we are remilling this area to get the 2 surfaces more tanget to each other.

Here the nontangent surfaces can be seen at the right upper corner.

We are now started on preparing the Alu blocks for the wing positives.

The block for the 2 undersides for the wings, is glued/screwed together from 2 blocks sized 153 x 80 x 1550mm.

At the picture the first block is ready to get lifting holes and holes for screwing the 2 blocks together drilled.

Cutting M12 Threads for lifting the plates with Eyebolts.

The 2 blocks is ready to be glued/screwed together to one block for the wings underside positives.

We glue the blocks together with 24 hours epoxy, and tighten the 4 x M12 screws.


The Alu block for the upperside positives is also ready, with M12 lifting holes drilled also (no picture)


In each block we are going to mill both the left and the right wing positive at the upper and underside of the block, that means one block with both uppersides and one block with both undersides.


Here the 2 blocks for the undersides is glued together.

The 2 rails on this side is to get the 2 blocks as flush as possible at the one side.

Here the Support/safety bars for the wing positives is grinded to get as parallel as possible.


Jan has started on making CAM programming for milling of the wing positives in the CAM module of Unigraphics NX4.  As you maybe can see on the screenshot, the Makino can "only" travel 1200mm in the X-axis, and the positives are about 1550mm long, so we need to move the workpiece once to be able to mill it. 

The workpiece is turned around , and the rest of the positive is being roughmilled.

We will roughmill the blocks on both sides with a stock of 3mm , before we start the finish milling, because the aluminium will probably bend wenn roughing material of.

Simulation of rouging toolpaths in Unigraphics NX4

The endparts for the fuselage positives is finished milling, and the first is mounted and polished together with the main part of the positive.

Even after polishing together there is still a line where the two parts meet, but it will be polished away in the final moulds.  Notice the earlier mentioned non-tangent surfaces, they are now much better after remilling it.

This is the other part, not yet polished, for the right side of the fuselage. Notice the holes for the guidepins for the v-tail, they are also milled in the 5-axis Röders milling machine, so there angle and postion is very good, so they will fit the V-tails exactly :-)

All the small slots around the cavity, is made to be able to mill all the corners, and also to be able to polish "behind" the parting plane.  All these slots will be filled up before moulding over.

Both positives for the fuse is finished polishing

Also the parts that will build the parting line of the root sections on the wingpositives is finished.

This one is for the underside of the wing

And this one is for the uppersides of the wings.

Just tried to hold them together, so you can see how these will fit each others, one day when the moulds for the wings will be ready.

All the Support/Safety bars for the wing positives are finished.

The first block for the wingpositives is placed in the Makino milling machine.

The Makino is measuring the tool lenght with a laser.

Roughing with a Ř25mm R1.0 Pokolm special made for aluminium, depth 5mm sidestep 6mm , spindlespeed 10.000 RPM , Feedrate 15.000 mm/min.......  that is going very fast....

Video of roughmilling

Another video of roughmilling


Jan´s college Morten that helps us running the Makino, with the first side roughmilled.

Jan is looking at the first finnish milled area.....

And here you can see it....

The front of the wing is finnishmilled with a ř8.0 R1.0 mill, stepped 0,15mm sideway, and the backpart of the wing is stepped with 0,5mm , as it is much more flat.

Video of finnishmilling

Jan is happy, as it it his birthday, and getting a wingpositive for the Spline milled at ones birthday , is more or less the best birthday present one can get, or?

BTW in Denmark all calenders lool like the one behind.....


The positives don´t need much polishing with the gridpaper, that means less handwork=better precision...

The block for the uppersides is finished milling , and here are som pictures....

The part that makes the parting plane in the rootsection is testmounted.

Jan is sanding the wingpositive.  First with 1200 gridpaper , then 2000 gridpaper.

The 2000 gridpaper is first done in the span direction , then in the cord direction (as on the picture) and then in the span direction again. This is done to ensure that all the scratches from the 1200 paper is gone, everytime we change the direction, there should not be any crossgoing scratches any more, that means that the 2000 surface is "in bottom" of the 1200 surface. (nothing left of the 1200 sanding)


The positive with the finished 2000 surface.

and here it is finished polished with the "autosol" polishing pasta.


Nice surface :-)  , then I can turn it over and do the other side.....

The other side is also polished now, and all the cores for making all the holes in the mould is ready.

The core for the connectorhole.

The positive for the upperside is delivered to John.

The positive for the wing undersides is finished on the one side in the Makino milling machine.

The positive is finished on both sides, (Right wing underside on the one side, and the Left wing underside on the other side)

End view

The positive with the block making the parting plane at the rootsection.

Now we just have to make 2 threads in the endface, to be able to mount the partingplane-block, and then the polishing starts again.....

The rest of the family (Louise, Jakob and Andrea) has been on a scout camp saturday and sunday, so I had a lot of time for polishing, and when they got home I was almost finished with both sides, and Andrea immediately wanted to help with the last finish.....


Andrea polishing , and me eating the leftover of cake from the scouts camp......

The positive is now finished, and It will go to John in Odder tommorow.

New positives for the innercone, milled, not polished yet.


In the right side positive we added a Spline logo, milled in a depth of 0,3mm with a Ř0,5 R0,25 ball-end mill.

This is the two support blocks that is mounted underneath the fuselage positive.

We have added some clearence slots here to make space for the four steel blocks that we will use to connect the new innercone positive with the fuselage positive.

This is the 4 steelblocks used to connent the positives.



The Spline Team 2008