Alpine Snowboard Plate Systems

[Jack M]

Thank you @SunSurfer! 

I'm not surprised by either result.  Regarding stiffness, adding the plate would not make the board magically flex more in this static scenario.  The board now has to work against the friction of the plate.  I think people say an isolation plate like the Boiler or Apex makes the board feel softer because it does "free" the board from the rider, to be able to flex with far less resistance from the rider.  I have definitely felt that.  This test does not account for that. 

Regarding torsion, I think you would need to twist the board at or much closer to the inserts to see a difference.  I think what happened here is that the plate has simply moved the point at which the board starts twisting closer to the tail, but the relatively soft tail still allows for all the twist.  Like Beckman said, a big part of the function of the plate is reducing the rider's ability to twist the board.  This was an eye opener for me when I began my plate review on my Kessler 168, because previously I had only ever used a plate on a stiff NSR 185.  Suddenly not being able to twist the Kessler boosted edge hold - and made me realize I had been twisting it unintentionally.  This inspired an adjustment in technique which has paid off.

[BlueB]

6 hours ago, Corey said:

It appears as though you loaded the board in the middle of the insert pattern. That would artificially induce more flex in the un-plated condition than the loading induced by a rider. Moving the weights to two points on to the inserts (and closer to the axles) will reduce the difference, until the loads are right on the axles and then it's only friction in the sliders that would impact flex. 

This ^ is an error in the experiment. I think it would be worth repeating as Corey suggested. May I add that the 2 separate weight over axles should be used, to take the plate bend out equation, too?  

[BlueB]

It would also be worth repeating the twist experinent in two different ways: 

1) Clamp at the contact point of the nose, apply twist at the tail contact, with and without plate; 

2) Clamp right in front of front axle, apply twist just behind rear axle, with and without plate. 

[SunSurfer]

https://imgur.com/gallery/RLfeUJc

(photos link above)

Repeated the torsion experiment, applying torsion force only to the interaxle section of the board. Found the app setting that gives tenths of a degree readouts.

Summary: The Bomber Boiler plate 4mm exerts significant torsion resistance in the midsection between the axles.
With the plate in place and force applied the board twisted to 2.5 degrees inclination.
With the plate removed and no other changes, the board twisted to 4.4 degrees inclination.

@CoreyPhew! That's a relief.

Further flex testing to follow, in particular focused on where the mass is located.
 

[Corey]

Cool stuff Mr. SunSurfer!  It's comforting when measurements line up with expectations.  

Of course, it gets real interesting when they don't!  I'd rather be proven wrong than think I was right without data.  

[SunSurfer]

https://imgur.com/gallery/Ol3jIeo
(representative photos of the method)

The effect of a Bomber Boiler Plate 4mm (not Lite) / UPM on the flex of a Riot Supercarve snowboard under a static load of approx. 16kg.

Summary: The plate makes the board flex as if the 16kg load was equally divided and placed at the same point as the plate axles.

Method:
Snowboard mounted on 2 sawhorses/trestles, supported at each end of the effective edge, clamped at the tail end. The mid point of the designed pair of binding insert packs was determined and marked. A reference point approx vertical in both planes below this mark on one edge was marked on the concrete floor for consistent placement of the tape measure used for measuring deflection of the board centre. The metal tape measure was marked in mm, has a right angle metal tag at one end, and a brake that can be applied to hold the tape at any given position. All deflection measurements were made with the tape body in the same position relative to the reference mark, and the metal tag on the top surface of the board and in the same position relative to the mid-board mark.

8 concrete pavers of the same size, each of mass approx 2kg, were used as the load. They stacked easily, could be divided into 2 approx. equal mass stacks of 4 pavers, and the centre of any stack determined.

Measurements of the distance from the floor to the mid-board top were made with

a) the board “naked”

b) the plate mounted at a 68cm interaxle distance

c) the plate mounted upside down at a 50cm interaxle distance

(50cm interaxle distance cannot be achieved with the plate the correct way up due to the depth and shape of the core material)

 

In each of a,b, & c, the load was applied as

i) a single stack of 8 pavers centred over the mid-board line

ii) as 2 stacks of 4 pavers at various separations, the gap centred on the mid-board line.

Results:

Naked Board - Paver Load state               Floor to board top (mm)

No load                                                         643
8 @ 0cm (mid-board)                                 615
4+4 @ 27cm                                                616
4+4 @ 46cm                                                617
4+4 @ 64cm                                                620
4+4 @ 68cm                                                620
4+4 @ 86cm                                                623
4+4 @ 99cm                                                625
---------------------------------------------------------------------------------------------------------
BBP - IA@68cm - Paver Load state        Floor to board top (mm)

No load                                                        640
8 @ 0cm (mid-board)                                619
4+4 @ 27cm                                               619
4+4 @ 46cm                                               619
4+4 @ 64cm                                               619
4+4 @ 68cm                                               619
--------------------------------------------------------------------------------------------------------------
BBP - IA@50cm - Paver Load state     Floor to board top (mm)

No load                                                       640
8 @ 0cm (mid-board)                               616
4+4 @ 27cm                                              616
4+4 @ 46cm                                              616
4+4 @ 64cm                                              616
4+4 @ 68cm                                              616

Discussion:
With the unplated board, the measurements with the load centred, then equally divided and gradually separated shows that load position directly affects the degree to which the unplated board flexes. The greatest flex occurs when the static load is placed at the centre of the board. The degree of flex gradually decreases as the load is split and moved outward from the centre. Intuitively, if the load was equally divided and placed over the points at which the board is supported at nose and tail then no flex of the board centre would occur.
Mounting the plate on the board causes a small flex (3mm) due to the mass of the board/UPM mount system.
Subsequently loading the plate at the centre, or evenly at points equidistant from the plate centre, results in the same degree of flex. The larger interaxle distance resulted in a lesser deflection of the board centre than the smaller interaxle distance. The board flexes as if the mass of plate + pavers is equally distributed at the interaxle distance on a “naked” board.

The plate does not alter the board flex. It alters where the applied static load is placed on the board.

Edited June 2, 2020 by SunSurfer

[lowrider]

 I'm worried for your wife. SunSurfer needs a honeydew list this is getting out of hand ! Remember Red Rum Red Rum ?  Back to the garage. No one rides a bare board . Put some bindings on and re-do your experiment . 

[SunSurfer]

@lowrider The wife is happily writing her History PhD. I had a 4 day weekend because of a local holiday and time to let my mind wander, and play in the garage. Across Cook Strait, 120km away, the peak of Tapuae-o-Uenuku is glistening with the first of this winter's snow. On August 8th I head south for 3 weeks at Cardrona & Treble Cone. The Intec cables in the boots have been checked. The chosen boards have been waxed and sharpened. The legs are being conditioned with long and hilly bike rides. The wine stocks are being culled so that lots of Central Otago Pinot Noir can be sampled and brought back. And the country is 2 months since the last case of community transmitted Covid, 10 days since the last newly diagnosed case, and that is the single active case in the country.

Don't worry about me here. I'm sweet!

Worry for all our American friends at this time. (Politics proximity alarm sounds loudly)

Edited June 2, 2020 by SunSurfer

[lowrider]

Everyone seems to try to bait me with politics i'm not biting. Very happy for you and the prospects of a very nice holiday. Covid 19 abruptly ended our plans this spring for a return to the Kootenays so i look forward to some pics of your snow fields. Numbers here are up and down so prospects for some kind of plan are not looking hopeful. Beaches are being fenced off and  signs warning people away are a new reality never seen before and we don't have sharks ! I'm more a Cabernet Sauvignon person  in the chance a case showed up at the door. Play Safe !