Chronicles of a home made plate MK II

[SunSurfer]

Approx 1.5 kg for combined weight for

- plate

- front & rear hinge slide hardware

- all mounting screws/bolts/nuts.

Mounts to Apex type pattern (roughly a 13 x 3 cm rectangle).

Required extra inserts into my oldest carving board.

Stronger / smoother slide than Mk I.

Based around four, modified, 316 stainless steel 6mm wire rope clamps as available from ships chandlers & rigging companies.

Having recently read many of the posts on gear failure on this board I'm pretty happy this will be up to the task.

This is what I was thinking about when I was wishing for a computer controlled router. Managed without it.

SunSurfer

PS: Not quite enough snow here yet, but not long to wait.

[lowrider]

Keep it simple stupid. Great !!!! Now you have single handedly created a global shortage of old decks for home tinkering.:lol:

[SunSurfer]

Pisst Plate have given us the low down on theirs. http://www.bomberonline.com/vbulletin/showpost.php?p=308840&postcount=11

Donek - Sean Martin has kind of shown his in the video.

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Bomber plate mechanism is still under a carbon "shroud".

How else can you do this?

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The photos below show the hinge/slide mechanism from my Mk 2 front unit.

The UHMWPE block has a 5mm deep, "dumbbell" shape, routered, cutout to accommodate the 5mm stainless steel axle, and the base units against which the U bolts are secured as they rotate with the axle. The axle part of the cutout is 10mm wide to allow for 5mm fore/aft movement.

There is a slot cut all the way through the plastic block, and at right angles to the axle axis, to take the U bolts. In the front unit this slot ensures the axle slides evenly forward and back.

In both front and rear units these slots, combined with the Nyloc nuts at either end of the axle, also help transfer lateral forces from plate to board.

The U bolts are threaded @ M6x1 and on the "U" part are 5mm thick.

There is a P-Tex sheet above and below the green plastic block. The metal plate above the block is currently 3mm aluminium, but could be made thinner by using stainless steel.

The axle and U bolts do not move in relation to each other. All moving parts are stainless steel on UHMWPE/P-Tex. Stainless steel moving on steel is prone to wear unless well lubricated.

The axle is solidly supported underneath along it's whole length apart from at the fore/aft slots.

The snowboard has had new inserts placed in the 12.9 x 3cm pattern of the UPM, but one side of the UPM rectangle has been aligned with the 4x4 pattern on the board for both front and rear units. The resulting distance between the outermost front and rear new inserts is 62cm, which is NOT consistent with the UPM pattern.

At the time I put the new inserts in I knew the 12.9 x 3cm dimensions but not the fore/aft dimensions of the UPM.

SunSurfer

[SunSurfer]

New insert pattern and rear unit shown below. Here the 5mm deep axle slot is also only 5mm wide. The front unit slot is 10mm wide. It could be made wider within the limits of the UHMWPE block but it is not necessary to have more than 5mm fore/aft slide movement.

SunSurfer

[Donek]

That's nice and simple. I'd be a bit scared of the 5mm shaft. I considered using a 5/16in (8mm), but opted for a 3/8in (9.5mm)

The simple elegant use of readily available hardware is cool. I'm curious how you got a flat head screw going into the u-bolt though? For a production model, I'd be a bit concerned about the retention strength at those points. The fasteners are very close together and the flat head has very little to support it. I think your wood core is likely to be crushed and things will loosen up. I'll be laminating aluminum plates into the plate to enable top down flat head hardware mounting with the 4X4 version.

[lowrider]

Most of the load on the plate will be compression not a lot in tension unless you ride hard on the tail like our knuckle dragging counter parts AKA soft booters.As far as riding what you have made no issues it will work fine! The top sheet and sub layer of glass will support the screw heads. Been There Done That! How is the snow pack down under ????

[SunSurfer]

I'm curious how you got a flat head screw going into the u-bolt though?

http://www.anzor.co.nz/?T=173

Countersunk head barrel nut courtesy of my local stainless steel fittings supplier site. The top of the rideable plate has had another layer of sheathing cloth and epoxy applied which went on after the countersink holes were drilled.

I figure the major load on the axle is compression as the G level rises in the turn. There the axle is squeezed between the plastic and the the grooved stainless clamp base.

The groove in the clamp base has been filed so that force is applied across the whole width of the base. As supplied, the groove is slightly lower in the middle compared with either end. If you tighten up the U-bolt too tight you can bend the axle unless you make this mod.

Front axle moves in its' slot in the event of a sudden decelleration, while the rear axle is compressed along the whole rear side of its' slot. The slots have been cut so that the axle is supported on all sides as much as possible. I could have used a semicircular tipped router bit instead of a square for the rear slot, but I'm not sure that that is actually necessary.

All that being said, the design principles could be fairly easily upsized by use of -

a thicker UHMWPE plastic block (current is 1cm)

a thicker axle

a different size clamp, and there are a wide range of sizes available.

stainless steel plate on the top of the plastic block to reduce the overall height of the base block.

As the title says, this thread is a "chronicle", and I continue to make adjustments and changes to the design, so that what you see here is a step or two behind the current state.

I get to actually ride this in early August. Although the snow is falling here and the ski season has begun, my day job prevents me getting up there just yet.

I have the rideable version mounted on my oldest carving board in my garage, and I am itching to get up there and try it!!

Just as before, I have no commercial interest in this design process.

This is an Open Source design and others are welcome to use it as they wish, and at their own risk.

I understand that Donek & Bomber are commercial entities, and that Sean and Fin make their living out of what they design, build, and most importantly sell.

There are also other people participating on the board who are working in this area, and making plate product for sale on a smaller scale.

SunSurfer

[Donek]

Most of the load on the plate will be compression not a lot in tension unless you ride hard on the tail like our knuckle dragging counter parts AKA soft booters.As far as riding what you have made no issues it will work fine! The top sheet and sub layer of glass will support the screw heads. Been There Done That! How is the snow pack down under ????

In order to apply a moment (twisting force) to the board that puts it on edge, you have compressive forces on one side of the board and tension forces on the other. This is how binding inserts get pulled out of boards. An average rider is capable of applying close to 900lbs of tension on a single insert. Based on the photos I see, he can expect at least 400lbs of tension on those screws. Depending on the core material, that could become an issue.

A standard insert has a cross sectional base area of .33 square in. 900lbs represents a compressive stress of 2.7ksi.

I'm not sure of the dimension of the flat head in his situation, but a standard m6 flat head has a cross sectional area of .128 square inches. 400lbs of force represents a compressive stress of 3.1ksi (exceding the above). This calculation does not consider the wedge shape of the flat head which is likely to split the core. Unless these screw heads are dramatically different from what I have described, there is a significant danger of pulling the screws through the plates core. Given the fact that a rider will find he is going dramatically faster on an effective plate system than without. This design represents a significant hazard to the rider.

[SunSurfer]

Thanks for that Sean.

I had wondered about how the plate would cope with the loads on the mounting bolts. I had been considering metal inserts in the plate to spread the loads at those points.

You have made a very cogent case for reinforcement and load spreading.

SunSurfer

[SunSurfer]

Information on the strength of the various SS fasteners / axle rod etc can be found here.

http://www.anzor.co.nz/?T=30

a kilo Newton (kN) is approx. a 100kg (225lb) load.

SunSurfer

[SunSurfer]

8mm axle version now in progress. With a tiniest amount of shaving of the inside of the U-bolts on the 6mm rope clamps an 8mm axle fits snugly. M8 stainless bolts available locally in lengths up to 220mm, with smooth shafts for all but the last 40mm.

SunSurfer

[SunSurfer]

Back from 3 days of riding on a mix of snow / ice and boards. Both 5mm axle and 8mm axle units were used with no problems.

The plate used with the 8mm axle unit was made from an old, scarred Hot Logical carving board and is fairly stiff when tested by bouncing on it as per the video by Sean Martin. The aluminium insert inlaid into the plate has been both epoxyed and bolted to the plate. The epoxy must be applied within a minute or two of freshly sanding/abraiding the aluminium surface. The aluminium rapidly oxidises.

Total weight of 8mm axle units and the plate is 1850 gram. (approx. 4lb 3oz)

The photos show the plate and hinge units after their first full day of use on hard packed black and blue runs that are narrow and crowded.

And yes, Lowrider, I was wearing an enormous smile!

First tries on a plate were back on the absolute beginners slope as I checked out that I hadn't made some major miscalculation and the whole thing wouldn't fall apart on the first ride. The feel is quite squishy and odd at low speed but no problem sideslipping/ hockey stopping even from the first run.

In the afternoon cut up crud/bumps it was like getting 18yr old knees/quads/reflexes riding the 5mm axle/plate combo (which is significantly softer, made from a non carving snowboard) on a 167cm Avalanche board made in 1997. Before trying it I'd been riding a recently acquired second hand fibreglass Coiler AM 177, 21cm waist, (no plate - I haven't had the courage to cut into its' base!) in the same snow. Plate equipped board was much better in this setting.

The 8mm axle plate was on my 180cm Riot Supercarve which got tried two days later. In between we'd had a day of rain and then freeze so the snow was now hard packed / icy over most of the upper mountain and slush on the narrow access trails back to the skifield base. By Colorado standards our runs are very narrow and crowded so a lot of turns get made!! Riding faster, and more sure footedly in those conditions than ever before, and again my 50+ yr old knees really didn't feel the strain I would normally have expected.

Heading to the South Island in 12 days time for just over a week of snow time in and around Queenstown/Wanaka while the FIS Junior World's are on.

Some minor tweaks will be made between now and then.

SunSurfer

[vapor]

I've noticed that you placed the front axle in front of the binding placement.

Wondering how you came up with that location as I have a similar setup and noticed the same suspension feeling you describe.

Did you design that in mind and do you think having the axle more under the center of the binding will limit the cushioning effect.

[SunSurfer]

Took my cues from photos of the Apex Composites plate as used by the Canadian team. In addition B Karl plate axles are also set outside the binding plate centres.

Haven't tried axle under binding plate centre, but would anticipate less shock absorption in this position.

SunSurfer

[SunSurfer]

Been riding every day for the last 6 days, have a glass Coiler AM 177 and the 8mm axle plate equipped Riot Supercarve 180 as ride choices.

Days start out on groomed cord, and then as expected the snow gets cut up and lumpy.

My own carving is making progress, and have had the pleasure today of riding with a New Zealand carver, and a visiting US snowboard/ski instructor from Lake Tahoe, Dick Schulze, who is listed amongst the California hard boot instructors on the Bomber list.

Today have ridden non stop between 0845 and 1600hrs with a 10 minute lunch break. Having ridden both boards on fresh groom and later in the day conditions over the last 6 days, my choice is firmly for the plate equipped Riot. I have been carving all day, and the thing that strikes me as being most different from my previous days on the snow has been the lack of fatigue in my quads. Bear in mind these are 51yr old quads that get a moderate amount of road & MTB cycling to keep them in shape. By smoothing out the bumps I carve better, and with less effort. I don't notice the extra weight of the plate on the chairlifts. I am riding faster than I have ever dared before and feel more in control of my board.

I think there will be a small group of carvers who will not benefit from a plate. They only ride perfectly groomed cord at under 20 km/hr!

SunSurfer

[lowrider]

Has anyone else been brave enough to try your setup?? Thanks for your posts it's bringing back my memories of riding plates the first time. Get to work on some plates and vary the flex,opens up a whole new world of riding. Good Luck!

[SunSurfer]

I have discarded the 5mm axle model. There was some minor deformation of the axle after a couple of days riding.

Having completed my holiday in the South Island, and having just seen Sean Martin's videos on destruction testing and his production version (Vendors Section), I disassembled my 8mm axle plate mechanism.

8mm axles remained true and round.

The fixed axle plastic block groove and locking plate showed no significant wear.

The sliding axle UHMWPE surfaces showed significant wear. In particular, the surface on the side nearest the plate had visibly lost some of it's thickness, with this most pronounced at the most lateral parts.

Sean's design has a plastic block around the sliding axle. By this means he spreads the loads on the sliding axle in a way that I am unable to achieve accurately in my garage workshop. His design is less likely to have such a significant wear problem.

My hinge/slide design works, but has wear limitations that will require regular checking and replacement of some of the bearing surfaces.

SunSurfer

[nigelc]

when are you next at ruapehu sunsurfer? i would love to check the plate out

[SunSurfer]

Hi Nigel,

Unfortunately for a range of reasons (not injury) I won't be getting any more snow time this winter. Boards have been storage waxed and put away. Starting to think about how I might try and produce a similar UHMWPE block around the sliding axle as in Sean Martin's design for next season.

If you are interested I could e-mail or post some more photos of the version that was ridden in the South island.

Been riding with another carver this year at Turoa, and by chance caught up with them at Cardrona. Sorry to have missed you.

SunSurfer

[nigelc]

we were in queenstown twice this year - before and after your trip down there unfortunately. I will be riding as much as possible at ruapehu for the remainder of the season.

Its a shame I wont see your plate. i have been following the progress avidly and having seen you ride last season it would be easy to see how the plate has made things easier for you.

never mind.......next season...

[SunSurfer]

I've had about 10 days on the plate equipped Riot.

For the trip I made to the South Island I made new caps for the slide slot. These were made from layers of 3mm aluminium and a layer of snowboard base P-Tex. The aluminium was freshly abraded immediately before application of the epoxy. The P-Tex was abraded and flame treated immediately prior to epoxy application and clamping.

These photos are lit to try and show the extent of the wear on the UHMWPE and P-Tex bearing surfaces of the slide unit I rode for about 7 full days riding in the South Island. One cap unit shows more wear than the other, I don't know why, and the wear is most extreme at the lateral (outer) side of that cap. This was my heelside, the left side of the board, and the side of the green base unit nearest the lens.

The P-Tex shows more wear than does the base unit's abrasion resistant UHMWPE (even UHMWPE comes in different versions and colours).

For those of you with eagle eyes, yes, the slide was the rear unit on my plate.

Although this is not the way most pundits would have you mount a plate, I deliberately chose this way after observing the way the snowboard responded to sudden shock loads in a bench test setup. Essentially, the whole board moves/vibrates with the shock independent of whether the slide unit is mounted at the front or rear.

I decided I would rather have the most solid (hinge only) mount under my front foot. Only time will tell whether it makes any difference to performance to have the slide unit front or rear. From the photos of the Canadian Olympic team boards it seems the jury is still out on this one.

SunSurfer