Mounting Bindings--How Few turns Are Okay?

[scrapster]

Okay, I need some input about whether I'm just being too "particular" with my new equipment. I have a new metal board and I could tell right away that a few of the inserts had a thread or two (or in one case, three) drilled smooth when the topsheet was drilled out. Added to the fact that the inserts are nestled below several of the common materials found in metal boards, the inserts looked pretty "short."

So, I decided to do a board comparison test by screwing in a bolt with no bindings. I have two old glass boards and over several inserts I could go as many as four to six turns before bottoming out. With the new board, the most I could get was three and a half turns. Quite a few more gave me two and a quarter to two and a half turns. And at least one barely gave me two turns.

Normal? If not, how much of a concern is it?

I'm interested because I've already had to return one board for a similar issue. This one is better than the last, so I'm hoping just a quick clean-up with a tap may be in order and I can go happily in my way. Or, I may not even have to do anything except wait for the snow to fall next year :)

PS- Please don't mention the company name if you know it. Overall, they have been good to deal with and I'm not looking to stir up trouble.

[D.T.]

How Few turns Are Okay?

minimum of three threads engaged

[bjvircks]

An old expert I used to work for preached that design loads in bolted joints are reached with only 2 full threads engaged. I never really trusted this and always went for 3 or more.

What you have in your board at best does not leave much margin and might cause you to grind screws to length to match specific locations.

I would think a board builder would use a stop collar on his drill bit to keep the depth penetration limited. A simple removeable cover sheet would keep the collar from scuffing up the topsheet.

I'm no authority on board building, but I wouldn't like getting what you have received. I don't think it is safe.

[Donek]

I preach 3 turns. I believe that is supposed to be the ASTM standard. Boards with metal laminates typically get very thin compared to fiberglass boards. We had a number of boards with the thinnest available inserts in them this year. Properly finished, that insert will allow 3 turns, but does require extremely carefull finish work. A tap may gain you a half turn or so, but be sure to count turns on the screws when you mount your bindings.

I remember making calculations regarding this in a mechanical design class, but can't find a direct reference in my text book from that class. I did a bit of googling and found these links:

http://www.boltplanet.com/Un/un.asp?txtseries_page=UN

http://www.spiralock.com/technology/about_technology/torque.html

I also found the following quote on the practical machinist forum:

"Guys, Thanks for all the links. I had heard that 3 full threads gave full strength. I didn't realize that more than 6 threads was useless." But then this followed: "you can't trust the first two thread turns on a bolt as the threads may not be fully formed to engage properly"

Not much help, but perhaps you'll find additional help from those links.

[negedeng]

I learned as a rule of thumb:

The screw should be screwed in what the screw does have as diameter.

Means for a M6 screw

6mm diameter -> screw in for 6mm in depth

A M6 screw does hava from one flange to an other 1mm (10 threads per 10mm)

Means you would have to make 6 full turns to get a depth of 6mm.

I am not sure right now if the binding thread is a M5 or a M6. A M5 does have 0.8mmm from flange to flange .

With this you are definitely on the safe side. Maybe 3 or 4 would work as well, but as Donek already mentioned, the top of your insert and the tip of your screw is champfered. So I would not count maybe the first 1 or two threads as stong as it should be.

[scrapster]

Good points everybody. I am a bit disappointed, especially to see an otherwise beautifully crafted board undermined by a mere (but important) finishing issue--and to have it happen twice!

The manufacturer just gave me the go-ahead to try carefully tapping out the inserts without fear of voiding the warranty. I tested the inserts again this morning with a binding plate and focused specifically on the inserts I'll most likely use. If I can get another half-turn through tapping, and then order some slightly longer screws, I think I can get them each up to 3 full turns and even slightly more.

As for the chamfering issues. Well, the chamfered part of the inserts are essentially ground away. That leaves the chamfered part of the screw. From what I've read, most of the load is carried near the initial contact point between the insert and screw, so I may be okay.

Still, a few of the inserts are probably a lost cause without tapping them out to a larger size as the opening of the inserts have been widened so much. Not an ideal situation to be in with a new board.

Just ordered the correct tapping tools. Wish me luck.

[b0ardski]

What Sean quoted about the first 2 threads being fully formed should be heeded. The slight taper at the tip to ease engagement does'nt fully engage. Cutting a longer screw back at full thread will make starting the screw finicky, but allows max engagement.

When I got a new "extra glass" 173 a couple years ago, I was anxious to use it (epic powder year) and swapped the binders(old Nitro stepins) off my nidecker. I noticed the extra thickness of the topsheet only allowed the bolts off the other board 2 full turns of thread. I rode it anyway thinking "I'll get longer bolts tomorrow".

Airing off a 20ft rock into a foot of fresh the over flex of the board on landing pulled all 8 screws somersaulting me in the snow. The bindingless board went down w/out me and I post holed after it with the binders on my boots.

Luckily a skier a 100yds down at the bottom of the pitch had seen it go into a tree well or I'd have never found it.

When I tried to reattach the bindings I found the 1st 2 threads of the screws were too striped to engage even the unused inserts. I walked out until an employee gave me a snowmobile ride back to the village.

Highly embarrassed I bought longer screws at the shop and had enough thread left in the partially stripped inserts to engage 3 turns before bottoming out and haven't had an issue since.

Turned out to be a good story but could've been much worse.

[Donek]

You may have another option. If the board has a machine gun or 4X2 hole pattern you could use more than 4 screws (depending on your bindings) and dramatically increase the retention strength of the setup.

[Petrol]

The manufacturer just gave me the go-ahead to try carefully tapping out the inserts without fear of voiding the warranty....

I'd give the manufacturer the go-ahead to accept a return shippment on his FedEx account and to try carfully building a replacement board with useful inserts without fear of an immediate & full refund...

[Aracan]

I'd give the manufacturer the go-ahead to accept a return shippment on his FedEx account and to try carfully building a replacement board with useful inserts without fear of an immediate & full refund...

+1 on that.

I mean, grassroots movement and all that is a fine thing. But the way you tell the story, it sounds like you paid for a brand new metal board, which is not safe to use. And the manufacturer says it's okay for you to try and render it usable? On your own time, with tools you had to buy for the job?

Call me bitchy, but should I ever be in the happy situation to order a new board (which I hope will come) ... well, you can finish that sentence for yourself, I guess.

[scrapster]

I hear you both, Petrol and Aracan. Honestly, I'm just tired out by the whole experience right now. Two boards shipped, both disappointing. Countless emails and photos. Nearly a month of waiting for FedEx ground. One board temporarily lost by FedEx Ground. Some shipping costs incurred by me. Over an hour of driving to pick up the second board.

Much of this was the fault of the shipping company, but still, cumulatively it saps the energy out of you. Not to mention I now have my wife saying, "Are you messing with that damn board again?!" And she has a point.

But your words are encouraging and may serve to build my "fight" back. Thanks.

BTW, I've attached pic of the worst insert. The ones next to it (to the right) are indicative of how most of the inserts look.

[Petrol]

"eye of the tiger" and all that rot aside, I really do encourage you to stand firm on your expectations to recieve the dream board you ordered and paid for. Which I'm sure that you paid plenty for beings as its a new metal board.

Having just returned from a "lunch-break" where-in I drove like the wind to meet my granite sub for the third time to insure that he correctly addresses the remaining issues with his work, I understand the difficulties and the hassle because it would have been much easier for me to sluff it off, but I know that it would fester and bug the chit out of me Every Time I see it.

This and it will help Him and all following customers as my demands of quality will Raise the level of his game thus benifiting everyone

[Buell]

+ another on making them get it right.

You paid full price for the board and deserve a first quality snowboard. It is summer anyway (for most) so there is plenty of time to get the board you paid for before the season starts.

Even if you can get it safe to ride, what happens when you want to sell it and have to explain about the inserts. Down goes the resale value. The builder either needs to compensate you for the lower resale value or get you a first quality board. They can pay shipping this time.

Otherwise, return this one and just get a board from a different manufacturer who can build a good one.

[bjvircks]

Petrol... you are having someone build you a submarine from granite? How's that working out? (ok, stupid comments aside... I hope the counters, shower, whatever turn out as you want)

Scrapster... I agree with the others. I don't think it is right for it to be on you to fix the builder's screwup. You in all likelyhood will end up with a quirky setup which might require you to memorize which screws went into which location and you will take a long time to actually trust your attachment to the board. I think you should get a replacement board (built correctly!!) and considerable financial 'consideration' from the builder.

[BlueB]

Mark,

Maybe it's fair to mention that you bought a discounted board?

It is still BS that they've sent the first board without describing (or inspecting) the condition properly. Even bigger BS that they've built the replacement board and repeated the mistake... :(

You should probably demand a full refund, including the shipping and just build with someone else. That should teach them.

[scrapster]

BlueB-

A fair point. But the discount was only because the board was "off the rack," so I didn't have a choice in the graphics. It was still sold as "new and pristine." I also have paid to ship it (one way) twice now.

That's what makes the whole thing so strange. They said OK when I suggested they give me a different topsheet on the new board--which was cool of them to do as compensation for some of my hassle. But to still have the original problem is just wacky and makes no sense to me at all (both in terms of being a craftsperson and in running a business.)

[scrapster]

Two other points come to mind:

1. When all is said and done, the discount only amounted to about $75 off the price of a new custom, which isn't much considering we're still talking about a board that cost me nearly $1,000.

2. If the current board is fixable and considered a warranty issue (ie, I'd be getting the same board back, repaired)--maybe it does make sense for me to just try and fix it here first and avoid the hell that is FedEx Ground.

See, this is the kind of all consuming stuff that is driving me nuts! I should be working right now.

[carvedog]

I've got an idea.

Send it to me. I will make sure to ride the insert in question.

I am not light. Ok, I'm kind of fat. But I ride real hard.

If I can't get it give way in a week or two, I'll send it back and you can ride with conifedence.

[scrapster]

Nice!!! ;) I needed a little levity.

[jacopodotti]

Hi

I think that you have to screw as deep is the thikness of the corresponding bolt.

I don't know the thikness of a M6 bolt , if you have problems in checking it I can have a look at my hardware shop( I'm in Italy so everything is in cm/mm and not in inches).

[Fleaman]

I am not sure about other people, but the stock screws that have come with my bindings were never long enough to mount on any of my boards. I have a board with the same dead space between the threads and topsheet but there is still plenty of good thread deeper in the insert hole and just bought some long M6 screws. I used my calipers with a depth gauge and measured to the bottom of the hole with the bindings on. I then cut the screws with a dremel cut off wheel a touch shorter than the depth and filed the ends of the screws down to ease engagement. It is a bit more work but I think it is necessary considering the varying thicknesses of different boards. I always ensure I get at least 3 full turns on the screw and with this method, I have never had a problem.

Judging by your photo, IMHO the screws you have are too short.

I just reread your OP, I did not realize that your turns on a bare board are really low to start with. sorry

[scrapster]

Well, heard from the manufacturer again. The final word--they are confident that the inserts will be fine as is--a one line reply after a long email from me seeking advice on the right thing to do. I guess that settles it.

I made the company aware that I no longer intend to re-tap the inserts. I do not wish to incur any liability on my part for changes to the board. I'll ride it as-is from the factory, with the correct size screws and hope for the best. They have my concerns on record.

Thanks for everyone's advice. I wish I had taken some of it a few months earlier.

[Corey]

+1 more voting to send it back. Ideally at their expense, and before you touch it with a bottoming tap. Think of it this way: You're not inconveniencing them, they're inconveniencing you with this hassle. It's not reasonable to have that few threads in a brand new board unless it came with a correspondingly healthy discounted price.

If I were the maker of that board I'd jump at the first opportunity to fix the issue, especially given the small niche market that is alpine. Then I'd hang my head in shame after you got a second defective board and give you something extra for your trouble (stickers, hoodie, whatever) along with the third board. Who knows, maybe you've helped them discover a fundamental error in their assembly process that they've missed in their QA checking? Better to discover this now than before they've made a big run of 2011 boards!

I went through a similar thing with some fancy shocks for my car (~4x the cost of a nice metal board). It took much more work than I expected to get things fixed, but they did fix things reluctantly after MANY emails and phone calls. Their poor customer service will cost them much more via my warning other racers away from their store than just fixing the issues in the first place would have cost.

[scrapster]

Judging by your photo, IMHO the screws you have are too short.

PS- The screw in the photo is not a mounting screw. Its just there to help the camera focus on something.

[kieran]

i guess having seen that snippet of topsheet graphic, everyone knows who the manufacturer is now.