Author Topic: Bolts for Dolts - materials, sizes, sourcing  (Read 1973 times)

StellaBlu

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Bolts for Dolts - materials, sizes, sourcing
« on: September 02, 2022, 01:15:18 PM »
The definitive bolt thread!

Can someone please inform me of the best material for foil bolts, in terms of strength, corrosion resistance, etcÖ?  Titanium vs Stainless?  Assume Torx is recommended for M6s, and normal hex for M8?  Anything else to look out for?

What about T nuts?  Im mostly used to brass, but if other materials are better I would like to know.

Iíve been getting most of my hardware from ProBolt, which has a decent selection, but if there are other sources that are recommended, please let me know.

Thanks!

jondrums

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Re: Bolts for Dolts - materials, sizes, sourcing
« Reply #1 on: September 02, 2022, 04:15:49 PM »
McMaster Carr all the way for me - they have every fastener you could ever want in stock and they ship fast.

I use torx on M6 flatheads (T30) and Allen on M8 Flatheads (5mm).  Torx would work will on M8 as well (T45) but I'm too lazy to carry around the tool.

I have found that tail mounting bolts work perfectly fine with Stainless 18-8 material, which is low cost and corrosion resistant.  I still use tefgel to make sure nothing seizes up because saltwater is a bitch.

If you luck out and have a really really good hardware store nearby (in the US) that stocks metric stainless flathead machine screws, they will almost certainly be 18-8.  Good luck finding the fasteners you need in a hardware store - very rare in my experience.

For the fuse-to-mast fasteners, 18-8 has been perfectly fine in the M8 size.  But when I was on Takuma with the M6 bolts, I broke enough bolts that I switched to Stainless A286.  These are still pretty good for corrosion, but strength is almost double of 18-8 (130KSI vs 70KSI).  Keep in mind that they cost about 25x more than 18-8 - like $10/bolt!  You could also try Stainless 316 which is only a little cheaper and a little less strong versus A286 (100KSI vs 130KSI ultimate strength).

I have also never had a problem with Fuse to board fasteners in M8 18-8 material.  I used to use M6 in 18-8 and don't recall an issue but why mess around with M6 on this joint? - really no benefit going smaller there.

If you're using M8 in the mast tracks, I don't think it matters whether you use brass for the T-nut or not.  Should be plenty strong.  I have a set of nice thin stainless t-nut inserts but I don't know the exact stainless material (likely 304 which is similar to 18-8).

StellaBlu

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Re: Bolts for Dolts - materials, sizes, sourcing
« Reply #2 on: September 02, 2022, 05:02:00 PM »
This is super helpful and exactly what I was looking for.   Thank you.  Iíve got my work cutout googling the differences between 18-8, A286 and 316.

exiled

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Re: Bolts for Dolts - materials, sizes, sourcing
« Reply #3 on: September 02, 2022, 05:18:12 PM »
Anyone have a source for the long M8 bolts that Axis uses for their mast to fuse connection?

StellaBlu

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Re: Bolts for Dolts - materials, sizes, sourcing
« Reply #4 on: September 02, 2022, 07:06:54 PM »
Iím digging in deep on McMaster now - should I be looking at the 90 degree bevel m6 or 82 degree. The world shouldnít be this complicated.

finbox

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Re: Bolts for Dolts - materials, sizes, sourcing
« Reply #5 on: September 02, 2022, 07:59:59 PM »
boltdepot.com for the long axis bolts- they are good that you can order what you need. McMastere has fixed sized packages only

jondrums

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Re: Bolts for Dolts - materials, sizes, sourcing
« Reply #6 on: September 02, 2022, 09:35:29 PM »
for sure the 90deg flatheads

Here is the correct screws for the axis carbon mast M8x30 flathead.  pick torx or hex key
https://www.mcmaster.com/flat-head-screws/system-of-measurement~metric/thread-size~m8/length~30mm/material~stainless-steel/drive-style~hex/drive-style~torx/
« Last Edit: September 02, 2022, 09:40:18 PM by jondrums »

jondrums

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Re: Bolts for Dolts - materials, sizes, sourcing
« Reply #7 on: September 02, 2022, 09:37:49 PM »
also here:
https://axisfoils.com/products/stainless-steel-screw-set

$44 sounds steep, but they are 316 stainless and you get the two stainless torx L-wrenches, which are surprisingly hard to find

gyre

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Re: Bolts for Dolts - materials, sizes, sourcing
« Reply #8 on: September 03, 2022, 10:22:51 AM »
I always get extra bolts from Accu.co.uk.  They have a good selection of metric 316 (aka A4) Torx screws and they sell them individually.  Stock varies over time so there's a longer lead time if they have to make a new batch.  Shipping to California tends to be about $8 is as surprisingly fast.

For the M8 countersunk torx, they can be T40 or T45 depending on whether they're ISO or DIN standard.  Head size can vary too but probably not enough to make a difference on most setups.

Link to 316 M8 Countersunk Torx screws:
https://www.accu.co.uk/32-hexalobular-countersunk-screws?Material=Marine+Stainless+Steel+%28A4%29&Thread+Size=M8+%288mm%29&page=1

PonoBill

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Re: Bolts for Dolts - materials, sizes, sourcing
« Reply #9 on: September 03, 2022, 02:20:57 PM »
In my experience, the biggest issue with bolts is wearing out or stripping out the head. For this reason, I use strictly Torx bolts which wear better than Allen, and far better than Phillips. The second biggest issue is seizing, which is minimized with TefGel. The strength of the bolts is a minor issue since I don't really torque these bolts to any degree that would break them (though I use an impact driver, but I don't get carried away with it). The Axis equipment doesn't put any bolts in shear other than the stabilizer.

I use a lot of metric fasteners in my shop, so I buy bolts in bulk. I find "cheap Chinese" bolts to be more than good enough for most applications. You have to dig deep into Alibaba to find the best stuff in quantity, but Aliexpress has several vendors selling 316 stainless (they say) countersunk Torx screws in 6 and 8mm up to 70mm long in quantity 50 for about the same price as McMaster-Carr charges for 3 or 4. If I was worried about the strength I'd use specialty bolts like ARP. Most of the online fastener companies are reselling stuff made elsewhere--and I wouldn't be surprised to find that "elsewhere" means china. I find I can get longer screws by contacting the vendors. The overall quality is good, I've used a lot of them replacing screws in my KTM 390. The stock Allen screws on this made-in-India bike strip out the heads if you look at them hard.

I like Accu's fasteners, especially the blackened stainless but they are at least ten times the price I pay for 316 Chinese bolts.


« Last Edit: September 03, 2022, 02:41:45 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

AndrewTauSh

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« Reply #10 on: December 04, 2022, 12:11:15 AM »

 


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