Through neglect I managed to sail with a not-too-tight internal bolt, causing only a couple threads to engage on the mast base and it separated. After disassembling, inspecting, and adjusting both of my Aeron bases I need one new internal bolt and it would be nice to have another spare in case of future stupidity.

Problem is, I can't seem to find them anywhere. They are not off the shelf bolts from what I can tell, as they are m8 with a 5mm hex that is hidden on the inside, have a chamfer like a flathead but the top is rounded. The area under the head isn't threaded, so it allows the base to rotate. At the bottom where it connects to the board nut, the m8 is hollowed out with a hex.

I can do without the hollowed out nut attachment but it would be nice to replace this bolt and not have to buy a whole new $100 base, or even have to source an unusual bolt to replace it for a similar price.

I'm guessing that other brands like Chinook or Severne use more off the shelf internals?

Buy a Chinook base and get good sleep.

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Imax1 said..
Buy a Chinook base and get good sleep.

Probably the right call...

M8 countersunk capscrew in 316 SS.

But yes, get a chinook with the one piece machined europin top and worry no more about anything ever.

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Mark _australia said..
M8 countersunk capscrew in 316 SS.

But yes, get a chinook with the one piece machined europin top and worry no more about anything ever.

Yeah I think for the price I'll try a regular countersunk and see if that works. Keep it as a spare and get a nice chinook replacement. Looks like an oval head is a little stronger but impossible to find in that size.

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aeroegnr said..
Through neglect I managed to sail with a not-too-tight internal bolt, causing only a couple threads to engage on the mast base and it separated. After disassembling, inspecting, and adjusting both of my Aeron bases I need one new internal bolt and it would be nice to have another spare in case of future stupidity.

Problem is, I can't seem to find them anywhere. They are not off the shelf bolts from what I can tell, as they are m8 with a 5mm hex that is hidden on the inside, have a chamfer like a flathead but the top is rounded. The area under the head isn't threaded, so it allows the base to rotate. At the bottom where it connects to the board nut, the m8 is hollowed out with a hex.

I can do without the hollowed out nut attachment but it would be nice to replace this bolt and not have to buy a whole new $100 base, or even have to source an unusual bolt to replace it for a similar price.

I'm guessing that other brands like Chinook or Severne use more off the shelf internals?

My question here is always the same - why was it coming undone in the first place?

People do tend to neglect their deckplate bearings and once there is play in the bearing the connections themselves start to wear and even come undone.
Many a windsurfer has blamed bad design when his deckplate unscrewed itself from the board - when in fact it was poorly-rotating bearings that were to blame. Both bearings, one either side of the U/J, need to be able to rotate freely and with no play.

So, for sure, we can replace bolts and U/Js/tendons within our deckplates but generally it's not worth it. The deckplate and U/J are key safety devices in windsurfing and no place to scrimp on money.

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Basher said..

People do tend to neglect their deckplate bearings and once there is play in the bearing the connections themselves start to wear and even come undone.
Many a windsurfer has blamed bad design when his deckplate unscrewed itself from the board - when in fact it was poorly-rotating bearings that were to blame. Both bearings, one either side of the U/J, need to be able to rotate freely and with no play.

Yes this was it. The internal flat washer was not seated well against the bottom of the UJ. In fact, it had even rounded the top part of the (not visible unless disassembled) threads because of the movement there.
Lesson learned, and at least my swim back wasn't as far as it could have been.

I must be buying the cheapo stuff cos none of mine have ever had bearings in them.

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Mark _australia said..
I must be buying the cheapo stuff cos none of mine have ever had bearings in them.

Your thinking ball bearings . I'm hoping he's thinking bearing surfaces .
Ill shut up now.

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Imax1 said..

Mark _australia said..
I must be buying the cheapo stuff cos none of mine have ever had bearings in them.

Your thinking ball bearings . I'm hoping he's thinking bearing surfaces .
Ill shut up now.

Yeah there are small plain bearing sleeves in this one, likely similar in others.

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aeroegnr said..

Imax1 said..

Mark _australia said..
I must be buying the cheapo stuff cos none of mine have ever had bearings in them.

Your thinking ball bearings . I'm hoping he's thinking bearing surfaces .
Ill shut up now.

Yeah there are small plain bearing sleeves in this one, likely similar in others.

Ive never seen that . Give us a look .

^^^ +1

I think they're talking just plastic washers n sleeves....... slippery washer/s and bush/es

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Imax1 said..

aeroegnr said..

Imax1 said..

Mark _australia said..
I must be buying the cheapo stuff cos none of mine have ever had bearings in them.

Your thinking ball bearings . I'm hoping he's thinking bearing surfaces .
Ill shut up now.

Yeah there are small plain bearing sleeves in this one, likely similar in others.

Ive never seen that . Give us a look .

You can see it in the cup on the left, lining the plastic.

Pushed out really gently. Bolt squeezes that with the flat washer in the lower piece. It had loosened up and the threads below the head have flattened out a bit. Kept it also from fully sticking out of the bottom. It looks like the brass nut took most of the stripping. A fresh brass nut spins much better until you get right under the head where the bearing spun against the threads instead of the smooth uncut region under the bolt head.

Yes, a bush..... not bearing. Thus our great interest as I've never seen a mast base with bearings

I'd say thats why they used a silly non standard both - that's rather annoying

I'm with Imax go get a Chinook and worries are over. No silly bits in there

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Mark _australia said..
Yes, a bush..... not bearing. Thus our great interest as I've never seen a mast base with bearings

I'd say thats why they used a silly non standard both - that's rather annoying

I'm with Imax go get a Chinook and worries are over. No silly bits in there

"Plain bearing" with that little piece being a bush. Yeah I imagine the seals not doing well in saltwater for a roller bearing....

This arrived. I really like the feel of it. Thicker backup ropes with larger hardware on the tendon bolts. The small size on the severne and aeron tendon bolts are really easy to accidentally strip. These look much nicer.

Pleased that you bought a new one .. put the other one in the bin and reduce risk of drowning death.

For me, a mast base is an item that needs to be replaced each year.

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JakeNN said..
Pleased that you bought a new one .. put the other one in the bin and reduce risk of drowning death.

For me, a mast base is an item that needs to be replaced each year.

Yeah the two Aeron's I've had for ~2 years? They came with a couple of my first rigs. So it was time.

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aeroegnr said..

JakeNN said..
Pleased that you bought a new one .. put the other one in the bin and reduce risk of drowning death.

For me, a mast base is an item that needs to be replaced each year.

Yeah the two Aeron's I've had for ~2 years? They came with a couple of my first rigs. So it was time.

Still using the same Streamlined mast base, probably 6 years old. Did add super thin nylon washers for between the two bolts/nuts and aluminum mast base. Original tendon too. Looks and works great.

But I did notice the loosening happening like aeroengr did, so I took the base apart and tightened and I think used blue loctite on the bolt threads, no loosening since.