Are washers necessary?

[Lou]

I'm building a wood and fabric plane that uses plenty of aluminum
fittings and
hinges. If I have an aluminum block on one side of a spar made of wood
and the aluminum hinge on the other, with a bolt going through, is
there
any reason for washers? It's not that I wouldn't use them, but it
helps when
ordering the correct size bolt. The plans don't mention washers but
the plans
don't call for a few items that seem to me to be necessary.
Lou

[Orval Fairbairn[_2_]]

In article
>,
Lou > wrote:

> I'm building a wood and fabric plane that uses plenty of aluminum
> fittings and
> hinges. If I have an aluminum block on one side of a spar made of wood
> and the aluminum hinge on the other, with a bolt going through, is
> there
> any reason for washers? It's not that I wouldn't use them, but it
> helps when
> ordering the correct size bolt. The plans don't mention washers but
> the plans
> don't call for a few items that seem to me to be necessary.
> Lou

Good practice in wood structures calls for a sleeve through the wood
(epoxied into place), slightly shorter than the thickness of the wood,
and large-diameter washers on each side, to distribute the compression
loads from the bolts. It doesn't mater if you have a block or a washer,
as long as there is a means of distributing the loads on the wood.

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You also want to consider future repair of the aluminum fitting. If
you use a nut inside the fabric, you will need to remove the fabric to
gain access. When practical, use nut plates inside the fabric so you
can remove the bolts from the exposed side in order to remove/repair/
replace the aluminum fitting when it becomes corroded.

Rich S.

[Lou]

> Good practice in wood structures calls for a sleeve through the wood
> (epoxied into place), slightly shorter than the thickness of the wood,
> and large-diameter washers on each side, to distribute the compression
> loads from the bolts. It doesn't mater if you have a block or a washer,
> as long as there is a means of distributing the loads on the wood.
>
> -


I looked at the plans and there is no call for the sleeve. However I
like the
idea. It sure wouldn't add weight, but I do like the idea.
Lou

[Dale Scroggins[_2_]]

"Orval Fairbairn" > wrote in message
...
> In article
> >,
> Lou > wrote:
>
>> I'm building a wood and fabric plane that uses plenty of aluminum
>> fittings and
>> hinges. If I have an aluminum block on one side of a spar made of wood
>> and the aluminum hinge on the other, with a bolt going through, is
>> there
>> any reason for washers? It's not that I wouldn't use them, but it
>> helps when
>> ordering the correct size bolt. The plans don't mention washers but
>> the plans
>> don't call for a few items that seem to me to be necessary.
>> Lou
>
> Good practice in wood structures calls for a sleeve through the wood
> (epoxied into place), slightly shorter than the thickness of the wood,
> and large-diameter washers on each side, to distribute the compression
> loads from the bolts. It doesn't mater if you have a block or a washer,
> as long as there is a means of distributing the loads on the wood.
>
> --
> Remove _'s from email address to talk to me.

I understand the original post to say that that the bolt would go through an
aluminum block, then a wood spar, then an aluminum hinge. No need for
washers to prevent wood compression.

You need a washer under the part of the fastener system that you turn during
installation. If a nut goes on the bolt and you rotate the nut to tighten
it, you need a washer under the nut. If you are installing the bolt into a
tapped hole, you need a washer under the bolt head.

If you are putting a steel bolt through these aluminum parts, use a plated
bolt and plated hardware. Otherwise your aluminum parts will corrode in
time. If the fit is close, you may be unable to remove the bolt after the
aluminum corrodes. I know you didn't ask that question, but since you
weren't sure where to put the washer....

[Orval Fairbairn[_2_]]

In article
>,
Orval Fairbairn > wrote:

> In article
> >,
> Lou > wrote:
>
> > I'm building a wood and fabric plane that uses plenty of aluminum
> > fittings and
> > hinges. If I have an aluminum block on one side of a spar made of wood
> > and the aluminum hinge on the other, with a bolt going through, is
> > there
> > any reason for washers? It's not that I wouldn't use them, but it
> > helps when
> > ordering the correct size bolt. The plans don't mention washers but
> > the plans
> > don't call for a few items that seem to me to be necessary.
> > Lou
>
> Good practice in wood structures calls for a sleeve through the wood
> (epoxied into place), slightly shorter than the thickness of the wood,
> and large-diameter washers on each side, to distribute the compression
> loads from the bolts. It doesn't mater if you have a block or a washer,
> as long as there is a means of distributing the loads on the wood.

I forgot to mention sealing the bolt, to protect it and the sleeve from
invading moisture.

Another age-old practice is to dip or brush the bolt with paralketone
(available from Aircraft Spruce, but I did not see it listed). I bought
some from them this year, so I know that they have it. It is a waxy
liquid, like Cosmoline, that evaporates some of the lighter stuff and
never really dries. It will keep moisture out of the bolt, however.

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[Lou]

On Aug 13, 11:03 pm, Orval Fairbairn >
wrote:
> In article
> >,
> Orval Fairbairn > wrote:
>
>
>
> > In article
> > >,
> > Lou > wrote:
>
> > > I'm building a wood and fabric plane that uses plenty of aluminum
> > > fittings and
> > > hinges. If I have an aluminum block on one side of a spar made of wood
> > > and the aluminum hinge on the other, with a bolt going through, is
> > > there
> > > any reason for washers? It's not that I wouldn't use them, but it
> > > helps when
> > > ordering the correct size bolt. The plans don't mention washers but
> > > the plans
> > > don't call for a few items that seem to me to be necessary.
> > > Lou
>
> > Good practice in wood structures calls for a sleeve through the wood
> > (epoxied into place), slightly shorter than the thickness of the wood,
> > and large-diameter washers on each side, to distribute the compression
> > loads from the bolts. It doesn't mater if you have a block or a washer,
> > as long as there is a means of distributing the loads on the wood.
>
> I forgot to mention sealing the bolt, to protect it and the sleeve from
> invading moisture.


I hate to show my ignorance, but it won't be the first time,
What would you seal the bolt and sleeve with?
Silicone?
Lou

[Orval Fairbairn[_2_]]

In article
>,
Lou > wrote:

> On Aug 13, 11:03 pm, Orval Fairbairn >
> wrote:
> > In article
> > >,
> > Orval Fairbairn > wrote:
> >
> >
> >
> > > In article
> > > >,
> > > Lou > wrote:
> >
> > > > I'm building a wood and fabric plane that uses plenty of aluminum
> > > > fittings and
> > > > hinges. If I have an aluminum block on one side of a spar made of wood
> > > > and the aluminum hinge on the other, with a bolt going through, is
> > > > there
> > > > any reason for washers? It's not that I wouldn't use them, but it
> > > > helps when
> > > > ordering the correct size bolt. The plans don't mention washers but
> > > > the plans
> > > > don't call for a few items that seem to me to be necessary.
> > > > Lou
> >
> > > Good practice in wood structures calls for a sleeve through the wood
> > > (epoxied into place), slightly shorter than the thickness of the wood,
> > > and large-diameter washers on each side, to distribute the compression
> > > loads from the bolts. It doesn't mater if you have a block or a washer,
> > > as long as there is a means of distributing the loads on the wood.
> >
> > I forgot to mention sealing the bolt, to protect it and the sleeve from
> > invading moisture.
>
>
> I hate to show my ignorance, but it won't be the first time,
> What would you seal the bolt and sleeve with?
> Silicone?
> Lou

No -- you seal the sleeve to the wood with epoxy (I would use T-88); the
paralketone seals the bolt. Actually, I would also use some zinc
chromate past around both ends of the bolt, too.

If no moisture gets in, the wood will not rot, nor will the bolt corrode.

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[cavelamb himself[_4_]]

Orval Fairbairn wrote:
> In article
> >,
> Lou > wrote:
>
>
>>On Aug 13, 11:03 pm, Orval Fairbairn >
>>wrote:
>>
>>>In article
>,
>>> Orval Fairbairn > wrote:
>>>
>>>
>>>
>>>
>>>>In article
>,
>>>> Lou > wrote:
>>>
>>>>>I'm building a wood and fabric plane that uses plenty of aluminum
>>>>>fittings and
>>>>>hinges. If I have an aluminum block on one side of a spar made of wood
>>>>>and the aluminum hinge on the other, with a bolt going through, is
>>>>>there
>>>>>any reason for washers? It's not that I wouldn't use them, but it
>>>>>helps when
>>>>>ordering the correct size bolt. The plans don't mention washers but
>>>>>the plans
>>>>>don't call for a few items that seem to me to be necessary.
>>>>> Lou
>>>
>>>>Good practice in wood structures calls for a sleeve through the wood
>>>>(epoxied into place), slightly shorter than the thickness of the wood,
>>>>and large-diameter washers on each side, to distribute the compression
>>>>loads from the bolts. It doesn't mater if you have a block or a washer,
>>>>as long as there is a means of distributing the loads on the wood.
>>>
>>>I forgot to mention sealing the bolt, to protect it and the sleeve from
>>>invading moisture.
>>
>>
>>I hate to show my ignorance, but it won't be the first time,
>>What would you seal the bolt and sleeve with?
>>Silicone?
>> Lou
>
>
> No -- you seal the sleeve to the wood with epoxy (I would use T-88); the
> paralketone seals the bolt. Actually, I would also use some zinc
> chromate past around both ends of the bolt, too.
>
> If no moisture gets in, the wood will not rot, nor will the bolt corrode.
>

Next question is - what to make the sleeve from.

Aluminum could possibly set up a coorosion problem.

I would suggest steel tube - cleaned and dipped in a 2 part primer like
RandoPlate or EpiBond.

Then, you are gluing to the primer (which works well) rather than the
steel surface.

--

Richard

(remove the X to email)

[Orval Fairbairn[_2_]]

In article >,
cavelamb himself > wrote:

> Orval Fairbairn wrote:
> > In article
> > >,
> > Lou > wrote:
> >
> >
> >>On Aug 13, 11:03 pm, Orval Fairbairn >
> >>wrote:
> >>
> >>>In article
> >,
> >>> Orval Fairbairn > wrote:
> >>>
> >>>
> >>>
> >>>
> >>>>In article
> >,
> >>>> Lou > wrote:
> >>>
> >>>>>I'm building a wood and fabric plane that uses plenty of aluminum
> >>>>>fittings and
> >>>>>hinges. If I have an aluminum block on one side of a spar made of wood
> >>>>>and the aluminum hinge on the other, with a bolt going through, is
> >>>>>there
> >>>>>any reason for washers? It's not that I wouldn't use them, but it
> >>>>>helps when
> >>>>>ordering the correct size bolt. The plans don't mention washers but
> >>>>>the plans
> >>>>>don't call for a few items that seem to me to be necessary.
> >>>>> Lou
> >>>
> >>>>Good practice in wood structures calls for a sleeve through the wood
> >>>>(epoxied into place), slightly shorter than the thickness of the wood,
> >>>>and large-diameter washers on each side, to distribute the compression
> >>>>loads from the bolts. It doesn't mater if you have a block or a washer,
> >>>>as long as there is a means of distributing the loads on the wood.
> >>>
> >>>I forgot to mention sealing the bolt, to protect it and the sleeve from
> >>>invading moisture.
> >>
> >>
> >>I hate to show my ignorance, but it won't be the first time,
> >>What would you seal the bolt and sleeve with?
> >>Silicone?
> >> Lou
> >
> >
> > No -- you seal the sleeve to the wood with epoxy (I would use T-88); the
> > paralketone seals the bolt. Actually, I would also use some zinc
> > chromate past around both ends of the bolt, too.
> >
> > If no moisture gets in, the wood will not rot, nor will the bolt corrode.
> >
>
> Next question is - what to make the sleeve from.
>
> Aluminum could possibly set up a coorosion problem.
>
> I would suggest steel tube - cleaned and dipped in a 2 part primer like
> RandoPlate or EpiBond.
>
> Then, you are gluing to the primer (which works well) rather than the
> steel surface.

4130 tubing, reamed to the correct ID. Try some gun blue on to and epoxy
it in place.

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