Daydreamer update

mike and Judy · Guru

Daydreamer update

dave06 · Guru

well theres a lot to be answered in amongst that lot. the ammount of flex cannot be "measured" but it must be allowed for, even a bus going over a "speedhump" on a little bit of an angle produces enormous twists, stand back somewhere and just watch one

when attaching the seperate carcases together (assuming the carcase consruction method) then drill the attaching screw holes a little larger than would normally be necesary and use large head screws or place a washer on the head of the screw

this allows the screw to move between one carcase and not try to "breakout", the same applys when attaching the carcases to the benchtop, enlarge the carcase side of the screw hole and place a washer over the top of the screw

for every 1.5 - 2.0 mtrs of bench space at least 2 mm expansion/motion gap would need to be placed or the whole lot will "pop" off, these can be covered by cupboards or sinks or microwaves

if you use mdf, and there is no reason why you cant, use "moisture resistant mdf" this can be purchased as benchtops or melamime coated or just plain sheets, much easier than carcase construction, they are then not affected by moisture intrusion

ply wood is an excellent choice for all your cabinetry, possibly better than mdf and faster than carcase construction, but just be aware that if you use standard ply in "wet" areas it will be subject to "blowout" all the sections of ply will come apart, even if you coat the exposed surface with paint or stain, this can be overcome by using "marine" grade plywood

but just try to "think ahead" a bit and give the cabinetry a little bit of room to "move" particularly over longer sections

larger attaching holes with either large head screws or a washer, give them room to breathe

but all in all it looks to be going swimmingly so far

ibbo · Guru

Mike,not much I can add to Daves comments.One little tip that may be of interest to you regarding rivets.One of the things the Navy aircraft fitters used was that on some stress panels the rivet head was coated with Araldite.This plus the rivet made sure that nothing moved when the jet was shaken during flying and cannon firing.Will you be using Hispano 20mm cannons?..........just jesting.Cheers.Ibbo wink

Palebushman · Senior Member

While we were up in Sapphire enjoying Mike and Judy's hospitality, Mike showed us around his pride and joy, and I must say that he is doing a brilliant job of it so far.
Taking on the task of converting a huge bus like Karen, into what will be a beautiful mobile home, is certainly a feat that has all my admiration. Mike has all the skills and equipment to do the job, and from what we saw, 'Daydreamer' will be awesome.

mike and Judy · Guru

Ha Ha Ha Ibbo, Will be using a Gatling gun ,roof mounted to blast all the bridges in the cities,(if I get there) before I go under em and lose my windscreen,
Interesting comment on the araldite, they aint moving now, how much can I expect em to move under pressure from city traffic

dave06 · Guru

it's not so much the extreme movement but a series of small movements over a lengthy time "metal fatigue", something I forgot to warn you about, sorry about that

there is also the question of "earthing" your body to the chassis with a good quality "earth strap" preferably brass or heavy copper, you must also ensure the engine earth is also earthed to the chassis thereby creating a "constant" earth from alternator to all metalwork

the reason for this is that if you use differing metals, aluminum pop rivets into steel sheeting, then you will get electrolysis around the rivet contacts, this will cause the surrounding metals to corrode very fast and then the rivets will "pop out" not a very desirable outcome, another substitute for the araldite is silicon sealant squeezed into the hole before you insert the pop rivet this will slow down the movement and hopefully reduce the fatigue

twobob · Guru

aluminium work hardens, more rapidly than steel. I think that why the aircraft industry use aridite, to spread the work to the ajoining panels.

Mike I think if you want this thing to last forever, then that takes money, time and travelling experience. Just do as you are doing, leave room to move. Only as you travel, will you know if that was enough room. I would not go over the top on this.

Yep buses flex, but more so Caravans, as the chassis are different. If it works in a van, you should be right.

Basil Faulty · Guru

dave06 wrote:

it's not so much the extreme movement but a series of small movements over a lengthy time "metal fatigue", something I forgot to warn you about, sorry about that

there is also the question of "earthing" your body to the chassis with a good quality "earth strap" preferably brass or heavy copper, you must also ensure the engine earth is also earthed to the chassis thereby creating a "constant" earth from alternator to all metalwork

the reason for this is that if you use differing metals, aluminum pop rivets into steel sheeting, then you will get electrolysis around the rivet contacts, this will cause the surrounding metals to corrode very fast and then the rivets will "pop out" not a very desirable outcome, another substitute for the araldite is silicon sealant squeezed into the hole before you insert the pop rivet this will slow down the movement and hopefully reduce the fatigue

Thanks Dave - I was going to waffel on about electrolysis.....
Regarding the poprivets, the trick is to use sikaflex as an adhesive with poprivets to hold the parts in place untill the Sikaflex cures or you could use skin clips and then fill the holes after....
Sika is great stuff it holds aluminium bodies on everything together even ships....
Have a squiz here; http://www.sika.com.au/cmi/auto_applications.htm

It is far superoir to silicone but it costs more.

dave06 · Guru

the flexing motion in a bus is far more pronounced than a caravan, simply by the placement of the wheels, caravan wheels are centred and bus/motorhome wheels are at each corner, motorhome builders get away with it by placing the cabinets in the centre and keeping them short

the longitudinal flexing is far more damaging to long cabinets than the inadvertant spasmodic flexing of a caravan, I know because I have had both, and having built a few motorhomes (my own and others) I know the pitfalls, they are many and varied and a lot are yet to be encountered by Mike ( water tank, grey and black placement) but they must be dealt with as they arise

I agree sikaflex is far superior than silicon sealant and I would choose that but the cost comparison may be overboard, and may actually work against the setup in that it will not allow for movement and thereby create seams of weakness, better to let it flex a bit than to have it buckle

mike and Judy · Guru

Thanks for the info gentlemen, however its a bit late as I have used silicone and oversize holes on the rivets, andt he cabinents will be held together with metal threads and a hard silicone rubber washer, and a maximum lenght of 2 metres I think will be sufficient
Thanks again

dave06 · Guru

onward and upward Mike, onward and upward!!!