My life with Python trikes Mk1 , Mk1.5 , Mk2 ?

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I have been researching PMF ie. Poor Mans Fiberglass
It appeals for a number of reasons:-
a) cheaper than the real thing
b) less toxic materials
c) less smelly
d) less temperature dependent [ could even harden in the house ]
e) we all have ' see through ' sheets & lot's old paint ! so could be free ?

There seems to be 2 methods advocated Titebond wood glue or paint.
I am considering trying polyurethane varnish as an adhesive for the cotton ? then paint to get colour and waterproofing further ?
The 2 mudguards will be simple to build [ only 4 pieces each ] so will be ideal to experiment on ?

Maybe as the cardboard was very good quality double fluted it could be a good base and forget the plywood altogether ?

Paul
 
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I have been researching PMF ie. Poor Mans Fiberglass
It appeals for a number of reasons:-
a) cheaper than the real thing
b) less toxic materials
c) less smelly
d) less temperature dependent [ could even harden in the house ]
e) we all have ' see through ' sheets & lot's old paint ! so could be free ?

There seems to be 2 methods advocated Titebond wood glue or paint.
I am considering trying polyurethane varnish as an adhesive for the cotton ? then paint to get colour and waterproofing further ?
The 2 mudguards will be simple to build [ only 4 pieces each ] so will be ideal to experiment on ?

Maybe as the cardboard was very good quality double fluted it could be a good base and forget the plywood altogether ?

Paul
Nothing to lose except time & materials. It would certainly be very lightweight.
Would you reinforce all joins with extra "strips" of fabric inside/outside?
Plasterers fibreglass jointing tape might be good for that (maybe).
 
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Nothing to lose except time & materials. It would certainly be very lightweight.
Yes it feels light will weigh it when a bit further along.

Would you reinforce all joins with extra "strips" of fabric inside/outside?
The inside view shows small right angled pieces holding the sides to the base and front , I would add more to make them full length of the joint for strength [ currently where there are none there is a fillet of hot glue ]
Inside I am leaning towards just a couple of thinned coats of varnish , that way I can see through it to watch for water ingress ?

Plasterers fibreglass jointing tape might be good for that (maybe).
No I think it best to stick [ pun ]to the same materials every where to ensure one part does stick to another , it would be a bummer if that stuff lifted or bubbled up in say bright sun light ?

I though of cutting 4" strips of bed sheet and using that on all edges and joints before I tackled covering the bigger flat surfaces .

Quite excited to think this could actually become the real thing , even if only for one winter it will be useful to iron out the bugs in the design and me adapting to live with a large resonant box fastened on the back :D

Lots more ideas bubbling up for the mudguards and the lid.

Paul
 
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Hi Paul,
You will have to close off all the exposed edge to keep ingress through to the inside cavities.
Recommend using brown parcel paper (or nylon fabric), dowsed in PVA thinned with water, several layers. This is what we use in aeromodelling on foam cores. It's pretty strong. I DO have experience of this. Also polyurethane is probably a good coating. (At least 2 or even 3 for good measure)
Again, aeromodelling, some fliers have by passed the doped fabric as it smells and use nylon and 3 coats of Wilkos floor varnish(!) (water based variety, not done this myself). But I do 'fuel proof my models in polyurethane, the old yatch varnish type, I can recommend it.
Also skinning the cardboard with nylon, ripstop nylon would minimise surface punctures and crease-cracks occurring.
BTW the last post of the Warrior build show a bench, I have to recoat that every year to look good, 3 coats polyurethane. Doesn't blister in the sun., but it's not black!
I would say your success will depend on stopping water getting in or else the cardboard will wick it like fury and soon come to its demise.
I say good call and definitely worth doing.
Last thoughts,
What about Fablon coating. Nice plastic marble effect or 'superman' printed (??) from B&Q etc. Probably expensive to do all the outside (alternative:=brown parcel tape, book covering plastic?).
How are you fixing it to the frame? Bolts & battens I presume. How do you prevent crushing?
Good luck
Martin
 
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Hi Paul,
You will have to close off all the exposed edge to keep ingress through to the inside cavities.
Yes I may try silicon sealant for that job

Recommend using brown parcel paper (or nylon fabric), dowsed in PVA thinned with water, several layers. This is what we use in aeromodelling on foam cores. It's pretty strong. I DO have experience of this. Also polyurethane is probably a good coating. (At least 2 or even 3 for good measure)
Yes done that however never got to fly it 😢
Again, aeromodelling, some fliers have by passed the doped fabric as it smells and use nylon and 3 coats of Wilkos floor varnish(!) (water based variety,
I have a Johnson product called Future that may be the same , however it does not feel very sticky compare to polyurethane varnish
What about Fablon coating. Nice plastic marble effect or 'superman' printed (??) from B&Q etc. Probably expensive to do all the outside
Yes cost and I doubt the adhesive would like to be outside in the sun for very long , can't beat wood glue or varnish !
How are you fixing it to the frame? Bolts & battens I presume. How do you prevent crushing?
Yes this has been taxi the old grey cells ...
I was thinking of a 3mm plywood floor underneath with out side floor and plywood being given 2 coats of varnish then stuck together with silicon sealant , then 3 battens width wise under the plywood and 3 thin battens on the fairing floor with lots little wood screws. In the hope that spreading the load over a large area will control the weight inside the fairing ?

Paul
 
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Ok Houston we have a [ big ] problem



Where the yellow line is I currently have bolted to the rear seat mount a piece of wood 19mm [ 0.75"] thick the clearance needed for the seat to not hit the rear fairing ?
WRONG !
The gap at A is then 30mm [ 1.25" ] and the wood now hits the upper part of the rear pannier rack stay when pedalling hard up a hill and on the occasional bump , SWMBO says when I am sat on the seat the gap reduces from 30mm [ 1.25" ] to 6mm [ 0.25" ] and when stationary I can push hard on the pedals and can get the wood to strike the stay.
I suspect the problem partially lies with having the 2 elastomers [ a Fevo bike/trike has only 1 and a rod end ] and where my CofG is [ blue line ] in relation to the elastomer placement ?
So should I :-
a) ignore it and space the faring further back ?
b) replace the front elastomer with a rod end bearing , probably killing most of the suspension effect
c) upper the stiffness of the elastomers
d) extend the rear of the upper seat mount till it almost touches the rear axle and mount the rear elastomer there ? [ that will really bugger up the fairing ]
e) other ?

I do think the current set up provides some comfort when riding it , however the rearward seat bobbing during hard pedaling is obviously robbing me of some power , and of course the pannier stay is now providing a stop it may move back further in real life riding ?

Paul
 
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Or move the rear elastomer as far back as it will go. If that doesn't work, still move it back with a denser (harder grade) elastomer.
Seems the seat isn't squashing down parallel (or is it), could it be rotating on the front squashing the rear one more.
On power strokes (not rowing) the push through the back of the seat reduces the gap.

Another thought, could you stand a packer under the rear(!) (sorry about that), if the rear elastomer is squashing more than the front. Try 3 or 4mm ply disc, see if you notice.


Martin
 
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Or move the rear elastomer as far back as it will go. If that doesn't work, still move it back with a denser (harder grade) elastomer.
Option D I do have some slighly denser ones to try.

Seems the seat isn't squashing down parallel (or is it), could it be rotating on the front squashing the rear one more.
When stationary and not pedalling I suspect this is happening possible because of where the CofG is in relation to the rubbers.

On power strokes (not rowing) the push through the back of the seat reduces the gap.
Yep

Another thought, could you stand a packer under the rear(!) (sorry about that), if the rear elastomer is squashing more than the front. Try 3 or 4mm ply disc, see if you notice.
Could do

Another though is to also move the front one as far forward as possible, that may help ?

Or live with it.

On another slightly connected note I have ridden the old Python Mk2 [ no tilting , wider rear wheels , seat lower @ 8" lower ]

Dreadful !!!
It has a rock hard ride where you can tell which side of a coin you have passed over , I have to lean out of the seat for fear of it tipping over and you are sat lower than a snake's nipples !

What's that all about , have I become soft in my old age ?

Paul





Martin
[/QUOTE]
 
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You have appeared happy at riding the trike as is so reinventing it to suit the box seems the wrong way round. You may well expend a bit of power in flexing the seat but you have only spotted that by the seat movement rather than because you are going slowly so the real world loss must be low enough to be no real world issue. Modify the box to suit the trike you have been happy with.
 
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You have appeared happy at riding the trike as is so reinventing it to suit the box seems the wrong way round.
My concern is that the front elastomer is being stretched to allow the seat to tip back so it is putting undue stress on it in a mode that may eventually cause failure.

You may well expend a bit of power in flexing the seat but you have only spotted that by the seat movement rather than because you are going slowly so the real world loss must be low enough to be no real world issue.
I don't have any power to lose 😢

Modify the box to suit the trike you have been happy with.
Yes however it would be foolish [ in my view ] to not take some steps to cure this seat rocking backwards if they involve very little re-engineering ?



Dale-rider sent me this [ very kind of him ] showing an estimation of the forces involved ?
So proposals
a) was to build a longer seat sub-frame [ the horizontal red bit ] and then relocate the 2 elastomers to the blue positions ?
b) move the front elastomer to the position of the front blue one and the rear one back as far as possible ?[ not far maybe 3 " ]
c) add a third elastomer where the position of the front blue is shown ?

Short term
  1. I added a large tie wrap in the front blue elastomer position , could not get it was tight as I wanted for a few miles it tamed the leaning back however i suspected it stretched and was only half as effective when back home
  2. the front elastomer is less dense than the rear , they need changing so they are both the same density and as stiff as I can.
  3. look to see if I can get more dense still with a M10 bolt ?
thanks for looking Paul

ps every days a learning day :)
 
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Ok isolated one of the problems , hopefully fix it tomorrow.

I ran Tilt#5 and Tilt#6 concurrently for a time to see which rode better , so they were almost identical to allow comparison I split the elastomers I had between them.
The result was both trikes had a 113kg elastomer at the front and a 203kg elastomer at the rear , obviously the 113kg was letting the seat front rise easily when forces were applied.
As Tilt#5 is currently dismantled I can add it's 203kg to the front of the seat sub-frame and see if it is strong enough to tame some of the pedal induced bobbing ?

all for now Paul
 
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Well this is getting like ....



The curate's egg ?

I now have upped the tilt resistance from:-
203 kg + 113 kg = 316 kg
to
203 kg + 203 kg = 406 kg

So what has it done ? well tilting needs more effort [ noticeable ] and the pedal induced banging of the wooden seat spacer on the rear pannier rack brace has changed.
Purely subjective however before the elastomer change I felt the collision behind the seat was the brace stopping any further movement rearwards of the seat.
now
I think the piece of wood only kisses the rack brace very lightly.

However this was only a few yards out the cul-de-sac and up a steep enough hill to feel it easily , a proper ride is needed.

Paul
 
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Well this is getting like ....



The curate's egg ?

I now have upped the tilt resistance from:-
203 kg + 113 kg = 316 kg
to
203 kg + 203 kg = 406 kg

So what has it done ? well tilting needs more effort [ noticeable ] and the pedal induced banging of the wooden seat spacer on the rear pannier rack brace has changed.
Purely subjective however before the elastomer change I felt the collision behind the seat was the brace stopping any further movement rearwards of the seat.
now
I think the piece of wood only kisses the rack brace very lightly.

However this was only a few yards out the cul-de-sac and up a steep enough hill to feel it easily , a proper ride is needed.

Paul
If you visit your local spiritualist church just open the door and throw a selection of elastomers in like hand-grenades. You never know, you may be able to strike a happy medium. ;)
 
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If you visit your local spiritualist church just open the door and throw a selection of elastomers in like hand-grenades. You never know, you may be able to strike a happy medium. ;)
Well maybe , however it is all a learning curve , I think i have identified the max tilt elastomer values and may [ after a test ride ] revise it downwards ?

Don't forget I am boldly going where no one else can be ar**d to go ?

Paul
 
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Hi all

Well it has been ridden.
Tilting ? as predicted it takes more conscious/physical effort to get it to tilt I suspect that eventually that will not be noticed.
it has not stopped the interference at the rear , however it has reduced it considerably.
An unexpected side effect is it is much easier to ride it no hands - not all the time nor as far as before tilting.

So plan B the rear seat subframe extension will be implemented , the parts are cut holes need drilling and welding needs urm welding ? however not soon as soon as I would like i am busy all this week😢
Paul
 
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Ok so holes drilled and anti crush tube made a little large so it could be hammered into place [ saves welding ] next up weld in inner sleeve for joint and cap open end of extension.

Pictures would be pointless so instead lets look at dabbling with fairing shapes ?



Current plan with a vertical back of 3 pieces however in the flesh I though it may look a bit boring and bulky ?



So another idea tried in cardboard was to slope the back outwards towards the top ?
So this one has the same base length however the top is 5" further back , doesn't sound a lot however the visual effect is quite dramatic ?
it has the added bonus of allowing easier access to the inside and allowing slightly longer things to be carried if required.

Neither of these have the top made for them yet , still working on the design of that , it has as many pieces as the main box at present !

Any views ? either or ?

Paul
 
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Ok so holes drilled and anti crush tube made a little large so it could be hammered into place [ saves welding ] next up weld in inner sleeve for joint and cap open end of extension.

Pictures would be pointless so instead lets look at dabbling with fairing shapes ?



Current plan with a vertical back of 3 pieces however in the flesh I though it may look a bit boring and bulky ?



So another idea tried in cardboard was to slope the back outwards towards the top ?
So this one has the same base length however the top is 5" further back , doesn't sound a lot however the visual effect is quite dramatic ?
it has the added bonus of allowing easier access to the inside and allowing slightly longer things to be carried if required.

Neither of these have the top made for them yet , still working on the design of that , it has as many pieces as the main box at present !

Any views ? either or ?

Paul
I prefer the top one, but I have no logical basis for this choice other than I like the look of it better.
 
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Hi all

breaking [ literally ] news

TILT#6 SUFFERS CATASTROPHIC MATERIAL FAILURE !!!



On the way back from mothers Tilt#6 had a material failure leaving it [ and me ] across the middle of a road junction with the trike like this.

Thinking a rod end bearing had come loose I dragged it to the pavement , however on investigation a piece of 3mm plate had been torn asunder.



This is half the upper rod end mount the part fastened to the rear of the trike by the rod end however the tab should be part of this !



It has not split across the hole , rather been torn across the plate ?



Shaken but not stirred I limped it back the 1/4 mile to mothers and called the wife to come and rescue me and the trike.
Only the second time I have been rescued in 9+ years of Python[ing.]

Obviously got to figure out a repair ?

May cut them both out and replace with some 4mm I have ?

Paul
 
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