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Kevin Armstrong
6th October 2011, 21:29
It's always easier to modify something instead of designing and building it from scratch, and today Amazon were selling an Artek MTB disc brake setup for just under £14, including stainless 160mm rotor. Sod it I thought, and got one to play with.

Intention is to park the existing fairly chunky steel drum brake mechanism and drum, mounting the rotor onto the wheel via a cotton-bobbin flanged spacer, and the cable disc caliper on a couple of tabs on the fork leg. Should save at least a kilo.

First, does anyone know what the proper name is for the flat tab headed bolts that are typically used on kingposts to take the outer cable at the top? Two would make ideal mounts for the caliper in the fork leg.

Second, an MTB weighs maybe fifteen kilos with a rider of 82kg, and has two brakes, I'm proposing stopping around 220 kilos with just one, think the pads will just disappear?

If so, at least the disc and experience fitting it will not be wasted, anyone know of a beefier caliper?

Cheers
Kev

Ps

http://www.apse.com.tw/E/body.php?web=11&SNo=02&FNo=101

The manufacturer is APSE Enterprise Co. Ltd. and is Tawainese.

APSE ENTERPRISE CO. LTD.
No.54, Jhangma St., Sioushuei Township, Changhua County 504, Taiwan (R.O.C.)
Tel:886-4-7612127 Fax:886-4-7613428
Website:http://www.apse.com.tw/
E-mail Box: apse.artek@msa.hinet.net

Wally Hayward
7th October 2011, 09:25
If it's any help, some while ago I had been playing with a few different set ups.

1 problem I found was that manufacturers would not disclose technical details such as temp build up per joule input, max pad temp allowed, average pad wear etc.etc

I think you may be pushing it a bit with only 1 brake, although they would not be subject to semi continuous, or such prolonged operation as on a bike.

Most cable systems work out at about 0.8Kg per pair inc rotor and cable about 0.65kg

You can get "racing" pads for many systems, which help to obviate brake fade, but generally are not so suitable when used with cable operation due to the harder compound

Cable types
The Avid "bb7" type has found favour with a number of PPG types, although it is "single acting" and appears to suffer from needing continual adjustment with a system which I do not like.
Many of the single pot types, seem to suffer in the same way.....
Single pot systems can suffer from "stiction" in the caliper slide which could be "offputting" if used in an independant heel/toe set up.!

The IRD "Dual banger" is a better cable operated bet and tends to keep it's settings as is the Gusset Chute Mechanical Disc Brake.

Hydraulic

1 thing to watch is that some are "closed system" and although can be operated with the "master cylinder" in any orientation, can suffer from gradual self application in hot weather (no problem here as it's always BB^^%$£$£*& cold/emoticons/smile.gif
Others can only operate with the master cylinder in the normal "bike" position, otherwise they cannot recouperate.

The Shimano M596 hydraulic 2 pot seems a good performer at a reasonable price and I believe the Kid uses the Hope Mono 4 which is a 4 pot hydraulic system and rather expensive..
The Magura Julie HP (High Pressure) seems to have better stopping power for less effort

Although they have not yet been tried in anger, I have currently settled for the Quad QHD 4 "Axis" dual pot hydraulic as an ecconomical set up with self adjusting pads.. although a sealed system. (partly because I got them VERY cheap/emoticons/smile.gif
.

As an afterthought and not being a trike pilot, I wonder if it is a good idea to use a single brake on the front wheel?
I can imagine all sorts of nasties when braking with the front wheel miss aligned.

Dave Smith
7th October 2011, 15:40
Front brake is actually more efficient on trikes.
Rear wheels tend to unload and lock up, mostly on grass.
I can't imagine brake fade is ever likely to be an issue on a landing.
Unlike a motor vehicle, you only have a finite amount of energy to dissipate.
Also on a trike, you have a good aerodynamic brake in the wing (bar hard into chest...)
Dave

Wally Hayward
7th October 2011, 18:30
I did look at using Pit Bike brakes, but the calipers themselves weight about 0.6Kg and use a heafty rotor although some do use a 160 mm dia rotor, but as you are aware,the larger diameter the rotor the better:-).
There are a number of MTB 160 rotors available with different claims to "efficiency". However, there are 3 different "standard" rotor thicknesses used and of course thicker ones may not fit your calipers.

Mike Cowlishaw
7th October 2011, 19:06
Interesting .. my two recent 'steeds' (GT450 and MF) have front-wheel disc brakes, but no way I would think to be able to run up the motor against them. Handy for bringing the craft to a stop at the end of taxiing, but really would not think of using them at any other time.

Mike

Wally Hayward
8th October 2011, 08:31
Kev.. I knew I had seen a front wheel set up similar to the one you are proposing, although on PPGs.

http://www.believeaviation.com/Home_Page.html

Also

http://www.skysthelimitusa.com/index.html

Mike Cowlishaw
8th October 2011, 08:40
> GT450 has two main wheel brakes Mike, no brake on the front wheel.

Indeed. Typo --- I wrote just about the MF at first, then realised it was also true for the 450, added that and forgot to delete 'front'. Sorry.

Also true for the Ikarus: could never do a mags check at 3000 rpm unless on rough ground/grass.

Mike

Bill
8th October 2011, 11:47
Loads of disc brake units on http:/ulmtechnologie.e.catalogues.info/ page 74

mikesands
8th October 2011, 12:35
Kev Armstrong wrote: Brilliant input

I tend to use the brake to run the motor up against it, having a 750 metre home strip means it isn't used a lot otherwise. At that price I am happy to bung it on and see what happens, after all, the mounting for the caliper is a DIN or similar standard, so it can be slung for a better one if required.

The ideal would have been the little cable disc on my lad's Derby Dirt Kid 12 mini motocrosser, but he would have objected to that being pinched.

Lots of scooter brakes around but it is finding someone who sells them as a kit, I'd have been happier locating something designed to stop a motorised vehicle, the stand-off spacer will have to be designed to accept other sizes of disc rotor, so if this packs in I can hunt out a beefier one, or just refit the original drum brake rig.

There are lots of lovely billet alloy parts on the Magic trike, but the brake drum is a lump of steel plate, on a slower machine I'd have slung the thing altogether, but mine's too quick to feel happy with no brake at all.

All hints and tips welcome, this will fit on any SSDR after all

Kev
hmmm not absolutely true Kev. I got quite excited until I read the rotor diameter was 160mm. The wheel not including tyre on the Dragonfly is just 115mm.
bummer
Mike

Wally Hayward
8th October 2011, 15:09
If you are not aware, Pocket Bike rotors generally are 160,140 and 120mm dia, but the 120 mm ones are generally 3mm thick, instead of 1.75/2mm and so ensure any caliper you buy can accommodate the extra thickness.

Obviously the larger the diameter rotor the better the braking effort for any given set up, but you mentioned 2.5" ground clearance, I imagine the rotor will be close to the tyre sidewall, by it's very nature. May I suggest you consider the case when the tyre gets a puncture, especially if coupled simultaneously with a heavy nosewheel landing, I think there is the possibly of the tyre "bulging" out enough to distort the rotor, also if operating from grass with little ground clearance, grass can easily get "picked up" by the rotor, in both cases causing a partial/full "jam" in the caliper causing uncommanded partial/full braking effort:-(..
I would suggest that the rotor should not be significantly larger in diameter than the wheel rim.

Wally Hayward
9th October 2011, 09:22
Kev. with all that fresh air above the tyre, you could fit a complete Pit Bike/pocket bike wheel and brake systems and still have space for an "airbag" for additional safety:-)

Bob Hood
9th October 2011, 18:21
Kev, Wally,

Judging by the cost of pocket bike wheels and tyres, fitting the complete wheel, tyre, and brake unit might be the most economical way to do it. You also get a really cool looking three or four spoke alloy wheel instead of a converted wheelbarrow wheel, and if weight allows you could fit them on all three axles, perhaps unbraked at the back.

Best regards,

Bob Hood

mikesands
9th October 2011, 18:47
Thanks for the info Kev. If Mike C is right though it sounds like Ben has already incorporated a disk brake on the latest dragonfly/motorfloaters. Mine's definitely a drum brake (and pretty useless)
By the way the wheels on the Flylight stuff are definitely not converted wheelbarrow wheels - they are from the Mountain Board world made by Scrub, albeit at the budget end. It's possible to buy full carbon fibre rims and I would have done, but my drum brake wouldn't have fitted and I'm not practical enough to make it do so.
Mike

Kevin Armstrong
9th October 2011, 20:06
[quote=Bob Hood BMAA 3300]Kev, Wally,

Judging by the cost of pocket bike wheels and tyres, fitting the complete wheel, tyre, and brake unit might be the most economical way to do it. You also get a really cool looking three or four spoke alloy wheel instead of a converted wheelbarrow wheel, and if weight allows you could fit them on all three axles, perhaps unbraked at the back.

*oi Hood! converted wheelbarrow wheel? ;-)

John makes his own wheels, cast alloy with proper bearings inside, rather pretty too. Main gain is they are split rim, so a puncture in the field is easy to sort out with a couple of spanners, no heaving and tyre levers.

They do have 8mm bolts holding them together which is over the top, I swapped thebolts for 6mm with hard nylon pneumatic tube sleeves over to knock a few hundred grams off, it works well.

One item that could do with being in the handbook is NOT to just tighten up the wheel retaining nuts, to save weight the bearings don't have spacer sleeves between, so the nut is merely spun up to touch then split- pinned.

Kicking ideas around like this is great for advancing everyone's safety, thanks

Cheers

Kev

Bob Hood
10th October 2011, 05:55
Kev,

Please apologise to John for me, I was of course thinking more of our older trike designs when I wrote about the wheels. For instance, I hadn't noticed that the wheels on your trike are ally, and made the assumption (it is bad to assume anything!) that they would be plastic like mine.

Sorry!

Bob Hood

Kevin Armstrong
10th October 2011, 07:56
Goodness me no...4" plastic with garden cart needle rollers? That spec came from the days when you rigged out of a trailer and flew off a short grass strip. Nowadays you get directed all over miles of ruddy tarmac, so the spec. has had to grow into proper sealed roller bearings and so on. One prominent Chaser pilot has already asked about conversion to Ace boolers.

I sometimes wonder, with the freedom of SSDR whether instead of only offering a full aircraft and that's it, whether you could have a 'shop' selling wheels, tube, even a complete wing. Even Jezza Harris' ambitions to knock up his own meant he asked Paul Dewhurst whether he could buy the wings from that lovely little fixed wing Flylight had that seemed to fall through. That way, someone capable of making a trike could buy the wing and hitch it to theirs.

Anyway, part of the search for a decent little disc brake was to make sure you could get pads, or at least same replacement. If the caliper is bracket mounted rather than direct to the fork, the bracket can be amended to suit any design of caliper mounting bolts, so any old caliper could be substituted.

I think this outfit are a good compromise, a few £ dearer but they do all the pads and seem very efficient, have ordered a disc and caliper off them as well

http://www.funbikes.co.uk/Mini_Dirt_Bike_Brake_Caliper_Front(31).aspx

Kev

mikesands
10th October 2011, 08:51
I think you have hit the nail on the head Kev. If you look at kiteboards, mountain boards or indeed motorcycling, their worlds are full of little upgrade kits that you can buy - partly to make your equipment perform better but equally to look cool. Normal microlighting doesn't allow the manufacturer to cater to this human failing but SSDR does. I get the distinct impression that Ben and Paul probably think that anyone who wants to fit carbon fibre wheels or a disk brake must be a tit 'cause that's not what flying is about ....but hey it's my money and maybe I'd rather spend it with them than buying a new Arrow can for my bike :-)
Mike

Mike Cowlishaw
10th October 2011, 09:33
Actually Ben has rather a good eye for design, I'd say :-). Those colour trims .... :-)

Mike

Paul Dewhurst
10th October 2011, 10:23
hi Mike

Problem for us compared to the motorbike industry, is that we have a tinynweensy Market. lots of stuff we what to do and fizzing with ideas, but we just have one person mostly full time on the Dragonfly project ( plus other duties within the company) and maybe a sum of another .5 to 1 on average, person helping him. And that is for design, testing, materials procurement, cutting, drilling and managing all the other manufacturing processes, customer support, marketiing, sales liaison, and finance and service, repairs, and product development.

Against that context, we offer a really large choice of options - four wings, four engines, two basic trike specs and then lots of option variation for each.

In fact when I sit back and think about it, it is quite astonishing! and of course that's just the dragonfly.

We do appreciate your comments and suggestions and don't disagree, and are we hope pro active in moving in that direction.

We have the same with the Skyranger / nynja project and air creation, which again has less than two people to do everything, and 250 aircraft so far.

Generally is hugely challenging in terms of the array of expertise and multi skills needed in such a few people. - but we wouldn't have it any other way!

Paul

Kevin Armstrong
10th October 2011, 11:06
Paul Dewhurst wrote:

We have the same with the Skyranger / Mynja project and air creation, which again has less than two people to do everything, and 250 aircraft so far.

Mynga?
Daren't add a comment to that...;-) :rofl:

Here's the caliper I found, but suspect that the slow rubbing speed the pads will be designed for, will be swamped by stopping a 50mph landing with a 300 diameter wheel and a 160 diameter disc.
The pit bike caliper is 140 disc and meatier caliper, but then the saving over the iron drum brake backplate might be minimal after adding the disc mount onto the wheel.
Paul is right on commercial terms, but this is the second most fun I've ever had as a hobby, tinkering away, so will share the results.
Incidentally, the bike mount has some natty domed washers so that you can slacken and align the brake caliper correctly-easier on a square tube fork on the FL aircraft compared to my circular section ones. Might have to bore a hole down the middle of an alloy block and slice it lengthways to form a firm base-possibly bonded on.

Kev



Attached files http://cloudniner.co.uk/images/converted_files/106442=8065-artek-disc-and-caliper.jpg (http://cloudniner.co.uk/images/converted_files/106442=8065-artek-disc-and-caliper.jpg)

Paul Dewhurst
10th October 2011, 11:46
Quick nip back and a bit of post editing! It's not Freudian slip to do with build or handling qualities I assure you :)

SSDR does give the opportunity to indulge in ones personal fetishes, and modify accordingly, without having to persuade the manufacturer that it's a good commercial proposition to supply latex body fairings, or neon flashing wheel rims etc..

Disc brake is a classic - drum is an easy off the shelf item - we get them ready made for dragonflies courtesy of using mountain board wheels, and they are not expensive. Converting to disc means collating components from different manufacturers and making bespoke spacers, modifying forks etc, all of which can cost a great deal more in money and time. Resulting in significantly greater customer cost, and maybe a very small weight saving. SSDR pricing is quite sensitive, where there is criticism even when we are less than half the price of the most popular two seater. So it's a tough balancing act for manufactures to improve without adding too much cost.

No problem though for a fun DIY project, where time spent is pleasure and not an hourly rate.

Paul

Wally Hayward
10th October 2011, 11:46
Kev, if it's any help in your deliberations, the 4.5" AZusa drum brake weighs 0.84Kg complete, less the wheel adaptor

mikesands
10th October 2011, 13:10
.... so is Ben now fitting the Dragonfly's with disk brakes Paul? If so, can I retrofit one to mine?
Thanks
Mike

Paul Dewhurst
10th October 2011, 14:04
no Mike, I was commenting on Kevin's playing with the idea for his machine as a personal fun project, and why it probably wouldn't be sensible for us to do the same and why we went for the drum brake - and presumably why ace also went for a drum.

The economics are quite brutal if you apply any sort of normal business numbers to them - It could easily take 100 hours to sort out properly by the time it has been researched and tested and different components tried, and forks redesigned, brackets and changes drawn up in CAD for machining / cutting, and new jigs made for manufacture. That has to be costed at at. Least workshop rates so there nearly 4k. To be half sensible you would want to get that back in a year or so of production, and as we do about 20 per year, that would be £200 each! And half of what we sell don't have the brake option, or might opt for the simpler drum, which would change it to £400 each -plus of course parts will be more expensive and we would like to have a margin to make it all worth while.

That would be a proper business approach of course, and you can see that it's patently not a good decision if the numbers were like that, as everyone would think the price outrageous and no one would buy. but I hope it gives you a flavour of just how expensive simple changes can be with such low volume cottage industry we are, and you can probably see that we do it more for love than money, and don't look for those normal commercial return levels. And have to budget for much longer periods to get payback.

With tiny companies and super low volume niche sales our R and D has to be considered very carefully and our limited budget for it spent as wisely as we can

Paul

Kevin Armstrong
10th October 2011, 14:50
Orl Korrect, however Mike is switched on to motorbike accessory life, and has some pretty good plus points in his favour:-

1) A brake rig will fit anything; you can test it up for yours and offer the kit to anyone. Even if you just upgrade the Dragonfly to a disc, the existing owners form a market, even making the R&D worth the effort, perhaps. Two will even fit a fixed-wing or add more braking effort to a Tanarg for comps?

2) A wing also fits anything, (although hanging a Bailey Motorfloater off a Cyclone wouldn't be wise except on slow trim/back hangpoint).

3) An accessory shop is pretty useless when you have to do what you must, to be allowed to add a gadget on a permit microlight, but on an SSDR with a few kilos spare weight capacity available, only imagination limits the range. Propellers, Tundra tyres, extra quiet exhausts, baggage accessories, GPS/radio bracketry, larger fuel tanks,

To be fair, you and Ben Ashman are two of the most imaginative folk around, and my ancient Flylight map-board is pretty knackered but one of the most useful things I've ever bought.

Titanium bolt kits, windscreens, clothing that wraps the feet like a sleeping bag for winter, Silva Windwatch, super lightweight tie-down kits, by gum....

Kev

Dave Smith
10th October 2011, 15:28
Simplest and lightest brake I ever had is the one on my Hornet trike.
It's like a reverse version of the venerable XL/Q one.
It pivots from the top of the forks with a foot bar below the pivot (and below the normal footrest) and a bar that presses on the rear face of the tyre below that.
You press it with a heel, rather than a toe - as you would with the Peggy version.
It doesn't wear away the tyre significantly and is quite effective.
Not only that, but because the applied pressure is pushing the wheel forwards, it's directly counteracting the the forces wanting to push the forks backwards under braking.
I'd have thought something as simple as that is perfectly suited to SSDR weights.

Dave

Kirk
10th October 2011, 15:52
Paul Dewhurst wrote:
clipped...

With tiny companies and super low volume niche sales our R and D has to be considered very carefully and our limited budget for it spent as wisely as we can

Paul

Can't agree more.

For me its even worse, I have two Raven Eclipsers and unfortunately I find that I own 1/4 of the UK registered population of the beasties ... and we are within Section S so everything is not only uncommercial on quantity but must be certified.

For me I want to make significant changes to improve the aircraft and I will just have to accept that the Major Mod costs will sit with me (including drawings, manufacture, static test, test pilots, BMAA fees, new noise certificates etc) for the two airframes I will mod ... and will have to pay twice as BMAA charge MM fees for each airframe.

There is no way I will recover the time and expense for the changes unless about 100 someones want to have a new modified Raven Eclipser with my mods and is willing to pay - squadron of pigs flew past the window on that one!

If you go commercial in an ultra-low volumn market you have to insist on sticking to what you have tested and not chop/change all the time, we cannot expect the manufacturer to have new models every year.

At least in SSDR the owners can pottle around in the shed for a few hours and put out a what-if change on a component, they never NEED to document or test as the manufacturer does and of course they value their time at pretty much £0.00.

Paul Dewhurst
10th October 2011, 16:10
Tanarg already has three disc brakes Kev - how much more does it need 2 per wheel? :)

i am not disagreeing, and we are ahead of you on lots of the accessory stuff - we do a retrofit brake kit already, larger tank, baggage bags, parachute bags and chutes to go in them, custom fairings to order for the motor floater, manual or electric retracts, monopole fairings, radio aerial brackets, fuel gauges, foot throttle kits ( early ones just had a hand throttle), whole trike carry bags, map boards. two bespoke disabled modifications so far.

Surely the dragonfly has pretty much the most options and add ons from base of any SSDR trike? For want of a more flattering term, we are trying to milk it as best we can :) - within the one man and his dog company size limitation.

Paul

PS our latest version map board has an adjustable leg strap with only a short stretchy bit - = less 'blow up' when flying an open trike at speed. noticed this was noted in your article as a problem, so seems like time for a new one? - we take cash, cheque or all major cards...

mikesands
10th October 2011, 20:26
Paul Dewhurst wrote: no Mike, I was commenting on Kevin's playing with the idea for his machine as a personal fun project, and why it probably wouldn't be sensible for us to do the same and why we went for the drum brake - and presumably why ace also went for a drum.

The economics are quite brutal if you apply any sort of normal business numbers to them - It could easily take 100 hours to sort out properly by the time it has been researched and tested and different components tried, and forks redesigned, brackets and changes drawn up in CAD for machining / cutting, and new jigs made for manufacture. That has to be costed at at. Least workshop rates so there nearly 4k. To be half sensible you would want to get that back in a year or so of production, and as we do about 20 per year, that would be £200 each! And half of what we sell don't have the brake option, or might opt for the simpler drum, which would change it to £400 each -plus of course parts will be more expensive and we would like to have a margin to make it all worth while.

That would be a proper business approach of course, and you can see that it's patently not a good decision if the numbers were like that, as everyone would think the price outrageous and no one would buy. but I hope it gives you a flavour of just how expensive simple changes can be with such low volume cottage industry we are, and you can probably see that we do it more for love than money, and don't look for those normal commercial return levels. And have to budget for much longer periods to get payback.

With tiny companies and super low volume niche sales our R and D has to be considered very carefully and our limited budget for it spent as wisely as we can

Paul
Don't disagree with any of that ... it's just that Mike Cowlinshaw says higher up that his motorfloater has a disk brake :-)
Mike

Mike Cowlishaw
11th October 2011, 09:38
Mike, that was a mistake -- sorry, really made a mess of that post. My MF has a drum brake.

Mike

Kevin Armstrong
11th October 2011, 10:37
Paul Dewhurst wrote:
Tanarg already has three disc brakes Kev - how much more does it need 2 per wheel? :)

PS our latest version map board has an adjustable leg strap with only a short stretchy bit - = less 'blow up' when flying an open trike at speed. noticed this was noted in your article as a problem, so seems like time for a new one? - we take cash, cheque or all major cards...Gosh, sorry, thought it only had a nosewheel brake with that anti-dive front end geometry. Will ring up for a map board, I've got a bad combination; an open trike and high-ish cruise speed.

Back to brakes; had a bit of a stunner today; the chunky dirt bike brake and disc weighs 335 grams, the Bicycle version 357 grams!

Both are half a kilo less than the Asuza drum that Wally mentioned.

Mike was right, a 160 disc is a bit big, so the lot is going on my Trek to upgrade it from Vee brakes, and the 140 diameter dirt bike disc and caliper rig is going on the trike. It has adjustement jack screws for sideways alignment, which is nice

One caveat, when you put the trike on skates, it hits the disc, modified plywood triangle required.

Kev

Attached files http://cloudniner.co.uk/images/converted_files/106514=8071-dirt-bike-disc-140mm.jpg (http://cloudniner.co.uk/images/converted_files/106514=8071-dirt-bike-disc-140mm.jpg) http://cloudniner.co.uk/images/converted_files/106514=8072-mountain-bike-160-disc.jpg (http://cloudniner.co.uk/images/converted_files/106514=8072-mountain-bike-160-disc.jpg)

Dave Smith
11th October 2011, 11:27
Nice if you could laser cut an identical disc in alloy Kev.
Dave

Paul Dewhurst
11th October 2011, 18:30
Presumably that's with a spacer to add and bracket or two andsome boltsto connect all up. Will be interesting to see how it all adds up.

Paul

Paul Dewhurst
12th October 2011, 17:14
I have just weighed our Dragonfly drum brake bits at 250g. Complete with wheel, wheel bearings and spacers, but excluding tyre and tube, and axle, it weighs 650g.

Anyone doing a project and wants a light wheel and brake assembly, we are happy to sell bits.

Paul

Mike Cowlishaw
12th October 2011, 19:26
Must admit I'm not too happy with the (Motorfloater) drum brake. With the engine at 2700 rpm [about as low as recommended] on tarmac the aircraft accelerates. Small dabs on the brake have almost no effect, so really one has to do serious and almost continuous braking to keep the aircraft down to a safe speed. And getting to the end of the taxi and hence stop to turn needs full brake starting 60-70 m in advance. Lots of heat being generated there....

Hoping it will 'bed in' soon.

Mike

mikesands
12th October 2011, 20:04
Mine hasn't got any better Mike - if I'm taxy-ing down wind I often have to run off the tarmac on to the grass to keep the speed down.. I did look at mounting another drum brake on the other side of the front wheel. They are supplied by the MTB people in pairs. Me not being an engineer I couldn't see how to do it, but if the gubbins would only add another 250g Paul, it might be worth offering a 'double' brake as an option.
Mike

Paul Dewhurst
12th October 2011, 20:35
We haven't actually got one on our demonstrator just now! But Ben assures me they bed in enough to lock the wheel on grass. Will pass the comments on.

Maybe a change to give some leverage advantage will help.

Paul

Kevin Armstrong
13th October 2011, 08:09
Thread was started because looking at the chunky drum that was fitted to the Magic, it was assumed it 'must' be possible to lighten the assembly using sexy alloy off the shelf bike parts. Feel like I've wasted everyone's time reading this.

Conclusions are:-

*Existing brake is hefty but works well; pull full revs on the 40bhp 447 and the only issue is the tyre skids along on the grass, good enough for power checks though.

*If you are a tinkerer and know what you're doing, you can carefully drill the drum between the holes and around the unused portion of the rim, shave any excess meat off the backplate if you like, but this only retrieves maybe one hundred grams.

*The drum has one advantage, it isn't vulnerable to damage when putting the front wheel on skates.

So I'm just going to end up with the same end result, a brake that works, for other Magic owners I'd maybe sling the drum altogether on the slow soaring stuff to save weight, but for the 447 powered trikes I'd leave it alone. Having taken the bloomin' thing to bits and done the drawings, may as well finish the job and see what it ends up like.

Mind, if the weather's good enough to fly on my day off that drum rig is getting slapped back on pronto...

Cheers

Kev

Kevin Armstrong
15th October 2011, 08:14
Dave Smith wrote: Nice if you could laser cut an identical disc in alloy Kev.
Dave
True, the discs are stamped rather than lasered out, I wondered why and was put right by one of the office lads who is ex fabrication shop.

Apparently lasering such a thin 2mm plate would cause heat distortion, so they are stamped and then ground flat afterwards.

Only disappointment is that the bicycle unti is stainless and the dirt bike one looks like something less posh. Might look round for a snazzier three-hole disc, have sorted the brackets and boiled the fit down to just two plates (lasered out of 5083 marine quality alloy).

Laser is great, just CAD up the bits, save it as a dxf and mail it to them to stick in the big machine, they have 2mm and 4mm on stock.

What a sad person...only regret is I haven't really improved the standard drum setup that came with the Ace trike, that can lock up the front wheel when braking on grass if pressed hard enough.

Cheers

Kev

Paul Dewhurst
15th October 2011, 13:49
we get most of our stuff water jet cut. similar price to laser and no heat problems. Very neat edges too.

paul

Kevin Armstrong
16th October 2011, 05:34
Paul Dewhurst wrote:
we get most of our stuff water jet cut. similar price to laser and no heat problems. Very neat edges too.

paulI bow to your superior memory Paul; clean forgot about water jet. Wait 'till I see the lad in the office; p*ss will be taken...

Interesting that the laser people can only cut 5083 (marine grade), apparently other grades reflect too much, must ring round to see who does water jet locally, although all the discs I've seen have been surface-ground flat afterwards, so even water might not be suitable to create your own discs. Handy for cutting plates from other grades of alloy though, thanks for that tip sir.

Another development thought:- A dirt bike will have much larger radius wheels, which will mean the disc having relatively slow rotation and the brake having lower torque to cope with. This may mean it will be too powerful with 300 outside diameter tyres.

Cheers

Kev

Mike Cowlishaw
16th October 2011, 07:08
> must ring round to see who does water jet locally

http://www.onestopwaterjet.com/?

Wally Hayward
16th October 2011, 08:07
Kev.. although related to their brakes, you may find the Matco data useful instead of having to calculate every comparison
http://www.matcomfg.com/how-to-choose.html

Bill
16th October 2011, 10:28
I haven't the faintest idea how much the water jet cutting process costs - anyone, and do they accommodate small one off jobs ?

Wally Hayward
16th October 2011, 14:59
Kev
Is it not the case that by whatever means you use to cut the rotor, you will need to surface grind it afterwards, irrepective of any distortion due to the cutting action.
Imperfections, even in a ground rotor are used so that the rotor will "kick back" the pads, thus any "real" surface imperfections such as those normal on the surface of a sheet will cause to brakes to feel "spongy", or in extreme cases very ineffective.

Paul Dewhurst
16th October 2011, 20:28
Water jet cutting prices are based on a number of factors. There is a set up fee, and any work on the drawing that might be needed - depends on file type you give them, and there are some considerations that are not immediately obvious. then it's priced by number of stop start cuts and length of cut. Also if they source the material there is that cost, which may incur a minimum charge, and depending on the shape, is determined at the amount of parts you can get out of a sheet.

So not so simple to work out! But pretty much the same considerations for laser cutting.best just to send them a drawing and ask for a quote.

Water jet much better for aluminium, especially thicker plates of 3-4mm, which the laser doesn't do so well at all - which is the main reason we switched on dragonfly manufacture.

I had the trophies for EMC last year water jet cut from brushed stainless, and was gobsmaked at how well they cut out the edges and detailed lettering. Absolutely no finishing required afterwards - full mantlepiece standard!

Paul

Kevin Armstrong
17th October 2011, 23:34
Got the laser stuff back today, not totally accurate; this was a big surprise as I'd measured using a digi caliper and CAD drawn the parts, so will try that water jet outfit.

Key issue is whether the company have your particular spec of alloy and required in stock, if so they will bung a couple of copies out for cash. I always get at least two cut when prototyping in case I screw up the finishing off operations.

Anyway the brake works, but is within one gram of the weight of the Ace drilled drum brake original...;-(

Waste of time, but fun and you learn each time a little more.

Kev

Attached files http://cloudniner.co.uk/images/converted_files/106905=8088-forks-complete.jpg (http://cloudniner.co.uk/images/converted_files/106905=8088-forks-complete.jpg) http://cloudniner.co.uk/images/converted_files/106905=8089-adapter-plate.jpg (http://cloudniner.co.uk/images/converted_files/106905=8089-adapter-plate.jpg) http://cloudniner.co.uk/images/converted_files/106905=8090-elevation.jpg (http://cloudniner.co.uk/images/converted_files/106905=8090-elevation.jpg) http://cloudniner.co.uk/images/converted_files/106905=8091-parts.jpg (http://cloudniner.co.uk/images/converted_files/106905=8091-parts.jpg)

Mike Cowlishaw
18th October 2011, 06:47
Certainly looks smart!

Kevin Armstrong
18th October 2011, 07:18
Thanks Mike, I don't like that wavy edged disc, might ask the company if they have any plainer ones, more 'aero' looking.

The holes for the disc spacer bolts are better moved round a bit, this makes for a more compact mounting plate.

Funny thing, saw a plastic Thruster nosewheel with the same or similar rim clamping bolts, so the disc rig could be used on other SSDRS with split rims, just need to adjust the pitched circle diameter of the plate.

Cheers

Kev

(bolting it on today)

Attached files disc-brake-model-1.pdf (http://cloudniner.co.uk/images/converted_files/106911=8092-disc-brake-model-1.pdf) (22.7 KB) disc-brackets.pdf (http://cloudniner.co.uk/images/converted_files/106911=8093-disc-brackets.pdf) (13.6 KB)

Dave Smith
18th October 2011, 12:06
Wonder if a single large diameter tubular section spacer might be lighter than your three spacers (which have to be meaty to withstand the torque)?
Dave

Wally Hayward
18th October 2011, 12:34
Kev I guess you are using the 3mm "Dirt/Pit/Pocket" bike rotors which are heavier than the MTB ones.?
As to the "wavy" rotors, according to Galfer USA who claim to have "invented them"....

Quote

"Patented inner and outer Wave® design minimizes heat transfer, equalizes dissipation and evens out pad wear"

and
"Keeps brake system cooler by allowing air to pass over every point of a brake pad surface"

Which I guess is why the majority of manufacturers use similar designs.

Kevin Armstrong
18th October 2011, 16:37
Wally Hayward wrote:
Kev I guess you are using the 3mm "Dirt/Pit/Pocket" bike rotors which are heavier than the MTB ones.?
As to the "wavy" rotors, according to Galfer USA who claim to have "invented them"....

*Hello Wally

The rotor that arrived was 2mm thick, and actually the same weight as the pushbike item (see earlier post)

Update; fitted the stuff today, all worked very well until I gave the footpedal some welly and the caliper stripped the screw threads in the body, holding the two halves together!

Grrrrrrr. Trouble is, the caliper is designed to work with a hand lever, not a foot-pedal.

So drilled the bolts right through, fitted nuts on the outer casing, and carried on, muttering words similar to 'heck' and 'fudge it'

Chinese alloy is like finest soft cheese, and the screws through the body were not over-long, I rang the suppliers and they immediately and without question despatched a replacement, so treated myself to a 6mm Helicoil kit, and am going to upgrade the threads with harder wearing helicoils inserts and longer set-screws. Anyone else want this doing, happy to help.

cheers

Kev

Wally Hayward
18th October 2011, 17:18
Kev...... lighter wellies might be the answer:-)

Mike Cowlishaw
18th October 2011, 18:35
Hmm, I see helicoils in my future ... any recommended UK supplier?

Mike Cowlishaw
19th October 2011, 16:47
Very kind offer, thanks. Don't need it at the moment, so hang on to it for now. I think I may have overtightened a bolt, however, will keep an eye on it ....

Mike

Kevin Armstrong
19th October 2011, 17:52
Mike Cowlishaw wrote: Very kind offer, thanks. Don't need it at the moment, so hang on to it for now. I think I may have overtightened a bolt, however, will keep an eye on it ....

Mike
*we've all done it, two solutions I use:-

1) find a set screw (threaded all the way up) and wind it in finger tight as far as it will go, then gently run it to the limit of the threads with a spanner. Very gently. Compare the depth of insertion with the screw or bolt that you originally had in there and see if you can sneak a longer one in.

2) use Allthread ( also known as stud -iron colloquially) and two locknuts on it, again wind as far as it will go into the casing or casting, then junior hacksaw off at enough to take a Nyloc, washer and a couple of spare threads. If it is sealing a casing pop some blue Loctite in there first.

Good luck unless I'm teaching granny to suck avian foetuses?

Kev

Mike Cowlishaw
19th October 2011, 19:08
Good thoughts -- thanks. I'm no metalworker; not too bad with wood (or electronics), but never did more than basic metalworking.

Mike

Kevin Armstrong
20th October 2011, 08:24
Did the Helicoils las night, what a doddle, kit was made in Australia, cost £25 including special oversize tap, drill, tool(s) to wind it in, break off the insertion tail with a handy depth gauge. Nice touch the little punch you use to snap the tail off the Helicoil insert was magnetised to remove the tail afterwards.

So anyone doing this needs to spend £13-odd on the caliper, and £25 to upgrade the threads! Still, it works nicely now, just need the wind to die down a bit to try it out.

Cheers

Kev

sted65
20th October 2011, 13:06
So you lot know for the future, Helicoils are and always have been made in the UK. Try this site for a friendly and helpfull firm that will sell you just what you need and if you know what you are doing, you don't need a full kit, just a Tap and a couple of inserts (always get a spare). The tang can be removed with a tool made from a piece of rod.

WTI fastners are in Derbyshire. http://www.wti-fasteners.co.uk/

Kevin Armstrong
28th October 2011, 14:46
The original Helicoils around here were made by Armstrongs at Beverley, sadly no relation...

American invention

The Australian kit I bought worked well, it was only after purchase it was noticed that it was made not in the UK

The disc brake works by the way, beautifully (phew)

Kev


Ted Snook wrote:
So you lot know for the future, Helicoils are and always have been made in the UK. Try this site for a friendly and helpfull firm that will sell you just what you need and if you know what you are doing, you don't need a full kit, just a Tap and a couple of inserts (always get a spare). The tang can be removed with a tool made from a piece of rod.

WTI fastners are in Derbyshire. http://www.wti-fasteners.co.uk/

Wally Hayward
28th October 2011, 15:58
Guess the act that the Helicoil kit was not made in Uk was the reason it worked:-)

Glad to know your disc brake works well, gives me greater confidence that my proposed independent heel brake system will be ok on my 3 axis.