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Epoxy & Glues
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Nexus
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Epoxy & Glues

Looking for advice on what to use on a drive setup I have been working on.

In short want to glue a shaft into a gear to stop any wobbles.

Angle grinders use something like I need to glue the motor and shaft together.
Dont think araldyte is the best solution as it would have a little bit of force applied so nothing that will crack, but who knows.

Its not really for strength but just to keep things lined up and will be permanent.

The shaft has a D grinded out and the gear mates with this D shape but has a little play which I would like to eliminate as well as use the glue to set the gear in position so everything stayes lined up.

Any thoughts anyone?
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Post Wed Mar 23, 2005 4:59 pm 
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Glen
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there is supposed to be some flavour of loctite that is used to build up the diameter between shafts and bearings so you get a really tight fit on them, im guessing you could use the same stuff there,

but i wouldnt go past the good old 5 minute epoxy, thats pretty good stuff. of all the glues ive used it was the strongest in keeping wheel tread on (no relation to your job obviously Smile)

id also like to know if theres a glue you can use to stick polycarb and aluminium together
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Post Wed Mar 23, 2005 5:25 pm 
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kkeerroo
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I have a question that someone else might know more about than me.
I am looking for a cold castable polyurethane (?) type rubber which I can use to make my own wheels. I have been doing some research into castable elasto-polymers for work but it is not at all suitable for wheels. I like the idea of making my own hub, dropping it into a mould and pouring in the rubber. Any suggestions?
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Post Fri Apr 29, 2005 12:22 pm 
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Spockie-Tech
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sounds like a question for Jake & Co. Isnt that what they do with their "Squidgy wheels" ?
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Post Fri Apr 29, 2005 1:16 pm 
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timmeh
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I would like to be able to do the same and make my own belts mainly for small robot and the odd wheel or so but havent ben able to find where to buy the stuff or much info on how to use the stuff.
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Post Fri Apr 29, 2005 3:59 pm 
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Nick
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Jake knows the most about urethane wheels but its a closely guarded secret about his supplier.

Have a look at http://www.itw-devcon.com.au/driver.asp?page=main/products/product+catalogue/flexane+urethanes . Flexane 80 looks promising, although it seems more expensive than the stuff Jake uses. They also have some good technical guides if you dig deep enough.

@ George: Those little D shapes are called Woodruff keys, they seem to be a standard on angle grinders. If the gear is a good fit on the shaft but can turn axially, then the key is a bad fit and it will wear unless its replaced with a thicker one. If the gear is a loose fit on the shaft & wobbles about, you could build the shaft up with a metal shim or try the Locktite bearing retainer http://www.loctite.us/int_henkel/loctite_us/index.cfm?pageid=10&layout=1
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Post Fri Apr 29, 2005 4:19 pm 
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Knightrous
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quote:
sounds like a question for Jake & Co. Isnt that what they do with their "Squidgy wheels" ?


I don't think Jake & Co will give away their trade secrets Razz I wouldn't mind learning about this urethane rubbers too, I'm more after a rubber compound like the Volcalon used in the UK
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Post Fri Apr 29, 2005 4:20 pm 
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kkeerroo
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If it helps to get a more sensible answer than "ask Jake" the stuff here at work is called Conathane Tu-4010. When cured it closely resembles the stuff that rubber bands are made from. What is confusing me is the grades of hardness, eg "50 Shore A". Any sensible answers?
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Post Fri Apr 29, 2005 5:51 pm 
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Glen
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some grades arent suitable for use on tyres, hence why the squidgy wheels are made from a harder mix in the center for rigidity and a harder one on the outside for the traction.

nfi what the technicals are but the stuff comes from a place up the road from me and you just vary the amount of isocyanate and polyol to get different hardnesses.

get the book kickin bot by grand imahara first though, its got a little bit about hardnesses on wheels.. to much to type but it basically states that 50 shore A is what the ideal traction compound is, i guess search for the shore scale on google.

as a guess the inside polyurethane on my wheels is extremelly hard, you cannot compress it and most of you have felt the outside stuff.
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Post Fri Apr 29, 2005 6:02 pm 
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Nick
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Here is a cool diagram on the hardness scales:



From the various catalogs and robot web sites, it looks like 60 to 80 Shore A is the prefered range. The Flexane data sheet shows it can vary right across that rane with the flex-add modifyer: http://www.itw-devcon.com.au/pdf/technical/flexane%20urethanes%20tds.pdf
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Post Fri Apr 29, 2005 6:18 pm 
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Nick
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I notice that Colson and Whyachi wheels are 65 Shore A, while NPC wheels are 70 Shore A. IMHO, the NPC wheels I have are a bit too hard.

Jakes wheels seem softer than the others and while they wear fast, they have improved Jolt outa sight Smile. At a guess, Jakes wheels are in the 50 to 60 Shore A range
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Post Fri Apr 29, 2005 7:35 pm 
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Glen
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jake and i measured mine last weekend, from the initial 98mm there down to 95mm, as opposed to red wheels going from 95mm to 90mm in one event hehe.
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Post Fri Apr 29, 2005 7:38 pm 
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the moth
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Obviously no-one is aware that polyurethane molding is toxic and dangerous !!!
I have substantial experience in polyurethane molding , having run the product development area for Henderson’s plastics (Melb) in the late 80's . Polyurethanes are made from two basic chemicals with a (very) small percentage of stabilizers added to control the reactions .

Polyol is basically inert and posed no recognized danger when I left the industry in '88

Isocyanides on the other hand are quite dangerous , most known for causing respiratory failure similar to a massive asthma attack . The clue here is the name iso-CYANIDES , they come from the same family as CYANIDE . Some versions start to vapor at room temperature and others need to be slightly heated - but none are safe . In the case of Tdi - it vapors at room temp and if you can smell it - you are already 600 times over the safe fume level for a 8 hour day . Make no mistake this chemical is dangerous . Polyurethane related deaths come in two flavors – Painfully fast or agonizingly slow . E.g.: If you work for years surrounded by fumes that you can smell you will develop respiratory problems and may slowly die . If you are involved in a large “spill” and inhale strong fumes for 2 hours you may not make it to the weekend . Because of the nature of the symptoms – doctors often mis-diagnose the problem , believing its only asthma . Often data sheets are intentionally vague and many companies have avoided their responsibilities by blaming deaths on asthma or other respiratory problems .

Because of the danger : polyurethane molding should be only done in a approved and well vented area , and you should never breath the fumes . Polyurethanes are present in many things : 2pac paint , some floor coatings (caused 50 deaths in London underground fire ) ,some packaging systems , sealers etc .
DO NOT play with these chemicals unless you know what you are doing – the ramifications may not present themselves for many years .
Sorry to be the “Bringer of Doom” on this subject , but I suffer respiratory problems for what I did in the late 80’s
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Post Fri Apr 29, 2005 8:59 pm 
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Nick
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Everyone should read: http://www.itw-devcon.com.au/pdf/safety/flexane%2080%20liquid%20resin%20msds.pdf

And: http://www.itw-devcon.com.au/pdf/safety/flexane%2080%20liquid%20curing%20agent%20msds.pdf

If you are in any doubt about he above posting. I don't know which one is worse; they both sound evil. Would an activated carbon mask go some way to lessening the effects? Another other 'trick' I use in these cases is to do the work outside and standing in front of a strong fan to make sure any gasses are blowing away from me.
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Post Fri Apr 29, 2005 10:01 pm 
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Valen
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seen the MSDS for sand?
http://www.jtbaker.com/msds/englishhtml/s0722.htm

I think we are about 60 Shore A give or take.


the supplier isnt secret, i just cant rember their name, just how to get there lol.

the msds for those seems to indicate its fairly benign, they may have changed the mixing since "the moth" did it also the quantities we are dealing in are probbly somewhat different, i think we have gone through about 6 liters in about 6 months which is different to working with the stuff full time.
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Post Sat Apr 30, 2005 12:11 am 
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