Which plastic to use.

here are a few charts on plastics

**LINK**

think i'd go with delrin

Edited By jim' on 20/09/2014 02:39:17

Jeff,

I bow to your wisdom.

MichaelG.

Peter,

If you actually contact e-spares http://www.espares.co.uk/contact/sales they will get back to you very quickly.

Just did the same thing for my Hotpoint washing machine drum bearings.

Unfortunately for me the answer was not what I was looking for - the whole drum assembly has to be replaced as the bearings are moulded into the outer casing

Not good for a machine just over five years old.

Hi Jim

That's an excellent comparison. It's bookmarked !

Delrin is a type of Acetal from Dupont. I think slightly better strength and doesn't squeak as easily but slightly worse temperature and chemical resistance on average. But for Peters application it would be as good as anything. And bog standard acetal would be good as well.

Cheers Will

Peter,

I don't want to labour the point but I didn't supply a very good link to c and m spares. If you got the bottom of page two of the link I gave, there appear to be four different styles of Zanussi wheels available. From the details, they seem to fit hundreds of models. I can't think that they would go to the trouble of, literally, 're-inventing the wheel' each time they redesigned or produced a new machine. Anyway, good luck with your search and keep wearing the rubber gloves!

John

I agree with Jeff Dayman above, my own experience with simple wheels in Nylon 66 has been, as I said earlier, without trouble for better than 5 years.

The old wheels failed from becoming brittle, they actually crumbled when I stripped them out. As for worrying about hygroscopic effects, forget it----this is a dishwasher.

Drill the bores a little oversize if you must to give a sloppy fit on the axles, I just used the nearest drill size for a comfortable fit. The job took a shorter time to do than all this agonising.

Peter You were concerned about fumes from PTFE. That only becomes a problem if the stuff is exposed to flame, it will then release flourine which is NOT nice. PTFE is the abbreviated name for Poly Tetra Flouro Ethylene

Brian

Zanussi? absolute garbage, bought SWTSMBO a microwave from them, only lasted 24 years. Failure? Stupid screen printed wiring to touch pads. Is nothing built to last?

Regards Ian

.

Brian,

Two questions, if I may ...

1. Do you know what material the OEM used for the original wheels ?
2. Any ideas as to why 'they' don't use Nylon 66 ?

I have a genuine interest, albeit only academic [because, in our house, I am the dishwasher]

MichaelG.

I forgot to mention that much of the plastic I have seen used in home dishwashers is mineral filled polypropylene. Usually the filler is 10 to 20% talc (calcium carbonate).

This resin is used because it is very inexpensive for the manufacturer, looks nice when the appliance is new, and does a good job for a period of time. It will eventually degrade with use in hot water and detergents though.

Michael G- I only claim practical experience and some success with these matters, to gain some wisdom is a goal for the future!

JD

John H.

I had a look at the C&M site again. The very first item, for AEG, appears to have the wheels that I want, but I don't know about the size. But, looking again, I notice that the exact same item is also shown for Tricity/Bendix and Zanussi. I need to measure and then contact them.

For obvious reasons, if I can buy ready made, even if it involves some dismantling to get the parts I need, that is my preferred way to go.

The two gentlemen who sent PM's.

All noted, and thankyou very much. As I've said to John H., I really do prefer to buy readymade if possible.

There is just one other point which is always at the back of my mind, and that is that strictly speaking I shouldn't even be attempting to do this as the property is rented and the dishwasher, being built-in is therefore owned by the landlord. However, as my daughter is disabled following a serious accident 13 months ago, I, as you will realise, wish to assist her as much as possible, and if by repairing things like this it avoids any problems with getting the landlord to repair it, then I'll do it. I mentioned the built-in fridge - that was a broken glass shelf when a pan got dropped on it. £23 later, a new, thicker shelf, and who's to know? Similarly, the other day I tightened most of the cupboard & drawer handles in the kitchen. Again, it saves problems and who's to know now that I've done it? Therefore, in the current situation, if by buying, rather than making, a set of suitable wheels, even if it means some dismantling and reassembly, it gets round a problem then that's what I will do. And even if I end up having to make them, then as long as it works, then again, who's to know? From what I hear, I don't think there will be a problem with the owner anyway. The property is owned by a local farmer, miles out in the country, is situated next to the farm and has, I believe, been built pending his retirement which is a long time off. It's hardly a professional letting business although it was let via a local estate agent.

Gentlemen, it's been an interesting discussion, has it not? I thank you all for your help and assistance. I will report back when I've sorted out what's what, but until then....

Regards,

Peter G. Shaw

Michael G

---Two questions, if I may ...

1. Do you know what material the OEM used for the original wheels ?
2. Any ideas as to why 'they' don't use Nylon 66 ?

In answer, I don't know what the manufacturers used but I suspect Jeff Dayman is correct with body filled polypropylene. I remember the brittle remains of the failed wheels being chalky which would square with what he says. As to why, cheap materials and speed of manufacture would I think be the answer.

All I did was take rough dimensions and make the replacements, then chucked the failures away. They are crude with bores that run on plasti-coated steel pins on the tray tackle inside; I imagine that itself is to similar spec. as a supermarket trolley

Peter. Final comments really, but who is to know or even care if you fix things for your daughter, most landlords welcome a peaceful life and really wouldn't want to be bothered with what they might regard as a trivial problem, certainly if it costs them money. What the eye doesn't see .....and all that. More power to your elbow.

Regards Brian

.

Thanks, Brian

That closing sentence says it alll, I guess.

MichaelG.

Hi folks,

As promised, here is the final result.

I contacted C&M Domestic Appliances and spoke to a very helpful lady. After she had discovered that I was using the wrong term – it should have been “Basket Wheel Support”, or possibly “Castors” - she then confirmed that the wheel sizes were indeed the same as my one remaining original. I then orderd two sets as I needed four wheels, on the expectation that I would be able to easily transfer the new wheels onto the existing support bracket. The photo below shows one of the items I ordered along with the old wheel.

Unfortunately, I foumd that the wheels were not easily removable, and there was no indication as to how they were fastened on. A quick trip to my daughter revealed that the support bracket was also wrong. Incidently, on another website, there was indeed a set of components one of which looked very similar to the support bracket on my daughters machine, but there was also a note warning people to be very careful as removing the bracket would involve the loss of an additional plate between the inner and outer skins of the dishwasher thus making the job somewhat more difficult. A final consideration was the cost – the kit of parts was around £18, or £36 in total, whereas the bits I bought were only £6.18 each.

In the end, I decided to deliberately break one of the new pieces. First attempt was to see of there was a push in piece holding the wheel in place. Heavy hammer and bar resulted in the stub axle breaking off – see photo below. Next, I attacked the wheel with a junior hacksaw and this revealed that the wheel was held on effectively by a flexible plastic lip on the inside of the wheel which locked into place over a matching protrusion on the stub axle. See the drawing which shows both the old wheel, and a new wheel. This also showed that I would have had no chance of making new wheels as I don't have a narrow enough tool to create the gap, about 0.5mm, between the lip and the wheel body.

Note the difference between the old wheel on the right, and the new wheel on the left.

So, having found out how it located, I then drilled out the stub axle on the second wheel until it came free, compared the broken stub axle with the existing, fortunately the same, placed the new wheel in position, pressed hard and with a very satisfying click, the wheel locked into place. Job done.

Of course, having deliberately damaged one of the new wheels, I then had to buy another set, but at a total of £18.54, I have satisfactorily repaired a 25 year old dishwasher.

Final comment. My daughter, says that she is going to tell the owner what I have done on the grounds that it shows them to be good responsible tenants. Hmmm, I do hope she isn't letting herself, me(?), into more jobs around this rented property!

 So there we are, job done. Many thanks to all who contributed.

Regards,

Peter G. Shaw

Edit. How do I change the text size? The original pasted in from Libre Office Writer which is effectively the same as Word, but on the forum, was quite large, yet on the original,was reasonable. In the end, I have had to resize in Libre Office and then copy and paste again.

Edited By Peter G. Shaw on 01/10/2014 11:55:09

Glad it worked out well Peter. JD

I used to use PEEK in injection Molding years ago. We made electrical connectors and rollers for inside cash point machines with it. It's very hard and the nozzle temperature was around 450c to ensure good flow through the mold. The mold was also heated with an oil heater to around 120c IIRC.

So slightly overkill for this use, but then again so was connecting my fishpond to the central heating in the house.

Talc Filled PP should be fine as we used to make millions of kettle filter with it. Personally I'd use Delrin / Acetal.

I agree with the OTTness of PEEK. Acetal is the way to go.

cheers

Bill

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Please, Chaps, let's move-on

The job is done, and Peter is happy

All I said was that PEEK is probably the best "engineering plastic" and available cheaply if you know where to look.

MichaelG.

Very last word from me.

Last Sunday, my daughter says: "Is now a good time to say that all the wheels on the other side have come off?"

'ere we go again!

Peter.