6.8mm diameter stainless wire availablity for Conti Empress spring

A haven dedicated to manual espresso machine aficionados.
Paolo

#1: Post by Paolo » Jul 07, 2019, 11:50 pm

Can anyone help?

I have a beautifully restored Conti Empress that is destined to become a decoration because I cannot find an appropriate spring for it.
It was restored recently and a 6.8mm diameter coated steel spring was located and installed in it (marked as 7mm diameter on the website):-
https://www.tse.at/shop/product_info/ca ... igung.html

It worked really well for a while but parts of the spring plating broke down, came loose and caused rubbing between the outside of the spring and the piston bore, which led to pitting of the bore. Obviously, that spring had to come out.

I had some custom stainless springs made but the closest we have in Australia in wire diameters is either 6.4mm or 7.1mm. I have tried both and (this is sounding like the 3 Bears here).... one was too soft and the other was too stiff. The length of the spring is governed by its unsprung length (in order to install it onto the piston rod) but really limited by the amount it needs to compress to in order to have the lever lock when in the 'down' position.

Who would have thought that such a small difference in wire diameter would have such a huge difference?!

We don't have stainless 6.8mm springmaking wire in Australia.

I am hoping that someone in another country will be able to tell me if they have 6.8mm diameter stainless wire available...hopefully with the outcome of having some springs made that I can use.

maximatica

#2: Post by maximatica » Jul 08, 2019, 1:48 am

Have you tried a company that makes custom front fork springs for motorcycles?

If they make them for a large range they might have the wire you need and can possibly advise on how best to make them and coat them for long wear.

HTH.

Paolo

#3: Post by Paolo » Jul 08, 2019, 2:47 am

maximatica wrote:Have you tried a company that makes custom front fork springs for motorcycles?
Hi Michael,
Thanks for the tip. It was worth pursuing.

I found a specialist motorcycle spring supplier in Australia that lists 6.8mm wire springs. YAY!!!! :D
They said that custom springs of this size are manufactured and brought in from Europe...wouldn't tell me which country...BOOO!!!! :cry:


and would be around AUSD600 for a pair of stainless springs plus import duty plus GST etc......TRIPLE BOOOO!!!!! :cry:

There HAS to be a way of getting around this for a reasonable cost.

zubinpatrick

#4: Post by zubinpatrick » Jul 08, 2019, 5:40 am

The stiffness of the spring is not just a product of the wire thickness, but also of the wire hardness. The old spring lever machines had none plated steel springs so that is another way to go, although I get wanting stainless so that you can forget about spring corrosion.
You mention that the length of the spring is governed by its unsprung length and I question that. In a lever machine the compressed height of the spring is the governing issue as the turns/windings can lock you out of full down pull on the lever. Unsprung length can be pre compressed (SAFETY FIRST) during assembly.
Also some shimming of the spring end(s) (sized washer) may also be possible to increase the spring force, uncompressed/compressed length.

User avatar
truemagellen

#5: Post by truemagellen » Jul 08, 2019, 10:22 am

Stainless springs will not perform the same long term.

Have a steel spring made or buy again, cover in a light coating of food safe grease which is what everyone I know does to their springs. Ideally you would get it plated or treated before to also prevent corrosion.

If you are worried about rubbing people have wrapped with teflon tape but that is a lousy solution. Buy a thin teflon sleeve that rides over the spring and is length of compressed spring. Or get the spring coated in Teflon which is the ultimate solution.

If you want a spring this is the place
https://www.centuryspring.com/

sprint jinx

#6: Post by sprint jinx » Jul 08, 2019, 1:55 pm

I had a custom motorcycle shock built by century spring. They are a quality outfit. It would be interesting to hear if they could do this job for you and bridge my two favorite obsessions.