Looking for tubes.

[Guzrik]

I am looking for some steel tubes to make a hydraulic cilinder but I am not sure about the specific requirements.
Inside diameter has to be 20mm, outside 24 (which seems to be unobtainable) or else 25mm.
The inside has to be smooth enough, I think a normal hydraulic precision tube will eat my seal, so that it has to be h8 with Ra of less then 0.5?
Does anyone know what standard or code this would be?
Hope this will also help me locating a Dutch/German/Belgium supplier willing to send me a small quantity.

 

[8ob]

What you are looking for is pre honed tubing http://www.hydraulicsupplies.co.uk/

Bob

 

[grim_d]

Westminster is full of tubes.

 

[Seadog]

 

[mike os]

Any reason you want to make your own? I buy fairly regularly, usually made to order, and cheaper than I can buy the components. By the time you factor in the machining and welding it's hard to justify attempting your own

 

[Guzrik]

Any reason you want to make your own? I buy fairly regularly, usually made to order, and cheaper than I can buy the components. By the time you factor in the machining and welding it's hard to justify attempting your own

I reuse some mounting parts of the old one, space is limited.
Rest of the required components isn't very expensive, only this tube is hard to come by.

 

[zzr1200]

There's also these people, you can order tube by the mm in the UK, can't see why in Europe it should be different.

• The Netherlands
  Telephone: +31 (0)1625 81060
  Email: info@fpeseals.com

https://www.fpeseals.com/cylinder-parts_2

hth

 

[Guzrik]

There's also these people, you can order tube by the mm in the UK, can't see why in Europe it should be different.

• The Netherlands
  Telephone: +31 (0)1625 81060
  Email: info@fpeseals.com

https://www.fpeseals.com/cylinder-parts_2

hth

Only down to 25mm bore, but I will give them a call anyway, thanks.

 

[Guzrik]

And this proves even harder then I thought.
First I measured the original tubing an that is between 20.015 and 20.02 so H7. These tubes are crimped onto the cilinder head so need to be cut for disassembly making them too short to reuse.
I found a company who sold me two pieces that should be correct to use as cilindertube but on inspection these are -0.035, and the piston moves really difficult in these ones.
I am afraid the (PTFE+) seal will wear out fast.
Best I can buy now is H10 (+0.085), but not happy with such a big bore.
Anybody ever seen such small hones for sale maybe?

 

[8ob]

And this proves even harder then I thought.
First I measured the original tubing an that is between 20.015 and 20.02 so H7. These tubes are crimped onto the cilinder head so need to be cut for disassembly making them too short to reuse.
I found a company who sold me two pieces that should be correct to use as cilindertube but on inspection these are -0.035, and the piston moves really difficult in these ones.
I am afraid the (PTFE+) seal will wear out fast.
Best I can buy now is H10 (+0.085), but not happy with such a big bore.
Anybody ever seen such small hones for sale maybe?

20mm id rams seems quite freely available from a number of manufacturers, you should be able to purchase tube from them.

Hydraulic Double Acting Micro Cylinder / Ram| Flowfit

Hydraulic D/Acting Micro Cylinder/Ram 20Bore 12Rod 25Stroke 118Closed 71220/25. Competitive prices all year round, next day delivery available!

www.flowfitonline.com

https://ca01.smcworld.com/catalog/BEST-5-8-en/pdf/8-p1315-1333-chn_en.pdf

Bob