Still Stupid after all these years.

[slow-poke]

I found these ones... perhaps. https://www.aliexpress.com/item/100...202305142100591486453136783920014382173_1&s=p

Thanks for that Janger. Seems like it would be worth the cost and effort.

I just need to decipher the 20-250-40-28

Best guess so far, all in mm:

20 is small end diameter?
250 is length?
40 is # of spirals?
28 is large end diameter?

perhaps last two should be flip floppe?

Please help me out

 

[DPittman]

Thanks for that Janger. Seems like it would be worth the cost and effort.

I just need to decipher the 20-250-40-28

Best guess so far, all in mm:

20 is small end diameter?
250 is length?
40 is # of spirals?
28 is large end diameter?

perhaps last two should be flip floppe?

Please help me out

Hmnn I'm guessing that maybe 40 is the large end and 28 is the # of spirals? Typical Aliexpress- never really sure what the hell the specifications of the items are.

 

[Ironman]

Thanks for that Janger. Seems like it would be worth the cost and effort.

I just need to decipher the 20-250-40-28

Best guess so far, all in mm:

20 is small end diameter?
250 is length?
40 is # of spirals?
28 is large end diameter?

perhaps last two should be flip floppe?

Please help me out

Small End - 20mm - Extended Length 250mm - Compressed length 40mm - big end 28mm
When you order give yourself some extra, you can always zip cut it if it is too much but if you need 30 inches, make it 34 so you still have some slight tension at full travel.

I did the 'measure the ends' when I started to mount these. I threw out the first attempt, as I found the diameters are not constant and vary with use. Then I did some research and found out the best thing is to be loose, and allowing much more room than you think you should. Here is a sheet I downloaded that should help you out. The internal guide is way more important than a outer cup. And one end needs to be anchored to prevent the whole thing rotating in unison with the lead screw when the spring is extended a lot. Best material for the cup and pilot is nylon, or aluminum.

 

[Janger]

I’m not sure how these springs work. Is the at rest position fully extended? What keeps the spring from turning into a broken tape measure mess?

 

[DPittman]

I’m not sure how these springs work. Is the at rest position fully extended? What keeps the spring from turning into a broken tape measure mess?

Yes at rest they want to be fully extended but they have a tight recoil memory so they don't fully flatten out to "a broken tape measure mess".

 

[DavidR8]

How do they get mounted?

 

[Ironman]

Yes at rest they want to be fully extended but they have a tight recoil memory so they don't fully flatten out to "a broken tape measure mess".

How do they get mounted?

Fully extended they are a tube.
You mount them by figuring out how, as it is going to be different for each different machine. You nare a machinist, after all, and can adapt these to anything.
The basics of mounting are shown in my last post attachment.

 

[slow-poke]

Small End - 20mm - Extended Length 250mm - Compressed length 40mm - big end 28mm
When you order give yourself some extra, you can always zip cut it if it is too much but if you need 30 inches, make it 34 so you still have some slight tension at full travel.

I did the 'measure the ends' when I started to mount these. I threw out the first attempt, as I found the diameters are not constant and vary with use. Then I did some research and found out the best thing is to be loose, and allowing much more room than you think you should. Here is a sheet I downloaded that should help you out. The internal guide is way more important than a outer cup. And one end needs to be anchored to prevent the whole thing rotating in unison with the lead screw when the spring is extended a lot. Best material for the cup and pilot is nylon, or aluminum.

Thanks for posting the guide, very helpful.