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Bimba air cylinder modification

I bought a bunch of 1-1/2" bore x 3/4" stroke single-acting pull-off air cylinders to use for clamping fixtures. They are perfect with the spring force to hold the part but the air input is on the front end. The back cap can be drilled and tapped 1/8" NPT and a fitting installed. This will make them push-type. BUT...there is a vent hole in the stainless tube at the back of the cylinder that must be plugged. I'm thinking of a hose clamp and a piece of rubber unless there's a better way. If I could take the cylinder apart I could TIG the hole closed but these are sealed, throw-away cylinders cylinders. They ARE worth modifying because I bought them for $4 each and they retail for $60. I need 16 of them modified.

Reply to
Tom Gardner
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sell them on ebay and buy proper cylinders.

i
Reply to
Ignoramus31510

Hmmm, $64 verses $960. I'll use the hose clamps and innertube.

Reply to
Tom Gardner

These cylinders cost next to nothing on ebay.

i
Reply to
Ignoramus31510

If you can hold the piston and thus the seals away from the hole area I bet you can TIG them and dump them in cold water before too much heat gets neat the seals.

Reply to
Pete C.

The piston IS pushed away by the spring, these are pull-off cylinders so the spring naturally extends them. I might try the TIG, thanks!

Reply to
Tom Gardner

I couldn't find them in the right size or quantity.

Reply to
Tom Gardner

You may want to test 1 first to be sure the piston seal is bidirectional. Art

Reply to
Artemus

"Tom Gardner" fired this volley in news:DcudnULeZNCXx63TnZ2dnUVZ snipped-for-privacy@giganews.com:

Tig can concentrate its heat in a small area. Wrap the whole body of the cylinder in a wet cloth, or better, suspend it all but the end-cap in a vessel of water, then weld away.

LLoyd

Reply to
Lloyd E. Sponenburgh

Yes. Very sound idea, as they are usually not bidirectional. That would cost a penny or two more for the seal...

bill

Reply to
Bill Martin

Yes, they are standard bi-directional pistons. I installed a fitting on the back of one and used a hose clamp and a strip of sheet rubber. It works perfectly! I was hoping for a more elegant solution but I ain't too proud to use the hose clamp fix.

Reply to
Tom Gardner

How big is the hole? Could you thread it and use a plug? A photo would help.

Reply to
Michael A. Terrell

Probably a standard Bimba vent hole, about 3/32" and the wall is about

1/32"thick. I was thinking the same thing, a #8 with a dab of goo.
Reply to
Tom Gardner

It would make it easy to convert to another use, later on and wouldn't take long to do the whole batch.

Reply to
Michael A. Terrell

I bought ten on the first round because it was the sweet spot for shipping. I think I'll get away with eight because they are 1-1/2" bore with plenty of clamping power. There are four block holders on the machine and each holds two blocks with a cylinder for each block. The machine cycles from one side of each holder to the other and the finished block is released then the operator moves that block to the fill station holder from the drill station. With ten cylinders, I'll only have two spares and they might be impossible to get years from now so I will buy another ten for future use...they WILL fail at some time. I should buy even more for other projects but where do you stop?

Reply to
Tom Gardner

Will you need to duplicate that machine some day? I look at the ecpected life, and how long I intend to keep omething, VS. the current cost of spares.

Reply to
Michael A. Terrell

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