- Joined
- Jul 25, 2007
- Messages
- 1,380
I've been in need of a fast, reliable, and portable press that I can use to straighten blades.
I bought a 2-ton arbor press this past week and I wasn't too impressed.
I like hydraulic presses, but I don't like how cumbersome it is to release the ram. Some of my blades get a kink during tempering, and it seems I have about 5-7 seconds to straighten them before they cool too much.
After a little research, theory suggested that I could modify a bottle jack to make it self-releasing after one handle stroke. Obviously the disadvantage is that you are limited to the travel obtained by one pump.
It does work; I just finished modifying and re-assembling my bottle jack. One advantage is that you can manually pull the piston out to any position, that position becomes the new "home" position.
The modification is simply: remove or disable the check-valve that prevents oil from exiting the piston (high-pressure side). Leave the other check-valve intact (it prevents oil from flowing into the reservoir, the low-pressure side). Both check valves on my jack were directly under the handle; I did not need to disassemble the piston cylinder. You do need to drain the oil first, and re-fill it last.
On my jack, the check valve was simply a ball held in place by a small swedge. I just smashed the ball past the swedge with a pin punch and a hammer.
I used these two sites as guides:
http://www.hyjacks.net/ani_extraction.htm
http://www.peachparts.com/Wikka/DieselInjectorTester
So building the press will be the same as any other DIY hydraulic press. When I pull the handle, the ram will extend; when I hold the handle still, the ram will stay put; when I release the handle, the ram will release. If I pulled the piston out to a new "home" position, I use the release valve to return it to zero.
It should be very fast and efficient.
I bought a 2-ton arbor press this past week and I wasn't too impressed.
I like hydraulic presses, but I don't like how cumbersome it is to release the ram. Some of my blades get a kink during tempering, and it seems I have about 5-7 seconds to straighten them before they cool too much.
After a little research, theory suggested that I could modify a bottle jack to make it self-releasing after one handle stroke. Obviously the disadvantage is that you are limited to the travel obtained by one pump.
It does work; I just finished modifying and re-assembling my bottle jack. One advantage is that you can manually pull the piston out to any position, that position becomes the new "home" position.
The modification is simply: remove or disable the check-valve that prevents oil from exiting the piston (high-pressure side). Leave the other check-valve intact (it prevents oil from flowing into the reservoir, the low-pressure side). Both check valves on my jack were directly under the handle; I did not need to disassemble the piston cylinder. You do need to drain the oil first, and re-fill it last.
On my jack, the check valve was simply a ball held in place by a small swedge. I just smashed the ball past the swedge with a pin punch and a hammer.
I used these two sites as guides:
http://www.hyjacks.net/ani_extraction.htm
http://www.peachparts.com/Wikka/DieselInjectorTester
So building the press will be the same as any other DIY hydraulic press. When I pull the handle, the ram will extend; when I hold the handle still, the ram will stay put; when I release the handle, the ram will release. If I pulled the piston out to a new "home" position, I use the release valve to return it to zero.
It should be very fast and efficient.