First ensure the press apron is centered on the press frame at its highest position.
Center the 6” x 10” aluminum plate (min, 1/4" thick) on the press apron.
Drill through the apron and plate with a No. 21 drill and tap the aluminum plate for #10-32 Allen head machine screws.
Enlarge the apron hole with a No. 9 drill bit and mount the plate finger tight.
Drill two 1/4” holes in opposite corners in the base of the bottle jack.
Place the bottle jack on the plate and screw the ram its full length and then pump the jack until the ram is centered in the jack ring on the press frame.
Scribe the dowel pin hole locations onto the plate, then remove the bottle jack.
Remove the plate and drill two 0.23” holes. Press in 1/4” x 1” dowels and secure on the apron with the machine screws.
Slightly enlarge the 1/4" holes in the bottle jack for easy installation and removal on and off the plate.
For press pads, use 3.5” dia. x 2.375" long aluminum round stock. Measure the jack locating ring's O.D. on the frame (approx 2.375" dia). and milled it out 3/4” deep into the pad.
Note: The pad cavity has to be chamfered due to the spot-welding beads on the jack ring to the frame.
Drill and tap a locking setscrew hole in the pad and secure it to the jack ring. Use a #10-32 screw minimum..
For the ram pad, measure the ram diameter and mill as above.
Note. There is some sight play (slop) with the press apron, so when the press apron is raised or lowered on the frame, realign the press pads and add pressure to square, then shim the gaps between the frame and press apron. The cheap wood shims for door jams from Menards work fine and don't scratch the paint. You can see one of the shims in the photos.
The load cell is a 10-to-1 Force to PSI. So a 0-4000 psi gauge is full scale since 20 tons is 40,000 lbs of force.
For accuracy on the small stuff like 1 to 3lb rockets, use the 0--1000 psi gauge on the other side of a 4000 psi rated ball valve. To press 1 lb whistles at 8600 loading psi which equals 3800 lbs of force, the gauge will read 380 psi. Pressure x Area = Force
Gauges are Grade A +/- 1% glycerin filled.
If anyone is interested in this prototype load cell, I am thinking about marketing the cell itself. I have static tested it at 37,000 lbs (90 lbs inlet air pressure to the jack) for 100 hours. I also use it as often as I can for O-ring wear. If necessary, O-ring replacements will cost under 5 dollars. Test were made with a electronic calibrated (button type) load cell and digital readout..
email me if you are interested.
Modify an affordable press into a reliable, functional rocket/comet press. Personally I find the standard (top down) press configuration cumbersome to press rockets but necessary to press bearings, sleeves, etc. These simple modifications to the press do not change the integrity of the press and has the advantage of quickly converting back into its original configuration.
In addition, I use the 20 ton air/over hydraulic bottle jack and set an inline regulator/filter for just enough air pressure needed for the task.
Caution: Pad cavities' diameter and depth will vary from press to press. Measure your press to ensure proper fit.
