Gave it a quick test and this is what it does to a gutter nut, while under compression I put a straight edge across the top plate and deflection was less than 0.5 mm, so well happy with that, Rick
As it proved a right pain to push the piston back down I have added a pair of springs and by heck are they strong but do the job well almost still have to help the last 20 mm, after pumping it up to full height the 10 mm plate has deformed as can be seen in the pic with the straight edge on the top
But it does the job, finally got the shaft out of the trunion but it was on its limit and each pump produced a loud cracking noise that almost warranted ear defenders, Rick