Anyone else have Precision Machinist Jacks ?

[hammernanvil]

I bought 3 precision machinist jacks at auction, I thought they were unique since I had never seen any like this before.
They are all approx. 3" in dia., about 1.250 thick or so, and have about a 1.250 dia. piston and they all only lift approx. 3/16ths
of an inch.

The worst one has EH Ritchie on it. The spring hold downs were terribly made, the holes weren't drilled on center in the cap or piston, and the screws were too long and all mangled from things not being aligned.
I might be able to rework it and get it working. I think they all need stiffer springs.
2nd best has Jerry Hamblens name on it, I have my doubts as to whether or not this man made it since the area where his name is has been all scratched out and his name put over it.

The best is a no name piece. The fit and finish is excellent , and it works good. The difference in the workmanship on the nicest one is quite a bit better than the other two, it's a shame the guy didn't put his name on it.

[J Tiers]

I've never heard "precision" and "machinist jacks" combined before...... Especially when parts don't fit.......??

Springs, not sure about those, what is their function? Maybe a pic or two?

[hammernanvil]

I've never heard "precision" and "machinist jacks" combined before...... Especially when parts don't fit.......??

Springs, not sure about those, what is their function? Maybe a pic or two?

LOL. Yes I imagine they may have been a project for a couple guys or something ?? The one that has engine turning marks on it is the nice one.

[boslab]

I think I know what you mean, look like a little bottle Jack with a knurled nut, Tommy bar (lovely name who the hell was Tommy) holes at 6 positions with a spring plunger in the middle to keep it in place I think, although I can see the point if your using them on a vertical surface I suppose.
They were normaly exercises in technical school, bit of turning, knurling drilling etc, I had a set of jacks that were B&S I think, nicely made fine thread with a lock collar, very useful if you were drilling an overhanging shaft as there was a vee topped one.
If yours are so bad as to be out of line etc they sound like metalwork class projects as Jerry indicates, not production " little red box" aka starret or something.
We had lots of them in work up to 2' tall, but in fairness if the work was 30 tons somthing substantial was useful apart from big oak blocks (it is genuinely suprising to see how much a 12" x12"x2' oak block will hold, I have put 400 tons on 4 of them, amazing stuff oak.
Either way it gives you somthing to tinker with, can't be bad.
Mark

[hammernanvil]

Here's a few pics as requested.


The one at top center is the worst made, the piston is tight, a little too tight I believe. It's the cap that holds the springs in that is the biggest problem.

Lower left is ok just needs stiffer springs I believe.
Lower right is real nice and works good. I should probably take close up pics of the three so you can see the differences.

[boslab]

I gotta admit my ignorance, I have never seen a machinists Jack like that in my life, you got me puzzled.
What I thought you were on about
https://www.google.co.uk/search?q=ma...JTT2PeQExf-yM:
Mark

[hammernanvil]

I gotta admit my ignorance, I have never seen a machinists Jack like that in my life, you got me puzzled.
What I thought you were on about
https://www.google.co.uk/search?q=ma...JTT2PeQExf-yM:
Mark

It's a pretty simple design really. I have no idea how old they are, I plan to take one to work into the tool room to ask around.
It's really just a cylinder with a piston that has a tapered cut, with a relief in the very top corner. Then the thumb screw is similar to a
set screw on the end, "kind of tapered". Screw it in piston raises, screw it out drops back down due to the springs putting downward pressure on the tabs.

[Jaakko Fagerlund]

Looks like something that would be nice on a surface grinder.

[Abner]

I gotta admit my ignorance, I have never seen a machinists Jack like that in my life, you got me puzzled.
What I thought you were on about
https://www.google.co.uk/search?q=ma...JTT2PeQExf-yM:
Mark

x2-
I have a home made one that I use to support the end of long pieces held in the mill vise. Very useful I might add. I don't quite understand the use for the ones you have shown, or rather why so complicated for such a simple task or they used for something else entirely.

[754]

Sounds like maybe a trade school project.

[boslab]

When I saw the pics I thought I was looking at somthing off a tensile test rig, like Instronic or Amsler, like a load cell housing, I've looked in all the books I have and can't find reference to one?
Mark

[hammernanvil]

Machine repairman I bought my mill from said these jacks are used in Inspection, but he uses them for other things as well.

[vpt]

I was going to mention that it doesn't look like they would take much force from clamping. For inspection sounds like a perfect use for them though.

[Mcruff]

I have one of these at home in one of my tool boxes that belonged to my grandfather.
not sure when it comes as made, he retired in 1969 from Allison aircraft. It looks like that one without the turning on the surface.