What is it?

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Joined
Jan 27, 2015
Messages
8
Reaction score
2
I was at an automotive swap meet and found a Machinist tool box with a number of tools in it. I was going through it picking out some that I wanted to buy. The owner said to me "Why not just buy the whole box?" and gave me a price that was too good to pass up. When I got home and started going through the box I found these that I do not know what they are. My first thought is machinist jack but there are no flats on the screw to adjust with and no lock nuts to hold the position. There are four of them and a set of similar smaller ones. Anyone have an idea?
Thanks in Advance,
Gary
PXL_20230926_130603638.jpg
PXL_20230926_130204898.jpg
PXL_20230926_130456178.jpg
PXL_20230926_125618578.jpg
PXL_20230926_130412308.jpg
PXL_20230926_125522891.jpg
PXL_20230926_130603638.jpgPXL_20230926_125522891.jpgPXL_20230926_130412308.jpgPXL_20230926_125618578.jpgPXL_20230926_130456178.jpgPXL_20230926_130204898.jpg
 
Great looking tools. The first thing I thought of when I saw some of the photos of it looking like a mechanics chess set. The grid mat under it was suggesting a chess board.
 
I was at an automotive swap meet and found a Machinist tool box with a number of tools in it. I was going through it picking out some that I wanted to buy. The owner said to me "Why not just buy the whole box?" and gave me a price that was too good to pass up. When I got home and started going through the box I found these that I do not know what they are. My first thought is machinist jack but there are no flats on the screw to adjust with and no lock nuts to hold the position. There are four of them and a set of similar smaller ones. Anyone have an idea?
Thanks in Advance,
Gary
View attachment 150213View attachment 150214View attachment 150215View attachment 150216View attachment 150217View attachment 150218View attachment 150213View attachment 150218View attachment 150217View attachment 150216View attachment 150215View attachment 150214
The small pointed ones look like something you would use to transfer hole marking to another piece.
Screw them to a stud that needs to be mated to another piece. Lay the piece that needs the holes on the pointed
tips and lightly tap on each one to make a mark. Then center punch the new marks and drill holes.
 
I agree with Steve Hucks. Since there are four in each size it might be they were set up to level or space some kind of jig for a specific job.

I also see how the pointed ones could be for transfer marking.

I could also see the rounded ones being used as part of some kind of measuring-tool extension. I envision a dial indicator with a loooong extension.

--ShopShoe

P.S.: Perhaps the rounded ones could be for setting up for transfer marking, but needing to center in a hole instead of on a punch mark.
 
I'm sure these are screw jacks. But not for machining directly, IMHO...
When setting-up against a dial gauge, in case there are any imperfect alignments between Milling head and travelling base, you can set a workpiece absolutely true if you jack until a flat surface gives zero deflection when travelling beneath the dial gauge. 4 jacks of the same size can be hand adjusted to height then when set the job can be clamped in place. - I guess?
BUT: Perhaps these are not intended as machining jacks, but used on the surface table with Height gauges, Slips, etc. as the hemispheres are not good surfaces for clamping against to resist machining loads?
Also, if you have a rough casting that has some spot faced holes as the only reasonable points for setting-up and marking, then these hemispherical jacks can reliably pick up on the holes for a repeatable set-up on the surface table. Is there a proper toolmaker who knows?
K2
 
The pointed ones made me think of the sort of thing that is often used in painting or staining wood - something to hold the part up, without significantly affecting the paint that is already on the side facing down. But since I don't see any paint on the items shown, I'm guessing that's not it.
 
Think screw jacks, the smaller ones a very similar to one of the apprenticeship training jobs we had to make when i started at Vickers Armstrong shipbuilders. a long long time ago
 
I have seen these before. Grandfather used them in different ways. Short ones used to set up sine bar. Thread was 64 tpi or so. Also used them for taper turning. Half ball instead of 60° point . He made them . added lock nuts .
 
I have seen these before. Grandfather used them in different ways. Short ones used to set up sine bar. Thread was 64 tpi or so. Also used them for taper turning. Half ball instead of 60° point . He made them . added lock nuts .
Good to know. There was another shop made fixture in the box that looked like it might be used with a sine bar.
Thanks
 
They look like shopmade machinist's screw jacks made using the domed tappet adjuster screws off the rocker arms of a large diesel engine, probably Cat. They would be high tensile, hardened and with a beautifully ground half-ball on the end.
 
I was at an automotive swap meet and found a Machinist tool box with a number of tools in it. I was going through it picking out some that I wanted to buy. The owner said to me "Why not just buy the whole box?" and gave me a price that was too good to pass up. When I got home and started going through the box I found these that I do not know what they are. My first thought is machinist jack but there are no flats on the screw to adjust with and no lock nuts to hold the position. There are four of them and a set of similar smaller ones. Anyone have an idea?
Thanks in Advance,
Gary
View attachment 150213View attachment 150214View attachment 150215View attachment 150216View attachment 150217View attachment 150218View attachment 150213View attachment 150218View attachment 150217View attachment 150216View attachment 150215View attachment 150214
Looks like home made jack stands
 
There not machinist jacks and there meant to be pre set with either a micrometer or a dti that's also been compared and zeroed for elevation to a stack of gauge blocks. The screw in the bottom would be used to lock whatever height they were set to. There used on a surface plate or CMM to support an object on 3 points. That way the top surface can be compared to the bottom for parallelism from all directions. Also handy when the part might have protrusions on both the top and bottom. My best guess is 4 of each were made for use with larger or unbalanced parts. For anything smaller and balanced, then the 3 point contact is stable and would prevent any minor rocking. For larger parts, then setting there support locations under the part much like the airy points used on a surface plate is also something else to consider.

They look like something a good toolmaker would make for himself unless you can find a manufacturer's name stamped somewhere on them. The ends should be very hard and precision ground and possibly lapped. I suspect the ball tips would be for unhardened part surfaces and those sharp tips for hardened. That's only a guess though. There a pretty limited and fairly specialized accessory tool and few with a home shop would ever need them for what there intended purpose was. If you did need actual machinist jacks, I'd just make my own with a proper and more accesable locking nut.
 
Thanks Pete. An excellent explanation! A nice tool if you have a quality surface plate and measuring station. My mate was from a tool room (then advanced to works Manager). and he does his measurements in a spare bedroom with a thermostat.., because he wants a clean room of fairly constant temperature. Away from his machining zone. Has a large thick wooden holder for his cast iron surface plate. And a set of slips and other gauges. (His retirement present!). He is happy when he clocks something to 0.0001" !!
He would love those jacks.
Except he is now blind, so cannot do any work any more...
Lesson: Enjoy what you can while you can!
K2.
 
There are screwdriver slots in the ends of those domed screws because they are valve adjuster screws out of a large diesel engine such as a Caterpillar. Common as anything. If you want to make your own jacks like that, you can buy the screws online easily enough. Google Caterpillar valve adjuster screws.
Here is one in its native habitat in a Cat rocker arm.
<a href=""><img src="



Whether you would actually use those slots to adjust the jacks seems rather unclear. Pretty fiddly to get under the base to get to them.
 
Last edited:
Back
Top