Noob question of the day: What's a machinist's jack for?

ValiantOne · Apr 9, 2009

Well, the title says it all.

What the heck is a machinists jack used for? Looks like a fun project but what do i DO with it!?

Thanks,

CE

mcruff · Apr 9, 2009

Leveling and supporting long parts in a vice. Supporting parts on angles and such. I use mine almost daily at work when machining long parts in the vise or disassembling stuff and you need to support something else. There are tons of uses for them.

10KPete · Apr 9, 2009

When setting up strange shapes on a mill, shaper, planer, drill press, etc., it's necessary to provide support and adjustment so the area to be machined is level or at the desired angle.

Jacks provide this support without having to mess with shims or wedges.

Pete

ScottieB · Apr 9, 2009

CE, do you have plans to make some?

ValiantOne · Apr 9, 2009

Thanks guys. That makes sense.

Scottie, i was just going to do something like this:

http://www.davehylands.com/Machinist/Projects/Machinist-Jack/

I've been trying to find a book with a bunch of beginner projects in it, but I've resorted to just finding things online

CE

mcruff · Apr 9, 2009

Those are nice enough. I would suggest one change though. Counter bore thebottom side so you can make extensions to add to them like the Starrets are made. If those are say 1 1/4" in diameter you basically bore the bottom out to 1" diameter by 1/8" deep and add that step to the top of the spacer when making them. You can make a few spacers about 3/4", 1" and 2" tall so you can add height to you screws when needed.

Good Luck!

Sean Myers · Apr 9, 2009

They are also a godsend in holding up motors that bolt to the inside of the trapezoidal bases of machines (such as delta did in the 70's) when replacing the motor. Whichever engineer designed them should be shot, hung and drawn and quartered- there is just not enough room in there to work.

Sean

Jim B. · Apr 9, 2009

Sean Myers said:
They are also a godsend in holding up motors that bolt to the inside of the trapezoidal bases of machines (such as delta did in the 70's) when replacing the motor. Whichever engineer designed them should be shot, hung and drawn and quartered- there is just not enough room in there to work.

Sean

Don't blame us engineers!

It was probably a marketing decision made by a program manager and an accountant, both of whom never ran a machine.

Jim B.

ScottieB · Apr 9, 2009

CE, thanks for the link. Interesting stuff. I am kinda like you. I want a few projects. One, because it is fun. And two, because it helps a new guy learn. If you find a good project book, keep me informed, please.
I just ordered a couple of MLA project tools. The tool post holder and ball turning attachment. I can't wait to get them.

Bssc · Apr 9, 2009

Pictures of standard off the shelf ones in use ? I have a set and for the life of me can not see the use for them . I under stand the concept but do not see a use for the ones i have.

adamsgt · Apr 9, 2009

I used them for support when I cut the flats on a half octogon half round tapered rifle barrel on a mill.

rapidtap · Apr 9, 2009

plastic/Jerry

I use my jack on the milling machine. If I have a long rod in a vise, the jack will suport the end and keep it level. I can't do with out it. Have a good day
Jerry

10KPete · Apr 9, 2009

Well, I'm digging around trying to find an illustration of how these jacks are used but not having much luck right now.

But here is the link to the Starrett site for their jacks which shows all the various end fittings and how the 'extensions' stack together:

http://catalog.starrett.com/catalog...blenum=1&groupname="Little+Giant"+Jack+Screws

You can see that there are points and 'edges' as well as swivel tops so the jack can be 'engaged' with various surfaces for firm support.

Pete

10KPete · Apr 10, 2009

Well, I found one. And not really what I was looking for either.

Man, you'd think that the 'art' of setting up stuff on mills and such had completely died out! I sure couldn't find much out there.

http://books.google.com/books?id=4C...X&oi=book_result&ct=result&resnum=6#PPA913,M1

Found another one:

http://books.google.com/books?id=4C...X&oi=book_result&ct=result&resnum=6#PPA929,M1

Pete

Don_Hartman · Apr 10, 2009

I have a handful of the Starrett models with the accessories. They are a must when working on castings and items when nothing is flat and you need support. If you are going to make them by all means use fine threads thought. The fine thread will increase strength and adds fine adjustment.

Any time I see one at a Flea market or for sale I’ll buy it. I just bought one here on PM a month ago by trading for a few old drills I had. The really nice thing on the Starrett models is the interchangeable swivel ends.

Don

Tank · Apr 10, 2009

Don_Hartman said:
The really nice thing on the Starrett models is the interchangeable swivel ends.

Don

Don, I don't know how a guy could get along with out them either, the only thing I don't like about the Starret jacks are the assinine thread they use in the jacks. I'm sure this is so people have to buy their parts but sometimes it would be nice to use their post in your tapped hole or your post in their body. I know it's not impossible to figure out their thread, I just haven't been that po'ed yet. I just know it's not common. Otherwise this is one of those tools you can't get by without.

Don_Hartman · Apr 10, 2009

I never have paid attention to the threads... It is very fine thought.
I guess I will have to check that out tommorrow.

From the Starrett Web Page

"No. 190 and No. 191 have 20-pitch screws, and for those who desire a finer adjustment, the No. F190 has a 40-pitch screw."

Will have to check the thread diameter.

Don

Bssc · Apr 10, 2009

I'll have to snap a picture of mine i am now not certain of what I have .

Kyle Smith · Apr 13, 2009

Maybe this will give you some ideas, I used 5/8"-18 bolts and nuts.

rfan8312 · Sep 12, 2018

My bosses has me using these often, solely to check for flatness, in the inspection area when a part still has raw stock on one side of it.

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