Machinist Jacks

Discussion on all milling machines vertical & horizontal, including but not limited to Bridgeports, Hardinge, South Bend, Clausing, Van Norman, including imports.

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germaneighter
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Location: Owasso, OK

Machinist Jacks

Post by germaneighter » Fri May 03, 2019 3:49 pm

I've seen quite a few videos on "making" these jacks but I have not seen much at all on their use. Anyone have a pic or a video they could point me to?

thanks

pete
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Re: Machinist Jacks

Post by pete » Fri May 03, 2019 4:13 pm

No real need for a picture or video. On a machine tool like a mill there simply an adjustable height support point. Generally used along with step blocks, straps and the usual studs and tee nuts in a clamping kit to lock the work down onto that support at it's preset height. They help to support work outside the vise or with multiples even without using the vise at all for tool clearance above the table. One side benefit is using them can help to reduce chatter on long work outside the vise jaws. A stack of scrap cut offs if there the exact correct height or even a set of adjustable parallels can pretty much do about the same thing. It depends on your usual work piece size and shape if you'd even use them. One or two having a vee cut in the top surface of the machinist's jack is handy for longer shaft work as well. For long enough or smaller diameter shafts where part deflection under the cutting forces can happen, adding one or more between a dividing head and the foot stock is a big help to add rigidity to the part.

johnfreese
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Re: Machinist Jacks

Post by johnfreese » Fri May 03, 2019 4:58 pm

Watch enough You Tube videos on machining. You will see machinist jacks in use. Start with Stefan Gotteswinter.

germaneighter
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Re: Machinist Jacks

Post by germaneighter » Fri May 03, 2019 5:15 pm

Thanks pete and johnfreese !

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tornitore45
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Re: Machinist Jacks

Post by tornitore45 » Sat May 04, 2019 7:59 am

No need to buy any. An assortment of Tee Nuts, Short Studs, regular nuts, coupling nuts and bolts will always get you in the right position at the desired height.
Mauro Gaetano
in Austin TX

whateg0
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Re: Machinist Jacks

Post by whateg0 » Sun May 05, 2019 12:33 am

Many uses, from supporting the end of a workpiece, to actually jacking up stuff that a normal floor jack can't get under. Here's a pic I took of a recent project where I used a jack to keep the sides of the channel tight against the vise jaws to keep it from singing.
machinist jack.jpg
Dave

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tornitore45
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Re: Machinist Jacks

Post by tornitore45 » Sun May 05, 2019 5:49 am

When clamping a piece on the end of the vice, place the jack on the other side to eliminate the twisting load.
Mauro Gaetano
in Austin TX

germaneighter
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Location: Owasso, OK

Re: Machinist Jacks

Post by germaneighter » Mon May 06, 2019 10:23 am

Mauro & Dave - thanks for those examples

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BadDog
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Re: Machinist Jacks

Post by BadDog » Mon May 06, 2019 10:33 am

I've used them when clamping a too-short weldment in the pivoting bandsaw vise as described above. I also used one a couple weeks ago to support an awkward bend tube with hang-over flange on the surface grinder to keep it from pushing down from the wheel.
Russ
Master Floor Sweeper

johnfreese
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Re: Machinist Jacks

Post by johnfreese » Mon May 06, 2019 4:50 pm

The biggest use of jacks was on planers. They were used to position parts. usually castings, to get the top surface level. They were also used under clamps where the part did not touch the table. They prevented distortion when the clamp was tightened. Any of the old time machining textbooks show the setups. They are used a lot on horizontal boring machines, especially for the initial setup of castings or weldments.

Glenn Brooks
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Re: Machinist Jacks

Post by Glenn Brooks » Sat May 11, 2019 11:19 pm

Lots of good comments here. Over the years I’ve picked up three or four jacks, usually at estate sales when the price was ridiculously low. I do use them. Like many hobby machinists I only have one vise on my Mill. So the Jack is invaluable when supporting the end of a long piece of work- with the other end held in the vise.

If you have two matching vise - vices - you won’t need the jacks. But I don’t and I do (need them)...

Cheers,
Glenn
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

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whateg0
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Re: Machinist Jacks

Post by whateg0 » Mon May 13, 2019 11:02 am

I would like to add that if you have the option of having good machinist jacks or bad ones, go for the good! Crazy thought, huh?

I picked up the Starrett screw portion for each of mine off of Ebay for not much money and made the nut/base for them. They are smooth and the saddle swivels easily.

I also have a set of 4 that I picked up at an estate sale for a few bucks thinking, you never know when you'll need one more. Those things suck! They screw does not screw in or out smoothly. If under a load at all, they don't want to turn, so the whole thing, including the saddle wants to rotate under the part (if holding something up) or it wants to work its way out of the spot (if used as a spreader), as a couple of examples. I've never taken the time to try to clean up the threads, so maybe there's room for improvement there. But the saddle doesn't move easily or smoothly either, so I kind of feel like messing with the threads would be wasted effort.

FWIW, the cheap ones I have look like this, with no branding of any kind to be found.
Image

Dave

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