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Tips on using a vise, stock pushed up when tightening

Stefano Prato

Plastic
Joined
Apr 17, 2021
Greetings,

I'm new to machining and I would like to have tips on how to solve a problem that I encountered recently.

I bought some parallels for my cheap machinist vise and I noticed that when I tighten the vise the stock is never in contact with the parallels. I was aware of this problem so I bought a soft hammer but I was surprised to see that no matter what the stock will never be firmly touching the parallels. At the very best there will be a single contact poi on just one of the 2 parallels. I tried to machine as flat as possible the surface that will be in contact with the parallels but nothing changed. I checked the parallelism of the parallels and the vise bed relative to a granite surface plate that the vise was sitting on and everything was in tolerance. I also checked parallelism with the machine axis and still in tolerance. I think that the problem is on the jaws or in the moving part of the vise. I also noticed that the sliding unit can easily be tilted by hand with a bit of pressure.

I saw that high-end vises have pull down mechanism so I guess this is a common problem and that's why I thought that maybe there are tips and tricks someone more experienced can share. I also tried to keep the stock down by having the spindle nose touching it (I have a hobby machine with a cheap spindle, I would have never done this with a real machine)and had no success.

Thanks and sorry for my english.
 
Greetings,

I'm new to machining and I would like to have tips on how to solve a problem that I encountered recently.

I bought some parallels for my cheap machinist vise and I noticed that when I tighten the vise the stock is never in contact with the parallels. I was aware of this problem so I bought a soft hammer but I was surprised to see that no matter what the stock will never be firmly touching the parallels. At the very best there will be a single contact poi on just one of the 2 parallels. I tried to machine as flat as possible the surface that will be in contact with the parallels but nothing changed. I checked the parallelism of the parallels and the vise bed relative to a granite surface plate that the vise was sitting on and everything was in tolerance. I also checked parallelism with the machine axis and still in tolerance. I think that the problem is on the jaws or in the moving part of the vise. I also noticed that the sliding unit can easily be tilted by hand with a bit of pressure.

I saw that high-end vises have pull down mechanism so I guess this is a common problem and that's why I thought that maybe there are tips and tricks someone more experienced can share. I also tried to keep the stock down by having the spindle nose touching it (I have a hobby machine with a cheap spindle, I would have never done this with a real machine)and had no success.

Thanks and sorry for my english.

Your English if fine for a Calabrese.

:D

You need to safely dispose of the scrap metel pretending to be a vise and the scrap metal pretending to be a mill and either.. find something less disappointing and more interesting to do with your life,

or... book a train to the NORTH of Italy, Milano, Torino, most anywhere in Lombardia .. along the Arno.. "etc., etc.

Because.. some of the finest machine tools this world has ever seen, and some of the of the best toolholding - vises included - were invented and manufactured right there.

IN ITALY!!!

You can NOT take "free advice" off the internet, shout it into the non-existent "ear" of a lump of badly designed and executed low-grade metal that it is:

your ROYAL wish and COMMAND that;

-- said alleged-vise "become" a Gerardi

-- the Milling Machine Shaped Oject morph itself into a Rambaudi.

You shall have to be more clever and subtle that that!

You might try offering them chocolate and sexual favours?

It will not work. They are what they are.

But it will surely keep you out of more expensive debauchery.

You even get to keep your ass. Well unless the scrap metal takes you UP on the perversions, anyway.

Seriously.

All that "pretend" crap is going to do is ruin tools, damage metal, raise risk of injury, and waste hours of your life you can never recover. The only thing it can teach you is bad habits and how to waste time at a higher cost than watching pigeon-shit petrify.

Find something REAL, not props for a cinema production, even if it is worn-out and broken.

Because "real" can be repaired, and more than just the one time.

But fake can never be fixed.

We do not even TALK about it:

Machinery Discussion Guidelines
 
If the two sides of the part being clamped are not parallel you can experience the same condition. Try placing a piece of aluminum wire between the movable jaw and the work piece.
 
If the two sides of the part being clamped are not parallel you can experience the same condition. Try placing a piece of aluminum wire between the movable jaw and the work piece.

Which is only a good solution, if at least one of the vise jaws is perpendicular to the bed of the mill.

I'd suggest that the starting point is an honest assessment of the condition of the vise, and it's jaws.

Good tooling won't produce good work automatically, but bad tooling sure makes it a lot harder than it should be.
 
An alternative to aluminum wire is a strip of heavy leather. Always place the leather or alu wire on the moveable-jaw side. Like fciron sort of says in post #2, you need to partially tighten the vise before the hammer strike. A dead-blow hammer is best.
 
Depending on the construction of the vise, you may also be able to "tighten something up", or install some shims in a place where clearance is present and allowing the vise jaw to lift. This is a common issue with many inexpensive vises made for milling and drill press work.

As another tactic, if you have a piece of material that is "just" smaller than the workpiece, like .002-.003" smaller, use that as a spacer at the bottom of the jaws (at the vise bed), and then clamp on your workpiece. This may cause you to have much better clamping at the top of the jaws, although you may still have issues with jaw lift.

Look at the vise carefully and try understand how it works, and doesn't work, and see what you can do to adjust.
 
It crosses my mind that a wedge holddown between the workpiece and the moving jaw of the vise would be worth trying. The type of wedge holddown I'm thinking of is commercially made by Starrett, and quite pricey, but diy versions are simple to make.

In fact, a thin parallel or rigid steel rule makes a workable substitute, especially if the vise jaw has a small horizontal groove above its horizontal centerline across it's full width. The parallel needs to be angled down from the vise jaw groove to the workpiece so that 1) the lower edge of the parallel in the jaw groove is 2) ABOVE the upper edge of the parallel where it bears against the workpiece.
 
Yes, this is a common, well known problem with parts that are being held in milling vises. The first thing you need to do is understand just what is going on to produce this lift. I made this sketch some years ago to show what is actually happening.

attachment.php


Only the important parts of the vise are shown and I do not show the parallels that are almost always a part of this situation. The dark gray at the bottom represents the bed of the vise. The lighter gray block on the right is the fixed jaw and the one on the left is the movable jaw. The vise's screw is shown as a white rectangle on the left. And the white block between the jaws is the item being worked on: it is shown in an elevated position as the parallels would place it.

The top illustration shows the situation just before the vise screw starts to apply any pressure on the item being held. Notice that all the parts are square and parallel to each other.

But when the screw starts to apply pressure, as shown (somewhat exaggerated) in the bottom, things start to react to the uneven forces. The item being held stops the advance of the movable jaw at the top, but there is nothing at the bottom to match this. So the bottom of the movable jaw continues to move for whatever distance is allowed by the looseness of the fit of it to the vise bed. There must be some amount of play in that fit or the movable jaw would not be able to move.

The left, bottom corner of the movable jaw becomes a pivot point and the movable jaw rotates about it. This lifts the right, bottom corner of that jaw so it is now above the vise bed and at an angle to the vertical. This, in turn lifts the left edge of the item being held while the fixed jaw, which does not move, holds the right side of that item at it's original height. So the item being held is both lifted, more on the left or movable jaw side and tilted. This lifts it off the parallels.

It is important to notice that this effect mostly happens when a part is supported on parallels or some other means, ABOVE the level of the vise's screw. When a part goes below that level or when it rests on the bed of the vise, the effect is very minimal and normally no corrective action is needed.

What can be done about it?

There are high end milling vises that employ a system of splitting the force of the screw into a combination of vectors: toward the fixed jaw and DOWN, in roughly equal parts. This tends to limit the lifting action. Also, high end milling vises are built to tighter tolerances. However, neither of these features nor the two combined will completely eliminate it. So far, this is the best system available.

There is a style of vise that is called "screwless" or a "machinist's" vise. These vises are not actually without a screw: the screw is there but a lot less visible than the normal vise screw which is in a horizontal position. In a screwless or machinist's vise, the screw is INSIDE the movable jaw and at a 45 degree angle in a downward direction. So as the screw is turned it both moves the movable jaw toward the fixed jaw and pulls it down. These screws have a pivot at the bottom end, are somewhat loose in their hole in the movable jaw, and have a limited range of action. So there are a series of positions where the bottom end of the screw can be placed so that the vise has a longer range of opening. This style of vise is also ground on all six sides to provide precise alignment on a milling table or in the jaws of another vise. I have two vises of this style and they work well.

Some, less expensive vises use a separate guide in the form of a horizontal rod that is fixed on it's two ends and which passes through a close fitting hole in the movable jaw. This also helps to prevent the tilting but is not as effective as the force split of the high end vises.

Another method that many vises use is to make the movable jaw longer and to clamp it on bottom facing ways on the bottom of the vise bed. Again, this helps but is not as effective as the above features (at lease in my humble opinion).

Tricks:

One trick is to use a DEAD BLOW hammer to tap the piece down as the vise's screw is being tightened. This dead blow hammer should have a soft face so that it does not damage the part. This is perhaps the most often used trick.

Another trick that I have used is to place a second piece of stock below the one on the parallels. This second piece of stock is sized to hold the bottom of the jaws apart by the same amount that the desired part does at the top. If it is accurate enough in thickness, the parallels can sit on it. Also an adjustable parallel can be used between the two main parallels that sit on the vise bed.

BUT, one of the best "work-arounds" that I have seen was in an internet video. The rough stock was placed on parallels with only a small part of it's bottom being gripped. Most of it was sticking out, above the top of the jaws. Then ALL the operations could be performed on FIVE sides to square it up and create any holes or slots or interior openings in the final part. All of this work was done on the part of the stock that was ABOVE the vise jaw tops. And, with some care in the direction of the cuts, these five sides automatically come out as square to each other as your mill allows. Then, the almost complete part was taken off the parallels and inverted. It was set as low as possible in the vise jaws, preferable against the vise bed. And then the sixth side was cut down to below the area that was originally used for holding it on the parallels. Ta, DA! Of course, this only works on parts of certain sizes and there is some waste when that sixth side is milled down.

Once you know the problem, there are many ways to work around it.

PS: Do not allow thermite to discourage you. This forum is oriented to the professional machinists and they often have limited patience toward new-bees.

In line with that, you may want to join another, home/hobby oriented machinist BB. A good one is:

General -

The Home Shop Machinist & Machinist's Workshop Magazine's BBS


Many people here also visit there.
 
Yes, this is a common, well known problem with parts that are being held in milling vises. The first thing you need to do is understand just what is going on to produce this lift. I made this sketch some years ago to show what is actually happening.

attachment.php


Only the important parts of the vise are shown and I do not show the parallels that are almost always a part of this situation. The dark gray at the bottom represents the bed of the vise. The lighter gray block on the right is the fixed jaw and the one on the left is the movable jaw. The vise's screw is shown as a white rectangle on the left. And the white block between the jaws is the item being worked on: it is shown in an elevated position as the parallels would place it.

The top illustration shows the situation just before the vise screw starts to apply any pressure on the item being held. Notice that all the parts are square and parallel to each other.

But when the screw starts to apply pressure, as shown (somewhat exaggerated) in the bottom, things start to react to the uneven forces. The item being held stops the advance of the movable jaw at the top, but there is nothing at the bottom to match this. So the bottom of the movable jaw continues to move for whatever distance is allowed by the looseness of the fit of it to the vise bed. There must be some amount of play in that fit or the movable jaw would not be able to move.

The left, bottom corner of the movable jaw becomes a pivot point and the movable jaw rotates about it. This lifts the right, bottom corner of that jaw so it is now above the vise bed and at an angle to the vertical. This, in turn lifts the left edge of the item being held while the fixed jaw, which does not move, holds the right side of that item at it's original height. So the item being held is both lifted, more on the left or movable jaw side and tilted. This lifts it off the parallels.

It is important to notice that this effect mostly happens when a part is supported on parallels or some other means, ABOVE the level of the vise's screw. When a part goes below that level or when it rests on the bed of the vise, the effect is very minimal and normally no corrective action is needed.

What can be done about it?

There are high end milling vises that employ a system of splitting the force of the screw into a combination of vectors: toward the fixed jaw and DOWN, in roughly equal parts. This tends to limit the lifting action. Also, high end milling vises are built to tighter tolerances. However, neither of these features nor the two combined will completely eliminate it. So far, this is the best system available.

There is a style of vise that is called "screwless" or a "machinist's" vise. These vises are not actually without a screw: the screw is there but a lot less visible than the normal vise screw which is in a horizontal position. In a screwless or machinist's vise, the screw is INSIDE the movable jaw and at a 45 degree angle in a downward direction. So as the screw is turned it both moves the movable jaw toward the fixed jaw and pulls it down. These screws have a pivot at the bottom end, are somewhat loose in their hole in the movable jaw, and have a limited range of action. So there are a series of positions where the bottom end of the screw can be placed so that the vise has a longer range of opening. This style of vise is also ground on all six sides to provide precise alignment on a milling table or in the jaws of another vise. I have two vises of this style and they work well.

Some, less expensive vises use a separate guide in the form of a horizontal rod that is fixed on it's two ends and which passes through a close fitting hole in the movable jaw. This also helps to prevent the tilting but is not as effective as the force split of the high end vises.

Another method that many vises use is to make the movable jaw longer and to clamp it on bottom facing ways on the bottom of the vise bed. Again, this helps but is not as effective as the above features (at lease in my humble opinion).

Tricks:

One trick is to use a DEAD BLOW hammer to tap the piece down as the vise's screw is being tightened. This dead blow hammer should have a soft face so that it does not damage the part. This is perhaps the most often used trick.

Another trick that I have used is to place a second piece of stock below the one on the parallels. This second piece of stock is sized to hold the bottom of the jaws apart by the same amount that the desired part does at the top. If it is accurate enough in thickness, the parallels can sit on it. Also an adjustable parallel can be used between the two main parallels that sit on the vise bed.

BUT, one of the best "work-arounds" that I have seen was in an internet video. The rough stock was placed on parallels with only a small part of it's bottom being gripped. Most of it was sticking out, above the top of the jaws. Then ALL the operations could be performed on FIVE sides to square it up and create any holes or slots or interior openings in the final part. All of this work was done on the part of the stock that was ABOVE the vise jaw tops. And, with some care in the direction of the cuts, these five sides automatically come out as square to each other as your mill allows. Then, the almost complete part was taken off the parallels and inverted. It was set as low as possible in the vise jaws, preferable against the vise bed. And then the sixth side was cut down to below the area that was originally used for holding it on the parallels. Ta, DA! Of course, this only works on parts of certain sizes and there is some waste when that sixth side is milled down.

Once you know the problem, there are many ways to work around it.

PS: Do not allow thermite to discourage you. This forum is oriented to the professional machinists and they often have limited patience toward new-bees.

In line with that, you may want to join another, home/hobby oriented machinist BB. A good one is:

General -

The Home Shop Machinist & Machinist's Workshop Magazine's BBS


Many people here also visit there.

WTF???

We should get MOUTH BREATHING LESSONS from you, next?

You DO have that shit written DOWN somewhere.. with an "exaggerated" sketch, "made some years ago"..yah?

Or is some poor sod on a rota to remind you to get your head out of rectal defilade and INHALE once in a while?

Now... given the above post as the rationale..?

Annnnnnnd:

Machinery Discussion Guidelines

Just whose ass do we have to kiss to get YOU to kindly take your own advice?

And motor off down the road?

Or even just honor PM's site rules?

Or is making long, foolish "look how DEFIANT I am!" posts just too damned addictive a habit to break ....without Hollywood re-hab and gender re-assignment surgery?

And a HABIT it surely is !!!:

OT: Why Was the Korean Fusion Thread Closed?

OT: A Good Discussion of Vitamin D and COVED-19

OT: Irritating Row of Buttons on Title Page Here

Just WHICH PART of your OWN statement:

"This forum is oriented to the professional machinists "

Was it you so badly MISSED on Korean Fusion, Vitamins, or hobbyists who wish cheap shit could be BULLSHAT into becoming gold if only by the addition of extra helpings of exponential ignorance?

If not also nuclear fusion. Or maybe only Vitamin pills?

An "irritating row of buttons" we can just Freaking DEAL WITH!

WTF???

He is not the one as needs "discouraged!"

Because HE may still be able to LEARN! Has even started on that.

YOU ARE!!!

Because YOU .. WILL NOT !!! And may.. never.

Refusniks! God must have loved them, or she would not have set Al Gore to inventing the internet!
 
WTF???

We should get MOUTH BREATHING LESSONS from you, next?

You DO have that shit written DOWN somewhere.. with an "exaggerated" sketch, "made some years ago"..yah?

Or is some poor sod on a rota to remind you to get your head out of rectal defilade and INHALE once in a while?

Now... given the above post as the rationale..?

Annnnnnnd:

Machinery Discussion Guidelines

Just whose ass do we have to kiss to get YOU to kindly take your own advice?

And motor off down the road?

Or even just honor PM's site rules?

Or is making long, foolish "look how DEFIANT I am!" posts just too damned addictive a habit to break ....without Hollywood re-hab and gender re-assignment surgery?

And a HABIT it surely is !!!:

OT: Why Was the Korean Fusion Thread Closed?

OT: A Good Discussion of Vitamin D and COVED-19

OT: Irritating Row of Buttons on Title Page Here

Just WHICH PART of your OWN statement:

"This forum is oriented to the professional machinists "

Was it you so badly MISSED on Korean Fusion, Vitamins, or hobbyists who wish cheap shit could be BULLSHAT into becoming gold if only by the addition of extra helpings of exponential ignorance?

If not also nuclear fusion. Or maybe only Vitamin pills?

An "irritating row of buttons" we can just Freaking DEAL WITH!

WTF???

He is not the one as needs "discouraged!"

Because HE may still be able to LEARN! Has even started on that.

YOU ARE!!!

Because YOU .. WILL NOT !!! And may.. never.

Refusniks! God must have loved them, or she would not have set Al Gore to inventing the internet!

Gosh thermite, did you eat something disagreeable?
 
stefano, i see two possibilities to treat your (or any) vice:

1. determine by how much the jaws (yes, the fixed jaw also) tilt and machine/grind them to that angle. rememer the torque appied. this helps some.

2. machine/grind horizontal serrations into the jaws and use pieces of hacksaw blades to clamp the stock. the smoth side goes into the grove, the teeth grip the stock. they are at an angle of 20-30° and press the stock down. if your not carefull stuff will come flying.
 
stefano, i see two possibilities to treat your (or any) vice:

1. determine by how much the jaws (yes, the fixed jaw also) tilt and machine/grind them to that angle. rememer the torque appied. this helps some.

2. machine/grind horizontal serrations into the jaws and use pieces of hacksaw blades to clamp the stock. the smoth side goes into the grove, the teeth grip the stock. they are at an angle of 20-30° and press the stock down. if your not carefull stuff will come flying.

Waste of time to "machine" on scheisse.

You CAN TOO gold-plate a turd. Ask any plater.
But if a turd is what it was? A turd it will forever BE!

CUT.. a modest collection.. of ignorant extruded aluminium "Ell". of several different sizes. All to vise jaw width. Copper would be nicer. But find it CHEAPLY you will not.

PLACE... the handiest size out of the chipped cawfee cup nearby over the top edge of the moveable jaw. Ell hanging over. To bear against the work.

Tighten. Smack down. Use.

And go and get a DECENT "pull down built-in" VISE in the time you did NOT waste f*****g around!

The POS MIGHT find a new home over on the drillpress. Or even at the bench... where HAND tools live?

BFD

We have ALL had those El Cheapo's cross our path. Most of us still do have one or two around the shop.

They just are not ALL we have.

Nor allowed NEAR a mill. Least of all, a playtoy imitation of one.

Crap-ass machine tools need BETTER workholding than good machine tools.
Not WORSE!

Acquire a good vise first?

It will "inspire" the search for a better mill. Really. It will.

"Learning curve" thing. Even GOD didn't get to start at the END.
 
Greetings,

I'm new to machining and I would like to have tips on how to solve a problem that I encountered recently.

I bought some parallels for my cheap machinist vise and I noticed that when I tighten the vise the stock is never in contact with the parallels. I was aware of this problem so I bought a soft hammer but I was surprised to see that no matter what the stock will never be firmly touching the parallels. At the very best there will be a single contact poi on just one of the 2 parallels. I tried to machine as flat as possible the surface that will be in contact with the parallels but nothing changed. I checked the parallelism of the parallels and the vise bed relative to a granite surface plate that the vise was sitting on and everything was in tolerance. I also checked parallelism with the machine axis and still in tolerance. I think that the problem is on the jaws or in the moving part of the vise. I also noticed that the sliding unit can easily be tilted by hand with a bit of pressure.

I saw that high-end vises have pull down mechanism so I guess this is a common problem and that's why I thought that maybe there are tips and tricks someone more experienced can share. I also tried to keep the stock down by having the spindle nose touching it (I have a hobby machine with a cheap spindle, I would have never done this with a real machine)and had no success.

Thanks and sorry for my english.

It helps to be high in the vise to seat on parallels.
 
It helps to be high in the vise to seat on parallels.
Squareness gage Part 1 - YouTube

Get real.

Kurt AngLock? Name-brand Vertical Mill? Mill-hand was born at night, but it wasn't LAST night?

Helps to have something to WORK WITH too, yah?

Vise-shaped-object HE has would prolly flick the high-seated block clear into the next village first tool-flute made contact with the enemy.

If it even waited for spindle power-on!

:(
 
Have the workpiece higher in the vise gripping on a 1/4ins works fine.When your milling first face square you can have it deeper if you want.But faces 3/4 which are the finished sizes should be gripped higher in the vise.Doesnt matter if parallel moves but should be down on final 2faces.Surprised if your vise doesnt have adjustment to stop the floating near jaw lifting.Have a look at your manual.Often its 2 grub screws on side of vise they nip the dovetail up on the vise and will stop it lifting.Nip them up as you wind the near jaw in and out you may have them too loose.Could be loads things like has been said the squareness of rough stock could be a problem have had this and had to Mc face1 M/c face2 M/c face3(which is where the problem could be.so leave this +) M/c face4 and go back to face3 and finish it
 
Have the workpiece higher in the vise gripping on a 1/4ins works fine.

Not if the jaw has severe tilt it does not.

And we already KNOW it IS 'severe' because that is why he CAME here,

Drillpress? No problem. Same vise.

Work set LOW, below the axis of the actuating screw... and that POS vise earns a crust, year after year, no drama atall.

Couple of old "Palmgrens"... one fifty years in use, a Taiwanese tilter, but over to the Walker-Turner drillpress.

Alzmetall also has a non-pulldown vise. Massive bugger.

Tiny Electro-Mechano can get by with STICKY TAPE!

But a drillpress ... is not ... a ....mill.

Mill?

Gerardi Modulars. "Quad-I".

And a non-pulldown Voltas-made James Morton Multivise II weird-bugger that can even get a solid grip on a Penrose Tribar.

Horses for courses. Tooling for the tools.

Yah have to keep in mind where the poor lad is STARTING FROM.

He haveth not.. what WE.. take for granted..

Niente che valga la pena di avere è facile!
Ogni muro è una porta solo se puoi farlo.
Non ho esattamente tirato fuori quelle morse modulari di precisione Gerardi dal culo!
 
Looks like a bullshit button's got stuck again.

It pays well. VERY!

Piss-off one guy out of a thousand who will get TF off his one ASS and go beat your game? Humanity advances. 999 passengers drop a coin into his fare box and get to enjoy the ride.

Kiss a thousand asses?
Humanity degenerates. Everybody TRIES to collect. But NOBODY rides.

Darwinian thing.

I LIKE living in a world of better men than I.
Not worse.

Gives one hope for a healthier FUTURE! Happier, safer and more prosperous, even.

So I run what I f****g got.

All seven of 'em...

What are the five thinking styles? Understanding synthesists, idealists, pragmatists, analysts, and realists - Thriveworks

:D
 








 
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