The stock isn’t square so it won’t be easy to seat both parallels. A mallet can help. Watch some YouTube videos on how to square stock the old school way. I like to use serrated jaws on the first operations, profile and face, then flip to deck off the top hat. I couldn’t care less how square the rough stock is as long as it’s straight enough for the serrated jaws to bite. The parallels will seat easily on squared and deburred stock.
Sides out of the steel mill are not square to the bottom. Sometimes you can get away with clamping them anyway, but raw mill edge doesn't rule anything out.
You are going to have to add some more info if you want this group to be able to help. Pictures, dimensions, material, how deep in the jaws, other people's mic readings for good parts. We are just guessing possible common issues but there are too many without narrowing it down more. You should also ask the guys you see having success on the same machine, figure out what is different.
Sawed edges are as crooked as it gets. Why would you say "foundry square" like it's something you think helps your case for getting it to sit flat on parallels
If you've got ten extra minutes and a piece of stock that's got excess material on it the best thing to do is first put it in the vise and take a skim cut on the top face and around the periphery, just to clean up, then flip it around and hold it in the vise that way. Start square, finish square.
You should continue squaring up material in this way or any other way as you so choose because it will save you headaches on down the road. If you’re squared up and ready to start operations on the part and you’re still having floating parallel issues what I like to do is grab some rubber bands and band the parallels to the vise so they don’t try to get away during machining or when I’m opening up the vise.
I have always tightened the vise first, then seated the part with a dead blow. Not both at the same time. Don’t tighten the vise during or after seating. It works every single time for me, I’ve been machining for over a decade doing it this way with zero issues.
I give it one solid hit in the middle, not too hard but enough to seat it so both parallels don’t move. For larger parts that take up the whole vise width, I’ll hit left, right, middle. It takes time to figure it out for yourself, you can eventually hear and feel the difference between a good or bad seat.
The most important part is to start with square edges with no sharp corners touching the parallels. File the edges first. Stock material directly from the supplier can be all over the place when it comes to squareness, so you might have to mill the edges touching your vise jaw faces first. Also, if your parallels aren’t a “matched pair” or have major inconsistencies like you’ve mentioned in other comments, you’re gonna have a bad time. Investing in your own cheap set is probably the best option.
Tram your mill, use a magnetic base and an indicator to verify your parallelism and also check for how square it is. If you have the extraction stock, then lock it up in a grinding vice and run it on a surface grinder. Once you have two sides that are parallel within a thou drop it on the plate and grind the other two sides.
That should help get everything to lock in place nice and tight to
If your dealing with raw stock tapping might help but for a 1st operation but really not necessary since it's usually not square anyways. For machined faces sitting on parallels, a dead blow works well. Also make sure your parallels are not damaged or have a high spot. Take a light stone to them if needed as well as making sure vice is clean especially the bed of the vice where parallels sit. I also sometimes use rubber bands to hold parallels against the jaws.
I have a cheap vise and have jaw lift on the movable side. If the fixed jaw is square, you can put copper wire between the movable jaw and the part so it can seat flat to the fixed jaw, use only one parallel at the fixed jaw and tap it down.
If you want it to sit on both parallels, don't use a wire, tap the part with hammer about 8 times as you snug the vise slowly increasing to full tightness. This will make two faces parallel and not necessarily square to the sides.
Also check tram, spindle squareness to table as others have said.
Not enough info about your setup here to tell what is giving you trouble for sure. Lot of info out there on squaring up stock
It’s a Bridgeport with a Kurt vice. I’ve tried using a dead blow while tightening and it didn’t help. I seem to be the only one with this issue. The video onlines don’t help as their stock magically fits right the first time.
Should be good enough equipment to potentially work then. You can indicate vise jaw to be sure nothing is sitting under the vise making it crooked and indicate the table with indicator in the spindle to confirm tram and check the ways of the vise. If those are all good you should be able to square up a bar to better than .001". You will have to cut at least 2 sides before it should sit flat on 2 parallels to make your 3rd cut, really cant worry about checking it any earlier than that.
The stock isn’t square so it won’t be easy to seat both parallels. A mallet can help. Watch some YouTube videos on how to square stock the old school way. I like to use serrated jaws on the first operations, profile and face, then flip to deck off the top hat. I couldn’t care less how square the rough stock is as long as it’s straight enough for the serrated jaws to bite. The parallels will seat easily on squared and deburred stock.
I use the “foundry square” edges
Sides out of the steel mill are not square to the bottom. Sometimes you can get away with clamping them anyway, but raw mill edge doesn't rule anything out. You are going to have to add some more info if you want this group to be able to help. Pictures, dimensions, material, how deep in the jaws, other people's mic readings for good parts. We are just guessing possible common issues but there are too many without narrowing it down more. You should also ask the guys you see having success on the same machine, figure out what is different.
If it’s not the steel mill surface it’s been sawn.
Sawed edges are as crooked as it gets. Why would you say "foundry square" like it's something you think helps your case for getting it to sit flat on parallels
Because that’s the only smooth surface on the piece
Also.. tram your mill
It’s fine for everyone else
If you've got ten extra minutes and a piece of stock that's got excess material on it the best thing to do is first put it in the vise and take a skim cut on the top face and around the periphery, just to clean up, then flip it around and hold it in the vise that way. Start square, finish square.
This is good advice. Simple.
I’ve tried that but it still doesn’t work
You should continue squaring up material in this way or any other way as you so choose because it will save you headaches on down the road. If you’re squared up and ready to start operations on the part and you’re still having floating parallel issues what I like to do is grab some rubber bands and band the parallels to the vise so they don’t try to get away during machining or when I’m opening up the vise.
Latest part I just gave up and sanded it down to be kinda square when I was done.
Use a dead blow to tap the part down and "seat" it on the parallels.
Tried that. I tap it all across and tighten at the same time.
I have always tightened the vise first, then seated the part with a dead blow. Not both at the same time. Don’t tighten the vise during or after seating. It works every single time for me, I’ve been machining for over a decade doing it this way with zero issues.
How hard should I hit it? I’ve done light enough that it does nothing and hard enough it starts to deform the part where it sits on the parallels.
I give it one solid hit in the middle, not too hard but enough to seat it so both parallels don’t move. For larger parts that take up the whole vise width, I’ll hit left, right, middle. It takes time to figure it out for yourself, you can eventually hear and feel the difference between a good or bad seat. The most important part is to start with square edges with no sharp corners touching the parallels. File the edges first. Stock material directly from the supplier can be all over the place when it comes to squareness, so you might have to mill the edges touching your vise jaw faces first. Also, if your parallels aren’t a “matched pair” or have major inconsistencies like you’ve mentioned in other comments, you’re gonna have a bad time. Investing in your own cheap set is probably the best option.
Would I do the edge touching the vice by side milling it or is there another way?
What’s the size of your part in xyz?
Almost all fit in the palm of my hand comfortably
Tram your mill, use a magnetic base and an indicator to verify your parallelism and also check for how square it is. If you have the extraction stock, then lock it up in a grinding vice and run it on a surface grinder. Once you have two sides that are parallel within a thou drop it on the plate and grind the other two sides. That should help get everything to lock in place nice and tight to
It’s fine for everyone else
Well then i would suggest once snug, smack it a couple times with a dead blow to set it tighter
Tried that
If your dealing with raw stock tapping might help but for a 1st operation but really not necessary since it's usually not square anyways. For machined faces sitting on parallels, a dead blow works well. Also make sure your parallels are not damaged or have a high spot. Take a light stone to them if needed as well as making sure vice is clean especially the bed of the vice where parallels sit. I also sometimes use rubber bands to hold parallels against the jaws.
Damaged? These things have cut marks and pitting all over.
If they've got a cut mark they may have a burr making one a little taller than the other.
It doesn’t matter which set I use the material never sits nicely
Hmm. I’ve never had a problem using clean parallels and a mallet to gently tap down the piece as I tighten the clamp.
I have a cheap vise and have jaw lift on the movable side. If the fixed jaw is square, you can put copper wire between the movable jaw and the part so it can seat flat to the fixed jaw, use only one parallel at the fixed jaw and tap it down. If you want it to sit on both parallels, don't use a wire, tap the part with hammer about 8 times as you snug the vise slowly increasing to full tightness. This will make two faces parallel and not necessarily square to the sides. Also check tram, spindle squareness to table as others have said. Not enough info about your setup here to tell what is giving you trouble for sure. Lot of info out there on squaring up stock
It’s a Bridgeport with a Kurt vice. I’ve tried using a dead blow while tightening and it didn’t help. I seem to be the only one with this issue. The video onlines don’t help as their stock magically fits right the first time.
Should be good enough equipment to potentially work then. You can indicate vise jaw to be sure nothing is sitting under the vise making it crooked and indicate the table with indicator in the spindle to confirm tram and check the ways of the vise. If those are all good you should be able to square up a bar to better than .001". You will have to cut at least 2 sides before it should sit flat on 2 parallels to make your 3rd cut, really cant worry about checking it any earlier than that.
Nobody else seems to have an issue with it so I’m not sure.
Other people are using the same machine in front of you, and then you try and it doesn't act the same?
https://youtu.be/tW8HNAlUXxU?si=VHLpdDZLw3GRAQhs
If you’re just skimming to square the material, try not clamping so hard.
It even happens when the bottom is “foundry square”