Help wanted solving a mill bed problem

Suzuki4evr

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I have a little problem wich I have to solve so I have to determine what causes the problem so I hope someone can help. Lately I discovered that when ever I want to mill something on my mill/drill to get two sides parallel to each other,something goes wrong and it ends up slightly taper(ish).
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I would mill one side flat,turn the stock around and put the flat side on the bottom and my head tells that if I run the mill over the other side,then the two sides SHOULD be the same, but they are not. I usually work metric,but I will give the sizes imperial so you don't have to do the convertions. The sides are off by about 0.013 inches over a distance of 4.724inches. It's not much it won't work for me. I doubt that there is something wrong on the vice,because it is brand new.

It is as if the bed runs down to one side. Could this be a gib problem or something bigger. I guess I can run a dial indicator down the length of the bed to check if the bed is worn down to one side . Any other ideas would be appreciated FIX the problem
 
Is it the bed or the bottom of the vise? I would check the vise first. Remove the vise and check the table. with an indicator while moving. Also, if you have a surface plate, check the vise. The problem may be the vise. Just because a vise is new doesn't mean it is perfect. The bottom may have been hit and raised some material causing the vice not to sit flat. Or maybe the vice is not flat to begin with. Check everything.
 
Sorry, I gave some bad info. Don't bother moving the table as the spindle to table distance will not move at the same spot the indicator is. Also tramming the table will not tell you if you your table ways are not parallel with the table top. If you are out of tram you will just get a concave surface not a taper from end to end. That is why I would check the vice on a surface plate first.
If the vise checks good then there is something off on the machine itself. It could possibly be the ways are not square with each other on the knee.
 
If you turned the work piece end for end then put your machined side down on the vise wouldn't that give you a parallelogram of sorts even if your machine is out of tram? The movable jaw on my vise moves upward when tightened so I have to tap the work piece down. I have had some luck using round stock between the moveable jaw and the work-piece. Also is the cutting tool secured really tight? I No solutions here just questions.
Have a good day
Ray
 
Some basic checks should tell you if your machine is straight and square.
Just about all vises will hold a work piece, some do it much better than others. The problems are that the vise may not be flat or square and that the work piece may move about when you tighten it.
Hold the work piece in the vise, insert 2 parallels under, lightly tighten vise then tap down the work piece with a copper/lead/whateveryouhave/ mallet until parallels are gripped, a piece of paper under the end of each parallel makes it easy to check. Fully tighten vise, recheck paper and start cutting. Turn work piece over, deburr, replace in vise as above and cut 2nd side.
Just slapping the part in the vise and tightening the handle probably won't give you the result you're looking for.
 
Your using an all angle vise there. It has to be trammed in, you can't rely on the vernier scale on the vise. They just get you close to square and parallel. And follow what the others have said on tramming the vise in.
 
Ken,
He is milling from the top. So it has to be a parallel to table problem. Also even if the head is not trammed to the table the sides should be parallel. Just side to side would be concave slightly. And then not real bad unless tram is way off. So either the part is not sitting flat in vise, vise bottom is not flat and parallel. Or table is actually moving in a downward slope. Which would indicate a machine problem in the ways.
 
Take a tall parallel and clamp it in the vise--tall enough to stand clear of the jaws when tightened.
Take a dial indicator and mount it in the spindle.
Take a reading of the parallel across its length on the top and on both sides. This should <ahem> indicate where the problem lies.
 
Take a tall parallel and clamp it in the vise--tall enough to stand above the jaws of the vise.
Take a dial indicator and mount it in the spindle.
Take a measurement of the parallel along the top and on both sides--this should <ahem> indicate where the problem lies.
 
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