Mill Not Cutting Level

ddickey

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H-M Supporter Gold Member
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Was making a part and had to mill to size. It was a 1.375 long .675 square part that I needed to mill down to .510 on one side. It was only rough cut on the ends so I didn't square it up. Finished my cut and the part was out of square .003". Since the part was ruined I decided to square all sides with no difference.

I then took some measurements on the vise. With the DTI attached to the spindle I ran across the stationary jaw, no movement. Then I put a parallel in the vise and ran the indicator along the top, still no movement. Then I went along the Y axis on each way of the vise. Still nothing. When I jumped over to the other way just next to the solid jaw I saw .0004" movement.

I then cut a small square piece and proceeded to square it up, this time with my Superfly instead of an endmill. I was curious if trailing edge on the Superfly would cut. As I went from left to right there was a lot of contact with the trailing edge, more than normal I would say. From right to left I didn't hear any contact. I just trammed my head a couple weeks ago but I guess it must of come out. I'm surprised though as my reading on the vise were all fine.

Any other thoughts on this?
 
My Index 645 mill does almost the same thing, about .0015 to .0020" on most pieces say 3" x 6" and various thicknesses.
I blame it on old age! The mill that is, oh, and probably me, too. I know my mill table has thickness issues of about .002" from end to end on a 9 x 48" mill table.
 
Out of tram will not show up by sweeping a surface with an indicator. The work moves under a motionless indicator when you sweep. Tramming shows tilt of the spindle axis relative to a perpendicular to the table, vise, or work surface by rotating the indicator relative to a stationary surface.
 
Ah yes. Okay that makes sense.
 
Out of tram will not show up by sweeping a surface with an indicator. The work moves under a motionless indicator when you sweep. Tramming shows tilt of the spindle axis relative to a perpendicular to the table, vise, or work surface by rotating the indicator relative to a stationary surface.

I learned that lesson the hard way when I was just starting out! Wish I would have been a member here then.
 
When clamping work in my 4" swivel vise the work lifts off the parallels. I have read many comments about this problem and I use an old screwdriver shank to combat this problem. The shank is about 5/16" in diameter by 6" long, it helps but am not sure if it is totally effective. I saw a blog? where the machinist said he pounded the work piece down to the vise ways. I shudder at that idea (pounding) but did use a piece of 3/4" shafting about 3" long to tap a work piece down ( couldn't find the screw driver) last week just to see how much force is required to get a work piece down on the vise, surprisingly not that much.
Have a good day
Ray
 
The bottom of my Enco vise wasn't flat. If I put parallels in it and a piece of stock on them I'd get a tapered cut from one end to the other. Since I'm not a machinist by trade it took me awhile to realize what was wrong. I found the problem by taking the vise apart and using a surface gauge and granite surface plate to check the height of the ways in the vise. A little grinding and scraping and it was close to parallel.
 
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It was pointed out to me by a member here that quite possibly and probably so was that the piece has some stress and moved on me. Considering the size of the piece and how much I needed to take off I think this is very likely the case.
 
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