OK, back on topic.
I have completed this modification, and got some amazing results! Test milling 6061 I worked incrementally up to a cut of 0.1" depth with the full width of a 7/16 end mill, and it milled smoothly and quietly, under power feed, in both directions. I probably could have gone deeper, but wanted to see steel. I used a scrap block of 1018. Understand I am accustomed to not exceeding 0.020" on steel due to the way the job would chatter and make the mill sound like something wanted to come apart. So, I started out at 0.020, with great results. Increased to 0.040, still cutting smoothly and quietly. Increased to 0.060, and still worked well. Keep in mind this was cut dry, in both directions across the piece (so half the time the force applied to the moveable jaw on my 4" screwless vise) using an X axis powerfeed like that sold by LMS or MicroMark.
As an "acid test" I added some Tricut fluid to the piece and dialed in a depth of 0.080". I used hand feed just in case I needed to back pedal quickly. The mill grumbled a little, but I did make the pass OK.
These results thrilled me!
I feel I have quadrupled the capability lf this little mill simply by doing this plate mod, and wish I had seen this back in 2004 when I got the mill.
I am considering also trying filling the bottom of the column, below my spring air cylinder mount, but having just trammed the mill to a variance of only 0.0005" on both X and Y axes, I am hesitant to pull the column off to make the requisite plug for the pivot bolt holes to prevent whatever fill material I would use from adhering to the bolt.
I found that the sequence of tightening the 23mm bolt and the 4 bolts on the lower bar is important. I had everything trammed within that half mil mentioned above, but decided to snug the big nut again. Bad idea. I lost the tram and had to begin again from loose. I should mention the device I made to help with tramming. It is essentially a miniature tie rod, screwed between the column and base casting on the left side. Makes fine adjustments on X axis tram very easy, and holds the column vertical when the nut is removed. Here's a picture of it.
https://www.dropbox.com/s/o6rqs1huir7rmg9/Mill%20Column%20Turnbuckle%2014_0226.pngSo I had to tighten the big nut as tight as I wanted it, BEFORE beginning tightening the bar at the bottom of the stiffener plate. My mill has the typical forward head droop, so I then worked with the outer bolts first, tightning them together and watching the dial indicator I had on the spindle, contacting a precision ground steel plate clamped to the table, to eliminate the droop. Lastly, snug the inner bar bolts against the casting to stabilize the outer bolts, and I was good to go.
THANK YOU for this modification!!!!
