Hi all,


I have a x2 mini mill for a while now. I'll be using this thread to track my progress as I attempt to improve the rigidity of the column.

I've done a lot of reading on what other folks have done. This have given me a lot of ideas. One area that I like to add my contribution is to quantify via repeatable tests of my progress. I also hope to identify the source of the problem that is backed by test data.

I will be documenting my effort over multiple posts with photos. Each picture is full resolution. You can read my dial directly if you look at it in full resolution.

Also, WARNING, I had to modify the clamp I used to hold the weight in my test. Before my modification, the clamp will slip and drop the weight! 20 pound of dumbbell weight can definitely break bones! See the bottom of this post of the test setup.

Anyway, I look forward to hearing your idea and suggestions.


***

To start, I've measured the baseline flex in the machine. All future efforts will be compared with these:

Test load: 20lb
Torque arm (diagonal from dumbbell weight to column base joint): 2.5ft.

Front column flex: 0.004"

Attachment 249656



Left column flex: 0.0005"

I am really surprised that this is so good!! I've rechecked multiple times over multiple days this test.

Attachment 249658


Right column flex: 0.0035"

Attachment 249662

back column flex: 0.0035"
Attachment 249660




Conclusion:

Needless to say, considering the small 20lb load, the numbers are really disappointing. The one bright spot is the left side flex of 0.0005". I have not figure out why it is so much better. But it does suggest the whole thing can be improved a lot.


Test setup:

My test setup came from metabo in this post
Home Model Engine Machinist - View Single Post - Reducing Mini-Mill Column Flex (and Column Y-Axis Alignment)


This is a really elegant way to achieve repeatable tests! It is way better than pushing the column by hand! Furthermore, I don't have to pull/push the column while at the same time trying to work my camera! It is brilliant!

However, there is a real danger that the stock clamp (the type depicted in the photo) will slip when 20lb are put on one end. The stock "live jaw" will give out under high load. This has happened to me. I modified the clamp to handle much higher load by:

1. drilling a handful of of holes in the steel bar
2. drill a hole in the "live jaw"
3. used a thick pin (see picture) to prevent the live jaw from slipping. (a thinner pin can snap)

When in use, please make sure it is the thick pin that is taking the load and not the 2 small metal plates that came with the clamp.

Please see photo below for how my modification works.

Attachment 249664

Even with this modification, to be honest, I am still not 100%comfortable. Please be careful and consider other safe guards.