Difficulty Fly Cutting on a Benchtop Milling Machine

In the case of a z-axis cut on a benchtop mill, it sounds like the proper method is to:
(1) take up lash while raising the head, and
(2) lock the z-axis.

Question to ponder (only talking about milling machines here):
(1) If a shop uses only RH cutters, are they advised to take up backlash solely by clockwise rotation of a handwheel? In other words, “to feed against the force of the cutter”.
 
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When I went out to take pictures of the stand bolted to the floor, I can see that *there is play*. This is definitely an issue.

The stand does not rock back-and-forth or side-to-side, but it rocks a fair amount across one diagonal.

How would you guys fix this? The lazy way to fix it would be to just hammer in a shim.

I think that tar paper would take up the slack, but I still don’t love the idea of the stand only having 2 anchor bolts. 3 points are required to determine a plane!
 
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Just a few comments, Erik.
  • It might be a crappy fly cutter or it might be too big for your machine. Sherline makes a 1" diameter inserted carbide fly cutter that is superb; it might be more suitable for your mill. I can take a DOC 10 times the cut you tried to take in steel on my Sherline with this flycutter.
  • I agree with jwmelvin. Lower the cutter below your intended setting and then raise it up to the setting you need. This removes the backlash in the system.
  • I really don't think the bolts on the base are an issue. My Sherline mill attaches to a board that is not attached to anything; the mill just sits on a table and it works fine. My RF-31 sits on a sheet metal base that is on casters and it has zero issues taking some pretty good cuts. Bolting a mill to the ground is unnecessary in my experience.
  • You might want to explore why the two Z-axis bolts are coming loose. Something is not fitted well if the head is vibrating loose.
 
The carbide tool is probably taking a lot of force to push- can you try a very sharp HSS tool instead?
I agree the diameter might be too much for a small mill like that
 
markba633csi said:
The carbide tool is probably taking a lot of force to push- can you try a very sharp HSS tool instead?
I agree the diameter might be too much for a small mill like that
Click to expand...

I have a tool bit in that size, so I can try that.
 
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