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Tramming KBC mill question.

whydontu

I Tried, It Broke
Premium Member
Assuming that the nod is related to an error between #217 and the frame, I'd be taking off the head and looking at the bearing surfaces. The geometry of the distance between the quill and the bearing means it wouldn't take much to generate a 0.005" nod. Might be as simple as a bit of scarf or some paint.

Image 2-5-24 at 11.18 AM.jpg
 

JustaDB

Ultra Member
Assuming that the nod is related to an error between #217 and the frame, I'd be taking off the head and looking at the bearing surfaces. The geometry of the distance between the quill and the bearing means it wouldn't take much to generate a 0.005" nod. Might be as simple as a bit of scarf or some paint.
When I assembled the mill, I made sure the mating surfaces were very clean & had just a touch of oil applied. Not saying there's nothing there, just that I would be surprised. I was pretty careful.
 

YotaBota

Mike
Premium Member
There could also be a discrepancy between #217 and the milling head itself.

Shimming the base at the front may need you to shim the sides as well to keep the rear from binding as you tighten down. But as mentioned before, shimming will be good until you swing the head to a new position. I wonder if you got the right combination of shims and then run a bead of JB Weld around the between the shims it would give enough support.

I had the X trammed to about a thou as well but the Y I never even measured. For the jobs I was doing and the knowledge I had at the time it didn't matter, I'm not in India but it was close enough.
 

JustaDB

Ultra Member
Shimming the base at the front may need you to shim the sides as well to keep the rear from binding as you tighten down
Which is why I was thinking larger, crescent-shaped shaped shims.
For the jobs I was doing and the knowledge I had at the time it didn't matter, I'm not in India but it was close enough.

I honestly don't know how much this will affect anything I make at this point, either. I just figgered I'd check it seeing as I was already there.
 

CWret

Ultra Member
Premium Member
My mill is a RF45 clone (Modern Tool’s model MD45). The 5mil nod was removed using shims.
A pair of 0.002” shims were installed above the middle bolts, 0.003” below it, and a 0.005” at the bottom.
4BD3A973-F3DE-46B1-BCDA-320F469153BF.jpeg

Shim install:
The Z gib locks were snugged so that the head would move but it took a noticeable effort. This step was considered necessary since the mill has a counter balance weight (its upward force has a rotational component that worsens the nod). The 3 head bolts were loosened and down pressure was put onto the table using the Z feed so that the 0.005” bottom shim was a tight fit and held in place by friction. The Z gib locks were tightened a little more and the 0.005” shim could still be moved. The left and right (0.002” & 0.003”) shims were installed. They were moved up and down a bit until all 5 shims had the same resistance (to being moved). The head bolts were snugged and all 5 shims became tight together. Torqued the bolts and no more nod.

(Well it wasn’t really that simple - the process needed some back and forth between balancing left-right tilt and removing nod. Also 0.003”, 0.004”, and 0.006” shims were tried before switching to above set of shims. Plus, just for sh!ts and giggles, all of the above was repeated with the counter balance disconnected.)

The bottom shim looks like Aliva’s but with shortened legs
969553BF-41E2-4AC5-B594-45BC444F83A2.jpeg
 
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