Spindle / collet runout

MR-1
1

Hi There,
I spent several days adjusting the tram of the head, both in X and in Y. I used a 1.2.3 block, and measured against multiple sides to make sure that the block was really parallel. It was nothing like what the online calculator indicated. In fact, it needed shims on the bottom of the spindle housing, not the top!

I put a magnetic base on the dial indicator, and clamped it to the big block at the bottom of the spindle carriage. I adjusted the dial indicator to run against a 123 block that I bolted about in the center of the plate. Anyway, along the X axis, I get 0.000 of movement on the dial indicator when going up the 3" side of the 123 block, which is great!

Along the y axis, I got it down to about +/- .001 along the side of the block.

I thought, ok, now that that perpendicular to the bed, I can use my new EDGE tram gauge and it should read 0 if I rotate the spindle by hand.

So I chucked it up, and the gauges move a lot, like +/- 0 .010 as I rotate the spindle 180 degrees. If I set one gauge to read 0, with it facing the front of the machine, and then I rotate the spindle 180 degrees, it may read .010".

I could not figure where the error was coming from. I put a dial indicator on the outside of the spindle and rotated it by hand, and the indicator only moves +/- .0005 or so, so its pretty good.

I put a 1/2" collet in, and put in my ‘only’ 1/2" endmill, made sure it was deep enough, and then indicated on it. It wobbled .004" up by the spindle nut, which I think is way too much.

I then put in a 3/8" collet and a 3/8" endmill, and got basically the same thing.

Suggestions? Could I have a poorly machined spindle?

Tracy

2

Check the runout with an indicator against the taper in the spindle itself. That’ll tell you if it is a spindle or collet issue.

If you’ve never used ER collets before then make sure that you are properly loading the collet into the collet but too. They have to be snapped in before you put anything into the collet.

1 Like
3

Yea, Im new to all this. Do you snap the collet into the nut, or the spindle?

Tracy

4

Make sure you’ve wiped the inside of the spindle and the collet to remove any debris. Snap it into the nut. The face of the collet and face of the nut should be on one plane.

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5

Snap into nut before inserting tool, it wont snap in if you have tool in it.

Also the shim calculator is only to align the Z axis rails in the vertical position, Perpendicular to the base plate. You can have the z axis rails perfectly perpendicular to the baseplate but your edge tools indicators or similar still showing way off because the spindle isn’t aligned with the z axis. You gotta put shim behind the spindle motor within the carriage for front/back and then you can thread holes in the carriage to adjust left and right or loosen bolts and tap carefully to one side or the other.

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6

Thank you, somehow I missed the video showing that the collet snaps into the nut. Now that I followed the directions, the end mill runs basically with zero runout.

VGT hit it on the head, so to speak. After I shimmed the Z axis and found the error of my ways (thats almost a machinist joke!), I put the EDGE products dual tram gauge in the spindle, and was dismayed to find it was way off (+.010 on one side, -.010 on the other). I came to the conclusion the only possible explanation was that the actual Z axis of the spindle was not aligned with the Z slide.

Now I am going to shim the motor to align the actual spindle. Is there a video or writeup which talks more about tramming the machine?

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Thats for that, see my response below!

8

I would do more than wipe the inside.
This debris is what came from both ends of my unused spindle.

image
image1293×938 639 KB

Not 100% clean yet but discovered some curious threads inside using an endoscope, possibly 1/4-20.
20230706213749

At present, I don’t have a proper dial indicator for accurately checking the spindle inside runout. But I got .0007” RO on the OD measured between the threaded portion and the wrench notches. Plus the thread OD measured almost .012” smaller dia. than safety3rd’s spindle. 23.80mm vs 24.097mm.

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I think they may have i havent looked, but i thought someone said they did, Theres a couple posts outlining the added threads for left right but maybe someone will chime in. If you watch a bridge port tramming video and apply the concepts it will work. just gotta get decide how to do it with out a rotation nut/gear to help you along. Lots of hammer taps and shim placement and rechecks

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Also keep in mind that collet nut needs be tight to draw the tapper of the collet into the tapper of the spindle. It is difficult to get enough torque on the nut with the mild steel wrenches that come with the mill and basically impossible to get to the 59ftlbs recommended for ER20.

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