Wells Index 747 Keyway Missing?
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  1. #1
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    Default Wells Index 747 Keyway Missing?

    I bought a 747 mill late last year. It's been working like a charm for drilling and milling with my 1/2" mill and collet. I needed to mill a 1/4" slot in something over the weekend, so I pulled out my 1/4" collet and end mill to put in the machine. However, I was unable to tighten the collet down inside of the spindle. I thought this to be very weird, as the r8 taper for the drill chuck and my 1/2" collet worked with no problems at all. So I started inspecting and found that the spindle has no keyway for the collet to slide into. Is this common? Why does the 1/2" collect fit and able to fully tighten down, but the 1/4" collet doesn't go all the way in (about an 1/8" from going all the way up into the shaft) and it won't tighten down at all. The drawbar just keeps on spinning. I bought a collet kit, so they are all from the same maker. Any help will be greatly appreciated. And please pardon me if I am not very clear or say "the wrong things." I am not a machinist or anything like that. I am a hobby knifemaker who happens to own a mill, which I'm still learning about.

    Thanks,
    Seth

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    Put the two collets side by side. Examine the keyway cut into each of them. What is different? Does one taper out to the OD sooner? Better yet, take a picture of them side by side (with the keyways showing) and post it here, we'll help.

  3. #3
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    The keyway is only to help install and remove the collet. It is not intended to transfer torque under power. Many people remove the pin inside the quill so it does not damage a spun collet.
    Bil lD

    See link for milling machine training manual.
    US Army courses | Open Source Machine

  4. #4
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    Here is the two collets in question. The left is the 1/2” and the right is the 1/4”.
    433a4dc7-f9a6-4af5-b4d6-2824f0d6ec34.jpg
    Looks like the photo got uploaded sideways.. the bottom is the 1/2”.

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    Clearly the upper collet key way looks wider than the bottom collet key way. They also appear to be different designs as there is a collar of sorts below the taper on the top one. Measure them to see if there are other differences.

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    See how far the proper size screw screws into the back of each collet. I'll bet the 1/4" one drags or stalls short of going all the way in.

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    Try running a tap through the collet that "stops" before being tightened. It could be that the threads are just rough after a certain point.

    JMHO

    -Ron

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    I have run into a lot of the import collets where the last few threads are rough and had to run a tap thru to clean up.

    It's kinda like during heat treat they got rough or were never finished to began with.

    I have gotten in the habit of running a tap thru any new collets just to keep from being pissed if they don't tightened correctly.Also keeps from screwing up the draw bolt threads.


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