Spindle collet grub screw

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RSG
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Spindle collet grub screw

Post by RSG »

I finally got around to tramming my new mill and when I went to put a collet in it wouldn't go. Upon inspection with a lighted mirror I could see the grub screw sticks out too much. So I went online to see how to fix it and it appears fairly simple but I have one question.

Does the spindle collet ring have to be tightened to a torque spec or do I just follow what the fellow on YouTube said about tightening it back up? I was going to mark the ring before taking it off so I know how much to tighten it when it goes back on.

Any advice would be appreciated.
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John Evans
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Re: Spindle collet grub screw

Post by John Evans »

Normal procedure is to mark the ring and return to that position when dealing with the grub screw. Lots of the Pro guys remove it entirely .
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Harold_V
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Re: Spindle collet grub screw

Post by Harold_V »

John Evans wrote: Sat Sep 22, 2018 1:37 pm Lots of the Pro guys remove it entirely .
Something to mull.
I've never removed mine, and have no regrets, but there is an upside to removal. I've owned my mill since 1977, at which time it was purchased new. I am the only person who operates the machine, so I know what it's been through. That said, if an indicator is operated against the angle upon which the collet closes, there's a distinct pattern worn there. I'm not suggesting that concentricity is lost, as I don't recall the reading. By removing the pin, collets will seat randomly, creating a uniform wear pattern.

I am not recommending either position.

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RSG
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Re: Spindle collet grub screw

Post by RSG »

Thanks John!

Harold, interesting.....That's very insightful. I have noticed distinct wear lines on my collets from use in the old mill and those same lines translate to the inside of the spindle too. I think I might remove it all together as I've not noticed any particular reason for it as I've never felt any tooling spin in the collet.

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Richard_W
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Re: Spindle collet grub screw

Post by Richard_W »

The pin/screw to is not meant to be a driver of the collet. But is there in case the threads are tight to keep the collet from spinning while removing the collet. This rarely happens and then you would need a collet wrench if the screw/pin is missing. I have only had this happen once that I can recall in about 47 years of machine work. Most remove the pin on new machines or if the are by chance sheared off then not replaced.
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Harold_V
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Re: Spindle collet grub screw

Post by Harold_V »

What Richard said.

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Re: Spindle collet grub screw

Post by RSG »

Thanks Richard, good to know.
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Patio
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Re: Spindle collet grub screw

Post by Patio »

My mill came with the pin installed. The only time I found it useful, was when installing the right angle head.
I may remove mine, so that the spindle has a chance to wear more evenly. It is easy enough to get in and out, that it would not add much time to the set up, on the rare occasions that I do install the right angle head.
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BadDog
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Re: Spindle collet grub screw

Post by BadDog »

I didn't see it mentioned, but it is also useful if you have a power draw bar. Mine was troublesome on some collets, so I removed it.
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Re: Spindle collet grub screw

Post by RSG »

Thanks for the input guys
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pete
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Re: Spindle collet grub screw

Post by pete »

The only real use I've found for that set screw is it indexes anything put into the spindle taper to the same place each time. My 3D Haimer edge finder uses a dedicated 3/4" end mill holder and the edge finders C/L gets indicated in and adjusted until it's dead on to the spindles C/L. So it's helpful to have that same index position when it's being used. However I'd have to judge Forrest Addy as being extremely knowledgable and more than a little experienced so I pay close attention to anything he's got to say. He maintains it's possible at some point that set screw end could get sheared off. Forgetting just once to fully tighten the drawbar might be enough to do so if the cutting tool starts taking a large depth of cut with a semi loose drawbar. Not always, but sometimes that sheared off set scew tip can then jam between the R8 tool shank and the spindles taper. He's seen spindle tapers torn up and large problems even getting the tool shank out of the spindle.

That's good enough reasoning for me to remove it. Spot marking the spindle O.D. and the Haimers end mill holder with a small stone in a Dremel will still allow the same indexing for me.

Off topic for this thread, but maybe worth pointing out RSG. Forrest has also pointed out that breaking a knee gib is really really bad news. Some knees then get locked to the column so bad it's almost impossible to remove the pieces if someone trys forcing the knee to move with the crank. On any new mill that uses tapered gibs I think it's a good idea to pull each one and closely inspect it for any possible cracks or even a slightly bent condition. After reading some of the horror storys about a few experiencing that broken gib problem on the PM forums I'm now ultra paranoid about that ever happening. I doubt a steel one would get broken, but many mills use cast iron for the gib and they might not be that hard to break due to flexing over time if there not 100% flat.
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Harold_V
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Re: Spindle collet grub screw

Post by Harold_V »

Of note---an edge finder (mechanical type) doesn't benefit by being adjusted to run true, although it certainly does no harm to have it run in that condition. The degree of precision doesn't rely on the shank, which can oscillate and still yield the desired results. Same goes for a wiggler.

The set screw register in an R8 spindle.
If it is to remain, it should be prominent. If it is too short, it's possible to insert a collet without the register in the slot. If tightened, damage will likely result.

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