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Thread: spin indexer

  1. #1
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    Default spin indexer

    This thing has been sitting here for maybe a couple of years, when I got it I looked at it and thought that it was a POS so i never used it. I am hoping that i can get by using this for little jobs and get a bit more versatility between machines, my dividing head and rotary tables are a pain getting on and off machines.
    I have done a bit of work to this to hopefully stiffen it up a bit, the only other person in this forum to have a go at one of these (that i could find) is Anorak Bob, his fantastic work on one of these miniature boat anchors can be found here, https://metalworkforums.com/f65/t204...-modifications
    I thought i would try locking the spindle by pulling it back into a 30 deg taper, this should also give me repeatability/accuracy and removes end float. I turned a ring and lightly pressed it into the front of the body then set the body up in a 4 jaw in the lathe and cut the 30 deg taper, then cut the existing shoulder on the spindle to the same taper. I will lap the tapers together and likely re-grind the 5c taper, i will check this but i reckon it will be out.
    I moved the shaft inwards and this reduced the clearance between the indexing disc and the body to about 1mm, that should take a bit of load off the indexing pin.
    You would reckon there would be a shaft key? The only thing to stop the shaft spinning is the index pin that engages a hole in the index disc and a dodgy nut, no key, so it got one while i was at it.
    A new nut was needed so it was made to give a bit of rigidity to the end of the shaft that the collet pushes outwards against, the shaft does not have much meat there.
    The hand wheel thread at the back pulls the shaft into the taper and also pushes on the spacer that pushes on the body to tighten the spindle, I have left enough thickness on the rim of the hand wheel to drill holes should i need to get more purchase.
    The hand wheel is made out of 20mm ms plate and has 50mm dia 4140 pressed into the centre and welded, i used 50mm as i wanted to keep the weld away from where the thread was to be cut,
    The spacer was made out of an off cut of black pipe, i poured mig weld into each end to build it up then machined to size.
    I don't like hitting things to release tapers, particularly on the grinder as it can take quite a while setting up when chasing tenths and one little tap and you have lost it, so i made a new collet draw tube with a left hand thread and cut a matching left hand thread 60mm deep in the spindle, wind the handle clockwise to tighten, wind the handle anti clockwise to release the job in the collet.
    Then cut the the thread for the spindle lock in the first 20mm of the spindle.
    By doing the draw bar mod i can now only get 150mm deep into the spindle with stock larger than 22mm dia, so 22mm will go right through and up to 25mm will go in 150mm.
    You win some you lose some.
    I don't think i am going to modify the base to suit a particular machine as i think i can just clamp it down.

    cheers, shed
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  2. #2
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    Default

    Pete F also did one -
    https://metalworkforums.com/f65/t188...ling-spindexer

    Nice work though.

    Michael

  3. #3
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    Default

    That's a great series on improvements I really like the taper lock!!

  4. #4
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    Thanks Ralph, not only did I want to stop the shaft from moving or rotating I wanted to eliminate chatter, or at least reduce the chance of it as best as possible, clamping it at the front of the spindle should enhance surface finish and give more accurate finishing to the required size/dimensions, sharper cutting edges ect........

    cheers, shed

  5. #5
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    Thanks for the kind words John. You have applied your typical magic to acheive a worthwhile transformation.

    One thing, my understanding is that the indexing ring is rotatable (keyless) on the spindle to allow the spindle to be adjusted into position or fine tuned, independant of the indexing ring. These indexers were primarily intended for use with grinders. I modified mine to take advantage of its lower centre height, providing an alternative to my mill's Z consuming dividing head. There was no way that the spindle wouldn't rotate if the only means of securing the indexing ring to the spindle was the threaded collar hence the split cotter clamp.

    Bob.

  6. #6
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    Quote Originally Posted by Anorak Bob View Post
    Thanks for the kind words John. You have applied your typical magic to acheive a worthwhile transformation.
    Bob.
    Thanks Bob,

    Quote Originally Posted by Anorak Bob View Post
    One thing, my understanding is that the indexing ring is rotatable (keyless) on the spindle to allow the spindle to be adjusted into position or fine tuned, independant of the indexing ring.
    Often/sometimes an improvement to one function of a tool can be a detriment elsewhere, I weighed up the loss of being able to rotate the shaft in relation to the indexing ring and felt that for my use I would rather have it keyed to eliminate any chance of slippage.
    I think that mostly this tool will hold cylindrical parts and these can be rotated into position before tightening the collet, I have no intention of buying collets to hold square and hex. But I do have a need for holding hex bar and also maybe gripping cylinders from the inside so I have ordered a 80mm 3 jaw, it will be a smaller version of the chuck in the pic below, It will be held with a 28mm collet, this can be positioned to the indexing ring also, oh yeah...and make a better handle to get more torque on the draw tube.
    If the 3 jaw chuck is successful then I might also do a 4 jaw in the same manner.
    The 100mm 3 jaw in the pic is a bit big and not good enough to be worth the effort.

    My punch former has a v block so can hold odd shapes and it can be adjusted this way and that way, when on the t&cg it is quite versatile and accurate for short length jobs like cutting tools, it is pictured with with diamond dresser mounted for radiusing grinding wheels.

    cheers, shed
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  7. #7
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    Yes it is a swings and roundabouts thing. I'm sure there are numerous enhancements that can be made to these spin indexers*but with the cheap Chinese version you are starting with a sow's ear IMO.
    I did make one additional accessory for mine, a dovetail spigot that enables the indexer to be mounted on a number of the Hercus tool and cutter grinder attachments, allowing it to swivel.

    * Tom"Oxtool" Lipton has a number of YouTube videos showing the enhancement of the spin indexer's indexing capabilities.

    Bob.

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