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  1. #16
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,541

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    In theory you could plunge hob, but the cutter would be quite complex to get the right shape. On the hob that I made, self feeding was easy - the cutter was just a worm with a slightly larger diameter, flutes were on the mill and relieving was done with an angle grinder.

    Michael

  2. #17
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
    Posts
    1,522

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    Okay, The DSG has metric changegears so ill start by making a hob, I guess i can just pre gash the teeth with a slitting saw or gear cutter. How deep did you make your gashes before starting the hobbing?

  3. #18
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,541

    Default

    Metric change gears are not going to work. A worm & wormgear set is done on circular pitch - that is, the PCD of the gear x Pi/n. The number is usually not a nice round one, hence the gears. To cut a double start M2 worm (or cutter) on my lathe I would need to dial up 3tpi and then run it through a 33/49 gear pair to get the right pitch.

    Michael

  4. #19
    Join Date
    Jul 2011
    Location
    Adelaide
    Posts
    837

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    There was an article about relieving hobs on the lathe with a tool on a sliding mechanism driven by a cam in Model Engineer's Workshop about the same time as they serialised a version of the Jacobs hobbing machine.

  5. #20
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
    Posts
    1,522

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    Okay so a bit of progress has been made, Im hoping to have it running next week. I have the new worm in the feed gearbox and the feed gearbox back in the base of the machine. I really regret cutting the wiring to the two speed feed motor as beeping it all out and labelling it took a bunch of time but thems the brakes. I wanted to use some quick disconnect MIL style plugs to rejoin it, and i bought one at significant expense from RS but the contacts were very small and i just couldnt get seven strands of 16g wire packed in there.

    IMG_20181219_124538.jpgIMG_20181219_152335.jpgIMG_20181227_160931.jpgIMG_20181227_183439.jpg

    I also made a sleeve to repair my other butchery cutting the y axis driveshaft and have replaced every bearing i could get to. There were just chips everywhere, even packed under the bottom of the knee somehow.

    Right when i was filling the gearbox I found why there was absolutely no oil in there when i pulled it out. The filler neck that pokes out the front has a drain and a fill plug, the fill plug it vented with a hole in the middle and they were swapped! I have no idea how it wasn't seen as the oil puddle would have been massive. (6 litres in this box and 26 in the main gearbox)

    IMG_20181227_153846.jpgIMG_20181227_153848.jpg

  6. #21
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
    Posts
    1,522

    Default

    A couple of weeks ago with the help of another forum member I dismantled the apron of the DSG and found why the half nuts wouldn't engage. The handle just would not budge.

    The two halves of the half nuts are die cast in some kind of aluminium alloy, thankfully stronger than Zamak but still not a great choice.

    Someone had just busted the bottom of one of the cam tracks straight off.

    I don't have a good before picture but in one where I'm milling it off you can see the big chunk broken off.

    I used a piece of cast iron, thanks again Kryn!
    It's held on by SHCS and some 3mm dowel pins. Hopefully it holds up. I plunged the boring head down multiple times to rough it it and then finished blending it with a file.

    If anyone gets this model of DSG I would reccomend inspecting these as the alloy had swollen and jammed in its ways, causing someone to bust it trying to engage them.

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