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  1. #136
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    Sep 2012
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    North Yorkshire UK
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    Hi Bill,

    Thankyou for your very interesting post ! As you say a sneaky idea, certainly a new slant, to me anyway, on making a worm wheel. It gives me more confidence that I can make it work.

    Actually the picture raises a question, do I need to mill a groove in the rim of the disc ? Or will the tap simply cut deeper as I advance the cross slide on each pass. I had calculated that I would need to go approximately 3 mm deep to get a 40% of the tap diameter to get the maximum thread coverage.
    Best Regards:
    Baron J.

  2. #137
    Join Date
    Nov 2010
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    Gippsland Victoria
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    734

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    Quote Originally Posted by BaronJ View Post
    Hi Bill,

    Actually the picture raises a question, do I need to mill a groove in the rim of the disc ?
    Hey John,

    This chap didn't have a groove seems like he cut straight to calculated depth. He is only cutting brass probably a bit easier to cut than steel ? Several other videos on youtube, worth a google search and a browse.

    https://www.youtube.com/watch?v=ie7dNOLgno0

    Some test cuts on aluminium or delrin might be educational before trying the planned workpiece. Its been reported that this method can be a bit unreliable if you use a straight fluted tap.

    You would get some better understanding of making gears from Ivan Law's book which is very good, read about pitch circle diameter that might help a bit. Also Helicron website, and Michael G's recent posts. I've only made a few gears by single point cutting on my mill and don't know very much about it. The whole subject is very interesting.

    I once saw a description of a similar sneaky way of cutting a groove in a wheel, imagine the scheme shown in the photo, but with a vertical endmill instead of a tap, then you rotate the wheel blank and it cuts a relatively accurate circular groove - no need for a form tool on lathe or a ball ended milling cutter.

    Gotta admit making a tapped gear has been on my huge list of "one day try these" for ages now.

    Bill

  3. #138
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    Sep 2012
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    North Yorkshire UK
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    Many thanks Bill,

    I've watched that video before and its one of the reasons that prompted me to buy a new spiral flute tap.

    But yes you are right, it would be a good idea to try a plastic wheel for practice. Though my wheel is hard aluminium cut from plate.

    Watch this space, I'll be back with some more pictures
    Best Regards:
    Baron J.

  4. #139
    Join Date
    Sep 2012
    Location
    North Yorkshire UK
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    Thumbs up Making a screw !

    Hi Guys,

    Originally I was going to find a suitable 3/16" BSW screw and make a sleeve to fit into the bearings !

    Since I couldn't find a 3/16" BSW screw amongst the half dozen biscuit tins full of mixed nuts bolts and various other fasteners. I decided to make a start on turning and threading a 3/16" BSW screw to be used to secure the aluminium disc onto the top of the lathe cross slide fixture.

    After thinking about it, I thought that it was daft making two parts when I could combine them into a single item. It would not only be quicker, but I wouldn't have to find two pieces of suitable metal. I have plenty of 10 mm diameter steel bar right at hand.

    So I used some 10 mm diameter free machining steel rod to make the screw. I started by turning the first 20 mm down to 6 mm diameter to suit the bearings. I then turned down the end 10 mm to 3/16" (.1875") and single pointed the thread from the end to the shoulder formed by the 6 mm diameter section. After which I parted the screw off leaving a 3 mm thick head. I then used a hacksaw to put a screwdriver slot in and filed a slight dome on the head.

    16-01-2020-002.JPG 16-01-2020-001.JPG
    This is a picture of the finished screw and the screw fitted into the lathe fixture.

    16-01-2020-003.JPG 16-01-2020-004.JPG
    The bearings placed on the screw and screwed into the fixture. I need to make a 10 thou thick washer to go under the hub of the bearings, since the hub and the outer are exactly the same width.

    16-01-2020-006.JPG 16-01-2020-005.jpg
    This is the aluminium disc in place on the fixture. The last picture is looking down on the disc mounted on the fixture.

    Its surprising how much work goes into the making such a simple item as a shoulder screw !

    I hope to get around to cutting some teeth shortly.

    Thanks Guys.
    Best Regards:
    Baron J.

  5. #140
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
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    68
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    4,722

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    I've cut a similar thing on the end of some flat bar for a micro adjuster for a taper turning jig, that I think Bill? ended up with.
    Unfortunately I don't think I took any pics of how I did it, as I searched my pics folder to no avail.
    Have attached a pic below of it, if it helps.
    I tried to crop the rest out but couldn't do it, it's located on the bottom right hand side.
    Taper 2 jig.jpg
    HTH
    Kryn
    To grow old is mandatory, growing up is optional.

  6. #141
    Join Date
    Sep 2012
    Location
    North Yorkshire UK
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    Thumbs up Worm Wheel hobbed !

    Hi Guys,

    Kryn, I've seen that picture before ! Somewhere I have some notes about the article where that taper turning jig was posted. A very neat way of turning a Morse or other taper.

    Now on to my worm wheel. I've now cut the teeth into the aluminium disc. It took quite a few passes.

    17-01-2020-001.jpg 17-01-2020-002.JPG 17-01-2020-003.jpg
    These pictures are of the setup that I used. The new spiral flute M8 X 1.25 tap can be seen held in a collet and supported by the live centre in the tailstock. I ran the lathe at 120 rpm, so the actual cut wasn't overly fast. It took around 20 cuts, and I only managed two mm deep.

    17-01-2020-004.JPG 17-01-2020-005.JPG 17-01-2020-006.JPG
    This is the result. Not perfect but passable. If I was going to do this again I would mill a groove in the edge of the disc.

    Two things came to light here, the first was the bearings that were a tight finger press fit are now quite loose and fall out easily. The second was although I took great care to ensure that the horizontal centre line of the disc was absolutely spot on, the tap seemed to want to cut a little lower. If you look carefully at the pictures you can see a very small line along the teeth. I made a classic mistake of taking the disc off the jig to examine it and put it back on upside down compared to how it was originally. I'd taken several cuts before I realised what I had done.

    Still they are full form teeth and the screw fits almost perfectly. So at the moment I'm going to continue with using this worm wheel and see how it goes. I'll mill a groove in the next one. As far as the bearings being loose a spot of super glue should cure that.

    Thanks Guys.
    Best Regards:
    Baron J.

  7. #142
    Join Date
    Nov 2010
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    Gippsland Victoria
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    Quote Originally Posted by KBs PensNmore View Post
    I've cut a similar thing on the end of some flat bar for a micro adjuster for a taper turning jig, that I think Bill? ended up with.

    Taper 2 jig.jpg
    HTH
    Kryn
    Here are a couple of close ups of the thing Kryn is talking about at the bottom RH side of his photo.
    Attached Images Attached Images
    • File Type: jpg 1.jpg (126.1 KB, 10 views)
    • File Type: jpg 3.jpg (94.6 KB, 10 views)

  8. #143
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    May 2011
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    Murray Bridge S Aust.
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    Thanks for the how you did it. If it were to be done again, placing a large washer to take the load off the bearing/disc surface would probably keep it a finger press fit.
    Kryn
    To grow old is mandatory, growing up is optional.

  9. #144
    Join Date
    Sep 2012
    Location
    North Yorkshire UK
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    Hi Kryn, Guys,

    Thanks for your post.

    placing a large washer to take the load off the bearing/disc surface would probably keep it a finger press fit.
    I don't know if that would make a great deal of difference ! It would be worth trying through. The pressure is applied in a horizontal direction as the cross slide is wound in to apply the cut and the cutting action from the tap would be down pressing the disc against the fixture surface. I couldn't feel any rocking whilst hobbing.

    I must admit that I was surprised that the bearings became loose like they did. I tried to measure the amount that the hole holding the bearings had changed, but couldn't. The half thou gauge didn't show any movement side to side or rocking. That is a problem with a digital gauge, the last digit is either a zero or a five, nothing in between All I can say is the fit has gone from a good finger tight one to loose enough for the bearings to slide through.

    Anyway loctite 275 didn't secure the bearings, even left overnight, it might have been too cold or gone off but the loctite super glue locked them in place within a few seconds of application. I did notice that there was now a barely perceptible runout on the edge of the disc when spinning it.

    I now need to work out what I need to do to mount the piece of threaded rod that I am going to use for a worm to drive the wheel. I don't have a lot of room to mount the bearing blocks for it.
    Best Regards:
    Baron J.

  10. #145
    Join Date
    Aug 2011
    Location
    Melbourne
    Posts
    4,413

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    Hi Baron,

    None the less I like that worm wheel!

    Did you machine the concave in the disc before hobbing it?

    That may reduce the stress on the bearings by acting as a guide or groove for the tap to sit in.

    Simon

    Sent from my SM-G970F using Tapatalk
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  11. #146
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    Sep 2012
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    North Yorkshire UK
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    Hi Simon, Guys,

    Thanks for your likes.

    No Unfortunately ! It was one of those "shall I , shan’t I" things. In hindsight I wish that I had, it would have been much better. Annoyingly I have several ball ended milling cutters of 6.5 mm diameter and could have put one in the lathe collet and machined a groove easily. One of the things that you think about afterwards when I really should have thought about it first.

    My biggest surprise was the bearing loosening up ! Just shows how much metal will move under pressure, particularly something soft like aluminium.

    Anyway I think I've worked out how to mount the worm.
    Best Regards:
    Baron J.

  12. #147
    Join Date
    Sep 2012
    Location
    North Yorkshire UK
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    Thumbs up Worm Drawings.

    Hi Guys,

    I think that I have figured out a way to mount the worm so that it drives the wheel properly.

    Tool Holder support 3.png
    The parts in blue are brass pieces that are drilled to be able to mount them onto the back plate with M6 screws. They will have 5 mm drilled and reamed bores that will support the ends of the worm. One end will have an extended shaft for a knob in order to turn the worm.

    The drawing on the left shows the position of the brass pieces. The one on the right shows the detail.

    Thanks Guys.
    Best Regards:
    Baron J.

  13. #148
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    Nov 2017
    Location
    Geelong, Australia
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    54
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    1,207

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    That looks like it will do the job nicely, assuming you don't need to be able to disengage the worm. If you do, then allowing the far end block to pivot and the closer end to move laterally a few mm in a short slot would likely be enough to achieve that.

    A slight variation on your design would be to create the bearing blocks with a small spigot that goes down into a hole in the plate (instead of coming out the side like you've currently got it).
    To secure them, tap the spigot and use a screw from underneath the plate. Same functionality as what you have drawn, just uses less horizontal real estate.

    Steve

  14. #149
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    Sep 2012
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    Hi Steve,

    Thankyou for your suggestions.

    Unfortunately I created that problem by using a rounded top on the mounting plate ! I only allowed 10 mm distance above the aluminium disc and discovered that I didn't have enough room to support the worm. Hence the brackets supporting it have to be nearly 20 mm long just to stay within the mounting plate radius.

    The mounting hole and the bearing bore in the brackets are at 90 degrees to each other and do not need to be removed. As long as the worm screw is securely engaged in the teeth in the disc it should be fine.

    I'll post a picture later.
    Best Regards:
    Baron J.

  15. #150
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    Sep 2012
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    North Yorkshire UK
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    Thumbs up A picture !

    Hi Steve, Guys,

    The problem with drawings is I know what I mean These pictures should help clarify things.

    23-01-2020-001.jpg 23-01-2020-002.jpg
    These pictures show what I'm trying to do. The brass block is drilled 5.9 mm and reamed 5 mm to suit the spigot on the worm. I've not finished machining it yet the other end is still to be done. I intend to drill and thread M6 for the CSK fastening screws that will come up through the 8 mm thick stainless steel plate.

    I propose to finish both brass blocks and then machine the screw to suit the gap between the blocks when they are both fastened down. The second picture illustrates how the worm will look when finished. The shoulder screw in the centre of the wheel is threaded M6 for a nut and washer at the other side. I've yet to cut a screw driver slot in the top. That head is 2 mm thick and will be under the tool holder.

    Thanks for looking Guys.
    Best Regards:
    Baron J.

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