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frank

Posts: 46
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I want to make a top E-wheel adjuster and was looking at the acme threaded rod at the McMaster-Carr site. I got confused by all the choices. What is the best rod to use, one inch,ten threads/inch,type of material? Are there standard tubing sizes for the inner and outer parts of the adjuster when using plastic strips between the tubes?Thanks eh?
Frank

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bugger

Posts: 11
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I actually used the screw from a house jack that I had lying around and am very happy with the results, only complaint is that the finer threads take longer to move but allow for finer adjustment. thread count basically will only effect the rate of adjustment, diameter is what matters. I would go with the 1"

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66tiger

Posts: 84
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I designed an adjuster that uses a 1"-10 acme threaded rod, and I think I'd avoid it next time. The acme threads are tempting because, in theory, the threads are cut more accurately and so repeatability should be better, and the threads are much stronger than a normal coarse thread. The down side is that taps and dies for cutting them are very expensive, and the loads on the threads probably aren't high enough to even need the extra load capacity of the acme threads.

-- Arden

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frank

Posts: 46
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Arden,
Could you explain how you fixed the acme screw to the top of your adjuster.I really like your album,but don't see anything in your illustrations that show this. Thanks.
Frank

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stutz31

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I'm using 1 1/4" x 12 B7 rod from Mc Masters. They have the nuts to go along with it. I'll let you know how it works. Should have it up and running in 3 or 4 weeks.
Dick

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gapingghyll

Posts: 24
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Frank,

I used a piece of 1" x 10TPI threaded rod from the local industrial supply. I turned down both ends to form an upper bearing surface and a lower spigot. The spigot acts as a pilot for a thrust bearing which rides on the spigot shoulder and in a pocket in the attachment plate for the yoke. There is an upper boss with an oilite bushing to guide the screw vertically. The result was a very smooth action.

There is a second plate which acts as a support for the shoulder bolts (AKA - die stripper bolts) which also ride in bronze guides and are tensioned with die springs. The yoke is not cut in these shots.

I didn't think quite far enough ahead when I designed it. There was just a tad too much play for my liking - because the stripper bolt bushings were too short. I'm in the process of adding "towers" to take longer bushings. I'll use shorter springs since the long ones are not really needed - the original bolts and springs were just on hand.


HTH,
Graham



Attached Files:

  • Pocket.jpg (34 kb)
  • Tapping.jpg (41 kb)
  • Upper_Assembly.jpg (51 kb)
  • Adjuster_Shaft.jpg (47 kb)

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    66tiger

    Posts: 84
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    That's where the 1"-10 acme tap came in. I wanted to drill and tap the hand wheel, then use an acme threaded nut as a jam nut. So far, the cheapest 1"-10 tap I've found has been through McMaster-Carr at $146 each. Pretty painful. So far I haven't found one through ebay or anywhere else for less. If anyone knows of a source for one, cheap, let me know. A 3/4"-6 threaded rod would be an option, but I wanted a slower adjustment than 6tpi would give so I went for the 10tpi rod. In retrospect, the 10tpi conventionally threaded rod would have been a better choice for me from a cost stand-point.

    -- Arden

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    gapingghyll

    Posts: 24
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    Arden,

    Do you have a lathe - or access to one? You could make a one-time-use tap from some of the rod you bought. Depending on the carbon content, you could flame harden it - or case harden it. Just turn the end taper and the flutes can be ground with a die grinder or cut-off wheel (carefully) mounted to the tool post. Don't forget to protect the ways from grit. <smile>

    Just a thought to save some $$.


    Graham

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    66tiger

    Posts: 84
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    That's a great idea! I'll give it a try, thanks.

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    unklian

    Posts: 517
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    Another way,turn down the end of the screw until it's a light press fit in the handwheel.
    Press them together,then drill and tap the assembly,vertically,so that the centerline of the tapped hole is inline with the od of the end of the shaft.1/4-20,or larger,would be fine.
    You end up with half a tapped hole in each piece.
    Tighten a set screw into the blind hole,and now the handwheel can not turn on the shaft,
    but the pieces can be easily dissassembled if necessary.

    If the handwheel is softer than the screw,the drill will wander towards the softer material,
    so you might offset the hole slightly to compensate.

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    frank

    Posts: 46
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    I learned a lot tonight.Thanks to everyone. Attached is a drawing of a proposed idea for attaching the threaded rod to the inside tube of the adjuster. Basically, the threaded rod is turned down at the end which then goes through a plate on the top of the inside tube. A thrust washer is on either side of the plate. Then a collar holds the thing together. Is this dumb? I'm trying to be simple but probably overlooked something.
    Frank



    Attached Files:

  • adjuster.jpg (74 kb)

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    unklian

    Posts: 517
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    Looks good to me,as long as you have a way of securely fixing the collar on the shaft.

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    66tiger

    Posts: 84
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    That's a good idea, too. One of my concerns was in being able to take out any sloppiness between the shaft and the nuts. One idea was to turn down the threaded rod, sort like Graham did, and thread it for 7/8"-14TPI (assuming 7/8" is small enough to strip off the acme threads). That way I get away from the expense of the acme tap but still retain the means to tighten it up. The picture shows the idea. At least the top half, anyway.I still have no way to do the same for the nut in the inner shaft... Maybe there isn't enough there to matter.



    Attached Files:

  • Adjuster_001.JPG (46 kb)

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    rog02

    Posts: 84
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    Moderators, sorry to make work for you but I didn't have time to keep all my posts in the forum - where they really should be. Maybe one of you can round up the few stray Yahoo parts of this thread ( I wasn't the only one) and put them in the forum. I'll try harder in future. My excuse (as always) is that I'm only on dial-up. <sheepish smile> Thanks.



    I guess everything's relative. I bought the tap for my adjuster bushing (1 3/4 acme) on ebay for $25, and single point cut the shaft threads on my lathe to match. Not so hard.
    Wild Bill


    Arden, it's not 1"X10tpi, but I still have the 1 3/4 X 4 tpi tap I used for mine, which is available for loan. I don't know if you can buy a matching shaft, but I also still have the lathe tool I ground to cut mine also if you want.
    The nice thing about 4tpi is it precludes the need for a quick release, as one turn moves your shaft 1/4 inch. You don't have the sensitivity as with finer threads, but I haven't found that to be an issue.
    Wild Bill


    Thanks, Bill! I really appreciate the generous offer, but I've already got too much invested in the 1"-10 stuff I bought before I realized that I was looking at an expensive tap purchase. In the end, I may do what Graham did and turn down the end of the threaded rod and pin the hand wheel to the rod. Not a great solution, I'll admit, but cheap. I'm also trying to convince the machine shop where I work to thread the hand wheel for me, but it'll likely take 6 months before they can squeeze in my "government" job.
    Thanks again,
    Arden


    Arden
    There is no reason that the wheel has to be threaded onto the shaft. I personally like Ian's suggestion. Machine a size on size fit and pin it. You can always drive the pin out if necessary. That would probably never happen. Simple is best.
    Dick


    Arden,
    Well ... I try to help and what do I get? "Not a great solution". Indeed!
    Don't get too excited - I'm just kidding. I didn't take any offence. <grin>
    Actually I turned down the shaft so I could fit the hand wheel with a press
    fit and either a pin or a dog screw. I like to use taper pins because they
    don't work the hole oval like split pins and straight dowels do - usually.
    Taper reamers are pretty cheap. You drill the hole though the fitted parts,
    then ream the ass'y and drive in the pin. Easy to remove for service, too.
    I can't remember the real term for a dog screw. It's like a grub screw, but
    longer and it has a spigot on the end. The spigot engages a blind hole in the
    shaft and the hub of the hand wheel takes the threaded part of the screw. The
    ones I've seen and used, were made so the spigot was a light press fit in the
    blind hole and also bottomed out under the screw pressure. It's a little more
    convenient for routine service but the taper pin is more robust.
    Graham


    Graham,
    I'm going to have to proof my messages better. After I read what I wrote I
    realized that it didn't say what I meant, dang it! My apologies...
    On yours, the issues I've been wrestling with are addressed by the stripper
    bolts and concentric springs (I think that's what you're doing, anyway).
    I've been approaching the backlash problem from the direction of introducing
    some tension in the threaded rod between the hand wheel and the nut on the
    outside tube, but I realize now that I still haven't addressed any that may
    exist between the threaded shaft and the nut on the inner tube. I realize
    that all this would be a non-issue if I was satisfied with allowing the
    threaded rod and hand wheel to move up and down as I adjust the position,
    but I was trying to avoid that. Again, maybe it's not worth the effort.
    -- Arden


    Arden
    No sweat - I never thought, for a moment, that you meant what you said. <smile> E-mail is funny that way. Without tone of voice, body language, and a wink, it's not as easy to convey subtleties. I just took the opportunity to have a little fun with you. <grin>
    About the adjuster tension - that's exactly what I was trying to achieve. And it worked quite well - except that I should have figured (from the outset) on longer supports/bushings for the stripper bolts to ride in. There wasn't a lot of play - but just enough for the pressure wheel and the anvil to rock a tad at the pressure point - not good.
    If you look at the photo of the upper ass'y, you'll see the two (thick) mounting plates. The yoke fastens to the lower plate and the stripper bolts screw into it, also. The ball thrust bearing sits in the pocket on the lower plate, too. The spigot centres the screw in the thrust bearing and the pressure is taken by the land in the pocket and by the shoulder of the spigot.
    The upper plate is threaded for the pressure screw and the guide bushings are mounted in it. It is held to the upper arm of the frame and the lower plate can move up and down - on the stripper bolts and bushings. The pressure screw is held in compression by the concentric die springs trying to force the two plates together. The upper bushing/boss ass'y is simply to provide vertical stabilisation for the pressure screw.
    When I get it all finished (again!), if there's still a problem, I'll report back. This design was conceived at least eight years ago. If I were to do again, I'd use the same principle but I'd use a single concentric assembly - with the screw and a single spring inside a large diameter tube.
    Graham

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    unklian

    Posts: 517
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    What is the size of the existing hole in the hand wheel ?

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    66tiger

    Posts: 84
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    There is none.

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    unklian

    Posts: 517
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    Since the amount of torque required to operate an adjuster is relatively low,
    a minimalist approach could be to drill and tap the end of the screw,
    and the center of the hand wheel.
    Then assemble with a long set screw and some Loctite.
    If you tighten it enough,it won't likely come loose.

    OR
    drill and tap a pair of holes in the end of the screw,perhaps 10-24,
    and drill a couple corresponding clearance holes on the hand wheel,
    then bolt it on with socket head cap screws.
    Even if the screws came loose,the wheel can't pivot around 2 points.
    And you'd never shear a pair of 10-24 screws in normal use.

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    rog02

    Posts: 84
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    Another altenative to attaching the adjuster wheel.



    Attached Files:

  • Ewheel_Adjust_Wheel_Attach.doc (19 kb)

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    frank

    Posts: 46
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    Could an acme nut be turned down to a cylinder shape and then positioned in a hole bored in the center of a handwheel the same size and then brazed?
    Frank

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    unklian

    Posts: 517
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    That's another possibility,although some hand wheels have a plastic coating that wouldn't survive the heat.

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    pinkertonkap

    Posts: 39
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    Frank, if you put a nyloc nut as your top thrust washer, you will have backlash adjustability.

    Kerry Pinkerton
    wheelingmachines.com

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