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Thread: First Muller... (a winter project)

  1. #221
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    Quote Originally Posted by J. Vibert View Post
    Hey I did stuff for the muller project today.

    Fired up the lathe and finished the "axle" tube. Would post a pic and describe the activity but I haven't sorted out how I'm going to manage my online photos as of yet.
    Hey, I redid the "finished" work on the axle tube..lol

    The original efforts mentioned in the quoted post used some smallish bearings that were re-purposed from a drill press rebuild I've had on the back burner for a year or two. The problem with what I had done was my inner struggle with how to manage the top end of the muller arm mechanics. That, and the small id of the small bearings made developing the drive shaft difficult. Long story short, I had some much larger tapered roller bearings that I was of course hoarding for some special purpose but could never figure out what that was. Figured I may as well use them in this app. This meant of course cutting off the current top bearing housing, (as it was too small for the larger bearings) and enlarging the bore on the bottom half.
    The enlarged bore on the bottom and the new top that hasn't been pressed into place yet:
    IMG_20180208_091134.jpg
    The new bottom bearing installed:
    IMG_20180208_145751.jpg
    The replacement top end with bearing:
    IMG_20180208_145738.jpg
    IMG_20180208_142958.jpg
    Note on the above pic the addition of a o-ring groove. At this location there will be a feature on the muller arm hub that will overlap that shoulder and o-ring. I plan on working in some traditional bearing seals to prevent contaminants from working its way into the bearings, but figured including this feature would only increase the odds of sand screwing up my bearings.

    The new bearings have an ID of 30mm and the gearbox accepts a 25mm shaft. The plan is to design in the preload nut for the roller bearings at the bottom of the "axle" between the gearbox and muller floor. This will make the machining of the drive shaft far simpler for me. The very top of the axle shaft will be splined/keyed to mate with the clutch plate.

    sketches to follow...
    FLAME ON...!!!!

  2. #222
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    Stole even more shop time yesterday...

    Managed to get the "improtant" stuff done on the drive shaft:
    IMG_20180212_073113.jpg
    -So I have the 25mm portion of the shaft to size for the gearbox. This will still require a keyway.
    -Then a 30mm journal (1.181") for the lower bearing. This journal appears extra long because I still have to thread the shaft to apply preload to the assembly.
    -A section of reduced diameter just so I'm not pressing the top bearing a full 190mm to reach the shoulder it sits against.
    -Another 30mm journal for the upper bearing.

    The un-turned top portion is still in mental development. Meaning, I'm not exactly certain how I'm going to deal with how the shaft travels through the muller arm assembly. It will be reduce in diameter, but I have no idea how much yet.
    FLAME ON...!!!!

  3. #223
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    Well I went and did it again... I fab'd myself into a corner...lol.

    I need to cap the top portion of the axle and was hoping to install a traditional bearing seal as well. The 'cap' will endure the downward force of the spring clutch loading on the muller arm. ....Damn, I didn't consider the muller arm loading on the first couple of concept pics I threw together... Well I'll post them anyway...lol

    Current cross section:
    withoutCap.jpg
    First thought:
    withCap.jpg
    The idea above is that the "cap" is retained between the pressed on bearing and the shaft shoulder. I don't want to turn the shaft down more in this location, so there's a reduction in thickness so bearing won't be displaced too badly and sit short on the journal.

    My second thought after realizing this needs to support the weight of the muller arm:
    SupportCap.jpg
    So this one has the cap slip over the top section of the drive shaft and seats itself against the opposite side of the shoulder that the bearing does. The round stock I'm working with that will sit on this cap has a bored hole of about ~35mm ( i think ). I'm thinking I'll turn down the shaft to this dimension and base everything off of that. That said, the die spring I hope to use slips nicely over 30mm so there will be some more work later down the road.
    FLAME ON...!!!!

  4. #224
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    Ok... so I was a little bored today..., and I wanted to have something "on paper" if you will so I could actively brainstorm my approach. Posted below for your viewing pleasure..:

    The Muller Arm Assembly:
    MullerArmAssembly.jpg

    Clear as mud...?
    FLAME ON...!!!!

  5. #225
    That helps greatly with my own plans for a muller. (Still in planning/budgeting - saving up money - phase.)

    Better drawing than I can do, and it matches well the 'picture' I have in my head.

    The only difference I can think of is that the muller 'arm' has a recess which covers the 'capstan' tube. Since my welds tend to warp, I had thought to cast the capstan proper, as well as the muller 'arm' (and possibly the trailing arms, but those are another 'page' in the drawing collection)

    Dennis
    Last edited by den; 02-14-2018 at 03:59 PM. Reason: Sleep deprivation mistake
    Ouch! That stuff's hot!

  6. #226
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    Quote Originally Posted by den View Post
    Better drawing than I can do, and it matches well the 'picture' I have in my head.
    Well I have Inventor, SolidWorks, and SketchUp at my disposal, and I found I could do a faster job with MSpaint...lol.

    The only difference I can think of is that the muller 'arm' has a recess which covers the 'capstan' tube. Since my welds tend to warp, I had thought to cast the capstan proper, as well as the muller 'arm' (and possibly the trailing arms, but those are another 'page' in the drawing collection)

    Dennis
    Well for me, the goal is to have zero welds, as I suck badly at welding...lol. ....So the two piece (top/bottom)"capstan" will have an appropriately sized channel milled out of it to allow for a single piece muller arm. The drive shaft will extend through the arm so that will retain its positioning but I'll most likely use some fasteners as well to hold it fast.

    Same pic with some "invisible" lines to help illustrate the arm/shaft/capstan assembly:
    MullerArmAssembly2.jpg

    Anyways... Right now I'm trying to source a piece of material (aka: scrap) to make the top bearing cap. I have aluminium but want something more robust. I'm also struggling a little bit with the thickness of this part. I measured the hollow round stock I'm going to fabricating the capstan out of and if I want a snug fit to the drive shaft (for keeping everything square) I only have 7mm of material to remove to create a shoulder for the cap to rest on. 3.5mm worth of shoulder isn't much, so I'm back to considering placing the cap between the bearing shoulder and the bearing. Not the end of the world I suppose. Just means I really should turn a little more off the drive shaft to accommodate the cap. Thinking it needs to be .250" in thickness at the minimum to maintain some level of rigidity.
    FLAME ON...!!!!

  7. #227
    The weird thought I had for the one I hope to/am planning to build is to simply have the cover be part of the arm itself, and overlap the uppermost part of the capstan with a 'close' fit - and then 'seal' the upper bearing with the excess of grease applied (on a frequent schedule, via a zerk fitting) oozing out of the bearing.

    See (hopefully!) Included .pdf file
    Attached Files Attached Files
    Ouch! That stuff's hot!

  8. #228
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    Well I think I may completed my last "what the hell was I thinking" recovery part today. I had to pull some cash out of my pocket for sake of material, but it saved me several hours of bs.

    The upper cap for the axle was never an after thought, but may as well have been. Even this morning, I was mid way through the turning of the stock and about to part off what I had done before I realized an important aspect that would have ended up costing me my time invested and material. After I caught my yet to be made blunder I sketched up what needed to be done and took some measurements.
    IMG_20180218_134028.jpg
    What I missed was the flange height on the outer circumference of the cap. Because of some real time by the seat of my pants fabracobbling, I didn't think to make the bearing height match the shoulder I made for sake of the o-ring installation. What I ended up with was an outer flange that needed to reach down further than the bulk of the rest of the part. That made my approach to creating this part slightly different. I won't go through all the details, but in the end I had to bore out the cup to the groove OD of 3.110" with a depth of the difference of .085" (.004' allowance gap), then part it off so the main body would be .300". From the lathe it went into the mill and I used the rotary table to mill the groove to the .160" depth. Some with appropriate tooling would have turned the groove in the lathe. I don't have any trepan tooling and didn't want to waste a bunch time attempting to grind one, for a one time use.
    IMG_20180218_161242.jpg
    The part ended up being nearly bang on. It clears everything fine and floats a whisper above the bearing flange as it should. "Nearly" because I turned the flange OD to near perfect dimension and then because of some rotary table binding ended up climb milling against it. It still fits fine, and with a light coating of grease will be sealed more than well enough.

    Next up is a little clean up of the capstan material and finally turning/threading of the drive shaft.
    FLAME ON...!!!!

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