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  1. #1
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    Stretched Marzocchi fat fork

    Like many others I really want to try a suspension fork on my Pugsley. I have an older Marzocchi Z3 and a Z1 that I am going to use for this project. I plan to widen the fork to 135mm by making a new arch and crown for the fork.

    I can post a few pics after I get to the minimum 10 posts
    Last edited by Machinist; 01-24-2013 at 09:57 PM.

  2. #2
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    Just wasting a post to get up to ten.

  3. #3
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    The donor forks for the fat bike fork projectThe blue fork has a 135mm spacer to simulate the final width of the fat fork. The green one has standard 100mm spacing. I made the spacer so that I could make a few rough measurements at the 135 mm width.
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-10141.jpg  

    Last edited by Machinist; 01-30-2013 at 08:00 PM.

  4. #4
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    Both forks torn apart and ready to be modified. I removed the brake posts on the blue fork for practice. I hacksawed the posts off and then cleaned up the cuts on a lathe.
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-10142.jpg  

    Last edited by Machinist; 01-30-2013 at 08:03 PM.

  5. #5
    not FAT free
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    just make it good and people will ask You how much and if You can make one for them !!!
    ...and they will make You rich
    i'm glad that "fat addicted" machinist finally got good idea and is ready to make it happen!
    cheers

  6. #6
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    Wooden prototype arch to test fit over the tire. The final version will need to be wider at the top.
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-10144.jpg  

    Last edited by Machinist; 01-30-2013 at 08:01 PM.

  7. #7
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    The final aluminum arch after lots of sanding and some polishing. The arch on the left side is an aluminum dust shadow. I still need to remove some excess material from the back of the arch to save weight.
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-10145.jpg  

    Last edited by Machinist; 01-30-2013 at 08:04 PM.

  8. #8
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    Keep up the great work. Cool project
    Still cleaning my Fatback.
    It's a life style.

  9. #9
    Alaska Turner Mafia
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    Way to go. I've considered this myself as I have some older Z1 and Z2 forks around with the bolt-on brace. Just remember you're going to have to consider some limit to the full travel. The tires are so tall that they'll approach the bottom of the crown at compression.

    Anxious to see your results, so keep us posted.
    Deceleration Trauma is my middle name

  10. #10
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    The last pic seems to have failed. I will try a different pic.

  11. #11
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    This started out as the green Z1 fork. I found an old can of industrial strength paint stripper at work that removed the paint in about five minutes. The brake posts were also shaved off. The dropouts had been filed at some point in the forks life and they were crooked. I managed to set up the legs in a milling machine and take a skim cut to make them square again. The axle slots were also the old 9mm size and most rear hubs use a 10mm axle now. I cut them to 10mm while the fork was in the mill.
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-10146.jpg  

    Last edited by Machinist; 01-30-2013 at 08:06 PM.

  12. #12
    will rant for food
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    Nice.

    FYI there have been issues with the forum displaying images of recent, might not be your fault.
    Disclaimer: I run Regular Cycles (as of 2016). As a profiteer of the bicycle industry, I am not to be taken very seriously.

  13. #13
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    Thanks Drew Diller, I am not super computer savvy so I was blaming myself. I can make just about anything out of metal but computers baffle me.

  14. #14
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    Speed holes in the back of the arch to make it lighter.
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-10147.jpg  

    Last edited by Machinist; 01-30-2013 at 08:14 PM.

  15. #15
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    This is a prototype plastic crown so that I can figure out a few more measurements before I jump into a metal crown. I have a very special piece of metal that I have been saving for years, just waiting for the right project.
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-cimg0645.jpg  

    Last edited by Machinist; 01-30-2013 at 08:18 PM.

  16. #16
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    The grey coloured round bar on the back of the bench in the last pic is a 4 inch diameter 24 inch long piece of solid titanium. I just thought you guys might appreciate that info.

  17. #17
    gone walk about
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    well that asplains it.
    plus+, plus+ = win:

  18. #18
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    The new wider crown will be cut from a piece of solid titanium. It's not as light as an aluminum crown but I think it will be way cooler. I have sprayed a blue layout dye on the titanium and sketched a few rough measurements on it as I plan out the new crown.
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-cimg0639.jpg  


  19. #19
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    mmmmm titanium
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-cimg0641.jpg  


  20. #20
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    I'm picking up what you're layin' down. Keep it coming...Awesome project !

  21. #21
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    This is definitely looking awesome. I know myself and one other that did a fat conversion on these forks keeping the 100mm spacing (there's a thread on here about it). I can't wait to see the finished 135mm version, should be awesome and not be so limited on tire/rim combos.

  22. #22
    Nemophilist
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    Damnn...

    You're beating me to it. Ahhh... for lack of a DRO. I just don't trust that I could hit the marks without one. I also do not have the process for the super fine tolerance of the bore for the stanchions, let alone the steerer. Boring is such a difficult thing to master on any level, but nice clean high precision stuff is much tougher yet. At least for us garage hacks. If I could only hit 1.259 dead. Maybe I just have not experimented enough....

    Interestingly, there is a real black art to the whole cryo fit thing. They use highly sophisticated equipment to create and then measure all of that stuff. "Tenths" are absolutely critical. And yet, a lot of that high tech knowledge does not necessarily transfer to clamp fitting. I had a pretty in depth discussion with a friend who does this stuff for a living (you ALL know the company), and he really had no idea of how or if the cryo knowledge was useful. The whole idea made him nervous.

    Sit and study a modern cryo fit lightweight fork and you will see lots of subtlety in its design. There are some VERY important things going on there. None of it is by accident.
    Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
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  23. #23
    All Lefty's, all the time Moderator
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    Quote Originally Posted by Drew Diller View Post
    FYI there have been issues with the forum displaying images of recent, might not be your fault.
    So I'm not the only one with the issues? Seems none of my fellow mods know or heard anything about it, at least those that have gotten back to me on it...

    As for the OP's work? SWEET! Beautiful work, making me jealous over here with all that tooling. Keep it up, you're gonna be so stoked
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



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  24. #24
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    Regarding the cryo fit, I assume you mean for the steerer (if not simply press fit) and stanchions. Some of these older Marzocchi's have all three bolted in though, so I would assume the tolerance is not nearly as precise - am I wrong on that? I for one had a crown with all three bolted.
    As an aside, I have also press fit steerers in and out of crowns to make the steerer tube longer, it isn't that difficult if you have a simple hydraulic press (I know, everyone has one of those, right?!). The one I used was just welded up with a simple bottle jack and heavy duty iron for the frame - it was originally for AMP forks but I used it on Marzocchi's back in the day as well. I know I wouldn't do it multiple times to the same crown for fear of fatigue, but I never got nervous about a one-time press out and replace with a longer steerer.

  25. #25
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    Love this project. Fits my favorite equation nicely.

    Time + Toys = More and Better Toys
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  26. #26
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    Trailmaker, I don't have a DRO either. We have good old equipment at work and it's all dials for me. The bores on the crown were done by clamping the crown in a 4 jaw chuck on the lathe. I will post a few more pics when I get home from work tonight.

    woodi2259, I think it was your thread where I mentioned my plans to do this. Seeing your thread pop back up motivated me to start posting some pics.

  27. #27
    Nemophilist
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    Hey;

    Speaking solely of cryo fit, tolerances are ABSOLUTELY CRUCIAL. Clamp fit is not so crucial as to bore tolerance, but it is still very important and not to be minimized. Let's say going from a tenth or two fro cryo to perhaps a half a tenth or a little more. The most critical aspect of clamp fitting is the eveness of the clamping force. It is important to make sure the forces are distributed over the entire area evenly, and that must be considered carefully. The wall thickness of the clamp area, the thickness of the bolt flange, whether that bolt flange will maintain the same position relative to the clamp area, bolt torque, etc. The main focus is to make sure that the bore is round, and that it has at least a light press fit tolerance. If the clamp has any excess tolerance when it begins to compress, it will go ovoid in shape and introduce an uneven load on the stanchions. This is NOT a good situation.

    This is all based on current understanding and materials. Back in the day they just made things heavy and probably didn't sweat it. With all the light weight thin wall stuff, it gets really important.

    Pressing steerers in and put of alloy crowns is fine, I guess, but I would not do it without (the proper amount of) heat. You might get one shot at it cold, as the broaching out of the steerer bore in the crown would loosen the tolerance. Far less so with some heat expansion.

    I would guess if you were working with old clamp fit components, you would have more leeway on all of this.
    Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
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  28. #28
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    sick project! Looking forward to seeing this one develop

  29. #29
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    The new titanium crown is slowly starting to look like a crown. The new aluminum steerer tube was a good find on ebay.
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-cimg0714.jpg  

    Stretched Marzocchi fat fork-cimg0763.jpg  


  30. #30
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    Once again I can't see the last pics so hopefully this one works.
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-cimg0713.jpg  


  31. #31
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    Awesome.

  32. #32
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    Bwaaaaaaaahhhhhh!

    Awesomness.

  33. #33
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    you guys're awesome!
    not just because you're creative and resourceful, but also because you remind me of stuff I may have in the basement!!
    BLACKSPIRE SHOCK TOWER showing nearly 1/2" over a 3" gazzi on a 321 rim.

    seems to be about 380mm radius form axle to crown, how tall is a 3.8' knard again?
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-crownie.jpg  

    Last edited by byknuts; 01-24-2013 at 08:18 PM.
    If steel is real then aluminium is supercallafragiliniun!

  34. #34
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    I can't see the pics on my computer but i can see them on my wife's laptop so I am going to try a few more.

    The pics so far have been out of date, I have been working on this project for about a month and a half. I have limited time to work on the crown so progress is slow but steady. This set will bring you guys almost up to date.
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-cimg0798.jpg  

    Stretched Marzocchi fat fork-cimg0799.jpg  

    Stretched Marzocchi fat fork-cimg0800.jpg  

    Stretched Marzocchi fat fork-cimg0803.jpg  

    Stretched Marzocchi fat fork-cimg0805.jpg  


  35. #35
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    Really enjoying following this thread. Amazing work you are doing! I can't imagine how many questions you will get about that fork once you are done.
    By the way, let me know if you want to sell the old crown from that fork. I'm trying to revive an old bomber from my garage to put on my wife's fat bike and am looking for a crown.
    Keep up the great work!

  36. #36
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    byknuts, I remember those Blackspire arches very well. I had the Envy version of that arch on my old Jr T. If I didn't want the extra width I would have tracked down one of those arches.

  37. #37
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    I know you guys like custom made parts so I'm slipping in a pic of my bashguard. It started as quarter inch aluminum plate and I turned down the centre to shave a bit of weight. The rest of the bike is fairly heavy but who wants a heavy bashguard. I also cut a groove into the outer edge of the bashguard and then machined a matching piece of teflon to snap into the groove. The result is a super slippery edge that slides over trees and rocks.
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-cimg0509.jpg  


  38. #38
    Gumnut Peddler
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    Loving your bike porn! Good to see people doing amazing DIY stuff
    Burning fat, not oil.

  39. #39
    Fat & Single
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    Awesome work there Machinist !!!
    Trek 9.9 Superfly SL
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  40. #40
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    When can I order one?

  41. #41
    How much does it weigh?
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    Try hosting your images on imageshack.us... I love this thread, and it is nothing without the sexy titanium photos.

  42. #42
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    I can see all the pics now but if anyone is still having trouble I have also created an album on my profile, just click my name to find the pics. I have had no trouble uploading the pics there.

  43. #43
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    That is some awesome work.
    Oh noes. I'm going to drink the Kool-Aid.

  44. #44
    Mtn Biker Machinist
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    So cool!

    I love seeing DIY machining projects for bikes. I built the upper crown for an old Judy DHO, and while a challenge, it was tons of fun!

    Can't wait to see the finished fork. Looks awesome so far.

    frog

  45. #45
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    It's about time, someone did this.

  46. #46
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    Approaching the problems from perspective of a framebuilder insead of a machinist, I have contemplated making a widened fork crown built much like a segmented tube steel fork (ala fat chance), but with super-short (2") fork blades that pinch-clamp the suspension stanchions to the crown. Someday...

  47. #47
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    Wow, this is awesome! Keep up the good work and keep posting pictures.

  48. #48
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    Thanks to everyone for all the great comments. I can feel my ego growing by the minute.

    I would also like to mention that all my work is done on full manual machines. We have no cnc machines at work and I have actually never used one. I go by the dials on the machines and also some very accurate magnetic backed dial indicators that I stick to the machines. The milling machine does have a digital readout but it can't always be trusted.

    I promise a few more pics later today but I have to go do some trail building right now.

  49. #49
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    The End Mill cutter on the right is brand new with sharp corners. I hand ground a radius on the left cutter so that there will be no sharp corners when I use it to cut the crown. It's not easy to get a nice radius when grinding free hand. 1 1/8 diameter cutter.

    There is always time for one quick pic.
    Attached Thumbnails Attached Thumbnails Stretched Marzocchi fat fork-cimg0771.jpg  


  50. #50
    Puro Vida!
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    Very nice! I

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