Backhoe Contribution - theluthier - Digger Arm & Cab Frame

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Kent Trammell

This is a thread dedicated to the digger arm and cab frame parts of the backhoe project. Hardsurface modeling awesomeness 🤘

  • Shawn Blanch(blanchsb) replied

    Don't worry Kent. I'll keep your thread alive while you are on vacay!

  • Shawn Blanch(blanchsb) replied

    The Bucket on your Backhoe has normals inverted just FYI.

    Super easy fix but I thought I would let you know if you didn't notice already. (image below has back-face culling active).

  • Kent Trammell replied

    Thanks for resuscitating my lifeless thread blanchsb 😆

    It's a good time to be notified about the bucket normals. I finally started fleshing it out recently:

  • Kent Trammell replied

    Progress Update! I think I'm finished with the main pieces of the digger arm. Now I just need to do a final pass of the finest details (hydraulic lines, brackets, and double-checking for rivets/screws/bolts)

    The bucket's teeth took longer than I like to admit 😅

  • Kent Trammell replied

    Hydraulic lines have proven to be a fun, tedious, but rewarding process. Then I unhid the plate that covers most of it...

  • Shawn Blanch(blanchsb) replied

    Just think of how Adrian will feel when we cover the engine Lol

  • adrian replied

    If I don't bolt it down properly it will fall out the bottom for everyone to see. 

  • Shawn Blanch(blanchsb) replied

    Or you could do it like Tommy Boy way and leave the oil can in so that the hood pops at the most opportune time during the demo reel!

  • Shawn Blanch(blanchsb) replied

    @theluthier  I just had this thought while I was modeling my hydraulic lines.........is our current full model "true to scale"??? Because when I made a comment to use 3/4" lines in the live stream I believe that will only work if the rest of the DOG is 1:1 scale.
    I figured I would ask what the scale is before I go to town on all of my hydraulics.

    If it is not 1:1 that is no biggie but knowing what the current scale is: I could back-calculate the "scaled diameter" of 3/4 inch lines

  • Kent Trammell replied

    As far as I know our DOG is 1:1 scale. spikeyxxx pointed out last month that our scale was slightly off to which I corrected in the 3rd iteration of the master file.

    However I too was thrown off by the actual scale of the hydraulic lines as I modeled, especially when I found this video:

    Which is a zoomed in shot of this part:

    The fitting is way bigger than I estimated perceptually. However whenever I threw in a 6-foot human mannequin and placed his hand in the same spot, it didn't feel that far off:

    For the black lines (which seem thicker in photos) I've gone with 3/4" diameter and for the metallic lines I've gone with 1/2". What do you think blanchsb?

  • Shawn Blanch(blanchsb) replied

    That's funny I did the same thing. Black lines 3/4" and metal lines 1/2"

    It's like we are sharing the same brain waves!!!

    I wonder if those "larger than life" connection points are for ease of connection for operators?

  • Kent Trammell replied

    No way! Haha that's awesome 🤜💥🤛

    I wonder if those "larger than life" connection points are for ease of connection for operators?

    Good question. It really put the scale of the backhoe into perspective for me. The thing is a hossAnd the fact that the guy hand-tightened that massive fitting kinda blew my mind too.

  • Shawn Blanch(blanchsb) replied

    Yeah, I just realized you posted the video link. Yeah that is a specialized fitting for ease of installation. It looks like it has an O-ring for making a good seal and it is larger so that it can easily be turned and installed by hand. Larger diameter fittings are easier to fasten since you have more circumferential area to make a larger "moment-arm" to transmit your force. Now I am getting into engineering terms haha.

    Think of it like trying to pry up a heavy rock by your hand, then you grab a long and strong stick and use that to pry the rock. The long stick makes it easier because you get a long moment arm that takes most of the stress with little force from the user.

    If those fittings were smaller they would be harder to tighten by hand. And then the operator would have to carry a tool box/wrenches with him everywhere he goes (who wants to do that?!?)

    I like how they design those accessories for ease of use. That is really the "wow" factor that promotes a great user experience.

  • Shawn Blanch(blanchsb) replied

    Could you please send me a copy of your file so I can verify my tubing sizes? Or I can send you mine. Either way.

  • Kent Trammell replied

    Dude, super interesting. Makes total sense. Just when I start to marvel at our efforts to recreate a shell of this thing, the reality sets in that people designed every part inside and out. Bad. Ass.

  • Shawn Blanch(blanchsb) replied

    Based on the size of the black hydraulic hoses to that dude's fingers I am glad I said 3/4" for those black lines. They definitely look roughly 3/4" (if not slightly larger).

  • Shawn Blanch(blanchsb) replied

    Again unfortunately for @adrian2301 he doesn't have many "larger than life" fittings for the engine, ..........so wrenches and hand tools all the way. I know a guy at Cornwell tools and will cut you a deal.


    Looks like those special hand-tighten fittings are going to be for the digger and accessories parts.

  • Kent Trammell replied

    Haven't updated my thread in a long time. Last week I spent several hours adding many details to the cab frame:

     There's so many little bits and pieces I never noticed: Latches, handles, hinges, etc. All of which are made awkward by the subtle rounded contours of the frame and windows. Still only 75% done by my estimation.

    rryzen7 and ketre you have my continued sympathy for the complexity of this part! 😵

  • Karen Trevino(ketre) replied

    Your cab looks awesome @theluthier  I just want you to know I think you are my favorite teacher ever except for my 1st grade teacher.  I love that you teach when, why and how.  Give us the opportunity to make the attempt. But more than that when we attempt you tell us what's wrong and show us how to correct.  You say it to us in a way that doesn't hurt nor sound critical, and you are sincere. 

    To all the others involved I can say with honesty that after my first attempt at the cab I knew I was way out of my comfort zone. Yet I felt encouraged by you and the others to keep trying. For this I will always be grateful.  I have truly learned so much by participating.

    I'm ready to try something else tho...continue studying and learning what I set out to do.  Trust me when I say I'm not discouraged by this at all. When Kent said he's going to use his cab I felt such relief...haha

    The outcome of this project has so impressed me with what you guys have done!

  • adrian replied

    Well said ketre , I second that.

    I also have admiration for you ketre , for your determination and continued improvement. You have made great progress. 👍