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Scratch Build – In Progress Carbon one open frame chassis

Discussion in 'Project Logs' started by Modultra, 11 Dec 2020.

  1. Modultra

    Modultra What's a Dremel?

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    Hello everyone, after watching Alex make beautiful stuff on the YouTube I decided to get off the couch and make some cool pc stuff as well.

    This thread will document my build of an open frame chassis that I have designed. The idea of this chassis is that it is going to be very flexible in terms of what you can do with it. It can be oriented in a multitude of directions and has capability to have accessories attached on the perimeter. The Idea is that it uses a tubular frame on the perimeter that can allow attachment of brackets. The brackets allow you to attach almost any thing you want to the chassis perimeter. The chassis feet can also be attached to any of side of the chassis. The frame is made from 15mm carbon fiber tube with the end connectors machined from aluminum. The sheet metal parts most likely will be steel. The design has been done for awhile now, and I have just found time to work on it.

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    First up is the end connectors, These are are the most difficult part to machine so lets get that out of the way. They still need to go through operation 2 to trim the tab off the back but that is not done yet.

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    neSSa, IBMer, Boledile and 6 others like this.
  2. Cheapskate

    Cheapskate Insane? or just stupid?

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    Rescued from page 2!
    At first I thought I'd warn you about stress on the bottom tube, but then I scrolled down. :lol: Holy cr*p! If you are 5 axis milling brackets, you probably know what you are doing already. -Awesome.
    Also, welcome to Bit-Tech.
     
  3. Dr. Coin

    Dr. Coin Multimodder

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    Nice little trophy you got there.
     
  4. Nexxo

    Nexxo * Prefab Sprout – The King of Rock 'n' Roll

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    That's a clever idea. I really like that design.
     
  5. Modultra

    Modultra What's a Dremel?

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    Thanks Cheapskate, I'm a long time lurker here, I'm liking your Puddidium build a lot. I don't always know what I'm doing, so sometimes its just easier to make a prototype to see if things work. The bottom corner brackets will have a lot of torsion on the joint between the carbon and aluminum so I may need to epoxy them to keep from twisting. The issue I am already seeing is that the carbon tube varies on outside diameter by around +/-.003. This is causing one leg of the tube to be tight while the adjacent tube not as tight. Also the tube I bought was supposed to be 1.5mm wall but they sent 1mm wall on accident. I think the thin wall is compressing slightly so the fit is not as strong as it should be when I tighten the clamp screw.

    I like it anyway I have one sitting on my desk. It gave me the idea to possibly mount the chassis this way to a base plate, might look cool.

    Thanks Nexxo,


    I had to cut the carbon fiber to size, and cutting carbon fiber tube can be a bit tricky if you want it to look good. I have used a band saw and lathe in the past and both methods seem to splinter the tube. This time I tried a diamond cutting wheel and it seems like the best method I have used so far.

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    Next I am going to be making the feet. This part is started on the lathe with some 32mm 6061 rod turned to size, and finished a the mill. The method I used is not the best way to do this but it is the easiest. The slitting saw leaves a lousy finish but you wont see it when installed. I had to make a quick fixture to hold the part for the mill work. the slitting saw I had is 3 inch in diameter and I was afraid the saw would spin the part off of the bolt. I added a pointed set screw to keep the part from spinning and it worked ok. It leaves a little dent on the bottom but it also wont be visible when installed.
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    Over all the finish wasn't too bad. Getting the radiuses on the top and screw hole edges was a little finicky buy worked out ok. If your zero point was off even .003 the mill gouged the face.
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    On to the base plate, I was originally going to use 3/16 plate but all I had was 1/4 inch so that is what I used. I tried the double sided tape method to hold the part down to the table, however the part came off in the beginning of the hole roughing operation. I ended up bolting it down through holes I had already made and finished it off. Because it came off during roughing I wasn't able to face it properly so I had to sand it down to get an even finish.
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    Re zeroing the part after it flew off, notice the hole where it was roughing when it came off. luckily the part wasn't destroyed.
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    Finished part
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    I threw the feet and frame together to get a look at it. I think so far it is looking good. At this point im not sure what the finish will be on the aluminum? Im not sure if the aluminum should contrast or match the carbon fiber?

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    I am really liking the lean back config, I think it really adds something to the look.
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    Next I need to make the accessory clamps and start doing sheet metal parts. I really hate making sheet metal parts on a mill.
     
    Last edited: 21 Dec 2020
  6. Cheapskate

    Cheapskate Insane? or just stupid?

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    I love the super rounded off 45 degree corners. I'm stealing that for future designs. :D
    The option I was thinking about at first was to use solid rod on the bottom, with a square connection inside the corner bracket. -But that would involve grinding carbon... Yuck.

    :worried: You made me realize REAL machinists are watching my weekly crash-and-burn log.

    Edit: Contrast is good.
     
  7. Modultra

    Modultra What's a Dremel?

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    Grinding carbon fiber rod with square ends could work, albeit messy. However in typical fashion I will try the easiest thing first. And that is either epoxy on the ends or machining a filer plug of aluminum to slide inside the tube in order to keep it from collapsing as I tighten the clamps. I guess I wont know how bad the joint is until I get all of my parts mounted in the motherboard tray.

    Machinists/engineers are lurking in the shadows, even we need inspiration.
     
    Last edited: 27 Dec 2020
  8. spolsh

    spolsh Multimodder

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    Any progress in the last week ?
     
  9. ACTIVAT3D

    ACTIVAT3D What's a Dremel?

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    This looks incredible. I'm really looking forward to the progress with the radiator mounts. It looks so light and as if it wouldn't hold the load but it is carbon fiber after all, which makes it look even more impressive and like it's defying physics.
    Carbon fiber tubes were an option for my current build, but I was too scared. :D
     
  10. Modultra

    Modultra What's a Dremel?

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    Unfortunately no progress on this and probably not for awhile. My landlord notified me that I need to move out by the end of the month, so spending all my free time looking for a new space and making arrangements. Also took on some larger customer orders that need to be done before I move. Customers are always getting in the way of the fun stuff.
     
  11. Modultra

    Modultra What's a Dremel?

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    It is light, and very strong. I actually used a similar construction method on a drone frame I made awhile back. I can stand on the out runners and the motor pods would only sag a few millimeters.

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  12. spolsh

    spolsh Multimodder

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    good luck finding a new place then fella. I'm sure a bunch of us will be eagerly waiting when you get the chance to do more work on this :thumb::dremel:
     
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  13. Modultra

    Modultra What's a Dremel?

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    Had some time to work on this again, now that I am moved into my new shop. Nothing major, just making some of the accessory clamps and doing the second operation on the tube end connectors. I should have ordered the sheet metal by now, but I cant seem to make my mind up on some of the design elements. I cant decide how to make the GFX card bracket attach to the chassis as well as the tubing. I suppose I will figure it out eventually, but I'm not sure where I want the card to go yet so that is hindering progress. I'm also thinking of going a little overboard and designing a cpu heatblock for this build. I have always loved the look of Damascus steel and I think I want to use that as the main material for the block. I have never seen a Damascus cpu block before and I think the contrast in the steel would complement the carbon and aluminum well.

    I suppose I should buy some components now as well, any body have a recommendation for a ITX board? I kind of like the Asus Strix, but it is a little spendy at $360. The pc parts list should be quite short for this build, 1 itx board + processor, GFX card, one nvme m.2 hdd, memmory, one itx power supply, ddc pump and tubing + connectors.


    Here is operation one for the clamps. I do love me some 5 axis, it makes life soo much easier, especially when making prototype parts.
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    Here is the second operation where I cut off the flag from the rear that was left over from the first operation. Made a little fixture that the clamp could hold on while the back is cut off.
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    This is a similar work flow for most 5 axis parts. Do everything you can in the first operation and then buzz the left over material off in the second. Again I made a quick fixture to hold the part for operation 2.

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    Now that the end connectors are done, I'm not sure they are going to work. I don't think they will have enough clamp strength to hold the frame upright. I have the clamp screws quite tight and I can still move the tubing if I lean on it hard enough. I think the geometry of the clamp mechanism is not ideal. The carbon tube varies in diameter quite a bit, so an adjacent tube may be .005 smaller than its neighbor. This means that one may be clamped tightly while the other is slightly less tight. Ideally there would be 2 clamping bolts, one for each tube. This would allow equal clamping force no matter on the diameter variation of the carbon tube. its either that or just add some epoxy! Not sure yet, I suppose I will know for sure when I start mounting parts on the frame.
     
    Last edited: 15 Apr 2021
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  14. Cheapskate

    Cheapskate Insane? or just stupid?

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    Beautiful. :D
    OK, hear me out.. This is really ghetto, but put scotch tape on the tube ends, heat it up, and take it back off. The stickum should stay on the tube. This will give you some more grab.
    You can remove it with naphtha and toilet paper.
    Option B is a few layers of clear paint on the fiber. -Not sure if it was mentioned yet since the update took eons.
     

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