Ball bearing spring guide, piston, and gluing in screws

Discussion in 'Gun Building, Modifications & Repairs' started by Dany0808, Nov 3, 2015.

  1. Dany0808

    Dany0808 New Member

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    Miami
    I know that a ball bearing piston guide and/or piston head are better than ones without. What I don't know is if both is better than just one, or is there no difference? Can something bad happen if you use both? Additionally, if I were to use the piston head without the ball bearings and the parts that hold them together, just the piston head and the screw, would it still work ok or would it need some weight? Also, do I need to glue in the screw in the piston? What adhesive would I use? Any other parts in the gearbox that I should glue in? How would I glue in the bearings? Thanks!
     
  2. MrGearbox

    MrGearbox New Member

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    Peoria
    For using a bearing spring guide and a bearing piston head at the same time, there is no danger. It would just add more compression giving you a SLIGHT boost in fps. Nothing to worry about. Just make sure to ALWAYS have bearings on at least one side (piston head or spring guide) for a healthier/longer lasting spring. And if you just want to use a piston without the bearings, and just the parts hold in the piston head, this would be fine as well. I have an m120 in my 35rps build with bearings on both the piston head and spring guide, and everything is perfect! As for adhesive, I would definently use some blue loctite on the piston head screw. For removal of "blue loctited" screws, it just takes hand tools and some force. There's not really a need for the loctite anywhere else in the gearbox unless you visually notice screws loosening themselves over time. Here's a pic of the loctite I use. [​IMG]
     

  3. DreadCo526

    DreadCo526 New Member

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    Sylvester
    Don't use bearings in the piston, they weigh average 3.5 grams plus lube so about 4 grams total. If you are going to spend all the time swiss cheesing your piston than you just went in reverse by using the bearings in the piston as you can normally only remove up to about 3 grams from the piston safely(the amount of material you can remove really depends on what piston it is and what setup you are using it in). The entire reason of a ball bearing spring guide is so that you don't have to use bearings in the piston, making it lighter weight, if you choose to use the piston with or without the bearings it will not hurt anything its just common since not too.

    As for what you should glue down in your gun. Parts I always glue down:

    -Your wires, use some super glue and this will keep them from coming in contact with your gears and or trigger.

    -Piston head screw, just use loctite

    -Spring guide components, don't glue the spring guide to the gearbox itself but there are different parts to a spring guide that can come loose if they are not glued down causing a world of hurt. Just use super glue, epoxy or JB welds.

    -Bushings, most definitely glue them down with either epoxy or JB welds.

    -Cut off lever screw, use loctite on it as well it can come loose.

    -You should seal your cylinder head to the cylinder by using RTV, you should do the same with the bucking to barrel.

    -All gearbox screws should be glued down using loctite, only after all the work is done inside the gearbox and you know that its working properly.


    All of these measures are taking to improve the reliability of your AEG, if any of these screws or components were to come loose than not only could damage be done to your parts but also you would have to take the gearbox apart every time one did.
     
    Last edited: Nov 4, 2015
  4. MrGearbox

    MrGearbox New Member

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    Peoria
    Totally forgot about the JB weld and totally agree with DreadCo526. Make sure you use JB weld around the bushing itself and hammer it into place. Make sure to wipe off any access and to clean the bushing holes themselves with some isopropyl alcohol while the jb weld is still wet. Q tips help a lot! And as for the bearings, they will counteract the Swiss cheesing, but that's if you are near hitting pme or actually hitting it. I have bearings on both sides in my 35rps aeg on an m120, the SHS 15 tooth is swish cheesed, and no problems. Maybe because it's an m120, but be careful with softer springs.
     
  5. Airborne101

    Airborne101 Well-Known Member

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    Chicago
    I also agree with Dreadco.

    Do not use bearings in the piston head. It will help reduce piston weight, and therefore stress on the pick up tooth of the piston/sector gear, and impact stress on the gearbox shell.

    Additionally, 2 sets of bearings are redundant. A single bearing allows the spring to rotate freely as needed.

    Thirdly, contrary to MrGearbox's statement of "no danger", 2 sets of bearings can cause your spring to bind. This is depending on the number of coils in the spring and their thickness. If the spring binds, your gun would lock up, fully compressed.
     
  6. MrGearbox

    MrGearbox New Member

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    Peoria
    My apologies Airborne 101... as I stated previously, one of my high rps ssg builds has been running fine with 2 sets of bearings. However the binding would make a lot of sense. I've just never heard of the issue...maybe its rare??? I'll make sure to verify facts on experiences next time. Others' experiences are always valuable! Thanks for the correction!
     
    Last edited: Nov 4, 2015
  7. Airborne101

    Airborne101 Well-Known Member

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    Chicago
    Im not sure i'd say it's rare, but it isn't unheard of either. You don't hear of it often because people are told not to run dual bearings, and generally they don't, so they don't run into this issue.

    I've personally had it happen when I was building a customer's gun and he dictated that he wanted bearings on the piston head and spring guide. While at the time I knew it was redundant, it did not occur to me that binding could be an issue.
     
  8. DreadCo526

    DreadCo526 New Member

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    Sylvester
    Airborne this is a new problem to me aswell, I have most likely had it happen to me before and not even know what actually caused the problem. Please explain how this would would happen? Heres my guess tho, your saying that the spring will not have enough room to compress because of the extra 7mm taken away by the bearings being placed inside the piston. So the same problem would be caused by spring spacers, right? Please confirm.
     
  9. MrGearbox

    MrGearbox New Member

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    Peoria
    That's true airborne, this was my first time hearing of spring binding. As DreadCo526 stated, an explanation would be greatly appreciated to an intermediate tech, at best, such as me.
     
  10. Airborne101

    Airborne101 Well-Known Member

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    Chicago
    Correct. You only have a limited amount of space within the piston for the spring to compress.

    We know that springs come in all different lengths, coil counts, and with different metal thickness. If you have have a spring with thick coils and more coils, then it will be longer than a spring with thinner coils or less coils.

    Effectively, the extra bearing can cause some springs to bottom out (thats a better word for this rather than bind) because the bearing will eat up the extra 7mm or so that the spring might need.

    So yes, the same problem can be cause by spring spacers. If you need or want to use spring spacers, measure the thickness of the metal of your spring, and multiply it by the number of coils. This will give you your fully compressed length. Then measure the length of space inside the piston. Subtract of the thickness of the bearing(s) if you have them, and that will tell you how much space is left inside the piston for the spring and any other "stuff".
     
  11. DreadCo526

    DreadCo526 New Member

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    Sylvester
    Yeah thats what I thought you were talking about, I will have to be more careful of this problem in the future as I do use spring spacers from time to time. Well thanks I appreciate it!
     
  12. weaps

    weaps Active Member

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    Brunswick
    I very seldom use piston bearings in my builds. When using a bearing spring guide always check to make sure that the spring guide bearing portion slides into the back of the piston easily. I've encountered some that were tight going into the back of the piston. An easy fix however, just lightly sand out the inside of the piston back for a loose fit.

    Also, if I should have to use a piston with bearings, I just use 2 steel washers at the end of the spring guide. I epoxy one in place and the other is placed loosely on top of that. This gives me the best of both worlds without taking up too much excess space.

    And as airborne said ALWAYS check compressed piston springs length so it doesn't bottom out.

    I also radius both of the piston springs' 2 end tips by lightly grinding and then polishing them. This assures me that the piston spring can rotate/unrotate freely under any condition.

    weaps.
     
    Last edited: Nov 7, 2015