CTI nozzle holder not going over nozzle. (75mm)

Discussion in 'Propulsion' started by BryRocket, Jul 30, 2019.

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  1. Jul 30, 2019 #1

    BryRocket

    BryRocket

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    Hello,

    I have one particular nozzle holder that I just can't get over the nozzle (75mm). It's as if the internal O-ring groove isn't deep enough. I have another one that I've used many times without this problem. This is only the second time I've used this holder. I've tried a few different o-rings with the same result. Last time I had to sand a chamfer into the edge of the nozzle to get it on and went through several o-rings as it kept cutting them up. Has anyone had this problem? It could be a little variance in the nozzle or the internal groove isn't deep enough.

    Thanks,

    Bryan
     
  2. Jul 30, 2019 #2

    jimzcatz

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    Is it black or gray?I have a black one with the same issues.
     
  3. Jul 30, 2019 #3

    BryRocket

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    The holder is gray. Same color as the other gen 2 closure stuff.
     
  4. Jul 30, 2019 #4

    Dave A

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    Yes, I had the exact same issue with 54mm nozzle holder.
    Find someone that has one, mic the insides of the nozzle holders, yours may need turning. You can put the o-ring in each of the grooves and see if the reveal looks the same.

    The nozzle holder slides over the nozzle easily without the o-ring?

    I assumed you have the correct o-ring?
     
  5. Jul 30, 2019 #5

    BryRocket

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    Yessir. Thanks for the reply. What motor has a 54mm nozzle holder? I haven’t come across that yet.

    I’m confident I have the correct CTI o-ring in the inner groove. And yes, the nozzle holder slides easily over the nozzle sans o-ring.

    It appears the groove is about 1 radius of the o-ring. I ordered a bunch of these same o-rings and they all seem the same.

    It’s weird. Don’t have this issue at all with the other holder that looks exactly the same.
     
  6. Jul 30, 2019 #6

    BryRocket

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    I wish I could compare the other holder but it’s currently built up.
     
  7. Jul 30, 2019 #7

    BryRocket

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    IMG_3398.jpg
    IMG_3399.jpg

    I just can’t for the life of me get it on. I’ve started to sand/chamfer the nozzle. Hopefully I will be able to get it on. I also emailed CTI about it.
     
  8. Aug 1, 2019 #8

    jimzcatz

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    CTI had a line of 54mm motors designed for snap ring hardware. That's what used the 54mm nozzle holder. Unfortunately they have discontinued these motors.


    I may be mistaken, but I don't remember the internal oring being orange.
     
  9. Aug 1, 2019 #9

    BryRocket

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    All the 75mm reloads I’ve bought over the last few years have come with the orange oring for the internal groove and black ones for the external grooves. CTI was super duper cool and thought the internal groove might just be a little too shallow so they are sending me a new one free of charge. Great customer service.
     
  10. Aug 1, 2019 #10

    Dave A

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    What was the dash # of the o-ring that you bought for the inner groove?
     
  11. Aug 1, 2019 #11

    BryRocket

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    It says on the baggie that the orings come in with the reloads. I’ll have to look tomorrow when I get back to where they are.
     
  12. Aug 1, 2019 #12

    Dave A

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    If the bag is labled and packaged by CTI, the wrong o-ring could still be in there.
     
  13. Aug 1, 2019 #13

    BryRocket

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    The orings included with CTI reloads on top of my bag of like 500 others that I bought after I bungled several getting that nozzle holder on.

    IMG_3428.jpg
     
  14. Aug 3, 2019 #14

    Dave A

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    Yes, 228 is the right one.
    CTI nearly duplicated dimensions on their 75mm loads so most would work in AT cases.
    I have always used the nozzle holder AND inner o-ring on an AT reload in CTI, although the AT video doesn't use it.
    I find it more likely the the nozzle OD is slight too big.
    Only way to tell is get a caliper and mic the OD of the nozzle and the dimensions of the nozzle holder. I have plenty I can mic to help you compare.
     
  15. Aug 3, 2019 #15

    Dave A

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    If the OD is too big, as was on one of my 54mm CTI loads you can turn it down on a lathe.
    I did not have one so I found an arbor for a grinding disc. You can take 2 plywood centering rings and a threaded rod to make an arbor.
    I cut mine with a wood wrap and then finish with rough to fine sand paper.
     
  16. Aug 3, 2019 #16

    mikec

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    I'm confused about what the problem and the solution was. The groove was too shallow on the nozzle holder so they sent you a smaller O-ring that would fit better? Or they sent you a new nozzle holder with the right groove? Or they sent you a new nozzle with a smaller OD?
     
  17. Aug 4, 2019 #17

    Dave A

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    Looking how much of the o-ring is revealed when in the inner groove, that sounds like the answer.
     
  18. Aug 4, 2019 #18

    BryRocket

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    They sent me a new nozzle holder. They think the inner groove wasn’t deep enough. The holder easily slips over the nozzle without an inner oring but once you instal the oring it will absolutely not go on.
     
  19. Aug 4, 2019 #19

    crossfire

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    Have a dealer check it out. Something seems strange.
     
  20. Aug 10, 2019 #20

    BryRocket

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    Just received my new nozzle holder and it went on easy and worked like the other. The ID of the RING is the same but the groove for the oring was deeper on the replacement.
     
  21. Aug 10, 2019 #21

    rharshberger

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    Cool, should be easy to have a machinist deepen the groove on the one you have if CTI doesn't want it returned of course.
     
  22. Aug 12, 2019 #22

    Cameron Anderson

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    With the new nozzle holder, how difficult was it to slide the holder over the nozzle? I was assembling a CTI 75 yesterday and I couldn't get the holder over the nozzle by hand. It went on when I torqued the retaining ring in but not before then.
     
  23. Aug 13, 2019 #23

    Wayco

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    I built an M840 6 grain yesterday, it's a lot easier if you have a spacer and can put the forward end on the floor. That way you can get your body behind it. Went right on for me. The hard part was grain bonding...
     
  24. Aug 13, 2019 #24

    Cameron Anderson

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    M2020 6-grain with grain bonding...i did the same thing with my spacer and it still took effort. Next time I bond, I'll make it a two-person job, one for gluing grains, one to handle the liner and o-rings.
     
  25. Aug 13, 2019 #25

    Wayco

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    Cleaning up the liner was the hardest part of that job. Fortunately, I took considerably longer than ten minutes for the epoxy to cure. Did you have a lot of excess epoxy?
     
  26. Aug 13, 2019 #26

    Cameron Anderson

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    I used Gorilla Glue with one gloved hand to rub glue on the grain and one ungloved to handle the liner. I got the glue portioning right after the second grain so there was some excess but not a ton. Once it dried the next day i sanded any errant glue off with 220 grit then wiped down with a wet cloth. Worked fairly wrllm
     
  27. Aug 14, 2019 #27

    BryRocket

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    Not too difficult. There was still a lot of resistance but it went on. The old one would not, and I mean would not, go on.
     

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