Best Rail Guides for Surface Mounting on High Velocity Rockets

Discussion in 'High Power Rocketry (HPR)' started by BryRocket, Aug 6, 2019.

Help Support The Rocketry Forum by donating:

  1. Aug 6, 2019 #1

    BryRocket

    BryRocket

    BryRocket

    Well-Known Member

    Joined:
    Jun 19, 2017
    Messages:
    333
    Likes Received:
    61
    Hey y'all,

    I'm needing to make a decision on what rail buttons/guides to use for a 54MD rocket. I've considered using fly-away guides but have opted for permanently affixed options. I have printed my own a few times using PETG material and haven't had one fail yet but I also haven't pushed one Mach2+. I'm concerned they wouldn't survive. Does anyone have any good recommendations on such a guide that is preferably conformal, surface mounted and is durable enough for higher Mach flights? Has anyone flown PETG printed guide to high velocities? I generally attach my surface mounted guides with Proline.
     
    MNay likes this.
  2. Aug 6, 2019 #2

    3stoogesrocketry

    3stoogesrocketry

    3stoogesrocketry

    Well-Known Member

    Joined:
    Feb 26, 2012
    Messages:
    1,116
    Likes Received:
    57
    I've machined a set of brass buttons for a 3 inch 7600 minimum diameter flight. The rocket shreaded at mach 2 ( clam shell nose cone collapsed ) but the buttons showed no sign of damage.
     
  3. Aug 6, 2019 #3

    BryRocket

    BryRocket

    BryRocket

    Well-Known Member

    Joined:
    Jun 19, 2017
    Messages:
    333
    Likes Received:
    61
    A type of metal rail guide would work good I'd assume. Do you make and sell them? I don't have any way to machine metal.
     
  4. Aug 6, 2019 #4

    mrwalsh85

    mrwalsh85

    mrwalsh85

    Well-Known Member

    Joined:
    Apr 30, 2012
    Messages:
    801
    Likes Received:
    45
    Consider the impact of metal guides on your club's equipment. Metal buttons could nick, mar, otherwise damage the rail, causing issues for other flyers. Plastic/nylon buttons are cheap compared to the cost of replacing a 12 foot stick of 1515.
     
    BryRocket likes this.
  5. Aug 6, 2019 #5

    mikec

    mikec

    mikec

    Well-Known Member

    Joined:
    May 9, 2009
    Messages:
    2,007
    Likes Received:
    85
    I use Acme aluminum guides. If they're in good condition and aligned correctly I don't see how they could damage a rail.
     
    Mugs914 and BryRocket like this.
  6. Aug 6, 2019 #6

    BMAT

    BMAT

    BMAT

    Well-Known Member

    Joined:
    Mar 18, 2011
    Messages:
    48
    Likes Received:
    14
    I've seen more damage to rails from sparky motors than any wear from an aluminum rail guide.
     
    Brent, rcktnut and BBrown like this.
  7. Aug 6, 2019 #7

    3stoogesrocketry

    3stoogesrocketry

    3stoogesrocketry

    Well-Known Member

    Joined:
    Feb 26, 2012
    Messages:
    1,116
    Likes Received:
    57
    Yellow Brass is self lubricating on a microscopic level. 6061-T6 has a Brinell hardness of 100 to 107 . Yellow Brass has a Brinell hardness of 85 to 95 . The brass will distort and get damaged before the aluminum will.
     
    Brent likes this.
  8. Aug 6, 2019 #8

    rcktnut

    rcktnut

    rcktnut

    Well-Known Member

    Joined:
    Oct 26, 2009
    Messages:
    1,437
    Likes Received:
    81
    Gender:
    Male
    Location:
    Sheboygan WI
    I have 2 1010 rails that are 15+ years old, been many Acme rail guides run thru them, they are just fine. I would say probably a good thing to run some of them thru a rail, clean all the other crap off of them. Don't know who came up with the idea that they damage the rails. If someone can say they damage the rails then I can say that using "softer" materials for guides than what the rail is will build up on the rail.
     
    Brent likes this.
  9. Aug 7, 2019 #9

    BryRocket

    BryRocket

    BryRocket

    Well-Known Member

    Joined:
    Jun 19, 2017
    Messages:
    333
    Likes Received:
    61
    Alright. Thanks for the input. I ordered a set of the ACME ones. Looks like a good recommendation.
     
  10. Aug 7, 2019 #10

    SammyD

    SammyD

    SammyD

    Forum Supporter TRF Supporter

    Joined:
    May 18, 2011
    Messages:
    596
    Likes Received:
    51
    Gender:
    Male
    Location:
    Wilmington, NC
    I find the ACME guides to be awfully long for my 2", 3", and 4" rockets, so I cut them down to about 1/2" in length and bevel the leading edge (see photos). In that way they more closely resemble a rail "button" in the contact area. Why did I do that?

    Moving a rocket up and down a rail by hand caused me to feel like there was too much contact area with the rail for a guide that was some 1.5" - 2" (from memory) long. Here's a photo of a 54mm diameter fiberglass kit with the ACMEs on it. The base area that attaches to the airframe is about 1/2" long while the portion that interlocks with the rail is about 1/4" to 5/16" long.

    The other advantage to this is that I can get 6-8 guides out of a pair of standard ACME guides... :)

    IMG_5749[1].JPG IMG_5750[1].JPG
     
    BryRocket and Mugs914 like this.
  11. Aug 7, 2019 #11

    cwbullet

    cwbullet

    cwbullet

    Obsessed with Rocketry Staff Member Administrator TRF Lifetime Supporter Global Mod

    Joined:
    Jan 24, 2009
    Messages:
    21,931
    Likes Received:
    1,200
    Gender:
    Male
    Location:
    Glennville, GA
    You can also 3d print Acme like rail buttons.
     
  12. Aug 7, 2019 #12

    cherokeej

    cherokeej

    cherokeej

    Well-Known Member

    Joined:
    Feb 16, 2009
    Messages:
    824
    Likes Received:
    38
    For extreme flights, there's always the tower option.
     
    Steve Shannon likes this.
  13. Aug 7, 2019 #13

    Mugs914

    Mugs914

    Mugs914

    Well-Known Member

    Joined:
    Oct 1, 2012
    Messages:
    570
    Likes Received:
    100
    Gender:
    Male
    Location:
    Temple Texas
    +100 on Acme rail guides. I do mine the same way Sammy does and have never had a problem. I think you'll like 'em.

    20190713_171104.jpg
     
    BryRocket and SammyD like this.
  14. Aug 8, 2019 #14

    BryRocket

    BryRocket

    BryRocket

    Well-Known Member

    Joined:
    Jun 19, 2017
    Messages:
    333
    Likes Received:
    61
    I’ve printed a number for other projects but I was concerned about the PETG holding up in its time spent above Mach 2. Have any experience with that?
     
  15. Aug 8, 2019 #15

    BryRocket

    BryRocket

    BryRocket

    Well-Known Member

    Joined:
    Jun 19, 2017
    Messages:
    333
    Likes Received:
    61
    Agree. I’m glad Sammy recommenced then.
     
  16. Aug 10, 2019 #16

    Rob702Martinez

    Rob702Martinez

    Rob702Martinez

    Forum Supporter TRF Supporter

    Joined:
    Dec 30, 2015
    Messages:
    837
    Likes Received:
    76
    20190810_143022.jpg Full length Acme guides pinned with 3/16 steel rod sections to the airframe. Bonded with JBweld. Cut the pins to insert into airframe butted against motor tube and slightly taller then the guide. Creates a mechanical connection. Made the holes drilled very close tolerance almost having to press the pins in. They formed a nice fillet on top of the guide.
     
    BryRocket likes this.
  17. Aug 11, 2019 #17

    Mugs914

    Mugs914

    Mugs914

    Well-Known Member

    Joined:
    Oct 1, 2012
    Messages:
    570
    Likes Received:
    100
    Gender:
    Male
    Location:
    Temple Texas
    I do mine a little differently, but the result is similar.

    I drill through the center of the rail guide (between the ears) and the tube where it will be mounted, That way the JB Weld squishes out through the holes forming a solid rivet.

    To be honest, both methods are probably overkill. If the surfaces are prepped correctly the JB Weld should be plenty strong enough for anything that would use Acme guides.
     
    BryRocket likes this.

Share This Page