Acme conformal rail guide question

[Nathan]

I'm building a Madcow 4" fiberglass DX3 XL. I would like to use Acme conformal rail guides from Giant Leap Rocketry but the closest they have is one made for their 3.9" phenolic tubes. Has anyone tried using a 3.9" Acme conformal rail guide on a 4" tube? Does it fit okay? I'm thinking that only the edges would touch the 4" airframe tube instead of perfectly conforming to the shape. But not sure if it would still be okay when attached with epoxy.

 

[Tim51]

I'm building a Madcow 4" fiberglass DX3 XL. I would like to use Acme conformal rail guides from Giant Leap Rocketry but the closest they have is one made for their 3.9" phenolic tubes. Has anyone tried using a 3.9" Acme conformal rail guide on a 4" tube? Does it fit okay? I'm thinking that only the edges would touch the 4" airframe tube instead of perfectly conforming to the shape. But not sure if it would still be okay when attached with epoxy.

I've used 3.9 Acme conformals on both 'glassed and unglassed 3.9" Loc tubes, as well as 'glassed 4" PML phenolic, all without problems. I've also used the the 3" ones on a variety of 3.0/ 3.1" tubes (eg PML phenolic wrapped in carbon fibre, Loc tube wrapped in fibreglass) again, no problem. There seems to be a degree of tolerance. I use a liberal amount of JB Weld to attach, and fillet well.

 

[Wayco]

You can also wrap a piece of sandpaper around the airframe tube and sand the guide to fit it perfectly.

 

[Nathan]

You can also wrap a piece of sandpaper around the airframe tube and sand the guide to fit it perfectly.

Good idea, I'll try that!