Tuning Spacers for FX Carbon Fiber sleeve on FX Crown MKII

[bd2021]

So I came across danny5692's post on spacers for the FX Carbon Fiber barrel sleeve. His design looks great especially when resin printed. He was kind enough to share his design file so I tried to print it on an FDM printer. However, I did not have good luck due to dimensions and minimum thickness in my slicer, so I designed my own.

My first design was this:

However, after shroud installation over the spacers, I noticed that they slide up and down on the CF sleeve...probably due to fiddling with them too much. So I put some electrical tape to lock the spacers on the sleeve.

This worked well but I didn't like the tape because it is a bit kludgy, even if nobody can see it once the shroud is installed.

So I went back to the drawing board and made a longer spacer shaft so that it will have more friction between it and the sleeve:

I tested by putting the shroud on and off a few times with the o-rings and it worked a lot better without electrical tape holding the spacers to the sleeve. Even without electrical tap it retained its position on the sleeve where I placed them.

However, I did not glue the CF sleeve to the barrel, so I still needed to put electrical tape on the barrel to hold the CF barrel sleeve / spacer assembly to the barrel when removing the shroud.

I didn't do such a great job on the tape here but you get the picture...

Anyway, I shot a magazine and the scope retained center and even though I can't say there was an issue without the sleeve and the stock FX barrel spacers, when I learned about the CF tube I figured it has got to help.

Now I just need to find a CF shroud to make the FX Crown look more pimped out.

 

[qball]

 Design work. However, IMHO the primary function of the carbon liner sleeve is to get rid of those spacers. I use one factory spacer at the very end against the carbon sleeve so the position would not change. Also having only one touch point at the end I’m hoping it would behave more like a free floating barrel, best would the barrel free floating inside of the shroud but not sure if FX shroud is strong enough to avoid clipping with a moderator installed. but I had great luck with just one spacer at the end in my superlite barrels, in theory it should almost behave like a free floating barrel. 


Although the difference between the 2 designs could be very small if any. 

 

[bd2021]

Thanks qball

 

[qball]

Thanks qball

I just want to reiterate that is just MY THEORY so could be completely wrong! Plus I have a hate hate relationship with those spacers including the rubber orings in STX barrels. 

 

[bd2021]

It is not a bad theory, and worth my consideration. I'm thinking about it.

Do you just let the CF sleeve float on the barrel, or did you epoxy it?

By the way, you definitely want to fix the front of the sleeve or barrel to the shroud somehow if you use a DonnyFL.

 

[biohazardman]

IMHO;

I think the carbon tube was meant to stiffen the barrel and get rid of the o-rings, in the steel barrel housing, by doing so.

I don't believe it was meant to get rid of the shroud spacers on the Crown Superlight barrels.

 

[bd2021]

I'm not sure what you mean, but something certainly needs to keep the barrel and sleeve centered in the shroud. The barrel spacers did that, but they don't fit on the CF tube. I think qball has a good point than maybe only one is needed. I know from experience that something is needed.

 

[Scotty1]

When I put the carbon fiber sleeve on my 500mm crown barrel, I used a spaced, barber pole style wrap of Teflon tape to achieve a tight fit. It was very snug going on and took some twisting in the direction of the wrap, so as to not bunch the Teflon while installing. 

 

[srtmat]

Those spacers look really nice.
I just picked up a 3D printer and have been keeping it busy making airgun parts. I’ll have to put some of those on my list to make.

I installed a carbon sleeve on my short 380mm liner . I epoxied mine on. Without being able to tension them like the Impact guys can I felt it wasn’t tight enough to really do anything just being slid over the liner.

I use one spacer at the end and I turned one out of delrin for the middle which probably isn’t needed . I tested with and without the middle spacer and saw no difference in accuracy so I left it in.

 

[bd2021]

That looks really good @srtmat. Any tips on epoxying it? I don't want to make a permanent mistake. Fortunately I happen to have some really good but slow curing epoxy. Unfortunately it dries white.

 

[bd2021]

Well, I have just epoxyed mine (600 mm), just because I didn't have tephlon tape in my workshop (just lazy, impatient). I read elsewhere people are concerned about different thermal coefficients of expansion between the barrel and the CF sleeve, so I'll keep an eye on that. Oh well hope I didn't make the wrong decision.

 

[Greg_E]

The epoxy will help stiffen the assembly.



I really want a large resin printer, don't have room right now.

 

[bd2021]

I want a CNC machine, but if I can't have that, I am thinking about an SLS 3D printer. Resin looks too messy for me (even SLS). 

 

[3DAirgunWorks]

I printed my centering rings in tpu and left offd the oring. Tpu is a flex material and in my opinion my dampen harmonics.

 

[MEC17670]

Those spacers look really nice.
I just picked up a 3D printer and have been keeping it busy making airgun parts. I’ll have to put some of those on my list to make.

I installed a carbon sleeve on my short 380mm liner . I epoxied mine on. Without being able to tension them like the Impact guys can I felt it wasn’t tight enough to really do anything just being slid over the liner.

I use one spacer at the end and I turned one out of delrin for the middle which probably isn’t needed . I tested with and without the middle spacer and saw no difference in accuracy so I left it in.



View attachment 202988View attachment 202999

Is that 1 long piece of CF or 2 broken at the middle spacer?
I'm working on a 600mm barrel. 25 cal. and can't find a full 600mm CF tube which would be ideal for fitting with 1spacer at the muzzle. Any sources for a full 600mm CF tube?
I was also thinking of a spacer by the breech , glued, then CF tube glued to the sleeve , then a tightly fitted snug spacer, unglued for expansion, then finished off with a glued CF tube , glued, then with a unglued spacer. Thoughts?
Thanks,
Mike

 

[srtmat]

The CF sleeve on my 380mm liner is one piece. I ordered a 700mm carbo tube and planned to sleeve both my original STX and my Superior.
700mm is just long enough to cut in half for 2 380mm liners.

 

[danny5692]

Best way to make a snug fit for items like this, is to make three 'bumps' on the inside. 0,1 more or less, depending on the difference. This way of clamping around the carbon sleeve will always work fine.

 

[Mrshosted]

I want a CNC machine, but if I can't have that, I am thinking about an SLS 3D printer. Resin looks too messy for me (even SLS).

Why worry about cnc for this type of project. A manual lathe would do a wonderful job.

 

[Tomiboy]

Anyone selling these?

 

[srtmat]

I finally got around to designing some spacers and I thought I would share the file for those with 3D printers.
I decided to make mine out of TPU and eliminate the need for o-rings.
My carbon liner O.D. measures 11.9mm from my understanding that is pretty standard.

TPU Superlight spacer carbon sleeve by srtmat

FX barrel spacer for liners that have carbon fiber sleeves. This was designed to use on my FX Crown MKII with Superlight barrel .25 Cal. My carbon sleeve O.D. measures 11.9mm These will slide on quite hard, I used Isopropyl alcohol and a twisting motion. You want them tight so the don't...

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