Selecting baffles for a F1 build

[dallas_form1]

Hi all -

Looking forward to posting the project i started once it is finished and tested, but I am in a bit of a jam. I have the F1 back and in hand and need to fill my tube with baffles. I know I could go the freeze plug route, but would prefer to order some 60 degree cones or other cups to finish this out.

My issue is that my tube has a 1.39" ID. It seems the Cup or dry storage compartments have an OD of 1.37" to accommodate a ID of 1.375", commonly found in the titanium tubes. Over and over, it seems that the tolerance on the ID of a tube and the OD of internals hovers around .005". With my tube, this would be closer to .01".

My options are:
1. Make custom cups with an OD of 1.385"
2. Run cups with where the (ID of my tube - OD cups)/2 = .01 and over-drill the bore to allow for movement
3. Run the 1.370" cups and get a sheet of stainless shim roll to gap the last .05"

I have searched and can't find a similar topic, apologies if I am missing something obvious. Excited to post my project once complete, just want to finish it out before doing a long thread on it. This board has been a great resource and guide up until now - hoping someone has experience with this.

Thanks!

[T-Rex]

Why not buy a tube that has more common dimensions? You can always sell your's in the classifieds. Seems like a much better option, considering the availability of parts.

[dallas_form1]

The tube I form 1’ed was formerly a SureFire 7.62 trainer. The thing weighs a ton, but I got it in my head I wanted to see if it could be used as a start point and couldn’t get it out of my head. I’ll go back to stock components for the next build, but this was a (overly heavy and expensive) itch I had to scratch.

It’s OD is 1.5 but it is thin walled, hence the odd ID. I do think I’ll have issues with thread integrity when it’s complete. I don’t have high hopes for this - was hoping to use off the shelf stuff to complete rather than doing more custom work.

May just end up tossing a stack of freeze plugs in and calling it a day.

[a_canadian]

With your given parts I'd turn a bunch of spacers to make up the difference. Use thicker walled aluminum tube to match your tube's ID more closely and cut recesses for the baffles fore and aft. About 1/8" or a bit longer, T shaped cross section. A bit fussy to assemble but it would be stable, and allow you to keep the bore size as you prefer rather than going overbore.

[dallas_form1]

Indexed spacers will be the best option. Tried to form some
Freeze plugs, not sure how anyone can work with those. They are super soft and move around on you if you don’t have a machined forming tool.

I’ll post a write up on them when completed so nobody else tries to convert a SureFire trainer, really not worth the effort.

[MadGumby]

Are the trainers the same ID the whole way down through the tube or is there a taper inside?