Customizable PCP barrel band ?

[naptemp]

A barrel band is a relatively simple shape:
-top ring around the barrel
-bottom ring around the air tube
-middle part which connects the 2 rings
-optional, a picatinny rail on the air tube (bottom) part

All of the above can be defined by several parameters:
-length of band
-barrel diameter
-air tank diameter
-length of part connecting the 2 rings
-is picatinny rail present on bottom

We could also add screws to the middle part, but that may slightly complicate things.

I am a software engineer and vaguely familiar with OpenSCAD.

How hard could it be to generate an STL file for a barrel band using the parameters above?
Has anybody done something like that?

[WobblyHand]

How hard is it?  It's just work, at least if you know the CAD tool.  Making a parameterized model that scales nicely takes a while to do, but really the hard parts are making it work over a wide range of values.  Sometimes things just don't look right with a brute force scale.  Or you get into silly fastener issues.

If you don't have a grasp on the CAD tool, I'd say it is pretty tough.  Far simpler to just make one size, and fiddle with it until you like it.

Basically, if you are experienced, it's relatively easy, otherwise not.  Of course, don't let me discourage you. 

I think it would be a great way to learn the CAD tool of your choice, as you have a definite goal, and it's not an overly complicated part.

Your question is pretty open ended, in my opinion.  Are you asking someone to do this for you?  Or are you going to give it a try? Someone with a lot of experience could do this pretty quickly. 

Unfortunately I don't know OpenSCAD, but I do have some experience with FreeCAD.  This is not to say I could do it quickly, but I could get there in under a couple of days, because I've done similar things in the past.  Big thing is: the more options you add to the list, the hard it is to test that it works right.  Or in software speak: Just because it compiles, doesn't mean it works!

[naptemp]

How hard is it?  It's just work, at least if you know the CAD tool.  Making a parameterized model that scales nicely takes a while to do, but really the hard parts are making it work over a wide range of values.  Sometimes things just don't look right with a brute force scale.  Or you get into silly fastener issues.

If you don't have a grasp on the CAD tool, I'd say it is pretty tough.  Far simpler to just make one size, and fiddle with it until you like it.

Basically, if you are experienced, it's relatively easy, otherwise not.  Of course, don't let me discourage you. 

I think it would be a great way to learn the CAD tool of your choice, as you have a definite goal, and it's not an overly complicated part.

Your question is pretty open ended, in my opinion.  Are you asking someone to do this for you?  Or are you going to give it a try? Someone with a lot of experience could do this pretty quickly. 

Unfortunately I don't know OpenSCAD, but I do have some experience with FreeCAD.  This is not to say I could do it quickly, but I could get there in under a couple of days, because I've done similar things in the past.  Big thing is: the more options you add to the list, the hard it is to test that it works right.  Or in software speak: Just because it compiles, doesn't mean it works!

Thank you for the reply.
This was more of a rhetorical post, wondering how complicated could it be to make something generic enough.

I will have to learn a modeling tool at some point if I have the time.
I have tried Fusion360 in the past but gave up, since I found it too complicated.

[WobblyHand]

Most 3D CAD has a learning curve.  Some might say it is steep.  But I think it just takes some commitment, and a certain amount of bullheadedness to persevere.  There are a lot of video series on most of these tools. 

Pick your CAD of choice, look up the video series, and start practicing.  Actually, in the beginning, you simply need to follow along enough to duplicate what the video is showing.  If that means slowing down the video, or repeating it half a dozen times until you get it, that's ok.  The instructor doesn't care, or even know.  That is what I had to do.  You need to have the video in one half of your screen, and the tool in the other.  I rearranged my icons, so they were identical to the video, so I wouldn't waste time hunting them down while the instructor had moved on.  After a dozen videos, I could do quite a few interesting things.  Mind you, I'm no expert, but I can do enough CAD to get stuff done.  Honestly, I wished I had done this decades ago, as knowing 3d CAD would have helped me in my career.  But better late than never.

[naptemp]

Most 3D CAD has a learning curve.  Some might say it is steep.  But I think it just takes some commitment, and a certain amount of bullheadedness to persevere.  There are a lot of video series on most of these tools. 

Pick your CAD of choice, look up the video series, and start practicing.  Actually, in the beginning, you simply need to follow along enough to duplicate what the video is showing.  If that means slowing down the video, or repeating it half a dozen times until you get it, that's ok.  The instructor doesn't care, or even know.  That is what I had to do.  You need to have the video in one half of your screen, and the tool in the other.  I rearranged my icons, so they were identical to the video, so I wouldn't waste time hunting them down while the instructor had moved on.  After a dozen videos, I could do quite a few interesting things.  Mind you, I'm no expert, but I can do enough CAD to get stuff done.  Honestly, I wished I had done this decades ago, as knowing 3d CAD would have helped me in my career.  But better late than never.

Which CAD tool are you using and would you recommend it?

[WobblyHand]

I'm using FreeCAD.  I was using Linux, so there aren't that many choices.  It works well enough for me.  Done over a 100 designs with it, so it has proven it's worth to me.  I've 3D printed from my models as well as machined hard parts in steel.  The price is right, the help forums are good and it's multi platform which I ended up using.

There are a lot of videos on using FreeCAD.  I can recommend both Joko Engineering and Mango Jelly.  I learned the tool based on these videos.  One strong recommendation is to have two screens or windows up simultaneously and to follow along doing the same thing as the instructor.  There's so much new stuff that you have to physically do the things to get things to stick in your mind.  At least for me, I had to replay a lot (at reduced speed) to catch what the instructor had done.  If you don't do that, you won't develop the skills to do it yourself.  The lessons build up from the foundations, so it's important to get them. 

If you have any questions about getting going, let me know.

[avator]

I am in need of a custom barrel band. I used the GMAC repeater breech on a Maximus. Then I added a Fortitude shroud and baffles. The Fortitude barrel band squeezes them too close together.
I don't know how to use design software nor do I own a 3D printer. I have yet to inquire if there is anyone here with the ability and willingness to make one. I'll get around to it sometime after the holidays.
In my opinion it would only require 3 measurements. The 2 diameters and the overall OD of both combined including the space between.

[WobblyHand]

@avator, This stuff isn't too hard to learn Bill, even for us old dogs.  But it is work, and I could see you or others would rather be doing something else that is more fun.  Looks like your shooting games that you have been setting up would be a whole lot of fun.  Here, it is a bit on the colder side.

When you get a chance, measure up what you need, and I'll see if I can gin up a design.  A simple barrel band isn't hard to model.  What size fastener (screw) are you thinking of, and what style?  Socket head screw, or?  Make a pencil sketch of what you want, take a picture of it and send it to me via PM.

[avator]

Thanks Bruce...
Like I said, let's get through the Holidays and I'll get back to you.

[WobblyHand]

Thanks Bruce...
Like I said, let's get through the Holidays and I'll get back to you.

No problem.  I'm going to be a bit busy here myself.  My 4 YRO grandson, my daughter and husband are due here tomorrow.  My grandson's an over active little guy - always into something.  Spent today attempting to move "stuff" that might be hazardous if unsupervised.  Maybe in a year or two I can introduce him to AG's, he's a bit too young right now.

[avator]

Yeah, I remember toddler proofing the house. Pretty much anything that wasn't nailed down. But they would always still find something.

[subscriber]

I searched for an image of the the Fortitude barrel band and below is what I found, but it could be wrong. 

If the image is correct, then the Fortitude barrel band seems to have screws that push the shroud and air tube together.  Perhaps the screws should only clamp the air tank (indirectly to avoid dinging the tube), and leave clearance around the shroud to allow a little "free float" movement, but prevent so much movement as to tweak the barrel?

If free floating the shroud is desirable, a groove for an O-ring bumper could be included in a custom barrel band design, to cushion the shroud, if it is bumped into its travel limit.

[avator]

I searched for an image of the the Fortitude barrel band and below is what I found, but it could be wrong. 

If the image is correct, then the Fortitude barrel band seems to have screws that push the shroud and air tube together.  Perhaps the screws should only clamp the air tank (indirectly to avoid dinging the tube), and leave clearance around the shroud to allow a little "free float" movement, but prevent so much movement as to tweak the barrel?

If free floating the shroud is desirable, a groove for an O-ring bumper could be included in a custom barrel band design, to cushion the shroud, if it is bumped into its travel limit.

If I'm understanding you right, that's the way the Marauder was.
Let me clarify a bit, and you may already know this. The GMAC breech positions the barrel higher than a standard barrel band is designed for. I basically only use a barrel band to prevent too much movement in the barrel/shroud in the event of an accident such as a hard bump or drop. Tight on the tube and free float on the shroud is just fine with me.
The GMAC kit came with a barrel band that worked well before I added the Fortitude shroud and baffles.

[avator]

Tell ya what..
I'll get the gun out tomorrow, take some pics and get some measurements. I'll begin a new thread so as to not muddy this one any more. I'll direct you and Bruce to the new thread.

[subscriber]

Desired dimension would help a lot:  Air tube OD.  Shroud OD.  Desired gap between the two tubes from OD to OD.  Or desired center to center spacing.  Desired depth of barrel band, front to rear. 

I propose the "rings" around the tubes be 4 or 5 mm thick at the thin sections; rounded on the corners.  I propose the ring around the shroud have 3 mm ir 1/8" radial clearance.  You can have whatever you want.

I propose simple two screw retention against the air tube, but that has shaped printed plastic plugs that bear against the tube to avoid direct contact from screws damaging it.   If you want to reuse the current screws, what is their OD?  I am going to assume that the threads will need to be tapped, although we can try printing the threads, if you like.  Else, just starter holes in the print file.

Or, instead of screws to retain the band, just a tight fit on the air tube; so it has to be sprung open to get the tube in.  So a friction fit.  It might take more than one print attempt to get such a fit just right; not too tight; not too loose.

[avator]

There may be enough space between the tube and shroud to use a countersunk cross screw with an inlayed nut on the opposing side. Like I said, I'll get a closer look in the morning.

[Pellethuntr]

I design and 3D print custom barrel bands for people all the time. Like you said it's simple shapes and it's relatively easy if you can use CAD software proficiently.

[Duane38]

A barrel band is a relatively simple shape:
-top ring around the barrel
-bottom ring around the air tube
-middle part which connects the 2 rings
-optional, a picatinny rail on the air tube (bottom) part

All of the above can be defined by several parameters:
-length of band
-barrel diameter
-air tank diameter
-length of part connecting the 2 rings
-is picatinny rail present on bottom

We could also add screws to the middle part, but that may slightly complicate things.

I am a software engineer and vaguely familiar with OpenSCAD.

How hard could it be to generate an STL file for a barrel band using the parameters above?
Has anybody done something like that?

One major thing I learned making parks for co-workers and research...  If it doesn't require an optic, it's not critical. 

Made plenty of "mounts" for folks. 

[avator]

Ok guys... here is a link to what I need.

Again, my apologies to the OP for the misdirect.

https://www.gatewaytoairguns.org/GTA/index.php?topic=211976.msg156500973#msg156500973