Far Revisited, 700 rounds, a solid model, and SLA Options

[boltsniper]

The FAR is about 4 months old now and I have put about 700 or so rounds through it. I have been extremely happy with its performance and reliability. I rarely have and failures to feed and have had no major issues that could not be easily fixed during battle.

I recently had a free day with nothing I really "had" to do so I disassembled the rifle to inspect the parts for wear. Everything looked fine except for some small fatigue cracks on the bolt. It hadn`t failed yet but would have have eventually. I filled the cracks with glue and that should suffice for now but eventually it will need to be replaced. This is not something I had anticipated but it makes sense. I spent the rest of the day modeling the rifle in CAD. I`d been meaning to do this for a while now but never had enough time.

Here are some images of the solid model

















The rifle is modeled completely, with the exception of the screws. 25 parts were modeled separately and then assembled to the complete rifle. Applying the proper constraints the action can be cycled in the CAD enviornment.

There was another reason for creating the model. We received a new Stereolithography machine in my lab at school. Stereolithography is a process of making 3D parts out of a liquid or powder substrate. The machine inputs CAD files and creates the part to very tight tolerances in a relatively short amount of time. SLA machines are mainly used for rapid prototyping of concepts. The resulting part is not intended to be extensivelt used or used at all. I`m not sure yet of the material properties of cured SLA fluid. I may try making a solid bolt with the SLA machine and try it in my rifle.



I may regret the following, but.....

I may be able to produce FAR bolts and other parts through SLA for potential builders. This will depend of course on the viability of using a SLA produced part in the rifle and also the cost of the fluid and ability for me to use the machine. I wouldn`t charge much. Price would depend on if I have to pay for the fluid (which isn`t cheap).

If I get more than 5 PM's, IM's, Emails, or any other inquiries regarding this I will delete the above paragraph and deny everything. Trust me, if and when I find out more about this I will start a new thread at which point you can express your interest.

If anyone wants to see a closeup of anything on the solid model I will be glad to post the image. If anyone wants the part files I can send them.

This post has been edited by boltsniper: Jul 24 2005, 09:31 PM

[VACC]

You are one handy son of a bitch.

[KirbySaysHi]

Those are some very nice CADs... the first shot reminds me of the cheap digitized photos of babes that are displayed on video poker machines in bars... the difference being there aren't any pretty ladies...

Copy!

[Shotty_Master]

Those are real nice CAD drawings Bolt. I think you selling parts, or possibly even kits, would be awesome. only if you want to though.

[Arcanum]

Agreed, I would like it if you sold parts, but again only if you are willing to.

[rylundo]

i agree with the two comments above

[boltsniper]

If it turns out to be relatively easy and inexpensive I have no problems will providing people a few of the more complex parts. I dunno about kits...... It all depends on if the cured material is strong enough. It`s prett durable but I don`t know if it willl hold up to the impact forces.

[blakmoose1234]

just sell some flippn' FARs for like $90 each!

[Robonerfer]

He doesn't have the time to make multiple FAR's, owing to the unfortunate application of things like "real life" and "work". Not having to make the bolt would be awesome, I would also like it if you made a redesigned (sp?) FAR using Ompa's schweet new clip which shoots micros.

[merlinski]

Rapid Prototyping is the shiznit. We have a lab for it in the engineering building at Brown as well, tho I haven't gotten a chance to use it yet. However, I'm pretty sure that the prototypes aren't going to stand up to the kind of impact forces you're talking about.

Very nice CAD work. I'm seriously impressed. What program did you use and what if any training in CAD did you receive? I'm still relatively new at it, and it's frustrating as hell to get used to the interface.

Instead of looking to Rapid Prototyping, I'd suggest trying to machine a bolt out of aluminum or steel. Once you have the CAD files for the bolt, it should be relatively easy to machine it from a blank, assuming you have access to the right machines.

[boltsniper]

The solid model was done is SolidWorks. Beleive it or not I`ve had no official training in CAD. We were given Mechanical Desktop as Freshman at Tech and I played with that . For my senior design project we had to present a solid model of our aircraft. No one in my group knew CAd so I was designated to do it. I was using Unigraphics at that point in time and just sat in front of the computer for about two days playing with it. I started using SolidWorks when I started graduate school and I find it to be the best one I`ve used. All three have dramatically different interfaces and part building methods. There are really only about 6 features you need to know to create almost anything you can imagine.

I would tend to agree with you on the durability of the SLA produced parts. THe previous rapid prototyping machine we had used a powder substrate and injected a bonding agent at the appropriate locations. It produced very accurate parts but they were incredibly fragile. The SLA machine we have now uses a thermosetting resin as the substrate. The resulting parts are much more durable. More than likely they are not going to be durable enough to work as a bolt but I`m not going to rule it out until we actually make something with it.

Aluminum would definitely be strong enough but we do not have a CNC machine on campus that I could use for free. An aluminum bolt wold be just too heavy anyway.

[merlinski]

We use PTC ProDesktop at my school and the biggest problem I've had has been lining components up. It uses a pretty complex "workplane" system, and it's hard to assemble components in three dimensions to the specifications that I'm looking for.

[boltsniper]

SolidWorks and every other solid modeling program I have used have some kind of mating and constraint tool. During part assembly you can designate where parts should be in relation to others. For instance with the FAR most of the components are nested within eachother. All these parts are mated to eachother with a concentric constraint. The program automatically positions the parts according to the mate. Because the constraint is in place those particular parts now have constained motion....ie the bolt sliding in the receiver. You can further constrain parts by adding more mates. To position the barrel in the receiver I first applied a concentric mate to the barrel and receiver which placed the barrel on the centerline of the receiver. To fix the barrel in the right position I applied another mate that placed the front edge of the receiver and the front edge of the barrel spacer coincident. The program automatically places the part according to the mates. You never have to worry about distances and spatial relations.

More images after tweaking the model some.....











This post has been edited by boltsniper: Jul 25 2005, 06:49 PM

[flamebo388]

You just helped solve a problem I've been having with the rod that the action spring connects to. Mines too short and keeps flying off the bolt. Too bad I don't have my far right now. Those are some nice models of the gun, you should add them to the plans to help potential builders.

[taita_cakes]

Hey Boltsniper, nice CADs

Don't mind me, just having a joke.