flashforge for high-tensile strength parts

[jamesinvents]

Hi All,

Long story short, I have just been given a nice chunk of change to play with by a generous investor. As an avid hobbyist spearfisherman, one of my long time dreams has been to make inexpensive, but effective parts that fill a specialty niche within the sport. In particular, my current idea is to try to design and manufacture my own working roller muzzles.

A roller muzzle is a device that permits a speargun to be loaded with up to 1.5X the power one could with a normal muzzle on a gun of the exact same length. It accomplishes this by acting as a pivot point or fulcrum around which the speargun bands literally roll on grooved wheels. This in turn allows one to attach a longer rubber than one normally could, on the underside of the gun. The rubber is routed up from its anchor point through the muzzle, and attached on the other side of the gun barrel via a 'wishbone' to the spearshaft, which is hopefully securely lodged at this point in the gun's trigger mechanism housing. A roller muzzle thus confers numerous advantages. The most notable of these for me, as a shore diver, lies in having a shorter, more maneuverable gun with the range and power of a much longer one. This permits accurate snap shots, which can effectively prevent a diver from losing opportunities on larger and more desirable fish that blow by at close ranges. This is a significant improvement over a standard configuration, especially given the additional friction involved in maneuvering a long, handled object underwater.

I have not designed one yet, but the basic idea of the type I want to make is simple: place an axle through a speargun barrel endplug, oriented perpendicular to the barrel, and deck the axle out with bolt-on rollers. The metal hardware is relatively cheap and easy to find (rollers, bearings, bolts, etc.), but on the retail market, the plastic or fiberglass muzzle lends the finished product a high price tag. As an aftermarket part for pipe-style spearguns, these are sold for no less than $90.00, which is very steep IMO.

Anyhow, here are my questions:

1. Is it at all reasonable to think that one could create a functional part, minus the metal rollers, with a $1200.00 Flashforge printer? Keep in mind that the muzzle would have to work essentially as a fulcrum or pivot-point bearing a significant load, up to 200 lbs., in stretched rubber force, and also potentially at a weak point per my current rough design, i.e., a metal bar or axle inserted THROUGH the muzzle.
2. If this is indeed feasible, what sort of material/medium would be good to use? I have a hunch that ABS might have some desireable properties, but ultimately be too soft.
3. After investing in the printer and the proper media, what could I expect to pay in costs per unit for an item weighing say 200-300 grams?

Lastly, I know this is sort of a pipe-dream, and that is exactly why I've come here with my questions. But I have to imagine if someone can make a functional lower receiver for an AR-15 using a 3D printer, a speargun muzzle shouldn't be too far fetched.

Anyhow, thanks in advance for your input.

Best,
James

P.S., I've attached a bunch of images to help demonstrate some common designs as well as the concept.

[RobH2]

I like your idea and I believe that ABS or Nylon would be strong enough. You'll have to do some tests to see how much pressure per sq/in is on the rollers. A stretched pullback pressure of 200 pounds will have a different value when pulled over a roller as you'll be carrying all of that force on a very small surface area. What 3d printing is fantastic for is prototyping. I'd say make it out of ABS and then assemble one on a bolt. Get a tension scale that reaches much higher than 200 pounds and start pulling down on the standard rubber band. Be careful but keep pulling until something breaks. You might want to set a video camera up on the scale and pull remotely somehow with a come-along or something. The video will capture the force at the time of failure and you'll be far enough a way to not get hurt. At that point, depending on what failed, you'll have some good info. If the rubber breaks at 600 pounds and the bolt and ABS are intact I'd say you are good to go. If the ABS (I'd start out printing a solid part first) fails at 225 lbs, well, then it's not the best solution.

No matter what, if the design of the idea works then use 3d printing for what it's best for. That's for prototyping. Get the design right and then find someone to take your 3d printed parts and have 100's manufactured by injection molding or casting. The per unit costs will be a little higher but your delivery times will be better. If it takes you 5 hours to print the parts then you and only make 2 a day (for a normal work day length). If you think that this will be a low volume and on-demand thing that should be ok. But, if you anticipate that this will be flying off of the shelves, you won't be able to keep up. 3d printers, even the best ones, are not really fast enough for mass production. If you do print the final part yourself you filament costs will be a few dollars. It's hard to tell how large these things are but filament is cheap. You get a lot out of a 2kg spool.

I think you have a great idea. Fortunes are made by people who fill unique niches. I think you are on to something. I think ABS might just do it for you too. Just be sure it doesn't fail by splitting at a layer. Maybe print them horizontally in halves and ABS glue them together so the layers run top to bottom and can't split under the weight of the rubber. Just thinking out loud. You'll just need to experiment but I hope you go for it. I think it a perfect project for a 3d printer.

[jamesinvents]

I like your idea and I believe that ABS or Nylon would be strong enough. You'll have to do some tests to see how much pressure per sq/in is on the rollers. A stretched pullback pressure of 200 pounds will have a different value when pulled over a roller as you'll be carrying all of that force on a very small surface area. What 3d printing is fantastic for is prototyping. I'd say make it out of ABS and then assemble one on a bolt. Get a tension scale that reaches much higher than 200 pounds and start pulling down on the standard rubber band. Be careful but keep pulling until something breaks. You might want to set a video camera up on the scale and pull remotely somehow with a come-along or something. The video will capture the force at the time of failure and you'll be far enough a way to not get hurt. At that point, depending on what failed, you'll have some good info. If the rubber breaks at 600 pounds and the bolt and ABS are intact I'd say you are good to go. If the ABS (I'd start out printing a solid part first) fails at 225 lbs, well, then it's not the best solution.

No matter what, if the design of the idea works then use 3d printing for what it's best for. That's for prototyping. Get the design right and then find someone to take your 3d printed parts and have 100's manufactured by injection molding or casting. The per unit costs will be a little higher but your delivery times will be better. If it takes you 5 hours to print the parts then you and only make 2 a day (for a normal work day length). If you think that this will be a low volume and on-demand thing that should be ok. But, if you anticipate that this will be flying off of the shelves, you won't be able to keep up. 3d printers, even the best ones, are not really fast enough for mass production. If you do print the final part yourself you filament costs will be a few dollars. It's hard to tell how large these things are but filament is cheap. You get a lot out of a 2kg spool.

I think you have a great idea. Fortunes are made by people who fill unique niches. I think you are on to something. I think ABS might just do it for you too. Just be sure it doesn't fail by splitting at a layer. Maybe print them horizontally in halves and ABS glue them together so the layers run top to bottom and can't split under the weight of the rubber. Just thinking out loud. You'll just need to experiment but I hope you go for it. I think it a perfect project for a 3d printer.

Thanks very much for the input and encouragement. If I can ask another question, do you think the FlashForge is a good printer for the price? Also, per what you've written, is the turn around really as slow as 2 to 5 pieces per day, given a relatively streamlined design on a 200 to 300 gram item? Thanks again.

[jimc]

200-300g is 1/5-1/3 of a standard roll. time really depends on the part itself and your settings but in general if in fact you are burning 1/3 a roll of abs that sounds like a 16hr print....give or take. you would be easily only 1 to 2 per day. its just a guesstimate though. too many factors come to play.