37 replies to this topic

[KaneTheMediocre]

All the 3d printed parts are ABS plastic. If the part's are going to be machined, most plastics would be fine including HDPE. Just avoid the terribly weak stuff like acrylic and LDPE.

[Thorn]

I have access to a Makerbot replicator 2x, which has a print bed of 9.6 by 6. Would it be possible to print to print the pieces on this? And if so, would I have to modify the files at all?

[Draconis]

Something I've wondered - would it be possible to bend an eye into the end of the PR instead of trying to attach one? Aluminum should be way stronger than any plastic eye, and bending it into a 'good-enough' eye shape shouldn't be hard at all.

I was thinking exactly the same thing, but you beat me to it. Seems like it would be easy with a vice, wouldn't take as long as threading that end, and would actually give you something better to hold on to while threading the business end.

[Drev]

I was thinking exactly the same thing, but you beat me to it. Seems like it would be easy with a vice, wouldn't take as long as threading that end, and would actually give you something better to hold on to while threading the business end.

The problem with doing this would be attaching the catch piece to the rod. You need to have the threads cut in the front end to have the catch piece on there. Also, cutting the threads isn't that hard. I sandwiched the aluminum in a piece of folded cardboard and put it in my vise. After that, I used my die and it all went well.

[KaneTheMediocre]

Something I've wondered - would it be possible to bend an eye into the end of the PR instead of trying to attach one? Aluminum should be way stronger than any plastic eye, and bending it into a 'good-enough' eye shape shouldn't be hard at all.

As Drev noted, this would require a new plan for holding the catchpiece on the rod. Also, aluminum tends to break when bent at sharp angles, and it would be difficult (Not impossible) to not bend the rest of the plunger rod at all during this process. Mcmaster sadly does not carry aluminum eyebolts, as that would certainly be appealing.

[Draconis]

Yes, I had forgotten about the catch.

[Ryan201821]

I have access to a Makerbot replicator 2x, which has a print bed of 9.6 by 6. Would it be possible to print to print the pieces on this? And if so, would I have to modify the files at all?

Yes, that will work. You will have to print the handles in two halves since I believe a Replicator x2 doesn't have at least 170 mm of Z travel. You can chop an inch off or so on the bottom, which I may eventually do anyway. The handles are incredibly long as it is, so you could probably afford to save the space. However, those printers most likely have a 0.35 nozzle unless modified so you will have to print them in two halves regardless. Make sure you read the section on Printing your components and you should get an idea of the requirements of each print. Message me if you have questions or post here if its an obvious thing left out.

And yes to your second question as well. The consumer level 3D printers we use aren't that precise and each of them have their own little quirks. These types of printers only work as well as they are calibrated which means two alike machines will probably print slightly different parts.

The only way to combat this is make a print, see how it fits, modify the model, and print another one. All the models I have available for download have most holes being oversized since our printers make undersized holes by about .030-.040".

Edited by Ryan201821, 09 July 2014 - 04:30 PM.

[Meaker VI]

As Drev noted, this would require a new plan for holding the catchpiece on the rod. Also, aluminum tends to break when bent at sharp angles, and it would be difficult (Not impossible) to not bend the rest of the plunger rod at all during this process.

Perhaps a small pin drilled through the rod and inserted into the catch face?

As to bending it, yes, that is an issue, but I'd assume not fairly straightforward to overcome. Put the rod in a vice with just the desired hook-end sticking out and force that around something round?

Shoot though, if you're drilling holes anyway, might as well drill 2 and use a D ring or keyring instead of a hook.

[Naturalman7]

Another question.

Any issue with sealing the 3/4" screws in the plunger tube and redirect piece? I've found leakage around screws before.

Edit: Settings of the camera used in the firing video? I find it interesting that you can see the darts firing.

Edited by Naturalman7, 13 July 2014 - 12:21 AM.

[KaneTheMediocre]

Perhaps a small pin drilled through the rod and inserted into the catch face?

As to bending it, yes, that is an issue, but I'd assume not fairly straightforward to overcome. Put the rod in a vice with just the desired hook-end sticking out and force that around something round?

Shoot though, if you're drilling holes anyway, might as well drill 2 and use a D ring or keyring instead of a hook.

This is doable, but would make the blaster more difficult to take apart. I think for one of the bullPACs I used a set screw through the catchface into a small flat filed into the shaft, but that was with a steel plunger rod and it wasn't an easy blaster to work with. Still, if you absolutely cannot thread the shaft, these are solid options for similar bullpup blasters.

[Zorns Lemma]

Edit: Settings of the camera used in the firing video? I find it interesting that you can see the darts firing.

I believe it is a Canon T?i which shoots 50/60 fps. In addition, the darts are coated in corn starch to help them feed which gives a visible trail.

[Ryan201821]

Another question.

Any issue with sealing the 3/4" screws in the plunger tube and redirect piece? I've found leakage around screws before.

Edit: Settings of the camera used in the firing video? I find it interesting that you can see the darts firing.

I believe it is a Canon T?i which shoots 50/60 fps. In addition, the darts are coated in corn starch to help them feed which gives a visible trail.

Yes, it's a Cannon T3i I believe. The darts are coated in corn starch, so that may help with being able to see the darts, but I think the camera and the light we were in helped a lot too. That's probably the best experience I've had being able to actually film darts being fired and seeing them. We're planning on making some more videos like this.

And also yes, the redirect piece has a lot of different places for air to leak and we've pretty much encountered leaks in all the possible places. The blaster doesn't need to seal 100% or even close to that, nor does any blaster really so it's not that big of a deal, but I agree it's not optimal. The threads should seal well enough, so I'm thinking it's mostly the seal around the redirect piece and the plunger tube, but I could be wrong. Basically if you're trying to get a perfect seal (also with any blaster), you're wasting you're fucking time.



Also I just wanted to note to people that are interested in giving us suggestions, that price is a huge factor into what we build. Sure, people will suggest cool things that would work wonderful and great, but are really expensive, and will make the end product a lot more pricey to the consumer. We aim to try and make homemades that aren't $155 with milled/lathed/cnc'd components out of aluminum, so please keep that in mind.

[Ryan201821]

New updates.



Changed the ReDirectPiece again, this time to eliminate the internal rod seal to something a little better. We've replaced it with an o-ring on the outside (front) of the ReDirectPiece, sandwiched with a printed plate, held together by three #6 screws. The o-ring seals against the front of the ReDirect, and against one side of the printed plate. Instead of the o-ring being held center by the rod seal housing, it's now just centered by the plunger rod. It reduces cost by a small amount, but also lets the plunger rod have more play from side to side. The nylon spacers that were previously used for the old rod seal, were a very close fit with the plunger rod, meaning if the ReDirectPiece was off-center from the PT (or the hole is off-centered), your plunger rod would be "cocked" to one side and cause super friction and sub-par seal.

I've already installed it on a blaster that was already built, and it integrates into the existing blasters quite well. The blaster is designed to have lots of over-draw (this should be considered a feature), so the extra ~3/8" added to the ReDirect doesn't effect anything.



We also have plans to use a new eyebolt and eyebolt adapter. Since it seems possible to break the 10-24 eyebolts, we're changing them to #6-32 eyebolts, but made from steel instead of nylon. We haven't had one break, so this is mostly just a preventative measure. The eyebolt adapter obviously also changes, and instead of having printed threads capturing the eyebolt, there is a captured nut inside the printed part. The piece was also made thicker and wider to accommodate the change. My eyebolts are still at McMaster, but we'll be installing these later tomorrow to test them out. I'll also update the BoM (there were a couple errors, too) and the rest of the write-up this weekend to reflect the changes.

Edited by Ryan201821, 17 July 2014 - 03:03 PM.