roboman's Content

#334726 Any one intrested in 3D printed parts

Posted by roboman on 12 October 2013 - 08:25 PM in Homemades

I'm mostly confused as to why you're charging a premium on first-runs, as there is no real setup time involved in printing, other than the few minutes it takes to run the model through a slicer and generate the code for your printer.

#334384 Homemades Picture Thread

Posted by roboman on 30 September 2013 - 09:57 PM in Homemades

I revised the pump grip CAD for the pumpbows to make it printable without support material, and had Lucian print it for me today. He says it's comfortable.

Full Album Here

#334306 Ultrafire 14500 protected issues

Posted by roboman on 28 September 2013 - 02:42 PM in General Nerf

For the record, the protected cells have circuitry inside of them to limit the maximum current output of each cell - this is done because lithium batteries can explode or catch on fire if they're discharged too quickly. For our purposes, it's fine to use the unprotected cells, because the protection has a fairly high safety factor built into it, which limits the maximum current draw to less than a desirable level for electric blasters. The protection also limits the minimum cell voltage, so you don't permanently damage your batteries (or cause a fire) by taking the cell voltage below the absolute minimum for the battery chemistry. Lithium batteries are very picky and can tend to be volatile, but if you're reasonably careful, you'll be fine.

#334084 3k Tank Issue

Posted by roboman on 17 September 2013 - 01:11 PM in Modifications

It's possible, yes. You might want to put a washer under the screw's head. Just make sure it's not long enough that it tries to push the pin out of the plastic.

#334081 3k Tank Issue

Posted by roboman on 17 September 2013 - 12:56 PM in Modifications

It's not generally an easy fix. You basically want to get some sort of an adhesive between the pin and the rubber part (super glue works, if I recall correctly), but in order to do that without getting that glue on the sealing face, you typically have to open up the tank. You might be better off just replacing the tank, if you can get a spare from someone. I've actually been having this same issue with the latest batch of 2K tanks, and I'm really not sure why.

#333060 Homemades Picture Thread

Posted by roboman on 15 August 2013 - 01:03 AM in Homemades

Pumpbows/plusbows numbers 4, 5, and 6 out of 16.

The two pumpbows pictured are going to my aluminum supplier. One needs two holes to be countersinked, because I seem to have lost my countersink. Korned is receiving the plusbow once I make a priming handle for it.

#332810 Homemades Picture Thread

Posted by roboman on 09 August 2013 - 12:46 AM in Homemades

I tried vapor polishing a 2K turret.

I really like the results, and it prevents the o-rings from popping out of the groove.

#332705 Apocalypse 2013

Posted by roboman on 04 August 2013 - 10:55 PM in Nerf Wars

That was...wet. Very, very wet.

Pros:
-Seeing some awesome people again, and meeting others for the first time
-Freeze tag (and lots of it)
-VIP
-Nothing of mine broke, for once

Cons:
-The weather, as always
-Not having a change of shirt, shoes, or socks
-Pumpbows were not ready in time

I am still really sore from that. Definitely worth getting soaked in both rain and sweat for the experience, though. Hopefully, I'll be able to make it out there again next year, schedule permitting. I'd really rather not go through the whole "I'm going to build a whole bunch of pumpbows to fund my trip" thing again, so I need to figure out how to leave for school 2-ish weeks early next year.

#332440 Homemades Picture Thread

Posted by roboman on 29 July 2013 - 02:38 AM in Homemades

30 aluminum pumpbow sideplates. Cut free from the sheets, sanded, drilled, and wire brushed. I'll probably end up polishing them lightly to smooth out the surface a bit more, so you get the textured look of brushed metal without the roughness. The main issue will be removing the polishing compound from the surface, as I found out earlier today when I tried it on one plate. It ended up taking me about half an hour to scrub the rouge off of the plate.

My new wire wheel/buffer is in the background. I highly recommend them for anyone who does a lot of work with metal, since it takes care of deburring for you. That one is currently on sale at Harbor Freight for $40, and the brass wire wheel is another $5. Works great. The buffing wheel lets you have very high-polished surfaces if you use the right compound for the metal you're polishing.

#332439 S.U.M.D.A.G

Posted by roboman on 29 July 2013 - 01:42 AM in Nerf Wars

Not gonna be able to make it to this one. I leave for college on the 17th, so I guess it'll be a while before I can make it out to another SCUN war.

#332359 Homemades Picture Thread

Posted by roboman on 26 July 2013 - 05:21 PM in Homemades

Finally done with the sideplates. 8 hours of machining remaining for the other parts.

#332252 Homemades Picture Thread

Posted by roboman on 23 July 2013 - 03:15 PM in Homemades

I printed a bunch of turrets. (Yeah, that's a 3K one on top)

#332062 A Better Alternative to Spade Bits

Posted by roboman on 17 July 2013 - 10:18 PM in Darts and Barrels

Reduced-diameter shank drills like that are generally called Silver and Deming drills. Shars has them for super cheap, and they're single piece high speed steel. Link They've also got a bunch of other super inexpensive tools that work great if you're not in a production shop, like taps and stuff (and a huge selection of endmills and lathe cutters for those of you with fancier tools).

#331967 Homemades Picture Thread

Posted by roboman on 15 July 2013 - 06:39 PM in Homemades

Final revision of the printed 2K turret. Uses a 1/4"-20 bolt as the pin, which provides adjustable spring tension.

#331609 Modification and Paintjob Pictures

Posted by roboman on 06 July 2013 - 01:18 AM in Modifications

I fixed the notorious "black bar." First Maximizer of 4 to receive this treatment.

#331600 Armageddon XIV

Posted by roboman on 05 July 2013 - 11:43 PM in Nerf Wars

Out of curiosity, do glasses count for eye protection?

Typically, yes.

#331591 Modification and Paintjob Pictures

Posted by roboman on 05 July 2013 - 07:32 PM in Modifications

Rearloading 2K with transition barrels, an aluminum tank, and a 3D printed turret.

#331536 Homemades Picture Thread

Posted by roboman on 03 July 2013 - 01:43 PM in Homemades

Progress on the pumpbow prototype.

Posted Image

3D printed 2K turret. Seals great, fits 5/8" OD barrels, and is rearloading.

I'm probably gonna start selling them for $10.

#331466 possible balls for a homeade

Posted by roboman on 01 July 2013 - 07:35 PM in Darts and Barrels

I've seen a number of people use them. They work quite well in big airguns, particularly when you shotgun load a bunch of them in some PVC and cram darts between the balls. Makes for a really nice short-range spread. I'm pretty sure most people use them with 1.5" Sch. 40 PVC, which should give you a fairly tight fit.

#331360 Homemades Picture Thread

Posted by roboman on 28 June 2013 - 02:54 AM in Homemades

Bit of a preview of what's to come for Apoc. I'm making 4 variations on this (two traditional +bows and two pumpbows). 3D printed grip, pump handle, and stock plate.

#331277 Starting My Research Here

Posted by roboman on 25 June 2013 - 10:58 PM in Homemades

Roboman: Those look great! I assume those are metal, finished with some sort of white spray?

Shmmee: Of course, I'm building this for longevity as well as not-kill-people-with-plastic-shard'ity, hah In experimenting with the gun you showed me, did you ever try the hand tank/regulator combo? I'm curious what the pumps to shot ratio was.

Draconis: The regulator should prevent the inconsistency, more or less, I thought?

Once again, thanks for everyone that has put in their input, its been great!

They are polypropylene. Rated to 500 psi burst, 120 working. If you could somehow get one to fail, it would just tear, and would not send shrapnel anywhere. Super lightweight, too.

#331271 Starting My Research Here

Posted by roboman on 25 June 2013 - 07:25 PM in Homemades

I'm really excited to see these two posts, this gives me a great starting point. Thanks shmmee and rego for that, much appreciated.

A quick question - just because I'm not a fan of the bladder style tanks, do you think it would be possible use a rigid back pressure tank such as aluminum with a regulator attached? Or do you think it would be inefficient due to a long priming (or pumping) time and a low amount of cycles (shots fired)? If hand-pumping a rigid tank wouldn't work, I may have to consider using an air source such as a HPA tank.

These are awesome, and really cheap. They've got them in 3 sizes. They should work well for your purposes.

#331226 Homemades Picture Thread

Posted by roboman on 24 June 2013 - 12:56 PM in Homemades

The notorious black bar from a Maximizer. Now in aluminum! (Not completely done, still have to put a UHMW insert along the bottom so the plunger rod has a super smooth surface to slide on).

#331205 Nerf Elite Mega Centurion - Preview and Internals

Posted by roboman on 23 June 2013 - 10:04 PM in News

Ah, yeah, I see what you're saying. Didn't think about that issue. I wonder if a piece of e-tape or something slick slick on the inside would work, or if the o-ring wouldn't be able to deform around it... Otherwise, I'd imagine urethane resin or even some epoxy could act as a pretty good gap filler, since it dries smooth. I can totally understand why you don't wanna mess with it right now, though. I suppose we'll all see in the fall when they're released.

#331201 Nerf Elite Mega Centurion - Preview and Internals

Posted by roboman on 23 June 2013 - 09:32 PM in News

Interesting, thank you. It's not nearly as complicated as I expected. Hopefully, the PT is a common fractional inch measurement, so it can just be replaced with a piece of polycarb tube or something similar from McMaster. I'd imagine getting those air vents covered will help ranges quite a bit.

#331192 Nerf Elite Mega Centurion - Preview and Internals

Posted by roboman on 23 June 2013 - 06:30 PM in News

Any chance you could get some measurements of the plunger tube? ID would be particularly nice to know, if the whole thing isn't glued together, but if you could provide the OD and a rough estimate of the wall thickness, that could also work. I'm assuming, of course, that you've got a pair of calipers.

Also, could you provide internals pictures with everything in place, like the ones in the Internal Directory?

#331145 [WIP] Stampede ACB, the Arduino-powered Stampede ECS

Posted by roboman on 22 June 2013 - 01:17 PM in Modifications

I've done something similar with an arduino, using a push button as a mode switch of sorts. You're definitely going to want to set up that button as an interrupt, so that it stops the program and executes the section of code that changes the mode from safe to shoot. Otherwise, it'll be very hit-or-miss, so to speak, and may not reliably switch modes.

#331065 [WIP] Stampede ACB, the Arduino-powered Stampede ECS

Posted by roboman on 19 June 2013 - 11:16 PM in Modifications

You do have a motor controller for that thing, right (unless there's a built-in controller that the trigger switch just activates)? If there isn't one in there, the arduino can only source something like 20mA from the I/O pins, which is not nearly enough to drive that motor. You'll need a power transistor or a relay to drive that thing, most likely.

You might also want to consider a switch to detect the position of the plunger at the extremes of its travel, so you don't have to rely on timing to get the cycle correct.

#331010 Stretching Foam

Posted by roboman on 18 June 2013 - 12:37 PM in Darts and Barrels

Ya, I was thinking of a method similar to what Ryan mentioned it his slug making thread.

I used to use other barrels (mcmaster sch80, PETG, 9/16 brass) and they worked pretty well, but they were just expensive and all needed pvc couplers which were sometimes to big to use. I just like the cpvc because it is mad cheap and has its own couplers.

As for other foams, I really like foam that I can use a high-temp hot glue gun on just because it is much easier on the fingers and makes, in my opinion, better darts, and from What I hear mcmaster foam can't be used with a high temp hot glue guns.

I would really like people who actually stretch or have stretched their foam to respond(no offense roboman). And if anyone has different methods then what has been posted on Nerfhaven I would love to hear them.

Yeah, Sch40 PVC couplers can get annoying, I totally see where you're coming from there. If you're REALLY careful, you might be able to drill out some CPVC to accept PETG, so you can stick with CPVC couplers, but use a looser barrel material. Alternatively, you can get [mcm]1658T49{/mcm], which is compatible with CPVC couplers, but is aluminum and has the same ID as PETG. Not as cheap as CPVC, but certainly not super expensive.

Mcmaster foam can sort of be used with high-temp guns, but only if you move quickly. I have a dual-temp gun, and I switch back and forth somewhat frequently to maintain a temperature somewhere in between the two extremes, but that's obviously less than ideal.

I have actually stretched foam, as I said, but I've only used the hand-stretching method with limited success.

#330976 Stretching Foam

Posted by roboman on 17 June 2013 - 08:12 PM in Darts and Barrels

It really depends on the technique you use to stretch the foam. Ryan and Kane have had a great deal of success with the stretching frame they built for their pink foam, but that works particularly well for foam that's already cut into even segments, like theirs is. I'd imagine it would be a great deal more time consuming to have to do that to a whole spool of foam. I've seen some people hand-stretch their foam by tugging on shorter sections of it as they move down a length of foam. I've tried that, and it seemed to work, though it can be tough to achieve consistency while maintaining a good pace.

As for the big foam, it should work similarly, though you may need to pull a bit harder to get it to change diameters effectively.

You know that you can buy foam from other online suppliers, right? I usually get mine from Mcmaster, and while it's not necessarily the best out there, it works fine for me, and conveniently comes from the same place I order most other supplies for projects. It also tends to be a bit smaller than most other foam, for whatever reason (snug, but not particularly tight in CPVC-sized barrels). Of course, I can totally understand not wanting to throw out a bunch of foam, just because it barely doesn't fit.

You might consider switching to looser barrels on everything, though. That's usually significantly easier than shrinking your foam.

#330908 Tactical Rail Dimensions

Posted by roboman on 15 June 2013 - 03:10 PM in Homemades

All of the Nerf attachments rely on spring-loaded clips to hold their attachments to the rails. This removes the need for a truly standardized system, since their attachments can account for slight variations between blasters.

#330803 Is anyone interested in CAD drawings of stock parts?

Posted by roboman on 11 June 2013 - 10:54 PM in Homemades

My experience with digital calipers has been poor. I have a small one I need to return, it holds a zero so poorly, but I needed to do some metric measurements. I plan on getting a metric dial eventually. You can see this when you open and close them repeatedly, and they loose their zero. Even higher end ones do this, I've yet to see one that didn't, but I've limited exposure and probably haven't seen anyone spend enough money for a really reliable one.

STL files are the ones generally used by 3D printers. Also, most CAD programs don't do a whole lost with them without reprocessing them into their native format.

Another thing to note, but in passing, is that Nerf stuff is made overseas, and made to metric specs, 12mm instead of .5 inches, for example. The two don't match exactly, so if you're measuring in inches, you'll get odd numbers. If you try to round them, you'll be off by varying margins. Something to keep in mind, nice thing about Solidworks is it'll convert the two, so you can put a metric into an inch model and get the right dimension.

I've never had any issues with digital calipers of any brand - I've used both Starret and Harbor Freight (essentially the best of the best and the worst of the worst, respectively). Littlemachineshop.com has some nice intermediate models that work quite well and are priced reasonably.

True, but there are still relatively few printers in the community. I have access to a couple very high-end ones through school, as do a couple others, and 3 or 4 people have RepRap variants or Makerbots. Many, many more people have access to CAD, and .stl files import as triangle meshes into SolidWorks, which are a pain to edit or mate to. Most other CAD packages won't even let you open them (Inventor, for example, which is in widespread use because it's free to students). I'm not saying release a STEP instead of a .stl, I'm saying release a STEP in addition to the other formats, so that more people can use your files.

Unit conversions should not be a problem. When you start getting down to 4 places past the decimal, those measurements vary significantly with temperature if you're measuring correctly. A few thousandths is probably better than the tolerances present on the actual molded parts. However, you're not supposed to state a tolerance on the CAD model - it's supposed to be absolute. Drawing sheets state a tolerance because they're inspection tools and are supposed to tell an inspector how far off a part can be from the nominal dimension before it has to be rejected.

#330768 Is anyone interested in CAD drawings of stock parts?

Posted by roboman on 10 June 2013 - 09:26 PM in Homemades

Interesting. Are you sure the angles on the sides of the magazine are correct? They look a little steep to me, but I could be wrong. In any case, it looks nice, and you obviously put a lot of work into it. What version of SolidWorks are you using? I'm on 2012, and it's telling me these files are from a previous version.

Incidentally, STEP AP203 files may be more useful to a majority of the community. I vastly prefer .sldprt, because I'm SW certified and that's what I usually use for CAD, but most people here use free software. STEP is a universal format, and should be open-able by most major CAD packages.

#330758 Is anyone interested in CAD drawings of stock parts?

Posted by roboman on 10 June 2013 - 06:57 PM in Homemades

If you're not selling exact replicas of things copyrighted by a company, you're fine. How accurate are your models?

#330511 W.A.R.M.U.P.

Posted by roboman on 02 June 2013 - 10:46 PM in Nerf Wars

Oh if you bring the tanks we talked about, I can buy them there. If I can convince my buddy to come with, that is haha.

I'll see if I can have them ready by then.

#330502 W.A.R.M.U.P.

Posted by roboman on 02 June 2013 - 06:51 PM in Nerf Wars

I'll try to be at this one. I think my dad wants to have a barbeque or something, but I'll see if he can move it to the next day.

#330197 Electrical Problems

Posted by roboman on 24 May 2013 - 01:46 AM in Modifications

It's neither the switch nor the wire. 18ga wire can handle a LOT more current than you're ever gonna draw with a little motor like that. You're looking at 3 amps, 5 maximum, but likely even less than that. If the wire was too small, it would melt (I've done that), but the motor would turn very briefly. Since the motor appears to be the same as one on the compressor I took apart to mount on a robot earlier today, it's probably an RS-540 size motor. And, since it's a DC brushed motor, connecting it backwards will just make it spin the other way, which isn't an issue here.

18 gauge wire is rated for 16 amps, by the way. The only way you're hitting or exceeding that is if you're physically stalling the motor.

I've got that same pushbutton, and it can handle much more current than the package says. As it is, it's rated for 3A at 125V. That's plenty for this application - if that motor is drawing more than 3A for a significant period of time, something else is seriously wrong with your system.

The reason your wires melted when you tried it is because you shorted out your battery in the second setup. You basically created a very big fuse.

Now, there's a chance the compressor could be protected against reverse polarity with a diode of some sort. That's somewhat unlikely, but certainly a possibility. Try hooking red to red and black to black, like you're supposed to do anyways. Even if it doesn't fix your issue, it's a good habit to be in.

Check your compressor without the switch by touching the leads to the terminals in the battery connector. It doesn't matter how you hook it up, so long as you don't short out the battery. If it doesn't run like that, then you've either got mechanical problems or just a bad compressor.

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