The Questions Thread.

Use a Dremel. Easier and cleaner and easier to clean up, you don't have to sand half an inch off because you dented the shit out of it when you cut it.

Small hobby hacksaw, or a heated hobby knife.

Where can I get a tap for plastics, PVC and such, machine screws to match, all that. And how much, roughly?

eBay or online is one of your better bets for taps unless you like being gouged on prices. As an amateur machinist, one of my favourite stops is http://www.ctctools.biz/

As for screws, if you can't find it in Bunnings or other hardware stores locally either http://australia.rs-online.com/web/home.html or http://au.element14.com/ will work for large quantities. Just don't expect to buy only 10 screws or something. Note that RS have taps as well. Good quality stuff, but the prices are pretty high.

Thanks for that, man, but it's all too complicated for today. I think I want about a 3mm tap, with 1mm pitch. And screws to match. Now, please let them fall into my lap (: hahaa. I'll figure it out.

Metric screws are easy to work out. Description is generally M3x0.5. First number (3) means that it's nominally 3 mm wide (actual width is minus a bit for clearance and fitting into the relevant tapped hole), the second number (0.5) is the pitch.

In your case, I've never seen a M3x1 screw. Why that pitch? Here's a list of the standard sizes:

http://www.tribology-abc.com/calculators/metric-iso.htm

Man, I'm studying automotive and mechanics, I've seem so many different kinds of fasteners.. The screws in stock blasters have a 1mm pitch. I think they're probably 3mm wide. Just figured that'd work best.

Those would be self-tapping screws, the threads are thin and spaced widely so that material that's displaced isn't compressed as much as if you tried to put a normal screw in there. Manufacturing wise it's easier as well since they don't need to either mold the threads in or have another machine set up for tapping all the holes.

Suspect they're not metric either, but I'm not sure on that.

I'm currently using a 8-32 tapping bit utilising 5/32"x25mm nut/bolt combo.

Ohh, right. The pitch is dead on a millimetre, think they'd be made in Asia which utilizes metric.

Okay, what would I do if having a nut on the other end isn't an option? Building a home made. Would I be better off using self tappers? And just drill the appropriate size hole?

Asia may indeed be metric, but the design is probably done in the US. Ehh, could be either.

What's the material and how thick? I personally just drill and tap anything that's plastic or metal, but that's because I already have the taps I need. If it's only for a few holes and plastic, self-tappers might not be a bad idea, but more than that and buying a tap might be useful.

It's a full blaster, about.. 14 Joins, 28 screws. Made out of PVC, so about 1 - 1.5mm thickness, x2 is 3mm all up for each join. Tapping sounds like the way to go.. I need it to be very stable, so strong screws. While still being possible to dismantle it for maintenance.

Best screws for this job and a tap to suit? Keep in mind, I'm hoping to not break the surface on the inside, or only minimally. Countersunk screws would be good, for a smoother finish, but not mandatory.

Bugger, that's thin...

This for the plunger or something? Uhh... my first recommendation would be to try finding some thicker material.

The problem with the material being so thin and not breaking through to the other side is that at the bottom of the threaded section you're going to have a cone cut out where the drill bit runs through. E.g. if you want to have an M3x0.5 screw you'll need a 2.5 mm hole before tapping. Say you have a 118 deg drill point, then if I'm calculating it right the cone will already be 0.75 mm deep. If I'm reading you right, each wall being 1-1.5 mm, so you've already decreased your thread engagement on the inner wall by half.

If you drill right through then you won't have that problem, but there's still not much engagement for each wall and you may still have a problem with the screw just slipping out of the inner wall and tearing out the threads.

If you really want to use screws, you may be able to get away with M2 or M3 screws, drill right through and then file/sand the screws down so that they don't protrude.

I was just thinking the same thing, about drilling straight through and sanding or whatever, the screw down. Looks like the only way to go. Keep in mind that the PVC fits into the joints already, very tightly. The screws are just to hold it there.

M2 sounds a little small, so it'd be M3, but with the pitch of .5mm, isn't the a little fine for plastic? Would have thought it'd need to be a bit more coarse.

How much am I looking at for fifty screws and a tap to suit them? Would I be able to purchase these from Nuts and Bolts, Coventry Fasteners? Is there somewhere I could get them cheaper?

I'd probably gravitate towards M3 screws as well, but for walls this thin, if you use a coarser pitch you run into engagement issues. Say we take an M3x1.5 screw. For 1.5 mm thick material you've got 1 turn of the thread going through it. That gives us one full thread of plastic holding the screw in. At the start of that plastic thread it's very thin, then it gets thicker as you progress around the thread. But because the material is so thin, but the time you've gotten half way around that turn it'll start to thin out again. Summing it up, the average thickness of the PVC around the circumference will be ~0.75 mm (probably a tiny bit under) but along half of the thread it gets very very thin, culminating in a point which actually has no PVC holding the screw in place. A wider pitch will result in more of the screw's circumference having no plastic holding it in place.

If we go back to our finer M3x0.5 screw we have 3 turns. Subtract half gives us 2.5 turns worth of plastic holding it in. It's a smaller diameter screw so the screw is naturally a bit weaker, but of the material that you do have it's more evenly spread out around the circumference of the screw. Average thickness of the plastic holding the screw in at a point around the circumference will still be ~0.75 mm, but variation in thickness is much less. I think at minimum you'll have 0.5 mm holding it in place, but I've got a headache so that might not be entirely right. Might be 0.6mm?

It's all a balancing game, too coarse a thread and you'll have bugger all holding it in, too fine a thread and you'll have what's essentially a nail. If it was thicker you're definitely right, I'd be advocating coarser threads, but for walls this thin a finer pitch seems more appropriate.

Dunno if I'm explaining it right, diagrams really help. Try reading this while you're looking at a screw from the side, it may help.

Either of the two stores you mentioned should have at least the screws, but I'm not sure about cheaper. RS (which I linked to you above) has a bag of 100 6 mm long M3 screws for under $10. Taps, all I can really say is to look around. I haven't needed to look for individual taps since I got a large set of them.

random guy wrote:What can I use to cut PETG. I heard from someone that you can use a hobby knife. Should I use that or something else?

A hobby knife WILL work, especially if you have far too much time and petg. Considering time, effort and frustration, it's probably not the best choice.

Considering what the others said, I actually really enjoy using my handy little pocket knife for working with plastics and marking metals. It's quiet, and if you slip it punishes the workman instead of the workpiece. [/romantic modding drivel]

Righto, that sounds alright. Yeah, I'm understanding what you're trying to say. Too small a pitch and the thread won't have anything to hold, too big and there won't be enough thread to hold the plastic.

What do I have to pay for postage on those screws? And do I need a credit card?

I'm on my phone, I don't have a computer, so it's a pain to look at big websites, unless you can give me a direct link to what I'm looking for, lol.

From RS, delivery is free. Options for payment are either a credit card or a trade account.

http://australia.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0553841

Right, that's good. Except that I own no credit card. A trade account is something I assume trade store would have? Doesn't help me much, either. Crap, lol.

Yeah, trade accounts are generally for business. If you've got a Paypal account then maybe you could find some on eBay, but if you've got neither then I don't really have any online places to recommend.

Mozart wrote:Right, that's good. Except that I own no credit card.

I come across plenty of people who make remarks that can't buy stuff online because they don't have a credit card.

Unless your area has an extremely limited choice of banks available, there a few major banks that offer debit cards, which have the same functions as a credit card, but uses your own funds and you don't have to go through the hassle of filling in forms about your income and credit rating.

I don't want a credit card. It's an unnecessary part of my life. Debit cards cost, you have to pay fees on them, which I don't find the need to.

I have PayPal, may look into eBay, but I think I'll be able to get screws locally, self tappers work pretty well.

I remember xoenz showed me this thing when I had business with him.

You can buy pre-paid Mastercards in Woolies or Coles. You only pay for that certain value, once it's gone, it's gone. No fees or anything like that.

Ok so assuming everything goes according to plan I should be getting a shiny new CWC longshot in the mail, and I've always fancied the idea of having a single shot under barrel shotgun. I've only got very limited experience with airguns and longshots, so I thought it would be wise to get some advice on dimensions. Probably leaning towards airgun rather than a simple spring ejection party popper method.

Any thoughts? Suggestions?

4B man. Pretty pricey for an undergun. Dunno what you're going to do about a shell, I don't imagine you're rolling in cash, although you may be. Buy that poly-carb undergun system off Coop772, it's on his website for $90.

Mate, I'd go for a BBUMB for an air tank. They're pretty easily expanded, and will cost less than half of what a 4B tank will.

Yeah, fully agree! Didn't think of one of those, as I've never owned one, lol.

Guys Im in the middle of reinforcing a Longshot boltsled and Im using these methods:

Epoxy putty in groove / alu bracket over the top and will be using the 'U' wire reinforcement and have ran into a small problem.

I've found that where the sled sits in the track, the under bit of the 'U' wire hits on the track guide especially on the blank half of the LS (opposite of trigger side) **PICTURED**

On the trigger half of the shell I cut away about 5mm of the track guide so that the sled would go fully back in the cocked position and accept the 'U'

I would like to know if anyone else who have used the wire method encountered such problem and what did you use to rectify it?

I personally was thinking to hack away along the track guide, length of the red 'L' (refer to pic) so it will accept the 'U' wire sliding along...

Any thoughts?



No WIRE:



Yes WIRE:

@Royal 86 - don't hack at the track. Sand down the epoxy adhesive/coat hanger so that it doesn't sit proud of the sled.

For future reference, you should bend over the little tabs of the alu brackets at the point. Refer to oznerfnerd's installation vid on ebay if what I'm saying doesn't make sense.

Hope that helps.

Cheers,

Yeah sweet, understood mate, just watched that vid on eBay and I see what you mean about the tabs.

After I attached the alu brackets and saw the sled (where the tabs bend over slightly) I thought I was too keen on the sanding down of the epoxy but I must of been mistaken.

Will note for future reference.

Cheers

@mozart & clunk, canceled... I can't bring myself to risk ruining that paintjob. guess i'll just have to get a drop holster so I can grab a quick sidearm for those russians with their pesky rush tactics...

@Royal86 - no problems mate, I've found that I need to sand down the coat-hanger most of the time. I've actually gone to using a smaller gauge wire, with no issues.

One thing I have noticed, is it does catch on the orange wings from where the dart stop pops up. I've cut them off on my latest LS, and have had no further issues.

@mister_elliott - I'm going to start on an under-slung shotty for the LS at some stage haha
Still testing your LS at the moment, range is good, but it's pretty hungry - been eating a fair few darts. Should hopefully have it sorted by the weekend.

Cheers,

Thinking that a minimised tetra strike might make for an appropriate shotty attachment, and i'm possibly back in the game! Looking at an internals pic i reckon mounting the forward section on the side of a primary, with a twisted up guitar string for a ghetto trigger. Under $20?? Can't go wrong!

mister_elliott wrote:Thinking that a minimised tetra strike might make for an appropriate shotty attachment, and i'm possibly back in the game! Looking at an internals pic i reckon mounting the forward section on the side of a primary, with a twisted up guitar string for a ghetto trigger. Under $20?? Can't go wrong!

I was looking at a single hornet tank in a housing, shortened pump, with a 4-barrel shotgun attachment. Still in development phase. Your LShot is completed too, by the way.

So I've got this Nerf Spectre sitting in a Layby bin at a Target, waiting for me to pay it off. My plan is to integrate a 2k into it. Can I be bothered?