So, I don't even know where to start honestly. I have no knowledge of fluid dynamics what so ever. So that's where you come in... Hopefully...

First, If I'm I was directed to the wrong place, STOP READING NOW. I'll feel less embarassed and really apreciate it.

I play paintball in National and International circuits.

I shoot WDP Angel G7 paint markers.

I'd like to design a bolt weighing under 10 grams made of Ertalyte TX. (Industry standard for marker bolts is delrin of some sort)

But anyways. I need some help designing a bolt with MINIMUM WEIGHT and MAXIMUM FLOW RATE. I'm paying for the material and have full access to a shop. www.GenPrec.com My father is the Senior Mold Designer. I'd ask for his help but despite my success in the sport, he fails to awknowledge it or me participating in it. (Yeah other issues to be dealt with... lol)

So basically I can post up any kind of measurments, photographs, etc etc etc of anything you mite need that could help me. And again. I really apreciate it.

Thanks, Kevin

Ertalyte® TX Information: Ertalyte® TX rod for machining high-wear-resistant parts is an unreinforced semi-crystalline thermoplastic polyester (PET-P) that has a solid lubricant filler. The material has excellent performance in both high-pressure and high-velocity conditions, and is ideally suited for applications involving soft metal and plastic mating surfaces.

Key properties of Ertalyte TX, are its high strength and stiffness, high wear-resistance, very good dimensional stability, high creep resistance and very good chemical resistance. This combination of properties make it an ideal material for machining bushings and bearings that require no startup or running lubrication.

Ertalyte TX has FDA and USDA compliance and is ideal for applications in food packaging and processing equipment.

Ertalyte TX stock shapes are made using proprietary resins produced by Quadrant. Quadrant's Ertalyte TX shapes offer dimensional stability, wear resistance, and low-friction characteristics superior to those properties of competitive filled polyethylene terephthalate polymers. Excellent replacement for Delrin AF.

Also, I realize I know nothing about this field. Which is why I'm really grasping for any help I can get here so please don't mock me if this is the wrong place or shoot down the idea. I'm following through regardless because the stock bolts are shit. I'm not in this to produce something I can market and sell. I need a better bolt. that's it. At my level of competition, the little things count. The difference between a consistant shooting gun that does or does not break paint matter. With events worldwide and sponsors shelling out thousands of dollars. It matters. Paintball is the second largest extreme sport in the country. With over 15 million participants nationwide, maybe even you or your kids.

I really do apreciate any help you can offer, ever referances.

Thanks again, Kevin

What is 'a bolt'??

can i post pictures on this forum?

ttp://img160.imageshack.us/img160/9900/impulse7bu.jpg

wow i had this whole diagram drawn out with _, -, >,^, O, and various other symbols. i click preview and it doesnt work. and i cant post pictures. so theres a link lol

basicallt the bolt is attatched to a hammer which is attatched to a pneumatic ram pushing the bolt and hammer forward and back

when the hammer goes all the way forward it strikes a valve piece

this piece slides forward to open the valve and allow air from a reservoir to pass through the valve, into the bolt. (there is a hole in the bolt that lines up with the valve when the bolt is forward...)

the air passes through the bolt and propels the paintball out the barrel

link didnt work...

heres a good one

http://img160.imageshack.us/my.php?image=impulse7bu.jpg

My only experience with paint balls has been on the receiving end. When I put up anti-Iraq-war signs before the invasion, the front of my house was shot up with paint balls and the signs with lead ones.

I'm sorry to hear that. Hunting is a sport and you can't stop people from using their guns to shoot other people just like in paintball you cant stop immature irresponsible kids from doing equally dumb things.

I don't especially see how it's applicable to my situation.

thanks for the help....

OK, using the coloured references, could you tell us where is the hammer, the paint etc. for someone like me who is not familiar with this stuff, what (where) is the piece you want redesigned?

ALAS! some help

thank you for the time and interest!

The bolt is what i want redesigned. it is light orange. the hammer is just below it and it is connected to the bolt by the Green bolt pin.

this isnt the same model gun as i have but its the best diagram i could find.

I want to redesign the bolt to have a better air passage and reduce the mass. so its lighter.

It seems that you have to change something related to the hole of the bolt or the gas you're using to give impulse to the paintball. Is it correct?

Regards

Renato.

i'm going to need you to be more specific. theeres teh hole at the end of the bolt where air is released ONTO the paintball and there is a hole in the middle of the bolt where air enters teh bolt.

i dont quite see how the type of gas will have an effect.

compressed air is used. the bolt cycles with approximatly 55psi of pressure and the gun operates around 270psi

Ok, I'm just speculating and trying to understand your problem better. Thus, let me try to guide you about some doubts I had after reading the first post

MINIMUM WEIGHT, Why? To keep the weight of gun low?!

MAXIMUM FLOW RATE, Why? To make the paintball reach longer distances?!

the less the bolt weighs, the more i can lower the LPR pressure (bolt cycling pressure) this will minimize the kick (recoil) and be more gentle on brittle paintballs (especially in the winter)

i'm told that a better flow rate will increase the velocity the paintballs are shot thus enabling me to lower the input pressure into the gun to make it more efficient. a better flow rate and better more even distribution of air over the ball will give it a better spin. and will shoot with a better trajectory greater accuracy, etc...

Ok, it's getting clearer...

MAXIMUM FLOW RATE without changing the air pressure. It could be reached changing the shape of the hole. I'm sure we have some specialists here that could give you a teach about jet flows and some related topics.

Another question:

Would the recoil be mainly due the hammer?

well the whole mass that is cycling is going to effect the recoil. this is the bolt the hammer and the ram shaft. i';m replacing the stainless steel hammer with a hammer made of the same bolt material Etralyte TX. this should help considerable. if all goes to plan the combined weight of the new bolt and the new hammer will be lighter than the stock steel hammer alone

yes that is the point.

the way most bolts are designed is its the normal shape of a bolt. then basically they drill a hole the length of it as the air passage and then they drill another hole in the side as the inlet to the air passage.. this provides a poor flow rate right? because though its pretty much unidirectional for the air to travel in only one direction. it isnt as smooth or efficient as it could be if it was a smooth curved roundedd air passage from the inlet to the end of the bolt.

Does the air passage have sharp edges? if so they have to be rounded. Anyway, do you have an iges file for the bolt? or could you provide a sectional view of the bolt as it is right now? please keep all proprietary details out, but the air passage has to be as exact as it is right now Cheers and be as Job

ummm. the air passage doesnt have sharp edges. i'm not trying to fix the one i've got i'm trying to redesign a better one.

i'm affraid i dont know what an "iges file" is

i just took these pics of the bolt to help you get an idea of what i mean. they took a mass (uncut undrilled bolt) and just basically drilled a hole in it....

http://img95.imageshack.us/my.php?image=hpim12323gp.jpg

http://img95.imageshack.us/my.php?image=hpim12330ck.jpg

http://img451.imageshack.us/my.php?i...pim12343qn.jpg

hope these help

and again thanks for your help everyone so far.

Firtly, you should have a computational model of this piece in order to make CFD simulations and study the efficiency of the new proposed design.

A IGES files is a file format widely used in the CAD/CAM/CAE worlds to store computational models.

Cheers

Renato.

I have no back ground or knowledge in mechanical engineering. My Father is a Senior Mold Engineeer at a company so he could probably do it for me on solid works. but if you read my first original post. he wont.

Not to be a slacker. but for such a small project i dont have the time or resources to learn what it would take to be able to compute calculate and research the best possible designs. I'm using common sense to kind of come up with the most efficienct way of getting the air form one end to the other.

so as far as computational models go. i dont know how to make one. i'd apreciate it if someone could. or could run it through a program to determine what would be good!