19 replies to this topic

[ChiliPepperFender]

I recently got a Crossbow from Mayhem(Thank you), and there is only one thing wrong with it. The plunger head broke off. I haven't seen anyone else have this problem. Does anyone know my best bet in connecting the two pieces back on? I was thinking glue, maybe gorrilla glue? I don't have any experience with epoxy or plumber's goop, but I know they're strong. Keep in mind, the glue has to be able to hold alot, i.e. when the spring is compressed over and over again. Here's a picture of what I'm talking about how it is broken.


Thanks in advanced for your help.

[bpso86]

Mine had the same part broken, and I can tell you that no glue will hold that type of joint over time. I think realistically the best bet for longevity would be to make your own plunger head out of washers and try to screw it in, but that front part is hard to work with. I actually cut off the front part for the dt3 arrow shooter and attached that to mine, except I haven't gotten around to reinforcing it with metal yet, so I can't tell you how well it's worked.

[ChiliPepperFender]

I'm still using the stock spring, I thought about making my own plunger but if possible I'd like to keep the stock one.

[Rover]

If you are intent on using the stock plunger, may I suggest attemping to create another plunger rod out of polycarbonate and then holding the stock head on with a some kind of fastening device?

Edited by Rover, 05 May 2008 - 07:45 PM.

[Cmdrmack]

I'd recommend screwing it in from the front, and then epoxy-ing the crap out of it, as it will probably have some exposed threads.

[ChiliPepperFender]

If you are intent on using the stock plunger, may I suggest attemping to create another plunger rod out of polycarbonate and then holding the stock head on with a some kind of fastening device?

I've never machined anything out of polycarbonate. I'll keep that in mind.

I'd recommend screwing it in from the front, and then epoxy-ing the crap out of it, as it will probably have some exposed threads.

What do you mean by screwing it in the front?

[Ccapogreca]

I'd recommend screwing it in from the front, and then epoxy-ing the crap out of it, as it will probably have some exposed threads.

Yeah, just do that, I've seen people drill theres in, with a right size screw, and they held perfectly well. I think.

[Ryan201821]

I can make you a custom plunger if you want. PM for details.

There is no real solution to fixing this. Anything will eventually break overtime causing frustration. A homemade plunger is your best bet.

[ChiliPepperFender]

I can make you a custom plunger if you want. PM for details.

There is no real solution to fixing this. Anything will eventually break overtime causing frustration. A homemade plunger is your best bet.

Thanks, I'll pm you.

[Galaxy613]

*nvm*

Edited by Galaxy613, 05 May 2008 - 08:54 PM.

[VACC]

Yeah, take the thing to your local hardware store and pick up a screw long and thin enough to drill from the tip of the head into the wider surface where the plunger head separated.

[ChiliPepperFender]

Thanks for the help everyone, I'll try that this week.

EDIT: After looking at the end of my plunger where there is no plunger head, it is extremely small, less than a quarter inch. I guess I'll have to find a small screw.

Edited by ChiliPepperFender, 05 May 2008 - 10:37 PM.

[Cannonball]

I dont think anyone has said this, but as for epoxy, I suggest Devcon Plastic welder. You will not be disappointed.

[ejrasmussen]

Epoxy Putty!

[ChiliPepperFender]

Epoxy Putty!

If adding a screw doesn't work out with the plunger head, does this sound sensable, to epoxy the plunger head to the plunger then add epoxy putty? Or would adding the putty do nothing? This is all of course, if the screw thing doesn't work out.

[OfAllTheNerf]

Putty is good or body with but isnt a terribly good adhesive. I would recommend fishin' glue, from what Ive experienced its damn strong.

[ompa]

I agree; the putty is great for filling space/providing support when the adhesive properties are secondary, from my experience, although FA may have more experience with the stuff.

I'd ask CS about types of plastic welder he'd recommend, as he seems to have experience in the area.

~ompa

[sam]

I would use a combination on things. First increase the area of which you can put a screw into by gluing some polycarbonate, or plastic of some sort right near the break on the plunger rod, maybe a half in strip on each side. Then wrap the newly thickened part of the plunger rod in some aluminum sheeting or something like that to reinforce it. Then use a long thin screw and put it all the way through the plunger head and into the thickened plunger plunger rod. Hopefully that made sense.

[Nonsense Man]

I think IPS weld on #3 or #4 would be you best bet here is a quote from Captain Slug's Machining Plastics thread. He also mentions other plastic glues on pg 3229. As other people have suggested I suggest finding a screw that will fit on the plunger head and running that through then using you plastic glue of choice and gluing that joint then get some aluminum sheet 8 by 12 (I think) sheet for around $5 and gluing (with your glue of choice) the aluminum in that area and along the hole plunger rod (if you want0 for maximum strength. Epoxy Putty isn't really made to be the main holding force of something under tension more as a extra measure (not a lot though).

IPS Weld-on #3 or #4: This is an extremely useful and effective plastic solvent that fuses ABS, Polycarbonate, and Acrylic together (in any pure combination of the three). Simple brush onto or apply to contact area with syringe then secure pieces together in the final form you want. #3 formula is slightly thicker and faster setting, while #4 is water-thin and sets more securely. #4 is recommended for anything you are trying to make air-tight because it's thin enough to use capillary action to fill all of the gaps between the sheets you are joining together. In order to join sheet edges securely and tightly make sure they are sanded to atleast 400grit level and are straight enough to make a scure bond. You do not have to apply any contact pressure to get a good chemical bond. Over application will lead to ugly, but working joints. Can be applied an reapplied as needed without complications.
It's a good idea to use this in a ventilated area, and while it will not adhere your skin to plastic it WILL create permanent fingerprints. This is a mildly toxic substances so excessive skin contact is not a good idea.
It with also work with butyrates and styrenes, but I have not tested it on polypropylene or polyethylene yet so you'll need to ask a plastics shop about compatability. I do know that it is completely incompatible with all PVC plastic blends so avoid buying ABS/PVC (Kydex T). ABS/PVC is a crappy plastic anyways. If you need a specific solvent for a material, check out the wide range of products available from IPS: http://www.ipscorp.com
Both #3 and #4 (and a whole host of other plastic adhesives) are available from McMaster (page 3229).
To apply Weld-on accurately and safely I recommend using 3ml luer-lock syringes with flexible PTFE tubing "needles".
These can be purchased from medical supply, or through industrial supply catalogs such as McMaster (part #s 7510A651 & 75175A691)

Edited by Nonsense Man, 06 May 2008 - 04:32 PM.

[The Crackerjack Man]

If you don't want to spend the money on a custom plunger, no offence to anyone who is trying to sell one to him or somthing along those lines, I think you should stick with the broken one. Put a nail or some sort of metal rod through the front, around where the old plunger used to be. And make sure its small enough that it won't hit the plunger tube, but big enough so it holds the spring back. Then make a custom plunger head out of some washers and O-rings, or just use the old one and lube it up.

Just a suggestion.