rattlesnake pens

[PenPauli]

I just made 2 rattlesnake slimlines. They came out extremely nice but when I went to install the transmissions both pens cracked. I'm so frustrated. The trannys slid in nice and straight but when I had to press it in just a little more the darn lower half cracked. Has anyone else had this problem before? I think as the tube in the lower half expanded from the pressure of the tranny it caused the crack. Oh well that is 2 nice rattlesnake pens I cannot sell. Any tips from anyone for future use. Thanks.

 

[ctubbs]

The casting over the skin is very thin by the time the skin is attached. Anything in the tube will cause the expansion to go critical and crack the PR.Just an idea.
Charles

 

[Drstrangefart]

You may be able to repair them with thin CA and Micromesh it back to a high polish. I've had to do that before, it ain't perfect, but it can make it sellable to someone on-the-spot that doesn't care about imperfections. Depends on if it just hairlined, or if it split and pulled away, I guess.

 

[thevillageworkshop]

Chamfer the tube before pressing in the tranny... this will take off the sharp edge.. sometimes brass shavings will follow the tranny into the tube taking up expansion space resulting in a cracked blank. Also make sure the inside of the tube has no glue residue, etc.....works much of the time, especially on acrylics, & casting resins.

 

[ctubbs]

For the 7mm tubes, find a 22 caliber brass cleaning brush at the local sporting goods store and clean the tube before assembly. That will make it easier.
Charles

 

[kenlicciardello]

+1 on what thevillageworkshop said. Sometimes the thing you are pressing in isn't exactly straight and it goes in at a slight angle. This extra pressure can cause the crack. Arizona Silhouette carries a chamferring tool for around $15 that works well.

 

[PenPauli]

Thanks for the info, I also wonder if it was the trannys I used. They were laying around and now that I think about it, they didn't have any grease or whatever it is that they come with on them. Oh well I'll make sure I clean the tubes out and chamfer them next time. Thanks again.

 

[MobilMan]

You can use your pocket knife to chamfer the ends of the tube & clean out any glue. A narrow blade used at a 45 deg. angle. Works as good as anything.

 

[seamus7227]

You know, when it comes to cleaning out the barrels, I use brass cleaning brushes that can be purchased at Harbor Freight. here is the link http://www.harborfreight.com/10-piece-tube-brush-kit-95947.html

What i do is get rid of the steel tube brushes and use the brass to clean out the brass tubes. works well for me anyway!

 

[islandturner]

Chamfer the tube before pressing in the tranny... this will take off the sharp edge.. sometimes brass shavings will follow the tranny into the tube taking up expansion space resulting in a cracked blank. Also make sure the inside of the tube has no glue residue, etc.....works much of the time, especially on acrylics, & casting resins.

I give slimline tubes a pretty good reaming with a chainsaw file just before assembly. I've had so many split, that I'd rather have them a bit too loose than too tight. A bit of locktite ensures a looser fit will stay put...

 

[bruce119]

They can be fixed. Don't use CA it may but most likely wont work. First off where did you get them more precisely where they made from Polyester resin. If you say where you got we can figure out if they are PR. I would bet there are since they cracked. What can be done is chip and or grind out the crack and recast with PR. I fix cracks frequently with excellent results PR adheres to it's self 100%.

Now to avoid it in the first place you do not want the brass tube to expand. If there is any glue in the tube or if you skew the part when pressing it will crack. also if the parts are tight and you fell you are putting on a little pressure in fact your better off grinding your parts NIB and final a bit then gluing them in with epoxy.Like others said with a slimline you are getting thin and PR is brittle. I had them crack with kits like Jr Gents best bet is to take a little off the part pressing in and glue epoxy you don't want the tube to expand very bad.

Good luck