Joined: May 09 2015 Location: United Kingdom Posts: 2
Posted: May 13 2015 at 9:04am | IP Logged
I need to make the knob/ball larger on my cz455 bolt handle.
I am in the UK and due to lack of facilties etc I have given up on trying to buy a larger knob and getting the handle stem threaded.
I think the only way I can make the ball larger is to cast over the original ball,using a mould.
I will have to use a resin of some sort.Can anyone tell me what I should use.the handle is blued steel so I would like a smooth dark finnish.
Joined: February 26 2013 Location: United States Posts: 4241
Posted: May 14 2015 at 11:07am | IP Logged
Why not use some 2-part epoxy, and get a good sized glob on it it. Let it set, and then sand it down smooth to the size you want. Then paint it.
If it comes off, chip all of it off, then roughen the bolt handle w/ sandpaper, & go it again.
Joined: July 16 2013 Posts: 944
Posted: May 14 2015 at 11:33am | IP Logged
As you're in the UK, have a look in Halfords or another motor factors, and look for a two part plastic welding kit. It is specifically designed for joining ABS type plastic fairing panels on motorcycles and hard ABS type car bumpers.
Roughen the surface of the bolt handle with a coarse wet and dry paper, and ensure it is degreased afterwards then mix a small amount of the two part plastic welding kit and apply it to the whole area in a thin layer.
Once this has cured, usually no more than ten minutes depending on temperature, then repeat the process building it up in layers until you achieve the desired size and shape, once you have the final shape you want then add a final layer with a small amount of black paint mixed in and apply that before covering it in cling film, or cellophane which will give a nice smooth finish.
Alternatively you could look for some Delrin rod or balls and drill and thread those.
Where about in the UK are you based? Most good engineering shops should be able to turn down the bolt handle and thread it for you, alternatively you can grind down the bolt head yourself using a 4 inch grinder and sanding disc to make it into a rounded rod, then run a suitable threading die down it to thread it yourself and then drill and tap your Delrin ball to suit or shape the Delrin rod to suit and drill and thread that.
You can run a 6mm dril through a small piece of Delrin bar, then put a long 6mm bolt through it and a nut to tighten up to form a spigot before putting it in an electric drill clamped to the table and use a rasp or sanding disc on a grinder to shape it, before final polishing with fine grade wet and dry, then remove the bolt and run a thread down the hole.
If you do that to start with and thread a blind hole you can use a piece of all thread with a nut to lock it and put that in a drill to turn it.
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