Gunsmithing CZ rimfire oversized bolt knob questions?

[BenY 2013]

So I am wanting to put a larger bolt knob on my CZ 452, would also like to do it for a few future 455s in the works. I want to do it all myself. I would prefer to mount it in a lathe if possible! I have a few ideas in the works but need time to test it out. I was hoping someone here could give me some pointers or ideas! I guess I could take the knob to a grinding wheel and then when its the right size thread it with a die. Like I said I would prefer the lathe as it is more precise and repeatable! Thanks guys!

Ben

 

[BenY 2013]

Anyone got ideas?

 

[Boltfluter]

I have done several to date on the mill. Very awkward to do to say the least. No two bolt handles are the same as far as the profile goes. I would head to the grinder and go for it. It may take a while as they are very tough. Good luck.

Regards, Paul

 

[AHPP]

Maybe something similar to the Savage bolt knob jig if you want to use a lathe. And yeah, I bet they're hard. Toolpost grinder or even a dremel clamped the the toolpost might help that. You could maybe even grind the thread with a profiled dremel cut off disc to make things extra complicated!

 

[cannoncrossfire]

I've done 30 or so CZ452 handles here in Australia, and they're hard bastards.
I linish/grind the ball into a shaft around 8mm dia, then carefully grab it in the lathe on that 8mm dia shaft, turn it carefully and 'true' the diameter to 6mm (put a little shoulder on it where the thread should finish), then linish the end that was in the lathe to match the perfectly machined diameter, put a slight taper on it, then run an M6 die over it to put a thread on it. I'll try supply some pics to make it clearer.

I tried making a jig to make it quicker, as the grinding/linishing is the real crap part of the job, It takes about 15-20mins with a 40grit belt to make a rough shaft to work with, making sure I dunk it in water to cool it off. Problem with the jig was that STILL each bolt handle is different and I have to end up ditching the jig because it won't make the thread centre on EVERY handle.

I can't produce them fast enough to keep up with demand, which sucks because there are heaps of people after them.

The knob I screw onto the handle is a CNC machined Aluminium knob, slightly smaller than your standard badger style knob (scaled down basically).

I should mention that because they're a cast handle, there are holes/pores/air pockets in the casting 99% of the time... You might see it in the first pic, I have to fill these holes with Silver Solder, re-linish/machine, then they're threaded.
The whole thing is blasted and Cerakoted/baked because the blueing is long gone by the end.

 

[BenY 2013]

Thank you sir!!! That is exactly what I was needing! I appreciate your help and those handles look really great!

 

[Nathan11B]

Might want to try short action customs.

 

[cannoncrossfire]

Thanks BenY, glad to help, hope it made it a bit easier/clearer so you know what steps are involved, and what the outcome can be. Feel free to ask more questions, or for any pics as I modify the handles pretty often - 10 or so ready for Cerakoting this weekend.
If you can, I usually prefer to thread up to a shoulder on the handle, so that the knob locks up against the shoulder on the handle nicely. I use loctite to keep the knob on, and this way i'm not worried about how long the thread is on the handle, or how deep the hole is in the handle (because it isn't relying on 'bottoming' in the hole).

 

[BenY 2013]

Thanks BenY, glad to help, hope it made it a bit easier/clearer so you know what steps are involved, and what the outcome can be. Feel free to ask more questions, or for any pics as I modify the handles pretty often - 10 or so ready for Cerakoting this weekend.
If you can, I usually prefer to thread up to a shoulder on the handle, so that the knob locks up against the shoulder on the handle nicely. I use loctite to keep the knob on, and this way i'm not worried about how long the thread is on the handle, or how deep the hole is in the handle (because it isn't relying on 'bottoming' in the hole).

Thank you for your help! I did this yesterday and was really pleased with the outcome! I did have a question though, do you have any way that can thread without cutting crooked or off center? Mine wasn't perfect, but I used some epoxy to blend in where it met and I think it'll be fine!

 

[cannoncrossfire]

Glad to hear you managed ok!
You do get a crooked thread occasionally, it's not easy. I do my best to line it up by eye when I start threading with the die, but if you find that the knob is crooked, a trick i've tried is to file the shoulder back only where it touches the screwed on knob, until when you screw the knob on it's even all the way around where the shoulder of the handle meets the knob.

Epoxy would work well too, just make sure it's not going to chip off easily.

Each bolt handle is a little different too, i've been able to use the jig I made for some of them, and this gets the threads perfectly full formed and parallel, but I do more by hand/eye versus in the jig.

 

[BenY 2013]

Thank you for the reply! I appreciate it very much! It's nice to have someone who does a lot of them not turn me down, like what happened in the past!

If it would be possible I'd love to see that jig if you can take a picture! No problem if you can not!

 

[Hooper]

So I am wanting to put a larger bolt knob on my CZ 452, would also like to do it for a few future 455s in the works. I want to do it all myself. I contacted 'hooper' here from the hide and asked if he would give me any helpful tips on how I could get it done. All he replied was "lol", not trying to bash him or his business, just hoping someone else here could help me out.

Ben

Use a Mill, make jigs, order custom tooling to allow cutting of hard stuff, break a few in the process learning what to do and not. You will appreciate it more if I do not give you the cliff notes.

LOL...

 

[BenY 2013]

Use a Mill, make jigs, order custom tooling to allow cutting of hard stuff, break a few in the process learning what to do and not. You will appreciate it more if I do not give you the cliff notes.

LOL...

I understand you not wanting to give out your notes about your process. I apologize if it seemed like I was bashing you as that was not the intent. I was really hoping to learn from someone has been doing it for much more time and does it very well, and I do understand you are running a business and can not tell all of your secrets. I apologize for my rash and childish comment.

Ben