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Reciever bolt ramp cutting


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Getting some ideas on how to automate a process. See attached pics...

Right now these "ramps" (highlighted in red) are being done in a separate operation with a custom fixture on a bridgeport style machine. In the interest of improving quality, time, ect, I have been tasked with researching ways of automating this. Right now, much of the work on this receiver is already being done on a lathe (The barrel threads are right up above these ramps.) My initial thought is with a C axis lathe it should be possible to broach or scrape out these with something similar to a grooving tool.

 

So the process would be to go in with an endmill, remove the majority of the material, then go in with the groove tool, and scrape out the corners.

 

Thoughts?

 

 

 

post-5509-0-67134000-1455031635_thumb.jpg

post-5509-0-03779500-1455031636_thumb.jpg

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I've done stuff like this with a C axis. The trick is taking light cuts, but maintaining enough sfm to not have tool wear issues, but also not exceed the ability for C and Z to stay sync'd.

 

For this part it looks like you will need a custom tool. PH horn is awesome for stuff like this.

 

If you get a tool made with the same angle as your ramp, you should be able to make your lead in rad as well.

 

You will have a bit of a burr on your lead out, if you have an angled live holder you can get in there with a small carbide ballmill and take care of that.

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Put me down for EDM. A CAPABLE edm shop should be able to knock those out pretty quick with the right fixturing and equipment. Trust me, I'm all for doing things complete in the machine but in this case I think you will die on the cycle time and you will never get the quality quite where you want it to be.

 

Mike

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Problem with this is that it's not so easy to farm it out being an FFL item.

Whats FFL?

 

This seems one of those occasion  on which I would love to kick the designers behind.  I have always thought that any designer should do 2 years in machine shop before they design anything...

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yes farming it out is not gonna happen. As far as the design, those helix/ramps have been cut into bolt action receivers since the beginning of time. Probably with a similar fixture/jig that we currently use. And our sinker (which is where we have done them in the past) is already at capacity. And it does produce a much nicer part....at the cost of time. Which is why we are looking at an on the machine broach operation. Might be time to give the guys at PH Horn a call.....

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Whats FFL?

 

This seems one of those occasion  on which I would love to kick the designers behind.  I have always thought that any designer should do 2 years in machine shop before they design anything...

 

The feature in red is a very necessary feature for a manually cycled bolt.

 

The feature that is more a of a pain in the @ss are the raceways running down the length of the body.

 

More and more mfg's are going to receiver and bolt combos that allow the lugs to be smaller than the bolt diameter so they can just drill a hole straight through and not have to deal with broaching or wiring out the raceways.

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Being an old timer EDM guy I would think burn as well.  However.....................what if you changed your other operations and left  material on the opposite sides of where you want these to finish, then you would have some symmetry to work with and you could maybe wobble broach?  If not the wobble then at least you would have more stability I think and could get it done quicker.  Then you go back and remove what is already gone in the pics you posted.  Just a thought since you are trying to avoid burning.

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Is the bolt really a FFL item? I thought that would only be the receiver.

 

Mike

 

As pointed out, this is the receiver.

 

But it depends on the ATF classification for that particular firearm, it can vary, which is why you need to get the skinny from the atf first. It can be the bolt, receiver, frame, barrel etc

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Looks like a Remington 700, or 700 based action.  What about going in 5-axis with a ~.040" ball mill.  You aren't removing that much material and I don't think the 0.020" fillets would hurt anything.  If anything they would increase the fatigue life because that is a bad area to have sharp inside corners.

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  • 2 weeks later...

Its looking like some of the process changes (and geometry changes) are going to be going on a 5 axis. I believe the tapered ball is going to be a winner. Now to find a off the shelf tool....Tho the quantities are there for a custom :)

http://www.harveytool.com/prod/Browse-Our-Products/Application-Specific-Designs/Hard-Milling_184/Hard-Milling---Ball-Tapered-Neck_188.aspx

 

 

these work pretty good...

 

on a bar feed 5ax mill you could do those complete pretty quickly...i see a bumotec s191 in your future.

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That Harvey tool "should" get me pretty close. I am allowed a .01 fillet in the corner. Between that tool & one I found from Mitsubishi I should be able to get it done. The Mitsubishi's are nice but also $$$. Still cheaper than another setup...thanks for the find.

 

I need to get the min/max dimensions on the bolt, and see if a .015 fillet would be liveable. One less tool, and a stronger part. Then it comes down to if the customer can live with a bigger radius......

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That Harvey tool "should" get me pretty close. I am allowed a .01 fillet in the corner. Between that tool & one I found from Mitsubishi I should be able to get it done. The Mitsubishi's are nice but also $$$. Still cheaper than another setup...thanks for the find.

 

I need to get the min/max dimensions on the bolt, and see if a .015 fillet would be liveable. One less tool, and a stronger part. Then it comes down to if the customer can live with a bigger radius......

those mits mills come from japan... lead time is always an issue with them

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