1911 Handgun Slide Machining Hood clearance
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  1. #1
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    Default 1911 Handgun Slide Machining Hood clearance

    Hello all,

    I am looking for some tooling advise from the community.

    As an Aerospace cnc job shop owner and firearm enthusiast, I have always wanted to produce a line of 1911 handguns. Well, the time has come and I have started a company called Sbardella Arms. We are currently tooling up a Matsuura MC800-VF with 4th axis to machine the slides from 4140 forgings. I have been running some setup pieces and have been getting some encouraging results, but the barrel hood clearance cuts and the locking lug cuts are giving me some chatter issues. Basically, I have to reach down almost 5" with a slot mill to make the cuts. I knew this would be the hardest part of the job, so I called Iscar and they recommended one of there multimaster tools, 0.618" diameter x 0.118" width, three flute with 3/8" carbide shank. Well, running test cuts this tool is not going to be rigid enough. They recommended 741 RPM, 1.1" FPM and 0.02" radial DOC, it sounded terrible and I'm supprised the tool didn't break. I used override to try to dial the RPM's down and the feed up a bit, but nothing seemed to work. That 3/8" shank 5" long is just not rigid enough.

    So, iscar makes another shank that is 1/2" that tappers to 3/8" at the end and it looks like I will just barely have the clearance. Also, they have some 6 flute cutter heads that I might try.

    But, before I invest in more expensive tooling that "might work", I thought I would ask if anyone has any advise? Anyone have experience machining 1911 slides? I have heard that some companies use a detachable support arm and just have M0's in the program to install/uninstall the arm for each slide, but that seems very sketchy to me and I would like to avoid that method. Any help would be appreciated!

    -Neil
    Attached Thumbnails Attached Thumbnails e2dfea53-cf7b-4e87-9cda-52d0700177c9.jpg   5b67b0a0-a969-460a-9059-3b374f6f3a7a.jpg   5807e39f-9f8b-4360-b003-c16473c3eb5d.jpg  

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    The WWII era tooling to make those cuts was essentially a form tool (think long endmill with thinned sections between cuts) and a backing plate that pushed on the thinned sections from the 'bottom' of the slide.

    I used to have a picture of it, if I find it I'll post.

    GsT

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    Here is a picture from an article I found:

    slide-cutting.jpg

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    I'm not sure what your programming capabilities are, but I would be tempted to surface those slots with a flat endmill from the open part of the slide by rotating the A axis. I'm not sure how hard you could push the endmill, but it's basically free tooling... harder programming.

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    Neil S has the solution. Do it the way John B designed it to be done. He was brilliant and designed the product as well as the tooling to make the product.

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    If it could be done in 1911 it should not be hard to do 110 years later.

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    I too have often wondered how best to do those cuts with todays tooling and not a job specific machine. Most of the home shop guys I have seen do it, use as big an endmill as they can from the end and then grind to just enough clearance to make the cut. So same basic tool like you have just the shank is almost as big as the cutter.

    Only other thought I had before was a sinker edm.

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    Quote Originally Posted by Neil S. View Post
    Hello all,

    I am looking for some tooling advise from the community.

    As an Aerospace cnc job shop owner and firearm enthusiast, I have always wanted to produce a line of 1911 handguns. Well, the time has come and I have started a company called Sbardella Arms. We are currently tooling up a Matsuura MC800-VF with 4th axis to machine the slides from 4140 forgings. I have been running some setup pieces and have been getting some encouraging results, but the barrel hood clearance cuts and the locking lug cuts are giving me some chatter issues. Basically, I have to reach down almost 5" with a slot mill to make the cuts. I knew this would be the hardest part of the job, so I called Iscar and they recommended one of there multimaster tools, 0.618" diameter x 0.118" width, three flute with 3/8" carbide shank. Well, running test cuts this tool is not going to be rigid enough. They recommended 741 RPM, 1.1" FPM and 0.02" radial DOC, it sounded terrible and I'm supprised the tool didn't break. I used override to try to dial the RPM's down and the feed up a bit, but nothing seemed to work. That 3/8" shank 5" long is just not rigid enough.

    So, iscar makes another shank that is 1/2" that tappers to 3/8" at the end and it looks like I will just barely have the clearance. Also, they have some 6 flute cutter heads that I might try.

    But, before I invest in more expensive tooling that "might work", I thought I would ask if anyone has any advise? Anyone have experience machining 1911 slides? I have heard that some companies use a detachable support arm and just have M0's in the program to install/uninstall the arm for each slide, but that seems very sketchy to me and I would like to avoid that method. Any help would be appreciated!

    -Neil
    I use that 3/8 carbide iscar tool all the time and really like it. It works really well, but your probably asking too much in your case. I dont think there is anything more rigid then a solid carbide shank in that size. Too small for dampened tools as far as i know. The half inch tapered shank will be much better if you can fit it. Thats assuming its still carbide, forget about steel shanks. Tungaloy makes the same style tool as well, may want to look at their shank sizes as well.

    One thing that will make a huge difference is a thinner tool. Try a 1/16th (or smaller) wide insert with multiple depths. Also I would try much less then 0.02 radial. That will still probably work out to fairly high engagement angle in a tight bore. Even if you can manage to just take off 2-3 thou at a time, and crank the feed, it still wont take long to do that one groove.

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    Quote Originally Posted by moonlight machine View Post
    If it could be done in 1911 it should not be hard to do 110 years later.
    That's what I figured, that there was some special tool developed by now that can do it without a support arm. And their may be, but I have not been able to find it. I have spoke with rep's from Iscar, Kennametal and sandvik and no luck. The Iscar rep recommended the 1/2" shank tool but he's not guaranteeing that it will work.

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    It's a nice tool for sure, Iscar makes great stuff. They do have some thinner cutting heads that we could try, but another factor is machine time. There are actually two grooves for the barrel locking lugs, and a much larger relief cut for the barrel hood. I would like to keep total machine time below 1 1/2 hours, so for now we are going to try the support arm tactic. One of my guys started fabricating it today, hopefully finish tomorrow. We will use a piece of bronze for the bearing surface that will run on the tool shank. It will be a little awkward to install/uninstall, but it should make the tool 1000 times more rigid allowing us to complete the cuts quickly. The downside is that it makes it 1000 times easier to crash the machine...4acf34d4-d9d5-4479-8248-7b0784e31d4f-1-.jpgnew.jpg
    Attached Thumbnails Attached Thumbnails ad8e5774-3761-4ed8-ac29-7844a1bf348b-1-.jpg  

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    Quote Originally Posted by mmurray70 View Post
    One thing that will make a huge difference is a thinner tool. Try a 1/16th (or smaller) wide insert with multiple depths. Also I would try much less then 0.02 radial. That will still probably work out to fairly high engagement angle in a tight bore. Even if you can manage to just take off 2-3 thou at a time, and crank the feed, it still wont take long to do that one groove.
    That sounds worth trying. They’ve got some mighty thin inserts.

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    Hey Neil. Looks like you have come quite a ways since the Tree.
    Keep at it.
    Adam

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    I'd sure like to see more of the gun guys posting up their tricks. Pretty cool stuff.

    Not much of a gun guy, but I do own one handgun and it's a series 70 1911.

    I shot a 1911 built in 1918 that had less than 10 rounds fired in it's life. Still in the original box. Perfect like the day it was made.

    I got to empty twin belt fed .50's with full ammo cans and tracers just after sunset in the middle of the pacific ocean once.

    If I could choose one of those things to do again it would be shooting and admiring that 1911.

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    Check with the guys at GW Schulz (gws tool group)... I know they make a lot of firearm specific tooling. They may have something for your application. Contact page here: Contact - GWS Tool Group

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    Quote Originally Posted by ARB View Post
    Hey Neil. Looks like you have come quite a ways since the Tree.
    Keep at it.
    Adam
    Thanks Adam, hope you are doing well. We actually just got our AS9100+ISO9001 certificate, which is a big step for us.

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    In my opinion we need to figure out to how to add a pneumatic cylinder to the fixture with some kind of nylatron end that dampens that monstrous long shaft which activates after the Z to depth move occurs and pushes against the shank of that tool at a specific PSI while the feed/cutting move is occurring and then retracts when its done cutting. If all goes well, you might be bale to get a tool that cuts both lugs at once. What I see in the OP's pics is kinda scary.

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    What about using a single point cutter in a boring setup? PH Horn may have something?

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