alberic6 Posted January 15, 2016 Share Posted January 15, 2016 Hi guys, I'm a machinist, working on building myself a 2011 longslide. Frame is a 2011 with the long dust cover, and the slide is an STI Unique 6". Since I've already read War & Peace, I want to do some lightening cuts on the slide to get the cycle time up. I've got a full CNC machine shop to back me up, so I can do anything I want. The question is: what do I want? In reading various forums, I've seen references to slide lightening cuts causing stress cracks. But very few of them have any references to which *types* of cuts, where, causing what sorts of cracks in what areas. So I'm asking here, as I figure you guys put enough cycles on your weapons that if anybody'd seen cracked slides, it'd be here. The only specific reference I've seen was to the Brazos 'angled holes' cuts "always cracking". (Thread on 1911.com) That one really puzzles me, since they're *round*. If there was one cut I'd expect to be least likely to cause a stress riser, that'd be it. Anybody seen that failure? Has anybody seen any *other* failures from slide lightening? Care to share? Many thanks, Brian Link to comment Share on other sites More sharing options...
MrPostman Posted January 15, 2016 Share Posted January 15, 2016 I have seen some stress cracks in the ejection port area and at the front of the slide where the rail is tapered. The ejection port ones are not usually caused be lightening since you generally do not want to cut weight out of that area. Now the other location is where the frame rails hit at the end of the stroke so it takes a beating so would stay clear of that area. Also try not to cut into the rail area of the slide, this will weaken it considerably and cause cracks down the road. The ones I have cut were cut on top, tri topped or slotted length wise on the sides. These are in my opinion the safest cut options. Of course if you can do the work yourself then it really isn't that big of a deal, when it cracks just buy another slide, cut and fit it. Link to comment Share on other sites More sharing options...
jcc7x7 Posted January 15, 2016 Share Posted January 15, 2016 Generally guys want their 6" slides the weight of a 5" So tri top it and you'll get your weight off evenly distributed. W/o much chance of slide failure Link to comment Share on other sites More sharing options...
Ultimo-Hombre Posted January 15, 2016 Share Posted January 15, 2016 Brian, I have put a fair share of rounds thru slides with Brazos cuts. Never any issues. I moved to open and had a local smith build my gun. We started with a blank and I learned s bit from him in designing my cuts. Sounds like you are well aware of how cut shape effects metal stress. It would seem that location of the cut has more impact on crack potential than the shape. Staying well above the rails is wise. Do you have a specific weight goal? I ask because I thought I needed a lighter slide to speed up cycle time to get better performance. I discovered that I shot better with and preferred the heavier slide. If you could do some comparisons shooting others guns at different slide weights you could avoid the " lighter is always better" trap I fell into. I bet a tri topped 6" with just a few simple louver cuts would be awesome. Have fun! Link to comment Share on other sites More sharing options...
lcs Posted January 15, 2016 Share Posted January 15, 2016 Generally guys want their 6" slides the weight of a 5" So tri top it and you'll get your weight off evenly distributed. W/o much chance of slide failure You must be extremely careful when tri-topping. The ejection port will crack!!!!!!!!!! Best not to tri-top or shave it like your face.. How do I know they crack at the ejection ports....$800 for new slide fitting and different cuts. it happens pretty quick too. Link to comment Share on other sites More sharing options...
alberic6 Posted January 15, 2016 Author Share Posted January 15, 2016 Hi guys, Thanks for the replies. In looking at the thing, with the *loooooooong* dustcover, and the 6" slide, it looks like a brick. So what I'm leaning towards is to cut the dust cover back a bit, (but not as far as a stock 5") then do a 'hi-power' cut on the nose. Flat top it, and serrate the flat top, then ball mill the upper shoulders, like a tri-top, but as concave grooves. (Skipping the ejection port area.) It's already destined for a Bo-Mar rear. Given where the STI rails are, there's a fair space in the front of the slide that never sees contact. I was thinking of doing some angled louver cuts thru the slide that punch thru up high, but then come out to about .020" deep grooves as they cross over the rail, and mate up with matching grooves on the dustcover. If I leave the long (hidden) plunger tunnel more-or-less intact, I figure that'll give me enough support to offset whatever grooves I put thru the slide above that area. They'd all have radiused ends. Sound like a plan? Thanks, Brian PS--> After I wrote my first question, I found a reference to a big long discussion that happened here about cracked slides, about 2010 or so. But I can't find it by searching the forum. Anybody remember it, and have any idea what keywords to look for? I've tried all the obvious ones. Link to comment Share on other sites More sharing options...
MrPostman Posted January 16, 2016 Share Posted January 16, 2016 Sounds good to me. SVI does the grooves where the meet the dust cover and it is a good look. Just remember that you are ahead of the game with your shop so you can try different cuts with much less money invested than most people. I love being able to do this stuff in my shop, I don't have the cnc yet but I will sometime in the future. Right now my mill with DRO fits the bill nicely. Good luck with your build Link to comment Share on other sites More sharing options...
alberic6 Posted January 16, 2016 Author Share Posted January 16, 2016 Hi Guys, Whatever I do, the grooves will be curved, and there will be a depth sweep. Because I can. I'm toying with the idea of doing the grooves as "S" shapes, just 'cause. Things a CNC can do that a Bridgeport can't. (easily) On the other hand, I'm going to have the thing ion bonded when I'm done, so I'd just as soon it not self destruct after I paid for *that*. (Yeah, it's turning into that kind of a project.) Wish me luck. I'll post pictures when (if) I ever get it done. Figure 6(ish) months. I'm going to get it shooting as a flattop with no major cuts, and see how I like it, and then decide how serious to get about lightening cuts from there. Many thanks. Brian. Link to comment Share on other sites More sharing options...
BeerBaron Posted January 16, 2016 Share Posted January 16, 2016 Look up pictures of guns with a 'butler cut' as far as the nose treatment goes. It's a nice way to get away from the brick look of a full dustccover/unique slide combo. Link to comment Share on other sites More sharing options...
Climbhard Posted February 17, 2016 Share Posted February 17, 2016 Ive seen several tri-topped around the ejection port Link to comment Share on other sites More sharing options...
Nickb45 Posted February 17, 2016 Share Posted February 17, 2016 I'm building a 6" short dust cover gun, I'm planning on just a tri top. I like the clean/simple look. I will compare it to a buddies gun (same 6" short dust cover, bushing barrel and steel grip but some ports and stuff in the slide). Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
silver star Posted April 12, 2018 Share Posted April 12, 2018 PICTURES !? Link to comment Share on other sites More sharing options...
Broncman Posted April 12, 2018 Share Posted April 12, 2018 I love the look of a trip top that stops short of the ejection port and the muzzle end of the slide. Somewhere there is a thread about taking weight off the front of the slide vs rear vs evenly front/back and how it makes the gun react to recoil/recovery. And yea, we want pics as you go! Link to comment Share on other sites More sharing options...
Powder Finger Posted April 12, 2018 Share Posted April 12, 2018 3 hours ago, Broncman said: I love the look of a trip top that stops short of the ejection port and the muzzle end of the slide. Somewhere there is a thread about taking weight off the front of the slide vs rear vs evenly front/back and how it makes the gun react to recoil/recovery. And yea, we want pics as you go! CHA-LEE search I think Link to comment Share on other sites More sharing options...
Powder Finger Posted April 12, 2018 Share Posted April 12, 2018 I think this is it Link to comment Share on other sites More sharing options...
SCTaylor Posted April 12, 2018 Share Posted April 12, 2018 OP was two years ago, last reply before today was also 2 years ago. The OP hasn't been on since October of '16. Link to comment Share on other sites More sharing options...
Scott Steele Posted April 12, 2018 Share Posted April 12, 2018 OP was two years ago, last reply before today was also 2 years ago. The OP hasn't been on since October of '16.I'd bet we don't get "pics".Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
alberic6 Posted April 13, 2018 Author Share Posted April 13, 2018 HI Scott. Never bet against the house. I haven't been on because I bought a business. Now I own the machine shop. Been a tad busy. So where it is right now, is as a working longslide, with a totally flat blank slide, a bomar rear sight, and a grooved flattop. It's been sitting like that since ?Christmas? '16 or so. (I also bought a friend's race gun, so it's not like I don't have 1911's to play with...) I've got a couple of different versions CAD'ded out, but I didn't really like any of them. I kept doing funny squiggly cutouts that moved in all three axes, just because I could, and none of them looked very good in simulation. Sometimes, just because you can, it doesn't mean you *should*. So I've been contemplating stress risers and workholding in my spare moments. I'm planning on getting back into it sometime soon. And I definitely appreciate the helpful comments from the first time around, they did (and do) influence my thinking. It's definitely going to have a butler cut front end, and some work done that transitions between slide and dustcover, but I had to get it shooting before I knew what the alignment was for that. Regards, Brian Link to comment Share on other sites More sharing options...
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