[nitetrane98]

What type of tool is used for cutting the fine serrations on the top of a slide?
I could have sworn that I saw something like that on the Brownell site but can't seem to find it now. I'm thinking something along the lines of a slitting tool with edges ground to a bevel. I even thought of a boring bar type arrangement for super fine threads. I doubt the factory took umpteen passes but that would be no problem for just one slide. One guy said he had used a tap with 3 sides ground off in a pinch. A cheap suggestion will be appreciated. Seems like anything to do with a milling machine is pricey. Kinda makes you appreciate why machine work is priced the way it is.

[jmorris]

I knew one fellow that used a tap with all but one flute ground off as a start then cleaned up with a checkering file afterwards.

[krs]

You can get slitting blades with assorted angles in Brownell's, or you used to could. I'm sure they're still available in the supply houses if not. Those could be stacked, and all that was needed was to setup the slide on it's side. Best by far to do the entire cut with one pass.

If you've got a horizontal mill, or a 90 degree fixture for a vertical mill the job can be done much nicer with a cutter made for doing it. This takes scrounging through all of those machine tool catalogs and sites you keep getting. :)

Pretty sure that all of the nice work we see these days with patterns is done in a CNC milling center. They do magic that used to take hours, sweat, and tears.

[nitetrane98]

I am very fortunate to have a friend who has all of the machines you mentioned. I've found that are several methods to skin this cat. Slitter saw, 60 deg double angle cutter, and thread mill. I'm shooting for 40 lpi and the smallest biggest lpi threadmill I can find is 32 lpi so that's out. EGW has the slitter saw I need. MSC has DA cutters for half the price of the slitter.
Actually my friend is not a machinist just owns the shop and hires contract labor to set up and run his CNC's. So I guess I need to actually talk to one of his guys. I just never show up with a hand full of gimme and a mouth full of much obliged. I'll buy the tools I need for the job.
While we're talking about machining, did anybody not sleep through trigonometry? I'm trying to figure out the depth of cut to have 40lpi on a .400 flat with the lines having a sharp edge.
I know that 40lpi = one line every .025". If you bisect the cut you'll have a 30-60-90 triangle. So I'll know three angles and one side length, .0125. My depth of cut will be the other leg. I know it has to do with sines and co-sines but it was soooo long ago. My trig teacher was right, I will have to know this some day. Anybody?
Maybe I'd better make another thread.

[Riss]

I would think that a horizontal mill with a gear cutting blade might be the best method to make the cuts.

[MetalMan52]

From the info you supplied, I believe the depth of cut would be .0217.

a=.bxTanA where "a" is the vertical line bisecting your 60 deg angle
and "b" is one half of your .025 spacing
a=.0125xTan 60
a=.0125x1.732
a=.02165
a=.0217 (rounded off)

I hope that helps.
Pat

[krs]

Nitetrane,

You didn't say, but if it's your intention to mill a rounded slide flat on top for the serrations you'll likely get just the one go at serrating before the metal remaining above the lugs is so thin as to risk a broken slide. Off the top of my head it seems to me that the minimum is .055". Some of the slides out there won't give much room for a retry if your first cut is not to your liking.

Just something else to think about...

[nitetrane98]

Metalman,Thank you for the confirmation. I came up .216 and change too. I remembered there was something cool about a 30-60-90. triangle. If you know the short leg, A, the hypotenuse is 2A and the long leg is A x sq root of 3.

[nitetrane98]

KRS, fortunately I have an old de-milled FN 35 slide to practice on. I'm hoping to get about a .400 flat. That's my next geometry problem. Determining the radius of the slide and how deep I have to go to get a .400 wide flat.

I hate waiting on stuff. Haven't got my project gun from UPS or my slide through snail mail yet. So all I can do is plan and try to beg measurements off of folks.

[krs]

It's all good.

I only wish I'd taken more advantage of the low price mass availability of surplus parts when I was spending my time shooting bullseye and doing simple accurizing of my 1911 and those of my friends. At the time 1911s could be bought whole for very little money and excessed parts were selling for amounts like slides for $1.25, internal parts for $.75 in little ads in the back of Mechanix Illustrated magazine and the like.

I could have socked away a lifetime's worth of practice fodder. Nobody wanted the stuff very much.

[Jerry Keefer]

Nitetrane;
I don't do much 40 line work, but 30 line is .025 deep, so I'd say metalman is on the money...
Get an MSC catalog and look up Scientific Cutters. They 're carbide; a little pricey, but they are the best I've ever used.. very tough and durable..
Concentricity is perfect... great tools..
Good luck
Jerry

[krs]

x1 on carbide cutters. Nitetrane.

They definitely cost more but they will cut the hardened steel of most slides as if you were working in mild steel.

HSS cutters, or most of the tinned low carbide content cutters will frustrate you and you could end up buying enough of them, depending on the job, to have paid for the good stuff in the first place.

48 lpi showed up quickly for me, Nitrane, so your 40 is likely available in MSC too. I've got a 4-40 hand tap for something that came up though I remember it as slow to arrive years ago. http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=2663828&PMT4NO=57310158

Scientific Cutters better be good...considering :)