MODEL 629 S&W MAGNUM

[RICH]

This project is going to take some time so you will be reading this thread over a year or two.
There are a lot of small challenges to make this working model to a scale of 1/3 size.
The pistol will be functional but not shootable. Estimate that it will take some 200 hours plus to do depending on how many cutters and jigs need to made. So yep, it will  a labor of love, patience, and just fun in the challenge.  I always wanted to do something like this every since my friend made a miniture flint lock rifle which shot BB's for his 5 year old.

The cnc equipment will be used a lot along with CAD, CopyCat, photOgrAphy, image manipulation and tricks yet to be created. The scope may never get done as the optics for it may not be possible.

Picture 1 gives a comparison of the size.  Picture 2 shows some real rough overall dimensions.
Picture 3 shows the internals of the revolver. The hammer shown in pic 3 will fit on the end of
a piece of rod a little bigger than 1/4" in diameter. Picture 4 shows a cad file for contouring of
the trigger along with the Gcode generated out of LazyCam and into MACH3 Mill. Figured i would start with something easy. The brutal part of this is that a jig will be made such that
the shear surface of the trigger can be done.

I will posting a lot of pictures, so follow along if you wish and coment as you like.

RICH

[RICH]

The trigger will need to accurately held in place when machined. The first thing required is making a jig and drilling some small holes. I made a sensitive drill press, but, it would be so much better to avoid multiple setups. Picture 5 shows my home built engraving / milling machine which is extremely accurate. since a lot the tolerances will be to a thou. It helps to have an extended eye relief microscope for this kind of work. The one shown is 30x and 9" eye relief. You need that for drilling small accurate holes.

To drill the holes i will be using an MPG to bring the Z axis down for drilling. The MPG  is adjusted for very fine touch / feel as you rotate it instead of calibrated positioning. So the first thing was to experiment and see how it all would work. Picture 6 shows drilling 0.020" holes into C/S. I could see the drill walking....it dosen't take much. Note that the difference in the sharpening of the drills between 6A & 6C. Never buy junk small drills in these sizes as your
wasting your money. Actually a home sharpened jewelers bit is much better.  The trick in drilling small holes is to spot mark the surface and then just let the drill do it's job of penetrating the surface a few thou. Under the scope you can see any bending or run out of the drill bit. Pic 6B shows the bit just .005" deep and breaking the surface.

BTW, it helps to have a nice smooth surface. The drilling was done at 30,000 RPM  and to a 3/8" depth. Picture 6D shows the fit of the 0.0205" diameter pin, it's perpendicular to the surface and a hair is shown for comaprison.The center to center distance of the holes measured to with in a thou of required spacing.

A jig will be made which duplicates the frame mounted such that the trigger can be mounted and the shear surfaces hand done. ( that's how i used to do Ruger Blackhawk trigger jobs).

The pictures are what i see when using the the microscope.

Stay tuned for the fun,
RICH

[RICH]

Time for a little engraving testing. Pic 7 shows the CAD drawing imported into LazyCam.
Pic 8 shows the gcode file in Mach3 Mill.  Notice how the text was done to minimize
the amount of gcode and z axis moves. All curved surfaces are arcs which connect to lines.
You need to make sure you draw accurately and connect all lines and points since this will
provide a nice clean import into LazyCam.

Picture 9 shows size comparison to the original on the revlover.
Picture 10 shows the results of using different tools and depth of cut.
A sharp point  was used for 10B and depth was 0.002" giving a  line width of 0.003".
A small ball ended cutter was used for 10C and to 0.004" depth giving a line width of 0.009".
The text is actually distinct in 10C as the picture doesn't do it justice. Polishing post engraving,
can easily remove the engraving so need to be somewhere between the two.

RICH

[edvaness]

I can see where a wire edm would come in handy for this job, but , sorry , don;t have one.

Ed

[RICH]

Yes, they can do some neat and accurate work.

I am thinking about how to do the barrel rifling at the small scale. I am hoping i can do a long lead thread and
kind of line bore it with a special cutter on the lathe. The manual way way is painfull and don't feel like making the jigs to do it. But that is a long way off.

RICH
 

[edvaness]

Rich ,

Since your bore size will be approx .14 , I wouldn't worry about the rifeling , since your not going to shoot it.

Ed

[RICH]

Nahhhh.....,
Got to do it, ED. My buddy, a long time ago, made his 50 cal flint lock, hand drilled and rifled it. Do you know how lond it takes to drill a 48" long piece of metal with a hand operated drill? Good grief i was down his basement doing some of the rifling and talk about a boring job. stroke...stroke ....stroke ......for ever!
RICH

[marcel beaudry]

Hello Rich

look for button rifling

it might give you another option

Marcel Beaudry

[RICH]

Thanks for the suggestion. You still need to twist the cutter as it goes down the barrel. The groove will be about .003" deep. That's a realy hard push!

If i can get the lathe spindle down to about 5 rpm i can fix the barrel to the carrage  ( instead of line boring something i will be scribbing a wide line ) and mabe use a G32 command to send the carriage down the lathe bed at 90 or 100 ipm. That gives  a 1 in 18" twist approx.

 I would do about .001" cut per pass ( or less ). So three passes per groove and there are 5 grooves. After passes for groove one are done, i would index the cutter or barrel 72 degrees and do the next groove.

Sounds  a little wild, but if it doesn't test out then i will make a jig and hand do it. The jig  only needs to be some 8" long. ( the jig and reamer for the 50 cal rifle took up 12 linear feet).

RICH

[marcel beaudry]

Hello Rich

No the button as the same helix angle as your original barrel ,if you can have access to a press you can push the button trough the bore and it automaticaly creates the spiral.

Google rifling button

Marcel Beaudry