Machsupport Forum
General CNC Chat => Show"N"Tell ( What you have made with your CNC machine.) => Topic started by: RICH on December 13, 2009, 01:51:04 AM
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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
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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
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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
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I can see where a wire edm would come in handy for this job, but , sorry , don;t have one.
Ed
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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
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Rich ,
Since your bore size will be approx .14 , I wouldn't worry about the rifeling , since your not going to shoot it.
Ed
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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
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Hello Rich
look for button rifling
it might give you another option
Marcel Beaudry
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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
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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
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Marcel,
I am not that familar with the specifics of the button or the different techniques of using it. Some say the press rotates the button when pushed through and others say they let the barrel spin when the button is pulled.
I don't know if i can even make the button but i got time to find and research options. ???
All part of the hidden challenges in doing the model. Hmm...... like the 108 TPI threaded portion ( Think i will cheat on that one!). The cut depth is almost not practical. ;)
Currently getting rotarty indexer done for the lathe spindle. I got to admit that there is a learning curve associated with this one.
RICH
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Hello Rich
The button turns by itself ,it is like driving a spiral nail in wood .
there are sites on the internet that shows how to make miniature firearms
Marcel Beaudry
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Macrel,
Have a link to one that gets into the detail? I looked at some that show the finished work but none that i looked at gave very specific details on how they did some of the tasks.
RICH
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Rich
try this
http://www.firearmsid.com/A_bulletIDrifling.htm
http://bbs.homeshopmachinist.net/showthread.php?t=32026
http://www.airgundevelopment.com/rifling.html
http://www.huidesign.com/miniature/index.php?option=com_content&view=article&id=5&Itemid=15&lang=en
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Thanks Marcel, will do.
RICH
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Rich
I read of some person who use a reamer rounded the edges of cutting surface plunged it into the bore of the barrel and the result was the illusion that the bore was rifled
Marcel
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Hi All,
Times flies when your having fun. I said this would take time.
You need to do little things like detail out the parts, make stuff to do the work
( had to make a tail piece for the indexer), and develop the gcode. Plan out the machining.
The pic's give you an idea of what is involved and this is just a fraction of it all.
Contouring the barrel will take a lot of code and seperate operations, will all be done with one set up,
PITA, since there is not one straight line so to speak other than the bore!
RICH
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Wonderful project! I used to have a model 29 classic hunter, 8" full lug barrel and unfluted cylinder, delicious fun and a great way to turn railway sleepers into firewood.
Ideas for the barrel: Use a section of .177 airgun barrel? Or use a bit of it for a guide to gradually scrape out grooves? A spring loaded cutter at the tip of the rifling tool would be easy enough to make, and would just wear a groove gradually. File the rifling out very carefully at the crown of the barrel to make it look deeper, if you need it, and if you can find a file that small :)
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Hi All,
Time just flies when your having fun. I got "in the mood" to work on the magnum.
Like I said, need to reverse engineer the darn thing to get dimensions for the scaled model, so been working on the cylinder drawings.
Here's a shot of the ejector, was a PITA, but got it figured out and can generate code for test cutting......
RICH
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Yep, still experimenting some with the model. I decided that some of the pieces will be done on the mill using
3D CAM to generate the code. The attached pic shows the steps:
1- Create 3D model and export as a STL file
2- Import into Meshcam
3- Pic of all the pathing
4- Profile pathing
5-Pencil pathing
6-Parallel pathing
7- Simulating the gcode
8- Run the file in Mach Mill
Now all i need to do is buy / find a bunch of 1/32" endmills as the ones i have won't fit the high speed spindle.
This piece is small as shown in my other posts. Cutting / forming the barrel will be much easier using 3D work.
Additionally it will help a lot on trigger and hammer programming. Especially true when you need to checker the
hammer as hand coding of it would be a PITA. New learning curve....just having fun when I am in the mood.
Maybe i better extend this project another 6 months at the current rate i am going! ;)
RICH
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It'll all be worth it when its done. :D
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Hey Ed,
I'm starting to like this machining with no shop cleaning to do when your done. I think they call it "arm chair machinist". ;D Guess it's time to find the test material and try out some of the 3D cutting.
Here is a look at the top of half of the barrel. I will probably try it a few different ways. Funny thing about the barrel is that other than the top of the bridge / ramp there is not a straight / non tapered line on it. Realy suck's to model it....... :)
RICH
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Rich. Lookin good, gotta give you credit, a full size is a bitch, you know what I mean.
Bigger would be easier...lol
Keep it up bud.
Ed
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Still fooling with the software to fine tune the machining. The attached pic shows the barrel partially machined.
To cheap to buy machinable wax, have Delrin pieces, but, a friend told me to try a cutting board and that's what i used for testing
the machine paths. 3 bucks for a 12 x 12 x 1/2" thick board. The stuff machines great and to dimension.
MODIFIED: The cutting board material seems to have a "grain" depending on what part of the board it came from.
You don't realize size until you hold it in you hand. I still need to add some contour machining since what is shown was only two sided and the piece
will need to be machined on all four sides or even additional angles.
RICH
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I was asked how long it takes to machine the barrel and said I would post some info here.
In a way it's a loaded question. One must realize that it will be machined in Al and then done in SS.
To machine the barrel to a fine tolerance / finish you need to adjust the cutting stepover. The piece is totaly tapered
except for the front sight and top ramp. Time is dependant on feedrate and the number of moves but also on appropriate feeds for the cutter.
IE; ROUGH: 1/8" ball mill / four flute / at 12000 - 18000 RPM and max depth at .050" and leave say max
.010" for a finish cut......will be about 6 -7 hours for the roughing.
The finish cuts will be at least twice that...so another 14 hours.
Then comes some detail work with a 1/64 end mill and smaller cutter. So another 3 or 4 hours.
So the total comes to about 25 hours of machine time. I want to make more than one as trying to put the engraving
on the sides of the barrel should be an interesting challenge. Add it all up.....think i will change how long this model is going to take. ;)
RICH
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Most don't realize how much precision machining goes into a revolver, or any other gun for that matter, but scaling down is another ball game.
Your doing good Rich, take your time and don't mess it up..LOL.
Ed
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I will not be using ammo made in certain parts of the world. Had to post as it's a S&W 44 MAG...... ???
RICH
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Nuttin' a lil bita duct tape caint fix.
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WOW that must have hurt
Marcel
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Perhaps you'd be better off using the Classic Hunter barrel with the full lug underneath, you'd have something to grip onto at least. I had a (blued) 29 classic hunter, it was an awesome old hogleg and great fun to shoot with full power train-stopper loads. Details aside, awesome project ... tiny stuff like this is very demanding work.
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Rich,
Looking at the grain structure of that magnum - is it usual for S & W to use a casting for the chamber ?
Tweakie.
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Tweakie,
I don't know how it is manufactured and have never seen a cylinder blowout like the one posted. I have shot thousands of hot loaded rounds
over the years with mine. Fortunately it was not mine. Some 20 years ago there were a batch of 44's which had bad cylinders and owners were informered.
I had one of them, it was stolen, and wish the low life a gratifying experience. >:D
My model will only use ammo manufactured by me, but then, it will won't be live. ;)
RICH
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Tweakie,
I am almost sure that is not a casting, it probably looks like that because of the failure mode, brittle fracture can look like that.
Sure glad I wasn't holding something like that it when it went off.
Arnie
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You'r probably right Arnie, it's difficult to see from the picture.
Tweakie.
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Back at it when time is available. I modified / improved the Atlas mill so it could reliably do 3D machining.
The engraving machine I used is limited in feedrate and 4-5 hour test runs is just not something that could be tolerated.
So attached are pics of a test done at 45 IPM. Took just 35 minutes to do, thus big decrease in milling time and quality is
good. An end mill was used but a ball mill will be used latter on for a better suface finish. Since there are places on the
barrel ie; top ramp and sides of the ramp that require a mattered or lined finish i wanted to see what the sharp end mill would
do.
Attached a few pic's of half the barrel showing machining steps and magnified view of both contoured and smooth
machining.
RICH
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Any updates? :)
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Yes and no.......
Reworked the Atlas mill's axes and now have zero backlash along with a very accurate Z axis. So now I can mill to the desired tolerances at a higher rate of speed which really reduces the time for machining required profiles. There are some things that need to be made which are a real PITA and takes time.
In the mean time ........just punching holes in little targets with the attached instead of finishing the barrel started in the picture.
What can i say....get back into it this fall. ;)
RICH
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Any ideas on how to do this easily? Maybe it's more of a CAD question.
I need to machine checkering into the the concave portion of this piece. The concave is first machined and then i would like to follow up with milling in the checkering. The cutting tool may only scribe in the lines since the depth will be in the order of .006" or so.
So the gcode produced will just provide pathing that follows the concave surface / base lines of the triangles. Easy to do if i wanted to keep the pathing running perpendicular to the axis of the surface. But that would look dumb! The pathing needs to follow the suface on a 30-60 angle to the suface as shown in the pic.
Any thoughts or simple way to put the lines into the surface of the solid surface so i could have CAM generate the code?
Guess you could slice the section into about 30 pieces and put 60 Gcodes together but that would be a PITA.
RICH
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Post the cad file and I or someone will generate the CAM profile
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The file is a .stl so you need to change the extension from dxf to stl.
You can assume that a point tool will be used thus the diameter is .001" or it can be any diameter but the center of it follows the path.
Depth of cut into the convex surface is .006" with .008" spacing.
Thanks,
RICH
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Will this work?
clamp part @ 40 degrees
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Thanks,
I assume that you are meaning to glamp the part so that the suface is perpendicular to the vertical tool.
It will work and will test the code out.
I have been playing around in Autocad 3D, real PITA to place the checkering just so if one dosen't want to rotate the part.
Meshcam is used to provide pathing to radius the left side, and then once that is done and without moving the piece, the right side
where the checkering will be placed is machined to a concave face. This is done with an 1/8" RN end mill. Then without moving the piece a point tool is used to scribe in the checkering. Need to remove the bulk as the darn point tool will blunt out or break in a heart beat...
In addition to the button release also need to do checkering on the trigger and grips which are not even modeled yet. Figured i would start with something easy ...HA HA!
RICH
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If it was a surface model, I think it would be easier to create the hatching pattern.
And yes clamp the part at a 40 degree angle so you expose the concave recess vertically up.
Most of these patterns are stamped or pressed in production.
Think Rhino surface modeling would be the way to go. Then project or wrap a line to a surface so you can machine/drive a cutter to it.
Then on the trigger you could cut perpendicular to the surface, and rotate the part on the 4th axis in a temporary fixture.
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Rich, I looked at the cylinder release on a 625, I believe it is the same frame, the checkering on mine s 90 degree and the concave is a 1/2" radius. If I wanted to model it in 1/3 scale I would make a sawblade with a tooth radius of .166 and stone the edge to the checkering angle. After finishing the shape with a .3125 mill, orient the release for the checkering angle and incremental feed to the depth in X, then Z down and do it again. The depth of cut might need to be adjusted, but the lower half would be a mirror of the upper half with less X as the tool left the horizontal centerline.
Anyway, neat project.
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Thanks sandcrab,
That's another way of dong it and the concave on mine is also 1/2" R. I'm trying make all the parts without any manual machining.
Just part of the challenge and forces one to explore. I have hand checkered manny hand grips and rifle stocks but plan on doing the trigger and grip checkering with CNC. I know for a fact that my checkering tools are not going to be work when the spacing is only .013" or less.
Still have a few things I want to try. Good thing is that the piece is small ...can make it from 3/8" dia round / about 1/8" deep
and a piece of round 12" long provides for a lot of cheap scrap pieces. ;)
RICH
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Wanted to try out some code so attached are a few pic's. Was curious as to how the mill would do. Cut the profile of the release button by mistake at 30 IPM instead of 3 ....before I
had a chance to blink ;) it was done. ::) Need to play around with the 3d code as I am not happy with the surface finish in some spots.
RICH
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One piece down and a bunch to go. One would think that all would be easy but between the code modifications and my
high speed spindle requiring a new collet it just takes a little longer than I thought. So used the slow speed of the mill to do the piece.
Surface finish suffers greatly but at least it's easy now to duplicate the part. Holding a thou and will be interesting to see how parts fit later.
Here are a few pic's.
RICH
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Nice work there, Rich-
Dave