Chassis Build

jbolt

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This will be a build log for a tactical rifle chassis build. I figure since most of the manufacturing will be done on my CNC converted PM-932 I would post it in the CNC forum.

This is the CAD model I did in Solidworks. The chassis is loosely based on the Remington MSR. This is setup for a Rem 700 short action receiver.

JTAC-7000.png
JTAC-7000 Folded.png

I started with the easiest parts, the butt pad mount and slide.

The mount has ops on both sides so those were done in the vise. The perimeter was done by bolting it to a fixture held in the vise. The slide was drilled then bolted on the same fixture to do the perimeter and dovetail.

Tool paths in HSM Express.
Butt Pad Mount Tool Paths Small.png

Completed slide on fixture.
20160821_102425.png 20160821_102436.png

Completed mount and slide.
20160821_102829.png 20160821_102910.png 20160821_103637.png

The parts get more complicated from here so figuring out the work holding will be a challenge.
 
ooh neat looking, is this an "only for me" project or will you eventually make the file avail? :)
 
ooh neat looking, is this an "only for me" project or will you eventually make the file avail? :)
We'll see how it comes out first. :cautious: This is the 5th revision just in CAD. The final version may have some changes depending on how the parts come out or difficulty in machining.
 
I got the stock pivot block done today. I tried to take a time laps video but the lighting on the mill washes out the image and the flood coolant doesn't help. I'll try with the lights off on the next part.

I had a couple of hiccups. When I first designed the part I had the corner screw holes and counter bores too close to the edge. I moved them in but did not catch that the 1/4" spot drill would rub the side so it left a mark. The other issue was I made the rough stock a little too large in one direction and it cut one of the round overs a little too deep. Those are minor blemishes that will be hidden in the pivot well of the stock plus I will be painting everything so it can be fixed without remaking the part.

The part took 11 different tools over 5 separate setups. Total machining time was about 50 minutes including setup changes.

Part in CAD, with tool paths and finished.
Pivot1.png Pivot2.png IMG_0002.JPG
 
AWESOME!!! My Kid is going to flip. He's a few years away from this level of competence but hopes to be able to do things like this. What material are you using for the parts? Mix of metals? Alu... any Alloys or Titanium (teasing) to come. Will be watching Sir!

Thanks for the build post.
JJ
 
Very nice looking. I watched a build before on a mosin nagant that looked incredible. I was wishing he would have released his plans but he didn't. I have a mosin that someone had cut down a bit and would have loved to make something like he did. I think your build will be even more intriguing to many. Good Luck with the build.
 
Thanks JJ & Bill!

Next part is the butt stock. 13 tools, 7 setups, 22 tool paths, plus 1 fixture. The first 5 setups were done in the vise including the top, front, rear, left and right sides. The last 2 setups were done on a fixture held in the vise. These were the right and left contours and corner rounding. The corner rounding was done in a 3D tool-path with a 3/16" ball end mill. The corner rounds took 21 passes to complete. The fixture was setup to be able to flip the part and use the same work offset. The part was held to the fixture with two 8-32 screws through the clearance holes in the part and a plate at the front that used the already drilled holes for mounting the pivot block. I still need to do the narrow slits in the top and rear but I need to get a smaller slitting blade and arbor. Overall I am very pleased with how this came out considering all the different setups and I managed not to to screw up a tool path.

Tooling

ButtStockTooling.png

CAD and CAM
ButtStockLeftCAD.png ButtStockLeftCAM.png ButtStockLeftonFixtureCAD.png ButtStockLeftonFixtureCAM.png ButtStockRightonFixtureCAM.png

Completed part
ButStockLeft.png

Completed part with Pivot block attached.
ButStockRightwPivot.png
 
Here is part 1 of several showing the machining of the butt stock. I'm still getting used to this camera. It seems to stop recording after 48 minutes and has to be restarted so I missed some operations. I'm no video editor so these are just the raw footage speed up 16x.

 
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