• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.
[4]

Chassis Build

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

Sendit

Active Member
Active Member
Joined
Mar 21, 2016
Messages
95
Likes
57
#32
Hi Sendit, I'm not sure what you are asking?
Jbolt, sorry i was in a bit of a hurry when I typed my message. How did you go about modeling the pocket in the chassis for the receiver to sit in? How did you correct the rear tang area since it was off the first time? I'm trying to get a accurate model of a Remington 700 but I do not have the correct tooling just yet to be confident in my measurements
 

jbolt

Active User
H-M Supporter-Premium Member
Joined
Dec 3, 2013
Messages
1,226
Likes
1,010
#33
The inlay is straight forward with the receiver being round. The size of pockets for the trigger, safety & bolt release were done by measuring the receiver/trigger and also one of the Bell Carlson stocks I have. Since I am using a box magazine I just used the magazine dimensions with some clearance for fit and measured its location on how it fits against the receiver.

For the tang area the error was in my favor so material removal was necessary. The rear tang is not flat but has a slight radius to match a typical hunting style stock. I didn't bother with that since it is not important for this build.

I have not fully modeled the receiver. Because I am not trying to make a receiver all I need is the relevant dimensions to do the inlay.
 

jbolt

Active User
H-M Supporter-Premium Member
Joined
Dec 3, 2013
Messages
1,226
Likes
1,010
#34
I couldn't find a check valve locally that would work and it was a week lead time to order one so I rolled my own. Works great!. I posted a quick build thread on that if anyone is interested.

With the coolant system operational I was able to finish the last op on the barrel guard mount. The 2-1/2" flute 3/8" end mill chatters like crazy no matter what I try. Maybe solid carbide would be better but since this project is getting painted I can live with it. It just adds some handwork. The slots will be done on the 4th axis. The last photo is the fixture parts.

BarrelGuardMount08.png BarrelGuardMount09.png BarrelGuardMountFixture.png
 

vertcnc

Steel
Registered Member
Joined
Jun 4, 2013
Messages
28
Likes
15
#35
For those deep cuts I have used a reduced shank carbide end mill. Various sizes are available. I have used the 3/8" with the flute length of 5/8" and the shank is something like .370. It takes a few steps down for deep pockets or in your case, outside profile. Then a finish pass of .005 pretty much removes all tooling marks. Also make sure you only have the tool sticking out of the holder the min. required. I purchased these from Maritool in Woodale, IL (they have an online store.)
 

jbolt

Active User
H-M Supporter-Premium Member
Joined
Dec 3, 2013
Messages
1,226
Likes
1,010
#36
Thanks vertcnc. I figured there was something like that. I'm familiar with Maritool. Of course now I have done all the deep stuff on this project. :confused:
 

Silverbullet

Active Member
Active Member
Joined
May 4, 2015
Messages
2,428
Likes
1,108
#37
Watching for more very nice build. What's your finish weight target. About seven pounds I'm guessing.
 

jbolt

Active User
H-M Supporter-Premium Member
Joined
Dec 3, 2013
Messages
1,226
Likes
1,010
#39
A little more work completed. I got the 4th axis completed and running but the first motor I used was too long. I had to put a sorter stepper motor and coupler so it would clear the new enclosure so I could use the flood coolant. It also took a while to get the Mach3 post modified correctly for the 4th axis.

This is the vent slots on the barrel guard mount. To index in HSMWorks I had to create an individual tool path for each slot. That's just a matter of duplicating the first tool path and editing it for the correct orientation and contour of the next slot.

BGM07.png

I decided error on the side of caution and run a test part before committing the actual part to the last operation on the 4th axis which I am still getting used to. I turned a piece of stock the same diameter as the finished part and set the offsets for the actual part so if it was successful then the actual part can be ran with no other setup needed other than orientating the part in the 3-jaw.

Success! (and no the chuck key was not in during the machining)

BGM01.png

Here is the actual part mounted in the fixture in the 3-jaw ready to machine.

BGM02.png

Machining completed!

BGM03.png

That was the last operation for this part so it is now completed.

BGM04.png BGM05.png BGM06.png
 

jbolt

Active User
H-M Supporter-Premium Member
Joined
Dec 3, 2013
Messages
1,226
Likes
1,010
#41
Beautiful piece of machining!

Tom S.
Thanks Tom. There is definitely room for improvement. I'm still discovering the appropriate tools for certain jobs.

I desperately need to fix the backlash in the system that has creeped in over the last two years. Not so bad for one off parts but it really shows with the multi faced assemblies. The double ball nuts seem to be the way to go.
 

jbolt

Active User
H-M Supporter-Premium Member
Joined
Dec 3, 2013
Messages
1,226
Likes
1,010
#42
Well it was bound to happen sometime. I scrapped my first part. I started on the barrel guard and I think I was a little too optimistic about my setup.

Here is the CAD.

HG_07.png

Here is the guard modeled in the fixture.

HG_08.png

Here is the turned guard blank ready for machining.

HG_01.png

The guard is mounted between a plate that is attached to the rotary axis and a plug that rides on the tail stock taper. A threaded rod is between the plate and plug to hold the guard under compression. The guard at the plate end is tapered and is very thin. There was not enough surface area to properly grab the face of the plate.

HG_04.png

In addition my lead in speed was too fast, the lead length and lead radius were too small.

The end result.

HG_03.png

I remade the plug that is pressed into the plate with a larger OD that is a press fit into the guard. On the tail stock end I drilled out the center of the plug and made a Chicago bolt to go through the plug. The bolt head is counter-bored for the tail stock. This gives me greater clamping pressure.

HG_06.png

I also decided to not turn the OD and taper yet to leave a greater clamping surface.

Here is the revised fixture.

HG_05.png

Ready to try again as soon as I tweak some of the g-code.

HG_09.png
 

jbolt

Active User
H-M Supporter-Premium Member
Joined
Dec 3, 2013
Messages
1,226
Likes
1,010
#43
Things went pretty well today. I learned a few things but overall I'm happy with the result.

First op was to cut the flats on eight sides. I'm glad I modeled the fixture in solidworks. I caught a cut interference with the button head cap screws that hold the fixture to the rotary axis. I was able to change the lead out to avoid it.

HG_10.png

Next was drilling the holes.

HG_11.png

Next is milling the slots.

HG_12.png HG_13.png HG_14.png HG_15.png

Next is the chamfer on the slots. I was getting some chatter out at the tail-stock end. At first I thought it might be because as the slots were being cut the torsional rigidity was being compromised allowing that end to twist a little. Turned out the tail-stock was not tight. Oversight on my part.

HG_16.png HG_17.png HG_18.png

Final op on the 4th axis is the front contour. I couldn't figure out how to do this tool path in HSMWorks so I used Aspire for the CAM. I added some additional screws to keep the end plug from rotating in the part during cutting.

HG_20.png

Off to the lathe to turn the final OD and rear taper.

HG_23.png HG_24.png

Completed part ready for final deburing.

HG_25.png HG_26.png HG_27.png
 

TomS

Active User
H-M Supporter-Premium Member
Joined
May 20, 2013
Messages
1,485
Likes
465
#44
Things went pretty well today. I learned a few things but overall I'm happy with the result.

First op was to cut the flats on eight sides. I'm glad I modeled the fixture in solidworks. I caught a cut interference with the button head cap screws that hold the fixture to the rotary axis. I was able to change the lead out to avoid it.

View attachment 142418

Next was drilling the holes.

View attachment 142419

Next is milling the slots.

View attachment 142420 View attachment 142421 View attachment 142422 View attachment 142423

Next is the chamfer on the slots. I was getting some chatter out at the tail-stock end. At first I thought it might be because as the slots were being cut the torsional rigidity was being compromised allowing that end to twist a little. Turned out the tail-stock was not tight. Oversight on my part.

View attachment 142424 View attachment 142425 View attachment 142426

Final op on the 4th axis is the front contour. I couldn't figure out how to do this tool path in HSMWorks so I used Aspire for the CAM. I added some additional screws to keep the end plug from rotating in the part during cutting.

View attachment 142427

Off to the lathe to turn the final OD and rear taper.

View attachment 142428 View attachment 142429

Completed part ready for final deburing.

View attachment 142430 View attachment 142431 View attachment 142432
Very Nice!

Tom S.
 

jbolt

Active User
H-M Supporter-Premium Member
Joined
Dec 3, 2013
Messages
1,226
Likes
1,010
#47
Here is the picatinny rail.

My original 3D model of the receiver was not correct so I had to spend some time drawing one with enough correct details to finish the picatinny rail model. I searched the interweb for dimensions of the radius of the rear bridge where the rear scope mount sits. It also sits lower than the front. Everyone I found was different and varied a lot so I figured out a way to measure it using a TDI in my drill press and a machine vise on a X Y table.

By zeroing the TDI on the center-line of the receiver and moving a measured amount right and left I could plot the radius. Height gauge was used to measure the offset.

Measure01.png Measure02.png

Here is the old (left) and new (right) 3D model.

Receiver_OLD.png Receiver_NEW.png

Machining of the picatinny rail. It was machined from 1" x 2" stock. The CAM was done with the model inserted into a model of the stock to set the coordinate origins for the top & bottom operations. The full rail is 22.2" long which exceeds my table travel so it was made in two pieces. The main piece shown here is 16.2" long

Tool paths.

PR-CAM01.png PR-CAM02.png

The bottom was done first. For the top operations the part can be held by the machined sides under the bevel and still have room for the cutting tools.

The rail has a built in 25 MOA slope when installed so all the bottom finishing operations were 3D tool paths.

After 3D adaptive roughing with a 0.5" 4 flute roughing end mill.

PR01.png

After the 3D horizontal profiling wth a 0.5" 2 flute ball end mill. Step over on the radius-ed areas that contact the receiver were done with a 0.012" step over. The balance was done with a 0.04" step over just because I like the look. When installed it is mostly hidden. The sides and bevel were done with a 0.375: drill mill.

PR02.png

Test fit on the receiver. Perfect! Unfortunately there is a shadow at the base so it does not show well in the picture.

PR03.png

Now the top.

PR04.png

Finished rail.

PR05.png PR06.png
 

Attachments

jbolt

Active User
H-M Supporter-Premium Member
Joined
Dec 3, 2013
Messages
1,226
Likes
1,010
#48
Before I can drill the mounting screw holes in the picatinny rail I need to assemble the hand guard and double check the measurement from the receiver mount holes to the drilled holes in the guard just in case of error creep.

The guard is pressed onto the guard mount and they need to be indexed to each other. To do this I made a jig to hold the guard mount so that the flat on the guard could be used for indexing.

The jig.

Jig03.png Jig01.png Jig02.png

Here is the stock partially assembled to do final measurements for the scope rail.

JT7-01.png
 

firestopper

H-M Supporter - Premium Member
H-M Supporter-Premium Member
Joined
Oct 21, 2014
Messages
1,135
Likes
1,990
#49
You do very nice work Jay, your extra effort in detailing and posting is inspirational. Keep it coming!
 

MontanaAardvark

H-M Supporter - Premium Member
H-M Supporter-Premium Member
Joined
Jan 3, 2015
Messages
260
Likes
102
#53
Good stuff, Jay!

Just found this thread, and need to add it to the ones I follow.
 

countryguy

Active User
Active Member
Joined
May 7, 2014
Messages
742
Likes
195
#54
Man oh man that is Sweet! My Son is going to flip when I show him this post! Two quick q's... What do you use for coolant flood? I'm ready to start that now also. In the pic below, you have two vises being used to hold a long part. I've been looking for something exactly like that. Not too small, Not to big. You happen to know who made those ? Again... AMAZING work. incredible patience!

...again, AMAZING post. 2vise.jpg
 

jbolt

Active User
H-M Supporter-Premium Member
Joined
Dec 3, 2013
Messages
1,226
Likes
1,010
#55
Man oh man that is Sweet! My Son is going to flip when I show him this post! Two quick q's... What do you use for coolant flood? I'm ready to start that now also. In the pic below, you have two vises being used to hold a long part. I've been looking for something exactly like that. Not too small, Not to big. You happen to know who made those ? Again... AMAZING work. incredible patience!

...again, AMAZING post. View attachment 229091
I'm currently using Koolrite 2290 coolant. So far this is the best I have found for being machine and user friendly. No rust issues and almost no odor.

The vises are 4" CNC style from Shars. They are great for the price but with a couple of drawbacks. The vises are not matched so one is a few though taller than the other and they only open 3.8". Other than that no complaints.
 

jbolt

Active User
H-M Supporter-Premium Member
Joined
Dec 3, 2013
Messages
1,226
Likes
1,010
#56
Now that life is settling down a bit this project is moving back toward the front of the line. Unfortunately I found and issue with the receiver block where I had modified a feature in the CAD model that had a relationship to the magazine well position. I didn't catch that and the result is the mag well is out of position by 0.1" which is too much to fix. Now that I have to remake that part I decided to change from a single stack magazine to a double stack ACIS compatible style. I'm also going to try some reduced shank end mills for the deep milling of the mag well and trigger well to see if I can improve the surface finish and avoid the chatter of the long flute end mills. I have some reduced shank end mills on order from Mari Tool so hopefully they will be here soon and I can get this project going again.
 

spumco

Active Member
Active Member
Joined
Jan 15, 2016
Messages
126
Likes
64
#57
Jbolt,

Superb. I bought a chassis for a Savage in my pre-CNC days, and your's looks every bit as nice.

FYI - American Gunsmith Tools is an off-shoot of Lakeshore Carbide, and they have some very nice long-reach reduced shank 3/8" end mills specifically designed for deep pocketing the magwell and FCP on AR10/15's. I have used mine and it's quite nice - so if the Maritool isn't to your taste I can recommend the AGT carbide stuff. I suspect anything you get from Maritool will be awesome, but I figured I'd just throw it out there as an alternate.
 

jbolt

Active User
H-M Supporter-Premium Member
Joined
Dec 3, 2013
Messages
1,226
Likes
1,010
#58
Jbolt,

Superb. I bought a chassis for a Savage in my pre-CNC days, and your's looks every bit as nice.

FYI - American Gunsmith Tools is an off-shoot of Lakeshore Carbide, and they have some very nice long-reach reduced shank 3/8" end mills specifically designed for deep pocketing the magwell and FCP on AR10/15's. I have used mine and it's quite nice - so if the Maritool isn't to your taste I can recommend the AGT carbide stuff. I suspect anything you get from Maritool will be awesome, but I figured I'd just throw it out there as an alternate.
Thanks for the heads up on AGT. I will keep them in mind. I had better like the Maritool cutters for the cost. LOL
 

jbolt

Active User
H-M Supporter-Premium Member
Joined
Dec 3, 2013
Messages
1,226
Likes
1,010
#59
Finally got to start on the remake of the receiver block. Based on the previous part I went through the CAM and refined some of the tools and tool paths. I was able to cut the top today which is the inlet for the receiver and magazine well. I'm super thrilled with the results of the reduced shank carbide end mills.

Here is the magazine well from the fist part. I used an extended length 3/8" HSS end mill and tried to take a full depth finish cut resulting in chatter marks. The corners were pre-drilled with a 1/8" hole so the cusps had to be filed by hand.

20170917_180824.png

Here is the new part finished with the reduced shank end mills. On this part I pre-drilled the corners 3/16" since the ACIS magazines have a larger corner radius. On both parts the mag well was pre-drilled with 1/2" holes and then roughed out with a 1/2" roughing end mill leaving 0.01" for finishing. I ran a 3/8" reduced shank carbide end mill set to do a finish pass and then a spring pass. DOC was .185" at 48 IPM, 6000 RPM. The final finishing to remove the cusps was done with a 3/16" reduced shank end mill with a DOC of 0.06" at 40 IPM, 6000 RPM. No filing needed and the magazine is a perfect fit.

20170917_201051.png

Here are the tools.

20170917_220216.png

And a shot of the completed inletting.

20170917_202236.png
 

Billh50

Active User
H-M Supporter-Premium Member
Joined
Jan 26, 2015
Messages
1,808
Likes
1,229
#60
Beautiful work !
I wish I had the capability to do that type of work. I can draw em but do not have the machinery or knowledge of cnc to do it.
 
[6]
[5] [7]