Cutter's Bolts and Extractors

[brk]

Working on the Gatling Gun again...  started 17 years ago!  Maybe 2020 is the year to finally finish.

 

BOLTS

I have the box cam completed and the complete breech casing, frame, etc and using Cutter\'s (Jerry\'s) one piece bolts.  I am at the point of cracking and seeing everything mover around. I am getting some drag on the \"square patch\" around the cam pin on the bolt with the inside diameter of the box cam. This square patch is a left over amount of material left after the pin is machined, then the bolt stood on end to remove the rest of the hub that was used for the pin.  The diameter of the bolt head under the end cap is .490 and this patch stands proud of the surface about .020\", which would be about .015 over a .50 diameter.  The bolt head/caps measure .50.  With a .50 diameter, there is only .010\" clearance between the inside of the cam (2.520\").  I guess I could have made the cam with a larger ID, the solid piece would be easy enough to bore out, but the rear piece is another story. I filed the \"square patch\" down on one bolt and it slides freely in the cam with the carrier block and barrels all assembled and cranks very easy. No cocking section yet, just moving bolts in and out.

 

Anybody else ran into this interference issue with the way the one piece bolts are machined leaving this little \"square patch\"?    The bolts diameters that go in the carrier block are measuring .416-.417\".  My carrier block bores are measuring .4195-.420\".  Enough clearance to be able to crank with the interference, but definitely need to be address the drag on the rest of the bolts. I had bought some extra, so had one to play with.  Just wanted to know if there is another way other than filing down the extra material on the bolts. They look great as received and filing will have some cosmetic issues.  Won\'t see it inside the gun, but I will know it is there.

 

 

RUGER STYLE EXTRACTORS

I also had bought ruger style extractors from Cutter with the bolts.  I made a jig to hold them for the machining like what was posted on one of these pages.  Does anybody break the edge of the square piece of the extractor that will be sticking in the hole that is at a 5 degree angle?  a sharp edge seems not so good.  Breaking the edge will allow the extractor to move forward and more clearance on the rim of the cartridge.  Anybody done anything with this?  I do have a .dxf file from Cutter for the machining.

[Sparky_NY]

  Just wanted to know if there is another way other than filing down the extra material on the bolts. They look great as received and filing will have some cosmetic issues.  Won\'t see it inside the gun, but I will know it is there.

 

 

 

 

Some filing and hand fitting is done on the finest guns in the world !       When tolerances get real close and part fits need to be perfect,  its the method gunsmiths have used for centuries.     The particular area you are having problems with is a very close clearance which is a good thing, it gives the bolt lugs maximum contact area on the cam surface.

 

Cheap, mass produced guns are made with excess clearances so no hand fitting is required.    Its the difference between a $300 and a $3000 gun.

 

I vote for filing the area and rest at ease knowing you are following in the footsteps of the finest gunsmiths in the world.   

[4171]

Ditto!!

Mike

[Cutter]

Run out between the bolt holes and the center bore

will cause the interference condition.

 

This video shows an extreme condition

[brk]

BOLTS

I am filing down the material around the pin on the bolts, got 7 done, 3 to go.  I don\'t have the runout like in the video.  I checked the OD of the carrier block with the main shaft in vee blocks and I have about .0025\" TIR.  I then checked across the top side of a bolt in the carrier block, moving the same bolt hole to hole and have about .003\" TIR across all ten holes in the carrier block.  I do have some clearance between the hex main shaft and the broached hex bushing I had used.  I am thinking about using some .001\" shim to take out the clearance between the hex shaft and bushing to influence the carrier block a little in the direction to reduce the minor runout.  I don\'t think this runout is the drag issue I was having.  The material around the pin seemed to be a little too high.  When I get the ten bolts in and this back together, I will to to post some pictures.

 

RUGER STYLE EXTRACTORS

Any feed back on the question about the breaking the edge on the extractor that will pivot in the 5 deg cross hole?  I will be working on the final machine of the bolts after the cocking ring and switch.

 

Thanks for the prior feedback and any you can give on the extractors.

[gbull]

I really don’t think breaking the edges of the pivot leg is necessary. If Ruger didn’t see a need why look for trouble were there isn’t any. If the hole is in the correct place everything should work.

[brk]

I filed the bolts around the pin and polished them.  The bolt cap is right at .500, so is a little proud of the end of the bolt head. I broke the edge and polished with 600 grit paper to remove the forward sharp edge. This should not hit the inside of the cam, but with some extra clearance between my carrier block and the bolt, it guess it might and didn\'t want a sharp corner rubbing and causing issues.  I tried to shim .001\" between the hex main shaft and hex bushing to reduce rounout of the carrier block.  I found this wasn\'t the answer. I foudn that when tightening the nuts on the main shaft to the carrier block, it influences greatly the amount of runoff.  I back off how tight I had them and was able to get them tight with about .0015\" runout.  They are just a little past snug, then jammed with the second nut.  I put a light wiping of gun grease on the bolts, cam surface, bushings, thrust bearings and it runs smooth.  I tired to post a video, but couldn\'t, if someone can tell me how to post pictures and video, I will put them up.  Might start a new thread for progress in Southern Illinois.

[brk]

I think I figured out how to post a video, hope this works.   This is with the magazine off.

[brk]

OK, that didn\'t work

[brk]

The two rotating groups below the one in the video in the prior post are from a retired friend of mine.  He passed them on to me.  I made mine with a slightly longer cam, 1.20\" which I thought I needed to work with the drum magazine, it has the same path as the 1.175\" in the plans except in the top of the cam path which travels backwards a little more.  The other two are setup for 1.175\" cams, I got two of those made while I was making the 1.2\" cam. I had a machine shop run them for me, made them from brake die (4140 prehard to 32 HRC). Here is a video of the drum magazine.  It doesn\'t like to feed long rifle through the escapement wheel. I redrew everything and am making some feed lips to attach to the bottom of the magazine, I mocked it up with some washers and tape and it seemed to help, so I am thinking that I can get it to work.  I know that Paul Moore doesn\'t recommend making the drum magazine, but it looks too cool not to use.  I also think the timing of the drive pins isn\'t right to the bullet catch grooves, I think the drawings is reversed.  Seems the pin placement is mirrored (first project vs third projection drawing).  I also think moving them out to a slightly larger BC will help. I did have my pins higher than what is in Paul\'s drawings. This required a groove in the magazine well and some minor notches in the side frames with the pins sticking out of the barrel plate a little more.  When I drew everything, it seemed the pins where just a little too short.  Anyway, I can get the barrel plate to move the escapement wheel without binding. I have to remake the escapement wheel to correct the mirror issue and then will move the pins in it to a slightly large BC.

[brk]

second try on the magazine video.....

[brk]

here are some pictures of the tripod and gun mounted on it.  I still need to make the oscillator parts to keep the nose of the gun from falling (ignore the yellow pipe cleaner keeping the back of the gun down). I went with 16\" barrels so it is a little nose heavy now, but think when I get the rest of the part on, will likely be balanced of slightly rear heavy.

 

I still need to make the following for the gun:

1.) cocking ring

2.) cocking switch (have the knob done)

3.) bolt extractor knob

4.) strikers

5.) machine the bolts for the Ruger style extractors

6.) plungers for extractors

7.) finish the oscillator parts (have some made but not all)

 

For the tripod:

8.) a clamp for the swivel plate

9.) something to keep my acme elevating screw from turning (I machined an 1/8\" wide slot down it)

 

When I get all that done and this thing shooting, them maybe a fancier yoke.

 

[brk]

Looking at the pictures reminded me, also need to make:

10.) front sight

11.) a magazine well latch (not in the plans, read from various places this is needed)

12.) an ejector blade (thought I think I read that with a little more firing pin extension, it may not be needed?? - COMMENTS?)

13.) a latch for the drum magazine door (don\'t like the jewelry box latch but the hinges are OK I think)

14.) a better crank handle/knob (the current one is a bought plastic one)

[Sparky_NY]

The gun looks fantastic !      Tell me about how you made the medallion.     A medallion is one of the finishing touches needed on my .357 gat and I keep procrastinating how to do it.

[brk]

Thanks for the feedback on the gun.

 

I bought the medallion from Paul Moore some years ago, not sure what I paid, might have been $40.  It was flat.  Made some forms from heavy tubing, annealed the piece, then pressed it to close to the right ID, annealed a second time and pressed some more but could not get a 100% correct ID of the medallion to match the OD of the breech casing.  Then took a piece of heavy wall aluminum tubing, turned it about 2.980 (.02 less than the 3\" OD of the breach casing), contact cemented on some 180 grit sandpaper (about .010\" thick) and sanded it to match the curve of the breech casing.  I drilled some holes 74 degrees apart and used #2-56 screws to attach.  The breech casing is drilled through and I tapped into the box cam section.

[Richard Morton]

Hi, good looking work.  I wonder if I could trouble you to post a few more pictures of the magazine and how it is attached to the case. 

[brk]

I hadn\'t looked at the site much since Christmas, so just saw the request for more photos. I will post some pictures of how the magazine is mounted. It is mounted according to old RGG plans from back in the early 90\'s when Paul supplied the drum magazine plans.  There is a piece soldered on the magazine well that has an 1/8\" dowel pressed into each side.  The right side of the breech housing has a 1/8\" slip fit hole, then there is a second piece of 3/8\" wide brass mounted to the frame in front of the magazine with an 1/8\" slip fit hole.  The magazine well stills needs to have a latch on the left side to keep it close.  The latch isn\'t in any of the RGG plans. I had seen some solutions to this on the RGG site years ago.  Pictures to follow in a couple days, likely this weekend.  

[brk]

Had not internet the last week so finally got to be able to post some pictures of the drum magazine mount, pretty much to Paul Moore\'s early plans with a drum mag.