Building the Stevens Favorite

[Tom Griffin]

RE: Building The Steven's Favorite Tonight's task was the one thing I dreaded about making the lever. On the lever of the original Steven's, there was an internal pocket centered on the pivot to clear the end of the extractor which shared the same pivot point as the lever. It was a simple feature to include because the lever was cast and the pocket was just another part of the pattern. Since I am machining this lever, I had to either engineer the pocket out, which I couldn't figure a way to do, or machine it, which would be tough since it would be a blind cut inside the lever and the only access would be through a 9/32" pivot hole. The technique I decided to use was to make a single tooth cutter that I could insert through the 9/32" hole and use it as an end mill by rotating the lever on the rotary table. The catch was that since the shank diameter of the cutter would be 1/8" and the diameter of the pivot hole 7/32", I would only be able to move the cutter over about .04", not enough to machine the full diameter of the pocket in one setup. In other words it was going to take three different sized cutters to machine the pocket. The dastardly pocket can be seen in the section view of the drawing shown in the photo above.

The cutters were made of O1. I turned the 1/8" shank on the lathe, ground the form on the belt sander and grinder, hardened and then sharpened it. I almost completed the first cut, but the cutter shank broke at a stress point. I made another with larger radii and tempered the shank, leaving the cutting edge nearly full hard and the shank a bit springy. This one worked much better and I was able to finish what was left from the first pass plus a bit more. One more cutter will take the pocket to the full .406" diameter.

These simple paddle cutters are easy to make and should be considered when making a project. You can make them exactly the size needed and not have to settle for something close or spend a lot of cash to buy one. This one would work just as well as a boring bar instead of an end mill with some slightly different angles,. The cost was a 3" long piece of 3/8" drill rod and about 10 minutes worth of time.



The first cutter. This one was small enough that it fit straight through the 9/32" hole.



The second cutter, slightly larger diameter with the shank tempered blue for flexibility. This one had to be rocked through the hole which was a pain to set up, but it worked great.



The cutter in place, with the lever mounted on the rotary table, after taking three passes to cut the internal pocket.

Now that it is all finished I've found there is a better way to do the counter-bore. Jim Wisner pointed out that on the samples he uses to make reproduction parts, the counter-bore is cut through one side of the lever and then the outside part of the counter-bore filled with a bushing. Sounds like a good addition to REV B.



The next task will be to make the link and pins that connect the lever to the breech block. Then operating the lever will actually open and close the breech block.





The lever is finished, save some contour filing and polishing. I went ahead and made the link and the pins to attach it to the breech block and put it all together. Unfortunately I got ahead of myself and didn't take any pics. It's pretty encouraging to see everything operate as it's supposed to when the lever is cocked.

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"Aviation is going to make such progress as cannot be imagined."

 

[Tom Griffin]

RE: Building The Steven's Favorite Not much time for the project tonight. Between a couple of chores and tip-off time time, I was only able to make the screw that attaches the end of the mainspring plunger to the receiver. Just a simple 8-32 thread, a .04" wide parted groove and a screwdriver slot in the head. This is the perfect application for a collet block.





The next task will be to make and install the pin for the clevis and to wind the mainspring if I have the right size music wire on hand.

Tonight I got started on the mainspring plunger. The Steven's uses a compression coil spring for a mainspring and it sits on a rod with a clevis on one end with a pin in it that pushes against the hammer. The other end rides in a bushing that hooks on the grooved screw that I made last night.



The first step was to square up a piece of O1, rough out the turned end and center drill each end so it could be turned between centers.



I rarely turn between centers so I didn't have the proper size dog on hand. The alternative was to drill an oversized center in the yoke end and use that to drive it. Thye driving center is just a piece of aluminum turned to a 60º point. It should work fine because the shaft is only 5/32" diameter and won't require much torque to drive.





The radii were cut with a corner rounding end mill. Next, the center of the clevis gets milled out. Not tonight though, it's been a long day. I'll be working at home in the morning and will need the mill so I guess I'll just have to finish it then.



Toolmaker's clamps aren't used often, but they worked well here to stabilize the .075" thick fingers on the clevis. Even so, with the long thin fingers and the long end mill, the potential for a spectacular wreck was high.







It's a nice day outside but I still managed to sneak into the shop for a bit and wind the mainspring. The method I use to make springs is to set the lathe up for the number of coils per inch, put a slotted wooden insert in the tool block to pinch the wire and provide tension and wrap it around a mandrel under power. The spring always ends up larger than the mandrel so figuring out the right size mandrel requires some experimentation. Once wound, it was clipped to length and the ends ground square on the belt sander.



This is the wooden tensioning block sawed out of a leftover piece of walnut from the stock. The amount of tension required depends on the diameter of the wire and sometimes takes some trial and error to get right.



Safety glasses are a must when working with any kind of wire, especially when winding springs. The mandrel I ended up using was a long aircraft drill about .015" under the finish diameter of the spring. Forcing springy wire to conform to the shape you want is a dicey proposition, so it's best to run the lathe at slow speed and stay well clear of the wire. The end of the mandrel is supported with a drill chuck snugged up and well oiled. The start of the spring has a 90º leg bent on it and pinched in the lathe chuck along with the mandrel.



The finished spring mounted on the mainspring plunger.



The spring force on the hammers feels a tad light, but it is only a .22. If it misfires I'll just re-wind the spring with .055" or .063" wire instead of the .047" I grabbed at the hobby shop. The hammer doesn't fall all the way yet because I still need to cut the notches and the extra stock is hitting something inside the receiver.

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"Aviation is going to make such progress as cannot be imagined."

 

[Tom Griffin]

Today was hammer time. In between spring cleanup, I managed to get most of it completed. I chose to mount it on a sub plate as with the breech block and the receiver only the hammer only had one hole in it so I had to add another in an area that would be cut out. I also decided to forego the screws and just use pins, relying on the clamps to hold everything down. I made a design change on the fly and added some extra material on the top for some cocking serrations and also some additional material on the half cock notch to make it more "safe" since the half cock position is the actual safety.



Here, the blank is mounted to the sub-plate that has all the center holes located just as with the receiver. Since there are a few radii that end on this part, I had to indicate the edge of the sub-plate and zero the degree scale as well as center it on the rotary table.



Since there was only one hole in the hammer, I had to be sure to clamp on the hammer while machining to keep it from moving.



The rough shape is finished. The half cock and full cock notches still need to be cut and the top of the hammer serrated.

Cutting the notches in the hammer turned out to be a royal pain. Not because it was difficult work, but because I neglected to get the machining order straight before starting the part. With all of the different angles, it would have been much easier to machine the notches before milling the outline of the hammer. Then there would have been lots of straight and right angle surfaces to work off. The two angles of the full cock notch were cut and the half cock notch roughed out with and end mill, then the half cock notch was finished with a form ground fly cutter.



This was the setup used to cut all of the angles on the notches. Some of them were set with a sine bar and some with a protractor. This pic shows the form cutter ground to cut the deep half cock notch. The bluing (Magic Marker) serves as a witness to show when the cutter touches.



The finished hammer. Each of the eight different angles around the notches was a separate setup.



This shows how the breech block, lever, connecting link and hammer all interact. In this pic, the lever is being cocked and the link is pushing the hammer to half cock. Once there, the link will pass the hammer allowing the lever to actuate the extractor, which is farther down on the task list. I think it only makes sense to make the trigger next.
I had to use the shop for actual work today and between that and the Wings game, not much got done on the Steven's. I did manage to make the sub-plate for the trigger and get a piece of O1 mounted on it, but nothing photo worthy. As soon as I get the use of the mill back I'll get the rotary table back on and start cutting the trigger, probably tomorrow night. My significant other is up north through next week so I'll have a lot of Steven's time when I'm not holding down the fort.

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"Aviation is going to make such progress as cannot be imagined."

 

[Tom Griffin]

RE: Building The Steven's Favorite I got most of the trigger finished tonight. It took longer than expected because I decided to make some changes on the model to make it easier to machine. The sear was the hardest part just because it was so darn small and hard to see. This part was a good application for carbide tooling just because the end mills required were so small and long and the material was tool steel. I don't use carbide much, but it was handy for this application. Next is the backside of the trigger and possibly rounding off the front so it feels better on the finger (another thing I changed on the model).



After mounting the trigger to the sub-plate, the first two cuts were made on the front of the trigger.



Next came the back side of the sear (on the right) and the flat that the trigger return spring pushes on.



The sear tapers 10º to .030" which matches the half cock notch in the hammer.



The newly added curve on the front of the trigger was milled to a 3/8" radius with a form tool mounted in a fly cutter. It was ground on a 5/16" tool bit and mounted in a fly cutter, then the part was spun on the rotary table against the spinning form tool to generate the curve.



The radius on the back side was milled to size with a 3/32" carbide end mill.

The machining is complete and it's ready for hand finishing.

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"Aviation is going to make such progress as cannot be imagined."

 

[PurpLev]

that is awesome!

thanks for posting these... very inspiring - beautiful work you've done there.

 

[clearcaseman]

It is so hard to decide if this is a piece of work... or a piece of art...
I would love to make something like this to shoot 50 cal Beowulf.

 

[bodger]

Absolutely fantastic work, and a real learning experience just to watch! Thanks for taking the trouble to show it.

bodger

 

[Tom Griffin]

Thanks guys.

The Steven's project has been pretty much idle lately with the summer schedule, but I'm starting to get the bug again. Not sure if I'm going to continue updating the thread here, or just on www.MetalWorkingFun.com. Either way, there should be some exciting installments over the next few months with the work needing to be done on the barrel.

Tom

 

[Tony Wells]

You should try to do both, Tom. We're running parallel and friendly sites, Ed and I....so we would welcome it here as well.

 

[Tom Griffin]

OK, I'm back from vacation and will pick up on the build where I left off...

The weekend was pretty productive for the Steven's project. I played around with the action a bit and decided to re-design the connecting link a bit because it was binding a bit on the hammer after raising it to half cock. CAD is very helpful but it doesn't provide the feel you get by operating something mechanical with your hands. I also turned down the breech end of the barrel and machined the socket in it where the barrel screw seats. That allowed me to check the over center operation of the lever and breech block. It worked perfectly holding the lever tightly against the underside of the receiver. The barrel screw turned into quite a project with its convex straight knurl and a couple beads that I added on each side to dress it up a bit. I apologize for the lousy pics but the wife took the point and shoot camera up north and I was forced to use my son's Nikon D700. It's a GREAT camera but I haven't used it enough to know how to change things like shutter speed and aperture and it is ALL electronic. Consequently I have a bunch of pics with zero depth of field.



The homebrew convex knurl was made by plunge cutting 90 teeth in a piece of 5/8 drill rod with a 60º cutter and mounting it on a bar using a dowel pin as a shaft.



This is the barrel screw in progress. The area under the knurl was pre-cut with a form tool that had the same radius as the knurl. It produced a nice clean knurl although I noticed that some of the teeth chipped off along the edge of the knurl. Guess I left it too hard.



Form tools were also made for the beads on each side of the knurl and the radius relief under the head. The thread is a single point cut 5/16-24. The angled point seats in the barrel to index and hold it in place.



I still need to cut the coin slot in the head. I didn't have the right diameter cutter so it'll need to be cut on the rotary table.



I may shorten the barrel screw a bit so none of the threads are showing.



This is with the breech block open showing how it drops down to allow a cartridge to be chambered.



Tonight was a bit of a milestone. I broke out my trusty slotting tool and finished squaring up the corners in the receiver to make room for the trigger return spring. I didn't have any 1/32 spring steel on hand so I made a temporary spring out of phosphor bronze. Now with the extra material removed I was able to install the hammer, trigger and the return spring and check out the operation. The hammer now falls all the way to the breech block and the sear catches the half cock and full cock notches as the hammer is raised. The trigger pull is a little light for my liking but that will get heavier with a stronger steel trigger return spring and some work on the notches in the hammer.

I forgot to cut the clearance for the mainspring when I made the stock so that will be next, then it's time to make some wood screws.