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Dennis & Brian's Build


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#41 sconigatman

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Posted 25 March 2014 - 09:30 AM

You guys really have it going. Very impressed with both the master and the student. Thanks for the suggestion on the sites.
Looking forward to more pics.

#42 Toolznthings

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Posted 25 March 2014 - 04:27 PM

You guys really have it going. Very impressed with both the master and the student. Thanks for the suggestion on the sites.
Looking forward to more pics.


Thanks !
Have to give credit to Dennis for the posts and pictures and the great job he is doing on helping to figure out this project. Fast learner and is doing a great job machining parts and helping in the shop.

#43 50BMGBOB

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Posted 30 March 2014 - 05:37 AM

Looks great and your pics have given me great ideals for the set up. I really need to get back to working on my Gat. Work has been to much lately.

#44 drhardin

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Posted 30 March 2014 - 08:36 PM

Thanks to all for the encouragement and kind comments. Glad to hear someone finds the posts helpful.

Unfortunately my wife decided she needed wallpaper taken down and painting done a week after we started this project so I had to abandon Brian for a couple of days to get things ready for the painters. Needless to say he did not sit down and eat Ponpons while waiting for me. Rather, he made large piles of chips turning big chunks of 1144sp in cam blanks, casings and cocking rings. We decided we did not like the thin, out of round brass or steel tube we purchased for the casing so he turned .250 thick wall blanks for the casing. He was kind enough to wait for me to help clean the chip pan. :o Sorry no pictures of that. He also ground a lathe tool to cut the first groove in the one piece cocking ring blanks on the lathe. We will finish the cocking ring blanks on a rotary table on the mill.

He also turned the fixture we will use the cut the cams.

#45 drhardin

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Posted 30 March 2014 - 09:18 PM

Here are some pictures cutting the outer groove in the cocking ring blank. We will cut the inner grooves using a rotary table on the mill. Brain ground the end mill that we will use to cut the bottom groove in the cocking ring that the button head screw on the hammer follows. We are not making that bottom groove as deep as the plans specify because it is only that deep so you can make the cocking switch from the same piece. We are thinking we may use that two piece cocking ring blank we made earlier for the cocking switch piece. We are making three sets of cams and three cocking ring blanks just cause we're paranoid.

#46 drhardin

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Posted 30 March 2014 - 11:27 PM

It’s time to cut the cams. We mounted the fixture in a collet chuck on the 4th axis on the Tormach. We cut the rear cams first. In addition to the two clamps at the back of the cam blank we drilled two .125” holes through the blank and into the fixture .500 in from the rear at 45 degrees from TDC and BDC for dowel pins. These were to insure the blank didn’t slip on the fixture. We put a piece of Duct tape over them to make sure they didn’t fall out as it rotated. Besides, who can build anything without a little Duct tape? :lol: We used CNCWrapper to wrap Y around A.

When we cut the front cam we drilled the holes in .250 from the front of the cam or we thought we did. We haven’t figured out why but the front cam ended up .017” short. If that had happened to the rear cam it would have been a big problem but the front cam being .017 short really doesn’t matter. Just wish we knew what happened. Not knowing what happened is what’s really disrupting. :oops:

#47 drhardin

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Posted 30 March 2014 - 11:43 PM

We received our new hex sleeves so while I took care of the Tormach cutting the cams Brian made an arbor to turn the hex sleeves so that the inside hex was concentric to the od. When we purchased the original hex sleeves and Loctited them in we were not happy with the results so Brian bored them out and we ordered oversized sleeve so we could turn the down.

#48 drhardin

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Posted 31 March 2014 - 12:01 AM

Now we can Loctite the hex sleeves in the bolt carrier and front barrel ring. The sleeves are shorter than the bolt carrier so it takes a full sleeve and a short piece. We decided not to Loctite the short piece since it really is just a filler and could cause another alignment problem.

#49 drhardin

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Posted 31 March 2014 - 12:31 AM

We needed a morale booster and some motivation so we decided to put the barrel assembly together. It is a great feeling when you get to this point. We only put the firing pin and hammer in one bolt. We still need to fix the button heads in the hammers.

#50 42rocker

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Posted 31 March 2014 - 01:38 PM

Nice Work and you keep on moving. Hope to see more.

Later 42rocker

#51 sconigatman

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Posted 01 April 2014 - 09:05 AM

Dennis and Brian,

Must have missed it. What did you do about chambering your barrels?

#52 drhardin

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Posted 01 April 2014 - 10:57 AM

Dennis and Brian,

Must have missed it. What did you do about chambering your barrels?


I posted that on March 20th. If you check in about the middle of page 3 postings. We purchased a finish reamer to do the chambering.

#53 sconigatman

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Posted 03 April 2014 - 10:18 AM

There it is. Rt angle mill head, eh. Hadn't thought of that. Have to add that to the knowledge base.

#54 drhardin

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Posted 05 April 2014 - 12:21 AM

To finish the cams we needed to cut the slot for the bolt extractor. We used the same fixture that we used to mill the cams on the CNC mill. When it was in the CNC we milled a reference flat at 0 degrees on one side and at the 15 degree offset where the slot is cut for the bolt extractor. Using the zero reference we indicated the fixture, drilled and reamed two holes for 3/16 dowel pins. We set the fixture up in the vise with the pins on a parallel and milled the slot in the back cam. We then turned the fixture upright with both cams on it and did the front cams to match the back.

Now, for the big however, the 1144 stress proof is not totally stress proof. After we cut through the back cam and took it off of the fixture it closed up .035”. Both side curled in and closed, although the one side did curl more than the other. This means the bolt extractor will not fit in the slot and the cam is curled inward toward the bolt carrier. This caused many hours of frustration, consternation, and anxiety.

Brain decided to turn another cam blank oversized, cut the slot, turn to final size and part it off. Unfortunately it did the same thing. Next, we took a jack and spread the cam as shown but it would just spring back when we took the jack out so we will try cutting a slot opposite of the bolt extractor slot but not completely through to see if we can spread it and get it to stay.

#55 DonLans

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Posted 05 April 2014 - 04:53 AM

Mine collapsed too. This is what I did to spread it. I forced it open an extra .030" and I put a torch on the opposite side and let it cool that way. Then it was slightly too wide. But at least when I put it in the casing it was then forced to size. I didn't know what else to do. It may depend on the material what will happen.

#56 bruski

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Posted 06 April 2014 - 02:40 AM

If you guys make another one, heat the material to aneal it and releave the stresses before you cut the extractor slot.
bruski

#57 sconigatman

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Posted 06 April 2014 - 01:08 PM

I guess I was lucky. Mine expanded about .01. Ended up being a nice fit once I collapsed it a little

#58 my65pan

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Posted 06 April 2014 - 06:52 PM

I used 17-4 for my box cam and didn't notice any distortion, but I cut the bolt extractor slot before I cut the cam slot. Don't know if the sequence makes any difference, but thought I'd mention it.

#59 Toolznthings

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Posted 07 April 2014 - 12:50 AM

Hi All,

For sure, we all new trouble was brewing when we saw the cut thru in the rear cam. :shock: Was hoping for the best from the 1144, but to much stock to remove. Thanks for the replies and other solutions !

Brian

#60 drhardin

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Posted 07 April 2014 - 05:40 PM

I am about 5 days behind on posting our progress and about 10 days behind Brian on making parts. I will try and get posting of our progress caught up today and on turning crank handles later this week.

We did think of trying to heat the cam and spread it but just wasn't sure where the part would go if we heated it with a torch. Yes, I think we should have heated it before we cut the slot but my foresight isn't a whole lot better than my hindsight. What we decided to do was to cut a slot in the bottom of the back cam and spread it and let it relax until the slot for the bolt extractor was correct. Brian made a fixture to locate and space the cams as shown. Since the back cam was tight, due to the distortion, we pressed the whole assembly into the casing using a plug cut to the correct depth. This located the whole assembly to the correct depth so we could screw it to the casing.




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