Posted 30 July 2013 - 05:23 PM
Also see more posts on modifying the cams. These are edited.
I'm building the D&E GG and seen your posts on the GG forum. Did you have
any success with modifying the cam box slope? I haven't made those parts
yet but wanted to know if that mod made any difference or not.
I have read your posts.
I can not locate my notes on the cam modifications.
Yes, it does make a difference in the amount of torque on the crank handle and the smoothness of the travel.
The purpose is to eliminate the abrupt change in direction
when the lug hits the cam.
The plans call for moving one hole on the dividing head
and 0.005 on the table to produce a 45 angle.
I started plunging at the entry groove.
I moved the head one hole and the table 0.001 for several
holes, then 0.002 for several holes, 0.003, then 0.004, and
then 0.005. This created a curved slope on the cam instead
of the abrupt angle.
I will keep looking for my notes.
Hope this helps.
Interesting method. Did this modification create any binding, jamming, or ejection issues?
I still can not find my notes.
The five divisions are not correct.
I will make another cam and come up
with the correct figures.
Hope this helps.
That would be great Steve! At this point I'm not well studied on the mechanics of how the two cams work the bolts in tandem. Based on your findings it sounds like anything done to reduce required torque would be a worthwhile endeavor.
I last finished drilling the .313 hole in my bolts. Next step is to counterbore and tap for the plug in the end. I had to order a size ought center drill for the firing pin hole. The smallest I had was size 4, much to big for the .089 hole in the end of the bolt.
Appreciate all your guidance!
The bolt lug touches only one cam at a time. The space between the two cams at the angles is just empty space.
As the bolt is inserted into the entry hole the large, flat area of the front cam keeps it in the correct position so the end of the bolt will slide into the cocking ring. (I have replaced the round tip of the bolt with a ball bearing. It cuts down on the friction. I have tried other things here also such as using UHMW plastic and a curved, linear ball bearing in the cocking ring). The cam contacts only the front side of the lug. As the bolt carrier is rotated by the handle the lug moves until it encounters the acute angle of the rear cam. The spring is compressed as the rotation continues. The cam contacts only the rear right corner of the lug. (This is the beginning of the firing problems. By the time this first bolt reaches the firing position the next two bolts are also being compressed making it difficult to turn the handle. This why I modified the cam, to lengthen the travel it takes to compress the three springs and to lessen the degree of the angle so the handle would turn more freely). The lug moves along the angle until it is fully cocked and reaches the smaller flat on the rear cam. Here the round has been fully slid into the chamber and the ejector is in contact with the rim. The rear part of the lug is now in contact with the small flat of the rear cam. The spring keeps it in contact. This is what absorbs the shock of firing and why the cocking ring must be tight against the rear cam. (The weakness of the ejector and the fit are more firing problems).
It travels on this flat until it is released by the cocking ring.
(The position, shape and spring pressure of the firing pin are the next firing problems).
Here the ejector starts to pull the round out of the chamber as it engages the acute angle of the front cam. (The ejector has always been a problem). It contacts the front, right corner of the lug.
It rides on this angle, dropping out the round until it hits the other side of the rear cam before the entry hole. Left, rear corner, but mostly the rear of the lug. It passes the entry hole and starts over.
That explains it quite well, thank you Steve. I had only a cursory understanding until now. I'm going to follow your instructions on the cam mod.
So, did you start the cocking angle right at the beginning of the entry hole or did you leave a small flat here? What your calling the entry hole is the slot in the rear cam that allows removal of the bolt correct?
I'm just about done with the firing pins. I made them out of two pieces. The body is made out of 416 SS and the pin is made out of W1. I'm going to quench them in oil after silver soldering to harden them up. I made the bolt body from 8620 and the lug out of O1. Will harden both of them as well but will have to be careful since the lug is soldered on already.> Take care!
As you can see I have not received many replies to my posts.
Would you mind if I copy our PM messages and post them on the forum?
Then we can continue on the forum so someone else might benefit.
I do not consider my posts to be instructions but just the way I am proceeding
to solve the problems I have found.
Feel free to cut and paste.
I'm building the pins to print for now. I've read the post about modifying the pins as well as the floating design from Roller. I'm not entirely convinced the issue is not weight of the pin assembly. If there was more weight flinging forward, the pin end would be less critical.
Posted 19 August 2013 - 10:24 PM
I continued on by turning the lugs to size.
I made the turning fixture as per plans.
DSC00293-id=1400.JPG 17.81KB 0 downloads
I colored the lug blue for clearity.
This is when I started to have trouble as some of the
lugs were harder than others.
I switched to a carbide cutter.
DSC00294-id=1401.JPG 28.91KB 0 downloads
I made the offset fixture per plan. Make sure
to get the 5.78 offset in the correct direction.
DSC00295-id=1402.JPG 17.15KB 0 downloads
I turned the offset to size.
DSC00296-id=1403.JPG 27.46KB 0 downloads
I faced the offset and center drilled.
then I drilled the #43 hole.
This is where more problems arose as this is
deep hole drilling.
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Posted 19 August 2013 - 10:42 PM
I broke a few bits before I stopped
and made a peck drill.
DSC00299-id=1405.JPG 24.96KB 0 downloads
Using this I have not broken another bit.
I also found that the center of the #43 hole
and the 5/16 hole were not lining up. So I
drilled the #43 hole as deep as I could so the
5/16 bit would meet it and follow it into the
center of the #43 hole.
DSC00300-id=1406.JPG 35.32KB 0 downloads
I drilled the 5/16 hole.
DSC00301-id=1407.JPG 25.78KB 0 downloads
As I am using the 4mm non rotating firing pins
I drilled the entire depth of the hole using a
letter Q bit. This is the tap sise for the 3/8 x 32 thread.
I then taped the threads by using first a tapered tap
and then a bottoming tap. I cut five threads.
DSC00302-id=1408.JPG 37.78KB 0 downloads
Posted 19 August 2013 - 11:42 PM
because of the unexpected hardening of the material.
I chose 7/16 drill rod as I want to harden the end of
the offset that touches the brass round. Some of the lugs were
so hard that they destroyed the hss turning tool. Without quenching.
Others were very soft. I concluded that it was the the maximum
temperature reached while hard soldering. It is difficult to
maintain a constant temperature using a torch.
I changed to a carbide insert cutting tool to finish turning the lugs.
Broke a few inserts. Should have waited until I annealed them.
I separated the hard pieces and cleaned them. Then I heated them
to a dark grey color and let them air cool.
And I tried drilling them again. About half were ok. The others were
still hard. I tried to anneal them again and got most of them soft
enough to drill.
The next problem was that though they would drill they would not drill
centered the entire length. This is important because the firing pin spring
retaining nut will rub and cause interferance when firing.
I set these aside and then tried a carbide boring bar. This worked
on most of them but a few were still not centered. I set these aside
until I made some more boring bars. The commercial ones I had all broke.
I have not resolved this issue yet.
I stopped to do reading and research on heat treating and hardening. I want
to set up a much better heat treating system.
I selected ten bolts that had a soft lug to use as a control group with the
firing pins as per plan for testing.
I selected another ten and then hardened the lugs for a control group for
testing against the soft group. I heated them until they were a dull red
just under the hard solder melt temperature and the dropped them in
a can of oil. I did not harden the end as the final length had
not been determined yet.
These will be used in combination with different firing pins to measure
the inch pounds of force needed to operate the crank handle. I need to
look back at Roller's posts but I think he said he had about 25-30 inch pounds
to turn the handle,(I could be wrong), I have gotten down to 11 inch pounds.
I want to establish a measurement of force that I can refer to
when doing this build. It is not completely scientific because the measuring tools
I bought from EBay are not calibrated but it is better than what I feel with my hands.
I have made ten firing pins per plan using the specified springs.
I have also made a set of ten non rotating 4mm pins using a larger id spring
and a ball bearing for the end.
Have not done any testing of these yet. I have been able to turn these in the
test stand without breaking the crank handle gear pin. I have not tested
the per plan cam against the modified cam as yet.
Posted 08 September 2013 - 08:06 PM
Posted 04 November 2013 - 12:28 PM
I relocated from NY state to SC back in march and sold my machines because they were just too difficult to move. I am now in the process of getting machines and hope to return to my D&E gun before too long.
Hope all is well, look forward to more D&E adventures.
Posted 15 November 2013 - 01:27 AM
Posted 17 November 2013 - 03:00 PM
Making most of the ggun is just a matter of following
the plans. The problem is in the firing and that is what
has interested me. I have tried several ways to improve
on it. What I have found is that the round firing pin does
not strike the rim of the round. Making the bolt carrier
of two pieces allows its position to be adjusted.
Changing the firing pin to a non rotating design helps.
I have not finished the modifications and testing.
The only gun I know of that fires well is Roller's.
I suggest you study the design and the posts here to
get the information available. This is the only active site
that has this information on the d&e.
I will make some more posts on testing and progress as
soon as I finish some other projects.
I am sure this design can be made to fire. My goal is
100 rounds with no misfires.
Roller's gun uses the plans design for the extractor with modifications.
Steelcrafter was to use a finger extractor.
I have been working on the spring finger design but have
had trouble locating the 1075 annealed shim stock I need.
Also need a heat treating oven.
Cutter is a very good resource and is always willing to help
but I think he cheats by using magic tools in a darken workshop.
I have been concentrating on experimenting to improve the
firing so have not progressed much on the rest of the gun.
By adjusting the position of the firing pin where it strikes
the round I have been able to achieve 100% firing on
my test stand.
With your experience you should be able to produce
a first class gun.
Posted 17 November 2013 - 09:40 PM
I worked on the bolts until I was able to get several to fire
100%. I had to adjust its position, one of the reasons I
made the bolt carrier two pieces. I stopped on the bolts
and did a series of tests. Need to post the results. I
got to the point that I need a heat treating oven instead of
using a torch. I started to make one, and have been working
on other non ggun projects. Will post some more when I finish the oven.
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