Just getting started on an RG

Made a couple of plates and that\'s it so far.  My main mill is now CNC, so I\'m using this project as motivation to really learn to use it.  I\'ve made some steam engines and a bunch of other random projects, but I have no formal machinist training.  Should be entertaining.

I think I have all the errata and a couple of improvement ideas (spring steel extractors, one-piece cocking rings as posted here) but any more thoughts and suggestions are welcome.

[Dave]

How is your progress?

Thanks for reminding me I hadn\'t posted anything lately.
I\'ve made a few more bits and pieces; the frames, bows and some little parts.

I\'m working on the box cam now.  I found no hardware stores nearby carry 3\" PVC pipe for 4th-axis test cutting material, but they do have 3\" PVC Conduit over in electrical and that works pretty well if you buy eight feet.  Time to play with metal now.  Hopefully the DOM tube I have won\'t pretzel itself during cutting.

[Dave]

Dont cut all the way through it. finish the edge with a file or disc grinder...

Finally got around to cutting the box cam.  I ended up casting a chunk of 2.5\" dia aluminum to make a filler piece to keep the halves together so I could cut right through (wood would also work, but I had a bunch of scrap ends of Al around and wanted to try it).  Since I drilled and tapped at this stage for locating in the brass tube later on, it\'s easy to screw into the filler.  30 minutes later, hot off the CNC:



I advanced the eject timing about 5 degrees based on some posts here.  We\'ll see if that helps any.

The barrel pack is also underway, but I have no photos of that.

Good job shred!!  I too have experimented with cam slopes; i.e.: using a steeper angle at first for the feed cycle, then lessening it in the final approach....anything to make it smoother, with less effort to crank.  The increase on the ejection cycle works good too, so keep experimenting and posting here.  I lay these cams out on my MasterCam and then just tweak the profiles.

Some more progress-- spent a long time faffing around making the breech casing, but it\'s done and looks to be correct with only one mistake that\'s well hidden by the frame rails (for anybody else that\'s not used to machining thin-walled tube-- check out how the model steam boiler people do it; lots of good stuff there).  



I think the fixing screws may be are a little long.  :lol:

One question on soldering-- the plans call for \'silver soldering\' the rails to the casing.  Do they mean proper silver-soldering or will a good soft-solder like Brownells Hi-Force 44 work?

I used Brownells Hi-Force 44 for all my soldering on my gun. Worked ok for me

A few weeks worth of progress:

Carrier Block-- I went with 12L14 steel because 3\" brass is nutsy $ these days.  I spent a while worrying about drilling .281 holes that deep without them wandering, but in the end they turned out fine. I CNC-ed it in the vise, flipping once.



Test-fit:



Then on to the nuts and main shaft:

Looks great so far. I am working a lot slower than you but I am not a machinist so there is a lot of learning as I go.

[quote name=\"50BMGBOB\"]Looks great so far. I am working a lot slower than you but I am not a machinist so there is a lot of learning as I go.[/quote]
Thanks..  I\'m no machinist either, but I\'m learning, one cut at a time  :lol:

Shred,

You won\'t happen to still have that G-code for your Box cam and bows laying around some where would you....wink, wink

Matt

I have them in backup files somewhere, since they\'re from a few PCs back.   I can post them here once I run across them again.  It\'s for a Tormach & 4th Axis and I\'ve not verified the end result with a working gun yet  FWIW, I offered to sell some extra bows a while back but got no interest.

I\'m running Mach 3 with a home brew CNC RT. I would like to be able to get most of the parts loaded up here for cnc. Someday won\'t mind figuring out how to cut the gears instead of throwing out $100 for a set. Might help bring in some new people if we could provide some G-code files for parts. I am a beginner CNC guy but like to learn more on that also.

Matt

[Dave]

Any updates Shred? Care to post some info on your cnc stuff? Im gathering all that I can, with the hopes of making a cnc mill....

I\'ve been working on my RG gun for a year now and have the cam box to he point of needing the slot cut. I have a homebrew cnc and almost have my 4th. axis done. I would really love to get the G-code for the cam also.

[Dave]

You may try Jerry or Cutter in the rgg forum, he is a good machinist and advertising cnc programing there...

Thanks, I\'ll give them a try

I found some G-code, but unfortunately my parts notebook is lost, so I make zero guarantees this will not try to mill the cam track into your machine table, or attempt to drill for oil in your shop or any other malfeasance.


I do remember it ran really slow since I was babying things due to the non-rigid setup. I also think either I had a solid insert in the tube I was cutting the cam into or didn\'t cut through quite all the way. There was also tailstock support. Other things I vaguely remember-- my 4th is on the left side of the table. IIRC the cam timing is different than the RG document by a little as per some advice I received (maybe even here) to help with extraction or ejection. The bolt extractor slot will need finishing. The mounting points match my casing, not necessarily the RG plans.

 

[attachment=9856:BoxCam3-stl2.nc-id=617.txt]

[quote name=\"shred\"]I found some G-code, but unfortunately my parts notebook is lost, so I make zero guarantees this will not try to mill the cam track into your machine table, or attempt to drill for oil in your shop or any other malfeasance.

I do remember it ran really slow since I was babying things due to the non-rigid setup.  I also think either I had a solid insert in the tube I was cutting the cam into or didn\'t cut through quite all the way.  There was also tailstock support.  Other things I vaguely remember-- my 4th is on the left side of the table.  IIRC the cam timing is different than the RG document by a little as per some advice I received (maybe even here) to help with extraction or ejection.  The bolt extractor slot will need finishing.  The mounting points match my casing, not necessarily the RG plans.[/quote]

I sure would like to know what the cam timing difference is. I just plotted the toolpath per the plans, but I haven\'t cut the slot yet.