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#9732 Another new guy with first questions.

Posted by Swarfmonger on 27 July 2020 - 10:58 PM

Sorry about that, I thought I did. Let’s try again...

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#9736 Another new guy with first questions.

Posted by Swarfmonger on 29 July 2020 - 06:22 PM

I silver soldered it (Hi Force 44) and added an additional 2-56 flat head for added strength but the latter is probably unnecessary. I pretty much built it on the fly but if you have any questions as to specifics I’ll do my best to answer them. One thing I would definitely recommend is match drilling the top cover and breech casing with a 3/16” followed by a 1/4” endmill. The small hole you see at the end of the plunger is for inserting a small punch so the knob can be loosened/tightened.

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#9735 1/2” steel ball source?

Posted by brk on 29 July 2020 - 12:01 AM

I also added a slot down the length of the acme screw and made a brass finger to engage it to keep it from turning.  Here are a couple photos, one with a flash to help show the groove.

 

I have a thrust bearing under the brass piece that is under the finger.

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#9698 My RGG progress

Posted by Swarfmonger on 26 June 2020 - 06:16 PM

I finally got back on my Gat project after a 3 week hiatus so I could “do the things I actually should be doing” that Mr. Moore mentions in his plans. I started this about 5 months ago to help deal with COVID boredom when I wasn’t at work and hit a minor breakthrough yesterday.

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#9389 What's wrong with my thinking?

Posted by Sparky_NY on 09 January 2020 - 02:31 PM

I will follow your instructions.

 

It is not obvious to a newbie  that such experienced techniques are so critical. 

 

If I understand your comments, I drill the hole and then ream prior to  proceeding to the next hole (no movement of the work). It appears that a relatively short length reamer will be required to preclude  large movement  on the Z axis. My DRO is one of the Chinese version that displays position to 5 decimal places so the hole location should be accurately placed.

Not reamed, bored with a boring head.   A reamer will still follow a drilled hole that is not true.    A boring head will true up any walking off center the drill bit did which is pretty much guaranteed to happen with deep hole drilling like this.

 

In general terms,  when holes need to be very accurately sized and exactly on location,  boring is the accepted method.   Drilling a starter hole to get most of the meat out is how to start of course,  just leave enough material for the boring bar to true things up.

 

I went through the same problems you are experiencing.    If I recall correctly, Cutter is the one that suggested boring the holes as the best method.    He was absolutely correct !   The hole positions were orders of magnitude improved.

 

Making the bolt carrier in 2 pieces also helps a lot,   the depth of the holes are much less than one piece.   Although its 2 parts instead of one, its actually easier that way with better results.


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#9292 RG-G food for thought

Posted by barrelguy on 10 November 2019 - 05:15 PM

I am a machinist with 60 years experience in the trade who started a couple of guns 3 years ago.  With my machining experience I decided I didn't like the idea 

of silver soldering or welding these parts together.  I used dowel pins and screws instead.  I have disasembled these guns at least 100 times in the last three years

to re-work, modify, tweak, or re-engineer the parts to make the gun work.  I couldn't have done that with a soldered up gun.

     Just food for thought.


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#7795 D&E Carriage

Posted by Roller on 28 August 2017 - 10:59 PM

Attached File  IMG_20170727_085606.jpg   295.38KB   4 downloadsupdate on project.


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#9705 RGG Drum Magazine - Improvements?

Posted by brk on 01 July 2020 - 03:37 AM

I machined my bolts for the extractors from Gbull and found a little interference with the drum and the feed lips I made.  Before the extractors were in the bolts, the bolts all cleared the magazine and feed lips, but with them installed, there was just a little interference. I missed this when I drew up the feed lips.  The magazine would have needed just a little clearance with or without the feed lips. I had to put a small radial (or arc) cut in the lower 1/16" sheet brass cover of the magazine and then add a 1/16" x 1/16" relief in the feed lips.  I could have gotten by with less clearance, but did not want to do it twice and figured a little extra clearance here wouldn't hurt anything.

 

Extractors from GBull were very accurate to each other but were a little off from the .dxf file. I did have some extractors from Cutter from years ago when I bought the bolts  and forgotten I had them (actually I had misplaced them).  Cutter's matched the dxf but varied a little more than Gbulls.  Gbulls didn't vary more than about .001"  He said he had them wire EDM, Cutter's were milled.  I checked them out on a optical comparator I made a dummy bolt and made a few samples on the cuts/cross hole for the extractors. If I put the cross hole on location for the heel of the extractors, Gbulls extractors were about .067" from the face of the bolt to the underside of the extractor.  Cutters were much closer to .055".  I decided to move the cross hole toward the rear and used Gbulls since his were already hardened.  I figure I could use Cutter's as spares and may just need to take a little material off the heel to get those to the.055" from face of the bolt to underside of extractor.  This way gave me the most options with extractors from two sources.

 

I advise anybody that is going to fit extractors, make a dummy bolt first to get the setup right and tweak to get what you want. I had a total of 23 bolts and got them all machined without scrapping any.

 

Here are some pics

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#9669 Worst part of machining an RGG?

Posted by Cutter on 12 June 2020 - 12:27 AM

For me,  the easiest approach to the cocking switch is this.
 Using 1/2 diameter material turn the .250 shank to length
then mill the flat back to the shank then put the pick up slots in
and cut the angle on top. No angle on this image

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#9624 Lockdown

Posted by Cutter on 31 May 2020 - 02:54 PM

ISOLATION 

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#9609 Non Elegant solution

Posted by Cutter on 24 May 2020 - 02:57 PM

10-4

 

Mr X

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#9581 Server issue

Posted by drhardin on 20 May 2020 - 03:08 PM

Thanks for all you do.


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#9576 Carrier block counter bore

Posted by Cutter on 19 May 2020 - 10:46 PM

With the two piece carrier. I would have to buy another piece of brass, I can only get 1/2 the carrier out of the new piece that I have ready to go. Plus I have to buy an additional hex bushing part for the extra 2 press fit sockets. The counterbore I was using was a 3 flute 27/64 .4219 (within tolerance) but bored a .434 hole, opps your fired! Curious why would an endmill produce a better hole? How would a shop do this with strict adherence to the print without f-up? I was a machinist 40 years ago with some schooling, and only 2 yrs experience. At that time all the work went to Japan, and shops wanted 5-10 yrs experience, they could get it easily. So I went another direction, but I kept my tools. I knew I'd finally get back to it.

 

 

Drilling removes material , Boring straightens the hole, Reaming is for size.
This process is a standard machine shop practice.
Normally a counter bore is made for shallow depths. The counter bore will
follow the hole , so if the deep hole is not straight the uneven pressure will cause
the oversize condition. 
A boring bar or Swarfmonger’s method is best.

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#9504 Lockdown

Posted by Cutter on 26 March 2020 - 06:34 PM

My wife says gardening is good for stress

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#9432 Semi m60 build

Posted by Dave on 01 February 2020 - 07:00 PM

More pics

 

 

 

 

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#9420 What's wrong with my thinking?

Posted by Larryx on 29 January 2020 - 12:11 AM

I will use the steel bar. It is drill rod from the drops of a company that makes of all things, drills. 


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#9264 Chris’ build.

Posted by maccrazy2 on 12 October 2019 - 10:02 PM

Ok. I got these all sorted out. I made 3 of them so far. The last one came out better than the first two. I ended up using a 3/8 endmill instead of a boring bar to finish out the holes and was much happier with the surface finish. I’m going to remake the first 2 so they all have the same barrel tennon size.
I started with.400 and it’s fine but the material is quite thin between the counterbore holes for the barrel mounting holes. I tried.385 on the second and the material between the holes was more stable but I got a little bit of chatter when boring the holes. Both of them displaced a lot of metal at the surface when drilling the holes requiring more deburring than I expected. I drilled pilot holes and finished with endmills on last one and it came out much better.
In retrospect, I should of made these first so the holes would be fully supported going into the aluminum fixture holding the part. I made the bolt carriers first so the holes are .420 and it caused a burr I had to remove on the barrel plate in all the barrel holes. Not a big deal but one more step that could of been avoided.

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#9258 FInding pictures

Posted by Cutter on 03 October 2019 - 12:24 AM

This is what I did.
The adapter sets on top the frame with a hinge
on the left side and a latch on the right

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#9113 Entertainment!

Posted by Cutter on 23 June 2019 - 03:16 PM

Machinist life

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#9077 New Bolts

Posted by Cutter on 12 June 2019 - 10:17 PM

Cam is in and functioning.
I’ll try popping a blank tomorrow. 
 

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