THROUGH KEYWAYS IN BARREL BUSHING

[SHARPSSHOOTER5090]

Does the keyways for the barrel guide in the barrel bushing have to be blind or can they be thru broached. What purpose does the blind keyways serve? I broached them thru on the 2 barrel bushings I made and was going to drill into each keyway from the outside and press in a pin to form the blind stop but is that necessary?

Thanks

SS

[Michael J]

I just looked at my bushing i bought from APEX (i think a wiselite bushing), and the stop regulates the distance the barrel guide goes in. There is a gap between the end of the guide, and the booster thingy. The barrel guide is not meant to actually touch the booster. So the pin, or some other method of stopping the barrel guide is required. It looks like the slots end about 8mm from the end of the bushing, but this is just a "guesstimate" as i can't fit my ruler in there.

I think i understood what you're talking about, but if my reply makes absolutely no sense, than just disregard it !

[mattcdavis]

I built my own bushing too. I also left the slots all the way through. The problem is that this allows the barrel bushing to go to far forward and not let you put the barrel back in the gun when changing out the barrels! To fix mine I just put a tack weld in the correct place along one of the slots, but your pin should work great too!

[METALSMITTY45]

New to this site ,found some very nice info here.I just finished making my repair bushing using the print I found here and I cut the keyway/spline stops with the woodruff cutter per the print.

I ground a high speed tool shaped like both size slots and using a boring bar to hold it mounted in my lathe I broached the slots .You have to take light cuts and it took about two hours to do all four slots.

You can use a four jaw chuck as an indexer an inicator as a return referance.Broaching in the lathe is something I've had to do before in a pinch and is fairly reliable.

I'd be happy to explain in better detail if anyone is enterested plus I have some photos as well.

[mattcdavis]

I tryed to do mine in the lathe but my lathe and table are just too small I think? I had a really neat setup though! I used the handle from a broken craftsman breaker bar and some flat steel to make the handle and connecting rod assy. I just ended up doing initial cuts with a sawsall and finishing with a file. took hours! I would like to see the pics of your setup. I wish I had opted for the bigger lathe. But I hear thats what everyone says!

[Bil]

Yes,if it was possible,we would all be happy to have a bigger one! Larger lathe would be nice also! ---bil

[METALSMITTY45]

I have the pictures with set up info over on the Weapons Guild ,I couldnt get my user name to work over here but its IRON WORKER everywhere else.
Is photo bucket or other host the only way to post pictures here? I'll try to make up a how to tutorial on my method.

I made mine just like the print posted here ,used the proper size woodruff cutter inside and using a boring bar with a piece of tool steel ground to size,all you have to do is set the tool using the hieght adjustment on your tool post and take light maybe .005'' cuts until your to depth .

You use your carraige to traverse the cutter through until it clear into the woodruff slot,this is a old method that in a pinch to cut keyways .

The only thing I changed on the O.D. of the bushing where it enters the shroud is straight turned to press into the original bore pryer to welding.

The print here shows the original swaged bushing,but all other specs are correct.

It will probably be tonight or in the morning before I can get any pictures here,in the meantime take a look over in the MG42 build section on the weapon guild.

[johnnymg]

Anyone have a measurement for placement of the front bushing? I know the overall measurement from doing a search, however was wondering if someone had a measurement from front site mount, bipod stamped area or from the camming piece to locate the bushing without a completed receiver to use the overall length method?

Johnnymg

[METALSMITTY45]

I tok a measurement og my Yugo bushing stub before removal and it 17.750'' located from the inside shoulder where the barrel extension rest against to the rear face of the bushing.

Here are a few pictures of my bushing and the boring bar broaching tool.Basically the way I did my slots was :

1) do all lathe work turning etc.

2) using a #305 woodfruff cutter I cut four slots to depth per drawing on this site 90 degrees apart

3) using a 3/16'' extended length carbide endmill I milled four radial slots where the splines go,just shy of full
depth.

4)using my four jaw chuck in the lathe I placed my bushing in the chuck aligning the slots to the chuck jaws and indicate bushing true to lathe spindle.

5)Next I leveled the two horizontal jaws with and indicator and set my dial to zero on one jaw,this is now my indexer by merly moving the chuck 90 degrees each time and coming back to the zero on the jaw face will precisely index the bushing four times.

6)Now using a 5/8'' boring bar with a high speed tool steel bit ground to .236'' on one side and .177' on the other.I centered the bar precisely in the bore ,then using the hieght adjustment on my tool post I touched the bore.

7)Now lower tool about .005'' (use an indicator for tool movement) ,using plenty of tap free two cutting fluid traverse the bar by hand with the carriage handwheel until you stop in the woodruff slot.

8)Now raise tool up and with draw from bore,lower it and repeat until you clean up all of the radial slot,depending on how sharp and rigid your lathe is you may have to use the same hieght for several passes.

9)Once you have one slot cut,index chuck jaw 90 degrees until the preset indicater comes back to zero on the next jaw( I mounted my indicator on the cross slide)

10) your now ready to cut the second slot and repeat twice more,it took me about two hours to completely broach mine

11) remember three slots are .236' wide and one is .177'' wide,I used one tool and ground the cutting edge on both ends.

[METALSMITTY45]

Here are a few more pictures, I had to broach mine in reverse starting at the woodruff slot because I didn't want to crush the threads by chucking on them.
But ideally you need to broach from the bevel and stop at the woodruff slot,just wait and thread the o.d. last after broaching is better.

Initially I had the bushing mounted in my three jaw but got to thinking if I switched to the four jaw this would give me a means of indexing although you could use anouther method if you like.

I installed the bushing but I have not welded it in yet.

[mattcdavis]

Nice! Now that I see your cutter tooling I could probably make one that was similer. But that will be for the next project, cause I already finished this one! Great pics!

Bil......Yes we would all like a bigger one.....lathe that is!

[METALSMITTY45]

One thing I didn't mention is you do not need as much back relief on the tool bit,I had to do mine because I was starting the cut in the woodruff slot since I chucked it backwards to avoid thread damage.

What you do need is to copy very closely the form of a regular broaching tool,with good chip breaker and the sides at a right angle to the edge with little to no back relief .That way the tool will track correctly each consecutive pass.

You can see my chip breaker in this one and and it held up great taking the light cuts,you only have to go about .059'' deep per the drawing and pre cutting the shallow end mill passes helps lighten the cutter load.

[Michael J]

Thanks for the tutorial, i'll have to try this out on my bushing monday.

[42rocker]

METALSMITTY45
FNG ------ RIGHT-------

THANKS many times over for sharing this and the pics..

Might have to give this one a try.

Thanks Again

Later 42rocker

[METALSMITTY45]

Your quite welcome

Couple more tips:

1) Set up bushing in mill vice with threads up to cut woodruff slots as the shank will hit the bore if you try it on the bevel side.

2) Flip over and indicate bore of bushing back in to mill and use an extra length 3/16'' carbide endmill and touch bore wall and go about .057'' deep per side four slots ,I used the quill and plunged cut going several passes until reaching the depth.Be carful those long carbide endmill will flex and break easily.

3)You can still broach without the endmill cuts but it will take longer

My lathe is a Grizzly 12 x 36 G4003 and it had no problem doing this job.

4) Use low gear this will keep chuck as rigid as possible

5) Make sure the sides of the tool are perfect right angles to the cutting edge,this will aloow the tool to track in the same cut each time.

Here are a couple more pictures that show the set up ,shows my indicator referance,Use it to bring chuck jaw back to same mark each time you index,move the base out of the way while your cutting and slide it on the cross slide top surface.

[42rocker]

Always nice to find some of the good old stuff.

Later 42rocker