# Sten tube



## Karl_T (Oct 14, 2014)

This is my Sten receiver tube project. For those not aware, you can buy pieces of old cut up military weapons and rebuild them into semi-auto rifles. In nearly all cases, the receiver is cut up and destroyed on these parts kits. Here's info on the Sten: http://en.wikipedia.org/wiki/Sten.  BUT FIRST, you need the project to do the project. I just finished installing a servo motor to drive my index head. Here's everything mounted on the table:


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## Karl_T (Oct 14, 2014)

This is on my Excello 602 CNC knee mill with a Camsoft control. I first reconfigured the control to have a 4rth axis and found the number of encoder counts for one revolution and the number of counts of backlash. With this poor man's setup, the backlash is HUGE - 150 encoder counts - too much for the CNC control to handle. I'll have to add in a Gcode line every time direction in reversed


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## Karl_T (Oct 14, 2014)

Then I found a .pdf print on the web of Sten receiver. First I drew it up with degree of revolution on the 4rth axis. When I got to the cocking slot, I seen that won't work. There are arcs to be cut and you can't have different units on one axis X in inches, A in degrees and get the correct arc. So i re did the control for a 1.5 inch tube to get motion on A in inches of surface movement. At this point I have a first draft of the receiver in Draftsight X64. The white lines are the outline to be cut, blue lines are quadrants of the tube laid out flat (gives reference for the drawing work), the green lines are the tool path for a 1/4inch endmill. I see mistakes in the .pdf, need to work them out, also some work will need to be cut with a 1/8 endmill. I'll lay this out as another layer on the drawing


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## sd624 (Oct 14, 2014)

Karl_T I've built a handful of SAS in the past and have two going right now on the workbench. I've just printed out the templates and glued them to the tubes and cut the out by hand on the BP. Your setup looks sweet and will make doing the tube a walk in the park. Keep the pics coming.


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## ScrapMetal (Oct 14, 2014)

I've been contemplating a Sten build myself so will be watching your progress.

Thanks,

-Ron


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## Karl_T (Oct 15, 2014)

OK, today's job...   Finished checking drawing against actual parts and made some updates. Then I saved only the 250EM layer from Draftsight to a .dxf file. I opened NCplot and converted from .dxf to Gcode. I see the NCplot webpage now has a free .dxf to Gcode converter.   Now I have a Gcode program to test on the mill. I'll order tubing later today and test the code on the mill...................   EDIT I can't get paragraphs to work in this forum - everything runs together - how to I separate my text? I put in ... today.  Karl


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## Karl_T (Oct 15, 2014)

One more tiny step I'll mention. MEconsultant says to run my 2 flute HSS endmill at 1000 RPM 2.5 IPM  I'll plunge at 0.5 IPM


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## JimDawson (Oct 15, 2014)

Karl_T said:


> EDIT I can't get paragraphs to work in this forum - everything runs together - how to I separate my text? I put in ... today.  Karl



I just tested it.

Seems to be working now

The admins are working on the site, so a few strange things have happened.

Sorry for the inconvenience.


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## Karl_T (Oct 15, 2014)

JimDawson said:


> I just tested it.  Seems to be working now  The admins are working on the site, so a few strange things have happened.  Sorry for the inconvenience.



 Hmmm, FNG doing something wrong. 

I just edited in paragraphs in above post. it didn't take, ran it all together again. 

 Karl  Edit, I'm just hitting enter  twice to make a paragraph.


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## JimDawson (Oct 15, 2014)

Karl_T said:


> Hmmm, FNG doing something wrong.
> 
> I just edited in paragraphs in above post. it didn't take, ran it all together again.
> 
> Karl  Edit, I'm just hitting enter  twice to make a paragraph.




I just edited your post above, it seemed to work OK.  I also am hitting enter twice to make a paragraph.

Maybe your browser?  I am using Google Chrome.  Not sure what the problem is, keyboard issue?


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## Karl_T (Oct 15, 2014)

JimDawson said:


> I just edited your post above, it seemed to work OK.  I also am hitting enter twice to make a paragraph.  Maybe your browser?  I am using Google Chrome.  Not sure what the problem is, keyboard issue?



Maybe FNGs aren't allowed  access to the 'ENTER' key till they have 1000 posts???http://www.hobby-machinist.com/images/smilies/rofl-smiley-gif-800.gif   I'll live with it, make short posts and get my post count up.

  Karl

  PS Looks like I couldn't do the smile right either


PPS, changing AWAY from the wsiwig editor solved this issue


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## JimDawson (Oct 15, 2014)

Karl_T said:


> Maybe FNGs aren't allowed  access to the 'ENTER' key till they have 1000 posts???http://www.hobby-machinist.com/images/smilies/rofl-smiley-gif-800.gif   I'll live with it, make short posts and get my post count up.  Karl  PS Looks like I couldn't do the smile right either



Try playing with the [SUP]A[/SUP]/A and the [SUP]A[/SUP]xA buttons in the upper left of the of the message box.


Also. go to Settings, General Settings and scroll down and make sure the WYSIWYG editor is turned on.


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## Karl_T (Oct 19, 2014)

Had to farm all week so only a little progress here...

made a plug for each end of the tube to match the ID and then have a shoulder. On the drive end made a couple parts to tighten the tube in place, other plug just has a center for the tail stock. Then almost finished indicating in before the football games started.


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## Karl_T (Oct 26, 2014)

My real job keeps getting in the way. I cut up the old ones today. Still have to grind out the bits and pieces of the old tube. I decided to have this all done before running the CNC so i can double check the part fits perfectly. Won't have time to do more till the weather gets nasty.


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## Karl_T (Oct 27, 2014)

just a small step this morning before the real job calls...

The part on the extreme right in the previous post is the trunion with receiver tube still welded on. Need to remove that receiver scrap and have the trunion correct OD to fit the new tube. I decided to do this first so the fit can be checked when I turn the new receiver tubes to size.

The secret to this job is soft jaws. Install them first then turn the jaws them self to size. Then your part will run perfectly square and true. I made my soft jaws the hard way - this old chuck doesn't have reversible jaw face. I put another soft jaw in the picture so you can see the scroll teeth cut in the AL.


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## Karl_T (Oct 29, 2014)

Got part 1 today...

All the work on CNC is getting part 1 right. Then just push the green button for the next 10,000.

First I show boring the ID. To conform to federal laws, a full auto bolt cannot be able to be installed in the weapon. The common way to do this on tube guns is to use thicker wall tubing and only bore out to fit other parts like the trunion and return spring cap in this case.

Then here's the CNC mill running. The real project was installing a servo motor on an index head.

Finally I test fit a rifle together. Found the program needs one extremely small edit.

This tube is original design. I'll also make a couple Indy Ordnance design to use their bolt and fire control group design.

I'll close this thread out at this point. When spot welding together, I'll start a project on how to build your own spot welder and show welding of Stens.


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## Karl_T (Nov 1, 2014)

I was going to close this thread.... But, just had to show this little step.

Bored out the scrap tube out of the back of the receiver this morning. Most just use a die grinder or dremmel. Did one this way and it looked terrible to a machinist.

So I made the below setup and bored it out. Worked slicker than snot on a greased glass door knob.


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## Karl_T (Nov 2, 2014)

Got them all test fit


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