Go Back   The AK Files Forums > General Forums > Gunsmithing & Build It Yourself

Reply
 
Thread Tools
Old 09-17-2012, 01:01 AM   #1
gesundheit
Member
 
AKaholic #: 162427
Join Date: May 2012
Location: In a van by the river
Posts: 342
Default Making perfect receiver trunnion holes

I have been wondering about how to make receiver trunnion holes that are perfect circles instead of parabolic circles.

The usual workflow involves marking trunnion holes with a trunnion hole locator like this (The inherent design of this tool does not render itself to precise marking of trunnion hole and that is why 5/32" drill bits are used as it is expected to be off by a little bit)



Then using centerpunch to estimate the hole location then using a 5/32" drill to make the hole and then egging the hole to fill up the trunnion's hole.

Problem

The problem with this is that the center punch will most likely not be in exact center and then the hole needs to be dremeled to fill the drilled.

My question is there another way to drilling trunnion holes that is more precise?
gesundheit is offline   Reply With Quote
Old 09-17-2012, 01:12 AM   #2
AKBLUE
Curio & Relic
Bronze Contributor
 
AKaholic #: 5035
Join Date: Dec 2005
Location: Hilliard, Ohio
Posts: 14,853
Default

Use the drill press and trunnion securing method. Covered in a lot of the build tutorials.

You use a bolt mechanism or other type jig that holds the trunnion squarely under the drill press., position the trunnion rivet location under the drill press & run the bit squarely into the trunnion hole. Then raise the drill press head ans sip the receiver over the trunnion and dril the hole.

example here>

http://www.arizonaresponsesystems.co....shtml#anchor2
AKBLUE is online now   Reply With Quote
Old 09-17-2012, 07:19 AM   #3
couch commando
Banned
 
AKaholic #: 161850
Join Date: Mar 2012
Location: Ks.
Posts: 641
Default

curtis builds this tool set for finding and drilling rivet holes, I believe it costs $65. Well worth the money.
couch commando is offline   Reply With Quote
Old 09-17-2012, 08:10 AM   #4
ironbike
Veteran Member
 
AKaholic #: 156771
Join Date: Mar 2011
Location: in your moms welding shop
Posts: 1,363
Default

i own,,and reg, use both tools ,,,if the trunnion,,,f or r is in the proper place ,,,and you carefully use a spring loaded self strikeing center punch,,,followed with a center drill ,,then drill ur final hole ,,the pliars work just fine ,,,and soemtimes the setup with the other tool is about the same time ,,,,just my experiance with both,,,,,surely u can eyeball the center of such a small scribed hole ?,,,lol
__________________
For a wounded man shall say to his assailant,
'If I live, I will kill you. If I die, You are forgiven.'
Such is the rule of honor.
ironbike is online now   Reply With Quote
Old 09-17-2012, 09:28 AM   #5
gunplumber
Arrogant Bastard
 
gunplumber's Avatar
 
AKaholic #: 328
Join Date: Nov 2003
Location: Surprise, AZ
Posts: 4,105
Default

All spiral flute drill bits will drill oblong holes. This is the nature of the beast and why drill are usually .0015 smaller than the hole they make. A straight flute bit works better.

Lower hardness bits or dull bits will tend to walk more than hardened (cobalt, tungsten carbide) bits.

My holes are perfectly round exactly where I want them because I use a carbide endmill and have the receiver tightly clamped. My holes are slightly undersize to the rivet. After deburring the back of the hole and tightly clamping the receiver to the trunion, I can chase the holes. Any variation between the receiver and trunion are evened out in this process. chase hole, install rivet. Chase hole, install opposite rivet.

But if you are trying to get your dull, HSS bit through a manually retained receiver, you will have poor results. You cannot get good results using crappy materials. If your drill bit does not raise a chip in a few rotations, it is useless and continuing to spin it against the receiver is just going to make it hot and useless.
__________________
T. Mark Graham, Master Gunsmith
Arizona Response Systems, LLC
gunplumber is online now   Reply With Quote
Old 09-17-2012, 09:33 AM   #6
gunplumber
Arrogant Bastard
 
gunplumber's Avatar
 
AKaholic #: 328
Join Date: Nov 2003
Location: Surprise, AZ
Posts: 4,105
Default

btw, I used to try to make the hole marking method luike the pliers work, but It ended up doing more work and worse results. All you need is something that will hold the trunion unmoving relative to the drill. You don't even need to drill all the way through, you can use a starter to mark the holes and drill by hand later, but if you have a drill press anyway, why not eliminate the human variable.

These rivet location markers from theyardstore.com have a spring-loaded punch that one can smack to mark after the other side finds the hole. Problem is they are made more for for two pieces of sheet metal than a more 3D object.

http://www.yardstore.com/browse.cfm/4,4191.html
__________________
T. Mark Graham, Master Gunsmith
Arizona Response Systems, LLC
gunplumber is online now   Reply With Quote
Old 09-17-2012, 11:22 AM   #7
gesundheit
Member
 
AKaholic #: 162427
Join Date: May 2012
Location: In a van by the river
Posts: 342
Default

So this is what I have learned thus far:

1. Use straight flute carbide bit
2. Clamp the receiver down so that there is no movement during the drilling
3. Eye ball the center punch to land in the perfect center of trunnion hole locator tool
4. Use Curtis tool (I have been told by another builder that this tool is not good and folks get better results without it).

This is what I need to figure out "Use the drill press and trunnion securing method". I have seen a couple of videos on youtube where this method is used, but what I have yet to find out is how to secure the trunnion to the drill press.
gesundheit is offline   Reply With Quote
Old 09-17-2012, 11:32 AM   #8
gunplumber
Arrogant Bastard
 
gunplumber's Avatar
 
AKaholic #: 328
Join Date: Nov 2003
Location: Surprise, AZ
Posts: 4,105
Default

Quote:
Originally Posted by gesundheit View Post
So this is what I have learned thus far:

1. Use straight flute carbide bit

not necessary - cobalt is fine. Spiral is fine, but straight flute is superior (no walking) and carbide is better than cobalt. Problem is, carbide is 3x the price of cobalt. But HSS is only good for 1-2 holes. Even my cobalt I get a bout 1 receiver before it goes to the drill doctor for resharpening.


2. Clamp the receiver down so that there is no movement during the drilling
3. Eye ball the center punch to land in the perfect center of trunnion hole locator tool
4. Use Curtis tool (I have been told by another builder that this tool is not good and folks get better results without it).

This is what I need to figure out "Use the drill press and trunnion securing method". I have seen a couple of videos on youtube where this method is used, but what I have yet to find out is how to secure the trunnion to the drill press.

A drill press mill vise. It is a flat vise that clamps to the drill press table using those funny slots.
my comments in red
__________________
T. Mark Graham, Master Gunsmith
Arizona Response Systems, LLC
gunplumber is online now   Reply With Quote
Old 09-17-2012, 12:47 PM   #9
ott1
Senior Member
 
AKaholic #: 157734
Join Date: Jul 2011
Location: La Verne
Posts: 940
Default

It's similiar to what I do.

http://forums.gunboards.com/showthre...ing-tools-here
ott1 is online now   Reply With Quote
Old 09-17-2012, 02:47 PM   #10
jdoming728
Senior Member
 
AKaholic #: 157837
Join Date: Jul 2011
Location: In the Southwest...
Posts: 783
Default

The Jig from Guns and things and the one from Curtis is the best one I think and to date I have never had to egg or adjust any of the holes I have drilled for front trunnions with these Jigs...
jdoming728 is offline   Reply With Quote
Old 09-17-2012, 03:06 PM   #11
Blacksmith
Curio & Relic
 
AKaholic #: 10051
Join Date: Dec 2007
Location: AZ
Posts: 4,034
Default


__________________
"I reject any form of government in which the opinion of the village idiot is given the same weight as the opinion of Aristotle"
Blacksmith is offline   Reply With Quote
Old 09-17-2012, 03:41 PM   #12
a-kmanator
Resident Parts Hoarder
Bronze Contributor
 
a-kmanator's Avatar
 
AKaholic #: 7569
Join Date: Feb 2007
Location: 100 yards to your right...If you can read this..You're in Range...
Posts: 4,114
Default

Quote:
Originally Posted by gesundheit View Post
Then using centerpunch to estimate the hole location then using a 5/32" drill
The problem with this is that the center punch will most likely not be in exact center and then the hole needs to be dremeled to fill the drilled.
precise?
Use a transfer punch right thru the pliar tool not a center punch. Will increase hole placement accuracy 100% ...no more "Eyeballing" the center.
http://www.victornet.com/report/Tran...nches/823.html
a-kmanator is online now   Reply With Quote
Old 09-17-2012, 04:11 PM   #13
Dan FS71
ΑΩIs
Bronze Contributor
 
Dan FS71's Avatar
 
AKaholic #: 54259
Join Date: Aug 2009
Location: USA
Posts: 4,672
Default

Quote:
Originally Posted by Blacksmith View Post

This is the method I use too. Quick dirty and effective.

If you are they type that checks to see if the door is locked 12 times after you just locked it.

Indicate the hole with a co-ax before you throw your endmill en you mill. An extra step will get you with in the 10z (10 thousands or an inch) Which is way more than necessary but many like to split rch-es for the fun of it.
__________________
The futher & futher I go, the more I realize I'm lost. I've made peace with that.

================================================== =========================
The same administration who put "Assault Rifles" into the hands of Murderous Drug Cartels now seek to take them from you.
================================================== =========================
How is that for common-sense Change?

Old Testament Retribution. --- Gunplumber Style --- Served Here
Dan FS71 is offline   Reply With Quote
Old 09-17-2012, 08:15 PM   #14
gesundheit
Member
 
AKaholic #: 162427
Join Date: May 2012
Location: In a van by the river
Posts: 342
Default

Thanks all y'all for some really great ideas.

I will show BlackSmith's pictures to a friend of mine to see if I can replicate this on my cheap setup or if I need to upgrade. In the meanwhile, if anyone knows the most basic system that emulate this setup, I am all ears.
gesundheit is offline   Reply With Quote
Old 09-17-2012, 08:54 PM   #15
Blacksmith
Curio & Relic
 
AKaholic #: 10051
Join Date: Dec 2007
Location: AZ
Posts: 4,034
Default

Quote:
Originally Posted by gesundheit View Post
Thanks all y'all for some really great ideas.

I will show BlackSmith's pictures to a friend of mine to see if I can replicate this on my cheap setup or if I need to upgrade. In the meanwhile, if anyone knows the most basic system that emulate this setup, I am all ears.
http://www.use-enco.com/CGI/INSRIT?P...&PARTPG=INLMK3
http://www.use-enco.com/CGI/INSRIT
http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32
With a drill press, these and a center cutting 4 flute end mill is all you need.
The stuff from ENCO is top notch. But if you want to save money, try Harbor freight.
Or you can do what I did and upgrade from a Drill press to one of the Harbor freight Mini mills.
Don't let the name fool you, the Mini mill is a beast. You can even mill out a receiver on it if you put your mind to it.

Edited to add:
For some reason the second link is not working. If you scroll down from the table link, it's the clamping set second down under "May we also suggest"
__________________
"I reject any form of government in which the opinion of the village idiot is given the same weight as the opinion of Aristotle"

Last edited by Blacksmith; 09-17-2012 at 09:08 PM.
Blacksmith is offline   Reply With Quote
Old 09-18-2012, 12:08 PM   #16
gesundheit
Member
 
AKaholic #: 162427
Join Date: May 2012
Location: In a van by the river
Posts: 342
Default

Thanks Blacksmith. This is really useful. After I get this setup, I can rest assured that the rivets are sitting on top of perfect holes
gesundheit is offline   Reply With Quote
Old 09-19-2012, 11:20 PM   #17
jasonixo
New Member
 
AKaholic #: 160287
Join Date: Jan 2012
Location: Buford, GA
Posts: 4
Default

Pay close attention to the tips on the center punches you purchase- make sure they are actually centered.
jasonixo is offline   Reply With Quote
Old 09-19-2012, 11:41 PM   #18
RevRon
Hill Jack
 
RevRon's Avatar
 
AKaholic #: 156404
Join Date: Mar 2011
Location: Southern Ohio
Posts: 1,972
Default

Quote:
Originally Posted by Blacksmith View Post
Can you provide more info on the trunnion holding set up you have there? I'm assuming you made it yourself.
__________________

RevRon is offline   Reply With Quote
Old 09-20-2012, 04:10 AM   #19
Blacksmith
Curio & Relic
 
AKaholic #: 10051
Join Date: Dec 2007
Location: AZ
Posts: 4,034
Default

Quote:
Originally Posted by RevRon View Post
Can you provide more info on the trunnion holding set up you have there? I'm assuming you made it yourself.
The clamping kit, KANT twist clamp and Mill was purchased from Harbor freight and ENCO. I just put the pieces together.
See post #15.
__________________
"I reject any form of government in which the opinion of the village idiot is given the same weight as the opinion of Aristotle"
Blacksmith is offline   Reply With Quote
Old 09-20-2012, 10:20 AM   #20
RevRon
Hill Jack
 
RevRon's Avatar
 
AKaholic #: 156404
Join Date: Mar 2011
Location: Southern Ohio
Posts: 1,972
Default

Quote:
Originally Posted by Blacksmith View Post
The clamping kit, KANT twist clamp and Mill was purchased from Harbor freight and ENCO. I just put the pieces together.
See post #15.
I need to get some of those clamps.

How about this?

DSC01570
__________________

RevRon is offline   Reply With Quote
Old 09-20-2012, 02:05 PM   #21
Blacksmith
Curio & Relic
 
AKaholic #: 10051
Join Date: Dec 2007
Location: AZ
Posts: 4,034
Default

Quote:
Originally Posted by RevRon View Post
I need to get some of those clamps.

How about this?

DSC01570
This is what you need.
http://www.use-enco.com/CGI/INSRIT?P...&PARTPG=INLMK3
I have the harbor freight version of this same kit but it did not come with those handy looking wrenches. With this kit and a little imagination there is nothing you can't clamp to the Mill table.
__________________
"I reject any form of government in which the opinion of the village idiot is given the same weight as the opinion of Aristotle"
Blacksmith is offline   Reply With Quote
Old 09-20-2012, 03:04 PM   #22
RevRon
Hill Jack
 
RevRon's Avatar
 
AKaholic #: 156404
Join Date: Mar 2011
Location: Southern Ohio
Posts: 1,972
Default

Quote:
Originally Posted by Blacksmith View Post
This is what you need.
http://www.use-enco.com/CGI/INSRIT?P...&PARTPG=INLMK3
I have the harbor freight version of this same kit but it did not come with those handy looking wrenches. With this kit and a little imagination there is nothing you can't clamp to the Mill table.
Thanks for the Link. Enco is about $20 cheaper then harbor freight. Who would have thought?
__________________

RevRon is offline   Reply With Quote
Old 09-20-2012, 07:07 PM   #23
Blacksmith
Curio & Relic
 
AKaholic #: 10051
Join Date: Dec 2007
Location: AZ
Posts: 4,034
Default

Quote:
Originally Posted by RevRon View Post
Thanks for the Link. Enco is about $20 cheaper then harbor freight. Who would have thought?
ENCO is a good outfit. It seems like every time I put an order in with harbor freight I only receive about half of it along with an email stating that the other half was discontinued or out of stock. So far with my dealings with ENCO, I have received 100% of what I order. they have a great selection of end mills and reamers as well. Good stuff.

BTW
That Kant twist clamp is a must have as well. Without it, the end mill will shoot the receiver across the shop.
__________________
"I reject any form of government in which the opinion of the village idiot is given the same weight as the opinion of Aristotle"

Last edited by Blacksmith; 09-20-2012 at 07:12 PM.
Blacksmith is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT -5. The time now is 04:51 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.