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Modulus Arms 80% Lower Jig Review (photo heavy) (Page 2 of 4)
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Originally Posted By PursuitSS:
I have been looking into adding Drill Bushings to this jig. I've found a source for Tungsten Carbide Drill Bushings and I can get bushings for the trigger and hammer holes that have an I.D. Of .154  Sharing is caring ... source and cost please? |
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Originally Posted By Paul:
Sharing is caring ... source and cost please? Originally Posted By Paul:
Originally Posted By PursuitSS:
I have been looking into adding Drill Bushings to this jig. I've found a source for Tungsten Carbide Drill Bushings and I can get bushings for the trigger and hammer holes that have an I.D. Of .154 Sharing is caring ... source and cost please? Here you go...Link |
"When trading bullets it is better to give than to receive"
"People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf." - George Orwell
"People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf." - George Orwell
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Originally Posted By Redshirted:
Maybe I missed the info somewhere but... Can this jug be used to complete the lower using just a drill press if you don't have a router? Thanks in advance for the help. No real reason to not get a router. The one they use in the instructions is 99 bucks on amazon. I just ordered it last week. You can always sell it when you are done. There was a jig and router in the EE a little while back. Sold really quick. |
I swear to God I'm going to pistol whip the next guy who says, " Shenanigans."
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Just did my first lower today with this jig. Used the router they recommend.
Went pretty well once I got the hand of milling with a router. One word of advice, make sure the end mill is tightened into the router well. Mine worked down a little and milled too deep in one spot. Will work fine though. |
I swear to God I'm going to pistol whip the next guy who says, " Shenanigans."
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Yes you can use this jig with just a drill press and no router.
You'll need an end mill/burr that is about 6 inches long (1/4" shaft and cut). Found a few on eBay for about $17. But, with that length on the burr, it does flex. You have to go very slow. I purchased a DeWalt hand router, and it's much easier. G. |
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Originally Posted By XJ:
The liver credit card is evil, and it must be punished
http://littlemachineshop.com/products/Images/480/480.4980.jpg Where did you buy from? Little Machine Shop? |
-Nemo me impune lacesset.
-Beware the fury of a patient man.
-Thousands and thousands of laws....All for just ten commandments.
-"alot" is not a word.
-Beware the fury of a patient man.
-Thousands and thousands of laws....All for just ten commandments.
-"alot" is not a word.
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Any reason to avoid this router
http://www.amazon.com/SKIL-1830-120-Volt-Combo-Router/dp/B004SKY73O/ http://www.amazon.com/SKIL-1830-120-Volt-Combo-Router/dp/B004SKY73O Wes |
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Originally Posted By Wangstang:
Any reason to avoid this router http://www.amazon.com/SKIL-1830-120-Volt-Combo-Router/dp/B004SKY73O/ http://www.amazon.com/SKIL-1830-120-Volt-Combo-Router/dp/B004SKY73O Wes That one is not variable speed. The slower speeds are better for the aluminum. This one is the recommended router, and the one I just used to complete a lower. Worked out pretty well. http://www.amazon.com/gp/product/B000ANQHTA/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1 |
I swear to God I'm going to pistol whip the next guy who says, " Shenanigans."
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Originally Posted By icrpdmeself:
That one is not variable speed. The slower speeds are better for the aluminum. This one is the recommended router, and the one I just used to complete a lower. Worked out pretty well. http://www.amazon.com/gp/product/B000ANQHTA/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1 Originally Posted By icrpdmeself:
Originally Posted By Wangstang:
Any reason to avoid this router http://www.amazon.com/SKIL-1830-120-Volt-Combo-Router/dp/B004SKY73O/ http://www.amazon.com/SKIL-1830-120-Volt-Combo-Router/dp/B004SKY73O Wes That one is not variable speed. The slower speeds are better for the aluminum. This one is the recommended router, and the one I just used to complete a lower. Worked out pretty well. http://www.amazon.com/gp/product/B000ANQHTA/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1 The skil is variable 10,000-20,000 rpm. Wes |
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Originally Posted By Wangstang:
Any one have a discount code for modulus? I have am $325 order that I would pull the pin on if I could get the price down to 275ish. Thanks Wes Send him an email with an offer, he may knock at least 10% off. All he can say is no. |
| Question: I don't have a small variable speed router, so thought I would attach a variable speed controller that will allow me to really slow down the router speed. The router Modulus recommends will only go down to 11 or 15k rpm. For those that have a mill, what would be a good rpm to run the router at for a good, controlled cut? Thanks. |
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Originally Posted By Wangstang:
The skil is variable 10,000-20,000 rpm. Wes Originally Posted By Wangstang:
Originally Posted By icrpdmeself:
Originally Posted By Wangstang:
Any reason to avoid this router http://www.amazon.com/SKIL-1830-120-Volt-Combo-Router/dp/B004SKY73O/ http://www.amazon.com/SKIL-1830-120-Volt-Combo-Router/dp/B004SKY73O Wes That one is not variable speed. The slower speeds are better for the aluminum. This one is the recommended router, and the one I just used to complete a lower. Worked out pretty well. http://www.amazon.com/gp/product/B000ANQHTA/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1 The skil is variable 10,000-20,000 rpm. Wes Oh, I skimmed the details and didn't see that. |
I swear to God I'm going to pistol whip the next guy who says, " Shenanigans."
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Originally Posted By 908ssp:
If you have a milling machine you don't need a jig of any kind. You just need a print there are many on the net available for free so don't pay for one keep looking. You don't need a CNC machine unless you are going to production. Learn to operate your milling machine and it will look better and be more accurate than any jig. I almost agree. At this point I don't use the top plates, I use the jigs to gain a square clamping surface. |
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Originally Posted By TacCar:
What are the actual dimensions for their end mill bit. I know 1/4" but how long? Looks like 4 flutes, but what bit exactly? You are correct, four flutes. Overall length about 4 inches with a cutting length about 1 inch. And it is marked USA which is always good to see. In comparison, a Hecho en China 1/4" four flute is about 2.5" overall with a cutting length a bit less than 0.75" |
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Originally Posted By XJ:
You are correct, four flutes. Overall length about 4 inches with a cutting length about 1 inch. And it is marked USA which is always good to see. In comparison, a Hecho en China 1/4" four flute is about 2.5" overall with a cutting length a bit less than 0.75" Originally Posted By XJ:
Originally Posted By TacCar:
What are the actual dimensions for their end mill bit. I know 1/4" but how long? Looks like 4 flutes, but what bit exactly? You are correct, four flutes. Overall length about 4 inches with a cutting length about 1 inch. And it is marked USA which is always good to see. In comparison, a Hecho en China 1/4" four flute is about 2.5" overall with a cutting length a bit less than 0.75" How well does that work for you? I found when I wasn't using a mill with flutes longer than the pass was deep, I ended up with chips welding to the shank of the mill. |
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Originally Posted By RyJones:
How well does that work for you? I found when I wasn't using a mill with flutes longer than the pass was deep, I ended up with chips welding to the shank of the mill. Originally Posted By RyJones:
Originally Posted By XJ:
Originally Posted By TacCar:
What are the actual dimensions for their end mill bit. I know 1/4" but how long? Looks like 4 flutes, but what bit exactly? You are correct, four flutes. Overall length about 4 inches with a cutting length about 1 inch. And it is marked USA which is always good to see. In comparison, a Hecho en China 1/4" four flute is about 2.5" overall with a cutting length a bit less than 0.75" How well does that work for you? I found when I wasn't using a mill with flutes longer than the pass was deep, I ended up with chips welding to the shank of the mill. No idea, my workspace is unheated so going to wait a while to try it out. |
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After making a few receivers with this particular jig, I have 2 tips:
1) Purchase a 1.5 inch long bolt (and matching nut) size 1/4-20. Grind or cut one side of the bolt head flat, and now use this to lock the jig front support to the pivot holes of the receiver. The instructions recommend using a front take down pin, but the bolt and nut are much more secure, and hold better tolerances. 2) Get a piece of scrap 2X4 or 2X6 lumber, 10 to 12 inches long. Use this to lay the jig flat against when you are drilling the fire control holes. The bolt head and nut that thread through the take-down holes of the receiver (that hold the jig in place) stick out a bit, so you'll need to drill a hole into the 2X4 so that it can sit flat. |
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Originally Posted By Blindeye: After making a few receivers with this particular jig, I have 2 tips: 1) Purchase a 1.5 inch long bolt (and matching nut) size 1/4-20. Grind or cut one side of the bolt head flat, and now use this to lock the jig front support to the pivot holes of the receiver. The instructions recommend using a front take down pin, but the bolt and nut are much more secure, and hold better tolerances. 2) Get a piece of scrap 2X4 or 2X6 lumber, 10 to 12 inches long. Use this to lay the jig flat against when you are drilling the fire control holes. The bolt head and nut that thread through the take-down holes of the receiver (that hold the jig in place) stick out a bit, so you'll need to drill a hole into the 2X4 so that it can sit flat. Thanks, How long did shipping take?
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I fix things that fly, so they can kill other things.
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Originally Posted By XJ:
No idea, my workspace is unheated so going to wait a while to try it out. Originally Posted By XJ:
Originally Posted By RyJones:
Originally Posted By XJ:
You are correct, four flutes. Overall length about 4 inches with a cutting length about 1 inch. And it is marked USA which is always good to see. In comparison, a Hecho en China 1/4" four flute is about 2.5" overall with a cutting length a bit less than 0.75" How well does that work for you? I found when I wasn't using a mill with flutes longer than the pass was deep, I ended up with chips welding to the shank of the mill. No idea, my workspace is unheated so going to wait a while to try it out. I suggest you buy another endmill with longer flutes and a long enough shank to get the flutes to full depth without the nose of the spindle hitting the top of the jig. Learn from my mistakes 
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umm, I got the set OP posted and the bits from the retailer. they did not send me a 5/32 bit, but a 3/16. WTF? Edit
Well I got the wrong bit in my kit. They said they will send a new one. little weird that my got a wrong. |
I fix things that fly, so they can kill other things.
| Well after looking over numerous jigs I decided to go with the modulus arms jig. The one question I have for any one who has done their 80% while using a drill press whether you have a modulus jig or not for the first few steps is, I have a TM 80% lower 7075-T6 I just wanted the recommended drill press speeds for the best results for this grade of aluminum receiver. I am not using my twelve drill press to mill it out f.y.i. Thanks for any help. |
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I got one of these jigs after reading this thread. I have done three 80% receivers thus far.
I used a mini-mill and gave up on the router. I ofund the router hard to control and controlling depth with my router wasn't easy - it kept on slipping with the 1/4 mill bit and It sould hog out mor ethan the perscribed 1/8" depth at a time. The mill worked great - no problems. One needs a long 4" bit with 1" cutting surface. I found a few on ebay cheap. I also use quality bits for any drilling, (cobalt and carbide) and this makes it easy to use on the aluminum and extended use. The only thing is the finish on mine is wearing down quickly - still works, but the holes are warn of their relativley thin anodized finish.I wish they had steel liners for the holes, but it works fine as is. I have another jig set that has a real hard or thick anodized finish and doesn't wear as easy. I plan on getting some of the spare parts from modulus. I love the jig, works great. I can whip out a lower in a few hours on a snowy day. Great way to fight cabin fever. |
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Hi Guys,
I am the new customer support/tech adviser for Modulus Arms. If you have any questions at all regarding Modulus Arms, whether they are sales or technical issues, I'm your guy. You can reach Me at [email protected] or through the chat feature on the Modulus Arms website I look forward to working with you. OP, nice job on this thread. |
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Originally Posted By maxxx93:
Hi Guys, I am the new customer support/tech adviser for Modulus Arms. If you have any questions at all regarding Modulus Arms, whether they are sales or technical issues, I'm your guy. You can reach Me at [email protected] or through the chat feature on the Modulus Arms website I look forward to working with you. OP, nice job on this thread. Great -I Love your product. Have you folks considered a template shelf that can fit closer to the receiver - so you can use a standard length mill bit (e.g. for non router milling set-ups?) |
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Originally Posted By cherenkov:
Have you folks considered a template shelf that can fit closer to the receiver - so you can use a standard length mill bit (e.g. for non router milling set-ups?) If not a router what are you milling with? If not a router why would you use this or any jig? With as nice as these jigs work with a router, its not worth trying to mill with a drill press. If you aren't using a drill press or router a mill would be about the only other method in which case you don't need a jig. Certainly not a $100+ jig. A couple of scraps of aluminum will more than suffice. I only write this after buying jigs only to realize later I didn't need them at all with a mill. $$$ would have been my h better spent on tooling which adds up FAST!! |
A firearm is like a parachute, if you need one but don't have one, you'll probably never need one again.
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Originally Posted By AFCarbon15:
If not a router what are you milling with? If not a router why would you use this or any jig? With as nice as these jigs work with a router, its not worth trying to mill with a drill press. If you aren't using a drill press or router a mill would be about the only other method in which case you don't need a jig. Certainly not a $100+ jig. A couple of scraps of aluminum will more than suffice. I only write this after buying jigs only to realize later I didn't need them at all with a mill. $$$ would have been my h better spent on tooling which adds up FAST!! Originally Posted By AFCarbon15:
Originally Posted By cherenkov:
Have you folks considered a template shelf that can fit closer to the receiver - so you can use a standard length mill bit (e.g. for non router milling set-ups?) If not a router what are you milling with? If not a router why would you use this or any jig? With as nice as these jigs work with a router, its not worth trying to mill with a drill press. If you aren't using a drill press or router a mill would be about the only other method in which case you don't need a jig. Certainly not a $100+ jig. A couple of scraps of aluminum will more than suffice. I only write this after buying jigs only to realize later I didn't need them at all with a mill. $$$ would have been my h better spent on tooling which adds up FAST!! You plan on selling those jigs? 
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Just cause people wanna eat the burger doesn't mean they wanna meet the cow.
His Karma ran over his Dogma. ~ bulldog1967
His Karma ran over his Dogma. ~ bulldog1967
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Originally Posted By AFCarbon15:
If not a router what are you milling with? If not a router why would you use this or any jig? With as nice as these jigs work with a router, its not worth trying to mill with a drill press. If you aren't using a drill press or router a mill would be about the only other method in which case you don't need a jig. Certainly not a $100+ jig. A couple of scraps of aluminum will more than suffice. I only write this after buying jigs only to realize later I didn't need them at all with a mill. $$$ would have been my h better spent on tooling which adds up FAST!! Originally Posted By AFCarbon15:
Originally Posted By cherenkov:
Have you folks considered a template shelf that can fit closer to the receiver - so you can use a standard length mill bit (e.g. for non router milling set-ups?) If not a router what are you milling with? If not a router why would you use this or any jig? With as nice as these jigs work with a router, its not worth trying to mill with a drill press. If you aren't using a drill press or router a mill would be about the only other method in which case you don't need a jig. Certainly not a $100+ jig. A couple of scraps of aluminum will more than suffice. I only write this after buying jigs only to realize later I didn't need them at all with a mill. $$$ would have been my h better spent on tooling which adds up FAST!! I use a mini-milling machine - All hand controlled, It works and I like it. I tried it with the router, and it worked fine, I just prefer to putter on the mill. I sit and have a coffee and putter - makes for a good project on a cold day. The jig makes it a no-brainer for staying in the lines and drilling the fire control and safety holes. I like the Modulus Jig because it accomodates most any receiver (forged or billett) and centers on the buffer tube hole and front axis pin. I am not a machinist by any means, but enjoy making my own - even if it costs a little more. |
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Originally Posted By cherenkov:
I use a mini-milling machine - All hand controlled, It works and I like it. I tried it with the router, and it worked fine, I just prefer to putter on the mill. I sit and have a coffee and putter - makes for a good project on a cold day. The jig makes it a no-brainer for staying in the lines and drilling the fire control and safety holes. I like the Modulus Jig because it accomodates most any receiver (forged or billett) and centers on the buffer tube hole and front axis pin. I am not a machinist by any means, but enjoy making my own - even if it costs a little more. Originally Posted By cherenkov:
Originally Posted By AFCarbon15:
Originally Posted By cherenkov:
Have you folks considered a template shelf that can fit closer to the receiver - so you can use a standard length mill bit (e.g. for non router milling set-ups?) If not a router what are you milling with? If not a router why would you use this or any jig? With as nice as these jigs work with a router, its not worth trying to mill with a drill press. If you aren't using a drill press or router a mill would be about the only other method in which case you don't need a jig. Certainly not a $100+ jig. A couple of scraps of aluminum will more than suffice. I only write this after buying jigs only to realize later I didn't need them at all with a mill. $$$ would have been my h better spent on tooling which adds up FAST!! I use a mini-milling machine - All hand controlled, It works and I like it. I tried it with the router, and it worked fine, I just prefer to putter on the mill. I sit and have a coffee and putter - makes for a good project on a cold day. The jig makes it a no-brainer for staying in the lines and drilling the fire control and safety holes. I like the Modulus Jig because it accomodates most any receiver (forged or billett) and centers on the buffer tube hole and front axis pin. I am not a machinist by any means, but enjoy making my own - even if it costs a little more. Sounds just like me!!! I have a LMS 3900, I started with a jig, because I didn't know and honestly it made me feel more comfortable, somehow more fool proof. But with some cheap DROs and a lot of confidence gained from a little experience and a TON of research, I only use the jigs to hold lowers in the vise. I have made blocks to do the same, but because I have them, I still use the jig sometimes. Sorry to hijack the thread but these little convos have helped me more than I can explain. |
A firearm is like a parachute, if you need one but don't have one, you'll probably never need one again.
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Thanks Paul for your review of this jig I finally pulled the trigger and went with this one after a lot of research.
I think it turned out pretty good for the first time doing a 80% lower. FYI I did mine with a drill press and a router. Thanks again. |
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Originally Posted By B7R:
Thanks Paul for your review of this jig I finally pulled the trigger and went with this one after a lot of research. I think it turned out pretty good for the first time doing a 80% lower. FYI I did mine with a drill press and a router. Here are a couple of pics. Thanks again. http://i62.tinypic.com/2qbx05d.jpg http://i60.tinypic.com/40yee.jpg Who did the engraving, and what's up with the bead blasting? Looks goo tho, congrats ! 
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A firearm is like a parachute, if you need one but don't have one, you'll probably never need one again.
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Originally Posted By AFCarbon15:
Who did the engraving, and what's up with the bead blasting? Looks goo tho, congrats ! Originally Posted By AFCarbon15:
Originally Posted By B7R:
Thanks Paul for your review of this jig I finally pulled the trigger and went with this one after a lot of research. I think it turned out pretty good for the first time doing a 80% lower. FYI I did mine with a drill press and a router. Here are a couple of pics. Thanks again. http://i62.tinypic.com/2qbx05d.jpg http://i60.tinypic.com/40yee.jpg Who did the engraving, and what's up with the bead blasting? Looks goo tho, congrats ! Fellow arfcomer Braceman did all the A1 re profiling and engraving. I think after he milled the rear to the A1 profile he did the bead blasting. I just did the selector, trigger, hammer pin holes, and milled out the front and rear fire control pocket. It is off being anodized right now. |
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Great write up, OP!
I didn't see this thread before I purchased a different jig, and if I didn't have access to a mill I think I would have preferred this one. The MA instruction write up was very detailed. Someone else posted it earlier, but here's the link again. Jig Instructions I found it odd that MA's instructions started with the trigger slot. I could see drilling the trigger slot holes first as they go all the way through the lower, but why not wait to machine the slot until after the fire control pocket is milled out? It seems to me that you'd be "wasting" time milling material in the FCP area that is just going to be removed later. Anyone (maxxx93 ?) have insight on why this approach would be better/worse than milling the FCP pocket before finishing the trigger slot? ETA: I see that OP mentioned having the extra FCP material support the tool when milling the trigger slot... |
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anyone else having trouble with the bosch router they recommend? the mill bit keeps "walking" out of the collet, and milling more than its supposed to. if you tighten the collet too much, it breaks the collet. on my 3rd collet, and the bit still slides out while milling. wish the mill bit had a knurled shank, so it would stay in the collet better.
other than that, this jig rocks. 
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Originally Posted By badfishy:
anyone else having trouble with the bosch router they recommend? the mill bit keeps "walking" out of the collet, and milling more than its supposed to. if you tighten the collet too much, it breaks the collet. on my 3rd collet, and the bit still slides out while milling. wish the mill bit had a knurled shank, so it would stay in the collet better. other than that, this jig rocks. I never had a issue and I used the bosch just made sure the collet was nice and tight. And always double checked my depths with a caliper nothing special. Sorry to hear you have had issues. |
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Originally Posted By Paul:
Modulus Arms is new to the 80% lower jig manufacturers. Their Modulus Arms Universal AR-15 80% Lower Receiver Jig is unique in many ways. This is my fourth jig (yeah I know) and I've found that not every lower fits every jig ... until now. Because of the way Modulus Arms jig is designed it appears that they've solved that problem. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusKit_zps1d0f79b4.jpg Every 80% AR-15 lower that will work with a standard upper and receiver extension has two points where the upper has to index: the front take down tab and the buffer tube/receiver extension tapped hole. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusJigandLower_zps5e9531b9.jpg There is a round plug that treads into the buffer tube which allows the jig to index off the rear of the receiver. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusRearMount_zpsb46aaa89.jpg And another jig part that connects into the front take down notch where is it held in place either with the take down pin or with a 1/4" aluminum dowel like I used. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusFrontMount_zps91e62501.jpg Together these two parts index and hold the cutting jig in place for the three areas that need to be cut - the rear shelf cut to 0.620", the trigger hole cut all the way through, and the main pocket for the trigger cut to 1.249" deep. In the photo below the jig is oriented to cut the first two of those pockets - the rear shelf and the trigger holes. Not shown for clarity are the side supports. To cut the main pocket the top of the jig is unscrewed, rotated 180 degrees and re-attached. A very simple and well thought out system. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusJigTopAssembled_zpsaf1a672b.jpg I had a couple of 80% lowers waiting to be finished so I fired up the mini-mill to have at one. The Modulus Arms jig is designed to be completed with a drill/drill press and either using a handheld router or a mill. The top surface is designed to lay a small router up on top and use a 1/4" end mill to complete. I recommend using a variable speed plunge type router if you're going to use ... this route as you'll want to cut with a lower speed on aluminum than crazy wicked speeds of a fixed router and the plunge adjustment will make using the include depth gauge easier. Milling out the pockets is a lot of work on the tool which can be done with a cheaper/faster drill bit. Modulus sells a small kit with the required 1/4" carbide end mill, 3/8" drill bit and drill stop, a 19/64" bit for the trigger hole, and a 5/32" for cutting the trigger and disconnector side holes. Available here. I connected the jig up and drilled out parts of the pockets using the include depth guide. The 3/8" drill stop is used to limit the plunge depth of the drill press. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusDepthJig_zps693b3221.jpg 3/8" holes are cut in the rear for the shelf that the upper drops down against for the take down pin. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusRearShelfDepth_zpsa090f221.jpg The 19/64" bit cuts the trigger hole all the way down through the bottom of the lower. The milling of the trigger hole is then done. This is different that many other jigs in that the bulk of the pocket material is still there supporting the end mill cutting tool. In some of my lowers when completing the trigger hold with the pocket already cleared the cutting tool wants to cut "outside the lines" as you're using a small 1/4" mill at close to 2" of length. A side view http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusSideView_zps80e5fe12.jpg The result is pretty nice. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusTriggerExit_zps4cdbf01f.jpg You then mill out the rear shelf. The jig is held up above the surface of the lower which does two important things. First and most importantly it protects the jig from the cutting action of the end mill. Having the tool below the jig's side makes it impossible to nick the jig. Secondly the space allows the swarf a place to gather and pour out so that the work is easier and the upper surface of the lower is protected. In the photo below I've removed the cutting jig to rotate it around for the main pocket work. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusRearMilling_zpsd026ece8.jpg And results. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusTriggerandRearShelfDrilled_zps187ae928.jpg The included drill bit guide mounts under the jig template to guide the 3/8" and 19/64th holes. Starting and stopping the drill press while inside the holes protects the guide from getting cut up too badly. The jig includes all the needed cap screws. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusDrillOutAdapter_zpsba95cad7.jpg Making lots of chips with the drill saves the wear and tear on the end mill tool. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusChipMaking_zps1699dd1f.jpg Milling is done with a 1/4" end mill. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusCenterMilling_zps6279b361.jpg After a bit of milling out pops a completed fire control pocket. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusPocketMilledTopView_zps87b316e7.jpg http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusPocketMilled45_zpseb7ca735.jpg Another unique feature of the jig is that the safety/selector, trigger pin, and disconnector pin holes on the jigs side are provided twice - there's a set on top and rotating the left to right side and flipping them over the bottom pair can be used as well. That's a pretty neat feature. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusSidePins_zpsf4b619d8.jpg The results look very nice. http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusSideHoles_zpsf0a1c949.jpg http://i104.photobucket.com/albums/m168/AR-15_Paul/Rifles/Modulus%20Arms%20Jig/ModulusCompleted_zps748823e1.jpg The Modulus Arms web site indicates that they're working on a .308 upper. 
This jig solves the issue of having to match your jig to your 80% lower. It can be done simple tools like a drill press and a handheld variable speed plunge router or a mini mill. The fit and finish of the jig is top notch and shows that the designer has thought out the 80% completion process completely. I can most highly recommend this jig. Great review, thanks Paul... The only thing that would make the jig better is having hardened steel bushings on both sides for the safety, hammer, and trigger holes and for the price it should IMHO...then, It would be considered tops in its class/category. Then it can be used several times over w/o fear of loosing spec. for your critical hole locations etc. The only other practical way to help avoid dimensional distortion/wear on the jig for your critical holes is by using a center/edge finder for exact drill location or if your lucky enough to have a accurate mill w/ a 3-Axis DRO and use both for dead nuts accuracy... Just my two pennies... |
| I purchased the jig and 80% lower and upper at one time. After doing all the routing, I noticed the hole that retains the spring located under the pistol grip was partially exposed from the milling process. I 'chatted' online with a Modulus tech rep, and he suggested that I must have 'colored outside the line.' I lost the connection, so our discussion did not go any further. I guess my question would be, if the Modulus jig centers the lower to the jig, how can one mill outside the line? I shouldn't be able to put the blame on the lower, as it is sold by Modulas as well. Has anyone else had this problem? |
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Originally Posted By Donj441:
I purchased the jig and 80% lower and upper at one time. After doing all the routing, I noticed the hole that retains the spring located under the pistol grip was partially exposed from the milling process. I 'chatted' online with a Modulus tech rep, and he suggested that I must have 'colored outside the line.' I lost the connection, so our discussion did not go any further. I guess my question would be, if the Modulus jig centers the lower to the jig, how can one mill outside the line? I shouldn't be able to put the blame on the lower, as it is sold by Modulas as well. Has anyone else had this problem? Why didn't you call back? Which spring are you talking about exactly? The safety selector spring is supposed to protrude from the lower and partially extend into you pistol grip. Wes |
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Originally Posted By Wangstang:
Why didn't you call back? Which spring are you talking about exactly? The safety selector spring is supposed to protrude from the lower and partially extend into you pistol grip. Wes Originally Posted By Wangstang:
Originally Posted By Donj441:
I purchased the jig and 80% lower and upper at one time. After doing all the routing, I noticed the hole that retains the spring located under the pistol grip was partially exposed from the milling process. I 'chatted' online with a Modulus tech rep, and he suggested that I must have 'colored outside the line.' I lost the connection, so our discussion did not go any further. I guess my question would be, if the Modulus jig centers the lower to the jig, how can one mill outside the line? I shouldn't be able to put the blame on the lower, as it is sold by Modulas as well. Has anyone else had this problem? Why didn't you call back? Which spring are you talking about exactly? The safety selector spring is supposed to protrude from the lower and partially extend into you pistol grip. Wes he is talking about the rear safety selector spring. My second lower out of the jig slightly broke through also. I follow the directions to a tee. I figured the cheap lower I bought might have been out of spec though. 
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I swear to God I'm going to pistol whip the next guy who says, " Shenanigans."
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Originally Posted By icrpdmeself: he is talking about the rear safety selector spring. My second lower out of the jig slightly broke through also. I follow the directions to a tee.
I figured the cheap lower I bought might have been out of spec though. Was there more than 50% of the channel left? Does it still hold the spring and detent? |
Managing Member of Mischief - Thanks to HammerHammer for the Team Membership.
| It still holds it, but I wouldn't want to rely on it in a do or die situation. I got it mostly for target practice and for home defense. I'm thinking about getting another 80%'er, but not sure which one would be better under the milling process. The downside to the one I have is that I had it engraved before noticing the issue...the engraving cost me more than the lower. |
Modulus Arms 80% Lower Jig Review (photo heavy) (Page 2 of 4)
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