Drill Press and Hole Closest to Magwell Question

[spyde12]

Equipment
Variable speed Wei drill press
Drill press vise
Dewalt variable speed Laminate Router (edited)
Tap cutting fluid
Modulus Arms Universal AR15 jig
Modulus Arms fabrication toolkit
Tactical Machining AR15 80% lower
New Frontier AR15 80% lower

Intro
I'm trying to figure out whether the issue I ran into with 2 lowers was due to my technique (user error), drill press, or drill bit. When drilling the hole closest to the magwell, it appears that it matches the drill hole template. However, when I mill the pocket, I notice that the drilled hole was a little off. So the border of the pocket closest to the magwell isn't a straight edge. It's slightly rounded. I also tried with a different lower and I ran into the same issue as well.
The only work around I came up with was to use a smaller drill bit (the one used to drill the trigger) for the first hole. Then do the rest with the recommended bit. They're all functional and no one will notice since it's hidden once the upper installed.

Question(s)
Is the rounded edge due to my equipment?
Is it due to my technique?
Is it due to the lower?
Anyone have any helpful tips?

Thank you in advance

Reference




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[kcstott]

You assume your jig is correct. And that may not be the case.

[spyde12]

You assume your jig is correct. And that may not be the case.

Yea, that's what I meant by the first question. If it's my equipment (i.e. the jig), then I can live with it and make adjustments. I was hoping it was my technique (i.e. rpm and/or down force of the drill press) since that's easier to correct.

BTW, I enjoy reading your contributions to the gunsmith thread. I've learned a lot just from reading old posts/responses and limit my questions since it's probably been asked and answered numerous times already.

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[kcstott]

Heres a tip lay both plates on top of each other and line them up to the locating pin or surfaces they use. then see if the drill plate is correct to the mill plate.

I never like Modulus arms, they came here pushing their product, bad mouthing other companies. not to mention the shill postings here and over on other boards, That ain't how you start off as a FNG on the block.

Come in modest, tell us what you have why you feel it's better with out bad mouthing the competition and you will then have a leg to stand on. I still say these guy were out to make a fast buck and nothing more.


Anyway what you need to do is confirm the jig is correct, if it is then you can look at your equipment

[lostwake]

I have seen this before. Did you drill the hole after you milled the pocket?

[kcstott]

I don't think he means FCG holes.

[GMG]

Maybe I'm reading it wrong, but wouldn't the hole closest to the mag well be the hammer pin hole?

[bohoki]

i think that is the hammer hole

compare its location to a known good lower if you mean the internal milling it looks uneven toward the front and can cause issues with the hammer rotating on the pin you may need to reattach the endmill and adjust that area

[spyde12]

Heres a tip lay both plates on top of each other and line them up to the locating pin or surfaces they use. then see if the drill plate is correct to the mill plate.

I never like Modulus arms, they came here pushing their product, bad mouthing other companies. not to mention the shill postings here and over on other boards, That ain't how you start off as a FNG on the block.

Come in modest, tell us what you have why you feel it's better with out bad mouthing the competition and you will then have a leg to stand on. I still say these guy were out to make a fast buck and nothing more.


Anyway what you need to do is confirm the jig is correct, if it is then you can look at your equipment

Thank you for the advice. I just bought an 80 Percent Easy jig. I can't wait to compare.

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[spyde12]

I have seen this before. Did you drill the hole after you milled the pocket?

Yes, I drilled the hole after milling out the trigger. I followed directions to the T for both instances and got the same results.

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[sonofeugene]

There's a reason mills exist. It's because drills, no matter how good, do a lousy job milling.

It continues to boggle my mind that people use drills as mills and wonder why the results are so crappy.

[lostwake]

Yes, I drilled the hole after milling out the trigger. I followed directions to the T for both instances and got the same results.

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I had that happen. It seemed like the drill bit would walk. I think the drillpress does not hold the bit steady enough. The lower was completely functionable, It just looked like the hammer was cocked to one side.

[Devilmonkey89]

There's a reason mills exist. It's because drills, no matter how good, do a lousy job milling.

It continues to boggle my mind that people use drills as mills and wonder why the results are so crappy.

Not all of us have access to a mill. Since its illegal to rent one, we use what we legally can to contiune our hobby. I used the router and endmill method. OP my MA jig has the same issue. I believe mine wore out from the steel endmill rubbing against the aluminum top plate. Maybe yours has that same issue?

[spyde12]

I had that happen. It seemed like the drill bit would walk. I think the drillpress does not hold the bit steady enough. The lower was completely functionable, It just looked like the hammer was cocked to one side.

If that's the case (drill bit walking), would the root cause be due to:
1. The speed of the drill
2. The initial downward force when contact is first made with the lower
3. Cheap drill bit

I forgot to mention that the 3rd time I tried using the jig, I used the supplied screw that is inserted into the rear take down hole. That appeared to have stabilized the lower from moving. However, I didn't drill the hole closest to the magwell like I did with the other 2 to find out.

I'm thinking about using a flashlight and shine it down the template holes facing the lower. Then I'd trace the circle with a pencil where the hole would appear. Afterwards, I'd do the same with the mill guide plate and see if it's off. That'll be the cheapest way to determine if it's the jig or not without risking a good lower in the process.

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[boopiejones]

which hole are you talking about? one of the large holes that you drill with the 3/8 bit before using an endmill to finish out the pocket? there is another post from today with what sounds like the same issue. but he was using an 80% arms easy jig:

http://www.calguns.net/calgunforum/showthread.php?t=1061950

assuming that is the hole you are talking about, i wouldn't worry about it. i've done much worse with some of my lowers and they still work just fine.