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Thread: EPArmory VS Polymer80

  1. #1
    Gunco Member BKBrno's Avatar
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    Default EPArmory VS Polymer80

    Bought one of each. EPArmory standard. Polymer80 blem.

    EPArmory didn't need any jigs so I started with that one. Worked out OK. Some voids where there shouldn't be in the pocket. No way in hell you can drill the various hole as well as they need to be. They need a jig for this, their little dimples don't cut it. Safety selector hole is way off due to drill walking. I need to fill with epoxy and try again. Trigger pins were off enough that they had to be wallowed out a little to get the pins in. I should have cleaned the dingle berries better. Something got in the pivot plunger and it is hopelessly stuck in its little hole. All up, I give it a solid C. Not the best but should work. I used a drill press to hog out most of the material before going to the dremel. The plastic is pretty tough. Dulled 2 Dremel 115 cutters cleaning out the pocket. Also used a sanding drum and drywall cutter bit smoothing things up. Drywall cutter worked nice for getting little bits in corners.

    Polymer80. This was a blem. I noticed some scuff marks, don't see anything else that stands out. I need to get my mini mill set up before starting this one. I learned from the EP lower that you need a rigid clamping method. There is a lot of force on the cutters and my drill press isn't solid enough to hold things down. No build report yet. This lower seems like they make the most adjustments for being polymer vs. Al. More later.

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    GuncoHolic Sprat's Avatar
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    EP 80 % with a drillpress
    if you used a smaller bit and slowly drilled into the concave area of the dimple, once drilled then go to the proper size bit will acheive the proper location for trigger pin, I an others did not have the problem you experienced, ?
    Sprat and sprat1 are one and the same.

  3. #3
    Gunco Member BKBrno's Avatar
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    I have the skills and equipment to a much more precision job. I opted to do it as they described with a little bubba sprinkled on top to see where the problems would be.

    Here are some high points:

    The plastic is a lot more difficult to machine than one might think. It grabs cutters with a lot of force and twists out of holding device easily. No problem using small, high speed dremel bits. No way you can use an end mill in a drill press. I tried. A jig that holds the receiver would be a big bonus. The EP lower seems to be the closest, in dimensions to a standard lower so any jig made for machining an aluminum receiver might work. Don't know.

    I used new, sharp drill bits. They grabbed and pulled through the plastic with a lot of force. Drill bits ground for cutting plastic would be the correct tool for this. I know the are made or can be ground for this. Don't have any.

    You must deburr every hole and clean out every last bit of fluff. One small sliver has hopelessly jammed the pivot pin detent. I plan to go over the next one with a magnifying glass to make sure there are no surprises.

    I have a workable receiver that will be fine on my .22 upper.

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    GuncoHolic Sprat's Avatar
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    quote
    The plastic is a lot more difficult to machine than one might think. It grabs cutters with a lot of force and twists out of holding device easily. No problem using small, high speed dremel bits. No way you can use an end mill in a drill press. I tried. A jig that holds the receiver would be a big bonus. The EP lower seems to be the closest, in dimensions to a standard lower so any jig made for machining an aluminum receiver might work. Don't know.

    if you read the entire Polymer lower thread you would know that ep 80% don't fit in standard jigs used for aluminum

    quote
    I used new, sharp drill bits. They grabbed and pulled through the plastic with a lot of force. Drill bits ground for cutting plastic would be the correct tool for this. I know the are made or can be ground for this. Don't have any.

    I used standard drill bits from home depot nothing

    yes you should go throughevery hole with a drill bit by hand to debur and open up some of the predrilled hole

    end mill seem to be over kill for these, drill press, hand drill and dremel is all you need

    no questioning your specific skill set

    please read the existing thread Polymer 80% lowers
    Sprat and sprat1 are one and the same.

  5. #5
    3/6 Infantry mtdew's Avatar
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    Quote Originally Posted by Sprat View Post
    EP 80 % with a drillpress
    if you used a smaller bit and slowly drilled into the concave area of the dimple, once drilled then go to the proper size bit will acheive the proper location for trigger pin, I an others did not have the problem you experienced, ?
    ^ I agree with working up drill bit size. I also used a 3/8 end mill in my drill press with a cross slide vise for the fcg pocket. It worked very well. http://www.gunco.net/forums/attachme...1&d=1383746676
    "NA BEAN DON CHAT GUN LAMHAINN"
    Clan MacPherson
    "CREAG DHUBH"!

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