Hey guys!
I just milled my HS Precision stock in order to be able to screw in an ARCA rail for tripod use, and realized I wouldn't be able to clamp my trusty Harris bipod anymore without an adapter (by the way, received great service from Precision Zone for that APW ARCA rail, looks pretty sweet and is priced right!). I know Area 419 makes a great adapter clamp, but couldn't justify the steep price, hell it's as expensive as the bipod itself.
Just wanted to share with y'all the clamp I designed, thought that it could maybe help some of you guys save the design time if you have access to the machines and tooling necessary to make it yourself. Feel free to send me a PM if you want the CAD files or drawings, or to modify the design to your liking. Designed it on SW 2020-2021, but can save the files in any format you might want.
I wanted to manufacture every part for the fun of it, but using off the shelf components for the bolt, washer and dowel pins would make it possible for you to make without the use of a lathe if you only have access to a milling machine. Only basic tooling is required, except for the 45 deg dovetail (standard is 60 deg), which hopefully you have lying around. The only things I had to buy are the springs, which are kinda specific (McMaster part #9434K36). I modified (shortened) the swivel stud that was on my rifle for this, no need to purchase one! Just slowly shortened it until the shoulder hit at the right spot for alignment. BIG TIP here; use some red Loctite to hold the swivel stud in place, it's not like you'll ever have to remove it. Blue will not hold (believe me, I tried), and you'll constantly have it rotate on ya when folding or unfolding the bipod legs.
Here are the parts:
1. Main body
I decided to make most of the clamp with 6061-T6 aluminum due to availability, price and weight. Just so you don't make the same mistake I did at first, here's a tip; leave yourself .010" of material in depth (go to .170" instead of the full .180" depth) when you face mill the bottom of the ARCA surface. This will allow you to have the bottom surface flat all across as you machine the 45 deg dovetail (just start by face milling to depth and make continue in the wall to make the dovetail). On the first one I made, I tried to zero off the bottom surface which was already milled to depth and it left small step. Granted it's only a couple thou, but it prevents the surface from clamping flat. I suggest making a few test holes in scrap material to make sure to control the fits between the part and the dowel pins. The small step in the dowel pin holes is used as a stop for the spring. Food for thought; a threaded insert or heli-coil could be used here in order to strengthen the threads. The force going through isn't excessive, but I have always hated threading in aluminum.
Here's the drawing and a few pics of the actual part: https://drive.google.com/drive/folders/1ezdCP9Wh4tMoN58RR3yhV_CLOp4s5PFr?usp=sharing
2. Clamping body
6061-T6 was used for this part. Again, I suggest making a few test holes in a scrap part to make sure to control the fits between the part and the dowel pins/bolt. These tight clearance fits are the only thing preventing the clamping body to cam under load, which would result in clamping on a line instead of engaging the whole surface. I used epoxy to fix the dowel pins to this part (I poured the epoxy in the hole and clamped everything together to make sure that the pins were glued straight. Wanted to make a press fit at first, but there just isn't enough surface to grip the pin. Food for thought; to get a good press fit, the dowel pin hole could maybe be thru all and the excess material milled from the back side? Again, the small step in the dowel pin holes is used as a stop for the spring.
Here's the drawing and a few pics of the actual part: https://drive.google.com/drive/folders/1ZKTiinUbCg_nvrh1N34ZRBm58yKMaJay?usp=sharing
3. Bolt
I used some sort of unknown rust proof steel alloy to make the bolt in order to avoid galling as much as possible. The bolt was custom made mostly to provide a third surface of contact that prevents the clamping body from camming under load. An off the shelf bolt could be used here, but dang, I love the look of that bolt handle
Thread choice is up to you, but I suggest keeping them fine for the peace of mind that it provides. Shock and vibration are part of the game here, and it could potentially make a coarse threaded bolt come loose. Small tip; make sure the tool radius is removed on the locating surface in order to have a flat face in contact with the washer... or just make the clearance hole in the washer bigger to accommodate.
Here's the drawing and a few pics of the actual part: https://drive.google.com/drive/folders/1AJ0JPx0v89lOtFQhdE8lHPRERzMBK4sB?usp=sharing
4. Dowel/Alignment Pins
I used brass here for the looks, but man machining these was hard. Brass is so soft that any sort of tool pressure at that diameter will induce crazy runout. I you do decide to use this material, keep your depth of cuts tiny. If I had to do it again, I'd go with aluminum at the minimum. Just make sure that the material you use won't rust.. the fits are kinda tight. If you do not want to go through the trouble, just buy some damn 3/16" dowel pins!
Here's the drawing and a few pics of the actual part: https://drive.google.com/drive/folders/1DR5XmFm8YE0hErpVTmx0rrkwa0XAKRwJ?usp=sharing
5. Washer
Did I already say how much I like brass? Lol. Was a custom washer necessary? Nah. Does it make the clamp look good? Hell yeah! Just make sure you use one, or the steel bolt will eat the aluminum as you open and close the clamp.
Here's the drawing and a few pics of the actual part: https://drive.google.com/drive/folders/13suCq2FdOlS17mKwZwASF6YAdj3m3XA9?usp=sharing
If you want to see pics of the completed and installed clamp, click on this link: https://drive.google.com/drive/folders/1J-6hcL_FNR8_jTyv7ytJeMi42J2xSlVZ?usp=sharing
Well, there it is guys! As I said, if you want the CAD or SW drawings, just hit me up with a PM. Feel free to use, share or modify this design as you wish. If you do change it, don't forget to post your ideas here so we can improve the product together! I'll be grateful if this post can help just one guy or gal make their own clamp!
Good machining and good shooting!
I just milled my HS Precision stock in order to be able to screw in an ARCA rail for tripod use, and realized I wouldn't be able to clamp my trusty Harris bipod anymore without an adapter (by the way, received great service from Precision Zone for that APW ARCA rail, looks pretty sweet and is priced right!). I know Area 419 makes a great adapter clamp, but couldn't justify the steep price, hell it's as expensive as the bipod itself.
Just wanted to share with y'all the clamp I designed, thought that it could maybe help some of you guys save the design time if you have access to the machines and tooling necessary to make it yourself. Feel free to send me a PM if you want the CAD files or drawings, or to modify the design to your liking. Designed it on SW 2020-2021, but can save the files in any format you might want.
I wanted to manufacture every part for the fun of it, but using off the shelf components for the bolt, washer and dowel pins would make it possible for you to make without the use of a lathe if you only have access to a milling machine. Only basic tooling is required, except for the 45 deg dovetail (standard is 60 deg), which hopefully you have lying around. The only things I had to buy are the springs, which are kinda specific (McMaster part #9434K36). I modified (shortened) the swivel stud that was on my rifle for this, no need to purchase one! Just slowly shortened it until the shoulder hit at the right spot for alignment. BIG TIP here; use some red Loctite to hold the swivel stud in place, it's not like you'll ever have to remove it. Blue will not hold (believe me, I tried), and you'll constantly have it rotate on ya when folding or unfolding the bipod legs.
Here are the parts:
1. Main body
I decided to make most of the clamp with 6061-T6 aluminum due to availability, price and weight. Just so you don't make the same mistake I did at first, here's a tip; leave yourself .010" of material in depth (go to .170" instead of the full .180" depth) when you face mill the bottom of the ARCA surface. This will allow you to have the bottom surface flat all across as you machine the 45 deg dovetail (just start by face milling to depth and make continue in the wall to make the dovetail). On the first one I made, I tried to zero off the bottom surface which was already milled to depth and it left small step. Granted it's only a couple thou, but it prevents the surface from clamping flat. I suggest making a few test holes in scrap material to make sure to control the fits between the part and the dowel pins. The small step in the dowel pin holes is used as a stop for the spring. Food for thought; a threaded insert or heli-coil could be used here in order to strengthen the threads. The force going through isn't excessive, but I have always hated threading in aluminum.
Here's the drawing and a few pics of the actual part: https://drive.google.com/drive/folders/1ezdCP9Wh4tMoN58RR3yhV_CLOp4s5PFr?usp=sharing
2. Clamping body
6061-T6 was used for this part. Again, I suggest making a few test holes in a scrap part to make sure to control the fits between the part and the dowel pins/bolt. These tight clearance fits are the only thing preventing the clamping body to cam under load, which would result in clamping on a line instead of engaging the whole surface. I used epoxy to fix the dowel pins to this part (I poured the epoxy in the hole and clamped everything together to make sure that the pins were glued straight. Wanted to make a press fit at first, but there just isn't enough surface to grip the pin. Food for thought; to get a good press fit, the dowel pin hole could maybe be thru all and the excess material milled from the back side? Again, the small step in the dowel pin holes is used as a stop for the spring.
Here's the drawing and a few pics of the actual part: https://drive.google.com/drive/folders/1ZKTiinUbCg_nvrh1N34ZRBm58yKMaJay?usp=sharing
3. Bolt
I used some sort of unknown rust proof steel alloy to make the bolt in order to avoid galling as much as possible. The bolt was custom made mostly to provide a third surface of contact that prevents the clamping body from camming under load. An off the shelf bolt could be used here, but dang, I love the look of that bolt handle
Thread choice is up to you, but I suggest keeping them fine for the peace of mind that it provides. Shock and vibration are part of the game here, and it could potentially make a coarse threaded bolt come loose. Small tip; make sure the tool radius is removed on the locating surface in order to have a flat face in contact with the washer... or just make the clearance hole in the washer bigger to accommodate. Here's the drawing and a few pics of the actual part: https://drive.google.com/drive/folders/1AJ0JPx0v89lOtFQhdE8lHPRERzMBK4sB?usp=sharing
4. Dowel/Alignment Pins
I used brass here for the looks, but man machining these was hard. Brass is so soft that any sort of tool pressure at that diameter will induce crazy runout. I you do decide to use this material, keep your depth of cuts tiny. If I had to do it again, I'd go with aluminum at the minimum. Just make sure that the material you use won't rust.. the fits are kinda tight. If you do not want to go through the trouble, just buy some damn 3/16" dowel pins!
Here's the drawing and a few pics of the actual part: https://drive.google.com/drive/folders/1DR5XmFm8YE0hErpVTmx0rrkwa0XAKRwJ?usp=sharing
5. Washer
Did I already say how much I like brass? Lol. Was a custom washer necessary? Nah. Does it make the clamp look good? Hell yeah! Just make sure you use one, or the steel bolt will eat the aluminum as you open and close the clamp.
Here's the drawing and a few pics of the actual part: https://drive.google.com/drive/folders/13suCq2FdOlS17mKwZwASF6YAdj3m3XA9?usp=sharing
If you want to see pics of the completed and installed clamp, click on this link: https://drive.google.com/drive/folders/1J-6hcL_FNR8_jTyv7ytJeMi42J2xSlVZ?usp=sharing
Well, there it is guys! As I said, if you want the CAD or SW drawings, just hit me up with a PM. Feel free to use, share or modify this design as you wish. If you do change it, don't forget to post your ideas here so we can improve the product together! I'll be grateful if this post can help just one guy or gal make their own clamp!
Good machining and good shooting!
