DIY Jammer Arm Instructions

Written by: Kyle Divine

Video Instructions

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Introduction

Hey everybody, this week we are making jammer arms. These babies have been requested more times than anything else on my to-do list. 

My version is a little different from what is currently available to purchase. Instead of moving in a single plane of motion, these swivel and move in all directions.

The time to build is about 60 to 90 minutes, and it likely costs between $120-$150. The overall difficulty is medium.

Recommended Tools

Tool	Link #1	Link #2
Dewalt sliding mitre saw	Amazon	Home Depot
Dewalt cordless drill	Amazon	Home Depot
Bosch cordless drill set	Amazon
Drill press	Amazon	Home Depot
Dewalt random orbit sander	Amazon	Home Depot
1-inch Forstner bit	Amazon	Home Depot
5/8 inch Forstner bit	Amazon	Home Depot
1/4 inch drill bit	Amazon	Home Depot
Socket adapter for drill	Amazon
Wood clamps	Amazon	Home Depot
Rafter square	Amazon	Home Depot
Rubber mallet	Amazon	Home Depot

Recommended Materials

Materials	Link #1	Link #2
1 – 8ft 4×4 – Home Depot link	Home Depot
1 – 1 x 6 board	Home Depot
8 – 6” long 1” steel pipe	Amazon	Home Depot
2 – 3” long 1” steel pipe	Amazon	Home Depot
2 – 45 degree 1” pipe fitting	Amazon	Home Depot
4 – 90 degree 1” fitting	Amazon	Home Depot
6 – 1” floor flange	Amazon	Home Depot
2 – 1” pipe cap	Amazon	Home Depot
10-inch pneumatic swivel caster	Amazon	Home Depot
16 – #12 screws 2 ½” long	Amazon
8 – #14 screws 1 ½” long	Amazon
1/4” bolts, 2 inches long with lock nuts and washers	Amazon
6 inch long 1” bolts	Menards
1” hex nut	Menards
Early American wood stain	Home Depot
Black spray paint	Amazon	Home Depot

Instructions

Step 1: I start by cutting my 2×6 into two 10 inch pieces, then grab the 4×4 and cut it into two 38 inch pieces.

Step 2: My power rack is 3×3 with 1-inch holes spaced 2 inches apart. To make it easy on myself, I hold the 2×6 up to the rack and mark where the holes will go. I only mark the top and bottom holes. 

Step 3: To make sure the holes are identical on each 2×6, I clamp them both to my drill press and drill through with my 1-inch Forstner bit. 

Step 4: The bit is only long enough to go halfway through the bottom piece, so I unclamp them and drill the rest of the way through the bottom part.

Step 5: On the 4x4s, I measure 1 3/4 inch from the end and mark the center.

Step 6: Then drill through with a 5/8 inch Forstner bit. The size of this hole depends on the size of the bolt on your caster. You want it to be a snug fit. 

Step 7: The pipes screw together. You’ll want to make sure they’re nice and tight.

Step 8: When you’re done screwing everything together, they should look like this. 

Step 9: The flange goes on the opposite side from where I drilled the hole. I attach it pretty close to the bottom but not quite flush with the bottom. Predrill before the screws go in, so the wood doesn’t split. 

Step 10: Then, I use super thick 2 1/2 inch screws to secure it. 

Step 11: Screw the second flange and tap it into place with a rubber mallet. Repeat the same steps for the other handle. 

Step 12: I put the weighted sleeve on the side, slightly above the handle. I use a square to mark both 4x4s and make sure they’re even. Then attach the flange and screw in the pipe. 

Step 13: When you’re done, this is how they should look.

Step 14: Disassemble the casters and lay them on the 2x6s to mark where to drill. 

Step 15: You’ll want to make sure this line-up.

Step 16: I pre-drill the holes for the bolts with my drill press.

Step 17: I follow that up with a 1/2 inch deep hole with a 1” Forstner bit. This is, so the bolts sit flush when they go in. 

Step 18: Put the bolts in and tighten the nuts. 

Step 19: Attach the 4x4s to the casters. When the bolt goes in, it is snug. This is what I want to prevent wobbling during use. 

Step 20: My rack has 1-inch holes, so I use 1-inch bolts. These are also a snug fit. I wouldn’t recommend using hitch pins for this because you want the connection to be tight. Otherwise, they’ll be wobbly. 

Step 21: If your holes line up correctly, they should go right in.

Step 22: For the finishing touch, I add paint and wood stain to match the DIY power rack I am working on. 

The finished product looks pretty great.

More Notes

I’m not a structural engineer. I know these bolts will hold, and I know these 2×6 pieces are strong enough. The only thing I don’t know about is the weight-bearing capacity of these casters in this position. They’re rated for 350 pounds each when appropriately used, but this is not the intended use. Proceed with caution when adding weights.

When I posted the prototype on Instagram, a few people asked if they could be mounted to the front of the rack. The incline press movements and the pull movements were great and allowed for a wide range of motion, but any kind of shoulder press was out of the question. 

My suggestion, if you want to mount on the inside but don’t have a 3×3 rack, is to use a combination of bolts and u-bolts, sort of like how Jaykofalltrades did it with this landmine. I would add a bolt going through the rack and one u-bolt. The size of the u-bolt will depend on your rack, but if you’ve made it this far, I have faith that you can figure it out.