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Semi-Automatic | Pneumatic Underpinner

Product Number: 178690006CE

The U-400S has been designed for ease of operation and is particularly well suited for joining frames up to 80mm in width.

Supplied with a tilting floor stand, the machine can be operated from the front or back and has a three stage pneumatic foot pedal that activates the Horizontal Clamp and Vertical Clamp securing moulding during the joining process.

After the framer sets the two position stops for measuring the max distance between strokes, a hand lever is then used to position and actuate V-Nail driver inserting V-Nails anywhere along the pre-set stroke distance. 

Former Model Reference - Alfamacchine M44

Purchase Package
(1) 7mm Nail Head
(1) 10mm Nail Head
(1) 12mm Nail Head
(1) Single Vertical Positive Placement Clamp
(1) Single Metal Pressure Plate
(1) Magnetic Base for Clamping System
(1) Blue Rubber Pad (SW)
(1) Yellow Rubber Pad (SW)
(1) Black Rubber Pad (SW)
(1) Round Pressure Pad - Felt
(1) Adjustable Fence - 3 Knobs
(1) Front Horizontal Clamp
(1) 4mm Allen Wrench
(1) 5mm Allen wrench
(1) 6mm Allen wrench
(4) Machine base levelers
(1) Floor Stand
(1) Machine Manual
Accessories and Replacement Items


Hand lever actuator for V-Nail Insertion

Replacement Nail Heads

P/N Description
394950010 3mm Nail Head
394950060 5mm Nail Head
394950020 7mm Nail Head
394950040 10mm Nail Head
394950030  12mm Nail Head
394950050 15mm Nail Head

Replacment Clamping Pads

P/N Description
397100003 Blue Replacement Rubber Pad (recommended for SW)
397100002 Yellow Replacement Rubber Pad (recommended for MW) 
397100001 Black Replacement Rubber Pad (recommended for HW) 


Extension Wings


P/N Description
291165010 Extension Wings Kit


P/N Description
244120130 Magnetic Base for Clamp Assembly
242230300 Single Metal Pressure Plate
397100005 Magnetic - Single Metal Pressure Plate
298390390 Single Vertical Positive Placement Clamp
242230010 Round Pressure Pad, Felt
242230040 Round Pressure Pad, Vulkolan
243180020 Fixed Fence - 90°
Power Requirements

Compressed Air 4NI at 5 Bar
CE Compliant

Sales & Technical Documents
U400S_EN 1.png U-400S ALFA Sellsheet 11-10-15_Page_1.png

Instruction Manual   

- Italian Version

U-400S Literature

- Italian Version

Unique Performance Features

  • Handles up to 80mm wide moulding
  • Operator controlled arm allows framer to accurately position the Nail Head for inserting or stacking V-Nails anywhere along the frame joint
  • Uses both a vertical and horizontal clamping method
  • Adjustable working table height for operator comfort
  • Easy table tilt adjustment
  • Join either from back or front of machine
  • CE Compliant

Frame Joining Capabilities

Moulding Width
(min to max)

Moulding Height
(min to max)

Max Distance
Between V-Nails

6-80 mm)

6-80 mm

120 mm

Pre-set V-Nail
Position Stops

V-Nail Sizes

V-Nail Channel


3, 5, 7,10,12,15 mm

220 V-Nails/channel

Machine Dimensions & Weight

Length: 600mm (23 3/4")
Width: 560mm (22")
Height: 1350mm (53")
Weight: 90 kg (198lbs.)

Related Products

Alfamacchine Genuine - Power Twist® V-Nail

Alfamacchine Genuine - Power Twist® V-Nail

Alfamacchine Universal - Power Twist® V-Nail

Alfamacchine Universal - Power Twist® V-Nail

Contact Us

If you are an existing FBG Equipment Customer and are looking for Spare Parts, Cutting Blades and Wheels, or equipment accessories, please visit the company’s online store at

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