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Cam-Arm Tubing Cutter: Two Swinging Arms Keep the Wheel and Rollers Evenly Round Any Tube (Lutsker, 1959)
Simon Lutsker · Public domain
Forge

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Forge

13. November 2026NO
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Cam-Arm Tubing Cutter: Two Swinging Arms Keep the Wheel and Rollers Evenly Round Any Tube (Lutsker, 1959)

Simon Lutsker of Shaker Heights, Ohio, received US 2,870,536, dated 27 January 1959, for a tubing cutter that grips small and large tubes equally well. The wheel turns under a housing at the foot of a guide. A block slides up the guide on a screw. Two arms hang from the block, each with a roller at its lower end. Springs press the arms' curved cam edges against rollers on the housing. As the screw draws the block up, the arms swing inwards or outwards, so the wheel and the two rollers stay about evenly spaced round the tube, whatever its size. We worked out the cam so the three contacts are exactly 120 degrees apart. The curve comes out as an arc, as in his patent. All sizes are ours.
Advanced
About 4 days

Instructions

1

Three points evenly round

Loading Jupyter Notebook...
2

Read US 2,870,536

"Irrespective of the size of the tubing which is being cut, the points of engagement of the cutter wheel 21 and support rollers 32 with the tubing will always be substantially equidistant from each other circumferentially of the tubing."
3

Print the template

The arm plate with its cam edge, the housing and the guide block at 1:1, with holes, slots and sizes. print at 100 % (check the 50 mm bar).
Design FilePDFCC0 - Free
Download Model
4

Cut the arm plates

Glue four copies of the arm outline on 3 mm steel plate. Saw and file them to the line, taking the cam edge slowly and checking it against the template. Clamp them in a stack and drill the 4 mm pivot and roller-pin holes and the two 3 mm holes through all four together.

Materials for this step:

Mild Steel PlateMild Steel Plate1 piece

Tools needed:

HacksawHacksaw
File SetFile Set
Needle File SetNeedle File Set
Drill PressDrill Press
Machine ViceMachine Vice
Drill Bit SetDrill Bit Set
Center PunchCenter Punch
Bench ViseBench Vise
Digital Caliper 6-InchDigital Caliper 6-Inch
5

Make the housing

From 30 x 20 flat bar, saw a block 64 mm long and file it to 28 x 18 mm, leaving the two ears below its middle. Saw the forked ends: two cuts 14.4 mm apart, 20 mm in from each end, and break out the middle. Saw and file a 7 mm slot up between the ears for the wheel. Drill the 5 mm shaft hole across the ears, the 4 mm housing-roller pins across the forks, and the 4 mm rivet hole. File a groove 20 mm wide and 3 mm deep down each face for the guide's legs.

Materials for this step:

Mild Steel Flat BarMild Steel Flat Bar1 piece

Tools needed:

HacksawHacksaw
File SetFile Set
Drill PressDrill Press
Machine ViceMachine Vice
Drill Bit SetDrill Bit Set
Bench ViseBench Vise
Digital Caliper 6-InchDigital Caliper 6-Inch
ScriberScriber
6

Make the block and the guide

Saw the guide block from the same bar, 60 x 18 x 28 mm, with forked ends from 14 mm out, the 4 mm pivot holes, the 3 mm spring-pin holes and the leg grooves. Drill 8.5 mm up its middle and tap M10. Bend a 20 x 3 mm flat bar into an inverted U with its legs 22 mm apart inside and 69 mm high, and drill a 10.5 mm hole in its top.

Materials for this step:

Mild Steel Flat BarMild Steel Flat Bar2 pieces

Tools needed:

HacksawHacksaw
File SetFile Set
Drill PressDrill Press
Machine ViceMachine Vice
Drill Bit SetDrill Bit Set
Tap and Die SetTap and Die Set
Bench ViseBench Vise
Ball Peen HammerBall Peen Hammer
Digital Caliper 6-InchDigital Caliper 6-Inch
7

Turn the rollers and the wheel shaft

Turn two housing rollers 10 mm across and 14 mm long, and two lower rollers 12 mm across and 7.6 mm long, from mild steel bar, all bored 4.2 mm. For the wheel shaft, turn a 6 mm rod to 5 mm, leaving a 6 mm head, file a flat on the head, and turn a groove near the other end.

Materials for this step:

Mild Steel Round BarMild Steel Round Bar1 piece
Mild Steel RodMild Steel Rod1 piece

Tools needed:

Metal LatheMetal Lathe
Lathe Chuck 3-JawLathe Chuck 3-Jaw
Lathe Cutting ToolLathe Cutting Tool
Parting ToolParting Tool
Drill Bit SetDrill Bit Set
File SetFile Set
Digital Caliper 6-InchDigital Caliper 6-Inch
8

Turn the cutting wheel

Chuck a tool steel bar and face it. Turn the end to 20 mm across for 10 mm, centre drill and drill a 5 mm hole 10 mm deep, and turn the edge to a 50 degree vee, 25 degrees each side, sharp in the middle of the 6 mm width. Part it off 6 mm long and take the burr off the hole.

Materials for this step:

Tool Steel BarTool Steel Bar1 piece

Tools needed:

Metal LatheMetal Lathe
Lathe Chuck 3-JawLathe Chuck 3-Jaw
Lathe Cutting ToolLathe Cutting Tool
Parting ToolParting Tool
Center Drill SetCenter Drill Set
Drill Bit SetDrill Bit Set
Digital Caliper 6-InchDigital Caliper 6-Inch
Safety GlassesSafety Glasses
9

Harden and temper

Heat the wheel to a cherry red, until a magnet no longer sticks, and quench it in water, moving it about. Rub it bright with a stone, warm it on a piece of steel plate over the fire, and quench again as soon as it turns a light straw colour.

Tools needed:

ForgeForge
Forge TongsForge Tongs
Small MagnetSmall Magnet
Quench BucketQuench Bucket
WaterWater
Sharpening StoneSharpening Stone
Welding GlovesWelding Gloves
Safety GlassesSafety Glasses
10

Make the springs

From spring steel strip, cut two strips 8 mm wide and 30 mm long for the arm springs, and one 6 mm wide and 25 mm long to hold the wheel shaft. Bend each arm spring so it presses on its arm's spring pin and pushes the arm outwards. Drill a hole in the end of each for its pin or screw.

Materials for this step:

Spring Steel StripSpring Steel Strip1 piece

Tools needed:

HacksawHacksaw
File SetFile Set
Drill PressDrill Press
Drill Bit SetDrill Bit Set
Bench ViseBench Vise
11

Make the screw

Cut 90 mm of M10 threaded rod. Lock two nuts together 25 mm from its top as the flange. Put it up through the guide's top hole, add two washers as the spacer, then a nut locked with a second one. Drill a 6 mm hole across the top end and fit a 70 mm piece of 6 mm rod as the T-handle.

Materials for this step:

Threaded RodThreaded Rod1 piece
Hex NutHex Nut4 pieces
Flat WasherFlat Washer2 pieces
Mild Steel RodMild Steel Rod1 piece

Tools needed:

Adjustable SpannerAdjustable Spanner
Drill PressDrill Press
Drill Bit SetDrill Bit Set
HacksawHacksaw
Ball Peen HammerBall Peen Hammer
12

Assemble

Pin each arm pair together with its lower roller between the plates, and with short tubes as spacers on the pivot and spacer pins. Pin the arms into the block's forked ends. Fit the housing rollers in the housing's forks and the wheel on its shaft, with the flat spring screwed to the housing and sitting in the shaft's groove. Screw the block onto the screw, feed the arms down through the housing's forks inside its rollers, and rivet the guide's legs into the housing's grooves. Pin the arm springs to the block. Oil every pin and the screw.

Materials for this step:

Steel Dowel PinSteel Dowel Pin8 pieces
Steel RivetsSteel Rivets1 piece
Socket Head Cap ScrewSocket Head Cap Screw1 piece

Tools needed:

Ball Peen HammerBall Peen Hammer
Center PunchCenter Punch
Bench ViseBench Vise
Hex Key SetHex Key Set
Cutting OilCutting Oil
13

Cut a copper tube

Mark a copper tube and hold it in a vice with soft jaws, or by hand for small tubes. Turn the handle to open the arms, put the cutter over the tube, and turn it back until the rollers lift the tube against the wheel. Check by eye that the wheel and rollers look evenly spaced. Turn the cutter once round, give the screw about a quarter turn, and go on until the tube parts. The wheel should run in its own groove; the end should be square and not squeezed oval. Clean the inside of the end with a deburring tool.

Materials for this step:

Copper TubeCopper Tube1 piece

Tools needed:

Bench ViseBench Vise
Deburring ToolDeburring Tool
Digital Caliper 6-InchDigital Caliper 6-Inch
14

Troubleshooting

Cam-arm tubing cutter troubleshooting.

Flow

Loading...
15

History and honest limits

**Simon Lutsker** of Shaker Heights, Ohio, US 2,870,536, dated 27 January 1959, filed 26 August 1957. He claimed "a guide block mounted for movement along said guide member and movable by said screw means, a pair of cammable members pivotally secured to said guide block" and the springs pressing their "arcuate cam surfaces" against the housing rollers. He said the contacts stay "substantially" equidistant; ours are set exactly 120 degrees apart. The patent gives no sizes or cam radius; all of ours are ours.

Materials

13

Tools Required

29

Design Files

1

This blueprint makes

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Tube Cutter

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