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How to use the Makita JS1601 shear with Magnetic Guide
How to make the Magnetic Guide.
How to Adjust the Blade Clearance on the Makita JS1601 Shear




The power shear (based on the Makita Model JS 1601) provides a means for cutting sheetmetal in such a way that very little distortion is left in the workpiece.  This is possible because the shear removes a waste strip, about  4 mm wide, and most of the distortion inherent in shearing sheetmetal goes into this waste strip. 
For use with a Magnabend the shear has been fitted with a special magnetic guide.

There is considerable synergy when this shear is used in combination with a Magnabend Sheetmetal Folder;  the Magnabend provides both a means of holding the workpiece fixed while being cut and also a means for guiding the tool so that very straight cutting is possible.  Cuts of any length can be handled in steel up to 1.6 mm thick or aluminium up to 2 mm thick.
To use the tool first place the sheetmetal workpiece under the clampbar of the Magnabend and position it so that  the cutting line is exactly 1 mm in front of the edge of the Bending Beam.
A toggle switch labelled “NORMAL / AUX CLAMP” will be found next to the main ON/OFF switch.  Switch this to the AUX CLAMP position to hold the workpiece firmly in position.
Position the shear at the right-hand end of the Magnabend and ensure that the magnetic guide attachment engages on the front edge of the Bending Beam.  Start the power shear and then push it evenly along until the cut is completed.

Notes:

1. For optimum performance the blade clearance should be adjusted to suit the thickness of material to be cut.    Please refer to the instructions below.
2. The shear will cut more freely if a few drops of lubricant ,e.g. WD40, is added to the blades.

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The magnetic guide for the Makita shear was originally developed by Magnetic Engineering but has not been commercially produced since the Magnetic Engineering business was sold.

I am now publishing information on how to make and fit the magnetic guide in the hope that it will be picked up and manufactured by a current Magnabend machine manufacturer.
The information could also be used by any individual who wants to implement this tool and who has the  facilities needed to produce it.

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The first step is to purchase the Makita JS1601 tool (or the Makita DJS161Z which is the battery version).
This is a relatively expensive tool but it is of very good quality.

The next step is to make and attach the Magnetic Guide Assembly.
The shear, with the guide, is shown (upside down) in the picture below:-

The Guide Assembly consists of the following parts:

1. The Arm, made from 16 mm square aluminium bar,
2. The T-Piece, made from T-section aluminium extrusion,
3. A Spacer piece, made from 2 mm thick aluminium sheet,
4. Two neodymium magnets 12mm diameter by 10mm long,
5. Four M5 x 12 countersunk screws and
6. Two roll pins 3mm diameter by 16mm long.

Drawing for the Arm:-



Drawing for the T-Piece:-



Drawing for the Spacer:-





Photo of the setup for maching and drilling the Makita Shear:-



Procedure for modifications to the Makita shear:

1. Remove the the 2 fixed blades from the shear,
   There is a shim (0.5mm thick) under one of the blades. By default the shim is inserted under the left-hand side blade (right-hand side when viewed from the under side of the shear) and this will cause the waste strip to spiral out towards the right. (When you put the blades back you could swap sides for the shim if desired).
2. Clamp the shear in the milling machine so that the plane defined by the blades is horizontal,
3. Machine a flat on the shear in the area where the mounting holes will be drilled.
   (Only a small depth will need to be machined).
4. Drill 2 holes, diameter 4.2mm, and tap a thread to suit M5 screws as shown in the picture above.
   Note: These holes need to be accurately referenced to the blade mounting holes (which are 20.0mm apart).

Assemble the Neodymium magnets into the Arm.
Depending on size variations the magnets may be a tight fit into the arm or they could be a bit looser.
If the fit is very tight then they can be treated as an interference fit and pressed in with a vice.
Otherwise Loctite can be used to fix the magnets into place.
The magnets should be inserted until flush with the surface of the Arm.

Assemble the T-Piece to the Shear:
Place the Spacer piece on the shear and the T-piece on top of it then insert  2 M5 screws.  Initially do not fully tighten the screws. This will allow a small adjustment of the alignment of the T-piece.
Hold a small straight edge against the side of the T-piece. It should just slightly interfere with the edge of the shear blade because the blade is 4mm wide whereas the T-piece is only 3mm thick.
If necessary bias the alignment of the T-piece so that it is symetric with the blade and then fully tighten the screws.  Check the alignment again.




Assemble the Roll Pins:
The alignment of the T-piece is locked by a pair of pins.
Using the T-piece as a guide drill the 3mm holes for the roll pins.  A pistol drill should suffice for this job.
Insert the roll pins and tap them in until flush.

Assemble the Arm to the T-Piece:
Fasten the Arm to the T-Piece using 2 M5 countersunk screws.

This completes the Magnetic Guide and its attachment to the Makita Shear.

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For optimum cutting performance it is important to adjust the blade clearance to suit the thickness of the sheet metal being cut.
The shear is supplied with a set of 3 "feeler" gauges as shown here:

The numbers on the gauges correspond to the intended metal thickness to be cut.

The actual thickness of the gauges themselves is as follows:

-  "1.5" gauge is 0.3mm thick.
-  "1.0" gauge is 0.2mm thick,
-  "0.5" gauge is 0.1mm thick,  

If you loose the original set then you can use an ordinary set of feeler gauges instead.

The shear is also supplied with a 3mm Allen key which is stored with the tool as shown on the left.
This key is used to adjust 2 screws, one on either side of the jaws.

One of the screws is a jacking screw which pushes the jaws apart.  
The other screw is a clamping screw which pulls the jaws together and thus locks the setting.



To adjust the blades start by loosening the Clamping Screw.  Half a turn is enough.
Then turn the Jacking screw - clockwise to increase clearance, or counter-clockwise to decrease clearance. Typically only a quarter of a turn, or less, will be needed on the Jacking Screw.
(The pitch of this screw is 0.8mm per turn).

Next retighten the Clamping Screw.

Finally check the blade clearance by trying which feeler gauge will slip in between the edge of the moving blade and the edge of one of the fixed blades.
Check the clearance on both sides of the moving blade and take the average as the effective clearance.

If necessary readjust the screws to obtain the desired clearance.

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