All Lever FP1 Power Feed Shear Pin Manufacture
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  1. #1
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    Default All Lever FP1 Power Feed Shear Pin Manufacture

    Hi everyone. I have a late 50's FP1 with levers that the power feeds have stopped working. I was lowering the table using the power feed when it stopped moving. I have noticed the Z axis sometimes locks by itself when I lower the table towards the floor. This has happened a couple of times now but have not been able to figure out why. I believe it is the Z lock the is preventing it from moving but can not be sure. Both the X and Z have stopped working and I believe the power drive shear pin is sheared. I only have the top side of the shear pin so I do not know the dimensions needed to make another.
    I was wondering if I could make my own shear pin and if so what are the dimensions? Should I follow a specific procedure when replacing the shear pin?

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    Hi All,

    Degull, Before you replace the shear pin you should try to find out what is overloading your Z axis feed! Can it be that there is too much friction in the Z axis slideways? Has it become more difficult to raise the table using the handwheel? could it be the bevels?

    If you have the top part of the shear pin then you can measure it and make a new one from very soft mild steel. If you use too tough a steel you can run the risk of feed bevel gear failure! The pin is only in single shear so does not need to be long. You can eject the broken end of the pin by aligning the hole in the collar with the hole in the shaft and push it out with a pin punch or length of round bar of the correct diameter. The pin is not a tight fit in it`s bore and is held in place with the spring steel clip on the outside diameter of the collar.

    Good Luck

    Alan

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    The Z axis is smooth now. I can lower and lift the table using the hand wheel with very little effort. The Z axis lock is suspect but I can’t duplicate the Z axis freeze up problem. It has happened twice before and if I recall correctly, it happened when I was lowering the table closer to bottom of the Z travel.

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    Quote Originally Posted by Degull View Post
    I was wondering if I could make my own shear pin and if so what are the dimensions?
    Yes, you can make your own. Use free-cutting steel. According to the owner's manual, the pins are made from 9S20K, currently designated as 11SMn30 or 9SMn28 or SAE 1213/1215 or 1.0715. This is a free-cutting steel, with relatively low carbon (.11%) and high sulpher (0.30%) content often called "Automatenstahl" in German.

    You can also purchase these from Franz Singer, in packs of five or ten. Search German Ebay for "Abscherstifte Deckel Fräsmaschine" to find these. If you buy a pack of ten (this item) you also get a replacement retention spring and a replacement rivet for holding the retention spring in place.

    My 1964 FP2 came with a pack of 50 of these shear pins (plus two replacement retainer springs and two rivets for fixing them in place). So if you want I can measure one and post the dimensions here. You need to make the body an easy sliding fit in the mounting hole, and the head large enough to retain the pin under the spring. The length should be long enough that the end of the pin approximately reaches the axis of the cylindrical shear-pin holder.




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    I am going to order some shear pins from Singer but it is a long way from Germany. If you can post the shear pin dimensions I would appreciate it!

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    Quote Originally Posted by Degull View Post
    If you can post the shear pin dimensions I would appreciate it!
    Sorry I was slow to do this, I kept forgetting to measure one.

    The pins have an overall length of 15.1mm. Of this, 12.4mm of length ("the body") has a diameter of 2.95mm, and the remaining 2.7mm of length ("the head") has a diameter of 4mm. Chamfer both ends 45 degrees as shown in the photo above.

    PS: note that the shear pin does NOT go into the "larger hole" side of the outer sleeve. It goes into the opposite side, so the head is sitting on top of the "smaller hole" side of the sleeve. Some discussion of this point can be found in this thread.
    Last edited by ballen; 04-19-2018 at 04:40 AM.

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