mft/3 protractor detent pin slop & pin jumps out of detent

[cctrader2000]

The spring loaded pin in the protractor head of my mft/3 does not fit well.  After removing the pointer structure holding the pin and the pin naturally pushed out as far as it will go, manually I can move the pin left/right and forward/backward in it's drilled hole.  With the fence attached this pin movement translates into approximately a millimeter of fence movement at the table edge.  This occurs while pushing gently on the end of fence.  Is this kind of slop normal?

Furthermore, if you push lightly on the end of the fence, the pin jumps out of the detent.  Looking at the pin, the end has a 45 deg chamfer and does not go down into the tapered cut on the protractor, it just rides on teh rounded top of the angle cutouts.  I would thinj the spring loaded pin would be a "wedge" fit into the protractor detent cutouts.  Is this the correct operation of the detent pin?

 

[peter halle]

It is designed to do what it is doing.  You can put a finger on the top of the black knob to positively index it prior to locking in into place.  If you don't want the knob to fall into the detents, lift it up and turn 90 degrees.  It will then be disabled.  Also don't forget to use the outboard clamp on the fence, otherwise there is flex.

Hope this helps!

Peter

 

[cctrader2000]

Peter,

Appreciate the info, but...

Just went out and pressed down on black knob.  Unfortunately, even though the chamfered end of the pin registers in the top of the slot (not in the slot), it does not affect the movement of the fence because the hole is too big for the pin.  It actually makes a clicking noise as the fence is rotated about the detent position and the pin hits each side of the hole.  The pin is never is deep enough into the detents to prevent the fence from moving.  Simply gently moving the fence causes the pin to drop in and pop out as the fence is moved +/- 45 deg.  What is the point of a tapered detent slot if the shape of the pin does not take advantage of it to firmly lock into each detent.  I do not have to rotate the knob 90 deg to move the fence to any position; with minimal pressure, I can select any position with the spring pressing the pin down.

I have several miter gauges and sliding tables each with different detent type angle fence systems.  There is always a crisp snap at each detent and zero play when in the detent.

Surely there is some specification about the pin fit into the hole on the protractor pointer assy.  Regardless, the slop is unacceptable (approximately 1/16 inch over two feet) and I will contact Bob Marino for his resolution of the problem.

Thanks for your response,
cctrader2000

 

[peter halle]

Here is a video that might be of assistance.  Sometimes I don't explain well.  MFT video

To fast forward to the fence go to about the 7 minute mark.

Peter

 

[JBird]

The end of that video shows the loosening of the two bolts above the detent pin for the purposes of calibration. What it doesn't show is that by pulling the pin's assembly downward before before the bolts are re-tightened you can reduce the play in the detents.

 

[cctrader2000]

Peter,

I appreciate the video.  I thought the protractor head behaved like my compound miter saws and table saw miter gauges ie as the miter is moved through its range it latches at each detent and requires a separate mechanical action to bypass detents.  You are absolutely correct that the mft/3 protractor is able to slide across detents without latching.

Tried JBird's suggestion of pulling the pin's assembly downward before before the bolts are re-tightened but unfortunately same results.  I can hold the pin assy in my hand and "wiggle" the pin in its hole enought to hear a clicking sound as it moves left/right.

The play (slop) in the pin fit on my protractor head still results in a 1/2mm to 3/4mm ambiguous range at the edge of the table (approximately 24in); this is not mechanical flex.  While this seems small (much much less than 1 deg), crosscutting 24in plywood might mean that cutting with the "play" preloaded CCW on one cut and preloaded CW on a later cut could result in a >1mm error.  Right now I am always preloading CW when calibrating and after changing angles using the detent.  Will probably buy a new Support (489181) just to see if this is a continuing problem and a design expectation due to tolerance buildup or a quality problem.  Other than that, the 90 deg crosscuts are true after calibrating with my Woodpecker 18" precision square.

Thank ya'll for the help,
cctrader2000

 

[cctrader2000]

Update---
Talked to Festool customer support (nice folks) about the pin assembly.  They had one in hand and said it had some play between the pin and the hole in the pointer housing.  They sent me one and it also has the same play as my original one.  I wil just continue to lightly preload clockwise after the pin seats itselfin a detent and calibrate using the same process and before I lock the protractor head down.  It is then dead on.
Thanks to all

 

[peter halle]

Glad to see that you contacted them and although the situation did not work out as well as you wanted, you are still smiling - I think!

Peter