Using cross stop for medium mortise setting?

[fritter63]

Tried to search for this topic but couldn't find anything....

I was trying to figure out how to use the cross stop for cutting the mating set of mortises using the medium mode (edge joining).

This what makes sense to me:

* FOR THE SAKE OF THIS EXAMPLE, ASSUME THE CROSS STOP PROVIDES 100% accuracy on placing next mortise *

  - Medium setting is 6 mil wider
  - distance gauge shows distance form edge of pin (ie, previous mortise edge) to center of cutter (right?)
  - So, offset is 3 mil more than if using narrow setting
  - To use cross stop:
        - On first set, use narrow setting, cross stops set at 100 mil (just an example)
        - On second set, use medium setting, cross stop set at 97 mil

I would think that would set the second row all centered on the first row, but a test cut didn't get that, the wider ones were still "creeping"
further and further off center. This was more than would be accounted for by any inaccuracies in the pins.

What am I missing?

 

[PaulMarcel]

Unless I'm remembering incorrectly, the medium setting is 3mm wider.  The large setting is the 6mm wider setting.  That would cause the creeping.

 

[fritter63]

From the manual:

" In the middle position, the mortise slot will be 6 mm wider than the Domino tenon. In the widest position the mortise slot will be 10 mm wider than the Domino tenon."

So I think my math should still be correct?

 

[Wood_Junkie]

As you quoted "... wider than the Domino tenon"

This is affected by the bit being used.  Since the mechanism moves the same amount, regardless of bit diameter, you get different widths and “thickness” of the slot.

For example, the 5mm bit will have a mortise of width XX (and 5mm “thick”).

So the 10mm cutter bit would have a medium width setting mortise of XX+2.5mm (one-half of the bit diameter difference).
A 6mm bit would have a mortise width of XX+0.5mm
A 8mm bit would have a mortise width of XX+1.5mm
A 4mm bit would have a mortise width of XX-0.5mm

Since the medium width just increase the side-to-side movement by a fixed amount, the bit difference are the same.

Are these on par with the creep you’re seeing?  Which bit are you using?

 

[fritter63]

As you quoted "... wider than the Domino tenon"

This is affected by the bit being used.  Since the mechanism moves the same amount, regardless of bit diameter, you get different widths and “thickness” of the slot.

For example, the 5mm bit will have a mortise of width XX (and 5mm “thick”).

So the 10mm cutter bit would have a medium width setting mortise of XX+2.5mm (one-half of the bit diameter difference).
A 6mm bit would have a mortise width of XX+0.5mm
A 8mm bit would have a mortise width of XX+1.5mm
A 4mm bit would have a mortise width of XX-0.5mm

Since the medium width just increase the side-to-side movement by a fixed amount, the bit difference are the same.

Are these on par with the creep you’re seeing?  Which bit are you using?

I'm using the 6 mm bit.

I don't think it would work that way. The manual specifically says "6 mm wider than the DOMINO". Ie, this metric has already accounted
for the different dimensions of the bits, and that makes sense if the mechanism always moves the same amount. Ie, this equation is
agnostic of the actual width of the mortise in narrow setting, regardless of which bit is being used. Switching to medium causes the machine
to move an additional 3 mm to each side (for a total of 6 mm), and therefore that offset is consistent across all bit sizes.

Right?

 

[Brice Burrell]

...I would think that would set the second row all centered on the first row, but a test cut didn't get that, the wider ones were still "creeping"
further and further off center. This was more than would be accounted for by any inaccuracies in the pins.

What am I missing?

I wouldn't count on that.  I did some testing with my cross stops and found both were off in opposite directions.  After a few mortises the creep added up to not allow the tenons to fit.  You'll want to use the wider setting on both pieces to get yourself more room for error.  I generally use the widest setting to spare myself headaches. 

 

[tbellemare]

As you quoted "... wider than the Domino tenon"

This is affected by the bit being used.  Since the mechanism moves the same amount, regardless of bit diameter, you get different widths and “thickness” of the slot.

For example, the 5mm bit will have a mortise of width XX (and 5mm “thick”).

So the 10mm cutter bit would have a medium width setting mortise of XX+2.5mm (one-half of the bit diameter difference).
A 6mm bit would have a mortise width of XX+0.5mm
A 8mm bit would have a mortise width of XX+1.5mm
A 4mm bit would have a mortise width of XX-0.5mm

Since the medium width just increase the side-to-side movement by a fixed amount, the bit difference are the same.

Are these on par with the creep you’re seeing?  Which bit are you using?

Am I reading this wrong?

If I use a 10mm bit, the mortise on the same width setting is 5mm wider than using a 5mm bit. It's 2.5mm per side.

Tom

 

[Wood_Junkie]

As you quoted "... wider than the Domino tenon"

This is affected by the bit being used.  Since the mechanism moves the same amount, regardless of bit diameter, you get different widths and “thickness” of the slot.

For example, the 5mm bit will have a mortise of width XX (and 5mm “thick”).

So the 10mm cutter bit would have a medium width setting mortise of XX+2.5mm (one-half of the bit diameter difference).
A 6mm bit would have a mortise width of XX+0.5mm
A 8mm bit would have a mortise width of XX+1.5mm
A 4mm bit would have a mortise width of XX-0.5mm

Since the medium width just increase the side-to-side movement by a fixed amount, the bit difference are the same.

Are these on par with the creep you’re seeing?  Which bit are you using?

Am I reading this wrong?

If I use a 10mm bit, the mortise on the same width setting is 5mm wider than using a 5mm bit. It's 2.5mm per side.

Tom

No, I think I wrote it confusingly... I didn't clarify I was referring to one "side".  Meaning, the referenced end of one mortise (for the cross stop) would be 2.5mm further than with a 5mm bit.
I was also using a variable "XX" to indicate the mortise width using a 5mm bit, as the baseline value. 
I was trying to indicate how the cross-stop's reference distance would vary by bit.

So, using a 10mm bit, you get the width XX+2.5mm (laterally on one side... 5mm total width increase), as you said.