Incra LS Positioner adjustment

[Mario Turcot]

Totally out of no where that video was in my youtube suggestion... I swear I didn't search on it. I don't even have a MFT/3 table let alone an Incra Ls Positioner  [tongue]

I know some people were asking about how to be sure to be square with the Incra fence & the MFt fence and thought that the technique in that video was worth posting.

Incra LS Pos

 

[Lbob131]

I'am  intrigued  by  how  users  of  the LS positioner  can  get  such  close  fitting  accuracy  when making  box  joints  or  dovetails.
It seems to  be  just an accurate  tape  measuring  device  and  like  using a tape  measure,  totally  open  to user  error.

Surely a  good  dovetail  jig  will  be  more  accurate  and  faster?

 

[kevinculle]

The secret to the Incra positioners is a pair of toothed plastic racks with teeth spaced either at 1/32" or 1mm steps.  When you move the positioner to a position and engage the lock the toothed racks engage and the position is locked to within the tolerance of the rack teeth.  I have the Incra TS-III system on my table saw/router table extension and it will easily position the fence within a repeatable 0.002"-0.003".  It's the cat's ass.

 

[edwarmr]

The secret to the Incra positioners is a pair of toothed plastic racks with teeth spaced either at 1/32" or 1mm steps.

It’s actually a steel lead screw with threads every 1/32” or 1mm. The plastic teeth you’re referring to are on the incra miter gauge fences and the router fence itself but the ls positioner uses a steel lead screw that mates with steel threads in the positioner carriage for perfect incremental adjustments. The knob seen in the image allows 0.001” increment adjustments as well in addition to the 1/32” adjustments.

[attachimg=1]

 

[Lbob131]

I get  it now.
The accuracy  looks  incredible. [smile]

 

[kevinculle]

The lead screw is the fine adjustment to get the carriage zeroed to the blade when the plastic positioning racks are locked together.  The lead screw adjusts for accuracy at a particular setting but the racks provide the dead nuts repeatability that is the essence of the Incra system.

 

[MikeGE]

The lead screw is the fine adjustment to get the carriage zeroed to the blade when the plastic positioning racks are locked together.  The lead screw adjusts for accuracy at a particular setting but the racks provide the dead nuts repeatability that is the essence of the Incra system.

Do you have an LS positioner?  I have the 17 and 25 inch versions, and there are no plastic racks in either of them.  The lead screw mates with a metal rack in the positioner base.  The only significant plastic I can see on my LS positioners are the clear windows for viewing the scales.

 

[edwarmr]

The lead screw is the fine adjustment to get the carriage zeroed to the blade when the plastic positioning racks are locked together.  The lead screw adjusts for accuracy at a particular setting but the racks provide the dead nuts repeatability that is the essence of the Incra system.

Ditto to what [member=70363]MikeGE[/member] said. There are no plastic racks in the Incra LS Positioner. You must have a different Incra product from the past. The lead screw does everything with the Incra LS Positioner. Even the 0.001" adjustments are based on a partial movement around the lead screw. Since 1/32"=0.031" you can achieve very close to a 0.001" adjustment by turning the fine adjustment knob 1/32 of a full rotation (see the picture in my post above).

 

[edwarmr]

[member=60975]kevinculle[/member]
I just saw that you have the Incra TS-III. This is an older Incra positioner before the LS Positioner came out. I looked up pictures of the Incra TS-III and it has plastic racks. The LS Positioner does not have plastic racks.

This is the Incra TS-III
[attachimg=1]

 

[MikeGE]

[member=60975]kevinculle[/member]
I just saw that you have the Incra TS-III. This is an older Incra positioner before the LS Positioner came out. I looked up pictures of the Incra TS-III and it has plastic racks. The LS Positioner does not have plastic racks.

Thanks for the explanation!  I assume the metric version of the TS-III has red plastic racks instead of black.

 

[edwarmr]

Thanks for the explanation!  I assume the metric version of the TS-III has red plastic racks instead of black.
[/quote]

You’re welcome! I think you’re right on the red racks for metric.