• We invite you to join UKWorkshop.
    Members can turn off viewing Ads!

Incra LS 17 positioner

UKworkshop.co.uk

Help Support UKworkshop.co.uk:

Spectric

Established Member
UKW Supporter
Joined
19 Feb 2015
Messages
2,655
Reaction score
1,209
Location
North Cumbria
Hi all

Well any one got one or knows the overall dimension from the face of an attached wonder fence to the far end of the positioner? This determines how much depth my new bench will require and influence some key design issues.

If @Peter Sefton is around he probably knows this overall length, thanks in anticipation.
 

MikeK

Moderator
Staff member
Moderator
Joined
9 Apr 2017
Messages
1,959
Reaction score
830
Location
Germany
Roy, I hope this helps.

The Wonder Fence adds 124mm to the front of the basic LS 17 face and 87mm to the front of the standard Incra fence.

LS-17-1.jpg



The overall length of the positioner with the Wonder Fence and LS 17 positioner is 778mm and the standard fence and LS positioner is 691mm. I have the steel rule set so "zero" when the face of the Wonder Fence is over the center of the router arbor and can move the fence back 280mm from the center of any router cutter. If I remove the Wonder Fence and set the "zero" when the face of the standard fence is over the center of the router arbor, I have 367mm of depth.

Since the T-track profile on the face of the Wonder Fence and standard fence is identical, there is no need to use the Wonder Fence when the router bit is outside the vacuum opening. I've only needed to do this once when I needed the extra depth. When I removed the Wonder Fence, I left the steel tape set for the Wonder Fence and slid the white tape to the new reference point for the standard fence.



LS-17-2.jpg


My Incra table was pre-drilled for the LS 17 positioner, so Incra designed it so half of the positioner base extends beyond the end of the table. The four bolts holds it firmly to the table top.If you think you will need more range than 367mm, you might want to consider the LS 25 positioner and a larger table.
 

Spectric

Established Member
UKW Supporter
Joined
19 Feb 2015
Messages
2,655
Reaction score
1,209
Location
North Cumbria
Thanks Mike, brilliant info as I am looking at a new workbench router combination and with a normal fence arrangement you do not require a lot of table depth but with the positioner it changes everything and I am tight on space so need to get this new idea right. So far looked and thought about probably every router fence design going and even delved into some past ideas but for repeatable precision nothing compares to these Incra positioners. I am looking at using an attachment plate, either make one like Dennis in hooked on wood or the Benchdogs plate and this solves the range as I can just relocate so if anything a shorther positioner would be even better so less to protrude to the rear.
 

MikeK

Moderator
Staff member
Moderator
Joined
9 Apr 2017
Messages
1,959
Reaction score
830
Location
Germany
I like the idea of using a mounting plate like Dennis on an MFT-style table. After looking at my LS 17 and LS25, I think a capable machine shop could easily convert the LS 17 into an LS 10, or any other shorter size that will work with the 96mm hole pattern on the work surface.

The lead screw would be the difficult part (for me) to shorten, but the extrusion would be simple to cut and the end plate could be reused.

This part could remain untouched.

LS-17-3.jpg



Two views of the opposite end showing the end plate and the end of the lead screw.

LS-17-4.jpg


LS-17-5.jpg
 

Spectric

Established Member
UKW Supporter
Joined
19 Feb 2015
Messages
2,655
Reaction score
1,209
Location
North Cumbria
Looking at the drawing I am supprised at the finish that Incra has accepted on that end plate, you can see the cut marks which looks to be steel. I cannot see any reason why they did not cut this from alloy using CNC, probably a brought in component. I am currently drawing this up to see how things fit on my proposed new bench but also need to take into account the use of the cross sled right angle adaptor, excuse my description. My initial thoughts on the lead screw are that it appears that that black piece screws onto the thread and the nut secures, so if that is the case then shortening the lead screw should not be difficult but at present still doing the layout to ensure it would be a beneficial move or there are sufficient gains.
 

Spectric

Established Member
UKW Supporter
Joined
19 Feb 2015
Messages
2,655
Reaction score
1,209
Location
North Cumbria
Rethinking that lead screw attachment, is the black area just throwing us off, it looks very thin almost like heatshrink but for what purpose. Perhaps the lead screw is internally threaded in which case shortening the other end would be a lot easier, here it looks like the adjustment knob is held on with a grub screw, but maybe some type of location on the lead screw, a flat or indent.
 

MikeK

Moderator
Staff member
Moderator
Joined
9 Apr 2017
Messages
1,959
Reaction score
830
Location
Germany
Roy, my curiosity got the best of me so I took off the end of my LS 25 to see how it was assembled. I hope these images are useful to you or anyone considering modifying the positioner.

This is the end plate. The black screw accepts a 1/8-inch hex key and uses a metric nut to lock it in place. It's function will be clear later, but it is used to preload the ball bearing that contacts the end of the lead screw.

LS-25-1.jpg


There are five 10-32 x 1-inch self-tapping machine screws holding the steel plate to the aluminum extrusion (four of the five screws shown).

LS-25-6.jpg


Here is an image of the steel plate and the screw.

LS-25-3.jpg


After removing the steel plate, I can see the black ring is just a spacer containing what appears to be white lithium grease and a steel ball bearing.

LS-25-2.jpg


When I removed the black spacer, the ball bearing is now visible.

LS-25-4.jpg


I didn't have any grease to apply, so I didn't clean up the end of the lead screw; however, I probed it and couldn't feel a dimple, so I assume the end of the lead screw is flat.

LS-25-5.jpg


I think you are correct about the grub screw in the adjustment knob. I didn't take an image of it, but there is what appears to be an identical black spacer between the lead screw and the front plate. I don't recall seeing an adjustment on the front plate, but didn't want to take my positioner apart any further to check.

The red adjustment knob's only function is to turn the lead screw in place. The black dial is a friction fit to the adjustment knob and rotates to allow the operator to set a new "zero" adjustment. The click stops for the increments are created by a spring-loaded bearing in the extrusion that contacts dimples in one face of the red adjustment knob.

LS-25-7.jpg
 

Spectric

Established Member
UKW Supporter
Joined
19 Feb 2015
Messages
2,655
Reaction score
1,209
Location
North Cumbria
Firstly this only applies if you have a small working area and have to work hard to get things to fit into a tight space where every inch counts. The drawing attached shows the Ls17 at it's two extremities with a wonder fence attached on a 800 wide and 850 deep footprint area which would suit nearly every task I currently do on my Kreg table but you need to allow space for 280mm (11 inches) of rear Ls17 positioner overhang with the fence fully back which is about 58mm behind the centre of the router, more than is needed but easier to deal with extremes then everything inbetween is allowed for. With the positioner fully forward, again to an extreme you have 170mm ( nearly 7 inches) of overhang. Based on these I may be looking at reducing the Ls 17 from 430mm to 300mm, but that sounds a lot of work for 5 inches but then that could change where the new bench will fit for most jobs. Mike, yes curiosity is a wonderful thing and takes things out of the unknown, so this confirms the black bush just locates the leadscrew and retains the ball to provide a thrust bearing to remove any linear slack which would detract from accuracy, my conclusion is leave this end of the lead screw alone and shorten the other end. Interesting to note the two black rods that act as bearings to support the lead screw. You can also see a lot of what looks like swarf around those thread holes, do you think this is just a case of not cleaning up properly after the threads were initially tapped?

Ls17.jpeg
 

MikeK

Moderator
Staff member
Moderator
Joined
9 Apr 2017
Messages
1,959
Reaction score
830
Location
Germany
You can also see a lot of what looks like swarf around those thread holes, do you think this is just a case of not cleaning up properly after the threads were initially tapped?
The five 10-32 screws are self-tapping, so I am confident threads were cut by the screws as the plate was attached. I doubt the manufacturing process included removing the plate to clean out the swarf. I didn't bother cleaning it out either since the channel is sealed on both ends.

You might consider the attachment of the positioner base to the table interface so it overhangs by half on the rear. This will give more range of depth without affecting stability. I have never seen the LS positioner base attached to a router table where the entire base is fully on the table. With the four 1/4-20 bolts and hardware supplied to attach the positioner base, it is very stable and is not the weak point in the system. Also, the vacuum channel in the Wonder Fence is not effective once the fence is moved sufficiently away from the cutter and becomes blocked by the material being cut. You can gain more working depth by removing the Wonder Fence when appropriate.

Unless there is a flat milled in the lead screw for the red adjustment knob grub screw, I don't think it matters which end is shortened. However, I would definitely cut the extrusion from the end opposite the adjusting knob so you don't have to worry about milling the slot for the knob and indexing ball. 😊
 

Spectric

Established Member
UKW Supporter
Joined
19 Feb 2015
Messages
2,655
Reaction score
1,209
Location
North Cumbria
Hi

When looking at the attachment plate, it is nice to see the 1920's waistline that Dennis used but put a bit more meat on it so it can have six mounting holes and not just four and now you have additional positions. Also add two more bench holes nearer the router plate and it allows the fence to be nearer the router when the wonder fence is not attached. Currently looking at space and moving things in my work area to help accomodate.
 

Attachments

Top