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Thread: Inca LS-25 Positioner for SC2 Classic Sliding Saw

  1. #1
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    Inca LS-25 Positioner for SC2 Classic Sliding Saw

    The SCM Minimax SC2 Classic is a great saw, but it could be better if I could rip from the slide as well as crosscut. After watching the YouTube videos of Sam Blasco use a positioner on his SCM CU 410, I decided to buy an Incra LS-25 positioner and expand my SC2’s abilities. This thread describes the build and calibration of the positioner in case anyone else is tempted.

    Here are the components and some of the tools I used to attach the positioner to my saw. The Incra positioners are available in 17, 25, and 32-inch versions, in both imperial and metric. I chose the 25-inch metric version.




    1. SCM Auxiliary table. This fits several models of SCM slider saws, and it attaches to the side of the slider wagon in a T-track.

    2. Incra LS-25 sub-base.

    3. Incra LS-25 rail.

    4. 60x30 aluminum extrusion used for the positioner fence.

    5. Mounting hardware for the LS-25 sub base.

    6. 100mm spacer block for the crosscut fence (explained later)

    7. Stop block for item 4.

    8. Homemade alignment plates to square the assembled positioner to the slider.

    9. 50x3mm aluminum plate used as a spacer for item 4 during assembly.

    10. Some of the tools. Not in the photo are the Starrett 386-24 straight edge, 13mm combination wrench, drill motor, 7.5mm drill, and countersink.


    Starting with the underside of the auxiliary table, here are the only moving parts. I’ll be removing the spring-loaded handles, as they are a nuisance to me and get in the way of making adjustments.




    Here is a detailed description of what the hardware does. There’s nothing in the saw manual describing this (at least that I could find), and there weren’t any instructions with the table. The table height and angle adjustments are done once and ensure the table is the same along any part of the slider wagon. When locked down, these adjustments ensure the table alignment is correct each time it is removed and reattached to the saw.




    Here’s another photo from the side of the table that joins the slider.




    And here is an exciting view of the underside of the table once it is attached to the slider wagon.




    It is important to set the height of the table so it is flush with the surface of the slider bed and also coplanar with the bed. In this photo, the left side of the table is lower than the right. I watch the Starrett straight edge while I slowly turn the adjusting screws to bring the table coplanar. It is easier to start with the left side too high and work it down than to try to raise it. The adjustment process requires a small turn of the two set screws followed by tightening or loosening of the T-track screws.




    After a few minutes of small adjustments, the table is level with the slider bed.




    I positioned the LS-25 on the auxiliary table in about the location I wanted. The maximum ripping width I will use with this is about 500mm. Any more than that, and I will use the crosscut fence to hold the work square to the blade.




    I put two strips of masking tape on the auxiliary table and marked the location of the mounting holes. I had a good reason for not making the middle holes centered between the other two holes, but by the time I drilled them, I had forgotten why I did that.




    The 7.5mm holes are drilled, deburred, and ready to loosely attach the LS-25 sub base.




    I did not use the 1/4-20 hardware that came with the LS-25. The bolt heads fit in the channel of the sub base, and they are a loose fit. The hardware I had left over from my MFT-style workbench was perfect.




    The LS-25 positioner is in place, and I can easily achieve rips of 500mm.

    Last edited by Mike Kreinhop; 11-27-2020 at 10:55 PM.

  2. #2
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    Now it’s time to align the positioner fence to the slider bed. I attached the two alignment plates (item 8 above) to the ends of the fence. Then I slowly pushed the fence and rail so the plates touched the edge of the slider bed. While I was doing this, I was also turning the sub-base slightly to ensure the rail stayed perpindicular to the slider bed. As the plates got closer to the slider bed, I flipped the sub-base lever to the first notch so I could use the micro adjust to dial the fence closer in 0.1mm increments. When both plates were touching the edge of the slider bed, I locked the sub-base lever and slowly tightened each of the four screws holding the base to the auxiliary table.




    After checking again that the fence was still square with the slider bed, I released the locking lever on the sub base and and moved the fence so it was just touching the infeed tips of the blade.





    Then I locked the sub-base lever and adjusted the scale tapes so they both indicated zero. The image appears to be upside down, but this is how it really looks in use.




    I attached the stop block (item 7 above) to the end of the fence for the next tests and checked for squareness. This is from the top looking down on the stop block. The block was also square to the slider bed.




    I used a piece of scrap to check the positioner settings. The first cut was just to put a clean edge on the board. After this cut, I flipped it over so the fresh cut was touching the fence, and set the distance to 17cm.




    The parallax error with my phone camera and my eyes don’t do this photo justice, but the cut is as close to 17cm as I can get it when checking with a 10x loupe.




    I made another test cut using the crosscut fence stop block and the positioner stop block. After cutting a clean edge, I ripped this board to 10cm. It was as accurate as the smaller board using only the LS-25 positioner.




    Next, I made another cut on the same board to rip it to 50mm. Here is where I discovered a design flaw the my crosscut stop block (item 6 above). I made this spacer because the crosscut stop block that is part of the saw cannot move closer than about 75mm to the blade. In order to rip smaller items, I need to offset the saw stop block by a known amount. In this case, I chose 100mm. Unfortunately, the T-track hardware of my space runs out of T-track at about the 75mm point. My next version will be a 200mm spacer with the T-track hardware farther from the end of the block so there are two bolts holding it to the crosscut fence.




    Overall, I am very pleased with this addition to my saw. I have some improvements to make, but it is fully functional now and will only get better. I also started on a Fritz and Franz jig this afternoon.

    One near-term addition will be fitting some of my Festool ratchet clamps to the T-track in the top of the slider bed so I can secure material for long and close cutting.
    Last edited by Mike Kreinhop; 11-27-2020 at 11:00 PM.

  3. #3
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    Thanks for sharing this Mike, appreciated the photos and detailed explanation.

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    That's a very good adaptation, Mike! While I typically use my Fritz and Franz jig for this purpose (and I try to do as much of my ripping with the material on the wagon as possible for the superior cut quality) the positioner idea is very interesting. I don't have that auxiliary table with my S215WS, but if I need to downsize my shop in the future, I'll likely move to an SC3 (or SC2) which at least the former comes with that small table in the standard configuration here. So I might leverage this idea, too, at that point. My original parallel jig was kinda sorta similar, albeit low tech and made of plywood, but set up in the same way, I'll add.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  5. #5
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    Very nice work, Mike. Will you be removing and reinstalling that auxiliary table each time you go to use the positioner? That is, will it stay permanently mounted to the auxiliary table?

    Like Jim, I typically just use my Fritz and Franz jig for ripping on my Hammer K3. However I do own a 17" LS Positioner, and have a way to rig it up in a similar fashion using a shop-made "table" for whenever I have to do a ton of rip cuts. It doesn't connect to an OEM auxiliary table because the table on the K3 is very finicky to install and align, so I haven't moved that since I got it installed. I also don't use the far outrigger-based fence very frequently since I have a small basement shop and only install the outrigger when I need it. I should revisit my mounting solution for the positioner though to see if I can devise something that goes on and off more readily.
    And there was trouble, taking place...

  6. #6
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    Thank you, Pat, Jim, and Steve!

    Steve, the auxiliary table is easy to remove and install if the LS rail gets in the way of normal crosscuts. The LS rail slides out of the sub-base, which makes the table easier to handle. Then I loosen the two T-track screws under the table and slide it out for storage. I bought two of the auxiliary tables, one for the positioner and one as additional support for sheet goods.

    Once the height and leveling adjustments for each table are locked in, no further adjustments to the table are needed, and it aligns with the slider top ever time. I can change out the two tables in less than a minute. Today I cut some large plywood sheets and had removed the positioner table. Later this afternoon, I needed to cut some strips of 5mm thick HDPE for my MFT-style workbench, so I put the positioner table back on and didn't have to repeat the alignment process. I accurately cut six 61.5mm wide strips of the meter-long HDPE sheet.

  7. #7
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    Steve, if one doesn't have the small miter fence mounted all the time like I do, removing that entire aux table only takes a few seconds.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  8. #8
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    I watched one of Sam's videos again and made another change that worked out better than using the entire fence and a stop block. Sam calls it "a point in space", but it is more like a small bump in space. This was made from a some of the two 19mm plywood pieces I glued together to make the other stop block and spacer. It uses the same T-track hardware as the blocks, but the M6 screw is shorter and buried about 15mm into the block, just in case I misjudge horribly and run the block through the saw. The block extends 30mm from the fence surface, so when I cut using it, I add 30mm to the LS-25 tape to account for the offset.

    This is the setup I used to cut the 61.5mm wide HDPE strips from the 5mm thick sheet. This is also something I don't think I will ever do again. The saw didn't have any problems with the material, but the dust collection was useless, and the static cling for the little bits made it stick everywhere. I spent about an hour vacuuming up the shop and the inside of the saw.


  9. #9
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    Quote Originally Posted by Jim Becker View Post
    Steve, if one doesn't have the small miter fence mounted all the time like I do, removing that entire aux table only takes a few seconds.
    I don't leave the small miter fence mounted all the time because it makes it that much tighter in my basement shop. That being said, my miter fence is actually positioned just a hair in front of the auxiliary table, so in theory I could remove the aux table even if the fence was installed.

    However the aux table on the Hammer seems to be a slightly different beast than that on the Minimax. Oh, it has the same 3 concepts: A set of adjustments for height, a set of adjustments for angle / level, and a set of securing bolts. But they're all just finicky on this table. The securing bolts are socket cap style, so I would have to find that Allen key. And you're not supposed to remove them entirely: instead, the side of the table has keyhole-style slots so that you can remove it by just loosening those bolts and lifting the table straight up and then out. But I remember having such a hard time getting this thing aligned the first time that I don't want to mess with it.

    Eh, maybe some day I'll try removing it and reinstalling to see if it will go back exactly where it belongs. If so, then I would consider buying a second table for mounting the LS Positioner.
    And there was trouble, taking place...

  10. #10
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    I use the small miter fence constantly, Steve, but I am a little less space constrained than you are. Since I cut down the right side table, I leave the full outrigger on, too.

    I'm sure there are a few differences between the SCM/Minimax and Hammer/Felder designs for accessories. I don't know what you have for those setups, but the OEM attachments that go on the side of the wagon for SMC/Minimax, there are two hard blocks that ride in the slots, so once the height and level are dead on with the wagon top, putting them on and off requires zero adjustments other than cranking down the knobs to secure them. The setup that Mike shows up above certainly benefits from that because any induce angle between the wagon and table surface can affect the measurement of the guide to the blade, albeit it will be small.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  11. #11
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    Mike — Great thread. I’ve seen Sam’s videos as well and it looks like a really nice and versatile set-up. After you use it for a while, let us know how it compares/contrasts with the Fritz and Frantz approach most of us “slider-heads” use.
    There is a very fine line between “hobby” and “mental illness.” - Dave Barry

  12. #12
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    Very impressive! Makes a good saw even better!

  13. #13
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    Quote Originally Posted by Jim Becker View Post
    I use the small miter fence constantly, Steve, but I am a little less space constrained than you are. Since I cut down the right side table, I leave the full outrigger on, too.

    I'm sure there are a few differences between the SCM/Minimax and Hammer/Felder designs for accessories. I don't know what you have for those setups, but the OEM attachments that go on the side of the wagon for SMC/Minimax, there are two hard blocks that ride in the slots, so once the height and level are dead on with the wagon top, putting them on and off requires zero adjustments other than cranking down the knobs to secure them. The setup that Mike shows up above certainly benefits from that because any induce angle between the wagon and table surface can affect the measurement of the guide to the blade, albeit it will be small.
    I'm gonna semi-hijack this thread from last week to show what the connection looks like for the auxiliary table on my Hammer K3. Sorry for the slightly out-of-focus picture.

    Those two larger socket cap bolts are what secure the table to the wagon. As you can see they have keyhole-style slots below them, so in theory you just loosen those bolts and lift up the table, leaving the bolts hanging on the edge of the wagon. There are mating blocks in the T-slot, as you would expect. There are a couple of annoyances to deal with here however. The first is that you basically have to loosen those bolts nearly all the way to remove the table, due to the depth of the height adjustment pins. Multiple times while messing with this I ended up accidentally removing the bolts from their mating blocks entirely. Also, those blocks in the T-slot aren't "full depth", so as you go to remove the table the bolts move around and get caught in the keyhole slots.

    The next set of bolts just to the left and right are the ones that control the height of the table. These are really poorly designed. That's not a lock nut you see here; that's just a washer and a regular nut. And that black screw they're holding is NOT a socket cap style. It would make sense if you could put an Allen key into it from this side and then tighten the nut, but that's not the design. Nope, instead the Allen key goes on the other side... hidden within the T-slot! So even if you line up the table completely flat with the wagon and then go to tighten these nuts for future repeatability, they might not tighten because there's nothing preventing the bolt from rotating. Yeah, you could try to put a star-style lock washer on the other side, but that washer would have to be smaller than the already small head on those bolts, otherwise the washer would be up against the edge of the T-slot. Note that the equivalent adjustment pins on the outrigger are not this style; they are much bigger, and have both the Allen key and the nut on the same side. I have no idea why they didn't do an equivalent design here.

    Those lower bolts with lock nuts in the far corners are what adjust the angle of the table relative to the wagon. They work just as you would expect, and I have no complaints about them. lol Well, okay, you have to be careful not to move the head when tightening the lock nut, but that's typical for this design.

    k3 table.jpg

    So against my better judgment the other day I removed this table (after attempting to tighten those alignment pins). When I put it back on it was way out of alignment. So then I spent about 20 minutes trying to realign it before giving up. I went back the next day and got it aligned, and I think those alignment pins are tight now. But right now I'm leaving it as is and don't plan on removing it anytime soon. Ugh.
    And there was trouble, taking place...

  14. #14
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    Thanks for posting that, Steve. It's helpful to understand the situation and isn't really off-topic because the idea that the OP posts about is usable regardless of slider brand. On the SCM/Minimax sliders, these accessories attach with those spring-loaded knobs that you can turn in close quarters and the accessory is held in alignment by some captive composite blocks that engage with the tee-slot on the front face of the wagon. I think I'd share your frustration with having to make alignment adjustments every time a support or measuring accessory has to get moved to a different position on the wagon...different cuts often require different setups. Next time you visit, I'll try to remember to show you how my machine is configured...perhaps you can then make some changes to your auxiliary table fastening setup to make it more easily moveable.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  15. #15
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    Quote Originally Posted by Jim Becker View Post
    Thanks for posting that, Steve. It's helpful to understand the situation and isn't really off-topic because the idea that the OP posts about is usable regardless of slider brand. On the SCM/Minimax sliders, these accessories attach with those spring-loaded knobs that you can turn in close quarters and the accessory is held in alignment by some captive composite blocks that engage with the tee-slot on the front face of the wagon. I think I'd share your frustration with having to make alignment adjustments every time a support or measuring accessory has to get moved to a different position on the wagon...different cuts often require different setups. Next time you visit, I'll try to remember to show you how my machine is configured...perhaps you can then make some changes to your auxiliary table fastening setup to make it more easily moveable.
    Before I got the saw I read a few comments here and there about people having trouble with this auxiliary table and that they simply don't move it or remove it after getting it setup the first time. I know Marius Hornberger of YouTube fame has the small K3 and hangs his table up when not in use, but I've never seen a video of him dealing with installing or removing the table.

    At the very minimum, I would like to be able to replace the position adjusting bolts with ones that are smooth on the wagon side and threaded on the table side, but with a hex head embedded in the end of that threaded side, similar to how the outrigger is done. That would allow for better setup. And of course some way to make the actual securing bolts stay completely horizontal when not in use. I can probably rig that up with just a piece of wood in the T-slot with threaded openings, assuming I have the proper tap on hand. In the meantime though, I'm just leaving the table where it is. lol
    And there was trouble, taking place...

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