Sewing collars & leashes with an LK-1900BN bartacking machine

You'll have to remove these screws to change the "work clamp feet." These are notoriously difficult to loosen. It has something to do with their anodized finish (binding with the anodized finish of the plate, the beveled mating surface). When they snap free, they spin so freely you'll think you snapped the head off.

Usually people heat over-tight screws. But, putting the arch in the freezer works much better for these. Leave it for hours (let it completely freeze to its core).

I bought additional arches, so I got more experience with this topic than you normally would. I spray some "Liquid Wrench" on the screws, then heat it with a heat gun. When cool, I put the arch in the freezer. The expansion before contraction of freezing may help. But, I wouldn't try to loosen while it's hot. It always snaps free easier when frozen. (If you try when it's hot, you're just risking rounding off the head in a way you wouldn't if you wait till it's frozen.). After a deep freeze, if the screws don't break free, I do it again (penetrating oil, heat, deep freeze for hours). I think it helps to strike the screwdriver with a hammer when frozen. (It may help when hot too. But trying to loosen when hot doesn't work as well as when frozen. I would only try to turn the screw when frozen. The odds of it breaking loose are much greater. Therefore, you're just increasing your risk of rounding off the head if you try to turn it when hot.). Cycling through hot/cold helps more than striking the screw (if you're not comfortable striking it).

You need a vice to do the above. Clamp it between some wood so you don't mar the arch. It's a good idea to buy a few spare screws (#SS2110930SP, desc: SCREW 11/64-40 L=8.7). You might partially round a slot. But, if the seller breaks these free for you, you'll have less potential need for spares.

These seem to be hard to turn due to thread-locking compound. Heat works better than freezing. What makes these risky is that they're tiny. You need a jeweler screwdriver (which aren't made for this kind of duty, they can snap if you turn too hard). Also, if you round the head off, it would be harder to fix because of the screw's size & being recessed.

To get enough torque, I clamped long-nose clamping pliers onto the screwdriver. With my thumb pushing hard against the end of the screwdriver, I rock the screwdriver with my other hand (using the clamp for grip). I rock back/forth very little and the screw will begin to give. (Trying to move it too much will break the tiny screwdriver). Cycling cold/hot might help. But, I wouldn't try to turn it while frozen. Heat & penetrating oil, rocking it back/forth is when there's more chance it will loosen. The key is to rock it back/forth. You might have to do that until it's all the way out (it can take a lot of time).

(Spares: #SS8080310TP, desc: SCREW 1/8-44 L=2.8)

This one's not as bad as the prior two. It may need some penetrating oil & heat. (If that doesn't work, try it again after freezing).

The "ball retainer" actually retains a flat slider part. Prior versions of the 1900 used balls. The parts manual still refers to the retainer as if balls are still used (but it's not the same part #). You may need to adjust the retainer up/down. If too low the front of the arch will flex up/down too much. Too high you could get an E926 error when the machine initializes (the arch won't move freely enough).

(Spares: #SS8150510TP, desc: SCREW 15/64-28 L=4.7. I don't think you need a spare for that setscrew. But, I think it's easy to lose the "slider" #40142736 if you remove the arch. A spare might be handy to have.)

These screws are almost as difficult as the 5 faceplate screws above. Once again, it seems like it's the anodized surfaces under the screw head that binds to the anodized surface of the lifting levers. These break free easier when frozen (follow the advice for the faceplate screws).

These let you adjust the height of the "work clamp feet." This is mainly to make them level. But, you can adjust both sides 3/8" higher/lower.

(Spares: #SS7110740TP, desc: SCREW 11/64-40 L=7)

The reason I suggest pre-loosening these screws is because they're hard to access (with the machine's head above). Trying to turn them with a long screwdriver at an angle could round the slot. Using a shorter screwdriver could be awkward to hold & push down while turning. If you round one of these off, it would be hard to fix due to the lack of access.

The needle plate is more common to remove. You have to remove this to access the cutting knife (27) underneath. I had to remove it to replace the hook & shuttle driver (when upgrading to the high-capacity bobbin).

(Spares: #SM1040650TP, desc: SCREW M4 L=6)

You'll have less reason to remove the presser plate. But, like the needle-plate screws: if you round one off a head, there's no access to drill it out. (They need to be tight or they'll vibrate loose. But, they may come from the factory excessively tight.)

One risk which may necessitate removing this plate: when you remove the arch, the "slider" (in the "ball retainer" cup above) may stick to the "slider sheet" above it (due to the grease on the sheet). I always worry it could fall off. If the "feed plate" (29) were removed, the slider could fall inside.

(Spares: SM1040650TP, desc: SCREW M4 L=6. Same as used for the needle plate.)

Note: the "feed plate" (29) screw was also stubborn like the face & lever-plate screws (it snaps free. The anodized finish between the screw head and washer binds like those screws.). Grease between the screw's head & washer helps. Eventually the anodized finish wears off enough that it stops doing it. (FYI: That screw has a 4mm allen-head which reduces the risk of rounding off. However, I felt like I got a slightly better fit using a 5/32" allen wrench.). You can buy allen wrenches with a ball-shape on the long end. Those are handy to quickly snug the plate (and the 5mm arch screw). Then use the short end (which shouldn't be ball-shaped) to fully tighten it.

The machine uses 135x17 needles (also called DPx17). I use size 140/22 for all the webbing (both Tex-70 and -90 thread. Usually you'd use a larger needle with heavier thread.). It wouldn't hurt to have smaller 120/19, 130/21 & larger 160/23 needles. Ask the seller of the machine what would make sense to experiment with.

I use Groz-Beckert 768692 RG point (round with small ball point) SAN5 (which means improved thread guidance), "gedebur" (means titanium coated).

I started with Groz-Beckert 761032 R point (regular round point). They worked ok. The seller suggested SAN5 might work better. I think it does. When I switched to those, it seemed like the thread-tension balance (between needle and bobbin threads) was more consistent, less touchy. SAN5 has a larger channel for the thread. That might be why (the material isn't affecting the needle tension as much?).

You'll want more lighting than the machine's built-in light. You can buy gooseneck lamps that clamp onto the table, or you drill a hole & install permanently. There is a common design used with industrial machines (google industrial sewing machine lamps. You'll see lots of these). They seem to be called SNU-21, or SNU-26 referring to the length of the gooseneck. The -21 has a larger hood (6-1/2" long, 4" inside diameter at the opening) for use with an A21-size bulb. (Being shorter length, it can hold more weight? The SNU-26 has a smaller hood - 5-3/4" long, 3-3/4" ID - for use with a smaller A19 bulb.). Note: You'd only use a 40- or 60-watt (equiv) bulb in either fixture. Those brightness levels are available in either bulb size. But, if you use the larger A21 bulb in the SNU-26's smaller hood, it will protrude & be glaring to the eyes.

I installed a SNU-21 lamp each side of the machine:

The SNU-21 barely reaches on the left. The longer -26 might be a better choice. (Not just for the length, but the hood is a little smaller. The -21's hood feels a little in the way. If I did this again, I would start with -26 on both sides. The bulbs would be the same 40W-equiv brightness, just the smaller A-19 in a smaller hood. I think smaller hoods would fit better. But, it's important not to use the same A-21 bulb. It will protrude a little. To the extent you can see that protrusion, it will be glaring.).

It's important to note that the machine may have to lay on its left side for service someday (warning: requires two people to safely tilt over). That lamp should be installed so it doesn't interfere with that. I.e, my table is only 36" wide. If the machine head tilted over, it would extend to the left edge of the table. I can' mount a lamp on that edge (except perhaps at the rear corner). For me, mounting the light directly behind the machine worked well. The light can bend straight up to allow the machine to lay on its side.

The machine comes with a built-in light with four brightness levels. It seems glaring to me. Putting some scotch tape over it might help (or tape some tissue paper over it).

The control panel has many options (called "switches") accessed by the "M" button. Press it once (one beep) and that's the options for normal operation. Hold it 2 seconds longer and you'll hear a 2nd beep. That gives you access to additional options. Hold it another 2 seconds for a 3rd beep gives more options. These options are listed in the instruction & engineer manuals. It helps to see them at a glance that way before seeing them on the control panel. (Juki's manuals are hard to understand. It doesn't help much.).

Don't play with these options (too soon, too many at once). Be sure to write down the value it was before changing so you can get back to where you were. There's probably a "factory reset" but I haven't had a reason to look for it yet. If you write everything down you shouldn't have to either.

It's easy to accidentally press the +/- keys intending to press the up/down arrow keys (to the prev/next "switch"), changing the value of the item you're still sitting on. If you think you've done that, power off (I don't think it saves until you press the return "↩" button. By "power off" I mean the power switch mounted to the table, not the green ready button on the control panel.).

When I had trouble winding, I considered using a standalone winder which works with these bobbins (style A, class 15?). This is the only one I could find:

I don't recommend it, but thought I'd include the info here. That photo comes from Amazon (ASIN: B07RJL9XHY seller CKPSMS). You'll find many sellers of this winder. I chose that seller because their photos were more informative (instructional. The english is hard to understand. But, that was more than other sellers do.).

It works. It could be worth having on hand. But, lots of caveats:

1. Most of the spools I use won't fit its stand. You need a standalone thread stand. I have one with a cast-iron base (Amazon ASIN: B01ELYA1HC). That same stand is also sold with a plastic base. The cast-iron base is worth getting. I cut a piece of felt to fit the bottom, and glued it on.
2. Insert the thread into the guide hole, then go 3/4 turn around the tension disk, then straight to the bobbin. (You might be tempted to go all the way around to the guide hole, and exit that hole the same way you use the LK-1900's tension disk. But the guide isn't positioned properly for that.).
3. The shutoff sensor is light-based. If you have too much light shining on this, it won't shutoff. You can easily improve this by taping some cardboard around the sides/end. Add a horizontal piece to the top of that shade.
4. The tension disk is problematic in a few ways:
   • It's too close to the bobbin. You'll center the vertical height of the tension disk so the thread winds evenly up/down the bobbin. But, being so close it won't let the thread travel that far up/down. You'll end up with a bulge in the center of the bobbin. You can sew with it. But, you're not using the entire bobbin's capacity.
   • The silver knob adjusts the height of the tension disks, but it also limits how high the beige knob (tension adjustment) can go. This is more of a problem the lower the tension disks need to be. The lower the tension disks are (for a narrower bobbin), the stronger the tension on the thread. Even with the taller LK-1900 bobbins, I felt like the tension is too much. (This could also contribute to the thread not fully traveling up/down the bobbin).
   • The guide hole isn't positioned to let you go in and out of it the way they usually work.

If I were going to use this winder, I would, make some improvements:

1. Mount the box to a plank of wood (not the small steel plate it comes with).
2. Make another box (or stack of wood, something the same height as the winding box) to mount the tension disks to. Mount this on the plank of wood so the tension disks are twice as far away. Also, orient the guide hole so you can go in & out of it using an external thread stand.
3. Replace the tension disk with the one used on the LK-1900 (#141-13468). It's not very expensive, but much better quality. (Or, I would replace the silver center knob with some threaded rod so the beige knob can adjust higher, allowing the tension to be reduced more. I would take the silver knob to Ace Hardware and find something with the same thread, but longer.).
4. Add some shade around the sensor end.

I think it would be a good winder with those changes.

The control panel has a function to wind the bobbin (while not sewing) (instruction manual pg 23). But, the entire machine operates. That's a lot of wear & tear. I've done it when I had to, but wouldn't do this as the normal way to wind bobbins.

If you have to use this feature, be sure to unthread the machine past the takeup lever. If you don't, the thread can be pulled into the machine at the lever. That could take a lot of work to fix (removing the front & top covers of the machine, etc.).

I would use the standalone winder before doing this.

I bought a case on e-Bay that looks like this:

Notice how one of the guides (which the thread's supposed to stay between) hangs off the side of the case. The thread easily pulls past that guide, feeding from behind it - coming off the side of the tension plate. It wasn't a big problem. But, it's hard to get the thread tension balanced. You can find the other style (shown above, both "guides" go down into the square hole in front). This onw may be an older design.

This one might work better with tex-90 (thicker) thread. Maybe that wouldn't slip past the guide as easily. My experience could also be due to me adjusting the bobbin thread tension to be pretty light. That means the tension plate is sprung higher, and the guide doesn't hang down the side of the case as far. Maybe that side of the tension plate could be removed & bent down a little to make that guide fit better. (FYI: I used light tension because whenever I made a mistake - like forgetting to install the d-ring before sewing the buckle-end - it was a lot of work to fix if the stitching was tighter. Having light thread-tension makes it easier to use a thread-ripping tool to "unsew" the mistake. I made a lot of mistakes in the beginning. This saved me a lot of time. But, couldn've contributed to this bobbin case not working as well.).

The inexpensive clamps I bought needed a little filing/polishing to fit into the arch's slots & slide freely. You'll need a polishing stone. I used a Harbor Freight Gordon Combination Sharpening Stone. It has a rough & fine surface. Be careful not to go too far, and make it fit too loose.

The clamps also tended to come down "toe-up" (the heel down more. That allowed some movement as the plate/clamp moved.). I placed mine in a vice (with a piece of wood protecting the polished surface from the vice's surface) and tapped them lightly with a hammer to align them a little better. Take your time, go slow. I tapped one clamp so far back (to bring the toe down enough to be flat) that the feed plate wouldn't go back far enough (it hit the arch's base). I had to grind some material off the end of the plate so it would move further back toward the arch's base. Be prepared. (Tapping the "thigh" of the clamp down won't move the foot back as much as tapping on the "shin.").

If the height of the two feet aren't the same, you can adjust the "lever driving plate:"

Those are the screws I suggested having the seller loosen for you. Be aware: There is a real clamp-height adjustment under the machine's top cover (instruction manual pg 51). You shouldn't ever have to do that. These plates give you some overall height adjustment. You can use a dremel to elongate the holes even more than they are (for more adjustment).

As mentioned above (work clamps & feed plates), you can use the factory 27mm clamp for everything. But, if you buy clamps to better fit the different collar sizes (box-x clamps are almost necessary for the thinner leash webbing), you'll have to change the clamps. That isn't as easy as it could be. Your choices:

This topic applies the most to the 1-1/2" collar due to its weight. What I found is that pinning the webbing against the feedplate screw solves the problem. (I provide more info about this technique in the footnote to clamping onto the tri-glide.). It makes the webbing solidly part of the moving feedplate & arch. I don't have to do it with everything. It helps with the larger collars.

For the smaller collars, I might push down on the plate (not the screw). They don't need as much help (they don't vibrate as much). Or, I might suspend the webbing lightly in my hand, trying not to add any tension or weight to what's under the clamp.

The last tack requires the webbing point towards you. Just lightly suspend that, giving it a lot of slack so the clamp can move around without the material resisting. You can do the same thing when the material points to the rear. But, for some things it works better to hold it down tight on the plate - and even better against the screw.).

When sewing the buckle end, it's possible to clamp too high up against the buckle (or the D-ring). When sewing starts, it will slip down (revealing the the straight basting stiches outside the zig-zag). Wag the webbing side-to-side a little to let the clamp settle if it needs to.

That last point (about clamping too close to the buckle or ring) caused me to grind some of the front off the 3/4" clamp (shown below) so I can clamp closer to the buckle & ring. I'm tempted to do that with this 1-1/2" clamp (and 1" too). It could be better. The clamps I bought were inexpensive. It wouldn't be risky to try. (I wouldn't do this with the 1" clamp the machine comes with. Original Juki parts are expensive. I'd buy an aftermarket 1" clamp to experiment with.).

I sew just one bartack at the -Short's tri-glide. I increase the zig-zag height (y-scale). (See the table of pattern settings). Enlarging the zig-zag seems like a good idea (to use more of that space). But, don't forget that it could cause the needle to strike the feedplate. Be sure to double-check how the pattern fits the feedplate. (If you clamp onto the tri-glide the way I do: a larger zig-zag increases the chance of the needle striking the tri-glide. Also, more travel can mean more vibration - which increases the risk of the tri-glide moving under the clamp. It can slip & be struck by the needle. Or, the foot can slip entirely off the tri-glide.).

The -Long collar has two bartacks each side of the ring (like the larger collars):

I use the lowest zig-zag (y-scale) for those. See the table of pattern settings.

The -Short collar uses just one bartack each side of the ring (at the buckle first, then the tail):

Like the single-tack tri-glide: I increase the zig-zag (y-scale) of this single-tack too, but not as much. See the table of pattern settings.

Notice that I use a smaller clip to hold the tail (when sewing the first tack at the buckle). That's a very tight fit to get an ordinary plastic sewing clip into that space behind the work clamp. These clips are called "Mini Alligator Clips" (I bought Amazon ASIN: B0F2T9YJH6.). The ones I bought have a silicon mouth (insert) inside the metal clamp. Some of the other sellers seemed to show a photo of a clamp without that insert. I think the silicon grips better. (These might even work better than the common plastic clips. Those clips stress from repeated use, and break after some use. They're cheap; it doesn't matter.).

It's challenging to align & center this. First of all, you should draw Sharpie lines on the faceplate showing the edge of the cutout. When sewing, you have to pay attention to three things.

1) I clamp-down once (and release) to flatten the webbing. Then I move the webbing left/right. I look at the front mark, and position the webbing so the melted end extends far enough past the cutout:

2) I hold my head to the left side, and move the webbing front/back. I look at the side marks, and position the webbing between those:

3) Make sure the two layers of webbing are stacked squarely (the melted end doesn't overhang one or other side). Pulling it tight helps align the layers. But, then you have to do #1 & 2 again.

This goes slower than collars (but, you only sew twice. You sew the collars six times.). Take your time. Double check. This would benefit from guides attached to the feedplate.

The control panel (where you set the speed, x-/y-scale, etc) allows you to adjust the x/y position. I adjust the y-offset a lot. When I position the webbing (per above), even though it looks centered to me (front/back), the box comes out uncentered. You can either make a mental correction to your positioning, or change the y-offset so it comes out as you think it should. (I go back forth between mental and offset. The risk of doing that is: you might chase it around if you don't settle on one way of looking at it, doing it.).