Stitching through Kydex and leather with a Shapeoko CNC

[joshhartung]

Hi folks, I've been doing a lot of work getting my holster business up and running and thought I would start sharing some of the techniques I'm developing. I'm a mechanical engineer with a background in consumer product design. I've built and shipped hundreds of thousands of parts in my career and am trying to bring some of my knowledge of modern manufacturing to the fascinating world of leatherwork.

For my holsters I wanted to use a hybrid of Kydex and leather to get the good qualities of both. My holsters use leather to provide passive retention of your smartphone, which is awesome, but requires custom fitting to each case. The real challenge here is repeatability, where a difference of a single millimeter in sizing of the cavity can mean the difference between a loose and overly snug holster. The Kydex helps by being much stiffer than the leather without making something bulky or heavy.

But to use the hybrid approach, I needed to figure out how to sew them together. Soon I'll be moving up to a Cowboy 3200 compliments of Bob Kovar, but in the meantime I'm hand stitching by shooting a really consistent pattern through the two layers with my "power awl" (Shapeoko 3 CNC router). Works great, so I made a little video:

https://youtu.be/-AodfxfsNYU

[Joseph1836]

You have a website 

[shoepatcher]

beautiful.  makes hand sewing easier.  It will be hard-pressed to do as good with Cowboy 3200.

glenn

[Ed in Tx]

The hybrid holsters I have seen are normally joined using rivets not sewing. There isn't a sewing machine that I know of that would be capable of punching through kydex. Pre-drilling all of the holes might work for hand sewing but I would be very hesitant to attempt doing it with a sewing machine. The pre-punched holes would need to be oversized to accommodate the needle and thread. The type needle you use would also have a bearing on the hole size you drill as well. A spear point needle is different than a diamond point not to mention LL or LR twist types.

Just my 2 cents.. 

[supercub]

Several years ago I got an order for a hybrid kydex holster and mag pouch.  The customer wanted the kydex fronts stitched to a 10 oz. leather back.  I sewed them together with my Ferdco Pro 2000 (Juki 441) using 277 top thread and 207 bottom.  It worked just fine.  I did a minor adjustment to thread tension and the results were good. 

I didn't like working with kydex, so that was my only experience with it.  Sewing it was no problem with that machine.  Sorry, have no pictures of that project.  I would expect any of the comparable heavy stitchers would work as well.

[joshhartung]

Hi folks! Glad this has generated some interest.

@Joseph1836 I do have a website (though still kind of in startup phase so needs work): www.holstery.com

@Ed in Tx I was worried about stitching through Kydex as well, so before I bought the 3200 I sent a sample of 5-6oz veg-tan laminated to 0.093 Kydex T to Bob at Toledo sewing, who was able to get nice stitches through the material with a bit of tweaking. I'll post a video when I get this worked out, since the machine arrives tomorrow!

I did a lot of searching to find better ways to join the two materials, as I really don't like rivets. They're inherently a smaller footprint fastener, so they only actually connect the two materials at discrete points and the rest of the attachment is done by adhesive, which is prone to eventual failure. Sewing is much lower profile, meaning I don't need a big outside flange to attach the materials and the attachment is better with stitching because there are simply more attachment points. With stitching, the adhesive is there only to position the joint rather than provide any long-term holding.

[MY63]

I make a similar style of product although mine are for large fountain pens.

I had the same issue that you have at an early stage bringing the leather and kydex together my solution was to wrap the kydex in suede I was also concerned that contact with the Kydex could cause the tread to fray.

20180125_161847 by my0771, on Flickr

This is my formed Kydex

Trimmed

20180125_162630 by my0771, on Flickr

Then wrapped in suede.

IMG_20180125_163841_245 by my0771, on Flickr

Finally I add the outer cover and stitch through the leather front panel and the two pieces of suede and into the back panel which is also covered in suede with the kydex inside the edges .

IMG_20180125_223756_521 by my0771, on Flickr

I make these cases in various sizes.

20170927_091703[1] by my0771, on Flickr

I hope my experiences help you.

 

[joshhartung]

@MY63 cool technique, this looks very much like the Bianchi holsters used by police - Kydex is sandwiched in between other materials for strength and support. I like it!

[Mark842]

On 6/23/2018 at 4:06 PM, Ed in Tx said:

The hybrid holsters I have seen are normally joined using rivets not sewing. There isn't a sewing machine that I know of that would be capable of punching through kydex. Pre-drilling all of the holes might work for hand sewing but I would be very hesitant to attempt doing it with a sewing machine. The pre-punched holes would need to be oversized to accommodate the needle and thread. The type needle you use would also have a bearing on the hole size you drill as well. A spear point needle is different than a diamond point not to mention LL or LR twist types.

Just my 2 cents.. 

I sew through leather and Kydex all the time with a Cobra 4.

[joshhartung]

Confirmed, my 3200 sews through it like buttah.

https://www.instagram.com/p/Bk6FNLVDYtb

[wayner]

Cowboy Bob can you explain what tweeking you had to do to the Cowboy 3200 to get it to sew threw the .093 Kydex. I am very interested in hering about this 

[JLSleather]

On 7/5/2018 at 5:46 PM, Mark842 said:

I sew through leather and Kydex all the time with a Cobra 4.

Weird -- I would have thought it would crack.

[koreric75]

18 hours ago, wayner said:

Cowboy Bob can you explain what tweeking you had to do to the Cowboy 3200 to get it to sew threw the .093 Kydex. I am very interested in hering about this 

I didn't see a post from @CowboyBob about this, but @joshhartung had a.gif on Instagram showing it... I'm curious as well, and like @JLSleatheri would've thought the kydex would crack or split or the needles would be snapping points... Was this a leather needle or a sharp etc?... Inquiring minds want to know lol.

[Mark842]

3 hours ago, koreric75 said:

I didn't see a post from @CowboyBob about this, but @joshhartung had a.gif on Instagram showing it... I'm curious as well, and like @JLSleatheri would've thought the kydex would crack or split or the needles would be snapping points... Was this a leather needle or a sharp etc?... Inquiring minds want to know lol.

 

4 hours ago, JLSleather said:

Weird -- I would have thought it would crack.

Not the best pic's but here is a piece of scrap leather sewn to kydex. No cracking or splitting. Only issues you have to watch for is having to feed by hand as the feed dogs get no traction on the kydex. If your sewing a long run you have to sew slow or the heat building up on the needle will start to melt the kydex and raise the needle holes into little nubs or bumbs if that makes sense. I sew a ton of leather to kydex. I've never cracked kydex, or broke a needle or frayed thread or anything. Goes right threw like butter.

[CowboyBob]

They go though the leather & Kydex real easy.It just takes a little minor tension adjustment for the Cowboy CB3200 to sew Kydex.Here's a pic of  10mm or 13/32" of plywood ,slightly under 7/16" thick that one sewed.

[JLSleather]

12 hours ago, Mark842 said:

I sew a ton of leather to kydex. I've never cracked kydex, or broke a needle or frayed thread or anything. Goes right threw like butter.

Making what product?  I've never tried it, because I've not had CAUSE to try it.

 

[Mark842]

I use it on motorcycle bags so they hold their shape. Backing plates for windshield bags on Harley FLH model bikes and other stuff. probably abot 10-12 different products. Works great cause you can heat it up with a heat gun after stitching it in and shape it however you need.

[joshhartung]

Man, THIS is the forum post I needed when I was getting started. I'll note that I sew with a round point needle instead of a leather point, which I found would leave sharp "chips" attached to the Kydex side. I can confirm that the feed dogs don't get enough traction on Kydex, which is an important consideration - think about which side you will sew on BEFORE starting the project.

[JLSleather]

Now we just needa git Bob tell us what he's buildin' with that plywood 

[Wizcrafts]

When I got my CB4500 it included a set of feet with teeth on the bottom and a matching feed dog with teeth ("blanket set"). If your machine didn't come with these feet and feeder, contact Bob Kovar about purchasing them. They are listed in the pop-up accessories list for the Cowboy CB3200, 3500, 4500 and 5500. The serrated feed dog alone is listed at $50, plus postage. It would help eliminate slippage on Kydex.

[Ed in Tx]

I will admit it, I was very doubting about the ability of a sewing machine having the capability of sewing through kydex. Always wanting to see it before I believe it I tried it. Much to my surprise I was able to punch through the kydex with no issues whatsoever. I used a size 24 diamond point needle and 277 thread sewed together a 5 - 6oz piece of veg tan tooling leather and .06 kydex with no visible thread fraying.

I sewed it with a Cobra 4 machine.