Large Sebenza/Insingo FULL BACK SPACERS...

That is a generous offer... very much appreciated and I thank you... but I must decline.

I will only use a knife I own for my development work...
 
Got word from Lady1911, the small titanium spacers fit on both 21 and 31.

Not to say the large will as well, but I think it's safe to assume zero issues there.
 
I have a Large 21 Sebenza, an Inkosi AND an Umnumzaan inbound for full back spacer development.

I already have the Large 21 full back spacer coded up but I made a switch from the MXG Gear lanyard pin to the less costly CRK stepped lanyard pin and I need to nail the barrel circumference diameter and plug that into my machine code. A batch of back spacers for the Large 21 should follow in the near future.

With regards to the Inkosi... I had a request to determine IF it was a possible to engineer a full back spacer considering the Inkosi does not employ a dedicated lanyard pin... instead using the heel standoff to fix the lanyard. I conferred with fellow member TTTis (Titanium back spacer wizard...!) and we agree there is a potential solution that I'll be working on as soon as the knife arrives. A big IF is hidden in that statement.

The Umnumzaan will also get worked up and hopefully I can design a full back spacer for it.

Lots to do but it's with the hope these efforts will result in more back spacer offerings for a wider number of CRK knives.
 
Very excited to see the next installment, the progression has been awesome. If this tweak does work, I may have to modify the small seb spacer design for the next run. I really hope it does work as it will make a very solid spacer!
 
I received my Umnumzaan the other day and I worked it up in CAD today.

There is NO hard rest for the front end of the back spacer... however the Umnum has a stepped lanyard pin the will provide the anti-rotation fixation. I do believe that carbon fiber and G10 have more than sufficient stiffness for the cantilever.

A smooth prototype as seen in the render will be machined and I'll post up the results!

ryWHzeP.png
 
I received my Umnumzaan the other day and I worked it up in CAD today.

There is NO hard rest for the front end of the back spacer... however the Umnum has a stepped lanyard pin the will provide the anti-rotation fixation. I do believe that carbon fiber and G10 have more than sufficient stiffness for the cantilever.

A smooth prototype as seen in the render will be machined and I'll post up the results!

ryWHzeP.png
Question? Will the glass breaker clean the topside of the backspacer as seen in the renderings? The umnumzaan is my favorite of the CRK's and its gonna be a must have for me. Along with one for my customized large 21 insingo. Solid work brother.
 
The back spacer will be proud of the spine and heel. I don't have the actual dimension as yet... the stiffness of the cantilever will dictate that final dimension.

I wouldn't consider CF or G10 material as a capable glass breaker. I suppose it's possible with sufficient force...
 
I filled the spine gap to maintain a clean line... however the blade heel tang will require a relief kerf... OR I shorten the spacer slightly.

I'll work with the kerf in my first prototypes.
cDnUYRc.png

tQUYrZH.png
 
I filled the spine gap to maintain a clean line... however the blade heel tang will require a relief kerf... OR I shorten the spacer slightly.

I'll work with the kerf in my first prototypes.
cDnUYRc.png

tQUYrZH.png
Thanks for the reply. The umnumzaan is the only (to my knowledge) CRK to have a glass breaker on it and was just curious to the clearance. Cheers.
 
Would the glass breaker be the blade heel tang that projects beyond the scale profile at the pivot end with the blade closed...?

That's the ONLY reason I can come up with for that sharp tang to be present...
 
Would the glass breaker be the blade heel tang that projects beyond the scale profile at the pivot end with the blade closed...?

That's the ONLY reason I can come up with for that sharp tang to be present...

Yes. CRK advertises that the “point” on the blade heel tang is a glass breaker.
 
The Inkosi has arrived and shoehorning a back spacer in this one is 50/50 at this point. I have scanned the parts and the tolerances are UBER tight as you'd expect with anything CRK.

I have it in CAD now and the critical issue will be the lower jaw hook at the frt of the back spacer. It has to do with the full blade thickness at the closed blade stop cusp. I will need to keep as much material as I can at the jaw hook which must capture a sufficient degrees of the blade stop circumference to fix placement and prevent the back spacer from rotating around the heel standoff.

It's going to be critical that the jaw hook has the required stiffness once the clearance kerf is machined to accommodate the sharpening choil region.
0HRKMc7.png
 
The Inkosi has arrived and shoehorning a back spacer in this one is 50/50 at this point. I have scanned the parts and the tolerances are UBER tight as you'd expect with anything CRK.

I have it in CAD now and the critical issue will be the lower jaw hook at the frt of the back spacer. It has to do with the full blade thickness at the closed blade stop cusp. I will need to keep as much material as I can at the jaw hook which must capture a sufficient degrees of the blade stop circumference to fix placement and prevent the back spacer from rotating around the heel standoff.

It's going to be critical that the jaw hook has the required stiffness once the clearance kerf is machined to accommodate the sharpening choil region.
0HRKMc7.png
Would you be able to make white handles for the Emerson cqc 7??
 
OK... the first bit of work I've accomplished is to recode my large 21 back spacer to use the CRK stepped lanyard pin VS the more costly MXG Gear stepped lanyard pin. The center barrel diameter of the CRK pin was slightly smaller than the barrel diameter of the MXG Gear pin... so these new back spacers will from this point on exclusively require the use of CRK stepped lanyard pin.

I stopped machining Micarta a year or so ago due to a physical response I've developed to the fumes produced when Micarta is machined. I researched and purchased a 3M full face twin vapor cartridge respirator to test in the hope of alleviating my odor response so I would also be able to offer cotton canvas and linen Micarta in addition to CF and G10.

I managed to perform the respirator test this morning while machining a set of black cotton canvas Micarta cogged full back spacers. Things went swimmingly...! I'll have a batch of these large 21 back spacers to offer up in the near future once I complete some additional prototyping on new products. Not certain just when that may be however...

tYHijJe.jpg

5eiageP.jpg

DTd6TwB.jpg

US8QA5g.jpg

rNZfNcE.jpg

jWpFoLR.jpg

OeJ62SF.jpg
 
Getting back to the Inkosi... I nailed the design of the full back spacer on the first machining of the prototype. Fit perfectly! Machined it out of black G10 so it is plain... no frills... but it does look good as is! I can now add design elements such as gimping and cogging for future versions.

Now the caveat is that the machined sharpening choil region of the blade might slightly differ from blade to blade as CRK hand grinds/sharpens their blades. Hopefully the clearance slotting I have coded will accommodate those slight dimension differences with the hand grinding.

1rjgP6d.jpg

4aEBfpz.jpg

KsqYyMZ.jpg

VWHepNh.jpg

5pLVxa8.jpg

O6w6dOn.jpg

y2LsTjv.jpg

aZmch3o.jpg
 
Those are looking good is there any problem putting them on left headed knives?
 
Back
Top