Large Sebenza/Insingo FULL BACK SPACERS...

Made several test machinings this weekend with tweaks to the code each iteration. I'm now at a point where this morning I machined my prototype example in scrap black G10. Once off the CNC I fully assembled the knife checking fitment, kerf clearance and overall appearance. All looks good...!

Next is the machining of a proofing spacer in black canvas Micarta using the squared 'V' scallop profile.

Here's a few photos of the black G10 prototype...

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Moving forward from testing with black scrap G10 to proofing with black canvas Micarta... the back spacer fits perfectly. I ran off a short run of four... put one in my Sebenza but what I finally noticed and what I didn't think all the way through was that with the machined nub approach the back spacer material... Micarta or carbon fiber... is visible when looking into the lanyard holes. This may not be acceptable to CRK purists and I personally don't care for it either.

On the Small 21 I used the stepped lanyard pin to fix the rotation of the back spacer around the stock metal spacer. With this Large back spacer I designed a machined indexing nub that uses the knife's lanyard hole in the presentation scale to prevent rotation. I thought this approach had solved the issue of rotation since the Large has a non shouldered or straight lanyard pin which cannot be used.

So... seeking another solution I thought it might be possible to use a Large Sebenza 21 body pin and body screw in the lanyard hole. This in effect would take the place of the lanyard pin and I could use the same method as I used with the Small 21... but it appears the lanyard hole is not chamfered as deeply as the body holes and the CRK hardware would sit proud of the scale surface.

This may not be solvable... but I did locate a Titanium .187" plain button headed pivot assembly that I'm going to investigate as a solution. The ONLY issue is that it is TORX rather than HEX. That introduces an appearance discordance.

I'm thinking to possibly flame color this Ti hardware and try to get it into the blue spectrum to match the thumb stud and lanyard pin hue. Pricey little suckers and the standard $8.95 shipping charges from TiConnector sucks... we shall see...
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Pondering on this appearance issue where peering down the lanyard holes and seeing the black canvas OR carbon fiber (when and if I get that far) of the back spacer... I think it might be prudent to get the three Micarta back spacers left out of the short run I machined into some other knives. Get some feedback on whether seeing the material surface at the bottom of the hole is acceptable or not.

So... I'll place the three I have on the Knife EXCHANGE in Gadgets & Gear (Individual) at a discount. 100% money back if you are not satisfied... I would just ask for feedback.


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Nice work. I have one made for another maker for Sypderco military, and god know I need some for my Benzas too:D
 
BOOMER52 said:
Pondering on this appearance issue where peering down the lanyard holes and seeing the black canvas OR carbon fiber (when and if I get that far) of the back spacer... I think it might be prudent to get the three Micarta back spacers left out of the short run I machined into some other knives. Get some feedback on whether seeing the material surface at the bottom of the hole is acceptable or not.

So... I'll place the three I have on the Knife EXCHANGE in Gadgets & Gear (Individual) at a discount. 100% money back if you are not satisfied... I would just ask for feedback.


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I’m not sure how much I like seeing the micarta through the lanyard hole. What if you designed it to work with the MXG Gear shouldered lanyard pin for large Sebenzas then sold them together as a kit? Then it would work like the small Sebenza. Just a thought.
 
I'm not plugged into the CRK world sufficiently and didn't realize there existed a stepped or shouldered lanyard pin for large Sebenzas...! I will absolutely investigate this and at first blush it seems to be THE solution to the dilemma for the rotation fixation in the large that caused me to abandon the large spacer development.

Thanks for the suggestion and info...!
Steve
 
When I couldn't elegantly resolve the issue with the lack of a stepped or shouldered lanyard pin with the Large 21... I abandoned the project.

Photoman12001 informed me of the MXG Gear shouldered lanyard pin for large Sebenzas and this pin could resolve the issue I was unable to machine my way around. I would like to give the Large back spacer another try incorporating the MXG Gear shouldered pin. Since I sold the Large 21 PJ... I no longer have a knife for development.

If a forum member was willing to loan me a Large 21 to complete development of the back spacer... I would send the knife back with a carbon fiber back spacer and MXG Gear lanyard pin installed. Preferably an Insingo... because of the blade shape... if it works for the Insingo... the drop point will also fit.

My books are closed presently... so I have the time to devote. I'm uncertain just how long I might require the loan of the knife... but I still have the CAD/CAM files from the first attempt... so it should be a fairly short process.

Steve

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I'm going to revive this thread and again attempt to find someone with a Large 21 willing to loan me their knife to finish the development of the full back spacer using an MXG Gear shoulderd lanyard pin. The offer I made above still stands.

Down the road a bit I will acquire a mini 7X lathe and turn my own Ti pins.
 
Several very generous Forums members have offered to loan me there Large 21's and I thank those for the offers.

A Large 21 Insingo will be coming my way shortly. I've ordered the MXG Gear Ti shouldered lanyard pin and a sheet of 1X1 checkerboard LVA carbon fiber to hopefully coincide the deliveries with the knife so I can dig in immediately on finalizing this back spacer development.

I'll post up the progress as it happens...
 
The loaner Large 21 arrived and since I'm picking up where I left off with the failed inclusive machined fixation stub pin... it was a simple matter to modify the CAM file to machine a hole where the stub pin was previously. This hole will accommodate the stepped or shouldered titanium lanyard pin from MXG Gear.

Using some scrap jade G10 I already have the test profile locked down. The fit is perfect and the clearances appear appropriate...

I'll be moving up to full thickness with the next machining using some scrap G10 for this shouldered pin prototype back spacer.

I would like to thank Forum brother photoman12001 for his suggestion to use the MXG Gear lanyard pin... I was unaware of its existence.

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Looks amazing!!! Can’t wait!!! Will you supply the stop pin or should I just play my lucky hand and order one just in case?
 
At this point in time the stepped lanyard pin will NOT be included. It will need to be separately purchased from MXG Gear. Down the road a bit I will hopefully be acquiring a 7X mini lathe to machine my own Ti pins.

I machined the prototype spacer from some scrap black G10 and everything looks good. I did end up widening the gap at the very tail of the back spacer to increase the clearance at the very tip of the blade.

Now... I need to create a jig that will allow me to machine the linear kerf or slot for the blade edge clearance with the blade in the closed position.

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OK... got a bit of free time and managed to machine out the first carbon fiber version of the Large 21 back spacer.

It's fits perfectly to the frame.

It still lacks the secondary machining of the blade clearancing kerf or slot. That's up next. That operation requires a custom jig to clamp the back spacer in a vertical position (belly up if you will).

Progressing nicely...

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With this back spacer having the need to use the lanyard pin as rotational fixation... one loses the ability for a lanyard.

For some that will not be an issue... however for those where a lanyard is still desirable does the back spacer design as seen below satisfy the function and CRK aesthetics...?

It could be done with CF... but I question whether Micarta would be strong enough as currently designed.

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