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I've found that just hitting the SB-250 briefly (2-6 revolutions) with a cheap 120/180 grit diamond lapping plate works to redress the grinding surface. This technique also works really well with the SJ-250 though might take more revolutions on that.

Hello all,

We have 3 T-8s and sharpen thousands of knives a year. About a year ago we switched to SB-250s and generally love them. I'm noticing they constantly get out of true on all of our machines (so I don't think it's a problem with our machines), and I have to think we generally apply equal and random pressure as we sharpen - it's not like we press harder every revolution always in the same place. My only conclusion is that they wear unevenly for some reason.

Has anyone else noticed this problem? Every month or two I have to true them up to the tune on 2-4 mm and it feels extremely wasteful. I wonder if there is a manufacturing defect that is causing inconsistent wear. Would love to hear if other's are experiencing/noticing this problem.

Thanks!

I run a knife sharpening business and have developed and produced a retrofit for the KJ-45 to make it more like the SVM because adjusting the height of the bar is very cumbersome when you are doing a lot of knives. We set to 140mm projection and generally keep the height of the bar the same (cleavers are an exception). We micro-adjust on the fly to match bevel angles. We spend VERY little time on setup because of this. I keep thinking I should do a setup time race on 5 or 10 different size knives to show the difference, I'm sure it would be quite significant.

https://magnoliaknife.com/products/tormek-kj-45-adjustable-retrofit

Hi Ken, thanks for the questions.

We set to 140mm projection (sometimes we need to adjust to match specific bevels) but our default is 140mm to get a 20 degree bevel. The height of the USB changes occasionally as the wheel get's smaller - perhaps once a month. We now only need to change the USB for really, really wide knives like cleavers. The retrofit I've made seems to work for even the smallest blades @140mm. As the wheel gets smaller, we may need to go back to a two USB system for now we can leave it set at about 175mm for a 250mm wheel - it obviously changes as the wheel gets smaller. The smallest wheel we have currently is 225mm and it's still working.
I measure the wheels and use the Grinding Angle Setter for Tormek app to calculate the USB height every few weeks and post a 140 & 130 projection height for my staff to reference.

Update: We've been using the retrofit for a couple of weeks now. We no longer need to adjust the height of the  USB because we have the additional span of the shaft. We haven't found any issue yet with having a longer shaft other than it makes our work easier. The standard threads are tighter than the acme threads on the original and the fit is a bit looser. This makes for fast adjustment against the wood block we use to align. My employees are very happy since this speeds up their work and they are commission based per-inch. We did a farmer's market and never had to change our USB height the whole day! We sharpened over 100 knives.
In any case, we are pleased. One improvement in the next production run will be to add 5-10 mm of threads at the lower limit to account for even wider knives and perhaps chamfer the end of the adjustment knob more for comfort. The all aluminum construction also seems to be self-lubricating against the USB, only concern there is wear...

Hi folks,

I've developed a retrofit for the KJ-45 to make it more like the SVM. If you, like me are frustrated with the KJs, take a look! I also made the shaft longer and used a standard vs ACME thread.

https://magnoliaknife.com/products/tormek-kj-45-adjustable-retrofit

We'll be using these in our business over the foreseeable future I will keep an eye out for any issues.

Interesting, what was the impact of users leaning on the shaft?

[Novelty]

This qualifies as an "improvement" to an existing patent according to my attorney which; in the U.S., is permitted.
Novelty
The improvement must be new and not known or used by others in the country.
Non-obviousness
The improvement must not be obvious to a person having ordinary skill in the area of technology related to the invention.
Usefulness
The improvement must add a new function or extends the existing function of the invention.

Many people already have KJ-45's since that is what is coming with all the "kits" that Tormek makes and generally is what people seem to start out with. Will see if people buy it or ask for the whole thing as a single unit - that might qualify as an infringement though since I'm not extending the use of an existing product (the retrofit) so I doubt I'l go there. Also, since people would be buying a KJ-45 anyway, what would the damages be to Tormek - basically none.

If you can't find an SVM-45 and only have a KJ-45 I've made a retrofit for the KJ-45 that makes it adjustable.

I'm not sure yet if it will fit the SVM-140 yet since I don't have one.
https://forum.tormek.com/index.php/topic,5532.0.html

https://magnoliaknife.com/products/tormek-kj-45-adjustable-retrofit

Thanks for your work!

SVM-45's are nowhere to be found (if you can find a good source LMK!) - so this lets anyone that wants the adjustable-ness of the SVM-45 and has bought a KJ-45 fix that.

Yes - thanks, they were mislabeled - fixed in original post.

This primarily brings back the adjustable aspect that we lost with the KJ-45 that we used to have with the SVM-45, in addition to making the shaft longer than the original SVM-45. On the KJ45 there is only a plastic post that is split so retrofitting it without something like this is likely to be very tenuous.

Hi everyone,

I've developed a retrofit for the KJ-45 to bring back the adjustable attribute of the SVM-45 - there's a link to a video at the end of this post.

Update (5/7/2024): the kit  is now available on our website:
https://magnoliaknife.com/products/tormek-kj-45-adjustable-retrofit



Problems with the KJ-45
1.      It's not adjustable, you can't make micro adjustments easily, rendering the wood block technique less useful.
2.   Tool rest handle is too small, long blades pull the knife towards you.
3.   Occasionally you inadvertently use the "short stop" without realizing.
4.   The self-centering aspect is generally solving a low priority problem – we've never-ever had a customer complain about it.
5.   Plastic shaft is not as sturdy as it needs to be.
6.   Smaller torque screw is hard to get tight.

Problems with the SVM-45
1.   Shaft is slightly too short to accommodate very short blades without adjusting tool rest height.
2.   Plastic tool-rest wears out, we wrap electrical tape around the treads to establish tension... after three years it is now stripped.
3.   Not "centered" – though we have not found this to be a real problem.
4.   It's no longer being produced (boo!)

Introducing our retrofit for the KJ-45
1.   Fits precisely into the jig KJ-45 jig.
2.   Fillet cut maintains alignment and allows for variable height
3.   Longer shaft – 20mm longer than SVM-45 handles smaller and larger knives without having to reset tool rest height.
4.   Aluminum guide and tighter threads provide a longer life and more friction to prevent changing adjustment during sharpening – variable friction using lock-tite.
5.   Patent pending since this is an improvement to an existing invention/patent

These will be available for pre-order on our website magnoliaknife.com soon – email me at vijay@magnoliaknife.com if you are interested. 


https://youtu.be/WiammYI1PIs