SJ-1 Grinder Test & Evaluation

Darrin Sanders

Knifemaker
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Ok, I received the grinder from Hank and got it running today. There were several issues. Some of them could possibly be overlooked and some could not. Here they are in the order that they were encountered.
1. Packaging was terrible. The grinder was literally hanging halfway out of the crate. I'm pretty sure that the main issue was that the grinder was just setting loosely in the crate. Bolting it to a solid base would probably eliminate this. I know that there is always the possibility of damage in transit but wrapping an object of this size and weight with bubble wrap and simply putting it in a crate is asking for trouble. The only damage was to the round cover on the end of the motor and I was able to correct this in just a few minutes. It could have been MUCH worse and I honestly don't know how it wasn't.
2. No instructions. This grinder has a few features that are completely different from the other grinders I have used and if I wasn't fairly knowledgeable about how grinders work I wouldn't have been able to figure them out. I guess what I'm trying to say is that a new maker buying his first grinder would be confused about several things when setting up this grinder. This could be fixed with a decent set of instructions.
3. The belt tension assembly doesn't have a handle to release tension. You have to squeeze the belt together with one hand and lock it in place with a small lever to change belts. When releasing the tension I found it hard to release slowly and it usually snapped from zero to full tension all at once. I believe this to be extremely hard on belts. Again, I may be missing something but without instructions I can't really be sure.
4. Tracking-Once adjusted, tracking was rock solid but adjusting it was the problem. I couldn't get the belt to track exactly where I wanted it to. Instead I had to get it as close to where I wanted it. The main issue was when I wanted the belt to run dead center on the platen. It refused to do so. Running the belt slightly to one side or the other was not a problem and like I said earlier, it was rock solid a little off to either side but dead center was a no go.
5. SPARKS-The 48" belt length mad a huge difference in sparks and grit being thrown back at you. So much so that I found it extremely distracting. Other people may be able to get used to this but I don't think I would ever be able to overlook this issue.
6. I started off grind a heat treated 1095 blade that already had bevels established. The cutting edge on this blade is 3.5" from plunge to tip, 1" wide from edge to spine, .160" thick, & was at about .050" at the edge. I started grinding with a 40X belt with the grinder running at full speed. By the time I got all the decarb ground off both sides and the edge down to about .025" I decided to put on a 120X belt. This is when I noticed that the tracking/idler wheel was extremely hot. This took no longer than 3-4 minutes yet the wheel was much hotter than any wheel I've ever felt on other grinders. I can't be absolutely sure but I believe that this would reduce bearing life drastically. Once I changed to the 120X belt and let the wheel cool, I ran it at 50%-60% speed and the wheel got warm but not hot. So I don't think you would be able to run this machine at full speed for very long at all. I don't run my grinders at full speed very often but when I do I don't want to have to worry about heating issues. Other makers may be able to overlook this but I couldn't.
7. VFD-Before I could get the blade described above ground to 120X, the VFD started snapping, popping, & hissing and burnt up. I was afraid of this when I saw that it was an open design but I had no idea that it would fail that quick.
Would I recommend this machine at this point? Absolutely not! Could these issues be addressed and make this a serviceable machine? Yes. How much would addressing these issues raise the price? Not sure.
My final thoughts are that your money would be much better spent elsewhere until the issues I described are addressed.
 
Your assessment is fair and will provide the maker with the feedback he was looking for and I would say he will be working on plans to correct the issues mentioned. Thanks for posting your review.
 
Good write-up Darrin. Thanks. I hope the manufacturer pays close attention to your assessment.
 
Darrin, I've never heard of this grinder. Is there a back-story as to why you are using this grinder, and do you have photos? You wrote a good review.
 
Interesting!

Hopefully they can beef up the design, it sounded promising with the size and flexibility.
 

Ok, Now I remember seeing this post. I'm curious about the idler wheel getting so hot. Did you see a design flaw, or is it just possibly a bad bearing. That is a huge drive wheel perhaps that's the reason for the small idler overheating. That little wheel must be flying when that big wheel is turning full RPM.

I'm curious as to what you are going to do with the grinder now. I saw the OP's offer of paying what you think it's worth. You don't have to say, but I'm curious what you will do with it.
 
On the open VFD, those MUST have a filter over the air inlets, or mounted inside a good box. For a full time knifemaker I'd think inside a box, or even better a NEMA 4 VFD. For my hobby use, the open VFD works pretty good with inlet filters AND mounting the VFD away from area of sparks 'n metal dust.

It sure sounds like a good honest review, good job Darrin - and looking at photos on website and linked thread I can see each issue mentioned. Interesting design.

Ken H>
 
Ok, Now I remember seeing this post. I'm curious about the idler wheel getting so hot. Did you see a design flaw, or is it just possibly a bad bearing. That is a huge drive wheel perhaps that's the reason for the small idler overheating. That little wheel must be flying when that big wheel is turning full RPM.

I'm curious as to what you are going to do with the grinder now. I saw the OP's offer of paying what you think it's worth. You don't have to say, but I'm curious what you will do with it.

Not sure about the wheel overheating but Hank is sending another VFD. I will put it in some type of enclosure and do more testing after that. Not sure what I will do with it once testing is complete.
 
It did look and sound good. They had the right guy doing the testing. I hope they are able for help you correct all the problems.They sure are going to benefit from your use of it.
Frank
 
Yep, good stuff. I'm glad you got it, as opposed to some noob (no offense noobs), that wouldn't know what to look for and generate unfounded excitement, leading to lots of disappointed other noobs. ;)


Honestly because of the market we've created for 2x72 belts, it really makes very little sense in most cases to utilize any other size.
 
Hi all, I'm the seller and I would like to answer to the points Darrin made, but first thank Darrin for his input, that means a lot to me and to other knife makers.

1. The grinder was actually bolted in the crate upon shipment, I'm not sure how it ended like that to your hands, but I will make improvements on that, I think changing to industrial plastic box might work.
2. Yes there was no instructions inside the crate and may rise confusions to buyers, this machine is just entering USA market and after I gather enough information from this test assessment by Darrin I'll make a decent instruction and put it in the package for later buyers.
3. I'll make another post following this one to show how to change belts on this grinder.
4. I'm not sure how can the belt to be set exactly at each side of the platen but not able to be at the center of it, I run a little test myself this morning and I don't have a problem with that. Darrin would you please make a video of that so I can tell which part is wrong ?
5. Sparks. It's one issue that can not be fixed with this machine, because it's set at 48 belts, but you can try other better belts to reduce the sparks, such as Norton Blaze belts.
6. The tensioning wheel does heat up when running at full speed, the one I'm using does not heat up too much after a 10 minute run at full speed (I didn't run longer because I don't need such aggressive grind power, but I'll make a test if needed). I think maybe it's the bad shipping caused some problem to the bearing in the wheel. Again, I will definitely make improvements on packaging.
7. The VFD is an open design, dust isolation action is recommended, but honestly I've used my machine at harsh conditions (with only a plastic bag covered on) and it have never showed an problem. Regardlessly, the grinder comes with 1 year warranty and if the VFD breaks without your abuse I will ship a replacement with all costs on my end.

Thanks again Darrin, I appreciate your thoughts on this grinder. Could you please make a full test on this machine, i.e. the small wheel, the tilt work rest, the vertical / horizontal feature, the rotary feature, are they useful to you, are there any improvements you think it can be made ?
 
Yep, good stuff. I'm glad you got it, as opposed to some noob (no offense noobs), that wouldn't know what to look for and generate unfounded excitement, leading to lots of disappointed other noobs. ;)


Honestly because of the market we've created for 2x72 belts, it really makes very little sense in most cases to utilize any other size.


I Concur. The only machine that runs a 2 x 48" is the Noob Crapsmans machine. Anyone getting serious would want a 2 x 72". The hot idler wheel sounds like a sloppy bearing to me as well. Darrin, thanks for your write up!
 
Hank, I don't have a video camera so I can't post a video. I have checked the bearing and there is nothing wrong that I can see but I can't tell whats going on inside. However it turns freely and doesn't make any strange noises. Like I posted above as long as the machine is run at approx. 70% or less then there is no problem with overheating.
I have tested all the features (tool rests, vert./hor., small wheels etc.) and they are all rock solid and work great. As a matter of fact, the rotary feature is absolutely great. Like I said, if the issues I pointed out are addressed this machine has the potential to be a nice machine.
 

Hi guys, I’m Hank Jiang from Shanghai, China and I’m a knife maker. With my resource in China and my knowing in knifemaking, I’m starting a business here on BF to sell knifemaking tools & supplies worldwide. Firstly I want to introduce the SJ-1 belt grinder to you.

The SJ-1 belt grinder is a compact, flexible and powerful belt grinder, it’s been popular among knifemaking society in China for years, known for stability and precision.

You would have thought that those issues would have been worked out in those first years
 
Hank, I don't have a video camera so I can't post a video. I have checked the bearing and there is nothing wrong that I can see but I can't tell whats going on inside. However it turns freely and doesn't make any strange noises. Like I posted above as long as the machine is run at approx. 70% or less then there is no problem with overheating.
I have tested all the features (tool rests, vert./hor., small wheels etc.) and they are all rock solid and work great. As a matter of fact, the rotary feature is absolutely great. Like I said, if the issues I pointed out are addressed this machine has the potential to be a nice machine.

Hi Darrin, do you have any phone with camera, or could you please borrow one from your friend. A video is very important for my reference to make improvements.
Also could you please post specified tests about the attachments and the rotary feature? How it works and if it's helpful to knife making, pros and cons.
Thanks.


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Attachments not working?

According to Darrin the attachments works fine, but he didn't make detailed assessments about that.
I think Darrin is pretty disappointed at this machine, I'm very confused how it turned out this way because this grinder has proved itself during past years in China, and Chinese folks are pretty picky at what they buy.


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