Northridge belt grinder

J

Jaimoe

Member
Has anyone seen or used one of these? They really look good and are reasonably priced.
 

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I pulled the trigger on one. Waiting for it to arrive. I will give a review after I have it set up and get some grind time on it.
 
I got the chance to examine one, up close and personal at the Blade Show. It appears to be a well made machine, with several of what I consider critical flaws. The "flaws" that I noticed, that would be deal breakers for me are as follows.

First and foremost are the use of the "shocks" for belt tension and to control horizontal tilt. Those shocks are nothing more then a money pit when used on grinders. Depending on how much you grind, expect them to fail sooner or later. As someone who does a lot of grinding, I tried the shock tension on my grinder(s), and none lasted more then a couple of months. Sooner or later grit is going to get into the shock seal and destroy it, forcing it's replacement. On the machine I saw, the shock was only a 30lb version, which isn't strong enough for anyone who is serious about grinding. I suspect that they used the shock because they thought it was "cool", and/or just don't/didn't know any better.

The the idler arm handle is WAY too short, even with the weak shock, it's a bear to get enough pressure on that tiny arm to change belts. It should be at least 6" longer,

The "knob" that tightens the tooling arm is on the wrong side (in my opinion). This means that your arms will be all contorted in order to pull on the tooling arm, hold down the idler arm, and tighten the tooling arm,

Something that I did/do not understand is the grooves they have machined into the drive, idler, and platen wheels. It's possible that on the drive and idler wheels the grooves are irrelevant, but logic tells me that with less surface area belt slippage (traction) would be an issue with the grooves in the drive wheel. Now I'm fairly certain the grooves in the platen wheels create a very unsafe condition.... if an unknowing individual is running the machine, and tries to grind on either of the grooved platen wheels, I believe it would shred whatever belt is on the machine.

In it's current form, it could be a passable grinder, but unless they make improvements based on knifemakers' needs, I don't feel it's ready for prime time. For me, in it's current form, I would have to do more then a little modification to be satisfied with it. However, I suspect that since it's fairly new to the market, and provided the producer is open to suggestion, it has the potential to be a very good grinder.
 
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Thats wat I like around here is the stright answers when someone asks a question about a new machine.
 
I "DID" like them when I finally found the correct size that I liked. But after having them fail a couple of times, and having to replace them, they quickly fell out of favor with me. As with others I thought they would be a "cool" alternative to the traditional spring setup..... but I'm a pretty practical/straight forward kind of person.... and far prefer something that works, with minimal maintenance and cost output.....so until somebody comes up with something more reliable and durable, I feel that the traditional spring for belt tension is the way to go..... of course unless spending money and replacing parts appeals to folks. :)
 
Thanks Ed for your honesty. I was almost regretting not ordering that grinder. Your opinion of the grinder makes me fell better about my decision. I went with the KMG 3 speed instead. That way I can upgrade my drill press as well.
 
Ed, for some reason I was thinking I'd read "somewhere" (maybe I just dreamed it) by mounting the shock upside down with the main body at top with rod on the down side the grit didn't destroy the seal so badly and it actually lasted good when mounted in that manner. How did you mount your shocks?

Comment on the tool arm tightening knob - I put mine on the left side also, I use my right (dominant) arm to pull down the idler arm and left hand to tighten knob. Having knob on right side would be awkward for me. That's why they make chocolate and vanilla ice cream :)

I've been using a compression spring just like in your "How to" on grinders you posted a few yr back.

Ken H>
 
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the grit didn't destroy the seal so badly
Click to expand...

You did read that....and I did write it. In the beginning I mounted the cylinders with the seal facing up, and NONE lasted more then a couple of weeks, or maybe a month. Then it dawned on me that all the swarf was settling down on the rod/seal, and anytime I changed a belt, I was just grinding that swarf into the seal. Mounting the cylinder with the rod/seal downward does make the cylinder last longer, but in this case "longer" is a relative term. For me it only added a few days, to a couple of weeks to the cylinder's life versus having the seal facing up. When you compare the longevity/dependability/cost of a common spring, which can be measured in decades, versus the weeks/months lifetime of a cylinder, for me there simply is no contest.

I think the endurance of a cylinder has much to do with how much grinding, and on what, a person does. I obviously can't prove it, but most of the cylinder failures I had happened when I was making a batch of EBKs..... with G10 handle material....and the dust from that stuff is like little glass shards, and I suspect that had much to do with wrecking the cylinder seals. I also know that there are not a whole lot of folks out there who grind as much, or as often as I do, so for them, a cylinder MIGHT last a good long while, but they are simply not a smart choice for me.
 
I just built a grinder with a 100lb gas spring. I'm using an over-center cam tension system though, so it needs to be able to pivot to an extent, as well as have about 2" of compression stroke. I MIGHT be able to find a small enough spring to work as needed, with some kind of a homemade sliding guide, but a gas spring is the simplest choice, and only about $13 to replace. If I find that it doesn't last more than a reasonable amount, I'll probably make some kind of "bellows" out of some heat shrink or rubber tubing.

That said, if I was building a grinder that simply needed 30 or 40 lbs of straight up and down compression, I'd probably opt for a regular spring for simplicity and longevity sake.
 
Thanks for the input Ed - I was thinking I'd read that, but wasn't ready to say that you wrote it. I can see where G10 would be a real bugger on seals - you're grinding glass! well, glass fibers anyway. Those would be rough on seals for sure.... AND Ed, you will grind more in a month than I do in a yr!

edit to add: I wrote above "I put mine on the left side also" and went on to explain how that works just fine for me. Well, I just came from grinder, changed belts and actually noticed my movements...... I'm moving my knob on the right side. It just works better.

I put belt on using left hand to pull tension lever down, then have to move right hand to tension arm then adjust tool arm and tighten knob with left hand. I think Ed's right (as usual:)), it will be simpler to have knob on right side so the tension arm hand doesn't have to change.
OK Ed - I learned something new today.... from your writing. Thank you.

Ken H>
 
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We used to use protective boots on the shocks we had on equipment at work. That was 20 some years ago though and don't see much online for them. I'm sure something could be figured out to protect them from dust, old inner tube and a couple wire ties maybe?

One advantage of gas shocks is they stay the rated weigh no matter how far you compress them. Coil springs increase as you compress them.
 
I just recently purchased a grinder after considering 4 brands, Northridge being one. One of my criteria was to be able to flip to horizontal. At the time, and this was just 6 or 8 weeks ago, Northridge had yet to let anyone know what their options pricing was. One of the first to be revealed was the flip option....500 bucks. 500 bucks for an over engineered hinge. That's all I need to hear. I didn't stick around with them to find out what an 8 or 10 inch wheel might have been. In any event, I wound up purchasing an Esteem grinder from Bret Mathews. Search as you may, you'll never find an unkind word written about Brett or the grinder. These are 100% steel construction with a blue powder coated frame. Some parts are anodized, others, like tool arms, and work rest are left bare. The work rest is 3 axis compliant which makes adjusting very easy. I ordered mine with a 2hp motor (Leeson) with a VFD (KB Electronics). The Esteem is basically a Bader clone and built like the proverbial outhouse weighing in at 160lbs. Thats a fair amount of mass which keeps vibration to a minimum, though not as heavy as some grinders costing over twice as much. So thats my two cents and change for what its worth, but do check it out.
 
I've been mulling things over since my return from the Blade Show, and I even called and spoke with the folks at Northridge....with serious consideration for purchasing one of their grinders. I gave them my input on their machine based on all my years of using a grinder (there was one at the Blade Show, that I spent a lot of time going over), but I got the impression that they weren't overly interested in what I had to say..... I even offered them the opportunity to use my flat platen design on their machines, but again, I didn't get the impression that they had much interest.

I suspect that just about any of the available machines would be an acceptable purchase for those who are either "casual" knifemakers, or for those who are purchasing their first grinder. But for someone like me who has a lot of attachments that are based on a specific machine, and not readily adaptable to others, my most practical move would be to go with a machine that can use all the tooling I already have....in this case the KMG.

There are 3 things that I absolutely will not have in a grinder.....
1. A tooling arm smaller then 1 1/2"
2. Aluminum on the chassis or tooling arm
3. A gas strut belt tension system

Over the years all three of those things have proven to be trouble spots, requiring routine repair or replacement on any grinder where they are present. Of course those are my personal pet peeves, based on experience, and are certainly not universal.... but I have to believe that any knifemaker who has spent as much time in front of a grinder as I have, would have similar opinions.

After a lot of consideration, for me, the best option is to convert my existing KMG to direct drive, work out any bugs, then very likely will purchase a new KMG chassis and covert it to direct drive (unless I can talk Rob into building a direct drive chassis for me!) :)
 
If you are going to use a strut then you need to install a wiper to clean the grit off the piston before it slides into the cylinder. Find some good heavy felt about 1/4" thick. Punch a hole in the felt that will be a tight fit on the piston, remove the rod end of the piston and slide the felt piece over it. Slide it down to the cylinder and attach it to the cylinder with something to hold it in place. This will prevent a high percentage of accumulated grit from getting to the seals.

Don't use a strut myself but if I did, this is what I would do.
 
I agree. I didn't try the felt on those that I used, but did install a "boot"... ONCE, like the one you see on many off-road shock absorbers, just much smaller :) ..... but the boot got burned/melted off from sparks (I'm assuming) after the first session of rough grinding, and the "strut" failed shortly there after. I admit that the "cool factor" of having a strut is what sucked me in initially, but in reality, a strut falls utterly/miserably short of the durability and reliability of a simple spring for belt tension.
 
Ed, I wanted to circle back to your point about the KMG belt tension pivot arm being too short. I had said that I never found it to be a problem.

So I'm out grinding all day yesterday and I recalled this conversation- and then it dawned on me. The reason I never have trouble is because I always release the locking tension handle when I change belts! Then I put the new belt on, compress the pivot, slide the tool arm out to take up the slack, and then tighten down the locking handle again.

It never occurred to me that I was doing all these extra steps because it only takes seconds. But sure as anything, just trying to compress the spring and swap belts is no small feat.

Head slapper for sure. Looks like I'll be making an extension arm!


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I just contacted them with the same concerns Ed mentioned. They told me they were making a ratchet devise (like tw-90) to replace the piston. They also told me a longer tension arm was not a problem for them to make me. Definitely two good fixes.
 
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