Thinking of a new grinder..... but oh, the hurdles

EdCaffreyMS

EdCaffreyMS

"The Montana Bladesmith"
I've been considering a new grinder for the shop, and while it's no secret that I have been a fan of the KMG for a long time, some recent long/hard thinking has brought me to the conclusion that there is simply not any 2x72 machine out there that I could purchase, and use right out of the box, without at least some modifications.

I guess this is partly a rant, in that I have spoken to most of the producers of 2x72 grinders with suggestions on how to improve their machines for the knifemaker, but it seems nobody is listening.

Here are a few of my inputs/points on various machines that I have considered/am considering....

KMG- This is the grinder that has inspired all kinds of clones..... its built like a tank, and although its dirt simply, it's overall what I consider the best grinder for the money out there today....... but I would prefer a direct drive model, and the idler arm is way too short... with not enough leverage for changing belts (on my current KMG I added 12" to the tooling arm right out of the box, otherwise changing belts can be a difficult ordeal) In my mind this is currently the 2 x 72 grinder with the least amount of flaws.

TW-90: I simply will not own a machine with anything less then a 1 1/2" STEEL tooling arm. Weight and rigidity are very important for smooth operation. Aluminum tooling arms get chewed up by the clamping bolt, and I have personally been in 3 different maker's shops who dropped the 1 1/4" aluminum tooling arm, and it "tweaked" so badly that it required replacement. At the price point of this machine, I simply cannot see spending that much and not have it up to my standards out of the box. Were this machine built with a 1 1/2" tooling arm, I MIGHT consider it the best 2 x 72 machine.

Northridge grinder: This is one of the newest entries into the field, but..... another grinder with an idler arm that is way too short. I have also come to detest the use of the "cylinders" for belt tensioning....every single one of these devices I've use has failed sooner or later....and I've ended up gong back to a spring. While this might not be the "coolest" thing, it's reliable and durable (a spring for belt tension).

Wilmont: While the overall design of these machines is good, their fatal flaw is the belt tension mechanism(s)...... a tension spring is simply an all around poor choice for a belt grinder, unable to overcome the leverage of the machine, especially in slack belt grinding situations. In other models the use of the "cylinder" for belt tension is simply unacceptable for me. I've also had some major repair encounters with these machines.... a situation where I spent two full days repairing "new" machines that should have been "right" in the first place. It might have been an isolated instance, but it was enough to give me a less then favorable opinion.

Bader BIII: Bader has been around since before I started knifemaking, and they have always been a good machine, I've personally had bad experiences dealing with them in the past, so I guess my view of the machine is somewhat jaded.

Burr King: Another machine that's been around for a long time, but because of the design, I find the machine cumbersome to use and adjust/change attachments.... it's just not for me.

The first three are the machines that I have been considering.... Personally I would not even consider ANY machine that is built with, or uses any type of "tubular" steel or aluminum in it's construction or tooling...which is why I didn't mention grinders such as the pheer.

I guess where I'm going with all of this is first, why is that those who produce knifemaking grinders never seem to listen to the input/needs of the knifemaker? OK, that was a little selfish, and I know each knifemaker has their own list of "must haves" when it comes to a grinder, but as someone who has been using 2 x 72 grinders for 30 years, and has used just about every machine out there.....I have to wonder if I'm the only one who sees these things.....and I suppose I'm just gona have to choose something that requires the least amount of modification to fit my needs/desires.

Right now, if I could get a KMG, with a longer idler arm, and a direct drive motor mount/option, I'd be all over that. I'm actually considering buying a new KMG chassis, and seeing if I can modify it to a direct drive.....which might require more machine work then I have the capacity to do. But on the other side of the coin, I find it a bit ironic that I'd purchase a grinder, and then have to spend more money, and a chunk of my time to make it "right" for me.

I mean no disrespect to any of those producers/machines I've mentioned, and am speaking strictly from my own opinions and experiences. I simply would like to see those who produce grinders to actually listen to their customers, and fulfill those customers' needs. So, am I the only one who wishes for "more" when it comes to a grinder....or am I just being a picky son of a gun? :)
 
I'm with you on the direct drive KMG option. Mine is variable speed and the pulleys / belt are superfluous. If anything they are a point of vibration.

I've not had any issue with the tension arm length.


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I still have and use one of my BIIs from the mid 80's and still think it's a heck of a machine.
After many years in the construction trade I learned early on to make my field tools do double duty within their limitations so I've always had that mind set. I do things with my grinders that I wouldn't have considered previously. Not always the safest thing but gets the job done. The most interesting 'new' grinder concept I've seen comes from TDM grinders. They have the direct drive option you mentioned but the tension spring is a coil with variable settings. This made a lot of sense to me...I like a tight belt when finish grinding and the belts perform better. No grinder I've seen hits every point on the wish list.

Rudy
 
I looked at as many images as I could find of the TDM machine...... Although the concept looks good, for me it's a no go based on how "lightly" its built (the materials used are too thin/light for my liking). Another aspect that turned me off right away was the tooling arms being tubular....which tells me the entire emphasis for that machine was to build it at minimal cost. What I did find interesting is the motor mount design...that could potentially be something that could be constructed of thicker/heavy materials and adapted to the KMG chassis for a direct drive retrofit.

I think that the TDM, along with most of the other machines would serve a hobbyist maker well.....in other words for someone who grinds occasionally, and who doesn't spend a lot of time in front of a grinder, they would be just fine. But for someone like me who uses a grinder EVERY day, and wants the most heavy duty, trouble free, and easiest to manage machine, there are just too many visual "red flags".

Anthony: Add another 8-10" to the idler arm of your KMG....you'll find that it will make your life MUCH easier. :)
 
That's a great direct drive adaptation to the KMG! I'd love to have a template of that adapter! I suspect that varying size motors might require some modification to the adapter, but I really like what you've done there. If I were you, I'd send that over to Rob Frink...... I think something like that would reduce his production costs, and make the KMG an even better machine!
 
Ed,
Like you I was mostly dissatisfied with just about all of the current offerings of 2x72s for one reason or another. I built a NWGS years ago when I was first getting into knife making, and IMO, it's still one of the best bang for the buck DIY options out there when it comes to cost and versatility. That said, I did make several modifications to the original design where I saw some room for improvement.

I recently decided it was time to upgrade, however, and I got to seriously considering what's available. The KMG had always been my first consideration due to price vs function, but after reading a few horror stories, along with the short comings you mentioned, I more/less wrote it off.
My next choice would have been between the Wilmont TAG grinder and the TW-90, but for what they are, I think they're both about $1000 overpriced, and I really didn't like the way the TAG tilts, or the flat platen on the TW-90, plus I really don't like that I need tools to adjust certain things. Don't get me wrong, I think they're both great machines, but they're a very heft investment, and at the end of the day, if I'm spending that kind of money, it better be exactly what I want.

Since nobody made exactly what I wanted, I decided to do just that, and I designed and built my own.

Now, I must admit, it breaks a couple of your rules in that it's made almost entirely of 6061 aluminum (including tool arms, though they are 1.5"), and it uses a gas spring (on an over-center cam system though). Of course, it could be made out of anything I suppose, but aluminum is much cheaper and easier to work with.
While aluminum is a bit softer than something like 1018 or A36, I personally don't think it's significantly so. Yes, they do mar a little more from handle screws and what not, but one thing that helps is to de-burr the ends of the screw/bolt threads. I did use threaded inserts any where a thread would be moving in and out repetitively, as well as bronze bushings where applicable on moving mated surfaces.
I initially tried steel for the arms, but I like the weight savings of aluminum and I'm not noticing any significant wear or galling yet.

http://knifedogs.com/showthread.php?44012-Almost-done-with-a-new-grinder-build
 
Ed, don't overlook the Esteem. It's configured similarly to a Bader B3, but it's a bit more robust. Also, Brett Matthews is a good guy, and has taken good care of me when I have questions or random ideas. He's also seemed open to customizations, though I've not ever sprung for any. I'm super happy with mine, and Karl Anderson swears by them as well. You're welcome to give me a call if you want to discuss (512-360-0220), and I'm sure Karl would have some things to add as well. It maybe isn't the best grinder on the market, but I'm pretty convinced that it's the best grinder for the money on the market.
 
So I got to ask what is the advantage to direct drive when considering a grinder???
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For the casual knifemaker I doubt there would be any notable difference, but for those of us who grind every day, here's the difference...... with a belt/pulley system, there are generally 2 extra points of slippage (the motor pulley and the pulley on the drive wheel shaft. There are FOUR extra points of friction.... the two pulleys and the two drive wheel shaft bearings. These additional parts also lend themselves to inducing more vibration. All these things equal out to less power to the grinding belt. As I mentioned, to the casual knifemaker, it's likely he/she would not notice.....but I have/can. With direct drive (and using a rubber coated drive wheel), slippage and friction issues are greatly reduced, meaning more power/force to the grinding belt. And, provided the drive pulley is correctly placed on the motor shaft, far less vibration. All of those reason are whats driven me to move up in HP on motors as time has gone by. I started with 1hp motors, then went to 2hp motors, and now am currently at 3hp. Assuming my line of logic is correct, if I can successfully convert the KMG to direct drive, with a 3hp motor, the smoothness should increase, and the power SHOULD be similar to a V-belt driven grinder with a 5hp motor.

Based on how robust the KMG is built versus most other machines, I feel confident that it will easily handle the additional power, where as I have doubts that most of the other machines would.....at least not without major reinforcements to critical stress areas.

Ed, don't overlook the Esteem
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I didn't.... I looked at it, but rejected it based on the tooling arm size, and the fact that I would have to completely rebuild all of my existing tooling because of the "offset". Since the KMG is built with 1/2" steel/plate, in order for the wheels/contact wheels to align properly, the tooling (platen or other attachments) must be based off that 1/2" offset. The majority of grinders are now being built with lighter/thinner materials, which would mean I'd have to replace ALL of my attachments with new ones made to match the offset of whatever the grinder might be. While that grinder might be good for someone buying their first machine, for anyone who is established, and has existing tooling/attachments that won't work with the machine....it would be a step in the wrong direction.

As things are right now, I'm leaning towards converting my existing KMG to direct drive via the method that Matt posted as an experiment, then if the "bugs" are not too great, I'll likely purchase a new KMG chassis and make it a direct drive.
Again, none of that is a slight towards any of the machines I've rejected, there are simply reasons that they won't work for me. I have to believe that the term "best" when it comes to a grinder must be based on many factors, not only for the grinder itself, but also those individual factors of each knifemaker.
 
My $.02

For the TW-90 tooling arm, why not mill pockets and use hardened steel inserts? This would keep them from getting chewed up.

I suppose this is the least of the aluminum arm issues as compared to the size and potential for tweaking but there must be a mod that would allow the TW-90 to accept standard 1.5x1.5 arms.

I'm not a knifemaker but a former tool & die maker and it's been my experience that something can always be done to fix/improve tools.

Although now you're talking about putting more money into a machine that is already top dollar.
 
Although now you're talking about putting more money into a machine that is already top dollar.
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Personally, that's one of the biggest reason the TW-90 isn't for me..... spending that much on a machine, then having to spend more money and time to get it to a usable state for me just doesn't make good sense. I've looked closely at the ones I've used in other shops, and changing it to a 1 1/2" tooling arm just isn't feasible....it would basically require and entire overhaul of the machine. Another downfall for me is the flat platen that comes with that machine.... its just not up to par. I suppose that having used the flat platen that I designed for all these years, and knowing it's versatility, makes most other flat platens seem inferior to me.

I've pretty much come to the conclusion that the most practical route for me is to do what I mentioned in my previous post. Use my existing KMG as a test bed for the direct drive conversion, work any bugs out, then purchase a new KMG chassis and convert it to direct drive. I have a great deal of respect for Rob Frink, who came up with the KMG, and in my eyes spawned most of the "home made clones" that we see today. I wanted to run it by him, get his input, and if it's something feasible for him, give him the chance to offer it as an option on the KMG grinders....or possibly give him and idea for a new version of the KMG. We'll see what he has to say, and go from there.

In the mean time, I think I'll order the motor (http://www.electricmotorwholesale.com/LEESON-116107/) and controller (http://www.electricmotorwholesale.com/10001-KBAC-29D/)..... even if the direct drive conversion doesn't work out, these two items can be used with the current configuration for my KMG. My KMG has been around so long, that VFDs were not available when I got it, so I had to set it up with a 180V DC motor and a DC controller.... and the motor is getting pretty old and tired. :)
 
Ed, look at the Outlaw II from Outlaw Waterjet. Matt has a nice machine that will take your 1.5" tool arms. Mike Stewart of Bark River Knives turned me on to him.

He was at Blade this year with his grinder line. All my friends that saw it there rated it very well.

I'm looking to get one later this summer. Just got to make room for it in the shop...
 
Not a bad looking machine, but again, the offset of the attachments would be the downfall for me..... my attachments are all built with 1/2" material, matching the 1/2" offset of the KMG's "frame"..... the material on that grinder is much thinner/lighter, which means I'd have to rebuild all of my attachments with the correct thickness to match the frame offset..... and I suspect doing so would mean the material thickness of the attachments would be too thin/light (at least for my tastes). I have to also question the $850 price tag for just an unpainted chassis... seems kinda steep for what you get..... as a comparison, the KMG chassis is built out of at least double the thickness/weight of material, and is only $605.

As I mentioned previously, it might be a good choice for a "first grinder", but for someone who already has 2 grinders in the shop that use 1 1/2" tooling arms with 1/2" offset (me), it would not be a wise purchase.
 
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EdCaffreyMS said:
I didn't.... I looked at it, but rejected it based on the tooling arm size, and the fact that I would have to completely rebuild all of my existing tooling because of the "offset". Since the KMG is built with 1/2" steel/plate, in order for the wheels/contact wheels to align properly, the tooling (platen or other attachments) must be based off that 1/2" offset. The majority of grinders are now being built with lighter/thinner materials, which would mean I'd have to replace ALL of my attachments with new ones made to match the offset of whatever the grinder might be. While that grinder might be good for someone buying their first machine, for anyone who is established, and has existing tooling/attachments that won't work with the machine....it would be a step in the wrong direction.

As things are right now, I'm leaning towards converting my existing KMG to direct drive via the method that Matt posted as an experiment, then if the "bugs" are not too great, I'll likely purchase a new KMG chassis and make it a direct drive.
Again, none of that is a slight towards any of the machines I've rejected, there are simply reasons that they won't work for me. I have to believe that the term "best" when it comes to a grinder must be based on many factors, not only for the grinder itself, but also those individual factors of each knifemaker.
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That all makes perfect sense. Same reason I'll buy another Canon camera instead of a Nikon--all my lenses are already Canon.
 
That's essentially the plan. I just finished machining out the pieces for the mount, but I lack the machining capability to cut a 4.5" hole for the motor. I have a friend who has a much better equipped machine shop, and knows a LOT more about machining them me...... so he's gona "help" me with the hole.

My existing KMG motor isn't a usable option.... it's a 3hp,180V DC motor.... it's 26" long, and weighs in at about 130lbs. At the time I got my KMG, it was the only option for variable speed..... VFDs where not commercially available at that time. That motor is getting old and tired anyways..... so yesterday I place an order for a new 3hp/3 phase motor...... and the other parts I need to wire it into my existing KBAC 29D.

I have another student coming in a couple of weeks, so I'm going to wait until after that class to "experiement"..... it wouldn't be a good thing if I'm a grinder short with a student in the shop! :)
 
Ed,
About three months ago I purchased a Wilmont Tag 101 with Chris's small wheel adapter with the second 2" wheel that brings the belt down on both sides so you can truly get that small wheel size you are after.

Another plus is that he sells a rubber 70 duro meter drive wheel and I has not detected any slip.

Also My Finger Skins work excellent for handle sculpting on the Tag 101 with the Platen out and leveling the Pins/Loveless bolts.

The other group of 2 x 72's that you haven't seemed to mention is the Hardcore Products Machines. A machine I've had and used almost daily for about 17 years and the SMOOOOTHEST machine of them all! Direct and front wheel drive.:s11798:
So If you don't care about a 90/45 machine look at this one.

https://trugrit.com/index.php?main_...d=5358&zenid=4956c81829c6228396441161befe16ea

I'm sure you could talk with Scott and get a 3 HP motor put on it and if you want a 90/45 look at the Maximizer. I have not used the Max, so i can't offer any feed back for you there.
 
C Craft said:
So I got to ask what is the advantage to direct drive when considering a grinder???
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You remember how quiet 'n smooth my direct grinder ran? The pulley 'n belt system I had before wasn't even close! Before I went direct drive I made the statement "belt 'n pulley" are plenty good enough..... well, I ate crow. Not even close to what a decent direct drive setup will in in smooth.
 
Just an update..... I've cut the pieces out to convert my KMG to direct drive, and have talk to Rob about the idea of offering a direct drive option with his KMGs..... I know Rob well enough to know that he'll carefully consider the pro/cons of it, and who knows, he MIGHT offer a direct drive version of the KMG in the future.

The new 3hp/3 phase motor, along with a new 4" rubber coated drive wheel is on the way, and I've decided to use my existing KBAC 29D to run two grinders..... I have two sitting side by side on the bench, and as a safety precaution I have them wired into a toggle switch which only allows one grinder at a time to be powered anyway...... all it will take is multi-pole toggle placed in the "forward/stop/reverse" hole in the VFD, and a jumper wire for the power.

I'm going to hold off for a couple of weeks to get going on the conversion...... I have a student due in week after next, and am still catching up on the "Honey Do" list. :) I'll report back when I get the project underway.
 
Ed - I do think you're on the right track. I do agree (for what it's worth) a direct drive option would be a GREAT option for the KMG. It would actually be less expensive for the variable speed version. I talked to Rob and he didn't think a direct drive would be any smoother than his pulley arrangement. BE SURE to post a couple of photos of your conversion once you get to that point.

Ken H>
 
If the revamped grinder is anything like your knives Ed a video with a penny on the tool rest may prove your point of smooth vs one with pulley system.
 
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