2x72 grinder question

J

jakeotter

Joined
Aug 29, 2014
Messages
32
Hi everybody,
I'm considering purchasing a Polar Bear Forge kit to build a grinder. Originally was going with a Coote grinder but have been leaning to toward the GIB. I'm looking at having about $750 to go into this initial purchase. Eventually buy a VFD, etc... Once funds allow. I was sold on the Coote but the GIB seems like perhaps a better grinder if built correctly. The one huge con with the GIB is that I won't be able to have variable speed for quite some time and I don't think I can use step pulleys on it... ? I haven't seen pics / info on that...

Do you all have any opinions one way or the other? Thanks!
 
Congrats on the decision to get a 2X72" grinder Jake - what part of the world are you in?

Now, just what do you plan to use the grinder for? Only profiling? OR - for all phases of knife making? What is your level of grinding skill? The reason I'm asking these questions is because a single speed grinder will only do one phase of grinding well. It takes a real expert to grind bevels at 4,000 SFPM, while grinding profiles at 1200 SFPM is really slow go.

Do you have a spare motor laying around to use? OR will you need to buy a motor? If you're planning to buy and your motor is going to cost $100 or so, then spend $127 shipped for a 2hp 3 ph motor and $116 or so for a cheap Chinese VFD and have variable speed now. Yes, the VFD is NEMA 1 and open to dust. You can put a filter over the air inlets to protect from dust and it will last longer than you might expect. I've been running a similar setup for the last year, just blow dust off filters from time to time, maybe even replace filter.

A direct drive with VFD is by far the best way to go, runs quieter and smoother than pulley setup - I've had both.

Ken H>
 
Here is a thread showing a GIB build with pulleys: http://www.bladeforums.com/forums/showthread.php/878293-Starting-a-GIB-grinder-build, but I don't suggest you do it that way. Using a VFD is a much better route to take. By the time you buy everything you need to set it up with pulleys, you will have spent a third of what a good VFD costs or as much as one of the Chinese versions. Like KenH says, direct drive with a VFD is the best way to go.
 
Thanks guys I'm fairly new to knife making but have been making them for few years now. Never worked with a 2x72 tho. I even thought of a grizzly grinder for now but just seems like a waste. Some ppl love em, some hate em, and all agree you'll want to upgrade eventually.
So I figured made sense to do it right first.

Also is there a budget VFD and motor combo you can think of? I have a 1725rpm motor but only 3/4 hp.
 
I use a Iron Horse 1-1/2hp 3ph 1750 motor with a KABC-27D VFD on my GIB. It's not the cheapest combination, but I would not change a thing. For more info, use this custom search engine:

Custom Search Engine

Search for "GIB build", "Chinese VFD", "Motor for GIB" and you will find a ton of information.
 
I'm in the same boat as you and im curious why you picked the GIB over the Coote?

Thanks
 
Some people see getting unsealed motors and cheap vfd' as throwing money away. If you know they will burn up at some point and you view them as a consumable then you can get up and running cheap. I have had $100 vfd and a $60 motor running my shop for almost a year now. I have been able to make somewhere near 30 knives with this setup. So the investment has really paid for itself. Maybe I'm just lucky.
 
For $750 I got an Oregon blade maker grinder, Vfd and motor on eBay and it has been great
 
One option for a more affordable VFD is to go with one of the Chinese VFDs from fleabay. You can get a 2HP VFD for about $100 to $120 all day long.
Then find a 1.5 to 2HP 3 phase motor on the cheap. I see them for $75 to $150 all day long as well, for perfectly usable surplus motors. With just a few dollars worth of electrical odds and ends, you should have a serviceable VFD for about $250 to $300 all together. You can save a few bucks by hardwiring the VFD and motor, and obviously the cheaper the motor is, the more you save too.

The biggest thing to consider is dust control, as the Chinese VFDs are not totally enclosed. wrapping some filter material around the case and blowing it off from time to time should be adequate. Some guys build their own enclosures. It also helps to have an understanding of programming VFDs, as the instruction manuals that come with these VFDs are close to worthless. You can find a few walkthroughs on youtube or a handful of internet forums if I'm not mistaken.
 
Not to influence your choice in any way, but just wanted to say I have used a Coote for 15 years without a problem, and it may last that long again. It's a darned good product and very reasonably priced.
 
I ended up doing the GIB bc turned out to be a better deal for my particular situation. I wanted a KMG style and already had access to to a single phase 1725 motor. I plan to just run slow single speed only then when funds allow upgrade to a 3450rpm motor and VFD. I also have the necessary tapping tools, drill press, etc. with the money I was saving buying the GIB kit I was able to buy all KMG wheels as well which should be awesome. I was sold on the Coote and think it's a great grinder, the GIB just seemed better deal for my situation and I liked I could customize it to my liking.
 
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