2x48 vs 2x72 grinder

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Jan 17, 2015
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Hi all, long time lurker, first time poster with a grinder buying conundrum. I've got a 4x36 benchtop wood sander, but that doesn't cut it for what I want to do, make knives and axes and such (pun intended). I've got a little cash burning a hole in my bank account so I figure it might be time to pull the trigger on something better.

I thought about building a grinder, but that could take me a while to find the right round-to-it, plus I'm not an experienced metalworker. I figure the time I could spend kludging one together and making it work right would be better spent learning to do what I actually want to do, making blades and other neat, sharp things. I want to spend south of $2,000 at the moment, which isn't a ton where grinders are concerned.

I happen to have a few 2x48 belts (they may be 2 1/2 x 48, actually) that I picked up with a whole mess randon of Klingspor paper, most of it in small rolls, from a salvage building supply place that folks donate unused or still usable stuff to. So that had me thinking about 2x48 grinders, which led me to the 2x48 Steele Grinder, which is ~$1,600 for the non-tilting model with a 2 horse motor wired for 1.5 horse with a VFD for 115 v house power. The flat platen on the Steele grinder has a neat design with a 2" contact wheel on top and a 4" contact wheel on the bottom. I figure buildind a tilting base similar to the one they sell wouldn't be too hard and I probably have all the steel I need for it laying around.

Alternatively, I could get a Brodbeck 2X72 with a single speed 1.5 horse motor, flat platten, a small wheel attachment and a 6-inch contact wheel for ~$1,840. I like that the Brodbeck tilts, but I'd have to paint, assemble and wire it while the Steele maching is pretty much plug and play.

I know most folks prefer the bigger grinder, but becuase I'm looking to do this for fun and not income, maybe the difference won't matter, at least in the next few years.

Some considerations: At some point I could probably get a VFD for the 1.5 horse single phase motor that comes with the Brodbeck at this price, or even upgrade to a 2 or 3 horse motor and VFD down the line. But I'm pretty clueless about anything electronic. I figure it might be possible to turn the 48 inch Steele Grinder down the line as well and it's motor can be reqired to get the full 2 horses off of a 220 circuit if I decide to get one put in my shop.

So, what it boils down to is this question. Will I be happier right now and for, say the next 2-3 years, with a smaller variable speed grinder or a larger single speed unit? From what I've picked up 1.5 horses is the bare minimum for a 2x72 inch machine, so that power might feel better with smaller belts. I know the 42-inchers will wear faster and there's not as wide an array of selections, but they are cheaper, right?

Oh, and one more conundrum. The VFD on the Steele (A KBAC model like a lot of other grinders use) apparently doesn't play nice with GFCI/GFI outlets. And, of course, my shop is wired with GFCI outlets. If I use a spike bar, would that short circuit the problem (there's one of them there puns again...)? I guess I could always run a power cord out of the shop into the hall to a normal outlet... that would be stupid fun, or just stupid.

Love to here what folks think. Thanks in advance.
 
Oops, made a typo in the title. I meant it to be 2x48 vs 2x72, of course. That's what I get for posting late at night when I should be sleeping...
 
You will be far happier with a variable speed grinder than a single speed.

There are other budget grinder options. If you are willing to do some wiring, you can get a grinder chassis from Reeder with wheels for about $1k, a KBAC-27D for around $400 and an Iron Horse motor for around $220. With shipping and wiring, you would come in below your $2k budget. If you have 220V in the garage, you could save a good bit on the VFD by using an import model and building a dust-proof enclosure. There are many more options that have all been discussed on the forum, you can use the forum search to find a lot of information.
 
First, you'll have tons more belt options in a 2x72, so honestly for the price difference between those machines, that alone makes it worthwhile. I can't speak for Alec's grinder, but I have the Brodbeck so I can give you some input there.
1. Paint is unnecessary so you can totally skip that step if you'd like, although I did paint mine. The guys at Brodbeck are super easy to deal with and happy to help with any wiring/setup questions you get.
2. The tilting feature is awesome and totally worth it IMO, but probably not gonna be your final deciding factor.
3. GFCI outlet is gonna be a problem for the VFD that Brodbeck uses as well. I had to figure out a way to use a different outlet.
4. Pay more for variable speed, if nothing else! By far the most useful feature on a grinder in my experience. I learned how to grind on a single speed (fast AF!) 2x42 for the first 6 years making knives, and the amount of control I got when I finally got my variable speed Brodbeck kind of blew my mind honestly.
 
As has been said, you want 2x72, and you want VFD. My new grinder tilts and for the occasional operation it's great, probably not a huge requirement.
The best thing I did in my old shop was get an electrician down there. In one short visit he removed the GFCI, replaced some old outlets with deluxe industrial ones. Even better he installed a bunch of LED lights on a switch leaving my outlets for tools. I think he charged $300 for everything including the lights.
 
You are focusing on the TODAY here and now looking at Basic Models, and I learned LONG ago to see the Future Expansion Capabilities of any machine I purchase. I have well over 100K in my machine shop, and I learned to purchase what I wanted and needed with Expansion possibilities so I could market my services with those added Extra Features. I learned to buy what I wanted regardless of the price because I wanted "No Regrets" because I didn't spend the money to get what I really NEEDED. Having said all this I look at the "Reeder" Grinder and all the additional add-ons and bang for the buck. I have 6 grinders and would own a Reeder if they had been available when I purchased my TW-90....Think about the Future and look at the Accessories available from the different Manufacturers to see if they will enhance your capabilities in the future.
 
I also agree with the comments about variable speed. I would view it as a *necessity*, not a "nice to have" thing. (Otherwise you are burning blade tips and edges, and burning wood on handles). Also agree that addressing the GFI issue can be done affordably by bringing in an electrician.

I would research other grinder options (my ameribrade with VFD was in the range of 2k i think. If you need to wait a while to accumulate more $$ to get what you really need, i would do that..
 
probably an ignorant question, but.... if you use 220 for the grinder, aren't those outlets non GFCI?
 
"At some point I could probably get a VFD for the 1.5 horse single phase motor that comes with the Brodbeck at this price," Quote Not a option. Single phase motors can't be controlled by VSD. It would require changing out the motor to a 3 phase motor. I know it gets confusing but for VSD it requires a 3 phase motor. YES there are VSD that take single phase and produces 3 phase but the motor always has to be 3 phase.
 
I have no idea what a spike bar is, but I'd just swap out one of your GFCI outlets for a regular one and call it a day.
As for variable speed, LCoop is correct. You're not going to get very far wiring a VFD to a single phase motor. What you might consider: Find a used or surplus 3 phase motor (56C frame), or you can get a brand new IronHorse 1.5hp 3 phase motor for about $200, and then get a chinese open frame VFD for less than $100. The biggest consideration for the Chinese VFDs is that you'll need to keep the dust out of them, and they require 220VAC for anything over 1hp. The advantage, though, is that you can get into a variable speed setup for relatively cheap, and upgrade to a KBAC-27d when you get the funds.

As for "turn key" vs "assembly required" I wouldn't even give that a thought. Even if it took a couple days to assemble, it's a one time thing for a machine that will last you decades if maintained properly.

My vote would be for the 2x72 with variable speed.
 
I'm as rook as it gets but what the heck, my $0.02...

I just built a homemade 2 x 48 using a single speed buffer as the motor. Worked OK, and then I discovered treadmill motors. Retrofitted a 2.5hp DC motor with a $30 speed control to my grinder.

The variable speed is absolutely a great feature to have. I chose to make a 2x48 because I'm really limited on shop space and the depth of a 72" was unreasonable. The 48" is nice and compact.

I've had no issue getting belts - 60 grit ceramic up to 220 zirconium to 600 AO. In the $3/each range.


Lots of changes coming on the Mk3 I'll eventually build - but for $300, I'm cool with it.
 
Thanks for the feedback so far. Sounds like variable speed is a hugely popular feature. And I'm not surprised that most folks are pushing the 2x72 size. Belt availabilty aside, what are the real world differences between the two sizes that make the big boy so much better? Remember, I'm not getting into this to try and make money/build a business. This is strictly for fun. I already run e a small video production business, so I know all about ROI and investing in the gear that will pay for itself over time. When I go into the shop, however, I don't want to worry about that. Rather, I just want to relax, take my mind off everything and make stuff, without blowing the budget.

I figure that, with a 1.5 horse motor on both the smaller machine will actually feel more powerful/have more torque because it's pulling less belt around. I get that a 72 belt will dispurse heat better. Other than that, what sells the big boy?

Oh, and about VFDs and single phase motors... I was under the impression that only 3 phase motors worked with VFDs until I came across this site: https://www.wolfautomation.com/blog/vfds-for-single-phase-motors/
I'm no electrician, and maybe the single speed motor that comes on the Brodbeck won't work with a VDF, but it looks like some can.

In looking at so many grinders over the past week, I forgot that Steele also offers a 72" grinder for less than $2,000 with a VFD wired 2 horse. Of course, it's set up for 220, so I'd either have to rewire it for a regular house outlet or get a 220 installed in the shop. I'd prefer to get something I can just plug in and get going, but I could probably figure out the wiring if there are good tutorials online....
 
Just sayin'...

I went down the single phase/110V rabbit hole and I never found a practical solution. Pay particular attention to the list of compatible/not compatible 120V motor designs in the article. Capacitor start are the most popular single phase by far (incompatible).

The DC 2.5HP motor isn't as torquey as an AC omparable motor, but unless you're trying to reduce 1" flat bar to razor blades - the DC is very adequate.

I also have not noticed any heat issue with the belts. Granted that none of my grinding sessions have exceeded the 30 minute mark, but I would think 20-30 minutes continuous blade grinding would show any issues.

With a 6" drive wheel I am able to hit north of 6000sfpm and separate belt splices (I was just experimenting!). I've since swapped to a 5" diameter and keep the motor limited to 3000rpm.
 
i made knives for 10 years without a vfd, with a kmg machine on the slow pulley. and when i got one i did not notice any huge change in anything. burned tips and handle material is from a combination of 3 things. too much pressure, a dull belt, and too fast of a speed. its easy to adjust the first two to suit the last one. thats why i would not consider it required. i think the lack of belt selection would be the worst part of using 2x48's.
 





I'm just trying to point out that availability isn't really an issue.

They're easier to store in a small shop too lol.
 
It's looking like the difference between the two grinder sizes boils down to physical size (in terms of the space a machine and its belts take up in a shop), longevity and avialability of belts. I knew going into this discuss that 72" belts last longer.
They aren't twice as big as 48" belts though, as some have stated. Their half again as big. So if 48" belts are have to a third as expensive, the longevity issue cancles out. It would mean belt changes more often, a slight annoyance.

A belt twice as big as a 48 would be 96". I'll be putting this into a one-car garage that's mostly filled (my wife would say crammed to the gills) with woodworking tools, so space is definitely a consideration.

Finally, there is the avialabilty factor. As Enzo's most recent post shows, there is decent avialabilty for 48" belts, though not all brands carry all models in 48".
 
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