Grinder belt speed?

noseoil

noseoil

Joined
Apr 24, 2013
Messages
408
I've been looking at grinders, pulley diameters & belt speeds. The more I look, the less I seem to know about it from researching online. Building a 2x72 single speed grinder now & looking into what speed I should be running on the belt. I'll be using it to do basic grinds & bevels, since the 1x30 is a bit too puny now, but it did get me started. I'm keeping it, but I need more power to speed things up a bit.

Here's my question. I know a single speed is going to be "wrong" for many things. A ceramic belt wants a high speed & pressure to run & cut well, but a nice finish belt wants low speeds to work properly. I'm running with a 1 hp 1800 rpm motor (direct drive off the shaft, 13 amp) & can use a 4", 5", or 6" drive to start work. The speeds I can choose from would be about 1870, 2350 & 2800 respectively, from those drives. Would I be better off using the larger drive diameter to do my basic grinding (36-120 grit)? The 1 hp motor is a minimum size at this point, the speed would be ok but a flat platen takes more power to run when working than a wheel. If I go too high on the initial speed, I'll drop the belt speed a lot when leaning the motor at the platen. At lower speeds, it will be able to use the hp available, without bogging down too much.

I guess I can always drop the diameter a size or two for finishing with the finer grit belts, since a small drive would only be another $45 at a later date. So that's the issue, which size would be best (or is it really worst?) as a starting point to use this type of setup for my work with those grits?

Also, should I be considering a completely different type of belt than a ceramic, if I'm limited on speed? Anything has to be better than this HF 1x30 for making blades!
 
Personally I would save for a vfd and motor that runs off a vfd instead off all the different drive wheel sizes if your going with direct drive, or consider not going direct drive and using step pulleys. It will be so much easier changing a belt speed than taking on and off drive wheels. By the time you buy all those drive wheels you would almost have the vfd and motor. IMHO
 
The first grinder I built was two speed by way of changing drive pulley. My second is a vfd. I can't recommend enough how much better vfd control is.

But to answer your question the sfm tagged you are talking about I would try to get two pulleys that give you roughly 3000 sfm and 1000 sfm.
 
Noseoil, If you are like most other knife makers then you are going to spend a lot of time and effort setting up step pulleys and when you are through you eventually going to buy a 2 hp 3 phase 1725 motor and a VFD and wonder what you are going to do with your pulleys and 1 hp motor. You might make a disc grinder with the motor but it will be a single speed also so you will want a 1 hp 3 phase motor there as well and another VFD with a reverse switch. Buying stuff to save money almost always cost you more in the long run so save your pennies and buy some good stuff right of the bat and spend your time making knives instead of playing with your equipment. This is my opinion from experience. Larry


zYmxqSGm.jpg
xVhXapOm.jpg
 
Guys, thanks for the input on my question. Kuraki, I guess I'll go with your input, so thanks for your answer. I'll post something once it's up & running.

I'm on a fixed income due to retirement & don't have lots of "spare" cash. The VFD setup adds a lot of $ to my build, as I have the 1hp motor already. A "store bought" grinder model is out of the question for me, it's just just too much money to justify this late in life. I don't make knives for a living, it's a hobby at this point, so a step up to a 2x72 is still much better than what I'm using now. A few hundred dollars & some time is fine for my needs. I enjoy tinkering & building things in general, so the grinder is still a lot cheaper to build than it is to buy. The parts cost real money, labor is "free" for me.

Again, thanks for the input on my question, it's greatly appreciated. I'm enjoying the depth of knowledge here on the forum & everyone's willingness to share ideas & experiences.

P.S. Here's another project for anyone who's interested. You might want to skip toward the back if you want to see the finished result. If you like "process" have a look at what it takes to build. http://www.tnttt.com/viewtopic.php?t=60248
 
I have a 3k+ rpm motor on a VFD. I can say I never run it at full speed (60hz). That being said your setting at 2800rpm should be fine for "hogging out" material. The only issue you may have is bogging down a 1hp motor. Lower speeds are great for refined grinding. If you can tolerate the changing in between then you're just fine where you're at! Good luck and make cool stuff!
 
Noseoil if you can't find the drive wheels you want before you spend any money let me know. I can spin some out more likely than not. Like a 1.5" diameter for low speed, then you could use a light weight inexpensive Oregon blade maker fiber 5" for high speed.
 
You could always consider a used treadmill and use the motor and controller and get variable speed. That's what I have right now. Not a lot of hp but I have a lot of control. Just had to build something to keep the metal dust out. You might even be able to find one for free like I did. Just another option. I totally know about the tight money. I've got less than $600 in all of my equipment and materials spent over the last year.
 
I'm not exactly on a fixed income but my income tends to hover near the negative. I have lots of stuff collected over the years including lots of pulleys and motors. I'm always trying to use what is lying around. Guess what? After fooling around for a few months I bought a new motor and VFD. Like a few other things in life, if I knew then what I know now I would have done it sooner.

noseoil said:
Guys, thanks for the input on my question. Kuraki, I guess I'll go with your input, so thanks for your answer. I'll post something once it's up & running.

I'm on a fixed income due to retirement & don't have lots of "spare" cash. The VFD setup adds a lot of $ to my build, as I have the 1hp motor already. A "store bought" grinder model is out of the question for me, it's just just too much money to justify this late in life. I don't make knives for a living, it's a hobby at this point, so a step up to a 2x72 is still much better than what I'm using now. A few hundred dollars & some time is fine for my needs. I enjoy tinkering & building things in general, so the grinder is still a lot cheaper to build than it is to buy. The parts cost real money, labor is "free" for me.

Again, thanks for the input on my question, it's greatly appreciated. I'm enjoying the depth of knowledge here on the forum & everyone's willingness to share ideas & experiences.

P.S. Here's another project for anyone who's interested. You might want to skip toward the back if you want to see the finished result. If you like "process" have a look at what it takes to build. http://www.tnttt.com/viewtopic.php?t=60248
Click to expand...
 
You must log in or register to reply here.
Back
Top