Surface Ft / min for belt grinders -

[mikey]

Is this the table you were talking about? I've been looking at that one, but was thinking how to make the "T" handle geared in some way to turn to the angle easily and then have the upper "pin" have some type of lock nut / lever to hold in place. Base plate would obviously be different as this is designed for their machines..

View attachment 243291

No, that is the Glend0 Grind-R Table. I have that one, too. I meant the table on the Accu-Finish Series 1. It has a swiveling protractor like this:



The table can swivel up and down and is locked at the chosen angle with a pin that passes through a block with a locking knob:



You set the protractor to the desired table angle and slide the table over so it sits on top of the protractor, then you lock the knob under the table to lock the pin. This locks the table angle and you can then slide the table over to grind tools on the face of the diamond wheel.

Simple and very accurate but you would need to sort out how to implement it. I'm not saying you should go this way - just throwing out ideas.

 

[higgite]

This thread woke up some long dormant brain cells (I hate it when that happens) and stirred a memory of an article that I saw on the web a couple or four years ago and bookmarked for future reference. The article was on MachinistBlog.com and it was about modifications the author had made to a Craftsman 2x42 belt sander, making it suitable for grinding lathe tools. I had not noticed the author’s name until today when I found the bookmark and retrieved the article. It was posted by some guy named Mikey. Anybody ever heard of him?

Tom

P.S. It’s a great article. Here’s the link.
http://www.machinistblog.com/modifying-a-craftsman-2-x-42-inch-belt-sander-for-tool-grinding/

 

[mikey]

This thread woke up some long dormant brain cells (I hate it when that happens) and stirred a memory of an article that I saw on the web a couple or four years ago and bookmarked for future reference. The article was on MachinistBlog.com and it was about modifications the author had made to a Craftsman 2x42 belt sander, making it suitable for grinding lathe tools. I had not noticed the author’s name until today when I found the bookmark and retrieved the article. It was posted by some guy named Mikey. Anybody ever heard of him?

Tom

P.S. It’s a great article. Here’s the link.
http://www.machinistblog.com/modifying-a-craftsman-2-x-42-inch-belt-sander-for-tool-grinding/

Sorry, Tom, but that guy is not to be trusted. The article is too wordy, repetitious and he writes like a girl.

 

[DHarris]

Thanks Mike, I'll think about that idea - - hmmmmmm - ouch.

(thinking causes headaches in this old fart) - - an old engineer I used to work with would use the following phrase when he was breaking in a new hire / new graduate engineer - - " Teaching THAT GUY anything is like trying to pound S#!T thru concrete - it's really messy & not much gets thru!" And yes, I'm sure he used that phrase in reference to me a few time too!

Dave

 

[Alan H.]

Great question Dave, thanks for kicking this off. I dug into this before when trying to decide what speed to design into my KMG.

A well grounded machinist friend told me the following when I emailed him:

"Belt speed gets a little complicated. In general, ceramics need higher surface speeds to cut. Increased pressure is also required. If the abrasive and coating are designed to fracture in order to give sharp grains as the belt wears, higher speed and pressure are required. Bottom line it depends on what the abrasive are made of and the matrix they are imbedded in. I would look at the data sheets for the mfg. Hardness of the metal being ground is also a factor."​

So the conclusion I came to back when was:

1. Published information is hard to find. I even made the mistake of searching knife making forums and discovered just how many hundreds of "opinions" there are out there.
2. I do believe the answer is belt/abrasive specific as my friend pointed out. For example, as I understand it the 3M Cubitron belts need a certain minimum speed to cause the abrasive to fracture and refresh its cutting action.
3. I believe it best to call tech service for the belt manufacturer. For example, 3M has good customer support and yes, you pay for it when you buy their belts.
4. All the more reason to have a multiple or variable speed belt grinder.
5. Adequate power is needed.

BTW, I think this is consistent with what Mikey has shared with you.

 

[DHarris]

Thanks Alan!

 

[FOMOGO]

Sorry, Tom, but that guy is not to be trusted. The article is too wordy, repetitious and he writes like a girl.

And who says we no longer have a sense of humor in our "Golden years". Cheers, Mike

 

[mikey]

... A well grounded machinist friend told me the following when I emailed him:

"Belt speed gets a little complicated. In general, ceramics need higher surface speeds to cut. Increased pressure is also required. If the abrasive and coating are designed to fracture in order to give sharp grains as the belt wears, higher speed and pressure are required. Bottom line it depends on what the abrasive are made of and the matrix they are imbedded in. I would look at the data sheets for the mfg. Hardness of the metal being ground is also a factor."​

Alan, I wonder if there is a critical speed at which ceramic belts work at. I cannot verify your friend's statement because I'm stuck at a fixed speed of 3450 rpm but my impression at this speed is that the ceramic belts I used cut much faster and cooler, and with less pressure than my Aluminum Oxide belts. What's more, they seem to last much longer compared to an AO belt.

I've been thinking about the quoted information and I wonder if the ceramic granules and the magic stearate juju they're embedded in differs between manufacturers. That might account for the difference in our impressions. Regardless, there is no doubt in my mind that the Red River ceramic belts vastly outperform any AO belt I have ever used from any manufacturer at the speed available to me.

​

 

[Alan H.]

I am resisting the urge to launch into the "studies" again!

My friend and his friends seem to be fans of CubitronII belts from 3M. I once called 3M and they told me that I could run the belts at 7000 FPM with no problem. My grinder will turn up to 5500 but I rarely use it at that speed. I am fearful of being in the line of fire of a 72" belt coming off at 60+ mph and I personally would not want to go much higher than that. I know a knife maker who sustained an unbelievable laceration to his arm from such an incident. This is a very good reason to buy high quality belts with good joints.

I can personally verify that the Cubitrons make shavings on HSS. When I sharpen HSS there is a ball of "steel wool" like material in the quench pot that catches the sparks. It is quite interesting to see this and it also makes one then believe there should be some an optimum SFM. Here's a photo of the shaving notion from a 3M flyer.



To your point, I do believe this all has a lot to do with the specifics of the belt in question and unfortunately the info seems a bit hard to come by.

 

[Alan H.]

Alan, I wonder if there is a critical speed at which ceramic belts work at. I cannot verify your friend's statement because I'm stuck at a fixed speed of 3450 rpm but my impression at this speed is that the ceramic belts I used cut much faster and cooler, and with less pressure than my Aluminum Oxide belts. What's more, they seem to last much longer compared to an AO belt.

I've been thinking about the quoted information and I wonder if the ceramic granules and the magic stearate juju they're embedded in differs between manufacturers. That might account for the difference in our impressions. Regardless, there is no doubt in my mind that the Red River ceramic belts vastly outperform any AO belt I have ever used from any manufacturer at the speed available to me.

​

Mike, I think you meant Red Line ceramic belts. I have spoken to them three times on the phone since I too bought some of these belts directly from them.

The Red Line "Extra Premium" belts that you and I have are cut and joined by Red Line but the belt itself is actually made by Hermes. Hermes is a German company headquartered in Hamburg (Hermes Schleifmittel GmbH) and are one of the bigger belt makers like Norton (St. Gobain) and 3M. Red Line buys the belt material from Hermes and then fabricates the belts with taped and glued joints. So contrary to the markings on the belt, Red Line says they are bidirectional. (Note: Regardless, I will abide by the arrows.) This Hermes' belt abrasive is Ceramit®. Red Line told me the Hermes Ceramit is self renewing like the 3M Cubitron II belts. I have not yet spoken to Hermes directly yet but plan to do so and confirm the nature of the belt as well as asking them for their SFM recommendations for their Ceramit belts.

So I am not surprised at your assessment of the Red Line belts being excellent performers. I would expect that they would behave and perform very well.

Here are a couple of photos of the 2" x 72" Red Line belts that I have.
80 Grit:


40 Grit: