Maximum Belt Grinder Belt speed

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Natlek

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Jun 9, 2015
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I'm working to make two belt grinder with two wheels . One fast as it can be , one slow....And I can not find data which is maximum speed of belt ? Any help ?
 
Some of the ceramic belts are designed to run as high as 6,000+ SFPM, and even up to 7,000 SFPM. I wouldn't want a grinder to turn that fast, but some folks do use some very high speeds. 4,000 SFPM is my max and it will throw some sparks!

Ken H>
 
Thanks Ken ! If I correctly calculate , 7000SFPM is about 35m/s /meters in seconds / which sounds great . My disk sander has a 39m/s at the periphery and I like how quickly grinds steel and very little heat up .
 
I have been down this road befor and trust me it's not really worth it. I built my belt grinder to hit 10000sfpm. And yes it worked and I never had a belt come apart. I had belts come off the grinder and shoot across the shop like a drag car. I used it this way for years and years. And poo pooed anyone that advised me otherwise. I have now switched and could not be happier. There are a few times I miss the blazing fast speed but honestly most days not I don't even max out at 4500sfpm. There is a lot more control in the lower speeds. Also you brush a finger or nuckle on a 36gr belt going 10,000 fps and it's not good. I think if you built one good grinder with a VFD and 3hp 3ph motor with a max speed of around 4000-5000fps you will really like it.
 
You're going to be amazed at how much material gets hogged of with a good belt at 3600 sfpm. I can grind my primaries in 12 passes with a 36 grit 947 Cubatron and i'm probably only running a 3/4 hp DC motor, so I can't even lay into it that hard.
 
You can always take more metal off, you can't put it back on after a simple slip in the wrong place.
 
I have a small assortment of drive wheels for various belt speeds and for a while I was zipping along with 4500 SFM +. I now use a drive wheel that I had made that is 4 3/8" at the crown. It produces about 4000 SFM and I usually grind at about 3700 to 3800 SFM by estimation and that's what I can control and make the grinds that I am proud of. As always, It's just my opinion. Larry

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I found this data from Norton abrasive.............

RECOMMENDED GRINDING BELT SPEED

Heat sensitive materials,plastics, etc.5-15m/s

Stainless steel, high-speed steel& tool steel 20-30m/s

Sintered metals & carbides 8-15m/s

Grey cast iron & cast steel 30-40m/s

Titanium & similar alloys 8-15m/s Carbon steel 30-40m/s

Glass, porcelain & special steel 8-15m/s Brass, copper, zinc, bronze & tin 25-35m/s

Heat-resistant plastics 20-30m/s Aluminium & light metal 20-35m/s
Wood 15-30m/s

Varnish 10-15m/s
 
Those speeds above will be for a specific belt - perhaps one of the ceramic belts for the steels. For the heat sensitive plastics I'd think it would be a different belt than for SS. Do you happen to remember which belts they were recommending?
 
Ken H> said:
Those speeds above will be for a specific belt - perhaps one of the ceramic belts for the steels. For the heat sensitive plastics I'd think it would be a different belt than for SS. Do you happen to remember which belts they were recommending?
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Write this in google , it is [PDF] ...............technical information - Norton Abrasives
I found another useful things about belt tensioning

...........https://www.thefabricator.com/artic...elt-tensioning-overlooked-and-under-addressed
The vast majority of sanding and grinding equipment runs well under certain conditions. For contact roll heads made of steel or rubber that is 80 durometer (Shore A scale), use 20 to 25 pounds of pressure per linear inch of belt width. For combination heads (contact roll with platen) and platen heads, use 15 to 20 lbs. of pressure per linear inch of belt width.
Click to expand...
 
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Natlek your missing something very important. Certain belts prefer that speed, but making a knife your gonna be grinding wood g10 micarta brass aluminum mild steel hardened steel epoxy fiberglass etc. But ask anyone in performance cars or bikes. Faster means more money replacing stuff more often, Subaru station wagon going 300,000 Miles you bet, Subaru wrx souped up? Not likely. You sure your home built tracking and drive wheels are rated at 10000 rpms? What about your bearings?
 
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I destroyed the bearings in my contact wheels running then at 9000sfpm. These are expensive wheels from bemount (KMG). And the problem was much worse then a shot bearing. As the bearing started to go it some how started to wobble out the aluminium bore of the wheel. The bearing was then sloppy in the wheels hub. It is not fixable (with basic tools) and had to be replaced. Not a cheep fix considering thy don't give those contact wheels away. Another thing to keep in mind is vibration. I machined my belt grinder to tighter tolerances then most people are able to when I build mine. Another thing to consider is your grinding skill level. If you don't have the skill to efficiently use a 4500sfpm grinder with the pressure required on a ceramic belt then I would highly recommend you stay away from something faster. Speed does not reduce the amount of needed pressure to make ceramic belts work. But it does strip grit off lightening fast if you don't properly dress your corners befor using a new belt. It's a big safety issue and not something to take lightly. Personally right now I would not have an issue using a faster grinder if I had to but the more I learn the slower I go. It's not about working faster is about working smarter.
 
Tin.Man said:
Natlek your missing something very important. Certain belts prefer that speed, but making a knife your gonna be grinding wood g10 micarta brass aluminum mild steel hardened steel epoxy fiberglass etc. But ask anyone in performance cars or bikes. Faster means more money replacing stuff more often, Subaru station wagon going 300,000 Miles you bet, Subaru wrx souped up? Not likely. You sure your home built tracking and drive wheels are rated at 10000 rpms? What about your bearings?
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I don t think that I m missing anything .For now I have another power tool for grinding wood , micarta ......
I have two wheel grinder only for grinding bevel on knife . I have on that grinder 22cm Aluminium Drive wheel /hole where axle from motor go is steel / And small wheel/made from motorcycle wheel / is 12cm dia. 2Hp motor on 2820 RPM ,so small wheel have only 5170 rpm .I use high quality SKF bearing /C4 / So far no problemo with bearings on 32m/s running belt .I must say that both wheel are perfectly balanced and they are NOT home built . I m almost done with another three grinder .One two wheel again, crazy fast ...over 50m/s .I will use that grinder only for grinding bevel on hardened steel.Next one si almost same as your USA made grinder /like kmg/ on that grinder /three step pulley/ i will grind everything except bevel . And the third grinder is with 17 inch contact wheel on 1400 RPM which is around 31/32 m/s. I try slow speed with ceramic belts and I don t like .......
T Tin.Man .... faster means more money replacing stuff more often.......Bearing a cheap ,what else can wear?
Hey , I m mechanic and I m in performance cars and bikes ;) At eighteen I tune Yugo /1300ccm engine / on over 120 HP ..........
 
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Why In USA they sell you /you build/ belt grinder with THAT two small wheel /2inch dia/ .....because in that size they don t be balanced or what ? I really don t understand that ? They're making a big scary noise , too ? These days I will take short video for you to hear how silent my grinder is at 32m / s .You would not belive ...........
 
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My new Bee tops out at 5400sfm, and I tend to run it wide open for most things. But I also slow it way down a lot of the time.
Don't overlook the other aspects chasing speed... A grinder that's smooth, quiet, and has rock solid tracking will serve you much better than something which puts speed above all else. I can lean into my 2hp bee hard enough to stall it out without the tracking even quivering. That's much more important to me than having an extra 1000 sfm would be.
 
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