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Calculating Mount Point Speeds

A thread to identify the correct speeds to run Mount Point grinding tools

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William Harvey 125/02/2022 11:12:30
170 forum posts

Hi,

I have been given a selection of mount point grinding tools, which I am using in a Die Grinder.

I am happy with the grinding speeds for my Carbide Burrs an Aluminium Oxide Mount Points. However I have some pink vitrified bonded corundum stones and I am struggling to work out the correct speeds for these.

According to the guy who gave me them they come from Suhner and the company lists them with maximum surface speed of 45 m/sec.

I have tried to convert this to RPM using this tool here, and get a speed 66110 min-1 (whatever that means)

I am grinding Cast Iron.

Can anyone help?

Les Jones 125/02/2022 12:03:10
2257 forum posts
156 photos

45 m/ sec is 45 x 60 metres per minute = 2700 m/min. One revolution of you grinding wheel is the diameter (D) In metres times π. (π is about 3.142 in case you have forgotten it from when you were at school.)

So the surface speed will π x D x RPM (In metres/min)
So rearranging this RPM = surface speed./(π x D)
So RPM =2700/(π x D)

Les.

Andrew Johnston25/02/2022 12:07:40
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6603 forum posts
701 photos
Posted by William Harvey 1 on 25/02/2022 11:12:30:

...get a speed 66110 min-1 (whatever that means)...

Same as 66110rpm.

Andrew

William Harvey 125/02/2022 12:14:44
170 forum posts
Posted by Les Jones 1 on 25/02/2022 12:03:10:

45 m/ sec is 45 x 60 metres per minute = 2700 m/min. One revolution of you grinding wheel is the diameter (D) In metres times π. (π is about 3.142 in case you have forgotten it from when you were at school.)

So the surface speed will π x D x RPM (In metres/min)
So rearranging this RPM = surface speed./(π x D)
So RPM =2700/(π x D)

Les.

Thanks Les - CSE Grade 1 maths, but my brain has suffered a lot of abuse since then

William Harvey 125/02/2022 12:17:59
170 forum posts
Posted by Andrew Johnston on 25/02/2022 12:07:40:
Posted by William Harvey 1 on 25/02/2022 11:12:30:

...get a speed 66110 min-1 (whatever that means)...

Same as 66110rpm.

Andrew

Thanks Andrew - using Les's formula I get 66176 RPM so looks to be about the same.

So the maximum safe speed for the Corundum Vitrified Mount Points is 66110 RPM, I wonder what the minimum effective speed is? My Die Grinder will only go up to 25000.

"4 speed setting air regulator 8300-25000 RPM, Supplied with 1/8", 1/4" and 6mm collets"

So maybe I can't use them in my grinder?

John P25/02/2022 12:19:14
406 forum posts
257 photos

Google grinding pin speed there are plenty of examples out there
giving wheel diameter to rpm and metres /sec

like this one below

http://www.denchong.com/E/body.php?web=14&PNo=2007110150

John

Andrew Johnston25/02/2022 13:13:02
avatar
6603 forum posts
701 photos
Posted by William Harvey 1 on 25/02/2022 12:17:59:
...will only go up to 25000...

Running at slower speeds makes the wheel appear softer, and therefore it will wear quicker. Practically I expect that running at 25000rpm will be fine.

Andrew

Mike Poole25/02/2022 13:29:15
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Moderator
3343 forum posts
74 photos

An air powered pencil grinder can run at 60,000 rpm and is a useful tool for small mounted points, buying one specially to run some free points rather negates getting a nice freebie. I would use what you have to run them until you have used them up.

Mike

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