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Wishful thinking - wanted 8" 1hp low speed grinder

DavidR8

DavidR8

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Greetings folks, this is a long shot but wondering if anyone has a 8", 1hp low-speed grinder they are looking to sell.
Currently looking at a new Rikon but always prefer to buy used when possible.
 
Depending on what you are doing & how slow is slow, maybe check out Google permutations of Tormek clone/alternative/China. Most are set up with a 2 wheel spindle, grinding on one & stropping on the other. I'm not sure if that means stropping only, or if its standardized you could have 2 wheels?

From what I recall the motors are electrically wound & also have a mechanical reduction to get low RPM. But this is for blades, not sure if that suits your needs. Also the wheels are specific to these machines.

I looked at used Tormeks but they are still spendy at least for what I can justify use. So I break out the hand stones one a month & go into Zen mode for the kitchen knives. But lately seems like word of mouth & FOW (friends of wife) jobs are adding up.
 

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Thanks Peter, I'm looking at it for sharpening wood lathe tools. I'm planning to put on two CBN wheels and use it with my Wolverine setup.
KMS tools has a 1/2hp 8" low-speed on sale for $149.
I've read reports that a 1/2hp grinder struggles to get the CBN wheels up to speed which makes me wonder how long it would last.
 
I may have found a 3/4 solution to my dilemma. Literally.
I was at my KMS store to pick up a 1/2 hp 8" low speed grinder for $149. Turns out they didn't have it in stock. They do have a 3/4 hp 8" low speed for $239. I think I may be able to get that for $200 or so. At 68 lbs it's 9 lbs heavier than the Rikon 1 HP I was looking at so a real beast. I'll pop over tomorrow and get them to run it up for me.
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I thought bench grinders were all about the same rpm ~3000-3500, I guess depending on wheel diameter to get proper SFPM. Do they make models like that 'low rpm'?
 
PeterT said:
I thought bench grinders were all about the same rpm ~3000-3500, I guess depending on wheel diameter to get proper SFPM. Do they make models like that 'low rpm'?
Click to expand...
Yes, this is a low rpm model, turns at 1750 rpm vs 3450.
The low speed is key to sharpening lathe tools without burning the edges.
 
David_R8 said:
Yes, this is a low rpm model, turns at 1750 rpm vs 3450.
Click to expand...
I have that grinder - bought earlier this year. It spins round and round, but otherwise not too impressive. Typical 'offshore' rests and guards which are pretty much in the cheap 'afterthought' category, IMO. Without that special personal relationship with the local KMS that @David_R8 has, I paid full price - close to $300 with tax. It would be an excellent buy at $125. BTW, plate on the motor says 1800 RPM- I was surprised because I'd gotten so accusomed to the 1725/3450 choices.
 
VicHobbyGuy said:
I have that grinder - bought earlier this year. It spins round and round, but otherwise not too impressive. Typical 'offshore' rests and guards which are pretty much in the cheap 'afterthought' category, IMO. Without that special personal relationship with the local KMS that @David_R8 has, I paid full price - close to $300 with tax. It would be an excellent buy at $125. BTW, plate on the motor says 1800 RPM- I was surprised because I'd gotten so accusomed to the 1725/3450 choices.
Click to expand...
Does yours have cast iron wheel guards?
 
Have you considered a belt grinder (2x72), I built my own, doesn't have VFD or run up to the higher speeds as some do, but I never found it lacking.

Haven't touched my regular grinder since.
 
David_R8 said:
Yes, this is a low rpm model, turns at 1750 rpm vs 3450.
The low speed is key to sharpening lathe tools without burning the edges.
Click to expand...
I'm not convinced that an 1800 RPM grinder is really that much 'better' than a 3600 RPM grinder.

Just to be clear, you are planning to use this with woodturning tools, right? High speed steel or (high) carbon steel? AFAIK, it is only with high carbon tools that you need to be worried about overheating and drawing the temper out of the tool. (AKA "blueing the edge".) An 1800 RPM grinder is also perfectly capable of over-heating a carbon steel tool (ask me how I know!).

I believe wheels and technique are more important. For a quick touch-up, the tool shouldn't be on the wheel long enough to get it that hot. Keep a finger up near the cutting edge and you'll know quickly just how hot the steel is getting. ;)

For initial shaping or re-shaping of a carbon steel tool, use a really coarse grinding wheel. Obviously it will remove metal fast...meaning the tool is on the wheel less...and less chance to overheat. Grind and dunk. Grind and dunk. Save the finer wheel for a quick touch-up after the heavy initial shaping.

(Personally, I really like a hard felt wheel charged with green compound for touch-ups. I've never found it a problem w.r.t. rounding over the edge.)

Again, all the overheating concerns only relate to high carbon tools. I have a bunch of antique tools so that can happen and I've done it with both 1800 and 3600 RPM grinders. If the tools are HSS, then this is all a non-issue.

FWIW,

Craig
 
trlvn said:
I'm not convinced that an 1800 RPM grinder is really that much 'better' than a 3600 RPM grinder.

Just to be clear, you are planning to use this with woodturning tools, right? High speed steel or (high) carbon steel? AFAIK, it is only with high carbon tools that you need to be worried about overheating and drawing the temper out of the tool. (AKA "blueing the edge".) An 1800 RPM grinder is also perfectly capable of over-heating a carbon steel tool (ask me how I know!).

I believe wheels and technique are more important. For a quick touch-up, the tool shouldn't be on the wheel long enough to get it that hot. Keep a finger up near the cutting edge and you'll know quickly just how hot the steel is getting. ;)

For initial shaping or re-shaping of a carbon steel tool, use a really coarse grinding wheel. Obviously it will remove metal fast...meaning the tool is on the wheel less...and less chance to overheat. Grind and dunk. Grind and dunk. Save the finer wheel for a quick touch-up after the heavy initial shaping.

(Personally, I really like a hard felt wheel charged with green compound for touch-ups. I've never found it a problem w.r.t. rounding over the edge.)

Again, all the overheating concerns only relate to high carbon tools. I have a bunch of antique tools so that can happen and I've done it with both 1800 and 3600 RPM grinders. If the tools are HSS, then this is all a non-issue.

FWIW,

Craig
Click to expand...
Thanks Craig, it's not the overheating that I'm concerned about, it's the material removal rate. Even with a 120 grit stone on my 6" 3450 rpm grinder the edges disappear very quickly.
I was planning on using a 180 CBN wheel on the 8".
 
David_R8 said:
Thanks Craig, it's not the overheating that I'm concerned about, it's the material removal rate. Even with a 120 grit stone on my 6" 3450 rpm grinder the edges disappear very quickly.
I was planning on using a 180 CBN wheel on the 8".
Click to expand...
How much pressure are you putting on the tool? Is the wheel a good quality one? I got Norton white wheels for the 8" and I can touch up the metal lathe .040" parting blade in pretty controlled way. But those white wheels are soft and I don't think they would last long for 'general grinding' - odd jobs around the shop shaping cold-rolled steel. I kept my 6" grinder for that.
 
One of the good things about that Magnum (KMS) 8" is that the motor isn't too bulky. On my 6", the workpiece starts to hit the motor housing in a lot of situations, especially as the wheels wear down a bit. IMO, a design with longer shafts so that the wheels were farther from the motor would be better on both the 6" and 8" grinders.
 
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