Grinder for lathe cutters

[ttabbal]

So, I want to make bits. I have a harbor freight bench grinder. Not a great tool to be sure, but can it be made usable?

I've seen the threads talking about modifications to a belt sander. That's another option. Any suggestions on what to look for?

 

[darkzero]

Sure you can if that's all you have for now. But it would be best to get some quality grinding stones for it. The majority of bench grinders come stock with crappy stones. That's usually what makes them vibrate like crazy.

I wish HF still sold their tool grinder, they used to only be $130 & with a 20% off coupon you could get it for $104 + tax. Every time I think about it I regret not getting one at the time!

 

[ttabbal]

Thanks for the reply. The HF tool grinder looks like it was a pretty good deal.

My bench grinder does vibrate pretty good, and the stone that HF included is probably just good enough to usually not explode when you turn it on. Can someone recommend a decent brand that doesn't break the bank?

I imagine I would have to freehand it or add a decent rest for the workpiece. The bit of angle iron that appears to just barely qualify as metal isn't very good at staying put.

 

[mikey]

Tell you what I would do. If I was going to use the grinder only for lathe tools, I would consider CBN wheels. Of course, they're expensive. If I was going to use abrasive wheels then I would contact Norton and ask them what wheels they would recommend. I mean, they make em', right? They should know. Wheels are more fragile than most of us think and when we go putting out body weight behind a tool to get it to cut then we are subjecting that wheel to more force than it was intended to take. Better to get the right wheel material in the right grit for the purpose - Norton will know.

On the other hand, a belt sander cuts cooler, faster and flatter. Belts are cheap, do not require dressing and do not blow up (but they can snap if they're old). It takes seconds to change belt grits and you're back to grinding and you can take a tool from shaping to a near mirror finish in under 15 minutes without significantly changing it's shape.

I have ground tools for well over 25 years, on bench grinders and belt sanders. While I am definitely in the minority among hobby guys, I much prefer a belt sander for tool grinding.

 

[ttabbal]

I have ground tools for well over 25 years, on bench grinders and belt sanders. While I am definitely in the minority among hobby guys, I much prefer a belt sander for tool grinding.

I like the look of using a belt sander for this. Do you have suggestions for things to look for in a good tool for the job?

 

[mikey]

I like the look of using a belt sander for this. Do you have suggestions for things to look for in a good tool for the job?

There we have a problem. I have an old Sears 2 X 42, 1/2HP belt sander that works well for me. It is still sold but uses a 1/3HP motor that bogs down sanding wood. If you ever see a 1/2HP version, grab it. Short of a 2 X 72 grinder, it is the best tool grinder I know of. It has a squarish motor housing and looks like this:



A belt sander for tool grinding must have:

• Full and unobstructed access to the right side of the platen. There cannot be ANYTHING in the way; this includes covers or structures or housing or anything. The reason is that the back rake angle on your tool is ground on the right side and edge of the platen so that area must be clear.
• The platen must be removable/replacable and very solidly mounted to the chassis. In use, the platen cannot flex so platens that mount on only on end (like those seen on 1" belt sanders) will not work.
  
• The platen should be very flat and long lasting. I use a piece of O-1 precision ground steel to which I epoxy a ceramic glass (Pyroceram) liner for use as a platen. This platen is attached to an angle iron piece that bolts to the chassis of the grinder. In use, there is zero flex and the glass liner stays flat under heavy grinding for many years.
• You must have a tool rest that is solid and unyielding but is quickly adjustable to precise angles. It should be made of steel so the work piece does not drag or catch. A protractor slot is optional and sometimes useful.

Finding a belt sander that meets these criteria has proven to be difficult. I recently spotted a little Grizzly sander that might work. It uses 25" long belts so I suspect belt life and availability may be an issue but you can see it here:
http://www.grizzly.com/products/Combo-Belt-Sander-Grinder/H7760
http://www.grizzly.com/products/Combo-Belt-Sander-Grinder/H7760
It is a 1/2HP model and you can even mount a 6" wheel on it. I don't know how it will work but with the cover removed, the platen is exposed on the right side. The platen is removable and the work table locking bolt is up front so that a custom table could be built. I don't know what the belt housing is made of but if it is steel then its possible to cut and extend it to accommodate a longer belt. This is the only belt sander I have seen that meets my criteria and I'm waiting to either see a review or if Amazon will carry it so I can get it with free shipping. If I buy it, I'll definitely review it here.

Sorry I don't have better news. If you can afford to build a 2x72 belt sander then that would be ideal.

 

[Rockytime]

I have a HF 6" bench grinder that I use. I use a Norton aluminum oxide wheel along with one of the original wheels. I did make precision washers as well as wheel reducers to replace the loose fitting plastic ones. Vibration is fairly soft now. Most importantly is the tool rest. I use a Veritas tool rest which Is pretty good. I'm 79 sand if I were 10 years younger I would use CBN wheels on a Baldor grinder. If I were 10 years younger I would spring for a new DM 13" lathe. I have sharpened on my HF belt sander but belt changing is a pain and it rattles. Bearings are probably going out, it's very noisy. Mikey has some great advise!

 

[ttabbal]

Thanks for the pics and mentioning the tool rest. It looks like a reasonably priced and functional unit. I might have to pick one up.

 

[Aaron_W]

Mikey, I kept looking around for 2" belt sanders after your comments in my similar post a few weeks back. I found one by Palmgren that looks similar to the Grizzly you found, but uses 2x42 belts instead of 2x27. The small belts was one possible drawback you noted with the Grizzly.

Unfortunately seems to be online only so again not easy to find a physical example to look at. All the photos also appear to be the same stock photo from the left side so not terribly useful for determining how easily it could be made to work for tool sharpening. Unlike the Grizzly the Palmgrens appear to be available, I even saw them listed at Tractor Supply for online purchase.

https://www.amazon.com/Palmgren-Belt-bench-finishing-machine/dp/B0006577HI

 

[mikey]

Yeah, saw that one. It's basically the Sears belt sander under a different brand. It is a 1/3HP grinder and trust me, I can stop the motor dead just grinding wood. I own the 1/3HP Sears model and it will not grind tool steel without bogging down. My old belt sander is 1/2HP and it is vastly superior, although the chassis is the same.