A grinder for HSS toolbits

[schwabw]

Harold,

Excellent write up as usual Harold!
Victor

Seconded!! I hope this gets integrated with the archive of your other posts on grinding. Let me the be the first to request an updated copy.

With the little free hand grinding I've done, I quickly found you were right about it being easy to do (and a big deal to master). Part of me still wonders about the bit "flying away," temporarily wedging itself in some case/rest/wheel gap, and then turning into a projectile. It might take a group of mistakes to let that happen though.

I can't wait to get into the thread on chip breakers. THANKS!!!!!

Bill

[Black_Moons]

If you have one fixed flange, I think the other would just tilt as needed. Usally theres a fixed 'step' in the grinder shaft that one flange rests apon.

bench grinder is definately on my project list too.. so many ideas..
So far my favorate is making a 5C 1"~ collet holder to a reverseable bench grinder motor (3600rpm~) and then making arbors for my wheels, precision made on my lathe and clamped perminately to the wheel so that I don't need to true them after swaping wheels or try and replace them 20 times to get everything aligned. Basicly a quick change grinding/wirebrush/polishing wheel system. And maybe some kinda reasonabley quick wheel guard removal and table style change...
Probley have 2 of these setups, one for traditional radial grinding wheels, and another for face/cup/cone grinding wheels like toolroom grinders use.

I wish I had some kinda information about what bearings to use to hold the grinder shaft...

PS: I think iv figured out why most plastic bushings are 'loose', its because when you clamp the wheel from the side, it will shift the alignment of the wheel, if the bushing was tight, it would snap the wheel. I think the solution is buy proper 1 peice bushing as the multi peice ones I don't think are gonna hold accurately enough. also don't reuse em, they seem to have ridges along the side to allow deformation of the plastic when the wheel shifts on clamping, so they get deformed/worn on the first use. Alternately, or maybe even better, make your own custom perfict customised to bench grinder shaft bushing that goes to say, 1", then use the 1" to 1 1/4" plastic bushing only (and machine to fit its interiour perfictly)

[EdK]

I found a 6", 3450RPM grinder hidden in the basement I forgot I had. It was made in 1991 and made in Taiwan. It's only 1/4HP so I was wondering if this grinder has enough HP to be worth setting it up with 7" x 1/2" surface grinding wheels per Harold's instructions? The 8" grinder I was going to convert is a 1750RPM grinder which isn't ideal so I thought maybe the 6" grinder might be a better candidate.

Thanks,
Ed

[Harold_V]

The vast majority of the work you'll perform at the wheel requires almost no hp---aside from roughing a blank. As long as you use the proper wheel and keep it dressed (free cutting), you will likely get by just fine. That's not to suggest that a half horse wouldn't be better---it would be.

Be certain to make larger shrouds for the wheels, to insure that if you lose one it doesn't take you out in the process.

Harold

[EdK]

Thanks Harold.

I wouldn't even consider using the grinder without the proper shrouds so I will be sure to make and install them prior to turning on the grinder. I'm going to go ahead and convert the 1/4HP grinder and also keep my eyes open for a good deal on a 1/2HP.

Ed

[EdK]

I checked my motor which has a wire brush and deburring wheel on it and it's 1/2HP @ 3450RPM. I just assumed it was 1/4HP so didn't even consider it as a candidate for the surface grinder wheel modification. It was made in China so I'm not sure how trustworthy the HP rating is but I'm going to go ahead and use it for the modification anyway.

Thanks again Harold for your excellent write-up on this modification.

Ed

[EdK]

I'm in the process of designing the adapter for my grinder and have a question. The shaft on the grinder has a smooth 1/2" diameter section and a sloppy 12mm threaded section. I was wondering if I can cut off the 12mm section and just use the smooth 1/2" section for attaching the adapter to? The 1/2" diameter section is about 1" long and the 12mm is about 3/4" long. See pictures.

Thanks.
Ed

[GlennW]

Why not just make a split adaptor with a 1 1/4" shoulder to locate the wheel that pilots on the 1/2" shaft, and use the existing 12mm nut to secure the wheel/adaptor to the shaft?

[EdK]

Why not just make a split adaptor with a 1 1/4" shoulder to locate the wheel that pilots on the 1/2" shaft, and use the existing 12mm nut to secure the wheel/adaptor to the shaft?

Glenn,

Please excuse my ignorance, but what is a split adapter? I was following Harold's proven design and did not want to "reinvent the wheel" but I'm certainly open to an adapter that is easier to make and will work with my grinder shaft. Are you talking about something like in the attached drawing? The "split" in your comment is what's throwing me off.

Thanks,
Ed

Edit: updated drawing.

[GlennW]

Yes, that is pretty much what I was thinking. That along with another large disc to sandwich the wheel.

I was actualy thinking just two discs with a 1 1/4" shoulder on each disc to locate the wheel.

Keep the wheel as close to the grinder shaft bearing as possible.

[Harold_V]

I certainly agree with Glenn on this particular adaptation. I made mine as I did because the shaft on the motor I use had no threads. In your case, assuming the existing shaft is straight, you won't have need for the six tapped holes, so, over all, your design is much more convenient.

While it doesn't show in the picture, my concern would be if the wheel is too close to the motor that you can't get at the side of the wheel, and that the motor isn't so large in diameter that it interferes with a tool when using the periphery of the wheel. If neither of them is a problem, you should be good to go!

Harold

[EdK]

OK, thanks guys. I think I get the idea now.

Harold,

These two pictures should answer your two concerns about the grinder. It appears the grinder will work out quite well. The motor diameter is about 5 1/2" and there seems to be more than enough clearance from the motor to where the grinding wheel will be to get at the sides. I plan on putting an 80 grit on one side and a 46 grit on the other end of the shaft. After I get the adapters and flanges done I'll tackle the wheel guards.

Thanks for all of the help.

Ed