Thread: An experiment in steel

Mike,
Been following this thread with some interest, Not sure if I've missed something.
Did you do your final grind after heat treat on a bench grinder, if so how how did that go?
Bob Allman tells me it's a real trick to keep the heat down doing it that way.
It's something I gotta do and don't have a belt grinder.

Deckard

Originally Posted by Deckard

Mike,
Been following this thread with some interest, Not sure if I've missed something.
Did you do your final grind after heat treat on a bench grinder, if so how how did that go?
Bob Allman tells me it's a real trick to keep the heat down doing it that way.
It's something I gotta do and don't have a belt grinder.

Deckard

Did you guys see Charlie's post on his hollow grinder here?
Maybe there is a way you can rig your grinder to have a water drip over the wheel (may need a different wheel, but it could work)

Originally Posted by Deckard

Mike,
Been following this thread with some interest, Not sure if I've missed something.
Did you do your final grind after heat treat on a bench grinder, if so how how did that go?
Bob Allman tells me it's a real trick to keep the heat down doing it that way.
It's something I gotta do and don't have a belt grinder.

Deckard

I've been using a bench grinder with a wet paper towel to profile... I just didn't keep the tip cool enough, when it gets thin is when you really have tobecareful
I'm keeping a bucket of ice water next to me to dip the razor in.

Fortunately I only cooked the tip, I can grind away the bad part... If I fried the edge I would have to profile down past it, or start over.

VFD really comes inhandy grinding after heat treat
adn at higher belt grits

Originally Posted by L R Harner

VFD really comes inhandy grinding after heat treat
adn at higher belt grits

I'm waiting for the prices of the VFDs to come down or scoring an old treadmill motor before I can outfit my grinder with one. For now it's step pulleys for me.

Chris L

Thanks for this thread Mike. I have really been enjoying it. I keep coming back to check the progress. I am anxious to see the final product. Your work looks great.





Charlie

I'm no electrician but was wandering if hooking up a dimmer switch into the line might be able to control the wheel speed, I know these grinders can use a no volt switch so they might turn off below a threshold voltage??
I admire the fact the Mike has just had a go and got this far, more guy's should. It don't matter how it turns out it's all learning. Time is a factor but it beats tv (yawn).

I'm sure the time involved would be reduced significantly with better equipment, and it would probably be cleaner work... But so far so good.
I'm learning by leaps and bounds...
I need to find an affordable belt sander that has a good selection of belts/grits...
I remember some threads about them, so when time allows I'm going to have some serious reading to do.
I may go to yard sales and try to find a used treadmill...

Originally Posted by Deckard

I'm no electrician but was wandering if hooking up a dimmer switch into the line might be able to control the wheel speed, I know these grinders can use a no volt switch so they might turn off below a threshold voltage??
I admire the fact the Mike has just had a go and got this far, more guy's should. It don't matter how it turns out it's all learning. Time is a factor but it beats tv (yawn).

To my limited knowledge, it isn't really a good idea for bigger motors like you'd find on grinders or buffers. Rotory tools like a dremel, maybe. The reason I say this is because I was discussing doing this with my father who does electrical engineering and he said it wasn't something he'd consider... I don't have any other info than that.

Originally Posted by Deckard

I'm no electrician but was wandering if hooking up a dimmer switch into the line might be able to control the wheel speed, I know these grinders can use a no volt switch so they might turn off below a threshold voltage??

The main problems are that you lose torque and it eventually becomes more wear and tear on the motor. It'd work if you only did things like this once in a while and weren't stressing the system.

A VFD would be the best solution. Motors are a lot less expensive and you can trick a 3 phase motor into thinking it's getting real 3 phase power and still have the variable speed off a 220 volt single phase line.

The next best solution is what ChrisL is looking for, a DC motor and variable controller. Recycling those is perfect for blades in this size range. You'll lose some of the torque, especially at slow speeds, but you won't burn up motors and electrical stuff as easily.

Keep a water tub handy and dip often. Finishing work like this is best done bare handed. If your fingers are getting hot, it's time to cool the blade. Even then, be careful, steel can feel hot from some induced friction but it still hasn't achieved its maximum temperature due to a lag in heat distribution. You might think you got off the belt/abrasive in time, but the heat in a thicker section might not be too bad there, but as the heat distributes through the thinner sections, it turns out to be too much heat.

Good thread Mike, keep it working.