Shopsmith Forums

I decided today was a good day to touch up some of my lathe tools on the grinder. (The more I use the Wolverine jigs the more I like it.) Now I normally don't have a pile of chisels that need work but this winter I got lazy and did not keep up with the usage and sharpening very well. I also had a bench chisel that slipped out of my hand and crashed badly that required a bit of adjusting to fix.....

Since I had a selection of chisels each one required a slight to a large amount of different setups. The thing that took the most time was waiting for the grinder to spin down. That was by far the longest part of the whole process.

An electronic brake sure would help in that department but maybe that is impractical due to the mass of the wheels or other issues.

Does this issue come up in your life? Do you do something about it? I guess I'm spoiled after using the shopsmith strip sander set up that doesn't have that issue.

Ed

A 3-phase grinder with an add-on VFD is my first thought. A Google search for 3-phase grinders initially turned up grinders in the $1k range, but there’s a 3/4 hp 8” Dayton grinder at Grainger for $282.

https://www.grainger.com/product/DAYTON ... nder-2LKT1

There are probably similar units for less elsewhere. Adding a 1 hp VFD and a braking resistor would bring the total to somewhere upwards of $500.

Pricy, but easy enough to do. Plus, you’d then have a variable-speed grinder, should that be useful.

At one time I owned an older 12" radial arm saw (can't recall the brand yet) that had a brake that was a smallish lever attached to the guard on the motor side that when pushed, pressed a small brake pad through a hole in the guard and against the side of the blade. Something of that nature would be pretty easy to fabricate.
On a 8" wheel the wheel flange (washer) should be large enough to have room for a pad to run on.


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I forgot to mention above that I would never use an electric brake of any kind on a grinder (or a saw) unless specific provisions were made to prevent the sudden stop of the shaft from spinning the heavy wheel loose and off of the grinder. That's a lot of weight and momentum in that wheel...


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I went out and used a stopwatch to see just how long the spin down time is. The grinder is a variable speed and if I recall right low is 2000 rpm and it goes up to 3400 rpm. I have not actually measured this so it could be off a bit.

From the low speed to a full stop takes 3 minutes and 21 seconds. Some time later I'll see the time from full speed, that I'm guess will be longer.

This is not much of an issue while you are turning as you do the set up then sharpen turn off the grinder and go back to turning.... then when it the tool needs a touch up you go back etc etc. How ever if you change tools then the down time adds up since the adjustments need to be made and it is not safe to be messing about while the grinder is running or spinning down.

Ed

From full speed to stop it takes 4 minutes and 49 seconds.

I also checked the motor tag and the 2000 rpm to 3400 rpm is correct.

Ed

II have never seen one with a brake . I am no authority on them but never heard of such thing, we had one at the shop years ago that would spin 6 or 7 minutes at least after it was shut off , use to take a scrap piece of steel and use it to slow the thing down ,, same with the table saw ,,,use a scrap piece,,, gently ,,, against the ,,,,side,,,, of the blade away from the teeth.