Improvised tool post grinder

[lametec]

Needed to clean up some welds on the ID of a pulley. Boring bars were no good due to lots of interrupted cuts.

The pulley started out life like this. The ID was too small, and there's no setscrew on this type of pulley:

So it was bored then welded to one of these on the ID and OD:

This left the ID undersized and "messy", so I improvised a tool post grinder using a dremel type tool and a pair of locking welding pliers (I forget where I got 'em.. I think HF).

The best solution would of course have been to have used a 1-7/8" ID pulley to begin with, but I couldn't find one at a reasonable price. The pulley and collar were $14 from surpluscenter.

Anyway, I clamped the tool to a boring bar and went to work. Worked just great!

Not a precision grinder for sure, but all I needed to do was grind the ID to fit a 1-7/8" motor shaft. It was a perfect snug fit when I was done.

 

[bimmer1980]

I like it! a good get 'r' done solution.......

If you were going to do a lot of tool post grinding, I suppose an air die grinder and a nice mount would go along ways..... that's a thought I will have to remember when I get my Lathe hooked up and running.....

 

[srmofo]

hose clamps work awesome when you need to hold stuff like that too.

 

[Torque1st]

Another example of Yankee ingenuity and "sweat equity".

 

[Ign]

I had the exact same thought when I bought my first HF electric die grinder and it said it was for tool post grinding. I think something was lost in the translation, but it got me to thinking about building a mount for it.

I think you could do something really nice by boring a hole in some Al for the grinder to fit into, and then secure it in some fashion (honestly I was looking at the 4 screws which hold the neck of the die grinder to the body). Then adapt it to a tool block, or cut dovetails and have a dedicated tool block.

 

[wreckercologist]

I've seen this done in a machine shop I used to work in. Not as good as the real thing, but it gets the job done.

 

[lametec]

I think you could do something really nice by boring a hole in some Al for the grinder to fit into, and then secure it in some fashion.....

You mean like this:

You take the front "collar" off the dremel, then screw it into this adapter. Then clamp the other end of the adapter in a tool holder.

About $17 from here.

 

[Ign]

You mean like this:

Maybe, but you're restricted solely to the length and rigidity of your tool. I guess that's good for drilling holes, but not for cleaning up ID's of bores. The long shaft of the HF grinder would allow much more reach into bores, again assuming anchoring at the point where the neck meets the plastic body

http://www.harborfreight.com/electric-die-grinder-with-long-shaft-44141.html

However the HF grinder is not variable speed, and most dremels are.....

 

[cnc-me]

I hate to say it, but your hub is probably going to crack loose from
the cast iron pulley.
Also aren't you worried about the grinding dust getting into the lathes ways.

Just some observations,not trying to be a smart *** here.

 

[lametec]

I've already had a similar pulley/collar combination on the RPC for a while now. Only difference was pulley diameter. No issues. It was something I considered, but hasn't proven to be an issue. And if it does crack, well, no big deal. I made a belt/pulley guard for the RPC, so it's not going anywhere.

If was doing a lot of grinding, yes, I'd worry about it. This was the first and only time I used the grinder so far. I made sure to clean off the ways once I was done.

 

[cnc-me]

I've already had a similar pulley/collar combination on the RPC for a while now. Only difference was pulley diameter. No issues. It was something I considered, but hasn't proven to be an issue. And if it does crack, well, no big deal. I made a belt/pulley guard for the RPC, so it's not going anywhere.

If was doing a lot of grinding, yes, I'd worry about it. This was the first and only time I used the grinder so far. I made sure to clean off the ways once I was done.

Are you using a small single phase motor to start your RPC?

 

[lametec]

Yep. 2HP pony winding up a 20HP idler.

When I first built it I used 4.75" pony pulley and a 4.45" idler pulley so the idler would be overspun a bit (about 100rpm) on startup, thereby limiting the inrush current as much as possible. Well, this seemed great in theory, but as it turns out, the unloaded speed of the idler is exactly the same as the pony, so I changed the idler pulley to a 4.75" as well. Inrush is now shorter, causing less of a brownout.

 

[Steve from Socal]

I know you mentioned it before but, in the future ANY time you use abrasives near a machine PLEASE cover the machine ways. It only takes a few grains of abrasive to start some very bad wear.

Steve

 

[cnc-me]

Yep. 2HP pony winding up a 20HP idler.

When I first built it I used 4.75" pony pulley and a 4.45" idler pulley so the idler would be overspun a bit (about 100rpm) on startup, thereby limiting the inrush current as much as possible. Well, this seemed great in theory, but as it turns out, the unloaded speed of the idler is exactly the same as the pony, so I changed the idler pulley to a 4.75" as well. Inrush is now shorter, causing less of a brownout.

Ever try start capacitors instead of the pony motor.
I built a converter last year, for a guy that wanted to run a 20HP wide belt
sander. Used a 30 HP idler with start caps, started right up,
with only 100 amp single phase service.
(well, actually 2/3 of a 100 amp 3 phase service, I have line power 3 phase.)
Used about 1800 micro farads of start caps, with 600 micro farads of run caps. Seemed to run the sander quite well under load.
Might be going off on a tangent for this thread.

 

[lametec]

I didn't even consider start caps for this size idler. The brown out is bad enough when I switch on the idler now (with it already up to speed).

Occasionally I've switched on the idler before it's up to speed (adjusting the timer), the lights in the garage go to probably 20% and the idler growls for a few seconds before reaching it's idle rpm. Not sure this one is a candidate for cap start.

Besides, I already have the pony setup working, so why reinvent the wheel, you know.

 

[Scooterzs]

A GOOD machinist knows after a job is done, the machine( lathe, Mill, etc.) gets a good cleaning