KO-Lee Cutter/Grinder Revamp

[ddickey]

Answer #2: The motor... I called the distributor and they recommended a test to let it run for a while. They were willing to accept a return if it was not satisfactory after break-in. I decided to let it run in 30 minute intervals for 4 or 5 hours. The heat problem resolved itself and is due to the fresh rubber oil seals breaking in. The vibration also smoothed out to an acceptable level but, I'm still planning to take it apart to see if I can balance the rotor a little better.
Ray

I had this problem when I rebuilt the spindle of my surface grinder. I bought the correct size oil seal but the shaft heated up tremendously. I don't remember the exact temp but you could not touch it for more than a split second. I didn't know you had to break them in. I ended up taking the seal off and using a V-ring (shaft mounted rotary seal).

 

[Downunder Bob]

G'day ray, an excellent post on a great build, I don't know where you get the time.

BTW what lathe is that? I'm guessing it's a PM 1236 from a few clues. The bits I can see of it, it looks very similar to mine LD1216, although mine has a much shorter bed, a case on necessity, I don't enough room for a longer one. But it's a nice machine I'm quite happy with it so far.

 

[extropic]

Thanks 'extropic', I appreciate all the Likes you gave. FWIW, many years ago, I had more Likes than posts but back in 2012 or 2013, we got hit with destructive virus and my post count and Likes got erased.

Answer #1: To check the shaft, I coated it with bluing and used the long edge of a HSS tool blank to scrape the high spots. I checked the tool blank on a grade A table and verified it to be flat. The taper technique is also shown in this build thread: https://www.hobby-machinist.com/threads/bull-nose-live-center.64859/

Answer #2: The motor... I called the distributor and they recommended a test to let it run for a while. They were willing to accept a return if it was not satisfactory after break-in. I decided to let it run in 30 minute intervals for 4 or 5 hours. The heat problem resolved itself and is due to the fresh rubber oil seals breaking in. The vibration also smoothed out to an acceptable level but, I'm still planning to take it apart to see if I can balance the rotor a little better.

Gratuitous BS: FYI: The project is still on hold until while my shop is being reorganized. I need to build a table for that grinder and I'm not inclined to do welding until the weather improves where I can do it outside. Also, the metal frame/box needs to be sandblasted and painted -which I don't do until the garage is opened up.

Ray

What's not to like?
Thanks for clarifying those points Ray.

A couple more questions please.
I'm wondering what your thinking was regarding not setting the 'standard' 3"/12" arbor taper as a design requirement? In other words, you set some other design feature(s) as higher priority than the 'standard' taper and I'm wondering which/why?
I guess intended wheel size would be a key factor. What max wheel diameter do you intend?

I'm 'watching' the thread now so I'll be patiently awaiting the completion. Great project. Thanks for posting.

 

[Ray C]

What's not to like?
Thanks for clarifying those points Ray.

A couple more questions please.
I'm wondering what your thinking was regarding not setting the 'standard' 3"/12" arbor taper as a design requirement? In other words, you set some other design feature(s) as higher priority than the 'standard' taper and I'm wondering which/why?
I guess intended wheel size would be a key factor. What max wheel diameter do you intend?

I'm 'watching' the thread now so I'll be patiently awaiting the completion. Great project. Thanks for posting.

My pleasure... Ask all the questions you want...

The shaft is too narrow (about 7/8") for the standard taper. I want to use 1" hole diameter grinding wheels and to get any appreciable surface area on the taper, the shaft would need to taper from 7/8" down to about 1/4". I wanted the small OD of the taper to be 1/2" because I had a few 1/2" LH nuts around to use on this project. Also, with 1 HP at work, I want more than a 1/4" nut holding the wheel on.

As it turns out, I abandoned the tapered shaft idea and went with a 2-point tapered wedge setup. It works great and eliminates all the other problems at the price of a little extra machine work.

Decent grinding wheels with 1" ID and 6" OD are plentiful and cheap. As soon as you need to buy wheels with larger ID holes, the price jumps 500%.

Ray.

 

[Ray C]

Just a quick heads-up that this project is now resurrected. I moved the last of the shop tables around and made another table for this grinder and some other grinding devices.

Today, I had some left-over paint that my wife gave me and used it on the housing parts. Not exactly a good color match to the dark grey base of the KO Lee but... oh well... It will have to do. This should be dry by tonight and I'll start re-assembly this weekend. I'll also make a wheel cover and will show pics as it progresses.



Ray

 

[Ray C]

Here's the new home for the KO Lee.


Everything prior to this point was purely experimental and I was ready to toss it in the scrap pile if the results were not acceptable. It seems this "conversion" will work-out. I'm re-making some of the parts for the motor bracket. Still getting it all put back together and waiting for the paint to dry on a couple small brackets that I forgot to paint yesterday.

Right now, making the wheel safety cover. Making this up as I go and don't really know what it will look like until it's done. Time for lunch and dog walk. Probably will lay in the sun for a while and get some vitamin D.



Ray

 

[Ray C]

Didn't have much time today but got this put back together




Here's piece from the scrap pile that I remember hardening but forgot now what it was for. Anyhow, it's RC 37 so I put it in the lathe for a face cut then, did a quick grinding test to make sure everything was still working OK.

I'm quite pleased. The whole setup is running quite nicely. Probably hard to see in the pictures above but some rubber pads were put between the motor plate and the motor brackets. It sounds nice and smooth and feels very smooth too.

The wheel is a A80 5" so it's pretty unforgiving. Dressed the wheel and did a test. It's a keeper. When I went into this project, I was thinking it had maybe 70% odds working-out ok. Well, we made it!




Here's the safety cover so far. I'm going to build a vacuum tube receptacle into it.


This should be finished-up in a day or so.

Ray

 

[Ray C]

Doing some fine-tuning on the hub mechanism which, so far, is working-out really well. From the onset, I knew a thin spindle shaft was going to cause problems. I truthfully though this setup of centering the hub on flexible wedge rings was going to go up in smoke and blow this whole project. In an act of desperation, I concocted that mechanism and am pleased with it now.

I've taken the whole wheel and hub off several times and using an old crappy drop-indicator on the outside of the wheel, it re-installs with TIR that appears to be less than 1 thou. I'll make a few more hubs for other wheels.





A couple spanner holes on the front facing locking plate are still needed. Of course, everything is left-handed threads -thus, painting the nut red so it does not get mixed-up with others.


For anyone who may be new to surface grinders, buffer pads on both sides of the wheel is a highly recommended safety procedure. At high rotational speed, a wheel can oscillate. If the wheel is pressed directly against the metal hub, the vibration can (under really extreme conditions) cause the wheel to fracture. The pads absorb the vibration and also have more gripping friction than smooth metal. All around good thing to do. I cut buffer pads out of thin cardboard.



Ray

 

[rwm]

I am confused about your hub mechanism. Do those wedge rings create force pushing out on the ID of the wheel? If so, is that safe? I always thought wheels had to be gripped in compression by the flange/washer.
Robert

 

[Ray C]

I am confused about your hub mechanism. Do those wedge rings create force pushing out on the ID of the wheel? If so, is that safe? I always thought wheels had to be gripped in compression by the flange/washer.
Robert

The hub is solid and is no different than any other hub as far as how the wheel attaches to it. There are wedge rings on the spindle shaft that self-center the hub to the shaft. Check-out the thread at the link.

Ray