KO-Lee Cutter/Grinder Revamp

Perhaps you've seen this from other photos... It's a KO-Lee cutter grinder. It's a good platform and the table and all mechanisms are in excellent condition. I don't think this machine was used much in it's lifetime as there are very few signs of wear (hardly any at all really).


The motor is the weak link. The bearings are going bad and vibration can be felt in the short shaft. The long shaft is OK. The seller told me about this when I got it. I'm guessing someone bumped a wheel really hard and damaged the bearing on that side.

Anyhow, I once had a B&S #2 surface grinder but, sold it a few years ago. It needed too much work. It took up too much space, and I rarely worked on parts more than a few inches in size. Also, the things I make do not need sub-ten-thou tolerances. I've used the KO a couple times to do some grinding on small parts within a half-thou and it works out fine. My plan when I sold the B&S was to modify the KO-Lee to handle the simple grinding tasks that come my way.

The time as come...

I'm tackling this in a couple ways and doing the work simultaneously as I go. The plan is to address a travel issue with the KO. It's got about a 12" horizontal travel which stays true the whole way. The vertical travel is about 4" and falls-off at the extremes. I'll see what I can do about that. The other idea, is to remove the old motor and replace it with a small 3 phase and design a new spindle. The spindle design will just be a larger version of the tool post spindle I dreamed-up and posted here several years ago. It's proven to be a very good design but I want to improve a couple things to handle heavier grinding wheels possessing more rotational energy.

This will be an ongoing project that I hope to finish by spring.

The drawing for the spindle is being recreated from the ground up. Here's a sneak preview. The design is still in my head and no dimensions are shown because I'm still making rough measurements of the KO-Lee platform and also, I have not settled on a convenient way to terminate the business end of the grinder shaft. Kicking about 3-4 ideas around. Here's what we have so far. You can upload the .pdf and see it in 3D.


As with the last project (https://www.hobby-machinist.com/threads/bull-nose-live-center.64859/) all the machining shots along the way will be shown and described (so you can butcher-up metal just like me).


Ray C.



What would be wrong with simply replacing the bearings in the original motor?
For the sake of preserving this machine, I'll probably do that too. I'm trying to get a little extra use out of it. The motor shaft is longer on one end than the other but even the long end won't extend far over the centerline, even with the motor fully rotated. That motor attaches with two bolts and sits on a heavy rotating platform attached to a 3.5" dia cast iron pole that can elevate up/down precisely. It's the perfect assembly to make a table-top grinder. The whole frame is about 100 times more rugged than the flimsy 1/2" diameter shafts coming out of the motor.

If you're concerned about preservation of the machine, don't worry; I like old equipment too (as long as it's not totally clapped-out). The motor comes off with two bolts, it will be put in storage with other treasures and a new modular assembly will go on the existing pivot atop the pole.


Ray C.
When this was purchased about 5 years ago, it was disassembled, cleaned and lubed. FWIW, the scraping is about 80% good condition. Since buying, it was only used about a dozen times and only needed to make horizontal (+/- X) passes. In that direction, it stays within a thou until the last inch of travel. I can live with that. In the Y direction, it was varying on a constant slope as the bed was moved toward the front.

I just did a quick disassembly and re-cleaning of the ways and gears. (I'll wipe-down the outside soon. When I was taking it out of storage, a bag of polishing rouge spilled on it....) Anyhow, upon indicating the table, things are looking up. The X direction still looks good and the Y direction can be fixed without modifications.

The arm (I'm pointing to) supports the table and it apparently has a slight slope upward (wrt to the motor pedestal). That arm is totally fixed and the Y ways and gibs are fixed too. The only apparent way to fix the slope is to scrape the ways or bend the arm... I'm not going there. Simple solution... With a sine plate atop the milled circle where the adjustable angle bed sits, I could get the Y direction to run perfectly true with a 1.5 thou shim under the sine leg.

IMG_20180114_153337.jpg IMG_20180114_153423.jpg

I had a hunch this was how things were going to work out. End of story... I'll make a little fixture to hold a small mag vise I happen to have and make sure it's shimmed accordingly. With that shim under the sine plate, the 4" of travel did not move outside of 1 to 2 tenths. I'm good to go. I'll finish cleaning it, build a proper stand (with storage underneath) and continue the motor/spindle module.

Ray C.
It may be a problem to find a replacement motor for the job that is well balanced enough to perform satisfactorily for grinding.
Naaaah... I'll toss a 3 phase on it. Maybe a 1/2 or 3/4 HP. I've got a couple 1HPs around but I'll look for a smaller frame unit.

So here's all the basic parts except the tube/housing in the middle. The ends of the shaft are not designed yet but all the pieces are positioned. A couple things need some minor tweaking after all the components arrive and are measured. The final length needs to be decided upon as well. If you have questions, let me know. Perhaps tomorrow I can post an exploded diagram.

So far, the only significant difference between this and the old post grinder design, is a heavier tensioning spring and beefed-up rear bearings. Those were changed from needle bearings to two radial bearings. For the spring, I'll probably use an automotive cylinder head valve spring.

Once again, the PDF can be uploaded and viewed in 3D.


Ray C.


Made good progress this morning (Oh, how I love having the day off work)...

Here's the first final draft. The parts have been sourced and if this thing works, I'll post all the links to the materials.

With luck, all ABEC-5 bearings were sourced on sale. Taper bearing was $20 and the two radial bearings were $20 each (not bad for ceramic). Two radials were used because the cost of a single wider one, tripled the cost of all the bearings combined. The thrust bearing was $7. Two O-rings were $5. Two oil seals were $5. The automotive valve spring was $6. Total cost is $83.00 and that includes shipping on everything. The metal is all shop drops and it will be a combo of 4140, 1045 -and the tube in the middle (not shown yet) will be aluminum. Automotive transmission fluid will be used for a lubricant. Pretty sure there is a bottle or two in the garage.

There's only one part that refuses to be found easily... A small breather cap with a filter is needed. Just need enough ventilation to let pressure equalize when temps change. -Don't want to suck grinding dust in thru the oil seals. It will get in there over time. Let me know if anyone has leads on a small screw-in, filtered breather element. It can have a tube if needed.

Anyhow, to get good prices, the design was switched to metric bearings. Also, I found (and enclosed) a really handy automotive valve spring ID chart that has full dimensions and compression specs. The compression specs will be needed so a proper shim can be inserted to set the preload on the taper bearing. I've used valve springs for all kinds of stuff and finding this chart was like finding the Rosetta Stone.

Question: To save me some time, does anyone out there have any info about taper bearing pre-load pressures? If you do, let's talk!

The 3D spindle animation and valve chart PDFs are enclosed as attachments.



Ray C


Thanks... While looking into the ones you suggested, these showed-up as a product suggestion and kinda what I had in mind. I might make some kind of hex that covers this and has a cotton/fiber filter too.


Anyhow, I'm going to have some kind of breather and filter element in there because grit inside the spindle is what killed the bearings in my old surface grinder.

Getting a little closer... I think the dimensions are about right except the tapered end needs to be about 1/2 - 3/4" shorter. The taper is a 2 degree so I'll have to make my own hubs for this. The shaft diameter is not large enough to support a standard 3 TPF hub dimension. On the positive side, shallow tapers are easier to cut.


3D PDF also enclosed...

Ray C.


Whoah baby, the bearings and oil seals showed-up today. The only thing I'm waiting on now is the O-rings and the vent plugs but those are not show-stoppers. I mic'd out the bearings to verify size then, plugged the values and tolerances into the CAD (FYI: Alibre). All the bearings were ABEC 5. They mic'd dead-on to spec and feel really nice. What is it about bearings that just seems so cool for some reason?

Friday, I hope to cut most pieces to rough size leaving plenty for the chucks to hold on to. I'm going to heat treat all the metal to RC 38 which is really nice to work with. Not too hard, not too soft, gives nice surface finish that is durable enough for these purposes. The center tube will not be heat treated because it's just a chunk of 2" dia, schedule 80 pipe -not enough carbon in it to bother with. FYI: The diameter of the device was chosen based on sched 80 dimensions.

If all goes well, we'll be in doing lathe work on Saturday. What piece do you want to start with? The choices are: the spindle-end cap, the pulley-end cap or, the spring retainer? (We can't do the shaft or center-tube yet because I'm still deciding on the overall length).

Let me know where you want to start... It's your call. Before we do each piece, I'll post-up the part diagram and profile. We can go step-by-step on how the cuts are executed.


... Didn't get moving on time and am a little behind where I wanted to be. Family matters rule though... The TV cable to the family room went on the blink and I got to spend my Friday night resolving that little issue. Personally, I'd like to cut that cable with snippers but that wouldn't go over very well with everyone else.

The plan is to get all the pieces to rough size then, heat treat the ones that need it. Except for the shaft, all the pieces are trimmed-down.

This is one back-break'n hunk of stock. 4" diameter and about 3' long. Haven't weighed it but, I'll guess it's around 80lbs or so.

I'm not too happy with the current blade in the bandsaw and cutting though a 4" log is taking even longer than expected. All the main pieces were carved off of this. The two end-caps and the two flange plates for the center cylinder piece.

Here's an obligatory action shot... I didn't take pictures while carving things to rough size. I also carved-up some thinner stock -and you'll see why later.
IMG_20180119_181247.jpg IMG_20180120_125631.jpg

And I do believe this accounts for all the basic pieces along with the pieces for a grinding wheel hub. I did my best to size the pieces and orchestrate the assembly steps as not to create a workholding nightmare when the part need to come down to final size. Pretty sure it's all going to work-out w/o too much hassle. You'll see as we get rolling -and if I screwed-up, you'll see that too.

Here's a little hub being made from two pieces. In an earlier post, I misspoke and said it will have a 2degree taper... It's actually 3 degrees and to be specific, it's 3 degrees per side. NOTE: It is not 3" TPF (which is a fairly common hub taper).

The welding Ju-Ju was hit'n on all 8 cylinders today. Yes indeed, this is a gratuitous welding porn photo. It's perfectly fine to ask me what filler wire I used on 1045 -and the answer will be: The piece that happened to be laying on the welding table for the last couple weeks. It was probably 70 or 80S B or D2, possibly 6. Whatever... it will work fine.

So... Hopefully sometime today, I'll fire-up the heat treat oven then, temper these down to about 35 RC which is really nice to work with yet still is a durable surface finish.

Ughhh... ! TIG welding, standing up, working on a round part, elbows up in the air and no hand support. I really didn't want to bother putting the chuck on the welding table so this got welded "cave-man" style. I guess no need for fancy because it's going to be taken down on the lathe. Yes, the weld is recessed a good bit. The outside surfaces of the "donuts" needs to be a precise distance which will be addressed on the lathe; thus, the weld was sunk way below the flat surface of the donut.

Well anyhow, the shaft is 4140 and the donuts are 1045. Do you know what kind of filler rod you're supposed to use with that combination of metal? You guessed it... the rod that's been laying on the table all week. (Turns out it was an ER70S6). I'm sure it will be fine after it's heat treated and tempered. The donuts had to be heated since they were a tight press fit. I'll bring the oven up to 1650 to normalize all the metals. That will remove all stresses, let the metal relax and also allow the weld caps to "meld" with the other base metals. When it drops to 1550, it will get quenched. I have a cylindrical quench tube for just these applications.

And here's the shaft. Currently, it's a good bit longer than it needs to be.

So... those bigger disk-shaped pieces will be welded in similar fashion to a piece of schedule 80 pipe. All the work-holding will be done easily on the lathe. Also, on this project, I'll get a chance to use the bullnose live center that was made not long ago.

I think that's it for now...

Darn Ray, if I knew you were going to do this, I have almost a full complete head assembly less motor from a K O Lee T & C grinder I bought surplus. All you had to do was mount it on top of the round vertical column, add motor and sheaves and belt. The spindle runs smooth, with the mandrel that accepts the common wheel adapters. Oh well. Don't let me stop you from progress. Looking good!
Darn Ray, if I knew you were going to do this, I have almost a full complete head assembly less motor from a K O Lee T & C grinder I bought surplus. All you had to do was mount it on top of the round vertical column, add motor and sheaves and belt. The spindle runs smooth, with the mandrel that accepts the common wheel adapters. Oh well. Don't let me stop you from progress. Looking good!
Thanks Ken but building a spindle like this has been in the back of my mind for a couple years. I pretty-much need to get it out of my system now so, that's what we're going to do. I do appreciate you keeping me in mind though.

And by the way, you know our creed: Never buy something when you can make it for 3 times as much and take 6 times longer to get.

The metal is cooking now. It's all thin sections so this will go quick. Since there's a mix of 1045 and 4140, tempering temps are slightly different. I'm shooting for RC 35. According to the books tempering temperatures for 4140 is about 200F cooler than 1045. I'm going to split the difference and go with an oven temperature of 950. I want the metal to have a durable finish but still be workable. I think we'll be ok...

Good news and bad news. Bad news first. The shaft warped very badly just past one of the donuts. I might try to salvage it by chopping 5" off the end and weld a new piece on. If I go this route it will only be for a learning experience to see if I can pull it off. I've got a bunch of that bar stock around so, a complete re-make is not a problem. If I re-make it, I will bring it and the donuts up to 500F before welding. Also, I'll drill a hole thru the end and pre-string a piece of safety wire thru it. I normally do this so it can be dunked straight in the bath but completely forgot this time around. When it was dunked, it did not go straight into the quench and that probably sealed it's doom.

The good news: All the bearing housings survived the heat treating and as you can see, the impact dent was a good size and even left a crater rim. The 1045 parts came out at RC 33. I took a 5 thou lathe pass over this one before testing it; just enough to skim the scale off. The file grabs it nicely. FWIW, the shaft (made of 4140) tested at 36.


Well... live and learn...

Ray C.
I looked at that bent shaft for 5 minutes and said heck no... It's beyond hope. Just for grins, I tossed it in the lathe and took a skim pass. I was just planning to get a feel for how it cut and see if it produced a nice finish. Look what showed-up... Check-out the hairline crack inside the box.

Aside from that little problem, the finish is smooth as silk.


Part II of Part N (0 < N <= Infinity)

This week beat the daylights out of me but the desire to work on this dragged me out of bed at 4:45 AM to have coffee and get going on it. Several hours later, I actually made it out to the shop :rolleyes:...

Well, this one did not warp as much. I did something called a Marquench (kinda). After pulling from the oven at 1525F, I let it dangle and cool off until the bright red went away then, it was dunked in a brine bath with water that was pretty close to boiling temperature. After that, it was tempered and I settled on 1000F for 1 hour with a natural cool-down. Rockwell came out to 27 and no cracks and very little warpage. In a proper "marquench" the hot part would be dunked in very hot oil for a while then, transferred to a normal quench bath. The concept is to reduce temperature shock.

Turning A Long Shaft:
There is at least a whole book worth of info to be written about turning a long shaft like this. Seems like it should be easy -but many things can go wrong. Often times, a long shaft like this will start to bow as you take cuts. That's a nasty situation and all you can do (that I know of) is use a cathead or, bend the shaft straight. A center rest or follower will do you no good -matter of fact, it will make it worse and probably ruin the piece.

I'm not spinning between centers because I'm using the same trick I showed in another project which is to just grip the end with a couple teeth of the chuck jaws (oh, and how about that sexy look'n 6-jaw chuck?). I put a light shoulder on the end of the shaft so it won't push into the jaws.

The starting point was to carefully make a clean spot in the middle of the shaft for the center rest. Once that was done, the center rest was put into position then, the donuts on either side of center were cleaned-up. Once they were cleaned-up I've been using the donuts to position the center rest when working on the ends of the shaft.

IMG_20180127_075019.jpg IMG_20180127_125344.jpg

Right now, the shaft is cleaned-up. For a while, I suspected the shaft was developing a bow. I backed-off on the center rest legs and used a marker to make sure it printed a circle. There was a very slight bow so, I stopped, had a coffee break then, reseated the shaft in the chuck and tailstock -and for some reason, it went away. -Thank heavens for small favors. I'm pretty sure it was the coffee that did the trick.


Here's some close-ups... Everything is about 2-4 passes away from final size and I'll catch that after sunset. It's a beautiful day outside and the dogs want to take me on my 3rd walk of the day.


Until next time...


Ray C.
So far so good. It's coming out very straight. I'm working right to left and the shaft will remain in the chuck until it's all done.

Here's an in-situ test fit showing the drive side. On the left is the thrust bearing, followed by the spring. The collar that keeps the spring in position is not made yet. There are 2 open bearings (ceramic) because I could not find a longer ABEC 5 (or equivalent) roller bearing at an affordable price. As I recall, these were about $20 each. The shaft gives the two bearings 0.0005" clearance and they glide right on. They can't be an interference fit; if they were, there's no way the spring could exert force to cause the shaft to pre-load the front taper bearing.

When making the final pass, I grew chicken feathers and the final dia came out 0.0013 larger than I called out for. It took about 10 minutes with a wide flat file and some emery cloth to get the bearings to glide on. It still came out like a mirror.


The next thing is to make sure the outside distance between the donuts is exactly 7" as per plan. That's easy. After that comes another critical diameter for the front taper bearing, followed by the taper for grinder hub then, a left hand thread at the tip.

Are we having fun yet?

Finally got to spend some time on this today. Here's the piece that holds the spring. It has two purposes really; one is to support the length of the spring and the other, is to serve as a spacer to enable the spring to exert force on the shaft. The spring constant was provided with the spring and the thickness of that base was designed to put 25lbs force against the shaft (and ultimately against the taper bearing). The base on this "spring sleeve" was made about twice as thick as my calculations called for. I also made the sleeve part a little longer than originally designed. Extra material is OK in this case. It can be fine-tuned when the assembly and testing begins.


Here's some action shots:

I'm really starting to like the new chuck. It's proving to be very repeatable -to the point of initial disbelief when something is first chucked-up. Also, the reason I decided to get it was to put an end to damaging the finish on parts. So far so good.

Since this piece does not need strength, it's made of 1018. As you can see, it basically cuts like warm bubble gum. You can pretty-much spin the daylights out of 1018 and it won't produce a shiny finish.


Once again, when it came time to flip the part, the chuck was holding it darn near dead on. No marks or marring of the piece at all. How nice!


So, tomorrow, I might work on some of the other smaller pieces -possibly the hub -or maybe cut the taper on the shaft. The end caps that house the bearings are too big for a 6" chuck. I have not had time this week to clean up and mount the 8", 6 jaw chuck. I want to use that to make the bearing housings. Sometime soon, I'll switch over to that and will continue my other thread about 6 jaw chucks.

So... sorry about the delays in posting but, it's been one of those knock-down, drag-out weeks.

Coming right along. The drive side shaft and components are done (except for the bearing housing). After a little checking/indicating, the shaft is nice and straight. The testing was not thorough but, at first glance, everything is well within 1/2 thou.


Yeah, yeah, I know... You're probably thinking, "hey, what's that part between the spring and thrust bearing?". Well, I went back to CAD and decided to make a change. The small spacer has a little collar that fits in the ID of the spring to keep the spring aligned. Honestly, with tension on it, I don't think it would drift out of position but, now for sure it won't. I bored the outer spring sleeve a little deeper so there is a zero-net-change in the overall dimensions. Now, when the spring tension needs to be adjusted (downward), we can shave the back of the sleeve or the back of the collar. Right now, the design started with high spring tension and it will be adjusted as needed (by shaving or shimming).

OK, time for breakfast and walk the dogs. -And a cup of coffee (that's been known to cause cancer in California).

Breakfast (and my cancerous California coffee) was good. The dogs had me out there for a long time -making sure I get my exercise.

Coming right along... The 3 degree taper was setup using the shortcut technique described in an earlier project. This does not happen often but, the initial angle was eye-balled into place and when I checked with the indicators, it was so close to dead-on, I was tempted to leave it as-is. Better judgement took over and I bumped it one more time, checked it three times and got the same reading... -Done! No kidding, I've had days were it took almost an hour to get an angle set just right.

The taper came out nicely. If you look closely, I gave myself 1/4" of extra shaft space in case the taper ever gets damaged and needs to get cut back. The boundaries were marked with a shallow groove.

The initial scrape test showed a little low spot.

With a very smooth flat file, the high areas were lightly touched and I'm calling this good.

The fit to the bearing is satisfying... It glides on perfectly up to that point then stops because it's a 0.0003" interference fit.

We'll be done here very soon. Just need to put a left-hand thread on the end then trim the excess.

Because I have not worked on the new chuck, as soon as the shaft is done, I'll start making the wheel hub to fit this odd-ball 3 degree taper.

... Don't be afraid to comment, ask questions or give constructive criticism. This website is all about sharing info and keeping the machining trade alive.

I wanted to be further along by now but, #3 son called, stranded in a local parking lot with a dead battery. We took care of that without issues.

So, it has a left handed tread now and the nut fits just fine.

Threading Quick Tip: If the chuck and leadscrew are rotating in the same direction, you will cut a right hand thread. If the leadscrew and chuck are spinning in opposite directions, it will cut a left hand thread. It makes no difference what directions they are actually spinning, it only matters which direction relative to each-other.

LOL: When I went to cut these threads, I almost made them RH because... well because I just forgot they needed to be LH. Fortunately, I only got as far an initial scratch to see if the pitch was correct. No harm done. Man, I would have been ticked...

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