I recently set up a used KO Lee S714 surface grinder and was a little disappointed at the finish, though my experience on these tools leaves a lot to be desired. The surface almost seems to have very shallow scallops at regular intervals. They can't be felt by hand and a fingernail doesn't catch anywhere. There is a bit of noise as the grinder winds up but that seems to be coming mostly from the motor. The grinder appears to be in otherwise very good condition.
I checked the spindle runout with a gage head and amplifier and am seeing about 0.00075" with the gage tip on the tapered spindle nose (wheel & collet were puulled off and belts between spindle and motor were removed). I can also get about 0.0015" deflection in the spindle by manually pushing or pulling the spindle toward or away from the gage tip. The spindle feels reasonably cool after running for 45 minutes without a wheel or collet mounted.
This seems to be pretty far out of spec to me, but opinions would be appreciated from those that know better than I.
If this does need attention, is there any chance that the bearings just need adjustment? There's a circular disk threaded into the outboard side of the spindle with holes for a pin spanner wrench. I haven't mucked with that yet but presume that it's there to adjust bearing pre-load.
If the bearings need to be replaced what are the chances of being able to do this myslef? A manual for a slightly different KO Lee grinder suggests that spindles must be returned to the factory for rebuilding.
Hmm ... before we get into the matter of play, I have a some questions to ask:
1) It the motor original?
2) If not, did you replace a three-phase motor with a single-phase motor?
3) If it still has the original three-phase motor -- how are you running it?
a) From genuine power company supplied three phase?
b) From a VFD?
c) From a rotary phase converter?
d) From a static phase converter?
If your answer is either (2) or (3-d), that could be a source of your surface finish problem.
With the spindle warmed up, or after it has been sitting cold for a while?
Is that in the spindle bearings, or in the ways of the vertical slide? (To tell -- shift the gauge to measure the spindle housing and repeat the test.
I think that your measurements may be a bit high -- but the runout (if it is *consistent* runout, and not slop in the bearings) would probably be tuned out when you true your wheel with a diamond. (You *did* true it first, didn't you?)
Then it at least is probably not too tight --but it might be too loose.
Another thing to check is whether the pitch of the scallop matches the teeth of the rack gear on the bottom of the table. If so, then there is proably some slop in the table ways.
It sounds as though it is. I don't know the K.O. Lee grinders, so I would suggest getting a manual to match *your* machine. (Perhaps the company can supply this for you, as I believe that they are still in business.)
I've not tried it. The spindle on my Sanford is still in pretty good shape -- other than the seals. Oil really flows out of the spindle bearings at the stone end.
The manual for the Sanford also suggests that if you try to replace the bearings yourself, instead of sending it to the factory that you are doomed to disappointment. If so, then I am probably eventually doomed, as the factory seems to have folded not long after I got my (very old) grinder.
Hopefully, others will pitch in with their experience, too. When I posted, I saw only your question and no followups.
I suspect that it is a replacement - it's a GE Stock No. K163 (220 VAC,
3-phase) and looks a lot newer than the grinder.
Just a home shop here, with single-phase power, so I bought a new Hitachi L-100 VFD for the grinder.
It was checked both cold and after 45 minutes of running with no discernible difference in the readings.
Hmm - hadn't thought of that. Just cecked, though, and only get 0.0002" deflection when the gauge tip is against the housing.
I'm pretty sure that these readings are not a good sign. KO Lee specs their new grinders at 0.0001" runout. The wheel was trued before taking the test grinds. I believe that I fed the wheel about 5-10 thou into the diamond, a a thou or less per pass, with a couple of passes at the end with no downfeed.. FWIW, the test grind was made with a couple of tenths downfeed per pass, with about 0.050" infeed per pass and it was sparked out at the end.
A friend also suggested that truening the wheel would take out the slop, but it occurss to me that a bad ball or two (needle?) could cause the wheel turn just a little eccentrically under load. I'm wondering if that might cause a slight wheel hop, once per revolution.
I'll check that out after freshly dressing the wheel again but on the sample I have now it appears that the pitch of the scallops is about half the pitch of the rack, maybe less..
Yep, still in business, but they don't seem to have any manuals for this model although they were happy to send me parts manual. That only has about
5 pages with a couple of sectioned views but not much detail on maintenance or adjustments. There's virtually no detail on the spindle or bearings. They did send me a manual for a more recent model (SE612/SE618) but that's been of no help either.
Well, there is always the option of taking it to a machine rebuilder. I know of someone somewhat local and might consider that option. I'd like to be a little more knowledgeable on options before talking to him, though.
The runout seems excessive, .0002 max would be typical for a new grinder spindle, and there should be virtually zero free play, if that's what you mean by "0.0015" deflection". Preload in something like this is not normally adjustable, but is determined by the bearings themselves and the spacers that separate them.
You may be able to replace the bearings yourself if you're careful and educate yourself enough to know when to charge ahead and when ask for help or do a bit more research. As far as returning to KO Lee goes, there are dozens of other spindle rebuilders who will repair virtually any spindle.
Ive got the same issue with my big 6x18. Its the spindle bearings. Shrug..the finish is good enough for my purposes as is the tolerences. When it gets worse, Ill replace em. But Ive seen them go for years and years and not get any worse.
Also be sure to dress your wheel as this can be a cause of that sort of pattern..a somewhat out of balance condition.
You MAY be able to adjust preload a smidge, but then it will reduce the life of your bearings even more.
Ive not rebuilt the spindle of a KO Lee, but they are similar to that of a B&S, and they can be easily rebuilt by the end user.
Btw...if anyone wants a Jones and Shipman surface grinder, Ive got access to two of them, automatic feeds, marvelous condidtion and ready to be put to work, in Santa Ana California
The client wants $1000 and $1500 for them. One is cosmetically prettier than the other, and both are nice.
Gunner
"She's (my daughter) already dating a sex offender. Better that than a republican fundie neocon fascist." FF, (alt.machines.cnc)
I wonder if you have the time to write up a description of rebuilding a surface grinder's spindle, using the example of a Brown and Sharpe machine. I've often heard that a used SG with a spindle that needs rebuilding isn't worth purchasing because of the expense. If it's really not that difficult to rebuild, a "How To" description of the process could open up a new source for used surface grinders, and I'm sure that many people would be grateful.
I think that any dressing without actually removing stone hardens the wheel. Your last pass should remove 1 thou for a 32A type wheel and about 1/2 thou for a NSG blue wheel. Check the Norton web site for tips.
This is Grant Erwin, posting less frequently these days and from Karen's account because my PC is waiting for a new hard drive.
I bought a very used KO Lee S612 and the spindle bearings were bad. I rebuilt my own spindle. The bearings were very expensive. KO Lee specs Torrington/Fafnir bearings but I got New Hampshire Ball Bearings (NHBB) instead. I relied extensively on the internal KO Lee documentation. You should call KO Lee and ask them to speak to someone about how to rebuild your old spindle. My contact was Doug; 605-225-5820 x175. I wrote up the procedure I used, and here it is:
-------------
Spindle:
My spindle is No. S655C, which is real old. I'm told it uses 2 sets of angular contact ball bearings (not tapered) each set of which is Fafnir
2MM9105CRDUME6151. (NOTE: this part number is a K.O. Lee part number from the early 1950's, and it is not possible to obtain this any more for several reasons. The current Fafnir part number is 2MM9105WICRDUM, which is one set. Two sets are needed.)
Removal and Installation:
The bearings are retained by the end caps. The end caps are drilled for face spanners although special tooling may be needed. (I sometimes use two Vise-Grip chain wrenches .. don't know if this will work.) The bearings are supposed to be installed DB (back to back). For an explanation of that, see below.
The bearings are loaded by the lock nuts inside the end caps. In the front, use a very light preload (3-5 inch pounds). In the back, tighten to
3-5 inch pounds and back off 1/8 turn to allow for thermal expansion. After installing new bearings, check runout of the wheel taper. If the runout exceeds .0001" (one tenth) the wheel taper needs to be reground. Note that it may be possible to rotate the bearings in their seats, to reduce runout, as the high runout points are marked with an asterisk on one side.
Balancing is not necessary.
The bearings should be greased prior to use. They should be about
1/3 full only. This should be between 1 gram and 1.25 grams of grease. A suggested grease that is widely available is Chevron SRI. The design of the end caps should keep out coolant and grinding grit.
Addendum (from talking to Jim Goode @ Torrington/Fafnir in Bellevue, also from talking to Doug @ K.O. Lee again)
The bearing number I need is Fafnir 2MM9105WICRDUM, which is a set of 2, I need 2 sets. These should come with the high runout points marked with an asterisk on one side, and with no grease on them. Fafnir recommends that from 1.0 gram to 1.25 grams of grease (they call out Chevron SRI, but others will work) be installed with a finger, spread around the bearing. Fafnir cautions that the orientation of angular contact ball bearings in the spindle is significant. K.O. Lee says that 3 orientations of bearing are possible: DB, DF, or DT, and that DB is called out in this spindle.
An explanation of these last terms is given in the nice URL:
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another good reference site is:
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------- end of my old notes
I went to a "tobacco shop" in Seattle's University District and bought a very inexpensive gram scale to get the correct amount of grease. I installed the grease using a needle attachment to my grease gun (don't remember that part very well). I made a custom face spanner and a lathe-turned bearing drift for this job. My spindle has runout within spec. I have never been able to get a perfect ground finish with it; however I rarely am looking for one. My goal is usually sub-thou parallelism of two flat faces, and this my machine does very well.
I found working with KO Lee to be straightforward and pleasant. I would not hesitate to try rebuilding your spindle. I should note that over the succeeding years I have seen several NOS KO Lee grinding spindle assemblies complete on ebay, and they have often sold for around $100 which is only about 20% of the cost of a new set of bearings.
Any small surface grinder should have the very edges of the wheels eased a little bit with a dressing stone after being trued with a diamond dresser. This helped me a lot to get a much better finish. I also often set a smallish part at an angle to the X travel of the surface grinder, take a pass, then without changing the Z location, reset the part at an opposite angle and regrind. This gives a pleasing checkered finish. It's all cosmetic - even a tenths indicator shows no deflection whatever across the checker marks.
I find that dressing all sides of wheels as well as the working surface cuts out virtually all vibration on any type of mounted grinder. Mine run almost silent and take a very long time to stop after switching off. Mark K.
FWIW, KO Lee suggests that 1 thou downfeed is best when rapid stock removal is desired and lesser downfeeds when one wants to approach a mirror finish.
I wondered if that was the case since the manual I have doesn't mention any adjustments.
I'd be tempted to find someone to do this for me. As it happens, I know someone that owns a machine tool rebuilding company that is not too far from here. He won't be cheap but he is extremely honest and experienced.
Thanks - that's a big help. I wish I had the discipline to write stuff like that down when doing this sort of thing. Sure comes in handy later.
Do you remember the approximate cost of the bearings? Motion Industries has an outlet close by and I'd probably go with them.
My previous contacts with KO Lee were not all that encouraging, but I'll try Doug.
It appears that the end caps will need a non-standard face spanner (odd hole size for the pins), but it should be easy enough to cobble up something up that will work. It sounds like I can remove the end caps without any risk of damaging the spindle or bearings - is that correct? Taking those off would let me check to see if the lock nuts are loose, which would be a step in the right direction.
Good tips in those links as well as the rest of your post.
Good luck on the hard drive - went through a failed HD myself a while back and it wasn't pretty.
My bearings were purchased by the person who sold me the surface grinder who warranted the spindle bearings. I don't know the price, but I expect they were about $400-500.
To make the face spanner I just bandsawed out a flat steel plate into the shape I needed, then drilled undersize and reamed to .0005" under and pressed in a couple of pins. That part wasn't hard. I don't recall the details, but later I found that a 3mm face spanner will work fine in a 1/8" pin application, and that's probably what was called for.
You certainly won't hurt anything by removing the end caps, no. If you carefully count the number of turns when you remove them then you can replace them exactly, maybe. I very much doubt you are going to fix anything by monkeying with the end caps, though. I don't recall any "lock nuts" - on my spindle I remember the end caps being the active member. You'll be shooting in the dark without a good exploded diagram from K.O. Lee, though.
The hard drive failure isn't that big a deal since I do regular backups and since I was able to get all my critical data off it. We have a little LAN at my house, so it was just a matter of getting my stuck disk to spin up again for a short time and copying things furiously until it stuck again. I found that removing the drive and putting it in the freezer (I wrapped it in a paper towel and put it in a new quart ziploc bag so the paper would absorb moisture) for a few hours freed it up again. I would count this as a last-ditch effort only to be done on a drive you're abandoning. It was only a few months old, too. No worry, the warranty replacement is on the way and it will soon be all tight & right again.
Try Alpine Bearing in Boston Mass. They do the mailorder COD thing. Ask for JC. Get a price. MI is often pretty expensive.
"In my humble opinion, the petty carping levied against Bush by the Democrats proves again, it is better to have your eye plucked out by an eagle than to be nibbled to death by ducks." - Norman Liebmann
Careful here. Downfeed is being used in two ways. I was recommending to remove 1 thou at a time when truing the wheel. You are talking about grinding one thou off the work piece.
The point I was trying to make is that how you true the wheel has a significant affect on how it cuts.
About $240/pair from Motion Industries for the bearings Grant mentioned. They show only one pair of the DUM(medium preload) in stock, but over a thousand DUL(light preload). I'm actually surprised that the mediums are specified--I'd expect a light preload in a grinder spindle.
If you have a chance and feel so inclined would you take a look at this site:
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I've uploaded some pics there along with a brief description of what has been done and observed so far. It's a bit rambling and not especially well organized.
I'm especially interested to find out if the spindle bearings appear to be the proper type, or at least the one that I could get a picture of. I found an old 1985 Fafnir catalog that provides some info on the 2MM9105WICRDUM bearings that you referred to in an earlier post and these look similar but I'm not sure about the reddish brown part of the bearing. Is that the (CR) composition cage, which is apparently non-metallic? I'd also be curious to hear what folks think of the finish on O-1 steel.
If this were my spindle and I didn't need to have it running tomorrow, this is what I'd do. Disassemble it, take careful note of how it's built and make sure you understand why. Take lots of photos in case you need to ask questions. Make sure to keep the paired bearings together thru the whole process.
Wash the bearings thoroughly, inspect them carefully under a stereo microscope for any obvious damage or wear to the balls and races. Assuming they aren't obviously NFG, give them a final rinse in clean acetone and regrease.
Reassemble the spindle. If they're identical, switch the two pairs of bearings, back pair to the nose. The bearings at the nose likely take more abuse than the back pair and have more effect on the runout.
Worst case, the spindle will be no better than when you started, but you'll have learned something and had a practice run rebuilding the thing without jeopardizing an expensive set of new bearings. If you've lived a clean life and help old ladies cross the street, the runout may be improved.
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