Mitsui 6x12 surface grinder MSG-200MH needs repair

Lost in LA · Jan 4, 2016

Just purchased Mitsui 6x12 MSG-200MH (Mfg date 1994)hand operated surface grinder. It has ball table ways. It was shipped by truck with the balls removed. It seems to be in very good shape with the exception of the longitudinal ball ways on the table. This was expected.

Both the balls and ways are hardened and replaceable.

There are two sets of ball ways (front + back) that are retained by a linear phenolic cage. The balls are 5/8 diameter. The balls have a bit of scuffing and the ways have a witness line that is probably a few tenths deep. The ways also have scuffing both above and below the witness line. I have purchased a new set of balls (about $500 incl tax and license).

I have a couple of thoughts about the ways.

First the way scuffing is all along a fine line at the ball tangent point. Would it be a good idea to take a .6200 gage pin and carefully wrap an abrasive paper (brings it up to .625) of 1500?? grit around it to remove the high spots on the the witness line?

Then install the new balls and see what I have.

Or:
Should I consider purchasing a set of ground factory ways (4 pieces front and rear top and bottom). about $3000.

Or who regrinds Mitsui ways?

Sorry about the bad job of posting pictures!

Thank you,

Lost

Red James · Jan 4, 2016

Clean the ways, do not ruin them with sand paper.

Assemble after cleaning and see how flat it grinds. The ways may be fine, but it is a 20 year old machine with unknown usage. If you are not happy with the flatness then replace the ways.

No one is going to regrind your old ways as true as new ones from Mitsui.

CarbideBob · Jan 4, 2016

Why are you going to mess with this?
Is there a problem with ground parts? If not do not try to "fix" it.
Do not unbolt those ways, You are headed for a world of hurt.
In most cases they work better with a track worn in them. Ball indents are a problem, long straight lines are not.
Ball way grinders typically get better with a few thousand hours on them as everything seats in.
Bob

Lost in LA · Jan 7, 2016

Thank you Red and Bob.

I am in the process of evaluating the machine and all looks very good. The machine came from a tool room and has not been abused.

The ways look ok but it is hard to tell. I have a set of new balls to be installed. But, I would like a way to evaluate the tracks so that new balls are not scared up on the first try.

The angle of the vee is not 45 degrees closer to 55 degrees, which complicates checking.

Thanks,
Lost

Red James · Jan 7, 2016

Both the ways and the balls are very hard (assuming they are replacement balls from Mitsui) and will not be deformed by rolling them down ways that you seem to be leary of.

com4 · Jan 7, 2016

As said above I would just run them instead of trying to sand them down.

ritzblitz · Jan 26, 2016

Just went through this with my 86 Mitsui and my findings are contrary to some of what was said above.

My ways were hammered, i could rock the table with it out at the right side, and I couldnt get the chuck ground in. I also jad issues with chatter at the left rear of the table (read rock). This was because of the huge belly in the rear v way. With an indicator on the table, try to rock it in different positions. I was able to get nearly .002 of rock at the worst point.

Cash at kinetic ground the ways for me. I highly recommend asking him about it. He did a great job. I asked a machine tool rebuilder who does a lot of mitsuis, their orice was 1400 for a regrind. Cash was less, and I would rather support him.

Only remove the ways if you are certain they are negatively affecting the accuracy of the machine. That being said, they are no that hard to reinstall correctly. The big challenge is perpendicularity of the table axis to the spindle axis. Work from the inside out when you bolt them down.

I did not go for the super high accuracy balls, just regular grade 25, IIRC. I cant see a difference in the way the machine grinds. With your machine being fairly new, maybe it is worth throwing the money at it for really nice stuff. They really hold their value. Mine was cheap and fairly worn, so i didnt spring for the high grade balls. At this point I dont regret that decision.

Zahnrad Kopf · Jan 26, 2016

Everything he said, with the addition of possibly looking at oversize/undersize precision balls. I did this when I rebuilt my TP1. Worked beautifully.

cash · Jan 26, 2016

Thanks ritzblitz for the positive comments.

Lost in LA, first it appears you have not run the machine? I would give it a shot first.

If it is not holding size for you then for sure I can grind the ways and then you can replace the balls. If you would like you can sand the ways and that will make then "cosmetically" look good. But if they are worn you will just follow the wear pattern and you will not hold size. Sanding would knock down high spots.

Here are the links to my IG page which shows me grinding ritzblitz, aka chiefbub on IG.

https://www.instagram.com/p/8CQHcJs66d/?taken-by=knifemakerkinetic

https://www.instagram.com/p/7_MFVMM63y/?taken-by=knifemakerkinetic

michiganbuck · Jan 26, 2016

That doesn’t look like much wear so yes you can re assemble it and check it for true in travel length.
We did regrind Cincinnati ball racks for new condition with being careful to take the right amount to keep flat and then shim back to original height. Any decent grind shop can do that job.
Zahanrad’s idea of a larger ball works but yes you may have to open the retainers. 16mm would be about.629 perhaps would work?
We put them together with a coat of spindle oil with not wishing them to collect grit.. Good when you get it together to run a strip if masking tape down the open gap to help keep grit out.

If it was an off brand I would suggest plate checking racks to be sure they were not ground in place.

Lost in LA · Jan 26, 2016

Mitsui cable drive

Thank you guys--You are a life saver.

I am absorbing everyones advice.

I checked the flat way for wear without removing the way. Using a 1-2-3 block with a B&S 1/2 tenth indicator
I could not get any change across the wear mark where the balls ride. Excellent so far. I believe I can assume little wear on the 3 vee ways.

The new ball tracks I purchased all measured the same diameter .6250 As good as my indicating mike could measure.

Have not used the grinder yet. But spindle runs out .0001 at end. And is quiet.

Next issue is the cable drive for the table. Been having trouble wrapping the cable so it stays in the grooves. It wraps around the drum 4 or 5 times but the cable will jump the groove and lay against the adjacent wrap. One of the issues is that the cable is used and it came with several slight humps in it. It is bowed up about 1/16 of an inch for about 2 inches long. We pull the cable taught by hand. Perhaps we need to use weights to keep the tension the same while we work on it.

Is it the hump or is it the technique?

Thanks,
Lost

ritzblitz · Jan 26, 2016

The drive cable is a pain in the ass. I used weights, it also helps to have a second person keeping tension on one end while you wrap. Make sure you have it on correctly, ie not upside down on the drum. I ended up getting it wrapped around the correct amount of times, then wrapping it in the grooves, trying to get the slop out of it. That is where the helper comes in handy. Roll the drum in and out and the cable will eventually seat properly in the grooves.

In case you didnt know, you can line up the orientation of the handle later on, to get it where you like it. It is just a taper fit. Just so you dint get hung up on that.

Fyi, my spindle runs out almost .0003 at the end. Sucks. But it is very quiet when running, as it should be. Check out my instagram, chiefbub. Theres some pictures of my mitsui, before and after and during.

Alex

ritzblitz · Jan 26, 2016

Oh, you can also put a straight edge on the vee ways, and see if you can see light through the wear areas. I could see lots..

Lost in LA · Feb 7, 2016

Ritz-

I got the cable on the drum--What a pain--and properly tensioned.
The table travel is extremely smooth and very sensitive due to the ball ways.

Now, I find out the handle for the longitudinal travel is not balanced--That is a surprise. When the table is stopped (longitudinally) with the handle in any position but down the table drifts to the right or left, depending on the handle location. I taped a 5 ounce weight opposite the handle and that took care of the problem, for now. I might try some automobile tire weights. The table has a longitudinal lock that is very good. I would prefer not to have to lock the table every time I pause .

Any suggestions?

I just discovered "glare gear assemblies" you can find these at William Sopko & Sons Co., Inc - Standard Taper Wheel Adapters
You will need to page down almost to the bottom.

It uses a glare gear nut and a splined key to tighten the wheel hub to the grinding wheel. It gives you a much better feel for tightening the hub to the wheel. I am sure it holds the wheel more securely.

Lost

Red James · Feb 8, 2016

Trust me . . . you want to form the habit of locking that table . . . it moves so easily even sliding parts up to / along the back rail will move the table. Sometimes in directions you don't want. LOCK the table when the traversal handwheel is not in your hand, much safer.

ritzblitz · Feb 9, 2016

Yeah, what red james said. I lock the table most of the time. Especially when im loading something heavy on. As for the unbalanced handle, it never bothered me but balancing it would be pretty cool i think.

michiganbuck · Feb 9, 2016

ritzblitz said:
Yeah, what red james said. I lock the table most of the time. Especially when im loading something heavy on. As for the unbalanced handle, it never bothered me but balancing it would be pretty cool i think.

[the unbalanced handle,] how dumb.. why would they do that?
is it the cross, the long travel, vertical or all.
I could not stand a numbered dial not staying in place... or any handle.

My old cinci #2 has easy very long travel so yes I lock it most often or kick it into fine feed gear. It has a roller at one end so one may put a string (cable) to the table with a weight to draw the work into the wheel under weighted (very light or heavy) pressure.. Never used it but have thought that for slow feed and un supervised cut off that would be the berries. One could even put a micro switch past the cut off travel to turn off machine when cut was done. Could put on a large wheel and cut stone..pudding stone slices are one such item. later cincis do not have that. *Slicing off carbide bars to lengths would be another good use of that feature... you could do that and make some bucks with yours, perhaps using a 1/32 diamond wheel..(+- .001 lengths would be easy.)

Don't know how your drive cable attaches but good to examine and with a die grinder make all edges it might go over very smooth and well rounded.

Qt:
[The new ball tracks I purchased all measured the same diameter .6250 As good as my indicating mike could measure.]

[Have not used the grinder yet. But spindle runs out .0001 at end. And is quiet.]

[runs out .0001 at end] what is that thrust wiggle in and out/ up and down or just indicated run out of the nose? ..*Perhaps just ignore that and see how she grinds..

CarbideBob · Feb 9, 2016

Lost in LA said:
Next issue is the cable drive for the table. Been having trouble wrapping the cable so it stays in the grooves. It wraps around the drum 4 or 5 times but the cable will jump the groove and lay against the adjacent wrap. One of the issues is that the cable is used and it came with several slight humps in it. It is bowed up about 1/16 of an inch for about 2 inches long. We pull the cable taught by hand. Perhaps we need to use weights to keep the tension the same while we work on it.

Is it the hump or is it the technique?

Thanks,
Lost

It may be the hump but on a machine with grooves in the drive hub it is not only important to be on the right groove but also the handle in the correct orient vs the table to get it to track correctly.
Running the table to both ends and looking at where you are on the pulley helps. You can then back of the tension and force the crank against the table stop to center it.
The ends of the cable mounts are offset on the table to make up for the winding on the drum or shaft.
I always tell people to mark the table to saddle and take a picture of the wrap on the drum or shaft and handle position before removal but that's not going to help you now.
Nice that it moves so free. The drift is common and you can't slow down or stop on a dime. You get used to stopping with the handle downwards.
You now know why people who do single pass creep feed grinding absolutely hate ball bearing ways.
Just this side of impossible to work fast with.

Check the cable pulling one way or the other at the extreme ends of travel. This is the only place it is easy to see.
If both are straight or equal and opposite angles your cable needs to be replaced. You may be able to flip it 180 at the fixed mount, rewind and have it work ok.
Bob

michiganbuck · Feb 9, 2016

Cable drive can be improved with a very strong extension spring at one end. I have a machine set up that way so I can travel longer than the rack would allow.. Spring should be perhaps 20 or 30 lb or better for a ball way machine...much like a preload.

PE016-094-8.813-MW-0.250-MH-N-IN

A blade of spring steel could be also used perhaps .04 or .060 x 1/2 to 3/4 wide so cable load bends the spring steel.

Modelman · Feb 9, 2016

I'll second, or third, or fourth the comment about locking the table before you put your hand on the chuck... my Mitsui table will begin to drift from the pressure of my hand wiping grit off the chuck... not good if my hand is moving towards the wheel. Just make a habit of locking it, always, until it becomes second nature.

Dennis

Mitsui 6x12 surface grinder MSG-200MH needs repair

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