Mitsui 250MH spindle evaluation / rebuild recommendation

[dsatchell]

Hi, I'll looking for a recommendations/experience with getting a Mitsui 250MH spindle rebuilt. I would greatly appreciate insight into a recommended company that folks have worked with. Currently, the quotes I'm getting are 2 to 3k, and generally provide a 1 yr warranty.

as background, we've been using the grinder for about 3 weeks, with good finish and very low noise. While running a large part over the weekend, I started having a ticking sound occur, at the time of the sound, the wheel just nips at the piece, making a very slight rough mar on the surface about 0.2 thou deep. it occurred randomly, and I did not notice much other change while running the part. once i shut off the machine, as the wheel spun down is when I started hearing the additional noise, as the wheel slowed, it was an extra 'tick' sound that slowed as the wheel slowed. Can't really feel any difference as I roll the wheel with my hand. Plan on taking some spindle measurements later today.

Thank you for your help
Don

 

[Richard King]

I see your in IL - There is a company in Rosco IL just north of Rockford and they are a Mitsui and Okamoto Sales and Service dealer. Give them a call and see what they say.

https://www.allworldmachinery.com/services/in-house-repair

 

[Milland]

You might want to make sure you're not dealing with a wheel imbalance issue first, can you run the machine without a wheel and hub to see if still sounds the same?

 

[dsatchell]

Hi, Thank you for the note and recommendations. I'll pull the wheel and check the balance, and spindle noise.

 

[mottrhed]

What did you find? Spindle should look like this, I recommend checking od taper runout, axial play and backlash in the lovejoy. If all those look good Id slide the spindle out and run the motor without the spindle being driven. Let us know what you find.

 

[dsatchell]

Hi, I took all of the info on board, had 0.2 thou runout and significant noise. Colton from Morrall Machine Services came by my shop (thank you!) and took a look as well. I was going to have them do the rebuild on this cartridge but when I pulled the cartridge I found significant staining along the body and a lot of abrasion on the cartridge. Given that, I figured that at least one rebuild had been done at some point. So I was considering other options, and reached out and found that getting a new cartridge made the most sense (it was ~ 2x over a rebuild, and got the new spindle in a day). With the new spindle; very noticeably different, no noise, the hiss of the wheel is the loudest thing that you can hear (and my rotary inverter in the background). I've not gotten the time to actually grind though, later this week with luck I can dress the slide and magnet. I did check the motor, it was quite and vibration free.

 

[Milland]

Any wisdom from the crowd here as to spindle break-in? Worth anything for this application or gas-and-go?

 

[mottrhed]

Glad you got it sorted out. Are you saying the new one was 4-6k? (2x cost of rebuild)

Break in here (talking this spindle-not all) is not super important, and most of these surface grinders are essentially on/off. So starting at 10% or 20% max rpm is virtually not possible. Let it rip!

 

[dsatchell]

Hi, yes that is correct, it was right at 5k for the spindle. I had observed a new spindle start up previously, a few breif on/off's to get it up to speed and then let is run for my standard warmup of ~ 10 min.

 

[Richard King]

On Hobby Machinist forum a friend and student in CA was going to send his Brown & Sharp spindle to a spindle rebuilder and the quote was 4 to 5 grand. I encouraged him to do it himself. and gave him the number of my old foreman who still is rebuilding machinery and he also encouraged him to do it himself. We told him where to buy the bearings how to mount them, use Kluber grease. He did it and he said we saved him $3500.00.

 

[dsatchell]

Hi Richard,
I agree, my first grinder was a 6x12 Powermatic....( I hear the groans already).. it had specific criteria that I needed, namely I could disassemble the grinder and get down a narrow flight of stairs (twice). In any event, the grinder was a mess, after fully scraping and aligning all ways, and new bearings, etc, it worked really well for that level of machine (BTW don't ask how I got the 2x3' surface plate down the stairs (..twice)). Most importantly, it was highly educational. For the Mitsui, I need it for work and just don't have the level of experience to make sure I can set up the spindle and expect half-tenths thou reliability. Other aspects of the Mitsui are in my bailiwick, with lots of reference, help, and applause to information providers on the net.

Thank you again.
Cheers,
don

 

[mottrhed]

On Hobby Machinist forum a friend and student in CA was going to send his Brown & Sharp spindle to a spindle rebuilder and the quote was 4 to 5 grand. I encouraged him to do it himself. and gave him the number of my old foreman who still is rebuilding machinery and he also encouraged him to do it himself. We told him where to buy the bearings how to mount them, use Kluber grease. He did it and he said we saved him $3500.00.

Certainly agree there are projects worth tackling yourself, and some that are not. I think thats one of the biggest challenges when it comes to spindles as you dont always know whats "inside", and many times the issues are not able to be seen by eye.

 

[10 fingers]

I used to repair surface grinders as a field service engineer. Primarily Pope and Whitnon cartridge spindles.. Defective spindles were rebuilt by the manufacturer or, a couple, sophisticated vendors. Touring their labs I gained an appreciation of what's necessary to achieve < ,00005 runout. Not nearly as simple as replacing bearings. Of course, none of that applies if a hobbyist.

 

[michiganbuck]

Any wisdom from the crowd here as to spindle break-in? Worth anything for this application or gas-and-go?

Likely past done, not much one can do on a fixed RPM SG spindle but I always jog start a spindle,
Run it up to about half speed or less, let slow, and then fire up.
If it sets for a week or if left in the cold then give it a hand spin first, and then jog start it.
If it has set for months then give it a number of hand spins before a jog start.

 

[mottrhed]

I used to repair surface grinders as a field service engineer. Primarily Pope and Whitnon cartridge spindles.. Defective spindles were rebuilt by the manufacturer or, a couple, sophisticated vendors. Touring their labs I gained an appreciation of what's necessary to achieve < ,00005 runout. Not nearly as simple as replacing bearings. Of course, none of that applies if a hobbyist.

What do you mean, spindles are a cakewalk, anyone can do it!! Lol

Surface grinders are actually on the easy end of the spectrum, but yes whenever you are in the micron world everything must be right.