Decontamination 618 Kent surface grinder Y axis Turcite Vee's

[Laurentian]

Hi Guys,

Need some advise as I discovered some wear on our Kent surface grinder we bought new in year 2000. This machine gets cleaned weekly, has hand pump lube and gets taken apart for a deep clean and lube every 5-8 years or so. However a new job came in about 8 years ago and one of our good but sometimes hamfisted machinists likes to run it without the back splash strips in place as they get in the way of a custom fixture. Problem gets compounded when he dresses the wheel ( we never got the overhead dresser for it.. ) and sprays wheel grit all over the place.

Anyhow the back portion of the Y axis V ways are now lightly scored and flaking is long gone. Flaking on the front portion is still present and visible when cranked all way out. I'd like to take the saddle off soon and attempt to clean, brush or even lightly scrape out embedded grit from the lower Turcite Vee and then lightly hand stone the ways, maybe even give them some flaking back to hold oil for now. Would I be harming the machine more than anything or should I just keep cleaning it until I can have the regrind done ? I don't want to move the machine out of it's tight location so if it needs new Turcite I'll have to do it on site to the best of my abilities using the fresh saddle as the pattern and scrape it in.

I have since shown our machinist the damage done and he's taking better care to prevent spraying grit all over the backside. He deflected the issue at first when confronted but I figure it's how he rolls from the other jobs he's had at previous high pressure shops. We're the cleanest place he's worked at but sometimes still needs redirection even after a decade but I do want him around till retirement, so I'm going to repair it and better monitor.

Guess I'm just a little upset at having a machine we bought new get damaged due to carelessness, ignorance and the fact I could maybe have done more. We lost our millwright apprentices when they got hired and it took me awhile to catch up as I do all the maintenance here myself. Anyhow basically just want to make it right again, run well and precisely without having to go full rebuild is all.

PS : It does have the dust collector / coolant unit

As for the Harrison lathe rebuild in my older thread that will be continued in March. We got the bed back from regrind and it has been sitting on the skid with the lathe base, oiled up and covered. Will post when I start assembly.

 

[Richard King]

I am proud of the way you care for your machines. More shops should take lessons from you :-)
How is the accuracy? If the back of the Y axis is worn and you have it apart then sure pull scrape some new oil pockets in the Turcite, no more then .001 to .002 deep and a checkerboard pattern. If you had a straight edge to check the hinge or pivot of the Y ways. If swarf gets in one one end then that could make if high in the middle. I know grit gets stuck in the Turcite, you will want to be careful but if you pill scrape it by holding the hand scraper vertically then pushing it forward. Stoning the surface would be good. By the way my first class I taught in Taiwan, I taught in the Kent Grinder plant is Taichung and Taipei in 1989 and 1090. Maybe one of my students worked on your machine :-)

You may want to hook up a vacuum cleaner to the machine when he dresses he wheel to suck up the grit. Have him lay a thin rubber mat on the back of the saddle too. When you pull it apart please let us see what it looks like. Thanks.

 

[Laurentian]

Hi Richard, thanks for your support it means much to me, I feel better already. Ok will do on pics will dismantle mid month after we ship out some backlog. Ditto on mini vac and rubber sheet off the backside when open air dressing due to the large fixture. Also nice to now about your time at the Kent plant, way cool ! They are a great more affordable copy of the Mitsu grinder.

 

[Richard King]

One of the reasons Kent invited me to teach there as their machines had the reputation of being a "disposable" machine back then. I probably shared this story before, but the new members probably never heard it. Allan Lou the son of the Kent owner back then, since 1989 his Dad has passed away. Allan was educated in the USA - USC I think so he spoke perfect English. He said Japan needed a place to build machine tools so they could charge more for their machines. Back then and even today Japan made some precision machines.

So Japan Machine builders started to build plants in Taiwan and they were sneaky. They didn't show them to scrape properly, They told / them that 10 points per inch and 5% Percentage of contact was the way to go. I have a percentage chart I will try to download so you can see. Well you need at least 40 to 60% or average to 50% contact or high spots to have good scraping.

In my classes I use the example of: You have a 1000 pound table sitting on 2 high spots (points) - so you have 500 pounds on each high spot. (simple math) so all that weight will wear out the points fast compared to having it sitting on 20 points which each point bares 50 pounds . In 1 square inch they way we describe it now or I came up calling it PPI so I didn't have to type so much. lol and POP percentage of points.

I taught at Kent the first week, then Chevalier and another company called Kou Fong who now has a new name. It was the first time in Taiwan machine builders sent competitors technicians to another plant for a class. The builders like Kent were angry how the Japanese taught them. So I suspect if you bought your machine it could have been one of the first machines that were scraped right.

If your not going to replace the Turcite then I would recommend not having the saddle ground as you may change the angle of the V's and you will have to match fit scrape the Turcite thinner. It started out at .047" or .032" thick. Lets talk (write) about that when you get it apart. Thanks for the question as need more scraping posts in here. Rich

 

[Richard King]

Pages out of my work booklet I hand out in my classes. The bottom drawing in the 1st picture shows the disposable scraping PPI as is the first column on the 2nd pic. The 3rd column on picture 2 is the PPI you want to get. I say if you scrape the checkerboard pattern you can get 20 PPI by accident. That's what we scrape for precision machines and 40 PPI is what we scrape for Super Precision machines and inspection tools like straight edges. When I taught at Gallmeyer & Livingston Grinder Co.in Grand Rapids MI, they didn't use Turcite, they scraped iron to iron and only scraped 12 PPI until I showed them how to use a Biax.

 

[Laurentian]

This is great info thanks Richard !

I checked the score marks on the back left Vee that gets most blasted with grit using a joe block as a straight edge and a small LED light. Wasn't able to see any light coming through the little score marks. I did run a wet stone on the last inch of the left Vee facing out during my fussing fit last night and that portion seems to have become smoother to the touch with minimal effort.

The machine was bought new from SMS Machine Tools summer of 2000. Build date October 1997. Hooping we got a good one !

Pics of the Vee's as is onsite will be posted over the weekend.

Thanks for your support !!

 

[Richard King]

1997 was built before my classes. I suspect the Turcite is 100% contact and will get stick slip soon and rip off or loosen the epoxy. A simple trick to see if the Turcite is coming loose is to tap a plastic screw driver handle on the Turcite. Listen for the sound, solid will make a thud noise, loose will make a slapping sound. Better plan on scraping it or replace and scraping it. Bummer.