New Centerless Owner! What am I getting into?

[Machinery_E]

Bought a Cincinnati "LL" centerless (#2) Working on getting it going, the hydraulic pump has a leak on it. Was being used, and had it demoed, they sold it since they no longer had the work for it. This is quite a machine, and I'm really excited about getting it going!

How much stock can you take off in a through feed setup? The manual doesn't really say. Would .010 be too much? How about plunge, is also .010 doable? Thinking here is finishing turned parts.

What about safety, any tips on loading the work for both through feed and infeed ops? Guys I got it off could not stress enough that it was the most dangerous machine in the shop.

Thanks!

Eric

 

[garandguy]

The amount removed depends on wheel and feed method. In through feed I wouldn't remove more than .0005" at a time. On plunge you could eventually feed to .010 removal, but it is not a rapid process (kind of like rmoving .010 on a surface grinder). Centerless grinding can be a volume grinding process, but it is not one for removing lots of material because like other grinding techniques it will burn the parts.

Find someone that knows how to set up the wheel cant for feed through. Make sure you have a good support blade, with a good work edge angle. Your feed rack to the support blade is not critical. These machines are not very prone to experimentation. They aren't the most dangerous in a shop but they can be unforgiving. If you need help email me at [email protected] just call me garandguy.

 

[JHOLLAND1]

40 years ago Cincinnati Milacron released a safety film on centerless grinding. They took a 40 hp grinder, placed a small explosive charge between arbor and active wheel, brought it up to speed and activated the charge which was just enough to fracture a 12" by 24 " wheel. Well, slow motion footage showed a 14,000 lb grinder pretty much air-borne. The headstock left the machine. I fired up my no 2 cincinnati only once and then parted it out. I still have 2 small instrument type centerless european machines but low hp.
I have tried to obtain this 16mm video including contacting Milacron.. no luck.

jh

 

[Lost in LA]

That is a hefty machine. I have some smaller ones and regulary plunge grind 1/2 dia x 2 inch long removing .005 in about 20 seconds--no problem holding .0001-.0002. You can probably do better.

Thru grinding I can remove .003 to .004/pass on stock in the 3/8 to 5/8 dia range. You can do lots better.

Get advice from someone with experience with your size machine.
Lost

 

[Gary E]

Others have said it, I will repeat... GET an EXPERT to SHOW you how to use this machine.

I dont mean to scare you, I worked at Cincinnati and not only ran those grinders, I helped build them, and installed them in the customers plants...

Centerless grinding is not rocket science, it's just grinding, and yes you can take a lot more off of a part than anyone has mentioned... I'll give you one example, I know of one plant that makes pipe, and runs the intire 10 in dia x 20 ft long pipe into one end of the centerless and out the other end comes a finished pipe... Diameter reduction of aprox 0.100 in ONE PASS.
Dont try that unless YOU KNOW WHAT YOUR DOING.

The Centerless is just at home making small very precision parts, think very small, the smallest we did was a 0.0025 dia wire aprox 3 ft long... You ask what was used for a work rest blade?... sure... We used a hacksaw frame holding a 0.002 feeler gage.

Infeed is also a method... again, PAY someone to show you how, or hire someone that has the experience.

 

[Machinery_E]

Thanks guys! The problem with getting someone in here is that where I am its a rather rural location and finding people with this sort of knowledge is hard. That is great news that it is possible to do some pretty serious grinding-this is the first grinder I've owned that has an ammeter.

Eric

 

[huntinguy]

the first thing we tell apprentices when they run the centerless is: count your finger when you start and then make sure you have the same number when you are done! At least I think it is a joke.

I was through feeding aluminum spacers (like rings .75 wide 2. in diameter). One part cocked and emptied the grinder. I can tell you that we found one part about 70 feet away.

the centerless is a great workhorse... It is no place for armatures. Find someone and pay them to come out and teach you.

 

[tdmidget]

Gary E is right. I ran centerless for a couple of years and they are amazing . They can also cripple and kill you. A small part can be cocked by a chip and turn into a bullet.
First, I cannot emphasize this too much, GET A MANUAL for your machine. Even if you don't understand all of it at least you will know what to call stuff. If I was close by I would help you get it going. I haven't run that particular model but the principles are the same.
Work safely

 

[Gary E]

Thanks guys! The problem with getting someone in here is that where I am its a rather rural location and finding people with this sort of knowledge is hard. That is great news that it is possible to do some pretty serious grinding-this is the first grinder I've owned that has an ammeter.

Eric

I did not know where Richmond is, and I grew up in Ohio, so I looked it up... yeah, your out in the sticks... and that presents a big problem. But I'm going to again strongly sugest you get some training on this machine from a EXPERT or go get a job in a Centerless Shop for 6 months, yes SIX months MINIMUM, or... SELL the dam thing before it kills you.

Sucessfull outcome of a centerless is dependent on the SETUP... and that takes skill that can not be learned from a book, even if that book is availabe... Let me give you a example... You have NEVER seen a machine shop, and the only power tool you have ever seen is a hand held electric drill motor with a 1" spade drill in it to poke holes in wood, but you have NEVER even held that sort of drill. Now you walk into a machine shop with a huge radial drill and are told to drill a 3 inch dia hole in a steel plate. Where do you start?, how do you start?... remember, YOU KNOW NOTHING... nothing about where to start... Now even if you find some book somewhere that lets you figger out how fast to run the drill and it all goes to hell in a hurry, you do have a stop button on that radial that will stop the spindle within a short period of time.. There's NO SUCH STOPPING a GRINDING WHEEL that is 20 inches in Dia going 60 miles per hour in any time soon enough to avoid a very serious injury to you.

If you could find EVERY Centerless Shop you can in Pittsburg, Columbus, Cleveland, Akron, and ask who they know that retired not long ago, maybe, just maybe you'l find a qualified guy. Then you going to have to convince him to move to Richmond for 6 months and stay in a motel, and teach you, you might learn enough to go on your own from there on...

Are you willing to spend that much to learn ?... if not, just sell the machine.

And then there's the work for it... Do you have the work for it?.. are you sending Centerless work out now? and want to bring it in house?...

 

[Machinery_E]

That's pretty scary the thought of parts going airborne! The previous owner is a cool guy, but he had no experience either and it was more a cut and try way of learning. With the work rest setup on it now, for example, I was told that they didn't know if it was right or not but it worked for them.

I've got all the manuals for it.

I understand the thing about work going where its not supposed to-like not having a good hold on surface grinding parts. What happens is so fast that by the time you hit the stop button its over!

Its upcoming work I have in mind for it-like now filing and polishing long slender parts on manual lathe...if I could run 'em through the centerless, take .010" off them to clean them up, in fraction of the time compared to the hand polishing-that would be downright awesome! Other little stuff that may also start going is in mind for it.

So no, unfortunately I don't have 100K of work waiting for it. Budget is limited. I can't afford to hire someone now.

Good idea on trying to talk to grinding shops in the area, though I haven't had much success trying to work with other shops, even though most of the work is our own products, people can have the mindset of if we're not doing it, why help?

Eric

 

[Mebfab]

You would have been better off with a centerless belt grinder. Lot less explosive. Ow the belt hit me, vs the snow shovel being used to scoop you up.

MIght have one of the belt sanders for sale

 

[Machinery_E]

May very well be true Mebfab, thing of it is, "have been". Already almost got killed/seriously hurt hauling and rigging this puppy in. I'm too far in now to stop...

Eric

 

[steel hand]

We went through a similar process years ago. Brought a part in house we had been sending out. Thousands of parts per year, aluminum tubes ranging from 10" to 3' long. We bought a rebuilt #3 Cincinnati. The seller set up the machine for what we wanted to do. We sent a employee to their location for a week to learn how to run it. Since then we have done many other parts we previously sent out, but all through feed parts. We don't do in feed grinding. If you are thinking that you can do a wide variety of jobs with one machine, you may be in for a surprise. Our machine was originally set up to do aluminum tubing in the 1.8-2.0 diameter range. That's still the majority of the parts we run on it. We now do other jobs such as steel pins down to about 3/8, but had to buy another guide bar to do that. We don't have the best wheel for ultra fine finishes on steel, but we get away with it. A good grinding shop may have 2 or 3 centerless grinders, which they use for different kinds of jobs.

Good luck, and get some training. This place rebuilds grinders and offers training.

Allways Precision, Inc.

 

[Croz]

You WILL need some expert tuition if you have no experience with centerless grinders. I used to work on Cincinatti twingrips on thru feed grinding brake caliper pistons, wheel cylinders and damper rods. I also worked on a big old 3EA and 220 and 2OM on plunge feed camshafts, and truck brake (drum) tappet adjusters. Back in 1981 the company i worked for bought a Lidkoping centerless for thru grinding damper rods and that beast broke a wheel, i thought we were being nuked!! the machine lept of the floor and the wheel fragments hit the factory roof! there was grit and damper rods everywhere and one ashen faced 19 year old apprentice, who only 5 minutes before was trying, with a stick of caborundrum, trying to take out a damaged corner of the grinding wheel after he tried to change the machine to grind a smaller diameter. And he did all this unsupervised! needless to say he had a right old bollocking of the boss. I still have all my old centerless grining tech books although i have not had to work on centerless grinders for the last 6 years. Nowadays all the grinding i do is cylindrical, surface and cutter grinding, but centerless? awesome machines and nothing will "round" a diameter like a centerless!
Croz

 

[learner54]

I'm a newbie to this site so forgive any lack of protocal. I'm looking for advice on type / grade of centerless grinding wheel to rough and finish aluminum tubing. The finish isn't that fussy 16-32 so I'm thinking an open grain (46?) resin bond vs. vertified (?) wheel. Does anybody have any thoughts on this?
Thanks in advance
Learner54

 

[Gary E]

I'm a newbie to this site so forgive any lack of protocal. I'm looking for advice on type / grade of centerless grinding wheel to rough and finish aluminum tubing. The finish isn't that fussy 16-32 so I'm thinking an open grain (46?) resin bond vs. vertified (?) wheel. Does anybody have any thoughts on this?
Thanks in advance
Learner54

It's been far to long ago for me to remember anything along that track... so..
CALL the GRINDING WHEEL Manufacturer you plan to buy from,
THEY know what wheel to use.