[Goldhunter_2]

Ok I know they make a crankshaft grinder lathe but I can't seem to find a old one and new equipment is way out of my price range, I have heard years ago you could buy a crankshaft grinder attachment for the old atlas/craftsman lathes (can't find any of those either)

Here is my question : has any one every made a grinder attachment for say a 6"x36" metal lathe or is it even possible? if you have would you mind sharing some detailed pictures and any plans/draws yo may have so I could try to build my own

[RICHARD ZASTROW]

Goldhunter 2, What size crankshafts? (total swing, off-center throw, length).

There are used crankshaft lathes and grinders on the used machine sites on the internet. Try surplus machine tools etc.

Dick Z

[RFB]

Goldhunter 2,

I have alot of experience with crankshaft grinders and lathes. If you have a lathe then you have approximately 15% of a crankshaft grinder. If you have to ask about the other 85% then you have not done you homework.

RFB

[Goldhunter_2]

Richard,
all the cranks I would mess with are 4 or 6 cyl , 24" or 35" total length strokes are normally 3.87" , 4" , 4.25" witch I figure I need a min of 6" swing for plenty of clearance
I have found several sites or adds for used crankshaft grinders (well out of my budget ) but these are mostly larger machines for more of a commercial application I need something on a smaller scale mite only do two or thee airboat cranks per year I don't care if its a little slower process then is commercial acceptable now either that is why I was thinking of the old atlas attachment I read about but have not even found a picture of one of those yet


RFB,
well your probably right I need to do research that's why I am asking questions , I may be hard headed sometimes but I have learned it is cheaper to ask ahead before lessons get expensive .
seeing one in person would help greatly but unfortunately everywhere around here sends them off so there is no grinders for me to see in person, maybe you could point out where to do my "homework" for small crankshaft grinder attachment

[RICHARD ZASTROW]

Goldhunter 2, Rotating the mass of a crankshaft alone isn't that difficult.

The crankshaft must be off-set equal to the radius of the crank throw to be ground. This is usually accomplished with a set of fixtures. Added to the fixtures are counterweights to off-set the off-set weight of the crankshaft.

The size of the loaded, off-set, counter-weighted fixture generally requires a fairly large swing OVER THE CROSS SLIDE engine lathe.

For limited production, a large swing old HEAVY DUTY lathe with a grinding attachment should be able to fill your requirements. This ASSumes you have the room and available power to hook this up.LOL

Being a bit of a motorhead myself, keep posting.

Dick Z

[Goldhunter_2]

Richard ,
thanks I'll try to post some pictures later when I get it set up , I am selling a miller bobcat to make working floor space for this set up now and other that staying single phase power should be least of my problems ..lol

Robert

[RFB]

Goldhunter_2,

You state that you believe that a lathe with a 6 inch swing would be sufficient. WRONG!

When you grind a rod journal on a crankshaft then the rod journal is running on center while being supported by a steady-rest. That leaves the balance of the crankshaft swinging in an orbit around the rod journal.

In summary, a lawn mower crankshaft rotating on the center line of the rod journal would easily consume a 6 inch swing.

If you wish to continue this persuit then I strongly advise you to locate a used Storm Vulcan or Van Norman crankshaft grinding machine. Be advised that you will have to regrind a heck of lot of crankshafts to justify the expense.

RFB

[RICHARD ZASTROW]

Or subcontract the grinding to an engine shop that has the right equipment.

Dick Z

[Goldhunter_2]

Richard,
subcontracting or sending the cranks of is what I have done in the past but is getting to the point where it would be more beneficial to me personally to set up a small grinder of my own Nothing big like RFB is talking about just to be able to do my own stuff

RFB,
it would be nice if I was able to just right a check for a big used Storm Vulcan or Van Norman crankshaft grinding machine but like I said there just not in the budget nor practical option unless I wanted to open a shop to pay for it witch I don't nor do I have the working floor space to house a machine that size

I may have possible worded my earlier post wrong it would not be the first time my typing did match what I meant ..lol at a 6" swing I mean 6" form the chuck center to the bed of the lathe . I just remeasured a lycoming 540 crank I have laying out here and counting the prop Flange it is under 7" total or form the journal centers to the farthest outer point would be under 5" I believe by what you post says that should be enough clearance

now you have raised another question in my mind I'll explain best I can. you said the crank would have to be centered on the journal and I took that as the grinder wold be fixed ......... I have only been around a grinder once years ago (others have just been shipped off lately) so maybe there are different types but the one I saw and what I was thinking of was more like a old style copier (for lack of better wording ) the crank was center on the mains the grinder would pivot in and out with the journals it had what I would call a following arm like a old key or decoy copier that would keep the grinder wheel rotating around the journal as it turned ......... is what I saw a different type of system then a crankshaft grinder or just a older style? is there a "proper" name for this type of set up ?

[RFB]

Goldhunter_2,

It's become apparent that advice from those wiser than you will not detour you from your thought of using a lathe for a crankshaft grinder. Just for starters, the bearings in the head of your lathe do not have the integrity plus your tailstock is static versus being powered and synchronized with the head.

Wakeup, take a break from your wet dream, go to an engine rebuilding shop and request permission to watch while they setup and grind a crankshaft. If that does not enlighten you then you'll just have to learn the hard way.

The value of the time you spend trying to convert your lathe to a crankshaft grinder plus all of the crankshafts that you will screwup will make the price of a used crankshaft grinder seem very reasonable.

This advice is coming from a person who has many years of experience wih crankshaft reconditioning (Ran grind shop for Swick-Guth, a company that was a Caterpillar certified engine rebuilder (2 cylinder starter engines to D12 engines) prior to Caterpillar doing their own rebuilding) and many more years of lathe experience (Boeing Military Aircraft, CertainTeed plastics tool and die division, Cincinnati Milacron........)

In summary, You're peeing in the breeze and looking like a fool with the pee dripping off of your ears.

RFB

P.S Please post video clips on UTube as you transition through your lathe/crankshaft grinder transformation.

[Goldhunter_2]

RFB,
I never questioned you experience just your attitude . I simplify came on the forum asking for helpful information on a smaller version of something I have seen in the past in a commercial shop , Not your hollyer then then thou attitude That it has to be done the way it is in big shops or not at all . I hnestly don't think you have nor intended any help to my question but rather to show what a ******* you can be
There are lots of things big shops tell you can't be done and are done all the time may of these engine are good examples of that . It wasn't like I was asking for a new patented invention or something but rather looking for more information on a old or I guess you would consider antique style system set up that I had saw before I had more of a interest in it

Oh and as for your pee dripping ears comment mine are dry but you may want to check yours

[Goldhunter_2]

Richard ,
I do thank you for your help to my posted question , there are helpful people out there Thanks

Robert

[deon]

Goldhunter_2

Hi

All this could be done on a lathe type machine. If you do a search for a Prince type crankshaft grinder you should see how. Basically it looks like a lathe with a single headstock and Chuck and a normal tail stock like a lathe. The grinding wheel hooks onto the journal with a finger type setting device and follows the crank big end journal as it turns in the lathe. The grinding wheel is almost like spring loaded as it follows the journal.
I have not personally worked on one before but have seen one in action.
I will see if I can find some more info and then post a link.

Deon

[deon]

Hi

Here the links I have promised.....I found a PDF file with drawings that would be a great resource where you can see the drawings and basic workflow, but it exeeds the file limit of 500kb. As soon as i find a way to post it I will do.
In the meantime have a look at the patent.

http://www.patentstorm.us/patents/6878043.html

Hope this helps.
Thanks
Deon

edit: If memory serves me right the only drawback of the machine was changing the grinding wheel......The whole machine had to be striped!!!.

OK I cant get the file small enough, but here is the link...

http://www.freepatentsonline.com/2475401.pdf

Thanks Deon

[Goldhunter_2]

Deon,
Thanks those are a big help. I just glanced through those and I am going to print them out so I can read them better . The Prince drawings don't look exactly like the one I saw before but very similar and defiantly something more alone the lines of want I can construct for my use. The time issue of changing the wheels out isn't a big issue to me since this is just personal use set up if it takes long to do one that is fine fine with me my mill is the same way it is Old (Moses probably had it on the ark) and it is slow in comparability to new equipment but it gets the job done and like allot of people I can afford to spend more time then money so I'm happy with it

thanks again,
Robert

[RFB]

Goldhunter_2,

Disregard the rest, you win. Please don't forget the UTube videos.

Don't give me this Big Corporation on the back of the little man crap. Big shop, little shop, I have owned an operated both. You ask for input on whether or not it could be done and I offered my opinion based on years of experience, but it did not cheer on your wet dream. One of your more recent responders talked about machine with a chuck so I know he has no actual knowledge because you NEVER grind a crankshaft that is mounted in a chuck, only between centers using drive dogs.

Years ago I raced a Pro Comp alcohol dragster. The blower seized which in turn caused the crank hub key to shear which really screwed up the crank snout. It was an expensive hard chromed crankshaft so I had to rebuild it. I cleaned up the crank snout on our lathe and then used my submerged arc welder to build it back up. I could have turned it to size leaving some excess for polishing with emry paper but I chose to leave .01 for grind and take it down the street to an engine rebuilding shop that had less than a stellar reputation. The job was so simple that I did not think they could get in any trouble, but I was wrong. About an hour after I dropped the crank off they called and said the crank was bent. I went back to their shop and began to examine the crank for evidence of it being dropped because it damn sure was not bent while it was turning in my lathe. No damage but I discovered that they had screwed an extension on the crank snout and then chucked up on the extension which induced a bow into the crankshaft. Ditched the chuck and placed the crank between centers and the problem went away. The shop owner was at least big enough to admit that he had learned something and that they would never again use chucks on their grinder.

There's a multitude of things that I could teach you about grinding crankshafts, but unfortunately you will never need to know about them as long as you continue to persue the 'lathe become crankshaft grinder' idea. I would feel save betting this weeks lunch money that none of the other responders have actually successfully ground a crankshaft. If they claim different then I can ask them one question and their answer will reveal the truth.

You say that I have not offered any advice. I have offered a lot of advice and the best advice was for you to go to an engine shop and request to watch them setup and grind a crankshaft. I do not believe that you would leave their shop with the 'lathe become crankshaft grinder' dream in your mind.

RFB

[deon]

RFB

I am waiting for your question just for the fun. I am the owner of a automotive rebuilding shop and have ample experience of 18 years. I must admit I don't know every thing (not yet anyway) and learn every day.

There is a time and usage for chucking and using centers. The one or the other is not wrong or the only way. All this besides the point. a lathe type machine can be used, that was the question asked and answered in a decent manor without a fight.

I really would like you to explain how a bent crank by means of chucking just simply go's away if its being put between center's. Maybe I just misunderstood you explanation.

Goldhunter_2

The changing of the grinding wheel becomes a big deal when switching between different cranks especially diesel cranks. Most OEM's have there own spec on the corner radius on the journals. Grinding wheels are expensive and redressing to a new radius eats your wheel lifespan. Thats why I keep different wheels with different radii and interchange as necessary.

Regards
Deon

[Goldhunter_2]

Deon,
ok I misunderstood about the changing of wheels I thought you where referring to it being a time issue. the beginning cost of wheels is something I can't avoid but fortunately 90% of the cranks I have to maintain are either 4 or 6 cylinder Continental aircraft engine cranks that are used in a airboat so hopefully I can start with wheels for my continentals witch should all have the same angles and buy others later as needed

thanks for the help
Robert

[deon]

Robert

No pressure.LOL Time and effort is involved........but.............There are ways to overcome this. This was a design flaw in the Prince design.
Keeping this in mind when you do yours you can modify to suite your needs.
Wishing you well in your quest.
Just remember everything is possible to those who really want to overcome the odds.

THIS CAN BE DONE IF YOU REALLY PUT YOUR MIND TO IT!

Best of luck.
Deon

[Goldhunter_2]

thanks