rotary table for grinding

What do you want to grind and how many? I have lots of free time on my Arter rotary grinder.

The necessary speed of the table would be lacking. Further, the table bearing surfaces would be destroyed by swarf and coolant. Not a good idea.
Harold

I have a line on grinding some work for a local company. I have a "standard" surface grinder, but the item in question is larger than the working window of my grinder. A blanchard grinder would be ideal for this. What I have is a grinding head used for grinding the knives on an ag chopper in situ. It essentially is a blanchard grinder, but is not fixtured.
JW

How are the rotary tables on a commercial blanchard made? Looking through the archives, it seems that the contention is that building a blanchard grinder should be a straightforward project for a HSM. What would be the recommendations for a table or swinging the grinder head over the top of the part?
JW

While I've operated a Blanchard, I have never done any maintenance work on one, so I'm not privy to how the ways are located in relation to the table, nor how it is driven. I do, however, have considerable experience with operating grinding machines in general. The one feature they all share in common is that the ways on which they run are always well buried under the surface, so the swarf doesn't come in contact with way surfaces. You can imagine that when running coolant, it would take almost no time to destroy such areas of contact otherwise. I would suggest to you that you could *not* run a Blanchard type machine dry, no way!
There are variations of rotary surface grinders, Blanchard being one of them, Arter being another. They each have a circular table, but the grinding head is distinctly different on each of them. Blanchard grinders use a segmented wheel that is parallel to the table, while an Arter uses a wheel that is at a right angle to the table, the same way a reciprocating surface grinder works. The horsepower requirements of a Blanchard, it stands to reason, would be much higher than for an Arter because the wheel makes contact with much more of the surface being ground. That also means that the grinder would have to be much more robust in construction.
I tend to disagree with you that building a Blanchard type grinder would be in keeping with the ability of the home shop. The necessary rigidity would be difficult to create without castings (cast iron has good damping characteristics, something lacking in steel fabrications, and critical to good grinding results), and the horsepower for anything but the smallest of models would likely be beyond the service available in the typical home shop, especially without three phase. Further, the degree of precision that would be required in order for your grinder to be of any value might be beyond your ability. No reflection on you and your skills, but a reality check in precision work on large items. On the other hand, if you're adept at scraping and have patience, it certainly could be accomplished.
Have you checked ebay for a used grinder?
Harold

never make assumptions about the knowledge or skills of others...
=)
we had a girl working for us, very country (west virginia and texas), 40s
I knew she had done lots of different manufacturing jobs over the years. I was building shelves out of angle iron one day, and joked with her: cindy, are you a a welder?
"yeah"
I asked her what kind of welding she did. she said they never told her what it was. I said, did it look like this, or this? she did production mig welding for a living.
we were trying to help a young engineer develop a cheap, strong valve mount for a construction equipment application. dad recommended a pair of muffler clamps. the young engineer says, what's a muffler clamp? Cindy walked by, picked the clamp up, and said, oh a mufler clamp, I used to make those down south.
You just never know...

It isn't necessarily me you disagree with. In reading past archives, OTHERS have made the contention that a blanchard grinder should be a straightforward project. There are even references to a project sequence in HSM(?)(it may have been PIM). Not having seen one up close, I really have no idea.
I agree, I was trying to figure out how to get the precision required to be useful. Electrical power is not an issue.
JW

Yep, that's why I chose my advice the way I did. I have no way of knowing what the capabilities are of this gentleman, nor what he has at his disposal to accomplish the work. For a successful end result, however, he should have one hell of a lot more than most home shops have available. One thing for sure, though, is that making a rotary table into a grinder is not a good idea, not unless one is willing to make a lot of changes in the basic design. Not impossible, and certainly a starting point if one needs a round table. Just very work intensive. On the order of re-inventing the wheel.
Harold

snip------ I have no idea who these OTHERS might be, but I can't imagine they thought it through very well. At a glance, the machine appears to be quite simple. So does a cutter grinder. Have you ever tried doing any precision grinding with a cutter grinder? I have. Not by choice, however. It was all that was available to me for the project at hand. Did it work? Yes, it did. Did it do a good job? Yes, but only by taxing my very hard earned skills that I acquired working as a precision grinder. In the hands of a novice, I dare say the parts would have been scrapped. These were parts built to mil specs, for a helicopter, a defense job.
My point is that some things look straight forward, easy to accomplish. Things are not always as they appear. I suggest to you that those that think that building a grinder on the order of a Blanchard have likely never seen one. You're not talking about a snag grinder, these things are precision instruments. They use ultra-precision bearings and fine screws in their construction. Yes, you could, too. But can you deal with such components in your facility? Most can not.
I rest my case. Go out of your way to see one, even if only in a picture, then decide if you think you can build something as robust in your facility, and have it do the intended job. My money says it's likely not to happen. Not economically, anyway. That was one of my main points. With a little effort you may come up with a machine that resembles a Blanchard type grinder. What use would it have if it couldn't hold a few tenths? What use would it have if it wasn't rigid enough to take the cuts Blanchards are known to take? What use would it have if it left a poor finish due to chatter? These are all valid concerns. How useful would it be if your intended use is for sharpening a cutting edge? That's not a good design for such use.
One of my acquaintances owns a 48" Blanchard. The wheelhead is powered by a 250 horse motor. His coolant sump is outdoors, more or less an open pit, and he hires a back hoe to clean out the swarf when it's time to change coolant and dispose of the accumulated crud.
Give that some thought when you think you can build a Blanchard type grinder.
That's one point less about which to worry. You're part way there!
Harold

The rotary table is not really built to rotate at the speed nessesary for what you are talking about here. If you could disengage the worm and use some kind of belt drive around the table it might work but again the table is not designed for such work. I have seen projects done with a punch grinding fixture and a faceplate mounted on a grinder to do such a job, but it was only 6" diameter. How large is the part? There are smaller vertical grinders available besides the Blanchard's, Swisher, Springfield and so on. Do a search on vertical grinders
Jeridiah wrote:

I looked it up again. Robert Bastow was primarily the individual to make this claim.
In any case, I have other things to work on now. I will let the idea pass.
JW

"Harold & Susan Vordos" wrote
Ha! Just what I need for my shop..... Harold, you just don't have the right attitude! (g) Just take your Harbor freight angle grinder, and mount it on an arm over your turntable from your stereo system.... voila! A home made Blanchard grinder! Should work fine!
Seriously, I have seen a number of Blachard grinders go for scrap lately. Less than $100. All part of the collapse of our manufacturing economic structure. Easy to find.
Mark