Surface Grinder Question

From left to right with a know flat precision parallel on top of the mag chuck I got .0004" in two ends and .0008" in the four other ends. Sweeping in the middle, then top then bottom. Mostly the same front to back. I would say definitely concave.
Note: I never went past the chuck (4x6). If i do that readings increase significantly on the ends of travel.

Edit: Another quick question. Is normal for wheels to have some side to side run-out?
 
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The spindle should not have measurable axial (or radial) runout. Wobble in the wheel can be from many factors, including the blotters, the wheel flanges, or a bent or worn spindle or bad bearings. Your machine does not have wheel adapters. Wheels can be dressed on the sides as well as on the face, though it would have to be redone each time the wheel is mounted to run true. Side to side wobble in the wheel is not the end of the world for grinding flat work, but if there are corners, etc., then the wheel needs to be true on the side it is cutting on. All of the above is with the caveat that your SG is different than any I have worked with, so I may be incorrect on some things specific to your machine. I think @chips&more has a Sanford grinder, maybe he will chime in here at some point.
 
Yes he does. I've talked to him about his.
The spindle has no axial runout but .001" radial where the grinding wheel mounts. The wheel flanges are good. I checked with a mic and also on the surface plate. I laid the wheel on a flat surface and it definitely is not true so most if not all is the wheel. This is a Dedeco wheel.
 
Any radial or axial looseness/play in a surface grinder is bad news. Runout is also not good, if over a few tenths. The wheel can be dressed to make it round, but it still does cause some imbalance. It is worth working at getting the spindle to turn as close to perfect as possible -- and critical to have no looseness/play.
 
There is really no play anywhere.
I'm a little disappointed in the runout.
I machined a new spindle for it which I thought would've been less than that.
I pan on keeping this grinder. If I ever learn how to scrape it would be an enjoyable project to make this thing grind flat.
 
Some surface grinders use a belt to move the table at the end of travel it tightens and lifts the table. Plus if you travel to fast it will lift and even skip . I'd mill some blocks and set them up on each corner then grind them one side flip grind and then Ck the sizes if no change try going beyond and back then grind again. This should help rule out if there's a major problem.
 
What do you mean when you say "go beyond then back"?
Mine has a gear and rack. I took the rack off and put the table back on and moved it by hand thinking the rack was interfering. Same results.
The problem with the four block test the magnetic part of the chuck is only about 2" wide.
 
A lot of the errors in surface grinding, as near as I can tell being new to it, are entirely in the operator. Somebody good can make great parts on the same machine that I am making scrap on. All I can say is to pay a LOT of attention to what you are doing, what is happening, and what are the differences between when you get good work and when you get poor work. Some of it does not seem to be all nuts and bolts, but also feel, paying attention to the sounds and the sparks, and trying to figure out what influences which other things.

Here are some things I 'think' I might 'know' about MY surface grinder:
If I run my table fast, it raises up and cuts deeper, probably riding on a wave of way oil.
If I move the table slower, it cuts shallower. (pushes the oil out of the way?)
If it has been some time since properly oiling the machine (hours), the consistency falls off. It improves again when I add more oil to the scores of oilers on the machine.
The vertical travel hand wheel and ways work pretty nice and smooth, but if it does not come down under load with the same constant tactile feedback, and feels light, watch out! It has hung up a bit, and will get even with me later when it finally slides down properly. The cure seems to be lifting it back up and then letting it down to my number until it gives the right feel.
Wheel hop, too much heat in the part, poor surface finish. If I dress the wheel properly and often, and do not cheap out by not dressing enough off, I get much better results.
Wheel selection is also a big issue. If I do not pick an appropriate wheel, I get PPP (**** poor performance). I have enough wheels to pick something close, but laziness bites me in the butt. If I have not studied enough to know what types and grits of wheels do what on what materials, I deserve the surprising results I get.

There is a LOT more of this, but you get the idea...
The good news is that, without a pro grinder hand looking over our shoulder, it is still possible to learn from our mistakes, and I make plenty... We also need to keep tweaking our old grinders little by little until they are reliable and repeatable enough to do good work.

I have worked on several surface grinders, and have the same types of issues on all of them... :(
 
If I was having problems grinding I would make sure I was using an open structure, soft wheel like and H, and grit of 46. In my admittedly limited experience the open structure type wheels which look like swiss cheese, give the waste material a place to go and get out of the way if the the coolant or mist or air doesn't evacuate them. By having a cleaner surface there is less recently cut grit in the way to get ground again. When that grit gets reground it heats, causing local heating of part, further causing part to swell, causing a bigger bite being taken by wheel, causing more heat, on and on. Once that scenario starts and it happens frequently for a novice the downward spiral has begun and its almost impossible to get off that train without stopping , retruing wheel, and making technique changes. As cheap as wheels that don't say Norton on them are, I would make sure I had a 46H in open structure handy. It is my go to wheel for most anything with iron in it, no matter how hard or soft. Learning to grind as Bob and others have pointed out is a process, few people master it quickly. If you are not running flood coolant or a boat load of mist you are making the learning dramatically more difficult. On the rare chance I get to see an old pro grind dry they always seem to have a 46 grit wheel with open structure.

michael
 
Bob Korves said:
A lot of the errors in surface grinding, as near as I can tell being new to it, are entirely in the operator. Somebody good can make great parts on the same machine that I am making scrap on. All I can say is to pay a LOT of attention to what you are doing, what is happening, and what are the differences between when you get good work and when you get poor work. Some of it does not seem to be all nuts and bolts, but also feel, paying attention to the sounds and the sparks, and trying to figure out what influences which other things.

Here are some things I 'think' I might 'know' about MY surface grinder:
If I run my table fast, it raises up and cuts deeper, probably riding on a wave of way oil.
If I move the table slower, it cuts shallower. (pushes the oil out of the way?)
If it has been some time since properly oiling the machine (hours), the consistency falls off. It improves again when I add more oil to the scores of oilers on the machine.
The vertical travel hand wheel and ways work pretty nice and smooth, but if it does not come down under load with the same constant tactile feedback, and feels light, watch out! It has hung up a bit, and will get even with me later when it finally slides down properly. The cure seems to be lifting it back up and then letting it down to my number until it gives the right feel.
Wheel hop, too much heat in the part, poor surface finish. If I dress the wheel properly and often, and do not cheap out by not dressing enough off, I get much better results.
Wheel selection is also a big issue. If I do not pick an appropriate wheel, I get PPP (**** poor performance). I have enough wheels to pick something close, but laziness bites me in the butt. If I have not studied enough to know what types and grits of wheels do what on what materials, I deserve the surprising results I get.

There is a LOT more of this, but you get the idea...
The good news is that, without a pro grinder hand looking over our shoulder, it is still possible to learn from our mistakes, and I make plenty... We also need to keep tweaking our old grinders little by little until they are reliable and repeatable enough to do good work.

I have worked on several surface grinders, and have the same types of issues on all of them... :(
Click to expand...
Knowing how good of condition that grinder was in, I wonder if the table lifting thing is because the way oil is too heavy. I'm thinking a Vactra light might be best, that is what my B&S Micromaster uses for hydraulic and way oil. Generally a coarse grit wheel is best for surface grinding, say 46 grit of a relatively soft bond, Finer grits tend to cause heating and consequent distortion. finish is regulated by the way the wheel is dressed; fast travel, and it opens the wheel up for fast stock removal, slow dress smoothes out the wheel for finer finishes; for very fine finishes, a finer grit wheel may be chosen.
 
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