Surface Plate Resurfacing

[Jake M]

Fair point but precision ground stones are unavailable in the UK. What do you suggest?

In the long term, ground stones are ground on a regular surface grinder. You might stumble on somebody. I'm 82 percent sure that MOST of the cost of ground stones in not the stones or the grinding, but rather the cleanup.......

Having used them, and having ground stones together, I'll second this, and second the recommendation to Robin Renzetti's video. Even if the three stone method got a stone flat, (there's caviats), it doesn't produce the end result. It just creates a flat stone. Which is better than out of the box for sure, but it's not the same thing.

Short of that, if you've got an old file (or get a cheap crappy one), the "Dead File" that Homebrewed described to me is very, very good. It's the same idea. You take the file teeth "flat" on the top, so they can not "dig in" until they hit a raised spot. A "presumably kinda flat but who knows" plate is more than adequate to stick sandpaper on. Glass, a piece of cold drawn metal, preferably not a surface plate until it's proved that it's a condition to warrant this, but really, anything that "seems" flat, and passes a ruler test will make a good dead file. It's cheap, and it's good for "bulk removal" before one would even consider the stones anyhow.

If you happen to stumble on such a thing, (it's a long shot), but "Gauge Block Stones" are exactly this. Smaller in size, but ground so that they can't take material that you didn't want to. Again, it's a long shot, but I know you guys use gauge blocks over there, so "maybe".....

 

[SouthernChap]

In the long term, ground stones are ground on a regular surface grinder. You might stumble on somebody. I'm 82 percent sure that MOST of the cost of ground stones in not the stones or the grinding, but rather the cleanup.......

Having used them, and having ground stones together, I'll second this, and second the recommendation to Robin Renzetti's video. Even if the three stone method got a stone flat, (there's caviats), it doesn't produce the end result. It just creates a flat stone. Which is better than out of the box for sure, but it's not the same thing.

Short of that, if you've got an old file (or get a cheap crappy one), the "Dead File" that Homebrewed described to me is very, very good. It's the same idea. You take the file teeth "flat" on the top, so they can not "dig in" until they hit a raised spot. A "presumably kinda flat but who knows" plate is more than adequate to stick sandpaper on. Glass, a piece of cold drawn metal, preferably not a surface plate until it's proved that it's a condition to warrant this, but really, anything that "seems" flat, and passes a ruler test will make a good dead file. It's cheap, and it's good for "bulk removal" before one would even consider the stones anyhow.

If you happen to stumble on such a thing, (it's a long shot), but "Gauge Block Stones" are exactly this. Smaller in size, but ground so that they can't take material that you didn't want to. Again, it's a long shot, but I know you guys use gauge blocks over there, so "maybe".....

You know, homebrew's 'dead file' post just didn't register but going back and re-reading, it does seem to be the best alternative.

Yep, the UK does have gauge blocks (or 'slip gauges' as they're sometimes known over here); I have a used Mitutoyo set (about a quarter of which are non-Mitutoyo that I've filled in from other brands).

I'll take a look and see what's out there.

 

[durableoreo]

Fair point but precision ground stones are unavailable in the UK. What do you suggest?

Buy a surface grinder and learn how to dress a metal-bond diamond wheel? Honestly, I don't know. Paying too much might be your only option. I promise it's worth it, though. Having these stones available changes the way I approach the work. It's like installing bearings with an arbor press instead of a hammer.

 

[SouthernChap]

Buy a surface grinder and learn how to dress a metal-bond diamond wheel? Honestly, I don't know. Paying too much might be your only option. I promise it's worth it, though. Having these stones available changes the way I approach the work. It's like installing bearings with an arbor press instead of a hammer.

Actually, I don't know if this is worth a try (and for the surface plate, I'll go with the 'dead file' method mentioned above) but there's this video:

What do people think? The stones this chap produced seemed to not abrade or scratch the low spots of the surfaces.

I'm aware using this chap's method won't be to the precision of a surface ground precision flat stone, but given I don't have the money or space for a surface grinder and won't have in the forseeable and also don't yet have the name for my space agency, maybe that's okay?

 

[Jake M]

Actually, I don't know if this is worth a try (and for the surface plate, I'll go with the 'dead file' method mentioned above) but there's this video:

Even if you do end up with the best ground stones in the world..... That file (or pieces of a file broken off to a more convenient size), they will still be your friend. A couple of passes over a "ding" like that one in the video, and it's down to near nothing. Ground stones are SLOW for something that big.

What do people think?

I think the stones in this video don't sound like the ones I have. mine actually came from the place he mentioned.....

What does that mean? I don't know for sure, or even if it's accurate given that his "sound" comes from youtube and mine comes directly measured. His sound "coarser" than mine... Coarser sound. I've got no idea if that translates to the actual grit on the stone, or different stones, or what?
Does that mean anything? Probably. What does it mean? I dunno....

The stones this chap produced seemed to not abrade or scratch the low spots of the surfaces.

Agreed. He got some results. I really can't see or hear or feel that first hand, but they are CLEARLY light years better (for that application) than the stones were in the "as received" condition.

I'm aware using this chap's method won't be to the precision of a surface ground precision flat stone, but given I don't have the money or space for a surface grinder and won't have in the forseeable and also don't yet have the name for my space agency, maybe that's okay?

So think of it like this. If his stones were (not saying they are, but if they were) a little more aggressive, a little less precision, a little less perfect, I'm not sure that they would be "bad" at all. Perhaps they're not suited for surfaces being measured in wavelengths. But if it makes a nice, smooth, useful surface? I've got reservations about the perfection as well, but in practice, what is that going to get you? In my opinion, "perfect" does not exist. So the best description of perfect is something that is perfect enough so that you can consider it perfect, and not be disappointment by that assumption.

You saw the mess spraying everywhere. That's a big commitment to get that mess contained and controlled, as your machine tools and precision things don't want that layer of lapping compound on them, but outside of that? You've got some time in a mandrel, an inexpensive tool, a couple of inexpensive stones (Quality and consistancy of the stones doesn't matter much here), so it's really a very reasonable investment.

Provided you test very, very carefully on some useless pieces first, I can't see any harm from trying, and you "might" get some pretty respectable results. And if you don't get respectable results for surface plates and gauge blocks, you WILL always have other "mid to less precision parts" that could benefit from a stone that's in between a perfect ground stone and a "plain" stone. So I can't see it being a total loss in the worst case.

I think you should let us know how it goes.

 

[SouthernChap]

Even if you do end up with the best ground stones in the world..... That file (or pieces of a file broken off to a more convenient size), they will still be your friend. A couple of passes over a "ding" like that one in the video, and it's down to near nothing. Ground stones are SLOW for something that big.



I think the stones in this video don't sound like the ones I have. mine actually came from the place he mentioned.....

What does that mean? I don't know for sure, or even if it's accurate given that his "sound" comes from youtube and mine comes directly measured. His sound "coarser" than mine... Coarser sound. I've got no idea if that translates to the actual grit on the stone, or different stones, or what?
Does that mean anything? Probably. What does it mean? I dunno....



Agreed. He got some results. I really can't see or hear or feel that first hand, but they are CLEARLY light years better (for that application) than the stones were in the "as received" condition.


So think of it like this. If his stones were (not saying they are, but if they were) a little more aggressive, a little less precision, a little less perfect, I'm not sure that they would be "bad" at all. Perhaps they're not suited for surfaces being measured in wavelengths. But if it makes a nice, smooth, useful surface? I've got reservations about the perfection as well, but in practice, what is that going to get you? In my opinion, "perfect" does not exist. So the best description of perfect is something that is perfect enough so that you can consider it perfect, and not be disappointment by that assumption.

You saw the mess spraying everywhere. That's a big commitment to get that mess contained and controlled, as your machine tools and precision things don't want that layer of lapping compound on them, but outside of that? You've got some time in a mandrel, an inexpensive tool, a couple of inexpensive stones (Quality and consistancy of the stones doesn't matter much here), so it's really a very reasonable investment.

Provided you test very, very carefully on some useless pieces first, I can't see any harm from trying, and you "might" get some pretty respectable results. And if you don't get respectable results for surface plates and gauge blocks, you WILL always have other "mid to less precision parts" that could benefit from a stone that's in between a perfect ground stone and a "plain" stone. So I can't see it being a total loss in the worst case.

I think you should let us know how it goes.

Thank you for such a very well considered reply.

You're spot on about the mess; my lathe and mill are about 3 feet apart, so that's a lot of protection needed whilst trying this.

I think I'll try his method, but later. When I do, I'll post my results.

For now, I'll knock up a 'dead file' for the surface plate.