Small sine plate

[steamer]

This sine plate was had as the black sheep of the door prize table at a NEMES annual show about 3 years ago.   Yes...no body wanted the FREE door prize....it was the only thing left on the table at the end of the day.   During the clean up, I inquired as to it's fate, and was told it would be tossed....I said I'd take it....here's how it looked after a good cleaning.








OK....it wasn't flat, and there weren't any rolls....but in general it seemed well enough made.

I decided this would make for a challanging scraping project, so I had at it....scraping steel with a plethora of holes is not easy, but I got there eventually....as flat as my plate anyway.



I then need to make some rolls for it.   Here I cheated a bit and used precision ground stock.  I took two pieces right next to each other on the same bar do the diameters would match as closely as possible.  I then needed mill the V's for distance (5 inches) to scrape the "V"s for parallelism  I have it parallel within .0002-3 range which is pushing my limit of ability to measure.   That'll work



I plan on making some fences for it and using it in my Kurt vice for angled milling set ups.

Dave

[ozzie46]

Well done Deave. I  have read other posts of your scraping adventures. They are very enlightenting. Not sure I want to tackle it yet but it's in the back ground.

  Ron

[Doc]

Very nice looking plate! 

[ironman123]

   Good Job Dave.

Ray

[Bogstandard]

Dave,

I only have the use of sine bars in my small shop, and I am sure you would just love to donate that great one you have made to my little tooling collection.

Joking aside though, that really is a nice piece of kit, and for anyone who doesn't know what they can do, they allow you to set angles exactly, not just close, as you get with the digital angle finders, but spot on, in fact I think they are even more accurate than the precision clinometer I use.

Once only used in the domain of metrology shops, they are being found more and more in the home shop.


Well done mate


John

[steamer]

Thanks for that Bogs!   Here's another picture of the finished plate



Dave

[Bogstandard]

Dave,

I have noticed that over the last few months you have got into this scraping game big time, and I never have, except for many years ago a bit of bearing scraping, which is a slightly different technique, and I have most probably lost the touch by now.

I know that for slideways it is beneficial because of lubricant retention, and some of the ways on my lathe have had basic scraping done, but do you know how they compare to surface grinding for flatness?

John

[steamer]

Hi John,

Well that depends on who's grinding it and on what grinder , and what the base material is.....but

With good grade iron,  grinder and operator who knows what they're doing....flatness in the sub micron region (less than 40 millionths) is quite attainable via grinding, and often far better than that......and generally a good deal faster than scraping.

When I worked for Moore Tool, our hydrostatic ways were ground to tolerances as above for diamond turning lathes.  Hydrostatic ways with axis compensation can tolerate that level of tolerance.

NOW... if your trying to "beat" that....well  Moore tool still scrapes.  You can still buy a completely remanufactured Manual Moore Jig grinder and the ways are done as follows;
The ways are machined accurately.
They are then scraped flat to less than .000020" over any 2 feet of travel.    No that's not a typo.  I've watched Eddie and Brian do it.
Eddie has been at Moore since Dick Moore was at Moore....he scrapes like you and I breathe.....a real master.  I would generally just sit and watch while he worked and told me about his last trip to the casino...
The ways are then hand lapped
The scraped and lapped bare iron now is the way surface for the roller bearings used to support the table.  Amazingly enough, the ways look ground at this point.....but they're not.

OK so what does this have to do with that?


Maybe in 60 years or so I'll be half that good.....but I doubt it.     but

What scraping gives me is a way to hold maybe tenths ....without a surface grinder....which I don't have and have no room for.

Making something that is REALLY flat is pretty easy actually...as long as you have a good reference like a surface plate.

I show these projects to encourage people to stretch a bit and question their machines...and learn a new skill.   It comes in handy.

Hell if I can make something flat ....anybody can!

Dave
 

[Bogstandard]

A little bit too much info for my one brain cell to take in Dave.

But I am sure a lot of other people understood it well enough. I wasn't after proving a point, just general curiosity really.

I gather then my little Herbert surface grinder, with it's plain ways, won't match up to hand scraping then.

Thanks

John

[steamer]

All meant in the spirit of curiosity John

Depends on the grinder John...If I'm scraping it....no....if Eddie is?    Well my money would be on Eddie!

Dave

[swilliams]

Small question about blueing Dave

Do you just place the surface you're trying to scrape on the reference surface or do you rub it? I've always struggled with this.

Steve 

[steamer]

You definitely rub it....but don't push down!   just gently push side to side a half dozen times.

Additionally, I use a water based marking medium which is a bit more friendly to deal with.....

Dave

[arnoldb]

Great going as usual Dave 

I really like your scraping shows; that's something I really have to try myself one day - besides making a couple of sine plates and lathe filing guide and ...

Kind regards, Arnold

[swilliams]

Thanks Dave

Steve