# Surface plates & hand scraping - should I or shouldn't I?



## Highpower

Heres the thing....
I want to start doing some hand scraping. Lets just say that funds are not real plentiful right now.  
You need a good flat reference for laying out a film of spotting dye to mark the surface of the part that you want to scrape.
OK, fine. I have a nice Starrett "Crystal Pink" surface plate that I use for measuring and layout work that I can spread the dye onto. So nice that I am having a hard time thinking about covering it with permanent blue stains all over it.

So the question is: Do I just suck it up and use what I have, or do I try to scrounge up enough cash for an additional cheap, *cheap* import surface plate to use for spotting? Keep in mind that shipping costs on these things are almost double the cost of the surface plate itself.  

What would YOU do?


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## Highpower

My concern is that I've read about _other_ people spreading the blue ink/dye on their surface plate (pink granite) and having ugly permanent stains on the plate even after the ink/dye is cleaned off. If I had a piece of *black* granite I wouldn't really care because it would not stand out. Knowing that there is a foreign body (a stain) on my purty pink rock would just bug me. Probably much ado about nothing, but that's the way I roll. lol.

Just wanted to know what other folks might think about it.  

Edit to add:

Sorry Jerry. I went back and re-read my original post and saw where it wasn't really clear as to what I was wanting to do what with what.
I have re-worded the original so hopefully it makes more sense now.


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## Highpower

DaveH said:


> Willie,
> 
> If the surface is being used to try to wear down the high points - then that is a different story.   I've seen it done!
> 
> DaveH


No Dave, that is a different *tool* not a different story.  

"Alex..... What is a _lapping_ plate?"  I'll take world geography for $500.....


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## Tony Wells

A good exercise, with beneficial products at the end, that will give you good tools for checking flatness is to make your own straightedges. Here's a good writeup of how to do it.

http://home.comcast.net/~jaswensen/machines/straight_edge/straight_edge.html


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## Joe in Oz

After just having finished a rwo day scraping course, may I briefly say that ther is a bit of misinformation in this thread already.
The spotting blue or bearing blue is indeed applied to the granite or other surface plate. the object to be scraped is then very lightly rubbed a shrt distance on the blued stone. The high spots on the workpiece are then scraped down - a process which removes a few 10ths of thous with effort and fractions of tenths done gently.
The process is repeated until the entire workpiece surface is covered with lots of densely spaced small bearing spots - higher spots that the valleys in between. Accuracies better than 1/10000" are possible.
That's the VERY short version.
The blue which is applied to the reference surface plate is earily removed completely. It is NOT permanent. There are both water and white spirits or methanol soluable dies. This stuff is NOT engineers' or layout blue!
A search on "metal scraping" will give a lot more detail. That's the process your granite surface plate was made for, incidentally.
Cheers,
Joe


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## Highpower

Yes, this video shows the general idea of the operation. And I understand that the dye used (in my case) is not permanent (indelible ink) in and of itself.
However - I have seen where other people who also own the Starrett pink surface plates have stated that the hi-spot blues get into the micro-cracks or pores in those plates, and aren't removed after cleaning and remain visible. Much like getting a water stain in a granite kitchen counter top that hasn't been sealed. The stained area stays dark and looks like Fido's butt IMO.  

Apparently from what I have read in the past, it is not a problem with the Starrett *black* surface plates. Something to do with the "crystal" content in the pink plates I _think_?  

I sure wish there was a class available around here.


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## Tony Wells

The "crystal" in granite plates is quartz. There is more of it in the pink plates, with the Starrett "Crystal Pink" plates having the highest concentration of it. That's what gives the plates their long life and hence high cost.

I use a black plate, and although they need lapping more often than the pinks, I'm not too hard on it, so don't worry so much about that. Just keep it clean and avoid sliding stuff around on it and it will last years and years. I've had several plates in an inspection area, both pink and black. Everyone wanted to use the pink, naturally, so it had to be lapped yearly. The blacks, although not used as much, wore even more. Some had to be lapped by 0.002-0.003 to restore flatness to just grade b. We kept the pinks at grade A.

I'd not use my plate for a scraping project. If I had to, I'd buy a small one for the project, then give it away, since they aren't expensive.


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## brucer

anytime i've seen someone scraping a machine they used hardened precision ground bars for bluing, pretty much like large gauge blocks..   seen one guy use a large starrett level one time. 

only bluing i've ever done myself was bluing seal offs on cores and cavities.


 any hi-spot blue i've used will stain pretty much anything, except for the water soluble hi-spot, it takes some getting use too but its cleaner to work with..


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## Highpower

Well I'm not looking to do scraping on machine ways, just some smaller sized individual parts.
Since I don't own a surface grinder it would be nice to be able to flatten some surfaces on things like small engine parts, warped manifolds etc., and other general use.
I may have a line on a cheap black surface plate, but it's looking like it's in the _too good to be true_ category right now. I'll make some phone calls tomorrow and see.  

Update:
As I expected, Enco (*once again*) prints the wrong information in their sale catalog. (November "HOTdeals".) No black surface plate for me. I guess that answers my own poll question for me. Meh.

A cast iron plate is definitely out of the picture for me though. 
Demasiado dinero!


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## Highpower

Dave,
For what it cost me originally, not especially.  

And the thought of dragging parts around on it and having to get it lapped again later, also not too appealing.
An additional "inexpensive" plate would suit me fine, but the money tree growing in my back yard died a few years ago I'm sad to say.  
<wink,wink - nudge, nudge>


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## Tony Wells

Well Dave, since we're mentioning substitutes, I would be remiss if I didn't mention that one of my early employers started his shop with a _tombstone_ for a surface plate. They can be polished granite, you know.

I've often wondered if the guys who come cert and lap would accommodate that, or would they tell you to get lost.


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## Tony Wells

Jerry, it would have the curvature of the earth; 

I've seen people lay our wet or dry paper on top of a surface plate for lapping small parts. Sounds like a good opportunity to get grit all over the plate to me.


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## Highpower

DaveH said:


> What about 1/2"- 5/8"  thick float plate glass - suposed to be vey flat. I have no idea if it is, or if it would be suitable for your application.
> 
> Just a thought
> 
> DaveH


Let's see now...... plate glass  -- heavy cast iron part -- my butter fingers.......  Ummmmmmm........  



Tony Wells said:


> Well Dave, since we're mentioning substitutes, I would be remiss if I didn't mention that one of my early employers started his shop with a _tombstone_ for a surface plate. They can be polished granite, you know.
> 
> I've often wondered if the guys who come cert and lap would accommodate that, or would they tell you to get lost.


Oh PLEASE guys? I'm just dying to get this thing lapped!  



DaveH said:


> Tony,
> 
> I shudder to think what is going thro Willie's head now
> 
> DaveH


Other than that breeze through my ears?



mnmh said:


> If you're talking about scraping small parts then I would buy a small black surface plate from Enco and use their free shipping code because the surface plate would be light enough to ship UPS.
> 
> Ed


I'm thinking more like 18 x 24 Ed. Some consider that a "small" plate. Go figure. Still truck shipment territory I'm afraid.  



Jerry Ekstrom said:


> I have no idea but what about machinery grout, just make a mold the size you want and pour it in it drys water level extremely hard and would lap like stone, and the cost is not to bad. Just a though.
> 
> Jerry.


 There would be a problem with dimensional changes do to temperature and humidity fluctuations I'm afraid. Granite is very stable in that regard which is why they use it.



Tony Wells said:


> I've seen people lay our wet or dry paper on top of a surface plate for lapping small parts. Sounds like a good opportunity to get grit all over the plate to me.


At least they didn't use Clover compound, eh?


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## Tony Wells

Highpower said:


> At least they didn't use Clover compound, eh?



Well, I can't say I've never seen it done, and I have jumped out some people for abuse of surface plates. Some people don't know how expensive they can be.

I've always wanted a cast iron lap like the surface plate guys use. They seem to last forever. But then, I'd have to have all the other goodies to check the work, ya know? I do know it's a lot of work. One of our plates had a pretty good dip in in due the the Trimos air float dying, and people bring the part to it rather than floating the Trimos over to it. I had to help the guy lap it that time. It's hard work to get a 0.0032 hole worked out a pink. I moved that Trimos over to a black plate after that, then fixed the air system.


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## Highpower

Thanks Dave! It's nice to know I can always count on you to come up with a solution when things get tough. 
Alas..... I seem to have stumbled upon "Plan B".

Just as I was ready to throw in the towel and violate the pink, I made a last ditch effort and called a KBC Tools store across the river from me and inquired about what they had to offer in black granite. Struck out naturally - nothing in stock. Then I clenched my teeth and asked about shipping charges, awaiting the dreaded answer. The gentleman on the phone paused for a moment and said "Welllllll..... if you don't mind _waiting_ a few weeks, I can put one on my regular stock order and it will be delivered here to the store. You can drive over and pick it up and you won't have to pay shipping.




Now all I have to do is figure out how to sneak it past SWMBO.


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## Tony Wells

If the job is not critical down into the tenths, consider getting a piece cut from a blanchard ground tooling plate. Most steel houses can furnish that, and cheaper than granite, I would think. It has been when I've bought it, and you won't ruin it so easily.


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## Highpower

Tony Wells said:


> Most steel houses can furnish that,


Tony, you'll have to define "steel house" for me. The only places I'm used to dealing with are Speedy Metals, Metal Express, Metal Supermarkets, and similar on-line. Just the typical "general" suppliers. I don't know of anyone (around here at least) that stocks ground tooling plate. 

The import 18 x 24 granite plate (Chinese tombstone?) from KBC is $127. Blanchard ground "tooling" plate even *sounds* more expensive.
But you can color me clueless in this area.


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## Tony Wells

Well, the first one that comes to mind is EMJ (Jorgesen Steel). They are a larger company that services various industries in metal good manufacture. It may be a regional thing, and I don't remember where you are, so I can't give you a local example. However, Onlinemetals claims to carry it. Just Google tooling plate, or blanchard ground plate. It's pretty common.I don't know for sure about price comparison, since I never have thought about using tooling plate for a surface plate or a lapping plate, but it should be worth checking out.


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## Highpower

Ok, Google is NOT my friend!  

Blanchard ground plate.

Tony,
Another side bar question. Are brayer's thoroughly cleaned after every use, or do you just leave them "inked" up? That's one detail I've never seen discussed before. 

p.s.
I'm in the Gateway to the West. Or emergency exit to the East, depending on how you want to look at it.


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## Tony Wells

Highpower said:


> Ok, Google is NOT my friend!
> 
> Blanchard ground plate.
> 
> Tony,
> Another side bar question. Are brayer's thoroughly cleaned after every use, or do you just leave them "inked" up? That's one detail I've never seen discussed before.
> 
> p.s.
> I'm in the Gateway to the West. Or emergency exit to the East, depending on how you want to look at it.




Brayers should be kept clean. That said, during a session, it's not imperative that they be completely free of all ink or dye, but afterwards, they should be cleaned thoroughly. Old dye or ink can interfere with smooth application, so you want to start a job with a fresh, smooth brayer surface.


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## Highpower

Thanks Tony. Pretty much what I expected. I had a look at the tech sheet on my Dykem Hi-Spot Paste and found this:



> • Removable with Dykem® Remover &
> Cleaner.


Any idea if this will damage a soft rubber brayer? Or do you have a better recommendation for a cleaner to use?
I had sent the same question to dymon.com but their email bounced.  
	

		
			
		

		
	

View attachment 689


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## Tony Wells

I'd be very cautious with Dykem remover. A thorough wipedown with paper towels first, then a damp, and only damp with the remover would probably be fine. Thing is, you don't want  to saturate the brayer with any solvent. If you only use damp wipes, it won't soak in. The surface will dry quickly enough.


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