What's new
What's new

scraping height gauge

scrap maker

Plastic
Joined
Dec 18, 2020
Location
Bucktown PA
could anyone help me with scraping in a height gauge, does any one know where it should hinge because there is two flats and how much percent contact should I have sorry I am new to this
 
Any pictures?

I've never done one, but I would think you would want the outside edges a touch higher than the middle so it doesn't rock or let debris under the edge (think like a cup). Contact area kinda depends on how accurate it is/should-be and how much you intend to use it.
 
well i could make it cup shaped but i think that just making it flat would work making it cup shape defeats what i am trying to i want to make it flat for practice.
 
Log in | The Hobby-Machinist click on t and it should show a picture sorry I don’t know how else to attach the picture.

It is an interesting shape :). Technically the hinge should be about 30% in from each end. The issue is that you have two rails touching as opposed to a continuous surface, which might change the hinge point. Considering all of that you still want to make sure that the hinge is neither on the corners nor in the center, and the thing does not rock. You should shoot for at least 50% coverage and at least 20 PPI.


dee
;-D
 
....i want to make it flat for practice.

Good to do such practice. Not helpful to do it on a SG or other measuring or reference device as first project.. or "attempt".

Better to learn how to create a specific outcome on a plain CI plate.

Once comfortable that you can generate the desired result, THEN apply what you have learned to a level, SE, SG. Or machine-tool.

2CW
 
This is my first time scraping and I just watched videos and read about it and that is all I know I plan on going to a Richard king class too.
 
This is my first time scraping and I just watched videos and read about it and that is all I know I plan on going to a Richard king class too.

If you take the class, do your initial attempts on plain metal, save the base to take to the class with you. There you'll have hands-on guidance as to how to best go about it as well as appropriate checking and correction as it proceeds.
 
I certainly enjoy scraping, but the OP’s project imho is one for hardened ground toolsteel. Not cast iron.

L7
 
I certainly enjoy scraping, but the OP’s project imho is one for hardened ground toolsteel. Not cast iron.

L7

Height guage base?

I'd have to disagree.

Same as all the levels and SE's, ALL my (many!) OLD-but-good verniers, B&S and Scherr almost exclusively, and clear to 40+ inches - are Cast Iron base.

So, too, the Starret-Webber Digi-Check, Cattlejack-Gage Pla-Check, B&S Height-i-cator castings. Never took much notice of their "buttons" or equivalent, to be fair. Just figured the makers knew their s**t better'n I did.

:D

Broader base, CI works well, lasts a long time, positions readily, is more easily put-right than hardened and ground tool-steel. The inclusions in CI can make it plenty "hard" as far as resisting wear.
 
I'm my experience 50+ years of scraping things, Starrett height gages like the one shown is hardened Cast iron as you see in my lathe beds. Some of the cheap ones are soft, but I would say 1 in 500 are soft. In all I have seen that are worn are high in the middle because dirt drags under the edges. The best way of checking this is to set a .0001" indicator out away from the edge doubling the length and set it on zero. then carefully press on the opposite edges with your thumbs and see movement. Then scrape accordingly . One can step scrape it by scraping the middle 25% then scrape the middle 50% and finishing the middle out 75% until it doesn't rock. Remember the error will be double of the reading as you multiplied the error. Lowering the middle 40% by a few tenths is desirable if your using it strictly on a surface plate, especially if one doesn't wipe the surface with your hand and little bits of crud laps off the edges and it begins to wear high in the middle. I would say more, but won't
 
I presume Rich was talking about common use of a surface plate and accessories. That is, do you pay attention to clean the plate before setting stuff on it? And the hand is very sensitive in detecting small particles. I was taught on gauge block use that wiping on the heel of the hand by the thumb was the best practice for checking before wringing blocks together. I always presumed (yeah, I know) that toolmakers' long experience was that the area there tended to be the cleanest since you'd normally use the opposite edge of the palm when sweeping the surface plate. Realistically, guys are not going to be trotting down to the hand wash station every time they're making a change with gauge blocks.
 
It looks good and should be a true 90* to the column (verticle) looking straight and from the side.

For ones with a full foot, three points was good having two spots at the front and one at the back.
Just scrape the middle area witness so it is perhaps .0002 low, this so the wear pattern will show up when it needs to be re scraped.

Should be able to hang an indicator on and slide up and down to check square pretty close.
 
Last edited:
I did some more and there is more contact on the edges than the middle and I was using hss blade for it but tomorrow I am getting a 1 inch carbide Anderson scraper so I will have to try that out it is an old starrett in a wooden tool box and all of the tools in it was from 1900s to 1930s so it is old I did some practice on a broken center finder and that is soft so it was easy to do.
 
I did some more and there is more contact on the edges than the middle and I was using hss blade for it but tomorrow I am getting a 1 inch carbide Anderson scraper so I will have to try that out

Sounds as it you are on the right trail. "Understanding" the goal is the most important part.

There's no real weight on 'em relative to the bearing capability of the foot. Hence not that rapid a rate of wear if it is positioned with care and respect for itself and the surface while being used.

Your "working" surface around the edges can be fairly narrow relative to the relieved area towards the "geometric center" and still not need restoral very often.

As-in it might not have been done before to this one since it left the factory. And may not need it again, going forward, once you put it right.

Not as it it was a workboot sole or a snow tire on the pickup!

:D
 








 
Back
Top