# Are gibs supposed to have a "rough" surface?



## lSherlockl (May 3, 2021)

Hello,

Was doing some prep work for the big move of pm-932v to the basement (de-palleting) and also had to pull the table. 

Being a new to this kind of machinery I had a question about the gib, pictured is my x axis gib. And that is the face that mates to the male side of the dovetail on the table. The side facing the other way so to the front side of the saddle is just smooth with two marks from the x axis locks. And the narrow top and bottom faces are lightly ribbed

Now I know scraping is a thing and I understand that concept this just seemed quite rough/aggresive which just had me curious If this is right/expected or if gibs are normally scrapped. I feel like it must be scraped or some attempt at something akin to scraping given the haphazard orientations but just didn't quite look as much like what I had seen when reading about scraping.

I can try and get a better image showing more detail as it seems pretty pronounced.

I haven't checked it for flatness yet waiting for my stone to hopefully show up, but I guess my bandsaw table should give me a rough idea.


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## Braeden P (May 3, 2021)

that scraping looks ok it doesn't have to be pretty and a band saw table will be nowhere near close to a surface plate and will not give you accurate reading and you will get a different reading everytime.


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## markba633csi (May 3, 2021)

That's OK, a perfectly mirror smooth surface is not desired or needed
-Mark


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## silence dogood (May 3, 2021)

Those gibs look perfect.  You want tiny spaces like so that there are places to hold the film of oil.


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## lSherlockl (May 3, 2021)

thanks for the info!

it just seemed much deeper or aggressive than expected. From what I had read or seen pictures of scraping anyhow, there is a little bit of scraping on the Y axis ways that i can see and that is much much much shallower/finer. 

I don't think there is a great way to measure the depth of the scraping as well the gib is angled, but ill just sanity check the surface is nominally flat against the surface stone once it gets here, and just leave it alone.


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## francist (May 3, 2021)

No expert here but something about those marks look more like grinder tracks than hand scraping. Here’s a close-up. Am I imagining things?

-frank


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## graham-xrf (May 3, 2021)

It has no characteristic consistent with hand scraping, nor even Biax-type machine scraping. To be honest, my first impression was etched exposed crystalline pattern as one might see on zinc, but I think I agree that the surface was probably roughed up with a grinder. I guess that approach would work, and @markba633csi is right in that you do not want a fine finish flat surface there.

The traditionalists do like moon-crescent flaking for a nice appearance oil retention surface, but such is not actually necessary. Nobody can see in there.


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## lSherlockl (May 3, 2021)

francist said:


> No expert here but something about those marks look more like grinder tracks than hand scraping. Here’s a close-up. Am I imagining things?
> 
> -frank
> View attachment 364714


yeah that was really why the question was raised in the first place ill try and get a better close up snap.

i feel my right angle grinder or Dremel skills would be above the fairly wild variation that at least "appears" to be by eye or running a finger over it.

But so long as its flat as other said it should be fine, I may run a stone over it if any of it seems too rough


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## Janderso (May 3, 2021)

Maybe the manufacturer is trying to attain the distinction of having hand scraped gibs?
They are interesting.


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## davidpbest (May 3, 2021)

That looks like a pretty crude attempt to fit a gib to the dovetails.  If that were mine, I would stone it lightly to remove any burrs, then check flatness and percentage contact against a surface plate with Prussian Blue.


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## Dabbler (May 3, 2021)

+1 to @davidpbest comments - The mainconsideration is that the surface is flat.  it would be nice, to have 20 or so points of contact per inch, but frankly wear in will provide some of that.  

Stoning it and checking against a surface plat is a good idea.  It will insure against significant premature wear


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## markba633csi (May 3, 2021)

That does look a little rougher than I thought after looking closer- definitely check it for flatness and maybe lap it a bit more
-Mark


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## Braeden P (May 3, 2021)

Using a die grinder is a way to scrape hardened ways just very light touch.


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## silence dogood (May 3, 2021)

With the blown up picture, yes now I can see scratches.  But how deep are they?  I'll bet that they are less than a thousand, and it's nothing to worry about.   If you feel a burr with your finger then run a stone a couple of times.   I agree with Dabbler and Dave Best,  make sure that they are flat.  Make sure that after you mount the gibs, that the gib screws are properly adjusted.  They will wear.  But with the gib screws carefully adjusted they should wear evenly.


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## 9t8z28 (May 3, 2021)

My 932 gibs look identical to yours.  IMO, they are definitely scraped, as to how and with what and to what extent, we will never know.  They definitely could be better but that would be up to your to fix.  I actually had a bent gib when I got mine.  When I would lock the Y-axis the X-axis handwheel became very hard to turn.  I know it sounds unlikely that this would cause the entire saddle to flex but that was the case.  PM sent me a replacement that was obviously just a tapered section of gib that needs to be fitted.  
If I were you I would make sure there are no sharp edges, clean them up to your liking, install them and adjust the gibs to your satisfaction.   Put and indicator on each axis and pull on the table and see what you get with the gibs locked and unlocked.  Again, adjust to your preference.   If you find the table moves more to one side I would correct the gib and then rescrape it flate.  
Somewhat off topic but whats a 932V?  I have a 932M, not sure what the V stands for.


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## lSherlockl (May 4, 2021)

Here are two other shots a bit closer/ enhanced to show flavor or I mean detail.

Surprisingly not much in the way of sharp edges few spots along the edges could use a touch up.

Though I will say I think some of the deep spots may be a bit more than a thou, using the finest measuring device of a finger. As I am not sure it's worth the fight to figure out how to set it up given it's shape to check it with a test indicator.

That and still waiting for surface plate. But I did want to at least provide better pics and the followup to it so if someone else new to this has the same question they will have completed info.

Oh and @9t8z28 the PM 932V is the variable speed variant of the PM 932 family. Belt driven 3phase VFD 1.5Hp motor only comes as the basic so no other power feeds otherwise "same" castings/machine.


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## macardoso (May 4, 2021)

I agree with above. Blue it up against something flat. IF the contact is moderately even across the surface then they should be good to go. Yes, hand scraped gibs would be nice, but I can't afford them!

IMO it looks like a fairly decent go at "scraping" with some sort of rotary abrasive tool. Maybe a flap wheel on a small angle grinder? If done right it should work fine.


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## 9t8z28 (May 6, 2021)

lSherlockl said:


> Here are two other shots a bit closer/ enhanced to show flavor or I mean detail.
> 
> Surprisingly not much in the way of sharp edges few spots along the edges could use a touch up.
> 
> ...


I didn't know such a machine could be purchased.  
The surface plate wont tell you all you need to know.  You still don't know if the ways are straight.  Thats why I said scrape the gib to the machine, not the other way around.  This is how Stefan Gotteswinter did his machine as well.


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