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Stoning Or Filing Your Milling Machine Table

JamesSX2_7

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#1
Hello,

I wish to tram in the head of my milling machine, so was reading up about it.
It is suggested that before doing any measurements, I "stone" my table to get rid of high spots.
These high spots are caused by dropping items onto the table. I've tried to be careful, but still managed to drop the odd item.

I bit for reading about "stoning" has indicated that there are machinists that stone, and those that file!

Some advocate using a hard stone (like India stone or harder) and some say use a dull file (file that has itself been stoned). The stone or dull file is slid along the table sideways and only cuts into the raised bits.

Has anyone here got any first hand information on this matter?
How do I know if my dulled file is dull enough?

Thanks,
James.
 

Uglydog

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#2
File or Stone.
I wouldn't take a file to my table unless there is a huge burr.
If you've been reasonably careful then a stone will be great.
Consider this: after brushing off any accumulated swarf wipe the table down with a shop towel.
Run your hand over the table. Usually you will be able to feel burrs.
Take a clean stone, note- clean not necessarily new, and move the stone across the table.
You should be able to feel the stone catch on any burrs.
Regardless, be careful that you don't cut valleys into the table as they will be as bad as a burr.
As a general rule I wouldn't attack my tables with a file, be careful not to overstone.

Daryl
MN
 

RJSakowski

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#3
I would stone with a fine grit stone but I would make sure that the surface of the stone is flat. If the stone is hollowed, the edge will be cutting and more likely to gouge the table. When you stone the burrs, you will see a polished surface on the burr that gradually gets larger as you stone. Stop when the polished surface is just astarting to blend in with the table surface.

If you think about it, stoning a flat surface takes a lot of work to remove .0001".

I wouldn't substitute something like sandpaper or crocus cloth for the flat stone.
 

higgite

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#4
FWIW, an article I read on the subject suggested wetting the table with something like WD40 before stoning, spreading evenly with your hand. The purpose as I recall was to more or less “float” the stone so it would only hit the high spots and not otherwise mar the table. I don’t know enough about it to know if that step is necessary, but I used it on mine with a 320 grit alox stone and it worked to smooth out the couple of bumps I had.

Tom
 

Kernbigo

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#5
The rule i always herd was stone first and if the stone would not remove the burr than file and go back to the stone again
 

chips&more

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#6
I don’t use a stone or a file. I have a large, flat and heavy chunk of metal that I run over the table and burnish the high spots…Dave
 

Ulma Doctor

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#7
sweep the table with a dial indicator on the column
i'd turn the file into a scraper and hit (lightly scrape) any raised spots felt by a bare hand ran across the surface.
then a flat, medium grit combination stone to the affected areas using dollar store windex as the cutting agent.
remove the windex residue immediatly after stoning with a paper towel or lint free cloth
do not scrub hard with the stone. hit the imperfections at 45* angles to the direction of travel
sweep your table again
repeat as necessary
 

JamesSX2_7

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#8
Hello,
Thanks for all your replies.

I decided to try and measure these dents first with a dial indicator.
As best as I can measure the dents were hollows only, no raised spot.
I decided this was OK and didn't stone my table.

I did though buy a stone, a Norton Sportsman Stone - fine on one side and course on the other.
I felt I should stone all the bits I bolt to the table.

I started with my angle plate. This was very revealing.
The slots had raised edges. I did break the corners with a file, but the raised section was about 3-5mm wide!
This was easily felt with the stone, but didn't need much to feel it evened out.

I also stoned the bottom of my vise - a home made contraption given to me when I first bought the mill.
This vise has cap head screws in the bottom to hold the fixed jaw and the fixed screw plate in place (don't know what else to call it).
One of these screws was protruding just enough to catch the stone.
A bit of rubbing didn't seem to cut it back, so I removed and ground the screw head down. No more issues.

It is quite possible the dents in the table come from tightening down on a non-flat item, or from manufacture.
I would recommend checking anything you bolt down, as you never know.

James.
 

Uglydog

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#9
It is quite possible the dents in the table come from tightening down on a non-flat item, or from manufacture.
I would recommend checking anything you bolt down, as you never know.
Already making great suggestions!!

Daryl
MN
 

JamesSX2_7

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#10
Hi,

Received a new vise today - more about the vise in another thread.
Thought I would write about the bottom of the vise here.

Vise is a Accu-lock clone with a swivel base.
So, it actually has two clamp down faces, depending on if you want the swivel or not.

Started by looking at the vise itself. Overall very happy with it, but two small items I corrected.
The outer edge was filed smooth(ish) rather than left as a sharp corners, but no such treatment of the inner sharp corners.
I didn't like these, so I filed them myself - see blue circle in following photo.
The other was a doozy: the protractor pointer hung BELOW the base - see red circle.
This would have scratched my table badly, and been bent over anyway. A little cutting and filing sorted this out.
20160812_152723.jpg


I then looked at the bottom of the swivel base.
This casting wasn't the same quality as the vise, but acceptable for what it does.
No sticking out pointers here :)
I did need to file the internal edges as before.

I then applied a little WD40 and took my stone to the bottoms.
The vise was OK thought there did seem to be a minor high spot.
The base had 2 high spots near the centre.
20160812_155408.jpg


These may have been caused by rough treatment, as I doubt the grinding had left them.
I did note the bottom of the vise and base were very scratched.

Anyway, I'm happy with the purchase, and happier that they didn't cause any damage to my mill table.
I really recommend an inspection and clean up BEFORE tightening these things down.
 

Attachments

Bob Korves

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#11
I use either a fine grit, FLAT Norton India stone with WD40 or a 500 grit FLAT ceramic stone with generic Windex on burs. Like was said before, slide it around gently until you feel it catch on something, and then work on that area fairly gently until the stone slides smoothly without feeling the bur any more. Wipe the table clean after stoning it, or you will continue to grind the grit into the table. Most of all, don't create scratches, burs, and dings in the first place by being careful about how and what you put on the table. Slide parts onto the table gently over the corner of the table, placing them down gently into position. Don't drop wrenches and stuff on the table, in fact, keep wrenches and other tools off the table. Also, no cutting tools, or anything else for that matter, on the table. Just the vise and the fixtures and the work, all handled carefully. There is also no bye if you have a well worn and damaged table. You can be working at making it better, or at making it worse. It is up to you. Cast iron precision surfaces are easy to damage.
 

talvare

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#12
Just wanted to add to what Bob said about being careful with the surface of your mill table. I also never lay tooling on the table. I made a small 1/4" plywood surface with two runners on the bottom side that fit into the T-slots and keep it on the table at one end just for setting tooling, etc. on. My mill table had plenty of imperfections from the previous owner when I bought it and I don't want to add to it !

Ted