Surface Grinding

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Wolfgang
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Re: Surface Grinding

Post by Wolfgang »

earlgo wrote: Tue Jun 14, 2022 1:09 pm I got a little carried away with this birthday present for a friend. Elm box and jeweled 1.5 inch hobby vise. Gift vise.jpg My friend liked it though.
--earlgo
Beautiful!

My high school machine shop teacher taught us to do it with a wooden dowel and valve lapping compound, in a drill press. We'd clamp a parallel onto the table to slide the work along in order to keep the swirls in a straight line. The spacing of said swirls was up to the artist, ahem, more or less gifted students.
In a vertical mill this would be a cinch.
One of our projects was a cantilever clamp, aka Kant Twist, and I finished the outside of same with said swirls.
Thing is, those swirls hold oil quite well, thus improving corrosion resistance to some extend.
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ctwo
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Re: Surface Grinding

Post by ctwo »

I also heard oil can wick around the metal. I bought a hotshot sprayer and keep it with AFT cut with kero and give my machines a sprits, hoping the mist distributes over time. Doesn't seem to work all that great.
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choprboy
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Re: Surface Grinding

Post by choprboy »

So after lusting for a long while, I finally purchased a surface grinder project machine (though I don't quite have a place to put it yet...). A DoAll VS618. Been sitting for 10 years, previously used in a plastic injection shop. Something I didn't expect, the ways have plastic (Ryton?) strips epoxied on. This was apparently a thing with the DoAll DH-series, didn't know/haven't confirmed it on the VS-series.

Seems the strips have worn quite a bit, there is a lot of stutter from the X axis gear driving the rack do to too little clearance I think... Anyone know where to purchase replacement strips? Best I have been able to find is Teflon sheets that would have to be cut down and punched/scrapped to fit the ways.
Last edited by choprboy on Wed Jun 15, 2022 1:40 pm, edited 1 time in total.
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GlennW
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Re: Surface Grinding

Post by GlennW »

Perhaps Turcite?
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Operating machines is perfectly safe......until you forget how dangerous it really is!
choprboy
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Re: Surface Grinding

Post by choprboy »

Perhaps, it is redish-brown in color, epoxied to the ways. Various forums say Ryton, Turcite, Teflon... The existing have cracked/chipped in a few places, have fine (what seem like evenly spaced) horizontal grooves the length of the way. It's not exactly clear to me if that was intentional or the result of grit and wear (I suspect the latter but not sure).

McMaster has Acetal strips as well, which are fairly cheap compared to Teflon. I suppose the other option would be to completely remove the plastic and grind/scrape the ways in, figure out some way to deal with the drive gear/rack offset.
jcfx
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Re: Surface Grinding

Post by jcfx »

What earlgo did to his vise is also called 'engine turning' don't know how that term came to be.
It can also be dome with Cratex rubberized abrasives, attached is a PDF of Cratex's How To manual ....
Engine turning.pdf
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ctwo
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Re: Surface Grinding

Post by ctwo »

I worked in this square so it's, square :D I notice all of my shop V blocks are not square but slightly obtuse. Is there a reason for that?

Image Image
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
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GlennW
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Re: Surface Grinding

Post by GlennW »

How did you determine that your square was square?
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Harold_V
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Re: Surface Grinding

Post by Harold_V »

Hmmm. Seems rather odd to me that Johnny is the only guy marching in time.
I'm with Glenn. How did you determine the square is square? Odds dictate that it's the problem.

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ctwo
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Re: Surface Grinding

Post by ctwo »

I used the DTI as shown on the small surface plate. I set the DTI using my shop made cylinder square, which varies about 3 tenths around the circumference, and I verified with commercial squares.

The V blocks are not out by tenths, the angle is probably over 50 degrees so it's intentional, and it's not 60 degrees. One set is a B&S shop grade and I can see the mill marks. Another set I think is Starrett and I believe the angles of the two sets are the same, but I'll need to check. My V blocks that have square Vs are ground.
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
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ctwo
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Re: Surface Grinding

Post by ctwo »

For reference, this is not a good setup. It makes things blow up.

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Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
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ctwo
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Re: Surface Grinding

Post by ctwo »

Here is the B&S pair are the same, and the Starretts actually are square. So I have three blocks with unsquare Vs.

Image Image
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
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