Tips for scraping around oil grooves

[AndySomogyi]

I’m doing some rough scraping, and need to move a lot of material with a hand scraper.

I’m finding it really annoying working around the oil grooves, scraper always catches and you can’t make a long stroke.

Is it a bad idea to rough scrape parallel to the grooves? so to get a longer stroke. I found this kinds works, I’m just not sure if it would result in issues.

Ive got about 0.015 thickness to scrape down before it’s flat. This is the first print and after a 5 passes or so, I can fit a 0.015 feeler gauge under a straight edge .

 

[Rex Walters]

I think edges around holes or oil grooves are always a pain, sadly.

Not sure if it passes muster, but what worked for me to get around tricky areas like these was to first scrape the entire surface with long strokes that completely avoid the edges then shorten up my stroke and focus just on the edges themselves. It made for occasionally weird blue-ups (often showing more focus - and passes - needed around the edges) but it worked.

I also think the most important thing is to keep more than half of the blade on the surface at the end of the stroke, and at about 45° to the edge. The shorter strokes won't all be in line with the long strokes, but I reasoned that catching an edge was worse than an uglier pattern (all that matters is PPI in the end, not how you get there).

 

[Weldingrod1]

Wow! 0.015" is a LOT to scrape! You might want to give it a few kisses with a flap wheel disc or go ahead and machine it...

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[AndySomogyi]

Wow! 0.015" is a LOT to scrape! You might want to give it a few kisses with a flap wheel disc or go ahead and machine it...

Sent from my SM-G892A using Tapatalk

I wish I could machine it, but this is my only mill. I did hit the high spots with an angle grinder, that took most of them down to about 0.007 now.

This wasn’t even the worst, I ended up taking about 0.025 off the saddle, to get rid of the wallows.

Grizzly quality at its finest


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[Rex Walters]

Oh! I read that as 0.0015"! My brain wouldn't even let me see it correctly.

Yeah, big bastard file (in every sense) or angle grinder to start. <laugh>

 

[AndySomogyi]

Oh! I read that as 0.0015"! My brain wouldn't even let me see it correctly.

Yeah, big bastard file (in every sense) or angle grinder to start.

Yes, massive face palm , I should have used a big ass file to get the highs down.

I tried an angle grinder, just didn’t work too well, in that if you’re careful, it doesn’t take much more off than a scraper, and it’s hard to control and super easy to screw something up.

But yeah, 15 thousands, and this wasn’t even the worst part of this mill.

I’m still astonished at how the factory could have made a surface THIS bad. Weird thing is the ground ways that this mates to are actually pretty good, it’s just anything that involves any manual work is a disaster, they all look like they’ve been cut with an axe.


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[AndySomogyi]

Oh! I read that as 0.0015"! My brain wouldn't even let me see it correctly.

Yeah, big bastard file (in every sense) or angle grinder to start. <laugh>

Thanks @Rex Walters , Good idea about the file, ha ha, it’s sooo simple. Worked great, took off that 10-15 thou in a few minutes. I used the other way as a guide to keep them kinda co-planar.

Got a decent surface now to start scraping it in.

 

[Rex Walters]

I've been using files a lot more often in my work lately. Albeit not in preparation for scraping!

I almost always draw file to remove milling marks prior to lapping on emory these days. Saves time making the parts look nice.