PDA

View Full Version : Frosting or Scraped?



pntrbl
10-29-2007, 04:12 AM
I've got the base on my XLO torn down and I'm thinking for once in my life I got a machine that isn't all wore out. Here's a pic of one of the ways for the Y axis.

http://i115.photobucket.com/albums/n300/pntrbl/Frost.jpg

I don't know enough to know handscraping from frosting, but if you look deep in the corner there's evidence of circular cuts. Possibly a dovetail cutter? Then frosting to make it look pretty?

Could be it's just spent it's life well lubricated. It's got a Bjur One Shot on it and I'm definitely impressed with the thought put into the lube system. Here's a shot of the saddle that shows the grooves for keeping oil under the table.

http://i115.photobucket.com/albums/n300/pntrbl/Lube.jpg

The tapered gibs even have oil passages ......

SP

Doc Nickel
10-29-2007, 04:22 AM
I'm pretty sure that's frosting- just an antistiction oil-retention pattern.

But from what you're asking, it means the same thing; it's still a visible pattern, which strongly indicates wear is minimal. (Assuming, of course, someone hasn't reapplied it in an effort to make it look just that. To tell for sure, proper measurement is required.)

Doc.

pntrbl
10-29-2007, 04:34 AM
I just realized the back of the knee doesn't have the frosting so that must be what it is. All circular there where no one but a nut like me would ever see it.

http://i115.photobucket.com/albums/n300/pntrbl/Knee.jpg

But Jeez, it's all there! I think the Machine Gods are smiling on me for sticking with the rescue mission on my 11" Logan. It's payback.

SP

Forrest Addy
10-29-2007, 05:04 AM
"Frosting" and "flaking" mean pretty much the same thing and the usage depends on where you came into the trade. Either is accptable and fully descriptive. It's a partly decorative process alleged to hold oil and improve lubrication when applied to a scraped machine surface.

"Scraping" however is done to fit and align machine elements and to refine the bearing and accuracy of axis slides. It's not unusual to find vestiges of cutter marks in a scraped surface, particularly on surfaces never seen by the owner or user. If the surface has good over-all bearing there's no point in taking a more cuts just to make it pretty.

The back side of that knee does look like its been milled and never scraped. Here again if the surface bears and the alignments are right one might hesitate to scrape it for bearing. There may be no beneft in doing so. Never the less, I'd give the machine and its manufacturer a downcheck if I found such a condition. OTH I've seen machines last for 30 years on the production floor that when disassembled showed evidence of machine way against machined way - sans scraping.

If it wears well as-machined does it really need to be scraped? Well, discussion of the merits could go on for some time but I'd say yes right up front. Scraped and fitted way bearings are not only more durable but stiffer and smoother operating than machined surfaces regardless of accuracy - a point long established in several legal precidents.

If the manufacturer's brochure listed hand scraped and fitted way bearings as salient features, I'd expect no less when I dismantled it for a re-scrape a few years in the future. If I discovered concealed as-machined way bearings and the manufacturer was still in business I'd expect a hefty price adjustment whether the warranty period was up or not.

rbregn
10-29-2007, 07:32 AM
I have a one shot lube system on my mill also. You want to make it better? Plumb your one shot into a manifold that has a different port for each system that gets oil. The more the better. That way you can oil each system buy its self. I have seen were one area will plug up and then it won't get no oil, but if you separate each area, you can pump until you see oil and know it is lubed.

J Tiers
10-29-2007, 08:21 AM
Given the pattern of "frosting", which is better than the average ebay idiot, but not as good as a good factory job. I'd offer the opinion that the machine may have been re-fitted by someone who may have had some skills.

If it had been an ebay idiot, there is no way the knee back would have been touched.

The alinements may not have been all scraped-in, however, since it looks like the frosting is OVER the wear in the picture....

oldtiffie
10-29-2007, 08:32 AM
I just realized the back of the knee doesn't have the frosting so that must be what it is. All circular there where no one but a nut like me would ever see it.

http://i115.photobucket.com/albums/n300/pntrbl/Knee.jpg

But Jeez, it's all there! I think the Machine Gods are smiling on me for sticking with the rescue mission on my 11" Logan. It's payback.

SP

Thanks SP.

I don't think I'd worry as that "slide" is usually used in a "set and forget" mode as once set (and clamped) the "work/motion/travel" loads are taken on the "scraped" "X" and "Y" guides - which need to be - and are - "scraped" for the "lubrication" reasons given by others.

As it seems that you are not the original owner, I would doubt that the original supplier had any obligation toward you - at all - and particularly so if/as you don't have original purchase receipts and "Conditions of Sale" etc.

You have done very well indeed for yourself and are very fortunate to have such a good machine.

If I were you, I would not worry - at all - and perhaps spoil the experience - but I'd damn sure gloat about it - and with good reason - and enjoy it!!

pntrbl
10-29-2007, 12:23 PM
You got it Tiff. I'm gonna run it and see what happens! Probably a bunch of murdered end mills, but it came with some boxes of lambs for the slaughter.

http://i115.photobucket.com/albums/n300/pntrbl/EndMills.jpg

I've also got this dangerous looking thing.

http://i115.photobucket.com/albums/n300/pntrbl/Cutter.jpg

It's 6" in dia and with all those teeth would this be considered a roughing tool? Or is it possible all 8 teeth are close enough in depth for at least a dimensionally accurate finish cut?

SP

Fasttrack
10-29-2007, 02:24 PM
So uh ... what exactly is frosting?

So far i've got that it is added after scraping for better oil retention and lubrication but what is it?

I noticed that pattern on the j-head at school and was wondering what caused it.

Forrest Addy
10-29-2007, 02:44 PM
Fasttrack; Here's something I wrote back when on frosting:

Frosting

Here's one of the best kept secrets of the machine tool rebuilding racket: that pretty frosting pattern so much admired on exposed hand scraped ways is strictly for appearance and it works against the owner, shortening the life of the machine.

I've heard old hands sincerely speak in glowing terms of a "proper frosting job" as though it was both the crowning glory of a machine's appearance and a conscientiously applied means of retraining oil and reducing friction. Given a free hand a master scraper would apply an artistic scraping pattern to all exposed bare metal surfaces much as a prideful bosun's mate applies fancy rope-work to all quarterdeck fittings and appurtenances.

The master surface plates at Hunter's Point Shop 31 scraping bench had a handsome logo scraped in the center of their reference faces and the logos and all had near perfect bearing.

I've seen case hardened machine tool purchasers of vast experience be so taken with a beautifully frosted way surface they completely ignore the hazard it represents to machine tool longevity. They admire its glistening iridescent surface, run their hands over its hypnotic indentations and breathe "It takes a master scraping hand to do this."

I think BS, I used to do that by the acre with a Biax half moon power scraper and the brilliance of the scraping came from lapping the scraping edge with 9 micron diamond compound to a mirror finish. You can cover up a multitude of machine discrepancies with pretty frosting. It's eyecatching and beautiful. It's also the used machine tool sales equivalent of putting a banana in the rear axle of a used car to silence failing gears.

Most machine tools feature way wipers either of felt or sophisticated molded rubber designed to exclude grit and chips plus retain oil at the ends of the ways. Frosting done with a heavy hand may go as deep as 0.002 below the scraped surface and if done for maximum effect the frosted depressions are abrupt intersections ideally configured to trap dirt.

I'm a firm believer of frosting as much as 5% of the area in any fully housed way bearings as a means of lubricant retention and reducing "stiction" but never in ways intended to be exposed to chipflow or airborne dust. There, the ways should remain scraped smooth so the way wipers can better conform to the surface, excluding dirt and retaining oil. When the hand scraping pattern fades from the exposed ways in a few years, it's time for a re-scrape.

The secret to frosting is practice and preparation. Those pretty half moons are a product of hard core consistency. I've Biax half mooned about an acre (subjectively speaking) of way surface but still I'm no expert.

If I was learning frosting all over again, I'd first get several days of practice in one hour sessions to teach my muscles what to do. The actual learning takes place in the small hours of the morning. This part of skill building can't be rushed. Find any piece of flat scrap cast iron and practice running lines of flaking striving for consistent motion with the tool, perfect starts, and perfect stops. Hitting the work every time with the scraper running and in motion while making the first half moon the same in size and shape as the middle and the last will come but not for several days.

On a ground surface you get only one chance to make perfect display flaking. It's a Zen-like occupartion where abstract concentration and focus leads to the perfect manipulation of the tool.

If you've going after raw beauty in a display piece you need to diamond lap (9to 12 micron (green) lapping compound) the scrapers to mirror finishes and dead keen edges. Only then will they glint and sparkle for as long as you can keep the rust and tarnish off.

A handsome piece of decorative flaking requires some layout and some carpentered jigging. Decide the orientation and spacing of the flaking on the work.

Decide if you want to lay down parallel rows of flaking in one direction and then shift orientation and flake to other, or some combination in alternation. I've found a "twill" pattern is effective. Run some practice patterns before you make your decision.

Decide the scale of the flaking. Too small and the flaking looks busy, too large and it loses esthetic appeal. Ideally the flaking should commence and end right at the edges. Believe it or not, once you get the rhythm it's not difficult to start and stop right on the edges of the work without dinging them up. Just don't try to do to on purpose. Let muscle memory and Kentucky windage (and Zen) guide your hands.

Decide the spacing. Parallel rows should have about 1 1/2 times the pitch as the width of the flaking in my opinion. Here again you'll have to experiment.

Make a hardwood straight edge to guide the tool. Clamp it in place and practice using it. Use the straightedge for every row of flaking. This ensures linear perfection letting you ignore one variable so you can concentrate on those remaining.

If you have trouble with the starts and stops, clamp cast iron blocks flush with the edges for the scraper to start and stop on. This protects the crisp edges from taking a beating should you happen to blow the start.

Keep the chips vacuumed up. Running over chips leads to chipped scraper edges and scores in the scraped depressions.

Clean the surface thoroughly and lightly Arkansas stone the surface going in the direction of the ground finish. Use WD 40 for a cleaning and stoning lubricant. This stuff is in a class by itself when used for stoning.

As with any risk laden skill, knowledgeable cheaters always prosper.

The powered flaker is a marvelous tool. Customers love a pretty flaking job and the Biax HM-10 certainly shortens the time to do it.

Given my choice, I never frost or flake finish cuts of a routine scraping job. I can get the surface interruption for fully closed way bearings using a hand scraper or the Biax 7-ELM by selecting the right radius of the scraper edge and the way I manipulate it.

Whenever I got instructions for a nice "half moon flaking job" I'd bum the Biax HM-10 flaking tool and scrapers from my ex-employer and give the customer what he wanted. That’s at a surcharge and I’d give a written caution that half moon flaking is detrimental to the performance and life of way bearing wipers.

I made it a point to do a beautiful job of flaking for the customer knowing that the service life of way bearings exposed to the chip/coolant wash would be cut by a third or a half given usual shop negligence in servicing way bearing wipers. A thing of initial beauty is sometimes a compensation for reduced production life.

Continued next post

Forrest Addy
10-29-2007, 02:59 PM
From preceding post:

Bump frosting uses a regular hand scraper and its easy to do. Grab the scraper and lay the handle against your collar bone. Grip the scraper in your left hand at about a 70 degree angle to the work biasing it to the left edge. Make a fist with your right hand. Start it moving thumb up in a 7" circle in a vertical plane with the top of the arc going away from you. Move your rotating fist to intersect the scraper shank striking it 2 to 3" above the work. Bump bump bump in a steady rhythm asjusting techniqque until you get the desired effect. Be sure to have an upward component in the blow as you strike the scraper. The rotary motion of your fist is intended to provide this. The dynamics of you fist in motion, the direction of the blow, the scraper radius and the angle you hold it, etc are all ingredients that when present in the right balance give you perfet little chains of half moons.

Push frosting is easy to describe but it requires a great deal of practice if a good appearance is desired. You select a sharp scraper with only a little crown, apply the edge firmly to the work, and give the heel of the scraper handle a sharp bump with the heel of the hand or a rubber mallet. Ideally the frosted depressions should be oriented alternately 90 degrees and be near perfect squares.

Advocates of hand frosting frequently make a "mushroom" consisting of a knurled aluminum handle of normal proportions having a 1 3/4 dia mushroom knob on the heel. There is a #1 Morse internal taper in the business end designed to take the welded on shanks of a selection of frosting scrapers having end radii suited for each of a variety of frosting patterns including half moon.

Masters of the skill can produce a perfect checker board in alternating bearing points where the frosting is of uniform size and its orientation is in alternating direction. If done correctly any percentage of original bearing can be attained.

For half moon frosting, imagine the mushroom end of the scraper handle as a clock dial. The tool is used by gently striking the clock dial with a soft rubber maul or the heel of the hand. A right hander firmly grasps the scraper by the shank of the blade (not the handle) with the left hand. He applies it to the work with the left edge held firmly down. He striks the mushroom at about 4 o'clock with a repeated slightly down handed blows with the right. A series of half moons progress with each blow. The blows have to be absolutely consistant in force and direction.

You have to experiment. Individual anatomy has a pronounced effect. I have a mushroom handle and some odds and ends of frosting scrapers. While I've acquired the knack many time it has to be maintained through frequent practice.

If pretty scraping is all you desire, run about 5 passes of methodical hand scraping from three directions across any hunk of cast iron. Make sure each pass covers about 30% of the available surface, you use a mirror lapped carbide scraper with a 2 1/2" end radius, and the final pass catches the remainder of the original surface.

I don't teach any of my people to scrape for appearance. Only for bearing, fit, and texture. Fancy strokes that leave a pleasing appearance are fine so long as the basic requirements are satisfied. Some people have a knack for the subtle muscular control to produce J strokes, curved strokes, whatever. Others have difficulty acquiring it. I don't get into that because the presence or absence of distinctive scraping for appearance has no significant effect in the efficacy of the end result. It's advanced technique and I don't encourage developing it until the student achieves competence in the basics. You have to walk before you can run. Basketball coaches have a terrible time getting neophyte players to concentrate in the basic skills of the game. Problem is the boy prefer to perfect the showboat moves of their heroes and ignore the tedious stuff that wins the games. We wish the emulate excellence often at the expence of learning important fundamentals. This happens in scraping and every ether human activity.

dp
10-29-2007, 03:15 PM
Some interesting scraping links:

http://gfish.livejournal.com/187606.html
http://en.wikipedia.org/wiki/Hand_scraper
http://www.moglice.com/newsite/pages/straighttalk.html
http://home.comcast.net/~jaswensen/machines/straight_edge/straight_edge.html

SteveF
10-29-2007, 05:12 PM
And for the artwork version of scraping:

http://www.lindsayengraving.com/tour/index.html

Steve.

Fasttrack
10-29-2007, 05:49 PM
:eek:

Wow! That seems like alot of work!!! Thanks for sharing, i probably never would have known about it otherwise.

lazlo
10-29-2007, 07:12 PM
Given the pattern of "frosting", which is better than the average ebay idiot, but not as good as a good factory job.

That looks to me like hand-flaking from the factory. When the "Ebay idiots" add frosting with a Biax Half-moon Flaker, you can see that there are multi-levels of flaking, with the older, original flaking worn, and the new flaking on top that's bright and shiny.

I think the reason you're thinking it's not a good as a factory job is because Bridgeport now CNC flakes all their machines, so the Half-Moons are perfectly regular:

http://tinyurl.com/yslf26

"One of Dapra's customers, a major machine tool manufacturer in the Northeast, developed an innovative high-production power scraping application utilizing their Biax Power Scraper. Combining their Biax tool with a retired X, Y and Z axis CNC machine, this manufacturer was able to write a program to perform production half-moon scraping and flaking, while still having the scraper available for conventional short-run jobs."

http://www.dapra.com/biax/scrapers/images/custom2.jpg

pntrbl
10-29-2007, 07:52 PM
Well, thanx to all the conversation and education you guys have so kindly provided, I have had some real close and personal inspection with the ways on this machine, and I can now identify where it's worn. Whatever made the circular marks is the 1st thing to wear off and I can find areas at the ends etc. where those marks are still very much in evidence. Some areas have only what must have been a deeper scratch/cut/grind from the circular process because I can see single arcs that are far apart. The most worn areas have no circular marks at all. Just flaking ....

But hell, it's good enough for a mutt like me to learn on! :D

The cross and compound slides on my old Logan are so worn they come under the "bloody nuisance" category, but I'm using them like they are for now. Ya gotta start somewhere.

SP

oldtiffie
10-29-2007, 08:34 PM
Well, thanx to all the conversation and education you guys have so kindly provided, I have had some real close and personal inspection with the ways on this machine, and I can now identify where it's worn. Whatever made the circular marks is the 1st thing to wear off and I can find areas at the ends etc. where those marks are still very much in evidence. Some areas have only what must have been a deeper scratch/cut/grind from the circular process because I can see single arcs that are far apart. The most worn areas have no circular marks at all. Just flaking ....

But hell, it's good enough for a mutt like me to learn on! :D

The cross and compound slides on my old Logan are so worn they come under the "bloody nuisance" category, but I'm using them like they are for now. Ya gotta start somewhere.

SP

You've got the right attitude and the right mill too SP.

Just "cut to the chase", get on and use and enjoy your mill - which despite the "learn-ed comment" - I think is a real "goodie" which I'd be more than pleased to have in my shop.

You are very fortunate.

Just get on with it as your "advisers" are otherwise engaged in a largely unrelated "frolic" of their own. There is lot of noise and dust that has to settle yet.

They will come back to you and your mill - eventually - just let them slug it out - and stay clear.

And HTH would I know?

Because I get off on as many of these type of frolics as anyone else I suppose.

lazlo
10-29-2007, 08:53 PM
Just get on with it as your "advisers" are otherwise engaged in a largely unrelated "frolic" of their own.

What?! Are you saying that you think the responses to pntrbl's question about the flaking on his machine were unhelpful??

pntrbl certainly didn't think so Tiffie...

oldtiffie
10-29-2007, 09:24 PM
What?! Are you saying that you think the responses to pntrbl's question about the flaking on his machine were unhelpful??

pntrbl certainly didn't think so Tiffie...

No.

Once that was achieved it was developing into a fairly esoteric discussion.

The difference is that pntrbl thanked every one and "got on with it" as it seemed that he was satisfied that he had no cause for concern with what he could see in the posts.

He had no reason to be concerned about his mill for what he intended to use it for.

It seems to me that in fact his original post only showed what he had and how pleased he was with it and that he had no reasons for concern.

I think it was very generous of him to post the pics without complaint or undue "gloat".

He is one lucky guy.

lazlo
10-29-2007, 10:21 PM
He had no reason to be concerned about his mill for what he intended to use it for.

It seems to me that in fact his original post only showed what he had and how pleased he was with it and that he had no reasons for concern.

I think seems to you is the crucial part. It seemed to me, and apparently the other responders, that he was asking if the flaking was original, to determine how worn the ways were. And Doc and I registered opinions that the flaking was original, and that the machine has seen little wear.

So it seems odd for you to reply, immediately after pntrbl thanked everyone else for their advice, with a post entitled "Attitude" and apparently recommend that he ignore the advice given, and that he should "Just get on with it as your "advisers" are otherwise engaged in a largely unrelated "frolic" of their own"?

J Tiers
10-29-2007, 10:39 PM
Frolicking onwards....

I'm not so sure about the "factory job" for several reasons.

1) there are frosting marks in at least two different orientations, overlaid. (see oil groove picture)

2) The pattern isn't at ALL consistent, seems heavy on inside edge, and not well formed, with a few "runts" here and there. I'd not be proud of that job (although I myself like the square pattern a LOT better than the "swoops"), and I can't see a factory guy being proud of it either. Scraping guys seemed to be "artistes" and liked to do a good-looking job.

3) It LOOKS from the pictures that the frosting is OVER the modest wear marks. But I'd EXPECT the wear marks to intersect and "cover" the frosting in spots.

This doesn't mean that I think the machine is trash, but I think the frosting/flaking was done later, possibly in a rebuild.

lazlo
10-29-2007, 10:48 PM
there are frosting marks in at least two different orientations, overlaid. (see oil groove picture)

It's hard to tell if you can't see the machine in person, but that scraping looks consistent with the way I've seen other scrapers do hand flaking: they do rows of bump flaking in one direction across the entire way, and then overlap another set of bump flakes at 90 from the first set.


The pattern isn't at ALL consistent, seems heavy on inside edge, and not
...
It LOOKS from the pictures that the frosting is OVER the modest wear marks. But I'd EXPECT the wear marks to intersect and "cover" the frosting in spots.

I see what you're talking about JT, but I'm not sure either way -- I'm still leaning towards a slightly imperfect, hand-made factory flaking. I've seen when guys add a second layer of superficial flaking in person, and it's very obvious when you're standing there looking at it.

Another way that pntrbl can tell is to look at the oil grooves -- if they have crisp corners with sharp turns (i.e, there hasn't been a lot of swarf in them), then it's a pretty good sign that the machine hasn't seen a lot of use. Again, hard to tell from the pictures, but those oil grooves look pretty nice...

tattoomike68
10-29-2007, 10:53 PM
In college our professor had us hacksaw a part, file it square and scrape it flat and was a super nit picker.We punched a time card at that class and it was like a job. (kind of:/)

My point is that the professor made scraping part of his intro to machining class. Its cool I learned about scaping even if It was not great.

All Vo Tech professors should all be like the professor I had.