Cataract swirl finish scraping?

[Billtodd]

I've just acquired an old and unusual lathe (unknown 164 on Tony's site http://www.lathes.co.uk/unknown164/). On close inspection of the photos, I've found that the cross slide is a pre 1920 Cateract.

The line drawings of the slide seem to show a swirl finish (jeweling? ) , that I initially assumed would be produced by rotating abrasive. However, another photo shows the arse-end of a Cataract bed which shows it to be altogether something different : somekind of magic scaping!

Does anyone know how this was produced?

 

[Tom A]

Mine, which is a 1939, has a pattern that looks like little crescent moons or fish scales.

 

[trevj]

The scraping appears to have been formed by a straight cutting edge, pivoted in the middle to form that shape.
Kinda hard to tell on the print, but it does appear to my eye that the pattern on the cross slide may be made up of two such scrapes, across the same center point.

 

[Richard King]

That's what is called the Butterfly scraping. It is for cosmetics. Much like Bridgeport does on the top of the table doing 1/2 moon flaking. I have tried to do it a few times by using a flat ground scraping blade and you push down and a slight tipping to the left moving the back of the handle to the left to cut into the iron (left wing) and then rock it to the right and turn the blade to cut the right side (wing). I didn't try long as it must be as hard to learn 1/2 moon flaking by hand. That's what I do to cosmetic a surface or square cut in diagonal lines.

 

[Billtodd]

Crikey Richard, if you can't do it , what hope us mortals ;⁠-⁠)

 

[L Vanice]

I have had Cataract lathes and mills since 1978. I made a square ended flat scraper with the correct width and quickly figured out how to duplicate the butterfly effect. Having the tool is 90% of the trick. Knowing what the original factory scraping looks like is another 10%. Doing it is dead simple. I do not make a habit of scraping everything I own, though. Knowing how is sufficient.

Many years ago two brothers who claimed to be machine rebuilders bought an old Cataract lathe from me. I visited their shop a while later and they had hand scraped every visible flat surface of the lathe and slide rest. Spotting mind you, nothing like the way Hardinge did it. I thought it looked disgusting. They had it sitting just inside their front door to impress potential customers with their prowess. I suggested I could help with replacing the worn out slide rest feed screws and nuts, since I had NOS parts and original square thread taps. They said they just saw cut the nuts and hammered them together to tighten up the backlash. I think they soon went out of the machine tool business and ended up repairing garage doors.

Larry

 

[michiganbuck]

we used to make that pattern with a wood dowel charged with Colver compound.

 

[Billtodd]

So, Richard, Larry,

Is each pie segment produced in one action and the tool repositioned and aligned for the opposing segment? Or can the tool make both cuts in a fore and aft motion?

 

[Billtodd]

we used to make that pattern with a wood dowel charged with Colver compound.

Yes that is what I believe is called jewelling, but the pattern Cataract used is a scape action.

 

[Mark Rand]

Connelly mentions it in his book, with a description of the technique.

 

[MrStretch]

I wonder how much of the decorative spotting in the old catalogs is the illustrator tarting things up a bit.

 

[Joe Michaels]

The pattern shown in the picture is sometimes called "engine turning". It was also known as an "apprentice finish". This latter was a somewhat derisive term used by old-timers to describe efforts by apprentices to 'dress up' what might be mediocre work.

To support what Billtodd posted: I learned to make the 'engine turned finish' when I was a teenager. We used a hardwood dowel chucked in a drill press, or a piece of aluminum or yellow brass rod, charged with lapping compound. This produced polished circles. The trick was to get a uniform pattern of overlapped polished circles. I remember once, finishing up a job in the form of a piece of tooling to be used in a machine shop where I was working. I thought I was hot stuff, finishing it by drawfiling, breaking all the sharp edges with a neat small filed chamfer, and then polishing with emery cloth wrapped on my file. I should have stopped there. Instead, I engine turned the outer surfaces. I caught hell for it. The older journeymen and the foreman hollered that I was working in a machine shop, not a "Canal Street jeweler's" (jewelers along NYC's Canal Street were not held in the highest regard, to be polite). They were also annoyed that I had spent shop time putting on that engine turned finish, and let me know about that as well. I will admit to occasionally putting the engine turned finish on some jobs coming out of my own shop, using an aluminum rod as the lap and "Clover" lapping compound. The 'plates' in some pocket watch movements were also finished by 'jewelling', and maybe that is where the term 'jewelling' for this type of finish comes from.

A closer look at the picture of the compound slide shows this 'engine turned finish' is applied to non-bearing surfaces, rather than to the actual sliding/contact surfaces.

I recall gunsmiths as well as firearms manufacturers would sometimes offer what they called a "jewelled finish" on rifle bolts. This was an engine turned finish done with a very small diameter lap. Another example would be the aluminum cowling on Lindbergh's plane "The Spirit of St Louis", as well as automobile instrument panels in the 30's. On aluminum, this finish can be gotten using a fine wire brush chucked in a drill press, and nowadays, is often done on aluminum using a die grinder with "Scotchbrite" discs.

 

[SIP6A]

I I think they soon went out of the machine tool business and ended up repairing garage doors.

Larry

Well Larry they found there calling.

 

[Tyrone Shoelaces]

I used a piece of ” Tufnell “rod about 5/8” in dia with a hacksaw slot cut in the bottom. I folded and doubled a small piece of emery cloth into the slot. Just light dabs with the rod in a drill press did the trick. I have done the same job wits the rod and grinding paste.

Regards Tyrone.

 

[Screwmachine]

Hardinge very specifically did this finish with flat scrapers, as noted in Connelly and several times in this thread. It may resemble finishes done with dowels and abrasive or whatever, but is quite different.

 

[jim rozen]

Not all hardinge toolmakers compounds had the beauty treatment. I think they reserved those for their catalogs. Notice the conspicous absence of fancy flaking on this NOS hardinge slide:

 

[old_dave]

Hardinge very specifically did this finish with flat scrapers, as noted in Connelly and several times in this thread. It may resemble finishes done with dowels and abrasive or whatever, but is quite different.

One term Connelly uses for this is "Butterfly Frosting."

He goes on to describe what he calls "circular flaking", the process perhaps most commonly called "engine turning." He says "This type of flaking mark, however, is never found on a piece of high grade machinery. Essentially, it distinguishes the handicraft of the home workshop enthusiast."

I have a hunch Mr. Connelly was hard to get along with...

David

 

[Hobby Shop]

The HS machine shop teacher made us use the jeweling technique on some of our projects by putting a 1/2-3/4” piece of graphite in the drill chuck.

I know one is scraping and the other is cosmetic but it made a similar pattern. It worked great for what it was intended.

 

[L Vanice]

Not all hardinge toolmakers compounds had the beauty treatment. I think they reserved those for their catalogs. Notice the conspicous absence of fancy flaking on this NOS hardinge slide:

That "NOS" Hardinge slide rest has had the tool post T-slot broken out and repaired with screws and steel plates. No telling what else might have been done to it in 100 years.

Larry

 

[IrbyJones]

I have an example of this butterfly pattern on my 1920's Hardinge Cataract toolroom lathe. They only did it on the front of the ways (the second photo has an arrow pointing to where I took the photo), regardless of what the illustration in the catalog shows.

Irby