Workpiece larger than machine tool

A casting for a conventional design of 1/2 ton capacity arbor press was machined 1/8 inch on a 2 x 10 inch side for a metal removal of less than 2.5 cu in. An open work envelope was configured on a Smithy Super Shop using the saw table and fence to guide the work. The cutter was a 2.5 inch dovetail milling cutter with 1 inch center hole and keyway. The cutter was adapted to the drive with a 1/2 inch shank jeweler's saw holder with 1/2, 5/8, 3/4, and 1 inch ring mandrels supported by a spring, held without the included top cap, and with a purpose made double bevel washer and a M8x1.25 socket flat head machine screw. The base of the casting was leveled by rubbing with a

12 inch sanding disc by hand, using 120 grit Al2O3 abrasive paper, to prevent rocking which stalled the cut several times without damage to the machine.

The passive voice was used because I feel like I've been through a time machine to the 1700s when all of this was done routinely. Pip pip, and all that.

So I figured I'd better tell somebody because this moves the machine tool self-reproduction problem into the international standards segment of development. The question of whether a machine fit can be made on a part larger than the machine tool it is made with is

*resolved* by this constructive proof; this casting could have been seven feet long, and with a few low-wage helpers, would have been machined to the same precision. Remember, the first postulate of machine tool self-reproduction is "We are universal, we define universality, and we self-reproduce." The second is "To make one of anything, you need two of everything". (Except the furnace and forge)

It can be done!

Douglas (Dana) Goncz Replikon Research Seven Corners, VA 22044-0394


Phase Relationships in the Standardization Process. James Gosling. August, 1990.

Reply to
The Dougster
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What do you have to measure the accuracy of the machined surface? I think the ultimate limit is your ability to measure, not the machine's ability to cut.


Reply to
Jim Wilkins

Yes, 'twas ever thus. But ya gotta understand this was *hand fed* taking off only a couple mils, no feedscrew, no vise, no ways, direct contact of work to table, just like ripping a board.

A granite plate 12x18x3 inches, a 12 inch height gage, and a 0.030 range indicator are right here at the desk. I am working both sides of the piece; that improves the stability greatly. There's also a trick of putting an interposing plate under the work as a "carriage" and having *precisely* three equal thickness feet under that. Kinematically nonredundant. Got 5 pieces 36 x 11 x 3/8 glass plate in the patio for that sort of thing, and plenty of Absolute Black tile from Home Depot should it have to look good later.

*Beautiful* surface finish on that part. But...

Something bad happened. :(

I got so excited at the success I started clearing away tools and setting up lighting for filming it. Just one last demo cut, I told myself, for posterity. (YouTube, and INA) Then I had to go and polish the damn fence and table with an abrasive sponge to make them purty.

Four stiches, 800 mg of ibuprofen, and a tasty Chicken Club sandwich from Wendy's later, here I am writing about it. The shop door is shut. No filming for at least a day, maybe ten. I needed the medical grade

72% cacao Ghirardelli to blow the adrenaline out of me, too. I'm wondering how much it's all going to cost me.

I polished to close to the (non-rotating but still wicked sharp) cutter. That's all. A moment of inattention. Damn. 4x4 gauze and a stress ball all the way to the ER. A really wicked gash across that fat muscle at the palm side base of the thumb.

Learned me good, that one did. What goes up....

Douglas (Dana) "Ten Digits" Goncz

Reply to
The Dougster

Er, 1/8 from both side, more like .032 from the side closest to the ram centerline, and the rest from the other side. The nearer side never completely cleaned up (maybe 25% plus), but after only a few cuts of 0.005 to .003 inches provided the stability against the fence for the farther side to clean up to 95% with a uniform finish. The sides are about 4.5 mm thick so that's a lot lost from the farther side.

It's to be filled with epoxy concrete when final. Two brass tubes for the 1/2 inch holding bolts will keep the grout out. It bolts on a board for use on the floor with one hand on the lever, and the other hammering the ram when needed. The current application is squeezing

1/2 OD x 1/16 wall steel tube to flat ends to mount binding posts for a hot wire bender made from a desk lamp and a triac dimmer.

Cutting 60 sfpm is ok, but at the risk of tool wear, I increased to up to 250 sfpm to get the finish at about 0.002 depth of cut, and was careful to blow the graphite away from me with the old blow-pipe puffed-cheeks method.


Reply to
The Dougster

Hey Doug,


OOOUUUCCCCHHHH. Get well quick. Lady next door whacked her knuckles last week, not with a hammer, but with a chain saw! 50 stitches.

So, just removing inattention from the shop doesn't fix the problem. It's outside too.

Brian Lawson, Bothwell, Ontario. the URL for the Youtube (and whatever " INA " is).

Reply to
Brian Lawson

Not so much Ouch as Yikes; more shock value than pain.

Trouble with converter for video. AVS Convert. It works, but they want to sell me a license for *all* their software, to remove the watermark imposed by *this* product. Any suggestions?

By the way, within one hour of playing your last YouTube video, "video [1}.flv" remains in cache. After that, it expires and is removed automatically. View the cache, copy that file elsewhere before it disapears, and convert, and you've snagged it; it's yours forever. It's also overwritten by the next YouTube video you play, so one at a time....

My fave is "Ridicuously Hot Latina Girl Dancing (not Asian)". Yowza!


Reply to
The Dougster

(more snipped by Doug)

Still trying to convert video. My LinkedIn aks "What are you working on now?", Twitter-style. My answer "Recovering from photographing a universal wood and metal cutting machine tool cutting cast iron in an open work envelope, flatness 0.001 on 2 x 10 in." Hah!

The Super Shop is still set up for the cut. My Canon S110 will do AVI. That is an option.

Doug "Hand Bound"

Reply to
The Dougster

formatting link
There ya go. Best I can do right now, a free converter and ratty audio.


Reply to
The Dougster

"The URL contained a malformed video ID. "

so I don't see anything. Try agin for me please.


Reply to
Brian Lawson

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