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Restoring and CNC converting Siber Hefner RB1

abakker

Plastic
Joined
May 30, 2017
Location
SF, CA
Here’s the short story: I have a Bridgeport knee mill that I converted to CNC a few years ago. I’ve since acknowledged to myself that everyone who said that knee mills are bad CNCs were right, and I set out to find a better option.

Long and short, I found a siber hegner RB1 for cheap, and bought it.

The situation is this:
1. I’m a hobby guy, holding .001 is definitely good enough. I don’t need to make perfect parts and I know when to hire pros.
2. I don’t expect this to be my be all end all machine, but it is a step in the right direction. It doesn’t have to be the last thing I ever do.
3. I want to do a good job, but I don’t want to be ridiculous. It’s a used bed mill with dovetail ways. I don’t need 400IPM rapids 24/7.

So, here is my conundrum. The mill I bought was in an auto shop where it was used as a drill press with a fancy table. The head was dead. I guess the vari speed bushings died and then they ran the motor with the rattle until the motor shaft has .375” of wear on one side. Yes, you read right.

The ways are scratched - mostly the upward facing ways on the bed.

The upward facing ways are hardened. The column ways are hardened, and the top of the saddle is hardened.

The gibs were never scraped and the dovetails were never scraped.

I tore the whole mill apart, and soda blasted all the parts clean of goo, schmoo, and crust. I then inspected.

Essentially, the ways on the vertical y axis and the column ways have hardened surfaces that are badly scratched. Other than that, everything seems flat to +/- .0015. Before tear down, things moved freely and nicely.

I took the saddle off, stoned the surfaces that mate with the scratched bed ways and then scraped it in. I’m going to have a local shop dust the top of the saddle to ensure it is cleaned up nicely.

Here’s the questions

1. Should I worry about about scraping the ways on the table? They were ground and are in great shape, but have no oil grooves, scraping, or flaking.
2. How should I treat the scratches in the y ways on the bed? A carbide scraper won’t bite, and my precision stones are going to be inadequate to just buff high spots.
 

Richard King

Diamond
Joined
Jul 12, 2005
Location
Cottage Grove, MN 55016
There isn't much more you can do to hardened ways unless you want to have them ground. A picture of the saddle top and bottom would be nice too. The scores are from lack of lube. You could leave it or mill the saddle and apply some Turcite. Make sure you clean and repair the lube system and as you said add a few more oil grooves. You may want to use a round stone and make sure the scores are low say .001". Add some new wipers too and a cover on the spindle side. Is it a horizontal or vertical mill? The one photo of the Bridgeport saddle - it's high in the middle. It seems like you know the answers and are fishing more then asking
 

abakker

Plastic
Joined
May 30, 2017
Location
SF, CA
That’s probably fair. I guess I was fishing a bit for a solution I hadn’t heard of. There’s nothing to fill in scoring, right?

It’s a vertical mill - essentially a Bridgeport clone, but in bed mill format. All the photos from that album are from this mill.

Here are my basic questions:
1. For the scored ways - if I thoroughly deburr them, and fix the mating surfaces, is there any reason I can’t just live with them that way? Do I fill the grooves with something?
2. For the dovetails and gibs which were never scraped, should I scrape them? Presumably these surfaces matter less than the ways, but scraping should increase rigidity and decrease abnormal wear?
3. For the table, the downward facing ways have no oil grooves and we’re not scraped. The mating surface on the saddle has oil grooves. Should I add flaking on the table ways? Should I scrape for bearing? What was customary on bridgeports or other manual mills?

Thanks for the help!
 








 
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