Practice scraping

[Erik Brewster]

Whatever you do, make sure the oil gets there. Your oiler doesn't need to be gold plated. It just needs to get oil where it needs to go.

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You should take it to work and fly cut or mill the ways first. Trying to scrape that would take lots of hours even if you had a Biax Power Scraper.

The man speaks the truth. I have been scraping a drill press table for the heck of it. It was only out a few thou, but that is ~4 hours of rough scraping with a Biax to get it flat. And that is an easier shape to scrape than a mill way.

 

[astjp2]

That's Nasty.

You should take it to work and fly cut or mill the ways first. Trying to scrape that would take lots of hours even if you had a Biax Power Scraper. If the machine you using to fly cut is decent you could probably hold .001". Then scrape off the machine marks to give it a smooth surface and some oil pockets. I would also be sure the ways are getting lots of way lube too with a gravity feed oil cup or a pressure pump lube like a BiJur or LubeUSA. Rich

I had to think about this, do I just mill the flat surfaces or do I do inside the dovetails also?

 

[Richard King]

I had to think about this, do I just mill the flat surfaces or do I do inside the dovetails also?

Both..the easiest way to do the doves is to use a dovetail cutter. If you can't afford one you could tilt the head on a Bridgeport type mill and carefully indicate in the angle of the dove within. 0002". If you have never used a fly cutter ànd you have some experienced machinist's in the shop ask them to help. On the Chinese mills I've seen the base bosses are not parallel with the top and I've seen where only 3 of the 4 feet touch, so I would set it on a surface plate and test it. The one we machined in the CA class we started by machining the bottom first off the bad ways. The flipped over and cut the top. Scroll down the list of thread and look for the CA class and read it. Mel had the base and we took pictures of it on the mill and fly cutting. Rich

PS : check on the thread above CA class almost full started by Mel..he owns the Chinese mills mill i spoke of.

 

[astjp2]

I went to measure the table, it was .008 tall in the middle, so I ground the top on a surface grinderand measured the distance between the ways and the fresh ground top, it is within .0018 from middle to end and .0012 from side to side. The gibs are within .0015 parallel with .050 ground dowels between them. Now I just need to get it on the saddle and make sure it is spotless before lube with way oil. Scraping will come later, this is to get nice surfaces to work with.

I took .018 off the top of the table and it was parallel within the first .006ish but I wanted to clean up most of the drill and hammer marks, the additional .012 cleaned it up real nice. I used a stone to break the edges, now onto another part tomarrow if I can get to it. Tim

Both..the easiest way to do the doves is to use a dovetail cutter. If you can't afford one you could tilt the head on a Bridgeport type mill and carefully indicate in the angle of the dove within. 0002". If you have never used a fly cutter ànd you have some experienced machinist's in the shop ask them to help. On the Chinese mills I've seen the base bosses are not parallel with the top and I've seen where only 3 of the 4 feet touch, so I would set it on a surface plate and test it. The one we machined in the CA class we started by machining the bottom first off the bad ways. The flipped over and cut the top. Scroll down the list of thread and look for the CA class and read it. Mel had the base and we took pictures of it on the mill and fly cutting. Rich

PS : check on the thread above CA class almost full started by Mel..he owns the Chinese mills mill i spoke of.

 

[astjp2]

This is the saddle before grinding, it looks pretty rough but cleaned up nicely with about a total of .012 from each side. I found that the surface grinder Y axis is off by .0017 down ward slope, so I used a .0015 shim and got it within .0002 from side to side. The center of the table is low by .0012 because the mag chuck did not support the ends. Overall I think I have a good starting point for scraping. Tim