Adding .002 layer to cast iron?
 

I have a lathe bed that is perfect, .0001 except for right at the head stock in a 2" area right by the chuck it drops off about .002 so if I wanted to machine something right next to the chuck it would be off.

Is there anyway to build up the V ways in this small area? I dont want to take it anywhere I want to do it in place. Hard chrome? anodizing? I am using Moglice on the saddle but that only works if it .030 thick or more.

Thanks
Craig

:D
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Sorry, I just couldn't help myself.

There are companies that can spray arc, ( thermal spraying) try calling one of those and see what they can do. It would have to be scraped or ground true afterwords.

How large is the Lathe? From what I remember of chromed ways they had problems, some Bridgeport mills had chrome ways, anodize that is only on aluminium as far as I know.

Its a southbend heavy 10 with a 4 foot bed the total area would only be about 6 sq inches if that.

What are the bearing coatings guys are using on motors? I even thought about powder coating we have a food grade coating that is very slippery.

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I think they use thermal spray to build up most shafts. If they are not hardened probably better to just have them re scraped or ground.

Search turcite, bearing material used on machine ways.

Don’t think so. My Dad has a similar lathe. I suspect a nice milling pass on the high part is a better solution

Old school way would be to scrape the ways flat with a Carbide blade hand scraper

DFL is only about .0003" thick once you burnish it.

Lookup brush plating (plating in localized area)

What are those flat head machine screws holding? Have never seen fasteners there on a lathe,If that section is removable send it out to be ground.

I would shim the area beneath the worn area between the screws and see if that compensates for the drop, you might have to use a tapered shim

Scraping the ways is how it is done. abom79 and keith rucker are doing a class right now in Florida. here is a link to the first part

https://www.youtube.com/watch?v=4sZm6A5svzM

Those hold the main carriage rack to underside of bed.

I think what you are looking for is something called spray transfer welding. It can be used to build up a surface in small increments.

Do keep in mind however that post welding you can't only machine a small section of the ways and would need to have the ways re-machined in their entirety to retain accuracy. You may then as well forgo the welding and just have the ways and gibbs machined, ground and scraped in.

There are pro's and cons to chroming of ways. I am a stickler for scraping as it provides you with vastly superior lubrication, though it is not as durable as chrome.

Certainly not a bad idea, though the small amount by which it is out might make shimming a tad difficult. As shimming is a heck of a lot cheaper than welding and machining this might well be worth your while to begin with.

Yep, some Bridgeport mills have chromed ways, and anodizing is aluminium only.

Though the evidence I have come across is only anecdotal, I believe that scraped cast iron is better for accuracy and provides for better lubrication, as chrome does not have the required surface porosity to retain as much oil as a scraped cast iron surface.

Oh, I second the reference to Abom79 on YouTube. Awesome down to earth guy, and as hobby machinist I love his content. He has a few episodes dedicated to scraping cast iron surfaces that you might find interesting.