Need to order some turcite

cathead

cathead

CATWERKS LTD
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In my spare time I have been scraping the ways on my Springfield lathe. I'm to the point where I need to order some Turcite to shim up
the carriage. I see the rack gear has been shimmed about a millimeter so am considering ordering some PTFE Turcite 1.2MM thick to
keep everything in perspective. I'm wondering if that is enough thickness or am I better off getting a thicker piece and scraping it to fit.
I can't see where that is so critical as long as the rack and gear are well fitted. Maybe someone out in machine land has some experience
in this.
 
My instinct is saying to me, use it as thin as possible, consistent with building up as much as you need, plus a little to allow for scraping. I suppose it does not matter much, because the Turcite is not going to deform under such low pressure spread over ways contact area, even if you had it a bit thicker.

If I understand this correctly, the rack gear has been shimmed about 1mm, which implies either that is what it took to have it mate with the pinion correctly when it was made, or some scraping, or maybe a regrind has happened before.

More important is what happens to get the leadscrew to be correct. I suppose it is possible for whole leadscrews (with gearboxes?), and their passive ends, to move up and down, or perhaps alternatively, some modification to the half-nut assembly, to make up for changes in the carriage height on top of turcite.

1.2mm is 0.047". That's thick, but perhaps not so much that other stuff cannot be tweaked to accommodate it. Reading from other posts by folk who have used Turcite for a restoration upgrade, I think they choose a bit thicker, and deliberately mill or grind the ways (or the carriage ways) back most of that thickness dimension before they glue it on, such that the Turcite surface ends up with a little excess to allow for scraping back to the final dimension.
 
The lead screw looks a hair low so that is why I'm thinking a little up cushion might be in order. I'm hoping to
just apply the Turcite and not have to mill or scrape on it.
 
Set your saddle up with bshims until everything is where it needs to be and measure the shims
I buy enough material that I have something to scrape to get not only alignment but enough bearing.
Measure twice cut once.
How big of strips do you need?
 
sdelivery,

Now that is a great idea! The strips need to be somewhere in the vicinity of two feet. I havn't measured the saddle yet.
I will work on it today and hopefully have a better idea of my needs. Thanks for the input.

Edit: The saddle measures about 20 inches wide.
 
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Richard King has offered to supply Turcite to members here in the past, maybe ask him?

I think scraping Turcite is mandatory, according to my research. Looks straightforward enough...

Post your progress on the rebuild, I like to see this kind of work done!
 
This is a work on when I feel like it project so it will take a while yet. I'm using the lathe in the process and learning as I go.
I'm using dial indicators against a reference and using a home made scraper with a carbide tip. Basically I'm removing
the material that I can verify that needs to be removed. Later I will have to get a decent straight edge and bluing to finish up.
I have an 18x24 granite surface plate so may be able to get a rough cast iron straight edge and flatten it out.

Several years ago I made a strait edge using steel and scraped it true. I havn't checked it lately to see how flat it might be now.
It might be usable and maybe not. I know that cast iron is more stable but had to see how steel would work out over time.
P1000866.JPGThe jury its still out on this piece.

P1000839.JPGThis is my home made scraper with replaceable carbide tip and handle from an old jig saw.

I will make another post when I have made a significant milestone. It's winter up here and the ambient shop temperature
drops off in the cold. Presently the shop temperature stays at 55 to 60 F. without turning on my forced air blowers that
extract heat from circulating boiler water. It gets to the point where I would need to fire harder in the boiler to keep the
shop at 72 F. I added a Modine forced air heater in the water loop so I can have it warm if I need to at the expense of
the woodpile.:concerned:
 
I'm working up to doing the same thing with my Monarch 12"CK, so I'll be watching your progress. I've just finished up scraping in an 18" straight edge to use as a reference. I'll be milling out a bit from the carriage to allow for the turcite buildup. Haven't gotten to the point of making measurements and figuring thicknesses.
 
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