Scraping Lathe Compound And Cross Slide Order Of Operations

[bkcorwin]

hi everyone. Scraping is going along great and ive been looking for more things to practice on. Im in the market for a new lathe so i figured the cross slide and compound of my 12x36 atlas was a good candidate. They are horribly roughly milled. I have some questions though.

For the compound the slide is longer than the base. Ive got the flat side of the top part coming in nicely. Since the top part is longer its easy to just use it as a master for the lower part of the compound.

On the cross slide the ways are longer than the upper part so i cant just scrape the top and use it as a master. In this case do i just remove the carriage and scrape the ways in to flat independently and use my dti and surface plate to maintain the two ways in the same plane and then use the carriage as a master for the cross slide? Opposite master child relationship tha. I used with the compound.

Thoughts?

 

[loply]

Hey,

For scraping the cross slide, it may not be possible to have it sit flat on your surface plate (depending on the lathes bed), in which case you may actually need to first scrape the topmost clearance surface (above the screw) flat in order to use it as a reference plane. From that surface you can then put a DTI and check the height of the two slideways, to ensure they're equal.

But otherwise, yeah just scrape the two slideways on the carriage flat and to an equal height. You can scrape the base of the cross slide itself off the surface plate, only really the dovetails need to be done by mating the two parts together.

Even the dovetails can be scraped flat using an angled reference if you have one.

When you rescrape the slideways on the carriage make sure to check they are perpendicular to the spindle axis. You can do this by chucking up an indicator arm and indicating a pin on the operator side of the nearest dovetail, then rotate the chuck so that the indicator spins around and indicates off the far side of the dovetail.

You want it to be cutting ever so slightly concave if anything.

Cheers,
Rich

 

[bkcorwin]

Ah, that took a second but now I see. You mean to scrape the first non contact surface on the carriage. That makes sense, then I could use that as my referenec as you say.

luckily, I think I will be able to use the lathe carriage directly on the surface plate, and if not directly on the surface plate I have a couple sets of precision ground busch precision box parallels of about 2"x1"x12" that should be able to replicate the flat ways sufficiently to get it on my surface plate.

Thanks, all good information!

Brian