Epoxy granite metal lathe - videos

[tonyfoale]

I'll be the first to admit I never watch anyone's videos to their entirety if the video is longer than half a minute. Additionally, I hardly ever put on my head [phones to listen to their dialog, consequentially I did not note anything about expansion issues and wouldn't think there could be much change within the normal range of temperature changes in most shops. where the climate could be controlled within 10 to 20 degrees one way or another, I know where there is a huge lathe made out of concrete with iron rails for the ways that is over 100 years old it is used to make 100 ft long shafts for hydroelectric turbines
I did notice in one of his videos where he used tapered roller bearings for the spindle bearings. A lot of lathes used those but nearly all of them that are of any quality also have an angular contact ball bearing next to the larger roller bearing at the chuck end of the spindle

I am normally like you regarding watching the videos posted on HMT forum but this one caught my attention because of the apparent similarity to what I plan for my surface grinder, and I watched by jumping along until there was a change in the picture. i did happen upon a section where he remeasured the alignment of the slides and there was a 5 thou vertical bend which he related to a small temperature change between that measurement and the same measurement when he aligned the slides. He then put a sample of epoxy granite in a freezer and measured it cold and room temperature and calculated the coefficient. I forget the value but it was much higher than steel, this can only occur if his resin content was excessive. It is a pity because it is one of the nicest lathe builds that I have seen here in stark contrast to a few of the recent offerings which are just plain crap.

[tonyfoale]

i just noticed that he used 11% epoxy but that was by weight, that is a big difference to 11% by volume and confirms my thoughts about it being resin rich.

[Frank S]

I am normally like you regarding watching the videos posted on HMT forum but this one caught my attention because of the apparent similarity to what I plan for my surface grinder, and I watched by jumping along until there was a change in the picture. i did happen upon a section where he remeasured the alignment of the slides and there was a 5 thou vertical bend which he related to a small temperature change between that measurement and the same measurement when he aligned the slides. He then put a sample of epoxy granite in a freezer and measured it cold and room temperature and calculated the coefficient. I forget the value but it was much higher than steel, this can only occur if his resin content was excessive. It is a pity because it is one of the nicest lathe builds that I have seen here in stark contrast to a few of the recent offerings which are just plain crap.

That makes me wonder if it might not have been fully cured or if it should have been aged for a while even after curing before further processing.
I'm not all that familiar the granite epoxy composite, but I have had fiberglass repairs creep due to shrinkage after they aged a while