The Home Machinist!

I've gotten a bit flustered over this since getting it close seemed too easy...

I'm using a standard dial indicator in the spindle on an arm that is about 5 inches out from center (sweeps about a 10 inch circle).

I initially measured that the left to right variance was ~ 50 thou, so inserted pieces of sheet metal under the right side and measured the following 4 points:

0.0015 - 0.0020
0.000 - 0.0015

OK, this took a while and my sheet metal pieces are straight - they do not contour the bolts - so should I do a better job and make larger shims? I'm just concerned that it may shift or stress the mounting.

_________________
Standards are so important that everyone must have their own...
Logan 10x24 Lathe, RF-30 Mill, 20 Ton Press
Disclaimer: I'm just a guy with a few machines...

I supposed it would depend on how heavy the castings are, and their resistance to flexing. Certainly it does not need to be fully supported (a lot of lathe headstocks are supported along two edges). I think it would be better to have a U shaped shim or washers, but to be any better than what you have, they would need to be tapered. What you want is support all around the bolt, as that is where the pressure will be.

If the castings are heavy enough to have minimal flex, it will be fine as is. Certainly you can try it and see if it works for you as is.

Wayne

I also wanted to confirm that I will not get into a tail chasing exercise. It was warm last night when I left the machine set up with the indicator.

This morning I read it again and I can see how much the change in temperature affected the machine:

0.003 - 0.000
0.002 - 0.001

_________________
Standards are so important that everyone must have their own...
Logan 10x24 Lathe, RF-30 Mill, 20 Ton Press
Disclaimer: I'm just a guy with a few machines...

Hi. You probably already know this but there is a certain amount of flex depending on what you use it for. I have an older model heavy 2hp and the octtop base and it isn't as stable perhaps. I fretted with getting the DI just right but it was unloaded. It's interesting to watch the deflection under downfeed side pressure and maybe leave some error bias that way.

many will chase after me but before i go too much further i would explore articles on adding mass to the machine and this will help dampen vibration and limit flexing perhaps concreting the base table top and inner collum as ideas. i have seen others use epoxy and lead to do the same thing.

True. I don't see anyone chasing after you except to explain their own reasons for Not doing that. In my case it was basement steps and the eventuality of removal. That's going to be work.