I've watched a couple of vids but I thought I would ask you guys before I start cutting if there is anything I should watch out for, tricks, tips?
Hey Chris, I guess I should try to answer your question eh..... LOL!
I gotta start by saying that I've yet to see a YouTube video that covers all the bases. A few cover certain aspects well, but nothing I have ever seen covers the subject completely. So you might be better off forgetting what you saw.
I am whipping this together for you before I head out planting my fields today. So it might not be perfect. I will appreciate any feedback from knowledgeable members for any errors I make unintentionally, or anything I missed. It's one thing to write a quick summary and another to actually do it.
Different kinds of lathes use different methods to line things up. Generally, it's done by bending and/or twisting the lathe in various way. Remember that everything is rubber.....
Some lathes have special alignment screws, some use the cabinet feet, some use bed feet, some use shims, and some are not really adjustable without scraping or shims or other more intensive means. In every case, it is an iterative process because most changes affect other changes. If your lathe can be adjusted the following is just a guideline. It is only
my guideline as others may have their own ways of doing it that may or may not be legitimate. The goal of lathe alignment is simply to ensure that your lathe can cut as close to cylindrical concentric (not conical) parts as possible across the length of the bed.
Step 1 - Remove any twist from your bed. This is the step that earned the term "levelling the lathe". You can usually use a precision level to evaluate and eliminate twist. The bed doesn't really have to be level. It just has to have the same "tilt" along its length from end to end. I prefer to put my level on the two way flats using precision blocks not on the V-ways. The top of the v-ways are not always ground consistently. If you can't use flats, then use two v-blocks between the v-ways and the level. Don't use the top of the v-ways unless you have no choice and if so be skeptical. And don't interchange the blocks - the rear block should be the rear block for all measurements, etc.
Step 2 - Align the tailstock up close to the head. I like to use tailstock alignment buttons. You can buy them or make them. Cut the chuck center in place so the center reflects the axis of the spindle and then don't move it. Many guys just use a bar between centers and work toward eliminating taper by centering the tailstock. If you use a long bar, be careful about what you are measuring - see other steps below.
Step 3 - Align your bed. (This assumes your bed isn't badly worn). You can put a known good bar between centers to measure and eliminate bed bend. These included hump back bed, sway back bed, bent in or out bed etc. Bent in or out is not common, nor is it easy to fix. But it's good to know if you have it. The process involves sweeping an indicator along the top and sides of a long perfectly cylindrical test bar held between centers and then evaluating why it deviates, if it does. This is a difficult step because it's so easy to misinterpret what the indicators show. Take your time and do it carefully. Study what you measure and ask yourself why.
Step 4 - Align the axis of the Spindle with the Axis of the bed. You don't want the spindle axis to point up or down or sideways relative to the axis of the bed. Chuck an 8" to 12" piece of schedule 80 pipe with an OD of 1" to 2" in the Jaws of a chuck and try to make sure it is relatively stress free. (note that I am working on longer bars to calculate and negate the effect of gravity, but I'm not ready to share yet. Schedule 40 will work but it doesn't have as much meat to cut with....... and you will probably do a lot of cutting.
Begin by relieving the center of the bar to create a dumbbell. Then "shave" (extremely light cuts) the two end lands very carefully and consistently. You don't want to bend the bar as you cut it. The goal is to align the head with the bed so it makes these two cuts identical both up and down and side to side despite their separation. If you suspect bed wear, you can cut 3 or 4 collars to help quantify the devaluation and wear.
To repeat, this process is iterative. By its very nature you will not likely be able to do this like you make parts. The adjustments affect each other. The ideal alignment for every lathe will be different. However, by doing it, you will come to know what the strengths and weaknesses of your lathes alignment are and you can try to compensate for them as needed.
. Almost anything can make a blank but be aware that stuff like drill rod is neither round or straight - it's centreless ground. It could still work, but you need turn it, not rely on its existing surface.