Round column mill guide to maintain alignment

[slow-poke]

I have an old LC30 round column mill that I want to add some sort of guide to allow raising the head without loosing alignment. Goal would to be within +/- 0.002”

I watched a couple of videos and it seems like one of the problems with this approach is the rigidity of the rod.

Has anyone found a better approach?

One thought that came to mind is finding an old dumpster type mini lathe and using the bed and carriage (obviously cut and milled), and flipped to run up and down.

Used wood lathes are cheap and plentiful on Kijiji however I’m not sure how well the carriage is aligned with the bed on these wood lathes?
Thoughts?

 

[T Bredehoft]

Someone on here showed us what he'd done years ago. He had a 1" steel rod and bearings mounted on the back of the column, attached to the column at the top and the base at the bottom, with the head captive to the bearing, claimed it repeated usably when moving the head up or down. It was mounted so it could be rotated, allowing the head to move sideways if needed.

 

[rodm1]

You might be able to use the rack and make kind of a linear bearing setup not shire if possible but someday may give it a shot.

 

[Winegrower]

Used wood lathes are cheap and plentiful on Kijiji however I’m not sure how well the carriage is aligned with the bed on these wood lathes?

My wood lathe and every wood lathe I’ve seen have a tool rest rather than a carriage. There is no alignment provided as they are loose and can be clamped anywhere along the bed.

 

[DavidR8]

@slow-poke This is what I did. Works fantastic.

RF30 alignment guide build

Inspired by @Gravydog excellent build I decided to embark on my own build. Picked up a slice of 6” diameter 6061 and faced it off. I have to say that watching the cutter slowly make its way across the work is somewhat mesmerizing. The stock was too big to use my toolpost indicator holder to...

www.hobby-machinist.com

 

[premodern]

Why not just use this simple method of realigning?

~Hans

 

[epanzella]

The farther the rod is from the column the more consistant it will be.

 

[Mitch Alsup]

I watched both films making a sliding rod to keep the head aligned.

It seems to me that the sides of the vertical rack would be a lot easier to use as a reference surface;
Basically you put two shoulders that use both sides of the rack (one adjustable--like a gib) and use a part that is already stiff to the column.

So, is that rack a) stiff to the column ? and b) straight enough to use as a reference surface ?

 

[arty1]

Here's what I did when I had my round column mill. Wasn't perfect, it was still off by a few thou. Not being consistent when tightening/re-tightening the head bolts after moving the head up/down would be enough to throw off alignment even with this rod/linear bearing setup. I've recently sold this mill and have a square column mill on order.