Two Part Tapered Gib?

[codohundo]

I have a long term goal of building a nice sized vertical mill, 500mm x 300mm x 300mm capacity, about 20" x 12" x 12" for the metric impaired and throughout the design and research phase I've come to the conclusion that I'm going to need to build a crude metal sharper first. I've been designing the metal shaper based loosely on Gingery's but I don't like the Gib setup, I'd rather use a tapered gib, however I'm not sure I can make a good tapered seat for the gib with the tools I have on hand. So I just wanted to float this idea and seek advice from those more experienced than me.

Does the idea of using a split 2 part tapered gib make any sense, ie the gib seat would be true to the slide and two tapered gibs would stack to form a rectangle which can be made thicker or thinner by sliding one past the other, one end would be seated against a stop and the other end could be adjusted with a screw? Or do you think in the long run it'd be better to just try to use a traditional tapered gib and try to make the gib seat angle? I've never heard of this but my exposure is fairly limited.

Background
I have access to a combo lath/mill machine with some tooling, but nothing exotic and basic hand tools
I'm a 100% hobbiest and quite new
I'm aware of how ambitious this project is
I'm not expecting to save any time or money, or gain any reasonable advantages by building my own machine, I'm only doing it to see what I can achieve.

 

[Richard King]

There are several types of gibs. I would think you would be better to have one gib as there is not only side pressure but there is up / down pressure This could make it unstable A shaper produces lots of side torgue. Why re-invent the wheel. If it was a good idea, machine builders would have used that idea for years and I can't say I have ever seen a 2 part tapered gib. I suggest you get this book Machine Tool Recondioning as there is a chapter of gibs. Gibs need to fit with-in .0002" to .0005" so the ways stay stable.

http://www.hobby-machinist.com/show...ng?highlight=machine+tool+reconditioning+book

 

[codohundo]

Wow, I've seen so many posts asking you to weigh in, glad to get a respected opinion right off the bat.

The particular way I'm speaking of will be for the ram itself, it's a box style way so I can't see any loading other than the in plane loading, I'll sketch up a drawing after work to show you exactly what I mean.

The Gingery design calls for a simple straight gib pressed in with screws, which I'm sure would be good enough but I'm confident that a tapered way would be better, the trick for me will be matching the taper so I maintain parallelism, so I was basically looking for a way to make that part easier with a replaceable seat.

I'll be looking into that book, thanks.
Travis

 

[Richard King]

I have discovered in life, if you have an idea and your sure it will work...go for it! Or you will always wonder if it works.
Good Luck, you never know, you may invent a revolutionary gib design. Rich

 

[codohundo]

Since I said I'd sketch it up, here is the basic idea:

The part on the right is the ram, it has 3 running surfaces on each side the part floating above would bolt down with shims to fit. There would be a similar way on the other side of the ram, minus the gib. This is basically the Gingery design with the exception of the gib, in the original design it would be a single rectangular plate pressed in from the back with multiple screws. In this design it'd be match tapered gibs that can be set in position. The retention mechanism hasn't really been thought out that much yet but you get the idea.

The main advantage (I hope for) here is that I can machine the two gibs at the same time to produce an identical angle, scrape or grind them true, and, so long as everything else is true, I can adjust the gib clearance precisely, maintain parallelism, and the gibs are fully supported as opposed to just having point supports periodically.

Speaking of scraping, is it inappropriate to ask, in this forum, if there will be another scraping class in the west this year, I can't make the May class.

Thanks,
Travis

 

[Richard King]

It just seems to be a lot of extra work. I would also make the adjusting bracket that holds the gib screws attach to the whole gib or at least centered. The gibs should also have a way wiper on them to protect the ways from dirt.
Cool sketch software Rich

 

[codohundo]

I don't mind the extra work, like you said, I'll probably always wonder if I don't try. Good catch on the wiper, I hadn't really started designing it yet, this is just a rough sketch, but that had fallen off of my radar. The sketch was done in Trimble (formerly Google) Sketchup. I do all my 3d printer, laser cutter, woodworking, etc. drafting in it. it's no Autocad or Solidworks but the price is right.

Travis.