basic lathe tooling questions for new lathe

[EdK]

(04-03-2012, 01:54 PM)candiamel Wrote: First of all, I’m not very experienced at machining, so I’m looking for really basic guidance to purchase some tooling for my Vectrax 14x40 lathe.

I was thinking about 5/8” tool holders as those will more-or-less line up the carbides with the center of the turning. Though maybe not exactly. I know, I know, I really should get one of those fancy dovetail tool posts but I’m running out of cash!


So, here are my questions:

1. Is there much difference in rigidity or quality of cut from stepping down from a ¾” tool holders to 5/8” due to vibration or flexing?

2. I’m told that CCMT or CCGT bits are the ones of choice for hobbyists like me. Given that, is there any difference in cut quality or should I have any different expectations than the mediocre results that I’m getting from my “TT” triangular cutters?

3. IF there is no difference in cut between a CCMT and a TT, does it make more sense to keep using the TT because of better economy? (you get three cutting surfaces instead of two)

4. What do you suggest for a carbide insert cutoff tool?

5. Can anybody point me to a simple chart that shows approximate turning speeds, feed rates, and cut depth for different materials?
Thanks!
Bob

Bob,

I'm going to give you my 2 cents. Take if for what it's worth.

Being that we have the exact same lathe I think some of what I will say has some small amount of merit based on my experience with the lathe. I'll tackle your questions in order of presentation. The lathe being a Vectrax ( or TurnPro) 14x40 made in Tawian, 2HP motor lathe.

1. On our lathe, no chance in hell you would notice a difference between a 5/8" and 3/4" tool.

2. I think your options for different types of inserts are going to be much greater with the CCMT/CCGT insert versus the TP type of insert. Also, the cost should be cheaper using the CCMT/CCGT insert because they are much more available. TP inserts are not likely to be used by machine shops thus the demand for them is much less than for CCMT/CCGT. As far as the difference in cut quality, you should be able to do better with CCMT inserts because they are available in so many different varieties that you should be able to find one that suites just about any application.

3. See last sentence in reply number 2. But to add to it. you can purchase CCMT insert tool holders that allow you to make use of all four tip. In that case the two tips that are normally not used are used just for roughing cuts.

4. That's a tough one given that you don't have a QCTP. I suck at cutting off and usually resort to a hack saw so I'll defer the answer to those more knowledgeable than me, which are most.

5. Sure can: http://en.wikipedia.org/wiki/Speeds_and_feeds
But be aware that most of those charts are made for production equipment, not hobby equipment. I go by sound and feel and end up going much slower than the charts recommend.

Hope this helps some.

Ed