basic lathe tooling questions for new lathe

[candiamel]

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

[TOM REED]

(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

oN MY LATHE 12x40 advertised size I dont see any real difference in cut quality. I have a QCTP wedge style I bought from CEDCO and am happy with that, I have bought
some 1.5 inch shank larger toolholders that I have now cut dovetails on to use for the QCTP and use the large carbides I have and am also happy with these. I have been using HSS cutoff toolholder but recently bought a carbide cutoff tool 9/16 that was made in Korea with 10 inserts for about $80.00. That was a waste of money, I guess I should have sprung for a Sandvic as they say they are the best. I have lots of HSS tooling for a rocker toolpost so will have to make a lantern toolpost for my lathe. I almost think that the old rocker and HSS tools are the best for most of the thing I do other than the heavy cuts which mine does extremely well with carbides. tom

My experience level I would say is quite amateur with most of it 30 yrs ago in the gunsmithing end, back then I would have died to have a lathe the quality of my new import made by SIEG.

check out chathamtool.com he has a very nice set of plans for a turret toolpost that looks excellent, I am going to make one of these which will also improve my skill level. These plans are selling on e-bay for under $15.00 funny I just checked to see if I could get to the website for this and his does not come up so you will have to search e-bay to find them. tom

[DaveH]

Hello Bob and welcome to MetalworkingFun

My answer to Q1. I doubt if any noticeable difference in the home workshop.

My answer to Q2 & Q3. Again probably no noticeable difference, go with the most cost effective.

Questions 4 & 5 I will have to think about them

Hang about Bob, others may have a different opinion

DaveH

[doubleboost]

(04-03-2012, 02:46 PM)DaveH Wrote: Hello Bob and welcome to MetalworkingFun

My answer to Q1. I doubt if any noticeable difference in the home workshop.

My answer to Q2 & Q3. Again probably no noticeable difference, go with the most cost effective.

Questions 4 & 5 I will have to think about them

Hang about Bob, others may have a different opinion

DaveH

Hi
Bob
Unless you are pushing things to the limit you will not notice any differance with the smaller tool size
I use a piston type tool holder and i am very happy with it
As far as parting tools go this is what i use
http://www.ebay.co.uk/itm/GLANZE-CLAMP-T...46021476e0
I use the cheapest tips i can find
Mu previous lathe was fairly large (colchester Bantam).
My current lathe is much smaller so i modified my large tooling to fit , by milling a dove tail in them .
They go directly on to the tool post without a holder.



As far as tips go i would just use the most economical
There are loads of speed & feed charts on the net.
But for home work i would just experiment.
Dont forget carbide inserts like to be worked hard
John

[PixMan]

Depending upon the size and HP of your lathe, you may or may not see a difference in performance of 5/8" or 3/4" shank tooling. It would take 5HP or more to see the difference as you cut, other than that the 3/4" by nature has better vibration damping qualities because there's just no substitute for mass.

I see you're in NH, so don't bother going looking specifically for a Glanze parting tool holder here. I can help you with tools selection and sourcing as I'm local to you and know some great sources for new, used and cheap tooling. Mayhem has been shopping here with me and can attest to that.

What lathe do you have and what the heck are "TT" inserts? I'm in carbide insert tooling as part of my livelihood, and that's a proprietary designation if ever I heard one. In the lathe tools, there's no need to go proprietary in anything other than parting off.

John is showing a triangular negative rake toolholder and insert in his photos above. That TNMG332 insert can use up some HP if pushed. The fairly wide GTN parting insert shown is fairly common, but there are other styles available that could be thinner and require less HP.

Give me some more info and I can help you more. Pictures always help.

Ken

[stevec]

(04-03-2012, 04:04 PM)doubleboost Wrote:

(04-03-2012, 02:46 PM)DaveH Wrote: Hello Bob and welcome to MetalworkingFun

My answer to Q1. I doubt if any noticeable difference in the home workshop.

My answer to Q2 & Q3. Again probably no noticeable difference, go with the most cost effective.

Questions 4 & 5 I will have to think about them

Hang about Bob, others may have a different opinion

DaveH

Hi
Bob
Unless you are pushing things to the limit you will not notice any differance with the smaller tool size
I use a piston type tool holder and i am very happy with it
As far as parting tools go this is what i use
http://www.ebay.co.uk/itm/GLANZE-CLAMP-T...46021476e0
I use the cheapest tips i can find
Mu previous lathe was fairly large (colchester Bantam).
My current lathe is much smaller so i modified my large tooling to fit , by milling a dove tail in them .
They go directly on to the tool post without a holder.



As far as tips go i would just use the most economical
There are loads of speed & feed charts on the net.
But for home work i would just experiment.
Dont forget carbide inserts like to be worked hard
John

John, I love the idea of dovetailing toolholders to fit a QCTP, but, one question, Is that a high speed steel dovetail cutter dovetailing your toolholder?
If yes, then let's revisit the newbie's (OP's) immediate (apparently) leaning toward carbide.
Properly ground HSS does a better job in many cases. it's part of the learning curve.

[Mayhem]

(04-05-2012, 06:44 PM)PixMan Wrote: ...Mayhem has been shopping here with me and can attest to that...

I can indeed! Bob, you cannot go wrong with Ken's advice. He certainly knows his stuff and is genuinely interested in helping others. He has helped me a lot and continues to do so.

I stumbled upon a thread he wrote on another site (which was lost), specifically upon the use of insert tooling in the home shop. I had always read that insert tooling it not suitable, as you need big machines with lots of HP and high spindle speeds. Ken disproved a lot of the myths and gave some great info. I think the main issue is learning how to read the 'code'. Once you know what all the letters and numbers mean, it becomes easier.

My advice is to post all the questions you have, read the advice and don't rush.

[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

[candiamel]

OK, so here's the next question.
I see that some lathes are mounted solidly, even on large slabs of concrete set onto a bench.
The vectrax has access holes and threads on the base to install mounting bolts or pads.
Should I install a bolt into that base and crank it down to make the machine level, or slide a thin piece of steel shim which is what seems to be all the rage for leveling machines?
Bob

[f350ca]

(04-06-2012, 08:47 PM)candiamel Wrote: OK, so here's the next question.
I see that some lathes are mounted solidly, even on large slabs of concrete set onto a bench.
The vectrax has access holes and threads on the base to install mounting bolts or pads.
Should I install a bolt into that base and crank it down to make the machine level, or slide a thin piece of steel shim which is what seems to be all the rage for leveling machines?
Bob

Not sure how heavy your 14 x 40 is. The Taiwanese one I had was around 1200 pounds, drilling and lagging it to the floor made a huge difference, reduced chatter dramatically at high speeds. I used small metal plates under the levelling screws and torqued the bed level, didn't take much effort.
My big lathe and the small Colchester I have now seem to be heavy enough that they just sit there.
Greg