Setting feed speed on Craftex cx700

[B-Train]

Hi everyone,
It's probably a very newbie question here :wall: but...
I just bought a Craftex cx700 lathe after some times passed on a little Taig and I want to know how I can know the resulting feed speed of a setup since it's directly link with the motor (spindle) speed ? When I put full spindle speed (2200 rpm) to cut 1" steel round bar with carbide tool, the smallest resulting feed speed seems really too fast. Am I use too fast spindle for that stock, or are my carbide tools too fast for that kind of lathe? And how can I know what is really the resulting feed speed?
Thanks,
B-Train

 

[Tin Falcon]

hmmm lookinghttp://littlemachineshop.com/Reference/CuttingSpeeds.php at this calculator 2200 rpm sounds reasonable for carbide . I would think a 1hp motor would handle carbide.
my gut said slw the speed increase the feed.

IIRC that lathe has a variable speed motor with rpm readout. . so try this.
1) support your stock ether with minimum stick out or center. make sure tool stick out is minimum. make sure took is center height.
do a little experiment set the spindle for say 500 rpm and take a cut by hand . when you get a nice chip and things feel right measure the chip thickness . repeat at 1000 rpm 1500 and 2000. pick one that works best. then set the power feed according to results. I was always taught use a slow speed and heavy feed and deep cur for roughing , high speed light feed and light cut for finishing.
in case you did not know the chip thickness you measure is same as the inches per revolution setting on the lathe.do not know how many selections so close will likely have to work.


y ou can always try high speed steel but slow down the speed to like 350 rpm.

what steel this can make a huge difference. Mystery metal is not the machinists friend. I have had some steel that cuts great another section of the same piece and it will not cut due to hardness.

I noticed 2200 rpm is max speed so save this for your light finished cuts.

tin

 

[mygrizzly1022]

Hello B train
If you are relatively new to machining I think you'll find the carbide is not your friend. High quality carbide is the choice in the production environment, not so much in the hobby shop. Production carbide tools are very expensive and are best suited to heavy ridged industrial machines The bulk of most newcomers to the metal lathe would be better served with high speed steel.
Do an Internet search for tool bit grinding. It is not all that hard, and it's a skill you will benefit greatly from mastering. A Utube search for "mrpete 222" will yield a wealth of information, for some one new to machine tools. His videos on tool bit grinding are quite well done. Teach yourself to grind high speed steel and you'll never regret it. Grinding specialty tools and cutters is all part of the skill set you are going to need to master.

Regards Bert

 

[B-Train]

Hi!
I agree with you Grizzly. These tools were not a good choice... I'll try with some hss tools with slower spindle speed. After that I'll see about the feed rate. I took was I think the easy way . I already know Mr. Tubalcain and saw many of his videos. He does a so great job in teaching and explaining and most of all sharing all this knowledge!

But about my question, the minimum feed resulting from a 2200 rpm spindle still seem very fast and I don't know where I can find the real value of this feed anywhere...
I use Gwisard calculator for my basic setup. It worked well for most of my other works on my Taig lathe and cnc mill (even with some carbide tool...). But the feed mechanism on a Taig is not a "direct screw" system and let you "feel" the need. I tried some setup resulting from that same software on the Craftex but still search were I can find the real value of the feed vs spindle...

But the first thing I will do is change my tools type to get everything works well, I'll try tight setup later...

 

[Tin Falcon]

But about my question, the minimum feed resulting from a 2200 rpm spindle still seem very fast and I don't know where I can find the real value of this feed anywhere..

slow down the speed take a cut and measure the chip thickness. this will tell you what the feed rate is. check the setup of the change gears. from what I know about the 10 x 22 lathes is you need to have the change gears set up for the knobs to work properly. if you are using a screw feed that would be too aggressive.
tin

 

[mygrizzly1022]

B-train
When you think about it, a lathe cutting tool is a lot like a drill bit. When drilling good material with a nice sharp bit in a drill press you have probably hit that sweet spot, where you are forming nice uniform chips that spiral away from the bit in a satisfying bluish curl. It didn’t start out that way; you got there over time experimenting with spindle speeds and down pressure.

Unlike the drill bit with two cutting edges the lathe tool has only one, but the goal and the principals are the same. You need to get to know your machine, use the hand feed for a while so you can feel what the machine is telling you; learn about its sweet spots there will be many.

You didn’t learn how to get the most out of you Taig overnight, this one will be no different. Your Taig didn’t have a power lead screw so you are used to it. So do some hand feeding and save the power feed for later
Tins advice about measuring the chips is bang on. Take your time and enjoy the process it’s a hobby right.

I will be following your progress with your new toy as I will soon be relocating and downsizing and I have a cx700 on my wish list. I will be looking forward to you impressions after you have had it for a while.


Have fun….. Bert

 

[B-Train]

Thanks a lot guys, I'll keep you inform with my progress .