The department where I work got a few of these machines. I have next to no experience on cnc machines. I've written and ran a couple of programs for it already but i am having a possible problem when trying to use a g84 tapping cycle.

I wrote a program that will face, turn the OD, turn threads on the OD, drill, then tap the drilled hole. (For drilling and tapping I am using a drill chuck holder that attaches to the tool post, not to sure if this is a good way to do it but they got these holders with the machine and want to see if they work).
After I got the program written I loaded it in memory and ran the graphing utility and got the program to seem to work good. When I first ran the program with no tools, just to make sure it wouldn't crash into anything it ran good up till the g84 line. When it gets to the g84 line it starts to feed but for the first second it feeds, the carriage acts funny, the whole carriage starts to shake.

Here is the part of the program for tapping:

T505 (TAP 1/2-13 UNC)
G97 S500 M03
G00 X0.0 Z.1 M08
G84 Z-1.75 R.2 F.07692

Any help would be appreciated

You say; "When it gets to the g84 line it starts to feed but for the first second it feeds, the carriage acts funny, the whole carriage starts to shake."

Does it then smooth out? I have tapped same size with a TL without any problems.

One thing I did notice with my TL1 was that the carriage would shudder a bit whenever it started moving quickly and this went away when I removed the handwheel. The handwheel runs on a rack and has clearance and would slop back and forth whenever the carriage started or stopped.

It does smooth out right away.

Out of curiosity have you ever used a drill chuck on a tool post. Does it work well, or is it better to do all drilling and tapping from the tail stock?

Thanks

It does smooth out right away.

Out of curiosity have you ever used a drill chuck on a tool post. Does it work well, or is it better to do all drilling and tapping from the tail stock?

Thanks

I do not have the tailstock and have the four position automatic tool post. Obviously I do everything from the toolpost although I don't use a drill chuck instead I made several custom holders for drills and taps. I posted some pictures in one of the threads on toolroom lathes a while back.

A drill chuck is not strong enough to hold a 1/2x13 tap. You need to use an ER-32 collet chuck mounted in the boring bar holder.

Mark Hockett

CNC machines do NOT drill and tap from the tailstock. How in the world would you get the CNC to do that??? They need to be mounted in the toolholder.
Drill chucks have no place in a CNC machine. They do not offer any where near enough grip. They are for use on a manual machine or a drill press. Drills and taps need to be mounted in a collet. I use ER32's and ER16's in my machining centers and turning centers. That works nicely. You've never had the exquisit pleasure of having a half inch drill come out of a cheezy holder and have your 3/8ths carbide boring bar rapid into the drill sticking out of your bar stock at 1428 ipm, have ya?:stickpoke

try slowing your speed to say 300 rpm,I found my tl-2 did the same and slowing the speed down corrected that.

I have to dissagree on the drill chuck theory. I use albrecht self tightening chucks in my cnc mills. On the lathes I usually use collets because of clearance and coolant delivery. I use collets in the mills too, but like the albrecht's versitilty. Meaning no fumbling for collets or taking something apart to get the collet I need. They grip plenty strong, if you have jaws that are in good shape. They even make diamond impregnated jaws so they penatrate the shanks of carbide drills. Just don't run them in reverse, like using them for a tap holder, they self-loosen in reverse :)

I have a TL-1 and I do use the tailstock for drilling. Not on all jobs, but drill a lot of copper 13/32 and 17/32 holes and it's too much for the cross slide. So I'd say it depends on the work your doing whether you choose to use the tailstock to drill.

Oh, and make sure if your using collets to hold a tap you have the collets with the square drive so the tap doesn't slip in the collet and destroy the collet. Don't ask me how I know :)

Oh, and make sure if your using collets to hold a tap you have the collets with the square drive so the tap doesn't slip in the collet and destroy the collet. Don't ask me how I know :)

This one I have yet to figure out...Yes, the tapping ER collets have the square to prevent them from slipping in the collet. But what on earth keeps the collet from slipping in the chuck? I would think if it was enough to make the tap slip in the collet, it would be enough to make the collet slip in the chuck. And there is no way to keep an ER collet from slipping since there is no square or key on it.

LOL Anyway...Just my $0.02. I use both tapping and non-tapping collets with no slippage in either.

I've had the most trouble with the 1/2-13 taps. They have such a small shank, so it's easy for them to slip and push up into the collet. I really don't think there is much of a chance of the collet slipping in the chuck. It's wedged between the two angles pretty good. Now I have the square tapping collets, so no problems. I use them for taps that stay in the machine. Otherwise I use Blitz quick change stuff.

I have had no trouble with slipping in standard er32 collets,I have used them to tap up to 20mm(3/4").Just use the right size collet do not crush one down to minimun size to fit.
If you are having trouble,seeing it is a course thread you can also try drilling a hole .2mm(.008") bigger,that depends on the fit you require.