Doosan LSY2500 tapping with subspindle

[DocHod]

HI anyone with experience using a Doosan LSY2500 as to how big of a tap are you able to use when tapping in the subspindle the LSY2500 we have , if the tap isn't sharp forget it we were tapping 1-5 acme with approx. 55% thread depth in soft brass and if the tap we were using was anywhere close to being dull man what a pain with alarms. the alarm that comes to mind has to do with a hydraulic pressure drop or something on that order any positive comments would be helpful , it may not a machine issue but a tooling issue but it's got me thinking if I can tap the same part with the same tap that came out of the LSY2500 on an old piece of cr$p machine with no problem whats going on ? and I know the tool is dead center with the spindle when it goes into the tapping cycle on the LSY2500 I checked it , thanks again.

[dcoupar]

What RPM were you running?

[DocHod]

dcoupar I tried it at 75 rpm's to 150 rpm's

[mroy0404]

try single point turning of the threads

[dcoupar]

I'm out of the office (and out of my element), but I'd suggest you look at your manual and find what horsepower and torque you have available at those RPM's... my guess is not enough to tap these holes. If you can run more RPM's, you might be able to do it, but at these speeds, I believe single point threading is more practical for this size acme thread (as mroy0404 suggested above).

[DocHod]

With the size of the bar to accommodate the size of the insert for 1"-5acme that we have is the problem , anyone know were I could find this type of tooling to single point thread that would meet the specs for 3/4-6 to 1"-5 acme that would be great , thanks.

[STS_John]

We run 3 Daewoo's, SY's and LSY's. The sub spindle does not have much horsepower, good for most second operations, but still not near what the main spindle has. We always try to program the part to do all heavy load operations in the main spindle. This has taken some "out of the box" thinking sometime. We have cut some heavy load thread applications on the sub spindle, we did this by milling the threads. I don't know how deep your acme thread is, but you might look at milling the thread. thread milling on the Daewoo sub spindle's is easy and fast. Your 1" thread is big enough to get a good size thread mill into the bore. Once we have made a X move to position the thread mill radially, we use Z and C commands to generate the thread, when the thread is on centerline of the part. We use helical commands and live tooling to mill threads that are not on center line.

I know this won't work on your Acme application, but another thing we have found on sub spindle thread applications is to use roll form taps. We are increasing spindle speeds and getting into better torque curves. We have been tapping with roll form up to 1" diameters, with 3 to 4 times spindle speeds, and 10 to 20 times tap life. Depends on the material, but we have been doing as small as 8-32TPI to 1"-14TPI in annealed 4340, 300 stainless, 6061 aluminum, and S5 tool steel with great results.

Let me know how deep your Acme thread is, I have some good recommendations on thread milling tools (we do a lot of thread milling on our VMC's and LSY-SY lathes) I can send you a reference program for milling threads in the sub spindle. Drop me a PM and give me some info on the thread, is it on centerline of the part, how deep is it?

Good Luck
John