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Drilling with the cross slide

If you have attached your QCTP as Robin or Stefan have done (it can't rotate) then drilling, tapping and die threading using the carriage is superior in my opinion. I no longer have to wind the carriage out of the way from the tail stock, I can easiliy sap between drill chuck and tap/die holders. And then there is peck drilling, either with an ELS (in my case) or by hand. Lastly, for large holes it is simple to switch to boring tools after drilling a start hole.
With my DRO I dial in the tool holder once, and then select it (SDM #3 :-) and align it to 0.
Bonus is DRO works on the Z axis. Another bonus, you can thread mill using the carriage.

My lathe is a 1022 and I don't have MT drills.
 
gerritv said:
you can thread mill using the carriage.
Click to expand...
What??? Thread mill - true thread milling on a lathe? Please tell us more Gerrit.

I've done some thread milling on my cnc mill. I bought some expensive tooling to do that and I'm terrified to actually use them. I was handed down a few carbide thread mills and managed a couple of holes and also broke one of the tools quickly. I'm pretty gun-shy now. When I try this again I'm going to trial it first in wood, then in aluminum, then in steel to try to reduce the risk of breaking it instantly.
 
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Here is a single point one, $73USD plus shipping. The single point ones are quite slow.

1750201362521.png

Here is a multi point one, call it $300CAD plus shipping.

For those unfamiliar with this threading approach. Your CNC device spins the thread mill and cuts the thread by simultaneously going around the perimeter of the hole and traversing the length of the hole thereby milling out the thread. A multi point thread mill can carve threads really fast. You probably need to cut the thread 3 times. The tool is smaller than the hole diameter. A really minor mistake in feeds/speeds depth of cut and the tool just busts.

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here is a pretty good diagram from: https://www.researchgate.net/figure...cal-milling-bottom-top-helical_fig1_345220482
 
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Stefan is always the source of interesting solutions.
The only place to buy thread mills for hobby use is AliExpress. Quality stuff at affordable prices.
Works with an ELS also of course
 
Janger said:
What??? Thread mill - true thread milling on a lathe? Please tell us more Gerrit.

I've done some thread milling on my cnc mill. I bought some expensive tooling to do that and I'm terrified to actually use them. I was handed down a few carbide thread mills and managed a couple of holes and also broke one of the tools quickly. I'm pretty gun-shy now. When I try this again I'm going to trial it first in wood, then in aluminum, then in steel to try to reduce the risk of breaking it instantly.
Click to expand...
NYCNC.com has a very useful spreadsheet and other informatoin on parameters for thread milling. Still, it is butt-clenching to watch a M2 threadmill plunge into the bottom of the hole and then start thread cutting. You hope all is well at the end. I did do a hole pattern on my cnc mill bed plate, M6. which worked out extremely well.
nyccnc.com

How to Threadmill! - NYC CNC

Post Views: 73,393
nyccnc.com nyccnc.com
 
gerritv said:

Stefan is always the source of interesting solutions.
The only place to buy thread mills for hobby use is AliExpress. Quality stuff at affordable prices.
Works with an ELS also of course
Click to expand...
I havent' even got to the thread mill part. Instead there is a great demo on prepping and black oxide treatment of a part. !
 
This video is worth watching.

Watching Stefan cut the thread with the single point tool at about 20 minutes it appears to me he: engages the lead screw and does not disengage the lead screw for the rest of the operations. Instead he does a cutting pass, stops the lathe, out feeds the thread mill, reverses the spindle to wind the carriage back, stops the spindle, then feeds the thread mill back in to cutting depth, and restarts the spindle forward for the finishing pass. No thread dial.
 
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Janger said:
This video is worth watching.

Watching Stefan cut the thread with the single point tool at about 20 minutes it appears to me he: engages the lead screw and does not disengage the lead screw for the rest of the operations. Instead he does a cutting pass, stops the lathe, out feeds the thread mill, reverses the spindle to wind the carriage back, stops the spindle, then feeds the thread mill back in to cutting depth, and restarts the spindle forward for the finishing pass. No thread dial.
Click to expand...
yes, because that is how you thread on a metric lathe. Leadscrew stays engaged. With an ELS the same of course. The main point is that you do the threading in 1 or 2 passes instead of a bunch. Workpiece deflecton is also minimized.
 
gerritv said:
Leadscrew stays engaged.
Click to expand...

That is how I used to do metric threads.

Today, I disengage the leadscrew and then I use the thread dial to engage the leadscrew at the same location. It's much easier for this old man to do that than it is leave the half nut engaged. Here is a full description of the method:

Susquatch

Thread 'Metric Threading on an Imperial Lathe'

I was wondering how a metric threading dial works and ran across a really cool tip on cutting metric threads with an imperial lathe.

I've always thought you had to leave the half nut engaged while you start, cut thread, stop, retract cross slide, reverse, stop, return cross slide, advance threading tool on compound, start, and repeat. But this method significantly increases the risk of a crash when threading to a shoulder.

Turns out that it isn't necessary after all.

The trick is to cut the thread as usual, disengage the half nut as usual, then stop the lathe, then reverse the lathe...
  • Like
 
Before I had CNC capability I usually used the Stefan leave it engaged method. Now with CNC, the process is automated so just watch and squirt a little cutting fluid as required.
 
Is my lead screw engagement crap? I have about a 80%-90% chance of the handle going down at the right moment with the thread dial wheel and perhaps 10% chance of it being too early/late. I have a modern C0603 14x40 lathe. When it does not work pressing down on the handle the engagement is a bit "rough" and seems to get a bit stuck or something... I was thinking I just didn't have enough skill yet but maybe there is also a bit of a problem? @kevin.decelles you have a new version of that lathe what is your experience?
 
Janger said:
Is my lead screw engagement crap? I have about a 80%-90% chance of the handle going down at the right moment with the thread dial wheel and perhaps 10% chance of it being too early/late.
Click to expand...

I suppose that is possible.

But I also think there is a bit of a knack to doing this. I have found that my half nut will do the same thing if I don't do my part. Basically, the half nut has some elasticity to its engagement and that allows it to engage on a tooth of the lead screw instead of in the groove where it belongs.

I have perfected the process on my own lathe (YMMV) as follows: as the thread dial comes around to where I want to engage it, I apply VERY light pressure to the handle. As soon as the teeth on the half nut pass the teeth on the lead screw, the teeth on the half nut will fall into the grooves of the lead screw and I can latch it into place the rest of the way.

The trick is to develop just the right pressure and focus on feeling when the pressure goes away. I can do it without even looking at the thread dial. That might work for you too. It also helps if the lead screw is well oiled.

I think many of us don't oil the lead screw as often as we should. When I am threading, I am careful to liberally pre-oil the leadscrew in the range of the half nut travel before I even start actually threading.
 
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