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Author Topic: Drilling 3 holes on a lathe  (Read 5915 times)

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Offline mc

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Drilling 3 holes on a lathe
« on: November 28, 2011, 03:35:43 PM »
Sounds simple, doesn't it?
And I'm sure it should be, but I'm really struggling to get my head around it!

I'm working on a gang tool bar that fits in the QCTP to mount drills/reamers in via ER25 collets, and I'm now at the point where I need to drill 3 holes, 40mm apart.
I've managed to turn a few bits, including a couple threads, using the wizards, but I figured I should really learn a bit more about G-codes instead of relying on wizards.
So, after reading the manual, and trying various options, I finally tracked down the lack of movement to the G83 macro being missing from the profile folder, so I copied the standard one across from the default turn profile folder (I found the thread with the 'fixed' M83 version, but I figured I'd stick with the original one for now)

However, although I can get movement in the Manual screen by typing in G83 X0 Z-5 Q1 R1, the line doesn't even show once saved to a file and loaded in the Auto screen.
I'd like to create a file that will drill the three holes in one run, so I can edit it as I swap drill bits.

Anybody got any pointers on how to achieve this?
Re: Drilling 3 holes on a lathe
« Reply #1 on: November 28, 2011, 04:48:42 PM »
Hi,

The method I use with my gang tool setup is to call G52 offsets for the X & Z Postions of each drill tip relative to a Master Tool Tip Position.  In your case each drill will need to be offset by 40mm.  

eg G52 X40 Z0 for the 2nd Drill (assuming the first drill is the master tool and that the tip of the 2nd Drill is aligned in the Z plane with the tip of the 1st drill).  

Don't forget to cancel the G52 Offset when each successive drill has completed its task with a G52 X0 Z0 before moving to the next drill position and on completion of the 3 drilling job.  

Make sure that you withdraw each drill to a safe Z position ( I use 20mm) before calling the next drill.

As to the Drill cycles I use the peck drill macros here:

http://www.machsupport.com/forum/index.php?PHPSESSID=k39gqcfsarabqj4bmakqaon960&topic=15205.0

G83 does not work in Mach3 Turn.

Regards

Chrisjh

Offline mc

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Re: Drilling 3 holes on a lathe
« Reply #2 on: November 29, 2011, 03:42:07 PM »
Thanks for that.
Using some G52 offsets worked perfectly, although I discovered the limitations of the lathe, so I'll have to move the tool holder into the milling maching to rough bore the holes.

Offline rcaffin

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Re: Drilling 3 holes on a lathe
« Reply #3 on: November 29, 2011, 04:41:02 PM »
I'm working on a gang tool bar that fits in the QCTP to mount drills/reamers in via ER25 collets, and I'm now at the point where I need to drill 3 holes, 40mm apart.
Been there, done that, making 3 and 4 port tool head. Very useful for production - a poor man's Swiss lathe idea.

Note: doing this with the block mounted to the lathe saddle and the drill in the lathe chuck will give you the RIGHT height, so you can then use the block to hold drills. Doing it with a mill is prone to small but very annoying errors.

Quote
I've managed to turn a few bits, including a couple threads, using the wizards, but I figured I should really learn a bit more about G-codes instead of relying on wizards.
Absolutely. Sorry, but it's true imho.

There's a photo somewhere on this web site of what I made - not sure where right now, and I don't have the original any more.

Cheers

Offline mc

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Re: Drilling 3 holes on a lathe
« Reply #4 on: August 20, 2012, 06:02:51 PM »
Rather than clutter up Hoods Conect thread, here's the final item. It's taken far longer than planned to finish, as other stuff keeps getting in the way, but I've been making a point to grab the odd hour over the past few weeks to get this finished.


Gang Collet Holder by mc_mtb, on Flickr

As mentioned in my last post, the lathe simply doesn't have the power to drill steel. So after marking the holes, the holder was put into the milling machine, and the holes drilled to a mm or so under the final size, ready for boring to final size. The holder was then put back on the lathe (after using it to make a 20mm adapter for my boring head, so I could mount in in the ER32 chuck), and using a bit manually coded G-code, bored the holes out to final size -


190_LatheBoring by mc_mtb, on Flickr

This process was a bit tedious, however by the time the holes were bored to size, I had the G-code tweaked so the spindle stopped before rapiding back to the start, and I could just about have the boring head adjusted ready to hit cycle start again.

And in case you're wondering how the holder is supported, I machined a basic support that is permanently bolted to the cross slide.

Gang tool holder by mc_mtb, on Flickr

The holders were made from some 1" silver steel I had lying around. I cut sections long enough to get 2 holders out of each, faced and drilled it to 12.5mm on my other lathe (big enough for the boring bar to fit in), then mounted them in the Conect, set it to work, changed the tools when needed, then spinning the stock in the lathe, before repeating, then finally parting the two holders in the other lathe.

I'm still needing to order stub drills to try the holder properly, however using an 8mm jobber drill which just cleared the collet chuck (Z-axis travel is limited due to the ballscrew covers), it sank into some alumiunium without any issue. I'll admit I was abit worried about this after the lathes inability to drill steel, however it sank straight in without any hessitation.
Re: Drilling 3 holes on a lathe
« Reply #5 on: August 16, 2013, 03:04:06 PM »
Sorry for the thread exhumation but....mc, I'm in the process of making a QC gang tool holder for my ORAC and was wondering if you had it to do over, would you change anything?  I'm using ER16's on mine and will have the room (I think) for 4 holders but haven't decided whether to go with 3 or 4 yet.

My plan is to drill the holes close to the final size as you did but make the final cut with an endmill held in a collet in the lathe and then turn the collet chuck shanks to a close fit.

Do you find it difficult avoiding crashes with 3 tools sticking out or do things flow pretty smoothly?
Milton from Tennessee ya'll.

Offline mc

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Re: Drilling 3 holes on a lathe
« Reply #6 on: August 16, 2013, 07:33:26 PM »
There's not really anything major I would change. Instead of using a M8 coarse bolt for the rear support, I'd probably swap to a fine thread just to make adjustment that little bit easier, but it's something that once set you don't need to touch.

I've not had any crash issues, but then I'm only using 3 pretty similar length stub drills and only moving between them. It's just a case of using a bit common sense, and making sure you retract far enough away to avoid any overlap issues.
Re: Drilling 3 holes on a lathe
« Reply #7 on: August 16, 2013, 09:18:14 PM »
Thanks for the info.  I'm going to whittle mine from a solid chunk of steel including the dovetail to match the AXA tool post.  T'other end will have a sturdy bracket bolted down to the carriage plate with a 5/16-24 SHCS.  This will support the end of it in 2 directions.

Once it's set up, I should be able to quickly lock the gang tool on the QCTP, tighten the bolt at the other end and be ready to go.  That's my plan anyway.  We'll see what really happens in a couple weeks. ::)  (I'm slow.)
Milton from Tennessee ya'll.