Deep drilling aluminum

Standard drill cycle G82. I don't use it much, but it is faster. When you get more than say 4D deep, the chips often quit feeding. The result is a broken drill JAMMED in the hole. Happens most often on nearly finished parts. DAMHIKT

I don't try for top speed on one of parts. Start machine and do something else. I like to see how many machines I can run at once - four is the norm.

Or I use run time to surf RCM or even clean up the shop.

' drill cycle with dwell ' format is G82 X_ Y_ Z_ R_ F_ D_ Q_ ' X is coordinate ' Y is coordinate ' Z is bottom of hole Z value ' F is feed ' R is start point at top of hole, can be ommitted, then start point is current Z readout ' D is dwell time ' Q is dwell peck distance, if 0 only dwell at bottom of hole

No dwell is required to break the chips. The chips will break the instant you stop cutting, i.e. when you reverse the feed to retract. The bit is still spinning and no new metal is being cut to grow the chips, so they break off from where the cut ended. Any dwell only add time for the chips to rub more, generate more friction heat, gall the inside of the hole and potentially jam. The whole idea of a peck drill cycle is to get down to where you are cutting fast, make a short cut and get the heck out of the hole fast to evacuate the chips.

Yes, I used peck drilling cycle and it did retract at max speed (it is actually fun to watch). It also plunged back down at max speed also.

i

So G83 is still safer? Right?

I now browse the web, etc from the CNC mill. I configured the kernel to dedicate one CPU to realtime tasks only, so no matter what I do on the other CPU, does not affect the realtime task.

i

Pete, I thought that a dwell would not be accompanied by withdrawing of the drill. Just dwell, break chips and keep drilling.

Anyway, it is really fun to watch the mill use a peck and drill cycle. I will try to up the speed.

I crashed yesterday and went to bed early as I was very tired. Had no time to try anything. I will take pictures of my manual Bridgeport tonight.

i

I meant to say "up the feed rate"

i

If you use that method, you need to do it one of two ways - either with very short feeds between momentary dwells so you produce small chips that will feed up the drill flutes without jamming, or very long aggressive feeds to make continuous chips all the way up the flutes, break them and then do the same again to force those chips up and out. Anything in between is likely to jam badly.

You can go quite aggressive in most aluminum (except a few gummy alloys), aluminum is generally very nice to machine.

I know the feeling, I've had a bunch of different projects going on here lately. After finishing that island table, I went right to working on a

1954 Ford NAA tractor overhaul, which I am hoping to complete and get out of the way before coming back with the new mill. In parallel with those projects I have also been working on a remodeling project at a friends store, and of course also my "real" job.

...

Does that NAA have a live PTO? My '53 Golden Jubilee NAA does not. I had heard this was the last year without the live PTO.

Karl

Say, I'll mention the Achilles' heel on that machine. its the Sherman set up/step down tranny. There is no way to add oil to this tranny located under the steering column. It runs dry and the front bearing and main tranny shaft burn out. No more parts available from Ford. Long wait at any salvage yard for a replacement tranny priced at $500 (eight years ago)

Luckily, I knew a machinist with three days to spare after mine burned up and locked the tractor wheels solid.

If you have yours apart give this unit some long overdue attention.

Karl

No Sherman over/under on this unit. I'm not positive on the live PTO, the Jubilee / NAA has live hydraulics, and there was some aftermarket kit for live PTO. It's reported that this unit may have that modification, but I'm not far enough in to be sure. I got it running the other day, next on the agenda is to go through the hydraulics and see what may need to be done there.

One thought on that Sherman trans issue - Since the Jubilee / NAA has live hydraulics, perhaps you can plumb a line to supply lube to the add on trans and of course a larger drain line back to the sump. I'd use the UTF fluid for this of course vs. straight hydraulic fluid.

Let me know if you have ny questions. I know these old Ford tractors well enough to lay all the right wrenches out in the order I'll need them on any repair.

That's a real good thought.

Karl

This is a tractor that a friend of mine just got cheap, not running though had run a year or so earlier, reported may have hydraulic issue, needs one new rear tire. For $1,200 probably not bad.

So far we have changed the oil and oil filter (has screw on adapter) and put in good M1 5W-30. We cleaned and rebuilt the carb, replaced radiator hoses and drained old coolant (refilled with water for now). We cleaned up the wiring a bit, still have to complete the Delco alternator connections. Also cleaned up fuel lines, etc.

It now starts and runs well, I set the idle to 450 RPM (optical tachometer), and it runs up to higher RPM smoothly. I'm getting ready to reinstall the hydraulic pump (piston style, removed while working on the engine), drain and fill all three sumps with UTF and see what's up with the hydraulics.

I have Kroil soaking on the brake drum screws and we'll see about pulling and inspecting those eventually, though they do seem to be working ok. Some bent lift links will spend some time in my press for some straightening. Overall the tractor seems to be in fairly decent shape.

If you get those screws out without drilling, let me know. I've had to use the left hand drill bit on the last six tractors.

The next weak point on this tractor is the rear axles. jack the rear up and try to wobble the wheels side to side, most likely you'll have a lot of play. There's a taper spline to replace. if not too bad, just the spline on the hub, otherwise, the axle too (painful $)

If you want, a company called genesee products makes an electronic points replacement that fits right in the distributor. I've left my tractor sit over a month and tried it at -30. Starts in a second. of course, that includes a change over to 12 volt GM alternator system too.

Karl

One on each side came out without even using Kroil. The other two didn't want to unscrew by hand so I shot them with Kroil and let them sit a few days. I'll probably try them with my impact driver to let the shock help break any remaining rust.

They seem ok, but the wheels are off it at the moment.

Already have the Delco alternator and 12V batt on this one. I saw the Genesee ignition modules, but so far the current ignition components are ok. If they act up at some point I'll recommend going electronic. I've got a nice little Kubota B7100DT, so I don't need no steenkin' ignition on mine :)

What's that Lassie? You say that Ignoramus4117 fell down the old rec.crafts.metalworking mine and will die if we don't mount a rescue by Wed, 01 Sep 2010 22:50:27 -0500:

If you look at the parameters in your controller, you should find one relating to G83. You should be able to have it do just as you describe. On the controllers that i use, the parameter is called "G83 high speed".

========== I just hacked another cnc utility. This one generates the G-code to "pulse drill" to produce very small/fine chips that will feed up the flutes when deep hole drilling. I placed this in the public domain. see

only the most basic G-codes so should run on most controllers. Down side it is all inline code so the file is long.

User will need to provide the start and end block code and locate the drill over the spot where they want the hole. It is text based but should run on most any version of windows

-- no dos box required. User must input a number of items on screen.

Ig -- check your email - I sent you a copy of the zip file as an attachment.

Enjoy -- any suggestions/feedback appreciated.

-- Unka George (George McDuffee) .............................. The past is a foreign country; they do things differently there. L. P. Hartley (1895-1972), British author. The Go-Between, Prologue (1953).

[ ... ]

It *should* do that -- and switch to normal feed speed about

0.020" clear of the last cut bottom or so.

Enjoy, DoN.

George, I unzipped your zip file, it is pretty clever , very nice.

I will try to do the same as a G code subroutine.

i