Setup question: drilling big holes in small discs.

MwTech Inc · May 5, 2021

Ok, this is not a trick question. I've been drilling holes for 30 years but..................

New toy in shop, Cincy 4x13 radial.........

Have 80 plus 4.00 dia ,500 thick carbon discs to put a 1.375 hole in the middle, also some 1.00 thick will get holes also.

Did this job a year ago but not using the radial, my hope is to pour the coals to it and pop these holes out quicker, have big ol morse taper drills.

My concern is the bit will bite and spin the disc in the vises that I have...........maybe not, but drilling the first batch it required a lot of pressure to push bits thru on the turret lathe,(using 3 jaw chuck to hold) although I did do three passes using Silver & D drills which took forever. I'm after one pass and spin out big spirals.

So there must be some trick....right?????

Course would be really neat to stack them buggers......................

Limy Sami · May 5, 2021

i know you want to use your radial, but what turret lathe did you use?

MwTech Inc · May 5, 2021

my ol faithful W&S #3

She did OK, but even with sharp bits that last bit I had to assist the feed pretty hard, i didnt want to wipe out my feed clutch.

And still even using good 18n chucks the bits would still spin at times.
Just the whole process to slow

Milland · May 5, 2021

If'n it was me, I'd thin the point (not split, thin) of a to-size drill, and clamp a three or six-jaw lathe chuck on the radial for holding. Keep the drill sharp/thinned, one-shot the hole. Do a good job with the thinning, otherwise you'll cut oversize and tapered.

If you get too much deformation with hard jaws, use steel soft jaws bored to suit.

kb0thn · May 5, 2021

Old lathe chuck on the table of the radial drill? Jaws flipped around on it so clamping the OD and no way for it to move down?

I'd do it with an insert drill on the CNC lathe in about 15 seconds per hold. Or less than a minute if I didn't have the drill and had to bore to final size. My neighbor would just do it on his iron worker. At least for the 0.5" thick disc. Keeer pop!

MwTech Inc · May 5, 2021

Dang .......

Slap me in the head...............never even crossed my mind to use a chuck......Duh on my part. :willy_nilly:

And I have an old chuck here.........

Well problem solved.....

Ok . no expert on sharpening drill over 1" or so as I use my Darex..

Any way to see a picture of a bit sharpened as you suggested as i will need to hand sharpen.

Milland · May 5, 2021

Hope this will help, or try your own video search for web thinning drill bits:

How to Sharpen a Broken drill bit and thinning the web - YouTube

Milland · May 5, 2021

kb0thn said:
My neighbor would just do it on his iron worker. At least for the 0.5" thick disc. Keeer pop!

Unless there's a pretty good hold-down at the punch, wouldn't you likely get a large Belleville washer doing this?

Limy Sami · May 5, 2021

My Clarkson Osbourne drill bok shows <>275 rpm for 100ft / minute @1.375 dia, ............witha feed rate of 0.019 - 0.024'' / rev
So say 0.020'' / rev feed = 5.5'' / min

Any chance of being able to tack weld the discs together?

Oh and get rid of those S&D drills and use a proper MT

Milland · May 5, 2021

Limy Sami said:
My Clarkson Osbourne drill bok shows <>275 rpm for 100ft / minute @1.375 dia, ............witha feed rate of 0.019 - 0.024'' / rev
So say 0.020'' / rev feed = 5.5'' / min

Heh, I was thinking .010/flute while reading the OP.

Any chance of being able to tack weld the discs together?

I don't think I'd do this due to the possible spreading effect of the "cap" at the bottom of the upper piece. I'd do them singly.

Oh and get rid of those S&D drills and use a proper MT

Pretty sure the OP would be doing that with his radial.

I keep having fantasies of buying a radial drill, then remind myself of the weight and size and my (now) limited space. I guess I could put it where the car lift is...

Limy Sami · May 5, 2021

0.010'' / rev? .that's for 1/2'' drills, ...I thought the OP wanted to drill holes and not ponce about like a princess with a navvy's prick

Milland · May 5, 2021

Limy Sami said:
0.010'' / rev? .that's for 1/2'' drills, ...I thought the OP wanted to drill holes and not ponce about like a princess with a navvy's prick

Hey you citrus sailor, I said .010 flute, not rev. I was agreeing with you...

[I guess the NHS has cut back on eye exams?

]

MwTech Inc · May 5, 2021

Limy

Yea i know S&D drills..but hey we all have to do some stuff like that sometimes.......

Cant weld discs

Od is not super critical but will not be machined any further from provided stock, but the OD does need to stay nice, jaw marks would be acceptable tho......

Milland
Thks for link

lars66 · May 5, 2021

Annular cutter with coolant inducer and 3 jaw chuck mounted on a plate to bolt on the drill table.

Limy Sami · May 5, 2021

Milland said:
Hey you citrus sailor, I said .010 flute, not rev. I was agreeing with you...

[I guess the NHS has cut back on eye exams? ]

My oops

Limy Sami · May 5, 2021

lars66 said:
Annular cutter with coolant inducer and 3 jaw chuck mounted on a plate to bolt on the drill table.

That's the route I would take, IMO twist drills aren't the most effective power and workholding wise, and if you don't need the depth go for the annular, ........which is probably cheaper than the twist drill.

MwTech Inc · May 5, 2021

Let me back up.....My sharpener is a M5 by Darex not one of those doctor things... :willy_nilly:

so i used to good points, and we split a lot.....

Found a company called Oliver of Adrian that makes a drill thinning machine...they have video showing operation and results.

DDoug · May 5, 2021

Fix the feed clutch on the W&S, get rid of the jacobs chuck for the drills, and set a depth stop.
so you can let it eat while you de-burr the last one.
Try an insert drill, you'll need to hook up a coolant hose to it, but it would be "once and done, no pecking".

cyanidekid · May 5, 2021

Jesus, twist drills just plain suck for thin ratio holes, annular cutters, or for really thin stuff, step drills. I wouldn't event try that with twist drills. 1 3/8 in a 1/2", oh yea, annular cutter.

Nmbmxer · May 5, 2021

It’s going to suck using that large a twist drill in a plate that thin, isn’t the taper on the drill longer than the part is thick?

Use an annular cutter, much less steel turned into chips.

Setup question: drilling big holes in small discs.

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