Spade Drill Does Work in Aluminum; Big Hole Boring on Drill Press.

[Geof]

A few threads have had the query "will a spade drill work for drilling large holes in aluminum?". The answer is yes at least for a 1" spade bit going through 1/2" 6061-T6. The hole is shown in picture 1. The spade bit was completely standard not specially sharpened, a 1/4" pilot hole was drilled and then the spade bit run through dry at about 400 rpm taking around 3 minutes to finish the hole. In the process creating much vibration and noise. The bit wandered away from the intended location and the finished size was about 1-1/16" but this was not important because the goal was a 1.375" hole bored with only hand tools, a cheap drill press and a cheap grinder.

Picture 2 shows the start of a "line boring" setup on the drill press: A block of wood bolted to the table and drilled to take a 0.750" O.D. 0.500" I.D. 3/4" long brass bushing. (Bit of cheating here; this was turned on a lathe but identical bushings can be bought at a low cost.) The hole for the bushing was 3/4" deep with a 9/16" hole passing right through the wood and through the hole in the center of the drill table.

Picture 3 shows the complete line boring setup: a 1/2" diameter shank held in the chuck with a notch filed in the side at a 45 degree angle and a toolbit held in the notch with two 10-32 skt hd bolts passing through the shank and it into a small metal strap straddling the toolbit. This picture actually shows the finished hole which was reached in four cuts. The toolbit is adjusted by loosening the clamping screws and tapping it forward very gently, taking a small cut and checking the size.

Picture 5 shows the finished hole after deburring. The final size was just under 1.376" well within the range for using Loctite to secure a bearing.

[JavaDog]

Heh, that's pretty cool. When I was told to try it (in one of my threads) I really wasn't sure it would work. Cool to see that it does...

Just out of curiosity, why did you run it so slow (400rpm)? Have you tried the same with some cutting fluid?

[rcazwillis]

You say the bit wandered. Could the 1/4" pilot hole be the culprit. Maybe a much smaller pilot hole would avoid the wondering.

[Geof]

Javadog;

Two reasons to go slow: The motor did not have enough oomph at a higher speed and the vibration was much worse. To control the vibration and bouncing with the spade drill it was necessary to drive it in hard just about on the point of stalling.

rcazwillis:

Yes a smaller pilot might do that but everything bounced around so violently that I do not think it would be a good idea to trust getting the hole in the correct place.

[dapoling]

A safer way to have accomplished this task if you insist on using a drill press which we all know is not rigid is to use a hole saw.

The setup you have is not rigid and dangerous, it should come with a warning.

Your information says you are a owner of manufacturing company for those with disabilities why are you using something like this?
Are you an owner of a company of 1 ?

[RICHARD ZASTROW]

Geof, Years ago I operated an Asquith radial drill. The nameplate said "drilling and boring machine". The "T" slotted table had a bushed hole that matched up to a set of piloted boring tools similar to your set-up. Worked beatifully! To locate the tool over the bushing, I would let the arm "float" while rotating slowly (not cutting). When it centered itself I pushed the "lock" button, securing the arm in place. Set speed and feed and proceeded to bore holes. This machine was designed to function this way and did so without wobble or vibration. Good old iron.

Dick Z

[Geof]

Originally Posted by dapoling A safer way to have accomplished this task if you insist on using a drill press which we all know is not rigid is to use a hole saw. The setup you have is not rigid and dangerous, it should come with a warning. Your information says you are a owner of manufacturing company for those with disabilities why are you using something like this? Are you an owner of a company of 1 ?

What hole saw can cut to an accuracy of plus minus a thou or so? For goodness sake I say this is a demonstration.

Regarding my company you can go find my posts and threads and you will find a bragging description of all my machines I put up a while back. No it is long past being a company of 1; something like 25 years past that. It is not large but does have a total of about 16 employees and a whole bunch of Haas machines.

Why are you still insisting on being antagonistic? I thought I offered an Olive branch; what do you want me to do catch a Dove to carry it?

[dapoling]

Originally Posted by Geof What hole saw can cut to an accuracy of plus minus a thou or so? For goodness sake I say this is a demonstration. Regarding my company you can go find my posts and threads and you will find a bragging description of all my machines I put up a while back. No it is long past being a company of 1; something like 25 years past that. It is not large but does have a total of about 16 employees and a whole bunch of Haas machines. Why are you still insisting on being antagonistic? I thought I offered an Olive branch; what do you want me to do catch a Dove to carry it?

Geof then you have all these machines and yet you go to a drill press with a wood spade drill that you say you can hold a tolerance of +/-.001 what a crock!
You keep making statements with a tool and setup that is so weak and dangerous, then I will call you on them.

There is no reason for an olive branch as I have no ill feelings with you or anyone in the forum, it is if I find something that's dangerous, inaccurate, false statements or if I have something to add I will state my view point as with any other member in here.

You see this as being antagonistic I see it as setting the information straight.

the rest I will send in a PM to you as it does not belong in a thread.

[AMCjeepCJ]

Originally Posted by dapoling ..........why are you using something like this?

He's NOT using something like this, it was an experiment for crying out loud!! Haven't you ever experimented just out curiosity?? Maybe being a shop owner all my life and only once an employee causes me to have a completely different mentality but I goof off trying stuff ALL the time even if it's dangerous... (Don't anyone dare take that statement out of context, lol...)

Now I should explain that anytime I do anything I am almost paranoid about my safety... The left side of my body was 100% paralyzed for quite awhile through no fault of my own and I have no desire to EVER get hurt again... However, I don't let fear cloud my judgment, I think things through, start small and work my way up through systematic testing if the new idea requires such an approach...

I see no reason not to try something like this thread describes IF IF IF you are a true professional machinist and you are willing to accept responsibility if something goes awry!! If no one ever took a risk, where would we be?? If you're Caucasian, I'm guessing you'd be in Europe still and probably no where else... If the explorers we learned about in elementary school were born today and became machinists, I bet they'd be trying all kinds of 'insane' things just out of pure curiosity...

I'm going to guess you're not a big risk taker in general and probably wouldn't like not having a steady weekly, bi weekly, monthly, etc. income... My opinion here is that there is absolutely NOTHING wrong with that mentality at all... We're ALL wired different... However, assuming that average people are reading these posts and apply an average amount of common sense, I see no problem posting the results...

Here's an idea, did you ever think that since Geof took the time to post the results and the inherent problems associated with doing it this way that MAYBE someone who was contemplating trying it themselves will now shy away from it because even though it was proven to be possible, it's neither easy nor super efficient to do??

I'd much rather someone else test a new shark suit and let me know it doesn't work than to have to discover EVERYTHING on my own...

[AMCjeepCJ]

Originally Posted by dapoling Geof then you have all these machines and yet you go to a drill press with a wood spade drill that you say you can hold a tolerance of +/-.001 what a crock! You keep making statements with a tool and setup that is so weak and dangerous, then I will call you on them.

Unbelievable, did you miss the ENTIRE PART about the bushing and did you NOT see the setup he built to bring it the finish dimension?? I'll would be willing to bet you, that with his arrangement and a lap or hone of some sort for the final fitment you could easily get the diameter to within' .0002" if you had any patience and skill at all... With my experience on manual equipment, I find all of his info entirely reproduceable with almost no effort...

Granted I wouldn't bother doing it this way, it's not efficient for me to create a hole like that and as Geof stated, the X Y location of the hole was not extremely precise with this method... His only concern was to see if it was even possible to hold a tight tolerance with a cheap flimsy tool and a drill press...

Let me ask you this... Just because you can't long jump over 26 feet, does this mean no one can?? Your EXPERIENCE in life doesn't account for all the experiences of others... However, you could argue that since you cannot do it, then it therefore cannot be done... Argue as you might this analogy very closely resembles the closed minded thinking you expressed above...

Please keep in mind he DID NOT finish with the spade drill, you're right, you couldn't do it with that setup but Geof NEVER said he held that tolerance with that flimsy drill, he only used it to punch a hole in the aluminum for the other tool he used in conjunction with the bushing~

GO LOOK AT THE PICTURES HE SUPPLIED!!

[dapoling]

Did you see the post where he talked about the vibration?

In the process creating much vibration and noise. The bit wandered away from the intended location and the finished size was about 1-1/16" but this was not important because the goal was a 1.375" hole bored

Even with a bushing to try an keep this tool in line it still failed to do so do to the rigidity of a drill press trying to counter act the cutting forces.

It drilled 1/16 over sized for crying out loud sure you can dismiss this as you still have take it out to 1.375. You do not see this being a problem, it is telling you your setup is poor you just are accepting unsafe conditions which is foolish.

Your accepting conditions as this speaks volumes about your concern for life and limb or lack there of, these machine can and will kill someone by ignoring safety precautions or accepting unsafe conditions and then try and play it off as you are on the edge of finding something that has never been done, lol with a spade drill for wood in metal, it stinks of dangerous no matter aerosol you want to use to make it smell better.

now when it comes to having a bore being honed to .0002 yes very possible, would you like to tell others on how to do this? what precautions to take so this can happen and how much material would you leave in the hole so the hone can do this job with in that tolerance, how much our of roundness would be acceptable so hone can hold this tolerance?
Hint you will not do it with a spade drill or on a drill press! Do you know why?

How far do you want to dig that hole you're digging for yourself?

I even posted a viable option but I guess that is to easy.

[Mitsui Seiki]

Even with a bushing to try an keep this tool in line it still failed to do so do to the rigidity of a drill press trying to counter act the cutting forces.

I think the bushing was used with the boring tool.