Can I use a right hand drill for a left hand tap?

Techguy · Apr 1, 2014

I have parts that require a left hand tap but all I have are right hand drills. I do have a left hand centerdrill to use if that will help offset the drill rotation. The tap is a 3/8-32, will I have trouble with such a fine thread tap in aluminum. The machine is a really old chinese benchtop mill I put small stepper motors on and I have a stepper motor for a spindle so I can reverse the spindle. My software is driven by a spreadsheet so programming is easy.

Do you think I can tap at 2500 RPM? The stepper motor says it can go that fast. It says 2.5 amps on the motor so that is 2500 RPM right?

Any help would be appreciated as I have 4000 holes to tap.

I asked Schneider Machine but he wasn't really any help.

Thanks,
Dan

athack · Apr 1, 2014

Righthand drill is fine if you use it in a lefhand spindle.

4/1/14

Joec@westminster · Apr 1, 2014

Huh? oh yea, its April fools!

robosilo · Apr 1, 2014

*slow clap*

Davis In SC · Apr 1, 2014

Unless I am missing something/misinterpreting the question..... A hole is a hole, as long as it straight, with a decent finish, Be it drilled, wired, bored, or what ever.. RH drill is fine..

allloutmx · Apr 1, 2014

only use a left hand drill if you need to push the part down

Safarir · Apr 1, 2014

Techguy said:
I have parts that require a left hand tap but all I have are right hand drills. I do have a left hand centerdrill to use if that will help offset the drill rotation. The tap is a 3/8-32, will I have trouble with such a fine thread tap in aluminum. The machine is a really old chinese benchtop mill I put small stepper motors on and I have a stepper motor for a spindle so I can reverse the spindle. My software is driven by a spreadsheet so programming is easy.

Do you think I can tap at 2500 RPM? The stepper motor says it can go that fast. It says 2.5 amps on the motor so that is 2500 RPM right?

Any help would be appreciated as I have 4000 holes to tap.

I asked Schneider Machine but he wasn't really any help.

Thanks,
Dan

You can use a right hand drill bit but you need to flip you mill upside down. 2.5amps is the theorical limit rpm of your motor, just plug you servo directly in your wall power outlet. If you are in the us, that is 115v so 115000 rpm. You should be able to do all your holes in less than a minute. At this speed, you can use tapping oil but peanut butter is much better

lanb · Apr 1, 2014

To do this you need to run one false tapping cycle before the first real hole drill, that way the spindle is rotating in the correct direction for drilling. You drill the first hole then swap out the drill for the tap revers the direction, tap swap out again then drill. Kinda like they do on screw machines to shorten production cycles (OK for the experts I know this is not exactly how teh screw machine guys do it but I am close and htis is the CNC forum anyway). 2500 RPM sounds OK the only problem I see is changing from the tap to the drill with the spindle going that fast. You will loose a lot of time if you stop the spindle each time to change tools so you have to be FAST on the tool change.

Also if that is 4000 holes in one work piece you may have fixturing problems on your mill.

cybergomer · Apr 1, 2014

While on the topic of left hand drills. Do they replace the material previously removed from a right hand drill? (Honest to god, that was a test question at our local college)

CAPCNC · Apr 1, 2014

michiganbuck · Apr 1, 2014

Davis In SC said:
Unless I am missing something/misinterpreting the question..... A hole is a hole, as long as it straight, with a decent finish, Be it drilled, wired, bored, or what ever.. RH drill is fine..

RH drill is fine? Only when one is sharp.

But then are fine drills only for fine threads?

And... if one Left the drill in the chuck where would you put the tap?

Oh yes... in the hole.

Nick Mueller · Apr 1, 2014

If you need RoHS certificates for that part:
Be warned! You have to precisely separate the LH-swarf from the RH-swarf and label the LH-swarf before sending it to the scrapper!

So doing both ops LH is way less hassle.

Nick

michiganbuck · Apr 1, 2014

Some US scrappers won't even accept Metric thread swarf at all and it ends up left on the curb. Does anyone think that is right?

SIM · Apr 1, 2014

I prefer using Fluteless drills for those jobs.

Mickey_D · Apr 1, 2014

Works great if you run straight Moly-Dee for coolant. It is a little hard on the pumps, but the holes pretty much drill and tap themselves.

michiganbuck · Apr 1, 2014

SIM said:
I prefer using Fluteless drills for those jobs.

Don’t know much about fluteless drills but you never see a piano in an Army band.

Flutes yes / piano...no

bic · Apr 1, 2014

michiganbuck said:
Don’t know much about fluteless drills but you never see a piano in an Army band.

but a cello in a marching band... Take the Money and Run- Marching Band Scene - YouTube

scadvice · Apr 1, 2014

cybergomer said:
While on the topic of left hand drills. Do they replace the material previously removed from a right hand drill? (Honest to god, that was a test question at our local college)

I could use a few of those...do they make them in an end mill?

MachEng · Apr 1, 2014

It Depends if you are in the Northern or Southern Hemisphere

mach2 · Apr 1, 2014

Safarir said:
You can use a right hand drill bit but you need to flip you mill upside down. 2.5amps is the theorical limit rpm of your motor, just plug you servo directly in your wall power outlet. If you are in the us, that is 115v so 115000 rpm. You should be able to do all your holes in less than a minute. At this speed, you can use tapping oil but peanut butter is much better

Grape jelly gives the best finish and if used with the peanut butter the drill bit, er twist drill won't get stuck in the hole.

Can I use a right hand drill for a left hand tap?

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