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Feb 21, 2020, 07:13 PM
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I have a broken tap in a glass filled motor mount. I wonder if the alum would work with it. Of course I don't have to get it out because I just moved the motor a little and started over.
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Feb 21, 2020, 09:59 PM
Registered User
Quote:
Originally Posted by earlwb
sulfuric acid works well too. About 10% by volume. Lead battery acid is sulfuric acid, Professional plumbers use it to unclog drains too. You do need to test it on a section of the aluminum just in case as some aluminum alloys have a lot of zinc or copper etc mixed in and it may pit the surface or discolor it.

Alum can be found in the grocery store spices section. You want to test it on the part, just in case too.
Yes we do use sulfuric acid for drain cleaning. Not a chemical to be used lightly, it is serious stuff. It has put me in the hospital.
Feb 22, 2020, 12:15 AM
Diesel Danny
danny mz's Avatar
Quote:
Originally Posted by Gary Cee
Lack of the correct lube is a major cause of broken taps in aluminum.
LOL. I used a decent lube for Aluminium (kerosine). Problem was that I allowed the tap to bottom out in a blind hole.

Just a stupid operator error
Feb 22, 2020, 07:08 AM
One of the worlds best hobbies
Gary Cee's Avatar
Quote:
Originally Posted by danny mz
LOL. I used a decent lube for Aluminium (kerosine). Problem was that I allowed the tap to bottom out in a blind hole.

Just a stupid operator error
I was actually asking the OP.
Plenty of people who fail to use a good tapping fluid.

Almost always get inferior threads and often get broken taps. Many different alloys, some more critical than others. Aluminum can have quite an affinity for steel. Dull taps and dry taps can easily clog and bind.
https://itstillruns.com/drill-tap-aluminum-7524509.html
Last edited by Gary Cee; Feb 22, 2020 at 07:22 AM.
Feb 22, 2020, 11:06 AM
Registered User
I was taught when tapping aluminum to turn it about 1/2 a turn and then back up to break the thread loose. You don't build up any heat that way.
Feb 22, 2020, 11:18 AM
Still gassin' it.
Quote:
Originally Posted by JimboPilotFL
I was taught when tapping aluminum to turn it about 1/2 a turn and then back up to break the thread loose. You don't build up any heat that way.
Yup... Basically, every material, not only Aluminium. Never broken a tap in Aluminium that way, regardless of which alloy I came across, be that cast, sheet or bar stock.
Does not mean I have tapped in every possible alloy out there, but every one I had to work on, never encountered problems.

I found Copper to be more problematic.
Feb 22, 2020, 11:35 AM
One of the worlds best hobbies
Gary Cee's Avatar
Quote:
Originally Posted by JimboPilotFL
I was taught when tapping aluminum to turn it about 1/2 a turn and then back up to break the thread loose. You don't build up any heat that way.
Yep, back and forth, hand tapping usually with a four flute tap. To get good threads, save tap wear as well as minimize breakage, tapping fluid should be employed in that case as well. Dry taps tend to tear metal away rather than cut cleanly. We have seen many cutaways of improperly formed dry threads . Sharp cutters, proper fluids and correct cutter geometry make for well formed threads that hold far better than sloppy, hacked threads.
Doing deep, blind holes, the tap should be a chip lifting type preferably . Failing that, it should be periodically fully withdrawn and the chips removed from the hole.
Dry tapping aluminum is just plain poor practice. Thin sections are not all that fussy but the threads are far better formed using the correct methods and materials in every case.

Doing the job correctly pays in the long run.

"Hundreds of holes" perhaps in the first hour or two! LOL, like that is a lot?

Do as you will, it is "just a hobby" .
Last edited by Gary Cee; Feb 22, 2020 at 11:40 AM.
Feb 22, 2020, 01:30 PM
AMA 46133
SeismicCWave's Avatar
I hate tapping holes.

Over the last 50 years I have learned the hard way. Proper cutting fluid is a must in tapping metal. WD-40 is NOT a proper cutting fluid.

Another factor I have learned is that my hand is never turning the tap perfectly straight. I broke enough 2mm tap to figure that one out. A side load while turning the tap is a broken tap waiting to happen.

As much as possible I use my lathe to tap. I also bought this cheap tapping machine and that helped tremendously. Knock on wood, so far so good.

A bottle of good cutting fluid, a good tapping machine, turn a little and back it out, clean and repeat. Patience, patience, patience. This hobby is all about patience.
Feb 22, 2020, 01:48 PM
Registered User
When possible, I Chuck taps in my drill press and manually turn them. The drill press keeps them perpendicular to the work surface.

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Feb 22, 2020, 01:53 PM
AMA 46133
SeismicCWave's Avatar
Quote:
Originally Posted by raleighcopter
When possible, I Chuck taps in my drill press and manually turn them. The drill press keeps them perpendicular to the work surface.

Sent from my Pixel 2 using Tapatalk
That's definitely one way to do it. The only issue I see with that is the drag of the drill press. The drag of the drill press can mask the resistance of the tap. So I can turn a but too hard not being able to feel the resistance.

Same thing with the lathe. The gear resistance mask the drag of the tap.

Perfectly fine if the tap is a reasonable diameter. The smaller the tap the more delicate the operation.
Feb 22, 2020, 02:19 PM
Registered User
I at least get the tap started with some sort of device to keep it perpendicular. Once started, unchuck it and use a normal tap handle. Whatever works to not break the tool.

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Feb 22, 2020, 02:20 PM
Registered User
...I also remove the belt from the sheaves in my drill press when I do that to reduce the drag

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Feb 22, 2020, 02:23 PM
Registered User
Have you seen these drill, tap and countersink things??? Very strange.

https://www.amazon.com/HUELE-Drill-C...ustrial&sr=1-3
Feb 22, 2020, 03:23 PM
Registered User
Buy 3 sets because they look like they're going to break a lot.

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Feb 22, 2020, 05:00 PM
///////
coriolan's Avatar
Quote:
Originally Posted by JimboPilotFL
Have you seen these drill, tap and countersink things??? Very strange.

https://www.amazon.com/HUELE-Drill-C...ustrial&sr=1-3
Trying to do everything with one tool end-up doing noting well


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