Tapping essentials

ammoody
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Tapping essentials

Post by ammoody » Sun Sep 28, 2014 6:22 pm

There is a lot of info on the build instructions about tapping, but I still had some difficulty despite this fact. I've also performed tapping in the past (on steel only), but this experience didn't really help as much as I expected. Aluminum is a tricky little metal. It woos you in with its softness then bites you when you least expect it.

LUBRICATION IS NOT OPTIONAL. WD-40 works great. And if you're like me, you've got at least six cans of it in varying amounts lying around your garage. Just one spray down the hole before you start should be fine. I sprayed the tap between each attempt as well, to wash out the scraps.

If you don't lubricate (and you're reading this after you've destroyed a bolt hole or two in your MakerSlide), the dry Aluminum will gall your tap. What this means is, the friction of the tap against the chips causes it to weld Aluminum into the threads of the tap, rendering it useless. You'll likely destroy whatever hole you're tapping when this iccurs, as the galled threads will undo all of your work on the way back out. You'll need to tap a bigger hole to reclaim the MakerSlide or buy a new one.

To reclaim your tap, you'll need to get the Aluminum out of the threads. This isn't possible mechanically (as far as I'm capable, anyway). You'll need to chemically remove the Aluminum from the tap. Best way to accomplish this is to buy some generic drain unclogger from your local grocery store. Make sure it has ([EDIT] sodium) hydroxide as one of the active ingredients. This is the chemical that's going to do our work for us. Using a glass jar with a lid, pour enough to cover the tap, drop the tap in and let it soak overnight. It makes for a really neat show, as you can watch the Aluminum dissolving right before your eyes. Be careful when you open the jar, as it creates a potentially dangerous chemical if you breathe a lot of it. Open it outdoors to be safe.

I also found that the stainless steel tap that ships with the kit isn't very sturdy. Mine was dull after about 8 holes. I bought a metric tap kit from the local auto store pretty cheaply that featured carbon steel taps (M5x0.8 is required). This one seemed to cut much easier and was still going strong after finishing the holes for the kit. I even tapped the wasteboard mounting rails (accidentally, because I didn't read the list of holes and just tapped everything in sight, once I got going).
I hope this informaton is helpful. If you have anything to add, please post it.
Last edited by ammoody on Tue Sep 30, 2014 12:14 pm, edited 1 time in total.

Gadgetman!
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Re: Tapping essentials

Post by Gadgetman! » Sun Sep 28, 2014 8:34 pm

Pretty certain this belongs in the Wiki, or at least the 'Get Help!' / 'Assembly' section...

Anyway, WD40 belongs in the 'better than nothing' category when it comes to lubricating the tap.
A spray can of a decent cutting oil isn't all that much more expensive than WD40.
(It's also useful when drilling steel or other metals, or a number of other machining operations... )
Weird guy...
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ammoody
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Re: Tapping essentials

Post by ammoody » Mon Sep 29, 2014 12:09 am

[EDIT] Rant removed by OP. I misunderstood the tone of the reply and went off the rails for a bit. Didn't think it needed to stay intact and plague the forum.
Last edited by ammoody on Mon Sep 29, 2014 10:27 pm, edited 1 time in total.

WillAdams
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Re: Tapping essentials

Post by WillAdams » Mon Sep 29, 2014 12:44 am

I believe that Gadgetman!'s comment was noting the good quality of your post and intended as a note to me that I should bestir myself to copy the content to the wiki.

I don't believe it was intended to criticize you for posting things here --- that's what this forum is for and how you went about building your machine is certainly on-topic for Build Logs.

I strongly advocate for lubricant everywhere tapping is discussed, and there's also a link to using kitchen chemistry to extricate a broken tap. I think we also mention using chemicals to clean endmills somewhere
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Woodworker
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Re: Tapping essentials

Post by Woodworker » Mon Sep 29, 2014 1:11 am

Last time I checked "Pretty certain this belongs in the Wiki" is a positive comment. It indicates that there was valuable information and is should be preserverd.
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Gadgetman!
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Re: Tapping essentials

Post by Gadgetman! » Mon Sep 29, 2014 8:22 am

My post wasn't meant as a criticism, just an observation that that's where I expected to find this information.
I sometimes make posts that can be seen as criticism without meaning to. It's a bad habit of mine that I can't seem to shake off. If I ever post another where this may be the case, PM me and ask, and I'll fix it as soon as possible.
(I get email notification of PMs, so can respond reasonably quickly)

The stuff about dissolving the aluminium was new to me, and quite interesting.
Weird guy...
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cvoinescu
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Re: Tapping essentials

Post by cvoinescu » Mon Sep 29, 2014 9:06 am

"This belongs to the Wiki" means "thanks, dude, that was so helpful that we need to put it where it's easier for others to find".

If you hang around, I think you will find this small corner of the Internet to be way more civil and polite than average.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

ammoody
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Re: Tapping essentials

Post by ammoody » Mon Sep 29, 2014 9:54 am

Sorry, guys. I've been a little on edge lately and apparently took the response out of context. Thanks for sticking with me and turning me around.
I'll try to be a little less sensitive in the future.

I did try to edit the wiki and include this, but it seems I'm doing it wrong.

What oil do you recommend? I'm planning to do some aluminum cutting with the Shapeoko and thought that WD-40 should do the trick, but if there's something better, I'd like to give it a go.

cvoinescu
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Re: Tapping essentials

Post by cvoinescu » Mon Sep 29, 2014 10:31 am

I use "cutting and tapping oil". It's a little thicker than WD40, and a nasty brown color. Mine is an aerosol can, but it can also be bought in a bottle, without propellant. I think I just searched for "tapping oil" (or "cutting oil", I don't remember) on eBay, and bought whatever seemed good value.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

ammoody
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Joined: Sat Sep 27, 2014 10:06 am

Re: Tapping essentials

Post by ammoody » Mon Sep 29, 2014 10:43 am

@Will: I know you guys mention lubricant in the wiki and anyone slightly more diligent than myself would have taken heed, but like I said, Aluminum is tricky. In my head, it was so soft that I didn't need lubricant to help the tap make its way through the metal (yes, this was a silly conclusion). The wiki lists how lubricant is helpful for this or that, but some of us hard heads need it spelled out. I wasn't implying that the wiki was deficient, just that it didn't spell out the dangers of not heeding the lubricant. And I like to reinvent the wheel.

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