Tapping aluminium

1

Anyone here has experience with tapping?

I have to tap a few hundred holes for a small series production.

The thread size is M3 and the depth is 1/2 inch or 12.7 mm.

I used to cut them on my drill press with a tapmatic, which works very well but is very time consuming, I would take me more than a day to tap 400 holes.

It just came to my mind that VCarve has a thread cutting function. I do have a mister that blows isopropanol for chip evacuation and cooling.

What are the feeds and speeds?

Do I need a low RPM spindle?

Is the Onefinity rigid enough?

What kind of thread cutter should I use?

I was thinking to use a 2mm cutter and use the pocket toolpath and spiral down to pre-drill the hole.

2

Vetric thread cutting won’t work for your application. There is no cutter small enough.

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3

@Aiph5u found a thread cutter for me that works, thanks!

It seems true that there is no end mill to cut a spiral pocket that is small enough to cut the 2.5mm hole that I need.

I will have to rely on peck drilling.

I will hopefully have the Redline soon, the min RPM is 8000 rpm.

It looks like I will have to use a cobalt 2.5 mm drill.

If anyone has any info on where to get feeds and speeds please let me know.

I know 8000rpm is not ideal and hope this is feasible.

I might even consider buying a different spindle.

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4

Harvey has some small endmills if you want to circle mill the holes. I would recommend drilling them as circle milling will take a long time. Feeds and speed on a carbide drill 8000rpm and 16 ipm, but I would start at about half that feedrate just to be safe then bump it up depending on how it sounds. I would look at outsourcing the parts to see what you can get them done for before investing time and money. You might be surprised to find someone cheap enough that you can still make a profit.

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5

Or look at one on the cheap flex pneumatic tapping arms as an option.

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6

Little more info on these, perhaps?

7

Couldn’t he twist drill or down spiral the holes and then thread it with something like this? Aren’t these for threading at higher speeds and without reversing?

I don’t know :poop: about :poop:, just trying to learn here.

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8

Yes, to cut the M3 thread this bit should work.

My problem is to cut the 2,5 mm hole that is needed first.

If the hole was bigger I would use an end mill and spiral helix down.

But I did not find an end mill that is that small (2mm) and can cut 12.7mm deep.

It just came to my mind that I might not have to cut all the way through the material, I might be ok with a blind hole.

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9

Google “flex arm tap” and a bunch will show up, from $400 to $2500. we have one in the shop, has collets for the taps sizes. Ours can tap anything up to 3/8", but u can get them to do over a 1" tap.

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10

Very cool. Also, one more thing I didn’t need to know existed. Now I need one of those, too.

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11

IMO, if you have the tapmatic available I would use that (assuming it will go down to that size tap). As cool as it would be to machine in the threads with a threadmill, I think you would have to babysit the size with a thread gage to ensure they are holding size (not too big or too small).

BTW, are these thru holes or blind holes? A standard M3 tap may have an issue getting a full 1/2" of thread.

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12

OMG this might be an actual informed answer.

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13

Yes, I can always fall back on the tapmatic. It just takes a long time to tap hundreds of threads manually.

I used to make a through hole which is easier on the tapmatic due to better chip evacuation, but thinking about it now It seems best to have a blind hole should I go down the route of using my 1F.

I used to outsource the manufacturing to a company that has a water jet CNC. However the quote for additional tapping had been very expensive, the only affordable way was to do that in house.

I want to try to do both profile cut and tapping on one machine myself in one go, which would save me a lot of time standing at the drill press tapping and I would not have to pay the water jet company either.

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14

I was in a similar situation.

I ended up getting one of these:

https://www.aliexpress.us/item/3256806124353117.html?spm=a2g0n.productlist.0.0.49e362e2vAl7Gf&browser_id=c3453109e16f48cb8726caee04aa552c&aff_platform=msite&m_page_id=tvmimrsxzcaatbvo1966944f8a84a06e45a8dbcb12&pdp_ext_f={"order"%3A"23"%2C"eval"%3A"1"}&pdp_npi=4%40dis!USD!1126.71!597.16!!!1126.71!597.16!%402103247917455228499408630e7cb0!12000036711488908!sea!US!6177368224!X&algo_pvid=72fc7021-0262-4b88-8b49-e24b096581f7

It’s amazing. I tapped about 500 1/4-20 holes in about 2.5 hours.

I hate tapping by hand more than anything. This tool is a lifesaver.

15

If you have a lot of tapping to do this is the way to go.

16

Tapping aluminum efficiently can be a challenge, especially for a large number of holes. Here are some suggestions based on your setup:

  1. Feeds and Speeds: Aluminum typically requires higher speeds. For M3 threads, around 1000-3000 RPM is common, but it heavily depends on your specific machine and tooling.

  2. Spindle RPM: A low RPM spindle can reduce the risk of broken taps, but if your equipment supports it, a mid-range RPM often provides a good balance.

  3. Rigidity: Ensure the Onefinity CNC is properly secured and calibrated. While it’s not the most rigid, it may suffice for aluminum with light, calculated cuts.

  4. Thread Cutter: Consider spiral flute taps for aluminum. They help evacuate chips efficiently.

  5. Pre-drilling: A 2mm cutter can work, but ensure it’s sharp and well-suited for aluminum to minimize tool wear.

Testing on scrap material first can help find the optimal setup.