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4-40 taps

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dlane

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#1
I’ll be starting a project requiring two 4-40 taped holes in 6061 aluminum 1.5” deep thru hole , 40total
I tried google search for reduced shank 4-40 taps , didn’t turn up anything that would go that deep , any suggestions ?, coatings?
I have a tapmatic that I was thinking of power taping them.
Also remind me about H2-H3-H5 threads
Thanks
 

Tinkertoy1941

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#2
I would suggest a redesign because I think that you can not use the whole 1.500 length of thread.
If the thread has to go through the bottom side open the top side for tap shank clearance.
Need more info
 

dennys502

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#3
Do you need threads on both sides of the plate? One side could be drilled larger. H1 is basic pitch to .0005 plus - add .0005 as you go up.
 

Tinkertoy1941

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#4
Another thought from eBay!
1528564240152.png
You could grind this pulley tap down to just clear the threads.
 

FLguy

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#7
Ought to work well. That company, I have bought from several times, fast delivery. You could have offered less than their stated price and if with in reason they often accept your bid.
 

markba633csi

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#8
Be prepared to snap a tap or two trying to tap 4-40 threads that deep. Aluminum is "gummy" and tends to grab. Use plenty of tapping fluid. If you can change the design to make the thread shallower (both width and depth) it would make the job easier
 

mksj

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#9
You would not use a spiral point tap if this is a blind hole, if a through hole then they would be appropriate. A spiral flute is used on blind holes. You want a short threaded tip, the spiral point will move the chips forward, the spiral flute will pull them back out. Use cutting fluid, if power tapping then make sure the tap alignment to the hole is spot on. If the tapped thread can be a partial, you may be able to drill a slightly larger hole for tapping and do a partial thread, a #43, 2.3 mm or a 3/32 drill are very slightly oversized.
thread chart.jpg
4-40 H2 2 Flute 4" HSS V3 Spiral Flute Bottoming Tap, looks like the it might do threads to 1.5".
https://www.suncoasttools.com/crm/ItemPage.aspx?ItemNumber=800.112040+G9162++YG&VendorNumber=YG1TOOL
taps.jpg
This tap is specific for aluminum but the tap depth may be an issue.
https://www.suncoasttools.com/crm/ItemPage.aspx?ItemNumber=800.112040+C0162++YG&VendorNumber=YG1TOOL

The application or design may help others suggest maybe a redesign or alternative solution. I will often tap the bottom of the hole and then use a shoulder which is larger for the top part of the hole. I cut the matching shank and threaded tip to match. The type of aluminum can also make a significant difference, I assume this is 6061?
 
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Glenn Goodlett

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#10
I think I'm only good for about 80% on tapping 4-40, so, I would plan on some broken taps and scrapped parts.

Best of luck
 

dlane

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#11
The hole is taped all the way thru so a 4-40 set screw Locks the top button head screw with a Belleville washer under it,
To keep downward pressure on a rotating aluminum top. I’ve made these before after grinding the tap shank to clear the threads but that tap is wore out. I have a taping fixture or a tapmatic 1a I’m hoping to use.
This is California if you want to see a design pm me.
Thanks for the help, advice, thoughts
 

Kernbigo

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#12
in aluminum use a x-press tap
 

Kernbigo

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#14
Thread forming and x-press are the same thing,that is what they were design for soft material,Besly design that tap when I worked there

Sent from my SM-G900V using Tapatalk
 

dlane

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#15
Not familiar with those taps , hopefully the ones I ordered will work ok.
 

pdentrem

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#16
I see that x-press tap is a company product name. Another piece of info to file away for future use.
 
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