Just got a Tapmatic... Washed out threads??

REK Knives

REK Knives

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Knifemaker / Craftsman / Service Provider
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So I was super excited to get my tapmatic in yesterday, and it is amazing how fast it taps holes! But I can't figure out why I'm getting the peaks coming out as flat at the entrance of the holes I'm tapping. At the exit they aren't nearly as bad. Here are 2 comparison pics... top one is the washed out threads, bottom is one that I hand tapped. Anyone seen this before?

i-hXmGhT6-X2.jpg
i-8pM898B-X2.jpg
 
I'm making the assumption you used the same drill bit to drill holes and same tap? Interesting, hard to comprehend how that could happen. Photos proof - I don't have a clue.
 
Explain your process an show us the tap style you are using. I tap a lot of holes in annealed 01 that is 9/32 thick, thousands of them, I've never seen this condition.

Fred
 
Thanks for chiming in and trying to help me guys. So I'm tapping an M5x.8 thread in combination with using a 4.2mm bit to drill the hole (as this chart specifies). The tap I'm using is this one, a general purpose tap for starting threads. It was just interesting to me how the hand-tapped threads seemed much sharper than the ones done w/ my tapmatic. Anyway, I'm just using both the bit and tapmatic in a benchtop Ryobi drill press, so it's not a mill or anything and does have a little bit of run out - which with the long 6" tapmatic is much more evident at the tap end of things - this may be my problem...? Oh and I'm clamping my parts while drilling and tapping then using some tapmagic cutting oil.

Yes I did buy this used off of ebay, but I just fully disassembled and reassembled it to see if any of the interior parts appeared worn. They all looked to be in extremely good shape w/ no metal shavings or anything inside, and well lubed.

I did realize one thing I needed to do was grind off the point on the end of the square part of the tap so it can fully seat in the back-jaw.

Anyway after disassembling/reassembling and doing this it doesn't seem to be quite as bad, although I still have some flatness on the peaks.

Here's a few pics disassembled...

i-9C3f35S-X2.jpg
i-6W4Tk4s-X2.jpg
i-xRG8z4f-X2.jpg
i-8Xk7Mm6-X2.jpg
 
I'm assuming you're plunging close to the full length of the tap into the piece before reversing the head?
 
The tapmatic is a great tool, once I made 300+ 1/4" threads in less than 2 hours, amazing.
Are you 100% sure the hole was not oversize? it looks like the tap barely touched it, and we all know a tap will break if forced a bit too much. Oversized hole is the only explanation that comes to mind after seeing the first post photo.


Pablo
 
Do you have a calipers?

I would be checking your drilled hole for taper before blaming the tapping process. Generally taps do not flatten out thread crests when there is run out or other issues. Flat crests in my experience mean the drilled hole was too large. Easy to check, anyway.
 
A worn-out Tapmatic is a loathsome thing. We had one at my old day-job and it was feared and hated.

Run-out and minor misalignment isn't a concern - the tapmatic rubber collet is meant to compensate for that.

It may be the lighting, but your hand-tapped hole doesn't look too great to me either.

Barring pin gauges and other precision measuring tools, the best diagnosis may be the wiggle-test - i.e. insert the mating bolt/screw by hand and see how much wiggle you get. Compare the wiggle to a high-quality off-the-shelf nut.

The #1 rule with a Tapmatic is don't baby the entry or exit. Upon exit, you should be 'ahead' of the tap - i.e. let the Tapmatic's springs pull the tap out of the hole. Don't let the tap push the drill chuck up.
 
I'm going with a Knife to a Gunfight on this one. It looks like it's only starting to cut the threads and then reverses. Wish I had a tapmatic, I still use a cordless drill instead.

You realize then hand taps and machine taps aren't necessarily the same? Hand taps are designed to strat, stop, reverse, repeat over and over. Machine taps will look more like a threaded drill bit. I prefer the kind with a much thicker core.
Machine_Taps.jpg
 
knife to a gunfight said:
I'm assuming you're plunging close to the full length of the tap into the piece before reversing the head?
Click to expand...

Well I've screwed the torque cap a good bit past 10 and the tap only makes it through up to about 1/2-3/4 of the tap before stopping, unless I back it out and go in and out a few times then it will go the full length. Maybe I need to try to tighten the torque cap more...In this case I'm tapping .187" thick annealed 1095.

PEU said:
The tapmatic is a great tool, once I made 300+ 1/4" threads in less than 2 hours, amazing.
Are you 100% sure the hole was not oversize? it looks like the tap barely touched it, and we all know a tap will break if forced a bit too much. Oversized hole is the only explanation that comes to mind after seeing the first post photo.


Pablo
Click to expand...

No, I'm not 100% on this because I didn't double check w/ my caliper but I will now! Thanks for the suggestion, that was my first thought but I dismissed it. Now that I'm having issues I can't dismiss any possiblity.

kuraki said:
Do you have a calipers?

I would be checking your drilled hole for taper before blaming the tapping process. Generally taps do not flatten out thread crests when there is run out or other issues. Flat crests in my experience mean the drilled hole was too large. Easy to check, anyway.
Click to expand...

Yes I do... and thank you for the suggestion, I will definitely do this!

P.Brewster said:
A worn-out Tapmatic is a loathsome thing. We had one at my old day-job and it was feared and hated.

Run-out and minor misalignment isn't a concern - the tapmatic rubber collet is meant to compensate for that.

It may be the lighting, but your hand-tapped hole doesn't look too great to me either.

Barring pin gauges and other precision measuring tools, the best diagnosis may be the wiggle-test - i.e. insert the mating bolt/screw by hand and see how much wiggle you get. Compare the wiggle to a high-quality off-the-shelf nut.

The #1 rule with a Tapmatic is don't baby the entry or exit. Upon exit, you should be 'ahead' of the tap - i.e. let the Tapmatic's springs pull the tap out of the hole. Don't let the tap push the drill chuck up.
Click to expand...

Yeah I thought the rubber collet may compensate for the run out as it seems to stabilize when going in and out of the hole. I don't think I've 'babied' it, I make sure it starts with firm pressure but let the tap lead and me follow (as the instructions say) then reverse it quickly slightly ahead of the tap as you say.

Atlas Knife Company said:
I'm going with a Knife to a Gunfight on this one. It looks like it's only starting to cut the threads and then reverses. Wish I had a tapmatic, I still use a cordless drill instead.

You realize then hand taps and machine taps aren't necessarily the same? Hand taps are designed to strat, stop, reverse, repeat over and over. Machine taps will look more like a threaded drill bit. I prefer the kind with a much thicker core.
Machine_Taps.jpg
Click to expand...

I didn't realize there was much of a difference... thanks for pointing that out. I will have to look into getting a different tap for this process.
 
razor-edge-knives said:
Well I've screwed the torque cap a good bit past 10 and the tap only makes it through up to about 1/2-3/4 of the tap before stopping, unless I back it out and go in and out a few times then it will go the full length. Maybe I need to try to tighten the torque cap more...In this case I'm tapping .187" thick annealed 1095.
Click to expand...

For only 3/16" material, I'd think 75% of a standard tapered tap would be enough for a full thread, BUT then again, under ideal operation, your tapping head shouldn't reverse unless 1) the tap bottoms out, 2) the quill is retracted.

Once the tap cuts a FULL thread, it should be nothing for the tap to continue down all the way to the shank.

If you hand thread the tap on the flat threads in question, does it continue cutting? I'd chase those bad threads all the way down to the tap shank and THEN see what they look like.


Sent from my iPhone using Tapatalk
 
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