Newbie Question About Taps

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David Carter · #1 Post by **David Carter** » Tue Dec 11, 2007 4:06 pm

I've never used a tap before, but I bought a 10/32 tap to have on hand for mounting drivers in my DR250's. I'm sitting here holding some 10/32 hurricane nuts in my hand trying to get a feel for the tap, and I'm puzzled. I can run my bolts through the h-nuts with no problem, but I can't get the tap to go through. It gets hung up right from the start. I've tried and tried to maneuver it around to make sure it's properly aligned with the threads in the h-nuts, and I cannot get it to work!

Is there some trick to this that I'm not aware of...?

asad137 · #2 Post by **asad137** » Tue Dec 11, 2007 4:09 pm

No, no trick -- a tap should run easily through a corresponding tapped hole. Are you sure you didn't accidentally get a 10-24 tap instead of a 10-32?

Asad

David Carter · #3 Post by **David Carter** » Tue Dec 11, 2007 4:13 pm

asad137 wrote:No, no trick -- a tap should run easily through a corresponding tapped hole. Are you sure you didn't accidentally get a 10-24 tap instead of a 10-32?

I wondered about that, but I've double checked that packages for both the tap and the hurricane nuts, and they both say 10-32.

asad137 · #4 Post by **asad137** » Tue Dec 11, 2007 4:17 pm

The only thing I would check just to make sure is compare the thread pitch on one of the bolts to the thread pitch on the tap (just try and get the threads to nest). And check the diameter of the tap -- if it's a 2 or 4-flute tap, you should just be able to measure across the thread crowns. A 10-32 tap should have the just about the same diameter as a 10-32 screw. Who knows, maybe the package was mislabeled?

Asad

LelandCrooks · #5 Post by **LelandCrooks** » Tue Dec 11, 2007 5:59 pm

The taps are much more precise than the bolt or the nuts. Any snag or burr will make it hang. Use a t handle to hold the tap, make sure you're perpendicular, and tap away. Do double check to make sure the tap threads mesh with the bolt.

I tap every hurricane after installation. They usually cut a little on every one. You'll feel it ease off after it bites through whatever the problem is. Running taps and dies is a matter of feel. They are hard and brittle, and nothing is worse than a broken tap in a screw hole.

I'm always amazed at machinists tapping a hole with a drill press.

WB · #6 Post by WB » Tue Dec 11, 2007 6:09 pm

I always use spiral taps now. So much nicer to work with and not as prone to breaking.
These taps are made with spiral flutes instead of straight flutes. This spiral fluting feature helps in drawing chips out of a hole, or jumping a gap inside the hole such as a keyway or cross-hole. I little bit of cutting fluid is good to use as well.

spiral taps

David Carter · #7 Post by **David Carter** » Tue Dec 11, 2007 9:50 pm

LelandCrooks wrote:The taps are much more precise than the bolt or the nuts. Any snag or burr will make it hang. Use a t handle to hold the tap, make sure you're perpendicular, and tap away. Do double check to make sure the tap threads mesh with the bolt.

Leland, I think you win the prize this time. I had been trying to spin the tap through the h-nut by just holding the h-nut with my fingers and spinning the tap (with T-handle) through it with my other hand. It got caught every time. However, I just finished trying it on some scrap wood by pulling the h-nut into a 1/4" hole and then tapping it. I met a lot of resistance at first, but I forced the tap through, and, after cutting away quite a bit of material, the tap now goes through without a problem, and the bolt that I could twist through with my fingers before tapping now spins effortlessly through the newly tapped h-nut.

Thanks!

David Carter · #8 Post by **David Carter** » Wed Dec 12, 2007 12:46 pm

I'm starting to think that my tap isn't quite right. I got the cheapest one that I could find at Lowe's and a T-handle to go with it, and I've noticed that the T-handle never wants to hold the tap straight. I'm also not sure the shaft is completely straight on the tap to begin with. Anyway, I think that may be one of the reasons I was having trouble. Because I can never get it to go in completely straight.

I drilled holes and installed h-nuts in my baffle and spacer with 5-minute epoxy this morning. Not sure if I used enough epoxy, but I think I did. After letting everything sit for 15-20 minutes, I tried to tap the nuts and spun the first three I tried. I have reinstalled the nuts with Gorilla glue to get it to expand around the shaft better than the epoxy. Now I've got to get a better tap. I think I'm going to go ahead and at least trial mount the driver anyway to check hole alignment.

Wish me luck!

WB · #9 Post by WB » Wed Dec 12, 2007 1:07 pm

David Carter wrote:I tried to tap the nuts and spun the first three I tried.

Personally I'm never using T-nuts, or Hurricane nuts ever again. Once you spin one that hole is a lost cause as far as I concerned. One is enough to ruin a day, sorry to hear about your three. I have a diy alternative idea in mind that will be 100% foolproof for my next project.

brodave2 · #10 Post by **brodave2** » Sat Dec 15, 2007 8:39 am

I've been a machinist for 34 years. Most threaded fasteners you buy have rolled threads. Rolled threads do not have the sharp "V" that cut threads have. To run a tap through a rolled thread you usually have to cut the sharp "V" in the bottom of the thread, so there will be some resistance the first time through. The corresponding threads on the screw go easily because they are rolled also, they don't have a sharp "V" at the top of the thread. Rolled threads are stronger because they don't have the sharp "V" which is a stress riser. Many large machines have rolled threads on critical parts, and if you run a die nut over those threads, the part has to be replaced because you induced stress risers into the threads, and the part will break prematurely there.

fender3x · #11 Post by **fender3x** » Sun Dec 16, 2007 4:27 pm

David Carter wrote:Not sure if I used enough epoxy, but I think I did. After letting everything sit for 15-20 minutes, I tried to tap the nuts and spun the first three I tried. I have reinstalled the nuts with Gorilla glue to get it to expand around the shaft better than the epoxy. Now I've got to get a better tap. I think I'm going to go ahead and at least trial mount the driver anyway to check hole alignment.

Wish me luck!

I wish you luck! I wish I had seen this earlier... I spun a hurricane nut in a baffle hole in one of my test runs. I don't think it's a good idea to just reinstall the nut after you stripped out the wood around the shaft... H-nuts bite into the wood and that's part of what holds them in place.

Once again, this is a place where dowels came to my aid. In the hole where the h-nut spun, I drilled a 1/2" hole, and put a 1/2" dowel in it, then re-drilled the hole for the h-nut. That way it had a nice, new, snug, hardwood hole for the H-nut to bite into.

Once done drilling, I also sprayed the hole with a fine mist of water, then used Gorilla glue and then let it sit overnight.

This is also the reason that (as I put in some other thread), I tighten the driver down gradually, three turns on each bolt at a time, making several circuits around the driver before it is down tight.

David Carter · #12 Post by **David Carter** » Sun Dec 16, 2007 8:18 pm

fender3x wrote:
David Carter wrote:Not sure if I used enough epoxy, but I think I did. After letting everything sit for 15-20 minutes, I tried to tap the nuts and spun the first three I tried. I have reinstalled the nuts with Gorilla glue to get it to expand around the shaft better than the epoxy. Now I've got to get a better tap. I think I'm going to go ahead and at least trial mount the driver anyway to check hole alignment.

Wish me luck!
I wish you luck! I wish I had seen this earlier... I spun a hurricane nut in a baffle hole in one of my test runs. I don't think it's a good idea to just reinstall the nut after you stripped out the wood around the shaft... H-nuts bite into the wood and that's part of what holds them in place.

Once again, this is a place where dowels came to my aid. In the hole where the h-nut spun, I drilled a 1/2" hole, and put a 1/2" dowel in it, then re-drilled the hole for the h-nut. That way it had a nice, new, snug, hardwood hole for the H-nut to bite into.

Once done drilling, I also sprayed the hole with a fine mist of water, then used Gorilla glue and then let it sit overnight.

This is also the reason that (as I put in some other thread), I tighten the driver down gradually, three turns on each bolt at a time, making several circuits around the driver before it is down tight.

Thanks for the additional tips. I used Gorilla glue the second time around on the ones that I spun, and I was able to successfully mount the driver by gradually hand tightening the bolts a little at time. No spun nuts during the trial mounting. I hope it continues to hold up once I'm doing it for real!