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Broken Tap/Knuckle trying to install dubros

Broken Tap/Knuckle trying to install dubros

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Old 01-08-2016, 09:53 AM
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Default Broken Tap/Knuckle trying to install dubros

Hi everyone!

Quick backstory.

So I just got into the hobby over xmas break. Spent a bunch of money 3 cars and hop ups already for the mini-z, losi micro scte, as well as the micro-t I bought.

After breaking every single one of those crappy plastic tie rods on both the scte and micro-t, as well as the many replacements I made from gift cards after learning about that... I found some solutions on various boards such as this one and microtforums (which I can't get my account activated at to post anything for some reason).

Anyway, after deciding to go with the dubro solution and reading up on the things I'd need. I bought the 0-80 tap, 0-80 threaded rod, enough dubros for both the scte and micro-t as well as a few extras.

The metal rod came in yesterday and all day I was super excited to get home and finally fix those crappy tie rods. I finally get the workspace all set up and ready to go. Get the rod cut and ball sockets added at the right legth.

Turns out I don't have a nut driver of whatever size the dubro screw/nut is. The cross nut driver that comes with the losi cars had one wrench that was kind of the right size. The problem? I somehow broke the tap off right into the brand new aluminum knuckles I got! I'm so mad and frustrated!

I read that I would have to use the tap to increase the thread size on the corresponding parts of the cars but it was incredibly hard to get that tap in there and once i finally got it to where i thought i was good, it broke off! It was very very tight to turn. Now the tap is stuck inside the threads of the knuckle, pretty much being a waste of 20 bucks for the knuckles and tap on top of the days I had to wait for them to arrive.

Am I doing something wrong or missing some step? Is it supposed to be that hard to get the tap through the aluminum knuckle? I didn't even try with the plastic knuckles I had since the whole point was to get the aluminum ones installed with the dubros.

Here are some pics of my failure. So now I have to replace the useless/broken knuckle with the tap stuck inside as well as the tap itself, correct? How do I keep the next ones from breaking? What size nut driver do I need to get the threaded ball/nut (hehe) installed and tightened down? I'm so frustrated!

One last thing, does anyone know how I can get my microtforums account going? Anyone from here know anyone from there? I see there are recent posts on the site. Are they just not accepting new members or are the mods asleep at the wheel?

Thanks!
Attached Thumbnails Broken Tap/Knuckle trying to install dubros-20160108_013324.jpg   Broken Tap/Knuckle trying to install dubros-20160108_013339.jpg   Broken Tap/Knuckle trying to install dubros-20160108_013413.jpg   Broken Tap/Knuckle trying to install dubros-20160108_013523.jpg  
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Old 01-08-2016, 10:54 AM
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When tapping you need to first make sure you have drilled the hole for the correct size of the threads. Always use a tapping fluid, never dry!
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Old 01-08-2016, 04:29 PM
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Originally Posted by NomadRacer View Post
When tapping you need to first make sure you have drilled the hole for the correct size of the threads. Always use a tapping fluid, never dry!
Yea, I learned that the hard way.

On the RC groups forum I got a reply for some Tap Magic oil.

I also didn't drill out the initial hole larger w/ the appropriate bit (#56=3/64") from what I read. Fail for sure.

Do you have any experience will drilling out the busted tap?

If you don't mind, can you check out the thread I posted in the other boards? I don't mean to link to another board but I've already got some replies and questions there. Maybe you'd be willing to answer them here?

rcgroups - micro section. same thread name.

If not, no worries!

I did find this method online. If you search youtube for this video:
"How to remove a broken tap / drill bit the easy way"

It'll probably strip away the ano but it looks to dissolve the steel inside the aluminum. What do you think? With the Micro-T knuckle being so very small compared to this guys real car part example I would probably only need a very little amount vs what he's using. The knuckle is already pretty much useless if I can't get this tap out. I think trying to drill it out without a press or any real way to stabilize it wont work. Any thoughts?

One more question. Do you think my broken tap is still usable? there are still threads there aside from the jagged edge on the tip where it broke.

I don't have enough posts to provide a working link. My apologizes if this isn't allowed. I'd just like to get as much help as I can and I've already written out a bunch of stuff there.
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Old 01-08-2016, 07:47 PM
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I'm not familiar with any other boards besides this forum (R/C Tech) so can't know where to go.

From your picture it appears (to me) that you may have enough of the broken tap to grab a hold of with a pair of hemostats (serrated jaws). Maybe try to freeze or heat the knuckle and give it a turn?

As to removing the broken tap by a chemical process (nitric acid?), I have no experience with that method.

There are three (3) types of taps...

Taper
Plug
Bottom

Always start with a taper! Flood the part with cutting fluid, turn the tap one turn, then back 1/4 turn. Keep doing it that way till you finish the hole.

I would not try to use a broken tap. It has been stressed and will most likely break off again right away. 0-80 is a very small thread size, delicate to say the least.

I have tapped (internal and external threads) on grade 2 titanium in 2.5mm, 2-56 and larger. If I can be of any help to you, please ask. You can send me a PM if you like.
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Old 01-08-2016, 09:06 PM
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What I'm using is Alum. You can buy it in the spice section at the grocery store. I guess it's used for making pickles or something.

I've just taken some photos and will be uploading them shortly of the how it's going. It seems to be working. There are a bunch of bubbles coming out of the hole where the tap is broken, similar to the videos I watched on youtube of the process. Those guys were dissolving real car bolts that were huge overnight. I figure this little micro tap shouldn't take but a few hours, if that.

With this being a micro t knuckle and me zooming in so close with those photos, there really isn't anything to grab onto to try and twist. I even bought a small engraving bit for my dremel to try and bore it out but ended up not having the right chuck to use it anyway. I didn't even notice that it said not to use on steel. /facepalm.

I bought 3 little containers (overpriced compared to the examples in the vids) of the Alum. I used two in a small pyrex bowl.

It does look like it is fading the anodizing but as long as it's just cosmetic I can replace them later what I figure out how to get these installed cleanly.

I also picked up a tap wrench but I think it's pretty terrible. I tried tightening it around the broken tap just as a fit test but the tap just falls right out. I'm going to see if I can return it tomorrow.

I was able to use the broken tap on the plastic drive/steering bar that the other end of the dubros go into.

Question. I don't have the right size nut driver to tighten the dubro. They have a thin little hex bolt above the threading. Does anyone know what size that is?
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Old 01-08-2016, 09:38 PM
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Default progress shots

Here are some progress shots. The first one is after about 15 mins. The two on the paper towel are after an hour. You can already see through the hole at that point. Just some leftover gunk around the threads to dissolve still!

I have a video I uploaded to my youtube page if anyone is interested. Boards aren't letting me post the link.

Youtube account is mportillo78.
Attached Thumbnails Broken Tap/Knuckle trying to install dubros-20160108_212354.jpg   Broken Tap/Knuckle trying to install dubros-20160108_221835.jpg   Broken Tap/Knuckle trying to install dubros-20160108_221843.jpg  
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Old 01-09-2016, 12:56 AM
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Default It worked!

Some pics of the result. Totally stripped off the ano but that's fine. Small price to pay to be able to recover from that blunder! I'm just glad it worked!

I did make the hole a tad too big on one side of the plastic tie rod. I just super glued the ball screw in for now. I can pull a replacement off my spare micro-t or just upgrade to an aluminum one. I just wanted it back together and working for the weekend.
Attached Thumbnails Broken Tap/Knuckle trying to install dubros-yh7dnsd.jpg   Broken Tap/Knuckle trying to install dubros-klwf2nx.jpg   Broken Tap/Knuckle trying to install dubros-l5w3jgj.jpg   Broken Tap/Knuckle trying to install dubros-1uq8pwa.jpg   Broken Tap/Knuckle trying to install dubros-5ahdmix.jpg  

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Old 01-09-2016, 12:58 AM
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Default the mixture

Last pics here are what the mixture looked like after it cooled off. It crystallized and hardened up.
Attached Thumbnails Broken Tap/Knuckle trying to install dubros-ugbtnx2.jpg   Broken Tap/Knuckle trying to install dubros-k6mfpot.jpg  
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Old 01-09-2016, 05:10 AM
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Glad to know you got it out without much trouble.

For that small of a tap you could just get a good pin vise.
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