Edwards Radial 5 build thread --- PHOTOS!

JRaut said:
Well, I'm working on the heads and broke a 4-40 tap. This is reminiscent of one of my very first posts on this thread re: the crankcase.

It was a carless mistake that shouldn't have happened. I was in a rush trying to finish up tapping the thread before heading upstairs for dinner. I've already learned that lesson more than once before. Oh well.

Unfortunate, but not the end of the world.

I ordered several 2mm solid carbide flat-bottom end mills, which are slightly smaller than the tap drill size of a 4-40 thread. I've had very good luck drilling out broken taps with carbide end mills. Crossing my fingers it goes smoothly here, as I've probably got 5 hours into each of the heads so far.

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I've had REALLY good luck with the Walton Tap Extractors as a first step before going to endmills. They DO go as low as #4, though I've never tried going that low (I think I did a #10 once?). They DO require it be a 3 flute that small I think though: https://www.amazon.com/Walton-10043-Flute-Extractor-Square/dp/B0006N8DDM
 
Thanks for the tip @ErichKeane.

I'll give the carbide end mills a try first, as I've already ordered them. Should arrive in the next few days. Only cost me about $19 for a set of 5 made in Canadia.

But that's good to know the Walton's actually work. I've seen them many times over the years, but always thought they were more of a gimmick than anything else. And they ain't cheap, particularly if you buy a whole kit.
 
JRaut said:
Thanks for the tip @ErichKeane.

I'll give the carbide end mills a try first, as I've already ordered them. Should arrive in the next few days. Only cost me about $19 for a set of 5 made in Canadia.

But that's good to know the Walton's actually work. I've seen them many times over the years, but always thought they were more of a gimmick than anything else. And they ain't cheap, particularly if you buy a whole kit.
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Using the carbide might mean you don't have enough meat to use the Waltons anymore. They NEED to have the clamp as close to the break as possible, otherwise they just bend the fingers.

I'll note that I've never successfully removed a tap with a carbide endmill before. If it is an HSS tap(as I often end up with), Carbide seems to HATE cutting HSS, and just sort of mangles stuff. I have also had carbide endmills 'walk' enough to ruin the sidewall of the part the handful of times it has made ANY amount of cut.
 
I'd recommend trying the least destructive first.
walton extractor.
ALUM.. since you have aluminum heads you can mix up alum in water and soak the head.. it will eat the tap out in (edit) in a few minutes to a day. depending on the strength of the solution.
Look it up.
 
While I do appreciate the suggestions, I intend to go forward with the carbide end mill plan.

I've already purchased the end mills and have had good luck with that method in the past. The Walton would be another ~$20 and an extra few days wait. I'll try the Walton method in the future if I come across a bargain on a set of them.

I've tried the Alum method --> HERE <-- and had zero success. In fact, it ruined my part. I will never be trying the Alum method again.
 
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odd, can I ask was your part made of Aluminum? the part must be non-ferrous, because it eats ferrous metals.

just want to understand what happened.
 
I'm really not sure what went wrong. The part was indeed aluminum (6061 or 7075, can't remember off the top of my head). And the tap was indeed HSS.

I let the part sit in a warm/hot alum/water bath for a day or two. I initially saw some bubbles, suggesting that the tap was being eaten away, but by the time I took the part out it had a nasty scale all over it and the tap was still very much intact. Instead of trying to remove all the scaling (and still having to figure out a way to get the tap out), I just started the part over again.

I don't think the part got eaten away, but the nasty scale would have been a big pain to remove.
 
Well, I was able to drill out the #4-40 tap that I broke off in one of the heads.

I used a 2mm solid carbide end mill to do so. Actually, I used two. One broke in the process, but I ordered a 5-pack expecting to break more than just one. So I'd call that a raving success!

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In other news, I'm making some really good progress on the heads. Here are a couple teaser photos to whet your appetite. A full write-up on making the heads will still be a week or two out, as there are quite a few steps required to make each of them.

Bottle cap for scale.

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