# Eagle



## fltenwheeler (Aug 3, 2022)

I decided to work on my Bob Shore Eagle for once. I have a very early kit and the drawings had some major issues. I scraped one base casting due to a broken tap. Then the hole layout for the gears were to tight. But I am still moving on with it.


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## stevehuckss396 (Aug 3, 2022)

Well I hope things go well for you.  Having bad drawings can really complicate things and suck the fun right out of the build.


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## fltenwheeler (Aug 6, 2022)

For once I was able to silver solder parts without make a mess of too much solder. This is part of the governor with 1/2” brass balls. 

Tim


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## william_b_noble (Aug 7, 2022)

you have a chance of getting a broken tap in aluminum out three ways:
1. alum
2. heat to 400 or so deg and use a tap extractor - the aluminum will expand a lot more than the steel
3. diamond drill point and a high speed drill (dremel, etc) with lots of water for lubriction - just cut the flutes of the tap - it's tedious but it works.  I use a 200,000 RPM dental type drill


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## Steamchick (Aug 7, 2022)

I have heard that watchmakers make an arc erosion tool to erode tiny taps that have broken in the workpiece. Slow but "clean" for eroding the core of the tap without damaging the thread. The flutes can then be fiddled out.








						Electro Arc
					

We are part of a family of businesses providing unique products that improve product quality, reduce costs and eliminate scrap. Our production and distribution facilities are located in North America and United Kingdom, easily providing machines, accessories and supplies to clients worldwide.




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K2


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## william_b_noble (Aug 7, 2022)

EDM has been around for 50 0r 60 years. If the tap is 000 or something, the a diamond point is tough, but if it is 4 or larger, you can use diamond just fine.  If you have a mill, you can generally use a carbide drill too.  I had forgotten that in my prior post.   But heat and a tap remover is easiest, try it.  Tweezers might work, or long nose pliers if you don't have, or can't get a tap remover, but heat is imperative


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## Steamchick (Aug 7, 2022)

I have fiddled out broken taps with fine circlip pliers (smaller than my electrical snipe nosed pliers), but haven't broken bigger taps to have needed to drill them out. I agree that cooking hot helps remove bits from aluminium  - But how hot? I use a wipe with a bar of soap, then when it turns black, the aluminium is hot. Any other ideas?
K2


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## william_b_noble (Aug 7, 2022)

Steamchick said:


> I have fiddled out broken taps with fine circlip pliers (smaller than my electrical snipe nosed pliers), but haven't broken bigger taps to have needed to drill them out. I agree that cooking hot helps remove bits from aluminium  - But how hot? I use a wipe with a bar of soap, then when it turns black, the aluminium is hot. Any other ideas?
> K2


I just put a heat gun on the aluminum and when it is too hot to touch, proceed.  you can use a thermometer if you prefer.


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## karlw144 (Aug 7, 2022)

Had problems with the drawings too. This is an early run, got it slowed down after some fiddling. Just can’t find the vid. 
Karl


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## fltenwheeler (Aug 7, 2022)

I will get it running one of these days. This one was marked serial number 41. 

I am glad to see yours running. It gives me hope. 

Tim


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## arnie (Aug 7, 2022)

There is a chemical that attacks hard steel and not aluminum, I can't remember what it's called but I'm sure a little research can be done. It's a simple chemical you could buy at a hobby shop or big toy store.


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## L98fiero (Aug 7, 2022)

arnie said:


> There is a chemical that attacks hard steel and not aluminum, I can't remember what it's called but I'm sure a little research can be done. It's a simple chemical you could buy at a hobby shop or big toy store.


It's called Alum and it's usually in the canning and spice section of grocery stores. If you have a stainless steel container place the part in a solution of water and alum and heat to boiling, it takes time but the tap will just fall out.


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## william_b_noble (Aug 7, 2022)

Yes, alum was my number 1 item in the list upthtead.  Maybe I was too terse?


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## Claireb (Aug 8, 2022)

william_b_noble said:


> you have a chance of getting a broken tap in aluminum out three ways:
> 1. alum
> 2. heat to 400 or so deg and use a tap extractor - the aluminum will expand a lot more than the steel
> 3. diamond drill point and a high speed drill (dremel, etc) with lots of water for lubriction - just cut the flutes of the tap - it's tedious but it works.  I use a 200,000 RPM dental type drill


Hi I'm new to site.
I'm trying to sell some books.
Elmers engines etc,could you please point me in the right direction


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## fltenwheeler (Aug 8, 2022)

I tried Alum. It attacked the alloy the main casting was made from.  I purchased a new casting and machined it to the original print. The gear spacing was too close. I ended up lapping them in. The other major problem was the head was drawn backwards. So I ended up making two of them also.  

Tim


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## cds4byu (Aug 8, 2022)

You can also use nitric acid to remove taps from aluminum.


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## Bentwings (Aug 8, 2022)

william_b_noble said:


> you have a chance of getting a broken tap in aluminum out three ways:
> 1. alum
> 2. heat to 400 or so deg and use a tap extractor - the aluminum will expand a lot more than the steel
> 3. diamond drill point and a high speed drill (dremel, etc) with lots of water for lubriction - just cut the flutes of the tap - it's tedious but it works.  I use a 200,000 RPM dental type drill.  I don’t remember the exact expansion ratio but about 4 times at least the steel tap will not expand much most home shops could not measure this .


I like the heat you can bleed a little never seize in at the  same time 

Also I like left hand drills removing a broken 2-56 tap or 2mm tap is tricky as it is if you have a late you might get away carefully measure location and drill from the back side a blind hole is very hard  I worked in a primitive by today standards EDM room we had titanium air craft parts with multiple 2.56 and 2 mm taps broken. Heat is not very good here but we used very thing copper wire and carefully made copper tungsten “ heavy metal” electrodes  it was a very PIA project . I would have not felt good being responsible for this machining error. I don’t remember what the company charged but it was very significant 20 to 30 broken taps per part . Must have been runaway cnc machine . 


Today I drilled a dozen # 10 brass nuts to 1/4-40 ME tap drill size now I’m tapping them   Very carefully I can use the cordless drill to run the tap in while normally bass doesn’t need lube I use a drop of tapmatigic . It seems to help although the tap is high quality so it cuts very cleanly.   Ultimately I’ll sand or lap them equal and flat  for use as precision spacers . I have quite a number of copper washers with just 6mm hole all are within .0005 thickness best as my “ very near calipers can measure .


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## ChazzC (Aug 9, 2022)

cds4byu said:


> You can also use nitric acid to remove taps from aluminum.


Yes, Guy Lautard recommends "pure" Nitric Acid in _The Machinist's *Third* Bedside Reader._ He also points to Brownell's _Gunsmith Kinks V.1_, which also recommends Nitric Acid as well as trying solid Carbide drills.


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## Chris Murphy (Aug 10, 2022)

Nitric acid works quite well-as I can personally testify-BUT (and it is a big BUT)-whilst it does not attack aluminium-it DOES attack other metals-and since very few people are tapping pure aluminium-in practice we are using a variety of aluminium alloys, the acid approach can lead to discolouration due to the trace components of the alloy reacting with the nitric acid. In some cases this may not matter-in other cases it may. In my case I ended up with a discoloured engine pan-(sandcast , low Si alloy-ended up mottled black and grainy) - which didn't trouble me especially, but for some components which might need to have cosmetic appeal -shiny, polished or anodised-you might run into issues.

ChrisM


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## timo_gross (Aug 10, 2022)

william_b_noble said:


> you have a chance of getting a broken tap in aluminum out three ways:
> 1. alum
> 2. heat to 400 or so deg and use a tap extractor - the aluminum will expand a lot more than the steel
> 3. diamond drill point and a high speed drill (dremel, etc) with lots of water for lubriction - just cut the flutes of the tap - it's tedious but it works.  I use a 200,000 RPM dental type drill


4. I give it to the neighbour and he does his magic (spark errosion).
5. Use a small Endmill and mill around the tap (worked once for me) or one of those drills that leave a core. Later plug oversize hole and redrill.


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## clockworkcheval (Aug 10, 2022)

By far the best way to remove difficult-to-reach broken taps is EDM. In a few cases I ask a friend of mine with acces to a wide selection of EDM equipment to do this. However I first try to use a HM drill. As most taps are HSS a HM drill will cut them up. As a regular full HM drill is rather costly I take a cheap stone-drill which has an HM bit at the top and I regrind it to cut HSS. This works quite often.
Another application for reground stone-drills is piercing the sometimes quite hard skin of castings.


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## Bentwings (Aug 10, 2022)

ChazzC said:


> Yes, Guy Lautard recommends "pure" Nitric Acid in _The Machinist's *Third* Bedside Reader._ He also points to Brownell's _Gunsmith Kinks V.1_, which also recommends Nitric Acid as well as trying solid Carbide drills.


I don’t know about the nitric acid I’d guess it quickly corpses the seized area thus weakening it . Sounds like ifvyhe tap gets stuck that would bevthevtimevto apply it don’t keep turning until the tap breakes


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## clockworkcheval (Aug 10, 2022)

When a tap breaks in a not-too-big or complex workpiece of steel I simply throw the thing in the wood stove that heats my workshop. Next morning I can almost always get the broken tap out with a regular HSS drill.


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## L98fiero (Aug 10, 2022)

clockworkcheval said:


> When a tap breaks in a not-too-big or complex workpiece of steel I simply throw the thing in the wood stove that heats my workshop. Next morning I can almost always get the broken tap out with a regular HSS drill.


What kind of taps are you using, M2 tool steels(1.3343) are annealed at approx 885°C (1625°F) and cooled at 72°C (162°F) per hour to 900°F


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## dazz (Aug 11, 2022)

Chris Murphy said:


> Nitric acid works quite well-as I can personally testify-BUT (and it is a big BUT)-whilst it does not attack aluminium-it DOES attack other metals-and since very few people are tapping pure aluminium-in practice we are using a variety of aluminium alloys, the acid approach can lead to discolouration due to the trace components of the alloy reacting with the nitric acid. In some cases this may not matter-in other cases it may. In my case I ended up with a discoloured engine pan-(sandcast , low Si alloy-ended up mottled black and grainy) - which didn't trouble me especially, but for some components which might need to have cosmetic appeal -shiny, polished or anodised-you might run into issues.
> 
> ChrisM


I have also used Nitric acid but with all the problems above. Also Nitric acid is very dangerous.  Take a lot of care if using it.


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## clockworkcheval (Aug 11, 2022)

The taps I'm using are Völkel hand-taps Made in Germany from HSS-E (with some Cobalt). Every once in a while I throw a piece of Aluminium in my wood stove which comes out melted. So the temperature in the wood stove is higher than say 700 degrees Celsius. This ain't 885 degrees Celsius, but apparently staying in there for about 12 hours and cooling extremely slow in the cooling ashes seems to soften the tap enough.


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## L98fiero (Aug 11, 2022)

clockworkcheval said:


> The taps I'm using are Völkel hand-taps Made in Germany from HSS-E (with some Cobalt). Every once in a while I throw a piece of Aluminium in my wood stove which comes out melted. So the temperature in the wood stove is higher than say 700 degrees Celsius. This ain't 885 degrees Celsius, but apparently staying in there for about 12 hours and cooling extremely slow in the cooling ashes seems to soften the tap enough.


Wow, I didn't think a stove would get that hot!


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## awake (Aug 11, 2022)

clockworkcheval said:


> The taps I'm using are Völkel hand-taps Made in Germany from HSS-E (with some Cobalt). Every once in a while I throw a piece of Aluminium in my wood stove which comes out melted. So the temperature in the wood stove is higher than say 700 degrees Celsius. This ain't 885 degrees Celsius, but apparently staying in there for about 12 hours and cooling extremely slow in the cooling ashes seems to soften the tap enough.


I think I may have done something similar before - melted the part away from the offending broken tap. Problem solved, tap removed ... lump of aluminum returned to the scrap bucket!


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## integerspin (Aug 11, 2022)

Battery acid[sulphuric acid] and a battery charger.


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## Sprocket (Aug 11, 2022)

I can't find a picture right now, but in aluminum, I have put a nut over the end of the broken tap then welded through the hole. I guess the combination of heat and something to hold onto works, because they turn out with the nut. It has to be close to the workpiece surface or above.
Doug


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