Gallery, Projects and General > Project Logs
a nine cylinder radial engine, plans by "ageless engines"
madjackghengis:
Ahhhh!! the secret weapon! I've read many stories and many laments over the years, about the difficulty of getting the tappings out of small holes, as they tend to clog the flutes and can cause tap breakage. I put a coupling on a small grease gun, tapped out to take the "needle" that comes with a air blow gun set, and I inject each hole full of grease before tapping. As you tap, the tap entering, pushes the grease and cuttings up the flutes and out, at the same time lubricating the tap.
Having just spent two and a half days tapping out some hundred and sixty or seventy #4-40 holes, I figured I needed a secret weapon, and it worked as planned, but I also learned considerable about small hole tapping. Of the six taps I broke so far, one was broken because I bottomed it out, four were broken because they were started less than straight, and one was broken by side force used in attempting to straighten out the start with too much force.
If you ream a good clean countersink after drilling, larger than the diameter of the tap, use a piece of steel with a guide hole drilled to start it straight, hold the tap holder between the thumb and forefinger, as close to the tap centered as possible. Pressing down on the tap, with feel, get all the flutes touching, by feel, start the tap, with slight pressure, but focus on keeping the flutes feeling even in their bite. Once you've got a full half turn that feels like the first thread has a full bite, continue to turn the tap while pulling up on the tap holder gently, this lets the tap absolutely follow the lead of the tap in the hole that exists, and allows it to ignore pressure in the wrong directions. Once you have two full threads started by pulling up, you will find that you just have to move your finger and thumb out a little at a time to gine the leverage necessary, to tap straiught in. If you do not hit a strong moment of opposition, tap straight through to the end. Otherwise, back off when it gets tough, enough to break the chips.
Mad Jack
madjackghengis:
First, for Crankshafter, a stove, because when you live in Norway, you need one for your shop. This one is made from a three hundred gallon propane tank and heats my forty by sixty foot shop well.
a photo of two broken taps
another view
the third broken tap
drilling down to get the last of the last broken tap
with the last of the tap removed, the whiole is welded up to be re-machined
ieezitin:
Jack.
I must say that’s a unique way of tapping small bore threads, I read your post with utmost intensity, I too do a lot of small bore tapping I will give your experience of this way of tapping a trial. Thank you for your detailed explanation..
All the best. Anthony
Darren:
Not to distract from your excellent engine build, and welding rescue work :clap:
I do like your heater :)
crankshafter:
Hi madjack.
Wish I have space for such neat "little" stove. :bugeye: But now I do know where the the Global Warming started :bugeye: :bugeye:
BTW: Jack thanks for showing how you "secret weapon" works. :clap: :clap: Def. will try it out.
Crankshafter.
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