Thread: Made a tap

Well done!

Jordan

Great stuff. I have many stihl brushcutters, had a couple of Huskies, and also have a few Shindaiwa's. All have their pros and cons ( I have a weed control and landscaping company)
All have different thread sizes, and a couple both have 10 mm, but different pitches. Very annoying. They charge a fortune for replacement bolts. So if you could make a die, it would be very handy as well. I would be surprised if you could get L.H taps and dies that easily, certainly not cheaply.

Can you tell us how you did it.?

Nice work RC

Must say I'm surprised about your comments about the Stihl stuff. Like you I have a Stihl chainsaw as well as a Stihl brush cutter. Both are the easiest starting pieces of equipment I have ever owned.

Don't ask me about the MTD lawn mower with the B&S engine though

Originally Posted by quercus

Can you tell us how you did it.?

Sure.. I started with a piece of 4140 steel, I centre drill one end and turned it down to 10mm... I then turned the shank down to the thread depth diameter... Then it is time to cut the square on the end of the shank...I used the ER40 dividing chuck to index the tap...

Back into the lathe (have to use 4 jaw chuck or an accurate collet chuck here to get minimal runout) and I them proceeded to cut the thread with the leadscrew running backwards (feeding away from the headstock) As my lathe has an Imperial leadscrew I had to reverse the motor at the end of the cut to get back to the start.. I then turned the top slide round to four degrees and cut a taper on the end although I could have done this before I cut the thread..

Once the thread is cut to size and you have done the taper, back into the collet dividing head and on the mill get an end mill over the centre line of the thread.. I then moved it another 0.5mm to give it a cutting rake...I guessed this figure as I did not feel like doing some geometry at that point in the afternoon..It seems to have have suitable rake.... Index four times cutting as you go..

That's how I did it...It just seemed the logical way to proceed, i have not made a tap before and just mostly did what looked right...

Then off to the belt grinder and I carefully backed off the flutes along the tapered portion only..

If I was going to harden it, I would coat it with soap first as this will stop scale..then heat it with an LPG burner (oxy is way too hot) until it becomes non-magnetic and hold there for a short while then dunk in cold water....Tempering may be required but 4140 does not seem to get that hard and brittle, unlike something like 1045..

Neat job I agree about the Stihl stuff, I had so much trouble with the last Stihl line trimmer I took it to the Stihl agent and told them I no longer wanted it and left it on the counter.

Great work, I'd seen odd size right hand taps made before but never a lefty! Oh yeah, my Dolmar line trimmer starts everytime regardless of what I feed it