LKeithR
Stainless
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- Sep 1, 2011
- Location
- Langley, B.C.
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looking for advice on turning a custom tap
- Thread starter ikoral
- Start date
- Replies 33
- Views 4,249
It looks like you and Rivett608 buy your oversize coins at the same place. Do you have the giant fingers for pictures as well?
implmex
Diamond
- Joined
- Jun 23, 2002
- Location
- Vancouver BC Canada
Hi gbent:
You wrote:
"It looks like you and Rivett608 buy your oversize coins at the same place. Do you have the giant fingers for pictures as well?"
Yeah I do...the increasingly hard thing for me though, is that the microscopes out there are getting blurrier and blurrier.
I don't know why they are doing that to me...it's NOT FAIR!!!
I think it's a conspiracy to shut me up and retire me before I'm ready.
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
You wrote:
"It looks like you and Rivett608 buy your oversize coins at the same place. Do you have the giant fingers for pictures as well?"
Yeah I do...the increasingly hard thing for me though, is that the microscopes out there are getting blurrier and blurrier.
I don't know why they are doing that to me...it's NOT FAIR!!!
I think it's a conspiracy to shut me up and retire me before I'm ready.
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
Last edited:
EmGo
Diamond
- Joined
- Apr 14, 2018
If you had like a little 25 footer, with a Magma grill on the back and a 12 v refrigerator ? Late afternoon run down the hill there, fire her up, head north-east a ways then do a u-turn and back west to Plumper's Cove, park overnight, grill hamburglers or make burritos or catch a few crabs .... back the next day or if it's the weekend, up north a little then down skookumchuck to porpoise bay, nice pizzas, nice people, it's on the way to texada or princess louisa ... leave the boat, take the electric seaplane back to work for a week, repete repete ...
If'n I wuz in your location, it'd be work a week, play a week. Work a week, play a week. There's some pretty fun stuff right out that window .... and more to life than making payments to Haas ...
implmex
Diamond
- Joined
- Jun 23, 2002
- Location
- Vancouver BC Canada
Hi Emanuel:
Sounds like you know my neck of the woods rather well, and yes, it really is God's country.
I'm so very fortunate that my parents decided to emigrate to here from postwar Germany.
In my young years I took pretty good advantage too, skiing, SCUBA diving, hiking, kayaking and sailing Hobie cats.
So I have no regrets.
To your personal fantasy though; when I was in first year dental school (1987) I used my tuition fee money to buy a sailboat...a 21 foot ODay, and man I loved that sailboat.
I had to struggle like Hell to make back the cost and pay my tuition, building injection molds on contract evenings and weekends, but it was bloody well WORTH IT!
In the first years I sailed that damn boat every chance I got, and I loved it.
Ten years later though, I was so ready to get rid of it...the second happiest day during my boat ownership years was when the new bright eyed owner pulled away from the dock and it was back out of my life.
So I hear your fantasy, I had my shot at it, and I'm glad it was so thoroughly enjoyed but I'm also glad it's done.
Great memories, none regretted, but I don't want it anymore...I want other things now.
Haas payments however are not among them...I've got a cute wife, a great life, and my own man cave to play in and pretend I'm doing something useful.
I can still feed my family with dignity...I'm pretty damn lucky.
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
Sounds like you know my neck of the woods rather well, and yes, it really is God's country.
I'm so very fortunate that my parents decided to emigrate to here from postwar Germany.
In my young years I took pretty good advantage too, skiing, SCUBA diving, hiking, kayaking and sailing Hobie cats.
So I have no regrets.
To your personal fantasy though; when I was in first year dental school (1987) I used my tuition fee money to buy a sailboat...a 21 foot ODay, and man I loved that sailboat.
I had to struggle like Hell to make back the cost and pay my tuition, building injection molds on contract evenings and weekends, but it was bloody well WORTH IT!
In the first years I sailed that damn boat every chance I got, and I loved it.
Ten years later though, I was so ready to get rid of it...the second happiest day during my boat ownership years was when the new bright eyed owner pulled away from the dock and it was back out of my life.
So I hear your fantasy, I had my shot at it, and I'm glad it was so thoroughly enjoyed but I'm also glad it's done.
Great memories, none regretted, but I don't want it anymore...I want other things now.
Haas payments however are not among them...I've got a cute wife, a great life, and my own man cave to play in and pretend I'm doing something useful.
I can still feed my family with dignity...I'm pretty damn lucky.
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
J_R_Thiele
Stainless
- Joined
- Jan 22, 2003
- Location
- Columbia Missouri
You have gotten some very good advice, and the responses have been unusually polite.
Actually, they have been too polite.
What you have is closer to a propeller with a a large hub. .2" of blades driven by a .36" hub. It will work in air or water (liquids) but not work well in metal.
You need to redesign the thread form to something more conventional. Why do conventional threads have the form they do? Because in the early days EVERYONE made their own taps, and if it was too hard to make- or use- they tried something else. What we now see as "conventional" were the winners in this evolutionary process.
I am not saying its impossible to make the tap. Make enough of them, get good enough at removing the broken ones, and eventually you will end up with a tapped hole.
OK, I have to ask. What is going to thread into this hole? There must be a reason for what you want.
I guess by the time you can make the tap you will be able to make the screw or shaft or whatever.
If you HAVE to use that thread form I would look at making something like a speed nut Speed nut - Wikipedia. The easy way would be to take .050 thick aluminum and make a form punch that cuts out the center, puts in a cut for the thread crest and forges the thread flanks.
The next step is to figure out how to attach one or more to your aluminum plate.
Actually, they have been too polite.
What you have is closer to a propeller with a a large hub. .2" of blades driven by a .36" hub. It will work in air or water (liquids) but not work well in metal.
You need to redesign the thread form to something more conventional. Why do conventional threads have the form they do? Because in the early days EVERYONE made their own taps, and if it was too hard to make- or use- they tried something else. What we now see as "conventional" were the winners in this evolutionary process.
I am not saying its impossible to make the tap. Make enough of them, get good enough at removing the broken ones, and eventually you will end up with a tapped hole.
OK, I have to ask. What is going to thread into this hole? There must be a reason for what you want.
I guess by the time you can make the tap you will be able to make the screw or shaft or whatever.
If you HAVE to use that thread form I would look at making something like a speed nut Speed nut - Wikipedia. The easy way would be to take .050 thick aluminum and make a form punch that cuts out the center, puts in a cut for the thread crest and forges the thread flanks.
The next step is to figure out how to attach one or more to your aluminum plate.
Last edited:
Thanks for the additional suggestions. I am happy to say that I was mistaken in my original post and I actually need to tap either 360 brass or UHMWPE.
I need the tap/taps ( I do plan on making serial taps) to repair several valves. The thread is a proprietary thread that is used on more then one model of valve that I need to repair. We have ordered replacement nuts in the past but both of the shops that we had make the parts are out of bushiness and that was before I started working here about 11 years ago.
A quick nut would not work in this case since the nut I'm tapping is screwed onto the face plate and is what primarily supports the shafts weight as well as the bellows that is pressfit to it.
All I have at the moment is W1 so I decided to try one more time with that for the sake of testing out peoples suggestions. I started with about 25% less stickout and the 60 degree tool with a increased relief angle and I got better results but started running into issues at about 0.050" depth again so I started cutting using the "wiggle-wagging" approach. By making it so only one side was cutting at a time I was cutting drastically better with little to no chatter. I got as deep as I could with the 60 degree then swapped to the 32 degree form. Things started out fine but by the time I got to the point where I was cutting with the full 0.040 nose things became terrible again. Even if I was cutting one side and not the other I was still having issues. So I decided to ground my nose to a point and get to just shy of full depth using a sharp nosed 32 degree form. Once the nose was gone the cuts where clean again. I made it all the way to the depth I wanted with no issues at all.
I found that if I made several passes in the middle I could get a half decent finish even with my sharp nosed tool. So I decided not to reground the flat onto the nose and give the tap a shot with the rough minor diameter. I have added the flutes and taper but I still need to file in the relief and harden it before testing.
If the fit is too bad I'll try again with the nose flat added (and if I have too much trouble swap to O1) but for this job I think the finish I have will be adequate.
I need the tap/taps ( I do plan on making serial taps) to repair several valves. The thread is a proprietary thread that is used on more then one model of valve that I need to repair. We have ordered replacement nuts in the past but both of the shops that we had make the parts are out of bushiness and that was before I started working here about 11 years ago.
A quick nut would not work in this case since the nut I'm tapping is screwed onto the face plate and is what primarily supports the shafts weight as well as the bellows that is pressfit to it.
All I have at the moment is W1 so I decided to try one more time with that for the sake of testing out peoples suggestions. I started with about 25% less stickout and the 60 degree tool with a increased relief angle and I got better results but started running into issues at about 0.050" depth again so I started cutting using the "wiggle-wagging" approach. By making it so only one side was cutting at a time I was cutting drastically better with little to no chatter. I got as deep as I could with the 60 degree then swapped to the 32 degree form. Things started out fine but by the time I got to the point where I was cutting with the full 0.040 nose things became terrible again. Even if I was cutting one side and not the other I was still having issues. So I decided to ground my nose to a point and get to just shy of full depth using a sharp nosed 32 degree form. Once the nose was gone the cuts where clean again. I made it all the way to the depth I wanted with no issues at all.
I found that if I made several passes in the middle I could get a half decent finish even with my sharp nosed tool. So I decided not to reground the flat onto the nose and give the tap a shot with the rough minor diameter. I have added the flutes and taper but I still need to file in the relief and harden it before testing.
If the fit is too bad I'll try again with the nose flat added (and if I have too much trouble swap to O1) but for this job I think the finish I have will be adequate.
implmex
Diamond
- Joined
- Jun 23, 2002
- Location
- Vancouver BC Canada
Hi again ikoral:
There are a few things you can do to make your job easier, and some of those you have already discovered.
A key one is to reduce the amount that is cut in one pass, and the length of engagement of the cutting edge is at least as important as the depth of cut as you've been finding out.
There are some tactics you can use to help you.
One important thing is the amount of rake on the cutting edge.
If you make the threading tool with only a very tiny flat on the end and then grind a little ditch all the way around the edge of your threading tool (kind of like the shape on the top of a standard carbide turning insert), you can have positive rake all around the periphery of the cutting edge while keeping the entire edge on a single horizontal plane that intersects the axis of the workpiece, and you'll find it cuts much more freely and makes a much nicer thread while using much less force to peel off a chip.
A second very useful thing you can do, is set the compound slide to zero (parallel to the axis of the lathe spindle.
Now you can rough the thread by driving in a bit with the cross slide, then driving incrementally across the width of the thread gullet in small bites until you get to the other side of the gullet, then go back to the trailing flank, dropping in a bit deeper, and going across the gullet in small increments again.
So the tool never takes a wide bite during the roughing.
It's how really big threads have to be cut because the lathe is typically not powerful enough to take a full width bite and you can't make a tool strong enough to take the force.
Once the thread is roughed to full depth, you can reset the compound to the trailing flank angle and walk incrementally down the trailing flank face until you get to the thread root.
Then you reset the compound to the leading flank angle and walk down it too, also in small increments.
So both flanks are generated rather than how threads are typically cut where the leading flank is formed and only the trailing flank is generated.
A form cut by definition is one where the full width of the tool is engaged...you don't want to do that.
This is a tedious way to cut threads but it is very safe because the tool is never forced to take a big bite.
Here are two pictures of buttress threads cut this way.
My apologies to those who have seen these pictures before...I've shown them a few times on PM now, but it shows what you can cut with this technique, and it's relevant to the OP's problem.
A second thing to consider:
Since you have W-1 in stock and no O-1 you may choose to oil quench it rather than water quench it.
It won't get as hard, but it won't get as brittle either.
Draw it back 3 times and when you draw it back (temper it) don't quench it...sneak up very slowly until the colours just begin to run and then let it cool in still air.
Do that three times, polishing it perfectly between draws and DON'T TOUCH IT after polishing it .
The oils in your skin will booger the colours you use to judge the draw.
Alternatively (and far better IMO) borrow your wife's kitchen oven and temper it in there so you can control the temperature.
That way you have the best chance of getting it as tough as you can while still preserving the hardness.
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
There are a few things you can do to make your job easier, and some of those you have already discovered.
A key one is to reduce the amount that is cut in one pass, and the length of engagement of the cutting edge is at least as important as the depth of cut as you've been finding out.
There are some tactics you can use to help you.
One important thing is the amount of rake on the cutting edge.
If you make the threading tool with only a very tiny flat on the end and then grind a little ditch all the way around the edge of your threading tool (kind of like the shape on the top of a standard carbide turning insert), you can have positive rake all around the periphery of the cutting edge while keeping the entire edge on a single horizontal plane that intersects the axis of the workpiece, and you'll find it cuts much more freely and makes a much nicer thread while using much less force to peel off a chip.
A second very useful thing you can do, is set the compound slide to zero (parallel to the axis of the lathe spindle.
Now you can rough the thread by driving in a bit with the cross slide, then driving incrementally across the width of the thread gullet in small bites until you get to the other side of the gullet, then go back to the trailing flank, dropping in a bit deeper, and going across the gullet in small increments again.
So the tool never takes a wide bite during the roughing.
It's how really big threads have to be cut because the lathe is typically not powerful enough to take a full width bite and you can't make a tool strong enough to take the force.
Once the thread is roughed to full depth, you can reset the compound to the trailing flank angle and walk incrementally down the trailing flank face until you get to the thread root.
Then you reset the compound to the leading flank angle and walk down it too, also in small increments.
So both flanks are generated rather than how threads are typically cut where the leading flank is formed and only the trailing flank is generated.
A form cut by definition is one where the full width of the tool is engaged...you don't want to do that.
This is a tedious way to cut threads but it is very safe because the tool is never forced to take a big bite.
Here are two pictures of buttress threads cut this way.
My apologies to those who have seen these pictures before...I've shown them a few times on PM now, but it shows what you can cut with this technique, and it's relevant to the OP's problem.
A second thing to consider:
Since you have W-1 in stock and no O-1 you may choose to oil quench it rather than water quench it.
It won't get as hard, but it won't get as brittle either.
Draw it back 3 times and when you draw it back (temper it) don't quench it...sneak up very slowly until the colours just begin to run and then let it cool in still air.
Do that three times, polishing it perfectly between draws and DON'T TOUCH IT after polishing it .
The oils in your skin will booger the colours you use to judge the draw.
Alternatively (and far better IMO) borrow your wife's kitchen oven and temper it in there so you can control the temperature.
That way you have the best chance of getting it as tough as you can while still preserving the hardness.
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
Attachments
J_R_Thiele
Stainless
- Joined
- Jan 22, 2003
- Location
- Columbia Missouri
Proprietary explains a lot. They succeeded in making it unusual.
Good to hear of your progress.
You have not mentioned if you are using a center or not. They can be very helpful- but can also get in the way with smaller work. Because you have one end of the work in a collet, the end in the center does not have to be under much pressure. I would think about putting a 60* taper on the end of the tap and making my own female dead center for the tailstock.
You have not mentioned what you are using for a cutting fluid. Moly-Dee is messy and makes it hard to see what is going on- but it is great at reducing friction and edge build up.
Good to hear of your progress.
You have not mentioned if you are using a center or not. They can be very helpful- but can also get in the way with smaller work. Because you have one end of the work in a collet, the end in the center does not have to be under much pressure. I would think about putting a 60* taper on the end of the tap and making my own female dead center for the tailstock.
You have not mentioned what you are using for a cutting fluid. Moly-Dee is messy and makes it hard to see what is going on- but it is great at reducing friction and edge build up.
I did note in my OP that I have been using a live center for support, it is a tight fit but it works.
I am using " LPS tapmatic natural cutting fluid" There are tight restrictions on cutting fluid here so I don't have any options on that front.
Thanks again to everyone for the help. I had to put this on a back burner for a while but I was now able to come back and have something that works.
I tried making serial taps first but I could not get the taps to start successfully. With how large and course the threads where I would wallow out the hole before the teeth could engage well
.
I do have a 3 axis micro mill that is usually used for machining rare metal braze foil. So to give the tap something to bite into I made a thread mill with the 32 degree angle that I could use with the 3 axis mill to rough cut the thread.
The thread mill worked well enough that I ended up using the thread mill to cut the threads all the way to about 0.010" shy of the final major diameter. I then ran my final tap through to get a cleaner finish and have nuts that fit rather nicely.
I tried making serial taps first but I could not get the taps to start successfully. With how large and course the threads where I would wallow out the hole before the teeth could engage well
.
I do have a 3 axis micro mill that is usually used for machining rare metal braze foil. So to give the tap something to bite into I made a thread mill with the 32 degree angle that I could use with the 3 axis mill to rough cut the thread.
The thread mill worked well enough that I ended up using the thread mill to cut the threads all the way to about 0.010" shy of the final major diameter. I then ran my final tap through to get a cleaner finish and have nuts that fit rather nicely.
implmex
Diamond
- Joined
- Jun 23, 2002
- Location
- Vancouver BC Canada
Good morning ikoral:
That is terrific; you've done a very nice looking and difficult job and can be justifiably proud of your work.
Pat yourself on the back for persistence and ingenuity, and stick out your tits a bit
to your co-workers...you deserve to swagger (but not TOO much)
On another note...I presumed that you were an inexperienced hobbyist with relatively limited skills, and the tone of some of my posts reflected that presumption.
I can see from what you've created that I misjudged your skill set.
My apologies if I sounded like I was talking to a beginner.
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
That is terrific; you've done a very nice looking and difficult job and can be justifiably proud of your work.
Pat yourself on the back for persistence and ingenuity, and stick out your tits a bit
to your co-workers...you deserve to swagger (but not TOO much)On another note...I presumed that you were an inexperienced hobbyist with relatively limited skills, and the tone of some of my posts reflected that presumption.
I can see from what you've created that I misjudged your skill set.
My apologies if I sounded like I was talking to a beginner.
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
