Metal Lathe for Multi-start threads

[lign]

Hi All,
So, 7 years have passed since I logged in last. I bought a Micro-Mark 7x16 lathe specifically for making multi-start threads and realized later that 12 TPI is too fine. I made some pretty impressive segmented pens (if I do say so myself) but stopped making pens due to raising a family and frustrations with kit components. Now I'd like to get back into this.

Can anyone tell me if they have successfully used a small lathe (9x19, 10x22, etc) for cutting multi-start threads for kitless pens? I found a nice discussion of it on Silver Hand studio's site suggesting that 8TPI is acceptable but seeming to also suggest that reverse is necessary.

Any advice is greatly appreciated!

 

[randyrls]

I checked my normal carry pen and it has normal right hand threads. That is a sample of only one though. I have not made any pen sections, Sorry.

 

[More4dan]

I've been turning on a 7 x 10 mini metal lathe for about 2 years now. For my early kitless pens, I cut the outer threads with the lathe and used the lathe to make my own taps for the inner threads. What a pain it was. I learned a lot. Mostly what I learned was I got better results with using taps and dies with guides that mount in the tailstock. It is also much quicker. For double threads you will have to find a way to advance the compound slide and retract the cross slide both to start in the correct place for the second set of threads. Or you could leave the slides alone and figure out how to turn your material 180 degrees w/o moving it into the chuck. You could mark the material at one jaw of the chuck and readjust to the mark for each jaw moving it 120 degrees for a triple thread. You would cut the same thread 3 times but just move the material. It wouldn't take me many times messing up my blanks before I got into the next group buy for a set of taps and dies. PM me if you have questions, I'll send you my cell number.

Danny


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[PatrickR]

I cant help with this but there is a maker on here (forget who) that makes a modified acme thread that is very cool. It by passes some of the problems associated with triple starts.
Here's a pic i saved.

 

[magpens]

The maker referred to by Patrick is jalbert.

In doing triple start on a lathe, I think you have significant challenges. . I believe there have been threads here about doing that; could be the same maker, or perhaps skiprat.

I cannot see how reverse would make things any easier.

 

[lorbay]

Here is the link to Skip-Rats triple start threading.
http://content.penturners.org/library/techniques/skiprats_triple_start_threading.pdf

Lin

 

[bmachin]

Dave,

Some perspective:

Using 12 tpi gearing is going to give you a fine 36 tpi triple triple start.That is pretty fine, but I know at least one pen maker who uses it.

Since most of us tend to think metric, the two most common triple start tap/die pitches that are ordered are .75 and .8 mm if I'm not mistaken. A 0.8mm pitch translates into 31.8tpi. So if you set up your change gears for either 10 or 11 tpi you will be right in the ballpark (i.e. 30 or 33). If you have a 21 tooth gear you can set up for almost exactly 0.8mm.

24 tpi is a little bit coarse. What happens when you set up the Sieg 7X lathes for 8tpi is, due to the fact that you are driving the carriage a long distance (1/8 inch or 2 turns of the leadscrew) for each turn of the spindle, it tends to kick out of gear when driven forward. If you turn the spindle in reverse and cut the thread with the tool inverted, this will not happen. Another work-around is to drive the system by turning the leadscrew rather than the spindle.

Triple start threading isn't hard. It's slower than taps and dies, but it frees you from being locked in to specific diameters. Like anything else its a matter of practice, and well worth learning, even if you eventually buy the tap and die sets. Believe me, you won't want to use that $100 die set on a Damascus blank.

Take a look at Skiprat's tutorial for sure.

Hope this helps.

Bill

 

[magpens]

Gee ... thanks, Bill ... that is very illuminating !

I would never have dreamed about the reverse trick ... as you may have read above, I did not know this.

I do have a 7x lathe so someday I might have to use this trick.

 

[lign]

Thanks so much for the helpful replies so far! To be honest, sometimes my hobbies are just excuses to buy really cool tools. I'm debating the possibility of getting a bigger lathe that can do 8 TPI. I am reluctant to be stuck with the size of a tap and die. When I spend 30 to 40 hours on a single pen, I HATE HATE HATE when my equipment ruins it. That's why I sold my Grizzly drill press and bought a Jet 17" drill press with laser. That's also why I sold my Grizzly lathe and bought a Powermatic. (BTW, I have other Grizzly tools I love and I don't hate Grizzly).

The picture attached is one of the last pens I made years ago. The scallops are sterling silver and jade and the body is ebony and Mother-Of-Pearl acrylic. I made it a heptagon (7-sides) because the guy I made it for wanted no doubt that it was one-of-a-kind.

When I spend this kind of time to make a pen, I don't want to be limited by anything, including sizes or crappy components. I'm a true pen lover (I own Pelikans, Parkers, and etc that cost me a fortune). I quit making pens because I was just so frustrated. I never made pens that truly measured up to the works of art I wanted to make.

Rant over. :befuddled:

I did read Skiprat's awesome material, and I realize that if I do this, I'll have a big learning curve.

I'm considering a number of options, all the way from Grizzly's variable speed 8x16 to their monster combo mill/lathe that can cut 4 TPI and costs $2,350. Any thoughts?

 

[magpens]

Dave, that is one beautiful pen !!!! . I am certainly glad you decided to rejoin us.

 

[bmachin]

Dave,

Your MicroMark will certainly do the job and do it well. Of course if you want a bigger lathe, have at it. We all want one!

There are makers here who do all of their threading on 7x Sieg lathes.

The Sieg lathes can be frustrating at times. Mine recently just locked up on me from debris in the leadscrew bearings. A little minor disassembly cleaning and lubrication can go a long way. Lesson learned!

There are a lot of tweaks out there to make the 7x's much more precise if you like fooling around with your machines:

http://mini-lathe.com
GadgetBuilder's MiniLathe and Little Workshop
mikesworkshop - Introduction

Or if YouTube is more to your taste:

https://www.youtube.com/channel/UC89zCBbbQ6L3yzu60NP-4Tw
https://www.youtube.com/channel/UCEpeQtxhVUTtMZzBpdegp-w

Hope you find this helpful.

Bill

 

[magpens]

Thank you very much for those links, Bill !!

 

[jalbert]

I use a Grizzly 7x14 for multi start, as well as 12tpi for the cap threads. I don't believe it's too fine for cap threads, and I've never had any complaints from customers regarding it.

 

[lign]

I use a Grizzly 7x14 for multi start, as well as 12tpi for the cap threads. I don't believe it's too fine for cap threads, and I've never had any complaints from customers regarding it.

Hi John, Thank you so much for your helpful reply. I took a look at your site and your work. Very beautiful! Those are some gorgeous pieces you have accomplished. The translucent ones are stunning. I especially love the clean nibs you are using that don't have the dreaded "Iridium Point Germany" on them. Do you use your 7x14 lathe to cut the threads into your pens to match the threads that these nibs come with?

Thanks!

 

[jalbert]

I use a Grizzly 7x14 for multi start, as well as 12tpi for the cap threads. I don't believe it's too fine for cap threads, and I've never had any complaints from customers regarding it.

Hi John, Thank you so much for your helpful reply. I took a look at your site and your work. Very beautiful! Those are some gorgeous pieces you have accomplished. The translucent ones are stunning. I especially love the clean nibs you are using that don't have the dreaded "Iridium Point Germany" on them. Do you use your 7x14 lathe to cut the threads into your pens to match the threads that these nibs come with?

Thanks!

Thanks Dave.
I use mostly unbranded Jowo #6 nib units, but use a tap to cut the threads inside the grip for the nib unit. I have cut them using the lathe in certain scenarios where the hole for the nib unit is stopped and the tap would bottom out, but in general it's easier just to use a tap for that part. All of my other threading though (cap threads, grip threads, finials, etc) are done on the lathe.
As someone posted earlier in this thread, I have begun to gravitate away from the triple start threads for the cap threads, and use a square form thread instead. I've found it ideal because as it's one start, facets or grain will align perfectly every time the pen is capped, as opposed to 1/n chance of alignment with multi start threads.

 

[lign]

Dave,

Your MicroMark will certainly do the job and do it well. Of course if you want a bigger lathe, have at it. We all want one!

There are makers here who do all of their threading on 7x Sieg lathes.

The Sieg lathes can be frustrating at times. Mine recently just locked up on me from debris in the leadscrew bearings. A little minor disassembly cleaning and lubrication can go a long way. Lesson learned!

There are a lot of tweaks out there to make the 7x's much more precise if you like fooling around with your machines:

http://mini-lathe.com
GadgetBuilder's MiniLathe and Little Workshop
mikesworkshop - Introduction

Or if YouTube is more to your taste:

https://www.youtube.com/channel/UC89zCBbbQ6L3yzu60NP-4Tw
https://www.youtube.com/channel/UCEpeQtxhVUTtMZzBpdegp-w

Hope you find this helpful.

Bill

Bill, yes that is very helpful. Thank you. After reading the replies here, I guess I need to do the grown-up, adult thing and learn to thread on my lathe before spending money on a bigger one. It is great to hear that people are using 12 TPI and don't find it frustrating with too many turns. I've wanted a milling machine for a lot of years, so maybe I'll spend the money on that instead.

I have hardly used my lathe at all except to make a really dandy little cannon that I'm proud of. I have been pretty frustrated with the lathe so I guess I need to learn about the modifications I can make to get it right and usable.

 

[lign]

.

Thanks!

Thanks Dave.
I use mostly unbranded Jowo #6 nib units, but use a tap to cut the threads inside the grip for the nib unit. I have cut them using the lathe in certain scenarios where the hole for the nib unit is stopped and the tap would bottom out, but in general it's easier just to use a tap for that part. All of my other threading though (cap threads, grip threads, finials, etc) are done on the lathe.
As someone posted earlier in this thread, I have begun to gravitate away from the triple start threads for the cap threads, and use a square form thread instead. I've found it ideal because as it's one start, facets or grain will align perfectly every time the pen is capped, as opposed to 1/n chance of alignment with multi start threads.

PatrickR posted a photo of a beautiful piece of yours that seems to have the "square form thread" you are referring to. Is that correct? Surely that is more coarse than 12 TPI? How do you cut those?

 

[jalbert]

.

Thanks!

Thanks Dave.
I use mostly unbranded Jowo #6 nib units, but use a tap to cut the threads inside the grip for the nib unit. I have cut them using the lathe in certain scenarios where the hole for the nib unit is stopped and the tap would bottom out, but in general it's easier just to use a tap for that part. All of my other threading though (cap threads, grip threads, finials, etc) are done on the lathe.
As someone posted earlier in this thread, I have begun to gravitate away from the triple start threads for the cap threads, and use a square form thread instead. I've found it ideal because as it's one start, facets or grain will align perfectly every time the pen is capped, as opposed to 1/n chance of alignment with multi start threads.

PatrickR posted a photo of a beautiful piece of yours that seems to have the "square form thread" you are referring to. Is that correct? Surely that is more coarse than 12 TPI? How do you cut those?

Yep, that one is an example of one that has a square thread so the grain lines up. It's 12 tpi. If I remember correctly, it uncapped with about 1.5 turns. Most of the fountain pen community I've dealt with likes the turn count somewhere between one and two turns. Of course TPI isn't the only determinant of the number of turns. You can always cut some of the threads away inside the cap if you want to reduce the number of turns. I cut the threads with internal/external tools that I ground myself.

 

[lign]

.

Yep, that one is an example of one that has a square thread so the grain lines up. It's 12 tpi. If I remember correctly, it uncapped with about 1.5 turns. Most of the fountain pen community I've dealt with likes the turn count somewhere between one and two turns. Of course TPI isn't the only determinant of the number of turns. You can always cut some of the threads away inside the cap if you want to reduce the number of turns. I cut the threads with internal/external tools that I ground myself.

Wow, now I remember why I loved this site so much! You folks are just brilliant!! So, you have a single start thread that is secure and aesthetic because of it's wide, square profile. You are correct about the number of turns. 1.5 is about perfect for me. My favorite Pelikan has 3/4 and that simply isn't enough. I lost two shirts to it and finally stopped carrying it when it stained my car seat and a pair of jeans. I just checked my most prized Pelikan, which is like-new and it has about 7/8's of a turn. I'm sure that's what my favorite had at the start of it's life, but a decade of use wore it down to a scant 3/4. 1 full turn is minimum. I'm going to do some experimenting!

 

[Hoeppr1]

.

Yep, that one is an example of one that has a square thread so the grain lines up. It's 12 tpi. If I remember correctly, it uncapped with about 1.5 turns. Most of the fountain pen community I've dealt with likes the turn count somewhere between one and two turns. Of course TPI isn't the only determinant of the number of turns. You can always cut some of the threads away inside the cap if you want to reduce the number of turns. I cut the threads with internal/external tools that I ground myself.

Wow, now I remember why I loved this site so much! You folks are just brilliant!! So, you have a single start thread that is secure and aesthetic because of it's wide, square profile. You are correct about the number of turns. 1.5 is about perfect for me. My favorite Pelikan has 3/4 and that simply isn't enough. I lost two shirts to it and finally stopped carrying it when it stained my car seat and a pair of jeans. I just checked my most prized Pelikan, which is like-new and it has about 7/8's of a turn. I'm sure that's what my favorite had at the start of it's life, but a decade of use wore it down to a scant 3/4. 1 full turn is minimum. I'm going to do some experimenting!

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