• Beware of Counterfeit Woodturning Tools (click here for details)
  • Johnathan Silwones is starting a new AAW chapter, Southern Alleghenies Woodturners, in Johnstown, PA. (click here for details)
  • Congratulations to Paul May for "Checkerboard (ver 3.0)" being selected as Turning of the Week for March 25, 2024 (click here for details)
  • Welcome new registering member. Your username must be your real First and Last name (for example: John Doe). "Screen names" and "handles" are not allowed and your registration will be deleted if you don't use your real name. Also, do not use all caps nor all lower case.

Thread cutting jigs

RichColvin

Super Moderator
Staff member
OTI Member
Joined
Mar 13, 2016
Messages
667
Likes
497
Location
Marysville, OH
Website
www.colvintools.com
Re the cnc rose engine lathe thread cutting: The CNC machine tool industry has a tool called a thread mill and it is used with the part stationary and the thread cut by manipulating the X Y & Z axiss so the question is are the threads cut that way or are you adding a rotary axis to drive the work piece into the cutter?

The cutter spins, and the piece rotates slowly whilst advancing along the Z axis. Here's a video of Pat Miller doing it on his MDF rose engine lathe:

View: https://youtu.be/W9ZNgIiwwNI


and here's a video of David Lindow doing it on the Lindow-White rose engine:

View: https://youtu.be/8E1sGqcDW8A
 
Joined
Dec 5, 2015
Messages
724
Likes
342
Location
Seattle, WA
You know, for the cost of one of the high end models, you could put together an MDF rose engine lathe, and get all the threading options you’d want + a whole lot more!

Rich, thanks for posting the rose engine threading videos. The master and follower technique for thread cutting was/is widely used in the metal working industry, maybe it even predates the first rose engines.

I take issue with the idea the average wood turner with little to no metal working capabilities could build a rose engine capable of the thread cutting shown for less cash outlay than a ready made threading jig.
 
Joined
Jul 19, 2018
Messages
1,686
Likes
2,077
Location
Ponsford, MN
The cutter spins, and the piece rotates slowly whilst advancing along the Z axis. Here's a video of Pat Miller doing it on his MDF rose engine lathe:

View: https://youtu.be/W9ZNgIiwwNI


and here's a video of David Lindow doing it on the Lindow-White rose engine:

View: https://youtu.be/8E1sGqcDW8A
I watched both videos and my impression is it is just a hybrid of the Klein style or maybe the Klein was derived from it. The following link details the threading operation on a machine lathe where the only change necessary for wood is to substitute a 60 degree thread cutting bit and a router mounted on the cross slide in place of the tool bit shown https://smithy.com/machining-handbook/chapter-3/page/24 . It is possible to add a lead screw linked to the headstock spindle to a wood lathe to drive a fixture with the router such that it moves along the X axis, which was the method I used on my first setup before I had a machine lathe. The machine lathe is so much more versatile for thread cutting, because you can set many different pitches Plus many of the newer machines have metric and inch pitches.
 
Joined
Aug 14, 2007
Messages
5,436
Likes
2,792
Location
Eugene, OR
Getting back to Don's comment about timing the threads, he says that it would 'average' 1/2 of the thread distance. When I took a work shop with Bonnie Klein, many years ago, she said it was impossible to time the threads so they would line up predictably. After thinking about it for some years, I figured out a method so that mine take about 5 minutes on the clock of adjustment to get the grain to line up. I figured it out from thinking that when I want to make repeated length cuts on the table saw or the chop saw, I used stop blocks, which is a block clamped into place so I don't have to measure each one. Applying that to box threading, in order to use a stop block, I needed a measure device. So, I line the top and bottom up with the grain matched, and put a pencil line on both top and bottom for a reference point. For the stop block, I use the ruler from a tri square, which is about 1 inch wide and about 3/32 thick. First cutting the threads on the lid, I slide the X/Y jig up to the cutter and space it the thickness of the ruler away from the cutter. The pencil line is at 12 o'clock. Cut the threads. When cutting the bottom, Same method, but I have the pencil mark at about 5 minutes before 12. Simple, and repeatable, and if you ever have to remount, as long as the pencil lines are still on, it is simple and easy and repeatable. You may have to experiment a bit to make sure it works for different thread counts, but with mine and the 16 tpi, I never have to go more than a light NRS scrape on the shoulder to get the fit right. I never try to get it perfect from the cutter and leave the adjusting for the perfect fit.

robo hippy
 
Joined
Jul 19, 2018
Messages
1,686
Likes
2,077
Location
Ponsford, MN
Getting back to Don's comment about timing the threads, he says that it would 'average' 1/2 of the thread distance. When I took a work shop with Bonnie Klein, many years ago, she said it was impossible to time the threads so they would line up predictably. After thinking about it for some years, I figured out a method so that mine take about 5 minutes on the clock of adjustment to get the grain to line up. I figured it out from thinking that when I want to make repeated length cuts on the table saw or the chop saw, I used stop blocks, which is a block clamped into place so I don't have to measure each one. Applying that to box threading, in order to use a stop block, I needed a measure device. So, I line the top and bottom up with the grain matched, and put a pencil line on both top and bottom for a reference point. For the stop block, I use the ruler from a tri square, which is about 1 inch wide and about 3/32 thick. First cutting the threads on the lid, I slide the X/Y jig up to the cutter and space it the thickness of the ruler away from the cutter. The pencil line is at 12 o'clock. Cut the threads. When cutting the bottom, Same method, but I have the pencil mark at about 5 minutes before 12. Simple, and repeatable, and if you ever have to remount, as long as the pencil lines are still on, it is simple and easy and repeatable. You may have to experiment a bit to make sure it works for different thread counts, but with mine and the 16 tpi, I never have to go more than a light NRS scrape on the shoulder to get the fit right. I never try to get it perfect from the cutter and leave the adjusting for the perfect fit.

robo hippy
I guess I never thought to try and cut the average. There is another factor that will have a bearing on grain alignment, that being the length of the male thread may make alignment impossible unless you are using very straight grained wood. The use of two contrasting woods for the body and lid eliminates the problem entirely and may even enhance the design.
 

RichColvin

Super Moderator
Staff member
OTI Member
Joined
Mar 13, 2016
Messages
667
Likes
497
Location
Marysville, OH
Website
www.colvintools.com
I watched both videos and my impression is it is just a hybrid of the Klein style or maybe the Klein was derived from it. The following link details the threading operation on a machine lathe where the only change necessary for wood is to substitute a 60 degree thread cutting bit and a router mounted on the cross slide in place of the tool bit shown https://smithy.com/machining-handbook/chapter-3/page/24 . It is possible to add a lead screw linked to the headstock spindle to a wood lathe to drive a fixture with the router such that it moves along the X axis, which was the method I used on my first setup before I had a machine lathe. The machine lathe is so much more versatile for thread cutting, because you can set many different pitches Plus many of the newer machines have metric and inch pitches.

Right you are. And thank you for the link to smithy.com. That is one I’ll bookmark for later. Looks like a lot of good information there.
 
Back
Top