Question Regarding Cutting Threads in Domestic Woods with a Jig

[Glen Blanchard]

I have heard a couple differing opinions regarding the best thread pitch (using a jig – not hand chased) in domestic woods for boxes and finials. I am wondering if there is a consensus of sorts. 12 or 16 tpi? Other?

[Dwight Rutherford]

I turn with a jig and use domestic hardwoods and like 12tpi, the threads are more robust than 16tpi and less prone to chipping.IMO

[Glen Blanchard]

I turn with a jig and use domestic hardwoods and like 12tpi, the threads are more robust than 16tpi and less prone to chipping.IMO

Thanks, Dwight. Which jig are you using?

[Dwight Rutherford]

I use a jig that a friend cobbled together. It’s a Carbatech and router set up.

[Richard Madden]

My homemade threading jig makes 14tpi and works well with domestic hardwoods. Given a choice between 12 or 16tpi, I'd go with the 12tpi for the same reasons mentioned by Dwight.

[Bert Delisle]

I have heard a couple differing opinions regarding the best thread pitch (using a jig – not hand chased) in domestic woods for boxes and finials. I am wondering if there is a consensus of sorts. 12 or 16 tpi? Other?
I use 16tpi for under 2" boxes and needle cases, and use 10tpi for most other items. The jig is a Chefware Kits threading jig. Pricey but it works and is repeatable. As with any jig a bit of a learning curve but worth the effort. I made a ships wheel ring to fit my chuck as the cutter has a tendancy to grab and want to climb, it actually unthreaded the chuck from the jig once. Now I feed the cutter with the chuck wheel not the jig handle.

[JohnC Lucas]

I have the Baxter threader and use 16tpi for all my boxes. I have hand chasing tools from 11 to 20 but still prefer 16 for most. I would probably use 10 or 12 for larger boxes but most of mine are 2 1/2" or under.

[Bill Blasic]

I also have and recommend Baxter Thread Master. I too mainly use the 16 tpi head but also have the 8, 10 and 24 tpi heads. Wood type, species and use may dictate what threads you might want to use. I'll tell you this, so far I have not found a species that I cannot thread on the Baxter.

[Glen Blanchard]

Thanks very much for the informative replies. I have the Chefware Kits XL Pro and have used it a few times using 16 tpi on cherry. It works but I am getting some chipping on the peaks of the cherry threads and thought that going down to something like 12 tpi might minimize that. (Yes, I understand that the use of CA would be another strategy.) A new 12 tpi spindle for that jig is $180. One of the things I dislike about the jigs that are mounted in the banjo is that they have to be oriented for parallel each time - once for the lid and once for the bottom. As it is impossible to get identical orientations both times, I find the Baxter more appealing as it eliminates that variable. I am hesitant to invest another $180 into the Chefware jig and am thinking it would be smarter for me to bite the bullet and invest those funds into a Baxter. The Baxter is certainly pricey but it appears that it would be more repeatable and that it has the potential for yielding better results.

I invite any comments. John? Bill?

[Bill Blasic]

Glen, I did an article on the Baxter for More Woodturning Online. I cannot really explain just how well done it has been thought out and manufactured. I can't imagine someone not loving this jig if they had it. The simple thing that makes it repeatable for checking the thread size takes but seconds. I initially bought mine for my DVR3000 and then asked Victor if he could make me an add on that would allow me to use it on my Powermatic, Bingo works perfectly. I can thread 5" down to 1/4" and do so without qualms. Yes it is pricey and the additional threading heads cost the same as what you are looking at with yours but the Baxter Thread Master is built to be true and to last forever. My Baxter is always on my DVR300 unless we have a hands on but as soon as the hands on is done it goes back on the lathe. It is not often that you hesitate over a purchase because it is quite expensive that once you have it you know that it was money well spent.

[Glen Blanchard]

Glen, I did an article on the Baxter for More Woodturning Online.

Do you happen to have a pdf of that article that you could email me? If so, I'll send you my email address.

[Reed Gray]

Biggest difference I can see in the tpi is how far you have to adjust the shoulder to get the grain to line up. 16 tpi means at most you have to take it down almost 1/16 of an inch. I haven't threaded in a while, but have the Bonnie Klein jig. The X/Y jigs are fairly common and not all that difficult to make. I won't make threaded boxes over about 1 1/4 to 1 1/2 inch diameter because wood movement can make them impossible or at least difficult to open. Found that out the hard way once.... I don't understand the pivoting type of thread cutting jigs. I do remember Bonnie commenting that there was no predictable way to 'time' the threads so grain would line up, so one time you would have to adjust the shoulder just a hair, and the next time you would have to adjust it almost the entire 1/16 inch. Royal pain... Well, I figured it out. You need a repeatable start/stop point for advancing the lid and bottom into the cutter. So, I would use a pencil mark on the two pieces of the box. Rotate the box part on the jig till the mark is at 12 o'clock. Then slide the jig up to the cutter and use about a 1/16 inch spacer between the cutter and the box part (I use the metal ruler from a tri square). Cut the threads. Lid generally cuts first. For the second part of the box, use the same method, but instead of starting with the pencil mark at 12 o'clock, I would start it at 11, and this leaves the shoulder adjustment to maybe 5 minutes of rotation. Handy thing about this is that if you make any mistakes, it is simple to remount as long as the pencil marks are still on the blank....Now, I want to see some one make the cuts for threading and friction parts dead square and parallel...

Side note, if you need 'justification' for new tools for the shop, look up Boxmaster Tools, www.boxmastertools.com He will be taking over D Way tools in the near future... Chatted with him at the Symposium briefly, seems like a good man...

robo hippy

[JohnC Lucas]

If your getting chipping there are a couple of options. Number one don't cut all the way to a point. Many woods just won't take a good point. Either leave it slightly flat on top or knock off the points with sandpaper after words. Don't feed the wood past the cutter at a fast rate. Make several passes instead of one deep pass. After the first of second pass soak it with CA. Like Bill I have threaded rediculously soft woods using the Baxter threader and the Chefwarekits threader. I do cheat a little but I don't think it makes much difference. I use a router as my headstock and built a fake lathe to hold the Baxter threader. I thought turning the cutter at 23,000 rpm would leave a cleaner thread in soft woods than using my lathe at 3,000. I really can't tell the difference. The biggest advantage is removing the wood from my lathe and taking it directly to the router lathe with threader. I don't have to stop and set anything up.

[John K Jordan]

...The biggest advantage is removing the wood from my lathe and taking it directly to the router lathe with threader. I don't have to stop and set anything up.

I also found that to be a big advantage. I also use the Baxter jig, in my case, on a second lathe. Besides not having to set it up several times (especially when threading several boxes) this let me test the fit and shave a bit on one or both parts to make the grain/figure line up. (I left the box and lid mounted in chucks.)

[Glen Blanchard]

I use a router as my headstock and built a fake lathe to hold the Baxter threader.

Very interesting idea, John. Do you have any photos of your setup?

[Marvin Hasenak]

Very interesting idea, John. Do you have any photos of your setup?

If you want to go that route check this link out. http://scottingham.com/thread.html
It has another never ending money pit that you can chase the dreams in.

[JohnC Lucas]

I made it out of angle iron. I got anal and hand filed the exact size between the ways. I don't think it needed that.

[Dwight Rutherford]

388477The one I use is similar;

[Glen Blanchard]

Dwight, John - Very resourceful. Kudos to you both. Great idea.

John - I presume you had the Baxter prior to building your threading station, correct?

[Dan Henry]

If you have some chippy wood soak the area for threads with thin CA glue before cutting the threads and after the theards are cut soak the threads one more time, Do not change the set up and soak with clue, let the glue dry and recut the threads. I have cut threasd in some very soft wood using this the idea.
Dan

[Reed Gray]

If my threads are chipping, I cut them about half way down, then put some walnut oil on the threads for the next few passes. Pretty much eliminates chipping. Nice set up John. I would think the high speeds of the router would be too much.

robo hippy

[Doug Rasmussen]

Something I don't ever recall seeing in recommendations for wood threading is to use a climb cut. A climb cut can be visualized as the direction of cut that you're warned not to use when routing the edge of a board with a hand held router. Climb cuts have a strong tendency to try and self feed the tool such that you can lose control due to the strong self feeding force.

With the relatively small amount being removed with rotating threading tools the force trying to self feed will be minimal enough you should be able to easily control it with a threading jig (some threading jigs have a method to adjust tightness of the screw, tighter is better for control). I don't have time right now to show a diagram of which side the cutter should be on to accomplish climb cutting. If you hold a cutter near a threaded container lid (something from the refrigerator, for instance) should give an idea of how to accomplish the climb cut.

I do virtually all my woodworking on CNC machines where climb cutting is a no-brainer. It gives far less chipping and tear out even when and especially when cutting against the grain.

[Glen Blanchard]

Something I don't ever recall seeing in recommendations for wood threading is to use a climb cut.

Doing a climb cut would require a relief channel be cut at the 'ending point' of the threaded surface (a technique that I have seen advocated numerous times anyway) prior to engaging the cutter. As long as some relief has been provided in which to place the teeth of the cutter, I don't see why a climb cut could not be made as long as incremental and small passes are made so as not to be dangerous.

I wonder if there would be a difference in the quality of cut.

[Doug Rasmussen]

Doing a climb cut would require a relief channel be cut at the 'ending point' of the threaded surface (a technique that I have seen advocated numerous times anyway) prior to engaging the cutter. As long as some relief has been provided in which to place the teeth of the cutter, I don't see why a climb cut could not be made as long as incremental and small passes are made so as not to be dangerous.

I wonder if there would be a difference in the quality of cut.

Yes, definitely better quality of cut and less chance of chipping the thread crests. There also may be longer cutter life too. At least a metal cutting climb cut gives longer tool life since the cutter doesn't rub before biting into the work.