Threads for boxes....

[Doug Rasmussen]

The picture shows my test pieces of a thread style I've been thinking about for a few years. It's a modification of a bottle thread commonly found on food jars. About 270 degree rotation from start to fully tightened lid. Equivalent to a 4 threads per inch conventional thread (the thread jigs I'm aware of typically with have from 8 to 16 tpi).

The thread action is different than a conventional 60 degree thread. The two pieces are very loose until about the last few degrees of turning. The looseness should allow for some distortion of the pieces without causing binding. Smooth to turn with very little friction because you only have one point of contact on the single thread turn on each of the two pieces. As the thread bottoms out the pieces center on each other.

This style thread may solve some of the things I've never liked about threaded lids. First is the single turn (5 or more turns to get a lid off gives me carpal tunnel syndrome just thinking about it). The looseness should allow for some wood movement. And there's less chance of chipping since the thread form doesn't have the pointed tips.

These could be cut on a threading jig provided you have the special cutter, and most important you'd need a 4 pitch lead screw.

The two pieces in back are punky Cherry which didn't cut well, still very usable. The front enter piece is Eastern hard maple, much better finish and smoothness, although with my poor photography skills it's hard to tell the difference.

 

[Bill Boehme]

I can envision cutting the internal thread, but the external thread seems like it would be a more challenging task.

 

[john lucas]

I like it. Now if someone will just produce a jig to cut them. I made notched lid once. Drop it on and give it a 1/4 turn and it locked. Too much trouble to make for commercial sale but was fun trying it.

 

[Pete Blair]

Great idea but if the wood moves I would think it would effect the alignment of the grain.

 

[robo hippy]

I am wondering how you time the threads to get the grain to line up... Most of the time this means adjusting the shoulder on the outside down a bit. For a 1/4 rotation to line up the grain, you would have a lot of work to do.

robo hippy

 

[Doug Rasmussen]

I can envision cutting the internal thread, but the external thread seems like it would be a more challenging task.

Bill, with a thread cutting jig I envision a cutter something like this one from the Grizzly catalog. The radius would have to be smaller and the cutter taller with more cutting edge above and below the radius. Even then a little hand clean up might be needed.

My test pieces were cut in the CNC with a more complicated method that couldn't be duplicated with a simple threading jig.

If I thought there was enough market to get involved pairs of male/female glue in inserts similar to the brass ones mentioned in another thread could be made. Using as thin as reasonable ABS plastic that would flex with any wood movement might be possible.

 

[Doug Rasmussen]

Pete and robo, I wasn't thinking about grain alignment. but you're right, any oval-ness developing in either piece would cause misalignment..

 

[Bill Boehme]

All this fretting over the number of turns in threaded boxes Is missing the point that the charm is actually having handmade threads in a wooden box. Anything less than one turn and you may as well have a friction fit lid. Just my 2¢.

 

[john lucas]

I agree with Bill. There's kind of fine line between having a screw fit that just takes a few turns that are satisfying vs 10 turns that gets tedious. That being said when you attach something with a bayonet and lug style system you get that feeling of quality. Unfortunately because of wood movement that won't last long in a wooden piece unless you had metal inserts.

 

[robo hippy]

Timing the threads would not be a problem if you use a different wood for top and bottom. Inserts are another way... Boxes are very time consuming, making them more for fun than for profit...

robo hippy

 

[john lucas]

We had a demo by Chris Stott years ago on box turning. He turned a snap fit lid box in 1 minute just to show it could be done. He was obviously very quick at making boxes. He said he tried selling bowls and other turned items but they sold kind of slow because of the price he had to ask. He could make a box in 5 or 10 minutes and sell if for $17 and sell them quickly all day long. He said it was much more profitable for him and his time in the sales booth was much more exciting because he was constantly making a sale. Of course that was almost 20 years ago when I saw that demo.

 

[hockenbery]

Jack Roberts a Florida guy who does a lot of boxes is not as fast as Crist Scott but he sells a lot of boxes.

Jack does a great box demo. In his demo he talks and shows slides about the different style boxes he turns and how he holds the blanks on the lathe.
His quick production box - under 20 minutes - does not require any grain alignment.

His slower boxes align the grain better. His near perfect grain alignment box is done using a turned wood insert for the lid fit so only a thin saw kerf of wood is lost for the grain match. This takes a lot of time.

 

[Mike Johnson]

With a little practice you can turn small boxes quickly, the trick is having a streamlined method in mounting the blank and cutting a tenon quickly. Starting with a round billet speeds the process, I have purchased round teakwood drops from a company and these were quick to mount in an adjustable chuck and quick in turning small lidded boxes. Certain wood types are also easier to work with when turning boxes. You can also incorporate the finishing process while on the lathe to speed up the entire process, with a friction polish you can finish a small box quickly and move onto the next item.

 

[Bill Boehme]

If you've seen the GEICO sloth commercial, that's me. I could do an all day demo on turning a pen.

View: https://www.youtube.com/watch?v=Gl3l6Bq6bMo

 

[Dean Center]

You can also incorporate the finishing process while on the lathe to speed up the entire process, with a friction polish you can finish a small box quickly and move onto the next item.

A more durable finish the on the outside of boxes that will actually be used seems appropriate. Like Mike, I think a friction polish is dandy on the inside, where durability is not an issue. It's fast and attractive.

 

[Doug Rasmussen]

Everybody loves boxes. IMO small turned, lidded boxes could be a profitable product. They're made from what could be considered cutoffs or scrap compared to the blanks needed for large turnings.

You might have to forget most of what you know about traditional woodturning though. Do your hollowing with large drill bits to hog out the bulk of the material. Use some sort of XY cross slide mounted on the lathe to establish repeatable lid fitting diameters instead of trial fittings. Some "turnings" can be better made on non-lathe machines with work holding jigs. CNC routers have even gotten down in price to less than a high end wood lathe, not much turning that can't be done on one.

Back in the day Delta published a series of books, "Getting the Most Out of Your...." shaper, table saw, lathe, drill press, etc. They're long out of print, but readily available on the used book market. Those had some really clever ways to adapt non conventional production methods to the various machines, like turning on the shaper and table saw.

 

[Gerald Lawrence]

You might have to forget most of what you know about traditional woodturning though. Do your hollowing with large drill bits to hog out the bulk of the material. Use some sort of XY cross slide mounted on the lathe to establish repeatable lid fitting diameters instead of trial fittings. .

Doug could you elaborate on use of a cross slide for fitting tops to boxes? You have intrigued me.

 

[Doug Rasmussen]

Doug could you elaborate on use of a cross slide for fitting tops to boxes? You have intrigued me.

Here's an eBay picture of the vintage Delta cross slide they offered for their lathes. It has two axes of travel with the top slide being able to swivel for angular cuts. These could be adapted to large swing lathes by using a wood spacer block to bring the tool up to the lathe's centerline. With the micrometer dials it's easy to repeat a diameter from turning to turning. There's one on eBay now for $380.

Google on "Grizzly cross slide" and you'll find a whole variety of two axis slides that can be fitted with a tool post for lathe use. They won't have the swiveling top slide though. Prices vary starting under $100.

Some of the ornamental turning folks (those with deep pockets) use Hardinge cross slides. Similar to the Delta unit, but very expensive,

 

[Bill Boehme]

Back in the day Delta published a series of books, "Getting the Most Out of Your...." shaper, table saw, lathe, drill press, etc. They're long out of print, but readily available on the used book market. Those had some really clever ways to adapt non conventional production methods to the various machines, like turning on the shaper and table saw.

It may have been the same as the small books that Sears published. I have several of them if I can remember where they are.

 

[Gerald Lawrence]

Thanks Doug. Interesting but more than I want to put into boxes.

 

[Mike Johnson]

Free handing with a tool on the lathe is hard to beat, there are a few occasions and applications where a cross slide comes in handy. On occasion I will use my metal lathe to perform an accurate machining process when needed. I usually don't like to make this a habit as wood shavings and wood dust to not go well with a metal cutting lathe. For that reason it would be handy to have a cross slide for one of my wood lathes some day.

 

[john lucas]

For not much more than you can buy a cross slide you can buy this whole jig for cutting threads. It does a good job and will fit any lathe.
https://www.chefwarekits.com/ez-threading-pro-xl-jig-thread-cutter.html
Like I said the main reason I went with a threading jig is simply because woods that are hard enough to hand chase a good thread consistently are a pain to get hold of and expensive. I turn a lot of boxes both threaded and unthreaded. With my jig I can use almost any wood. For boxes the wood has to be dry and it's hard to find dry wood in the sizes that I like for my boxes so I cut and dry my own. Obviously takes several years to dry a box but I've been doing that for many years now so I have a fair amount of dry stock.
I can hollow a box with a spindle gouge as fast or faster than you can drill it. Drilling boxes heats up the wood and invites checking. I hollow with the spindle gouge or Hunter Hercules. The I finish up the inside with a Hunter #5 and can sand the inside with 220 or higher. The Hunter tool leaves a finish good enough that sometimes I won't sand.

 

[Gerald Lawrence]

I can hollow a box with a spindle gouge as fast or faster than you can drill it. Drilling boxes heats up the wood and invites checking. I hollow with the spindle gouge or Hunter Hercules. The I finish up the inside with a Hunter #5 and can sand the inside with 220 or higher. The Hunter tool leaves a finish good enough that sometimes I won't sand.

John i have found that just directing a air nozzle into the drill all heat is relieved and chips are exhausted also so the forstner gets most of it done quickly. Will still need some gouge work for the hole in the bottom.

 

[Don Wattenhofer]

Here's an eBay picture of the vintage Delta cross slide they offered for their lathes. It has two axes of travel with the top slide being able to swivel for angular cuts. These could be adapted to large swing lathes by using a wood spacer block to bring the tool up to the lathe's centerline. With the micrometer dials it's easy to repeat a diameter from turning to turning. There's one on eBay now for $380.

Google on "Grizzly cross slide" and you'll find a whole variety of two axis slides that can be fitted with a tool post for lathe use. They won't have the swiveling top slide though. Prices vary starting under $100.

Some of the ornamental turning folks (those with deep pockets) use Hardinge cross slides. Similar to the Delta unit, but very expensive,




View attachment 26170

I have had a delta cross slide that I bought from a used tool store for about 20 years and in that time I have used it for many tasks but never to bore accurately since it is more trouble to set up than it is worth. The most recent use was to make V shaped cuts for inlays using a small router mounted on the cross slide.

 

[Doug Rasmussen]

For not much more than you can buy a cross slide you can buy this whole jig for cutting threads. It does a good job and will fit any lathe.
https://www.chefwarekits.com/ez-threading-pro-xl-jig-thread-cutter.html
Like I said the main reason I went with a threading jig is simply because woods that are hard enough to hand chase a good thread consistently are a pain to get hold of and expensive. I turn a lot of boxes both threaded and unthreaded. With my jig I can use almost any wood. For boxes the wood has to be dry and it's hard to find dry wood in the sizes that I like for my boxes so I cut and dry my own. Obviously takes several years to dry a box but I've been doing that for many years now so I have a fair amount of dry stock.
I can hollow a box with a spindle gouge as fast or faster than you can drill it. Drilling boxes heats up the wood and invites checking. I hollow with the spindle gouge or Hunter Hercules. The I finish up the inside with a Hunter #5 and can sand the inside with 220 or higher. The Hunter tool leaves a finish good enough that sometimes I won't sand.

john, I think we're talking about different degrees of production set ups. In production you'd use a drill with air blown through it to blow the chips out and secondly to cool the drill and wood, chip clogging causes friction and heat. Drilling from the tail stock you can do a 2" hole as fast as you can crank the tails stock hand wheel.

With a cross slide mounted tool it's totally different than a hand held tool. No riding the bevel, etc, you don't worry about dig ins and catches. They can't happen because the tool is rigidly held. Use aggressive cutting high positive carbide inserts like Hunter uses except mounted flat which would tend to catch if hand held. Using a 1/4" round insert you could feed down the inside wall of a drilled hole easily taking 1/8" off leaving a smooth finish not needing sanding at a repeatable diameter.. Once you got to depth feed across the bottom to the center and you're done. And you have a nice radius in corner matching the radius of the insert.

With both of the above I doubt you could come any where near the time efficiency with your methods. Worst case, it could take up to a minute to drill and finish cut. And none of this needs to be expensive. You'd have to fabricate the drill by brazing an air tube along the shank of a standard wood bit. The cross slide can be as cheap or as expensive as your tastes (you do want one that cranks smoothly with minimal slop in the lead screws).

Maybe the biggest plus of this is only very basic skills needed, no special cutting techniques or sharpening of bevels sort of stuff. I know a lot of turners enjoy doing it the traditional ways. I just happen to enjoy the challenge of finding easier ways.

 

[hockenbery]

@Doug Rasmussen this is similar to what duplicating lathes do.
The surfaces are rarely as good as what can be achieved by hand.

Used mostly in furniture, architecture, and sports equipment the surfaces are good enough.

Also some ball cutting jigs are similar in use.

 

[john lucas]

Feeding the cutter flat carbide or not you get a finish that I find unacceptable and would have to sand a great deal. Sound like your talking making a ton of boxes and probably similar shapes meaning you can't change the shape to make the figure in the wood stand out better. Not saying production of that sort is out of line but it's more like production bowls that all have the same shape. My boxes all vary so each customer gets something unique.

 

[Bill Boehme]

With a cross slide mounted tool it's totally different than a hand held tool. No riding the bevel, etc, you don't worry about dig ins and catches. They can't happen because the tool is rigidly held. Use aggressive cutting high positive carbide inserts like Hunter uses except mounted flat which would tend to catch if hand held. Using a 1/4" round insert you could feed down the inside wall of a drilled hole easily taking 1/8" off leaving a smooth finish not needing sanding at a repeatable diameter.. Once you got to depth feed across the bottom to the center and you're done. And you have a nice radius in corner matching the radius of the insert.

Regardless of how rigid the cutter might be, wood is a relatively soft and flexible medium. Aggressive feeding can set up significant vibration in the wood.

For what I do where I could count the total number of boxes that I've made on my fingers and toes, the borderline Neanderthal approach works just fine. And, none of the boxes that I've made have cylindrical walls.

A Real Nut Case:

A Real Nut Case Exposed:

It's a burr oak acorn which is golf ball sized.

 

[Gerald Lawrence]

Not sure what kind of bit y'all are talking about drilling with but a couple days ago I drilled a walnut box with 1 7/8 forstner and the cut was as smooth as glass. Mind you I did hollow it a bit more but if I wanted straight sides , no tearout, and minimal sanding would have been needed.

 

[Bill Boehme]

I'm just talking about a spindle gouge. I believe that Doug is talking about a carbide cutter with some sort of automatic feed for rapid hollowing. Forstner bits are good especially the Colt MaxiCut bits which are the best that I have ever used.

 

[Don Wattenhofer]

I am not sure if I am in the right discussion but I have been turning what I call urns with threaded lids since the early 1990's and never did a straight inside. The drilling that I do is mostly to establish the depth and provide a place to start the hollowing process. The drill that I have used since I purchased them at Boeing Surplus (Tacoma WA symposium) are gun drills that have a single straight flute and hole through to the cutting tip. The drill is mounted to a custom holder that also has a hole through it and an air gun mounted. The process is to make a starting hole with my 1/2" detail gouge and then push it into the turning with the air on. The 3/4" gun drill will make a hole about 11" deep in about 1/2 minute. The hole can be enlarged at the entry end using back cutting with the detail gouge and then whatever works farther in. The surface for the female thread is trued up with the long point on a small 1" skew and if the wood is soft I will soak it with CA. The turning is moved to my metal lathe to cut the threads. The metal lathe has a small trim router mounted on the cross slide set for 30 degrees. The first point was a dislike for multiple turns so once the male thread is made just counter bore the female thread until 1 to 2 turns is all it takes and don't use any thing finer than 10 threads per inch.

 

[Doug Rasmussen]

I'm surprised at the comments about unacceptable finishes using the methods described above and the suggestion better finishes can be achieved with hand tools. All I can conclude is either you've never seen the finishes or my explanation wasn't clear.

An example most of you likely have seen would be the finishes on ornamental turnings. Same situation, ultra sharp rigidly mounted tools taking micro thin shavings off with a controlled feed rate.

 

[Bill Boehme]

An example most of you likely have seen would be the finishes on ornamental turnings. Same situation, ultra sharp rigidly mounted tools taking micro thin shavings off with a controlled feed rate.

Maybe I misinterpreted your earlier comments as advocating an automated system to make the process much faster than doing it by hand. From what I have seen of Bill Ooms videos his ornamental process isn't very fast.

 

[john lucas]

I only have cheap Forestner style bits and they don't leave a finish I like. I have used other bits and they leave a better finish but still have score lines going down the side. I like my boxes to look like they are sanded to at least 220 grit and higher if I can get it.

 

[Gerald Lawrence]

This is surface I get on pecan with HF bits.

 

[Bill Boehme]

How well do they hold up? Do you have other Forstner bits that you can compare to the HF bits? Also, how about drilling end grain which is normally what we would want to thread ... and is the acid test for Forstner bits.?

 

[john lucas]

Gerald I see score lines and tearout. Not bad but not as good as want my boxes to be. You can sand it out of course but that's why I use the Hunter tools, to reduce the sanding to just touch up.

 

[Gerald Lawrence]

How well do they hold up? Do you have other Forstner bits that you can compare to the HF bits? Also, how about drilling end grain which is normally what we would want to thread ... and is the acid test for Forstner bits.?

Bill I have a smaller set of Lee Valley but only up to 1 inch since that is what I once used a lot of and had to replace.

Gerald I see score lines and tearout. Not bad but not as good as want my boxes to be. You can sand it out of course but that's why I use the Hunter tools, to reduce the sanding to just touch up.

John I did not look that close at the lower part just the upper. Did one a few days ago in walnut and it was almost pristine and slight gloss. And no I would not use just the bore on a box I do because I like barrelled or coved sides on these small projects. However I notice that doing the laminated boxed like this some woods will give significant tear out inside. Oh and I use Hunters also, and just put my last new cutter on since I waited way too long to do that.

 

[robo hippy]

Haven't tuned into this one in a while...

I have seen Chris Stott demo, and it was interesting. If I had turned as many boxes as I have bowls, I would be a lot faster. Probably the same for him with bowls.

Never understood using a forstner bit to turn out the inside of any form, mostly because hand tools are much faster, at least for me, though maybe not as accurate for straight as the bit.

Still considering the X/Y jig... I have seen some home made ones that were kind of ugly, but worked great... I do like to finish cut tenon and recess with a NRS.

robo hippy