Threaded boxes

[Michael Beswick]

I am developing (!) my skills with threaded boxes.

I try to use "interesting" /figured wood and attempt to match up top and bottom. Clearly any lidded box loses a portion at the join/overlap. I am trying to minimise this by:

Cutting the top off using a band-saw once the spigots have been made at each end.

Starting the thread cutting at the same point at top and bottom, so minimal trimming for pattern alignment.

Using a 1.6mm parting tool for the relief at the base of the threads in the male spigot. Experience has shown I need about 1-1/2 "widths" of this so about 2.4mm relief. This is to allow the body of the cutter clearance. The cutting tips, when engaged to the 5 clicks, are thinner at that point than the overall thickness of the cutter. (see pic Box 1) Hence the need for the wider relief recess

By using a deeper threaded recess in the top there is no need for the relief in the top. I am using the 16 tpi jig.

I am using only 1-2 threads as my test market said more than 3or 4 “wrist twists” is irritating (and most non wood turners don’t care about my expertise!)

Is there a clever trick I am missing?

Thanks

Michael


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Michael Beswick
07774 801983

 

[hockenbery]

I am developing (!) my skills with threaded boxes.

I try to use "interesting" /figured wood and attempt to match up top and bottom. Clearly any lidded box loses a portion at the join/overlap. I am trying to minimise this by:

Cutting the top off using a band-saw once the spigots have been made at each end.

Starting the thread cutting at the same point at top and bottom, so minimal trimming for pattern alignment.

It’s nearly impossible to get perfect grain alignment whe you remove a section of wood.
Two things to consider.
1. Adding an insert to cut the treads on will limit the lost wood to the bandsaw kerf + a bit of clean up.

2. Choose a cut line where major grain lines are vertical over the thread space
Making the lid joint over the yellow space will look better but not terrific.

 

[john lucas]

I use a really thin parting tool. I make a cut about 3/8" deep. Then I use this area as a fulcrum when I push the tool in further I make a cut to the left and then to the right. Each time I go in deeper I don't make the initial cut wider.
Then I make a threaded insert for the male thread. It is epoxied in place using the lid to hold it. This is the closest I can get to grain alignment when I have twisted grain or patterns.
The other way us to use a contrasting piece of wood to fill in the space your parting tool leaves. Kind of like gluing on a washer to fill the gap. Make it too large. Screw tge lid on and check for alignment. Remove a little woid and check the alignment again. Sneak up on a perfect fit and alignment.

 

[Richard Findley]

Best thing I can suggest beyond using straight grained timber is to turn a little step detail at the join that shows the join as a detail but also confuses the eye just enough to hide a slight grain mis-match. It’s a technique I first saw Ray Key use.

 

[Richard Findley]

An example of the sort of join feature I mean. This is a threaded box.

 

[Dennis Weiner]

@Michael Beswick The method I employed in this piece guaranteed grain match between lid and base. They were cut on the bandsaw before turned with a very fine blade. The base was drilled out and sized to accept an insert of similar wood. The insert was sized to fit a little proud to act as a tenon for the lid. A little extra effort, but a perfect matchup when you're blessed with that special blank.

https://www.aawforum.org/community/media/pangaea-jewelry-box-misc-views.20634/full

 

[Gabriel Hoff]

Best thing I can suggest beyond using straight grained timber is to turn a little step detail at the join that shows the join as a detail but also confuses the eye just enough to hide a slight grain mis-match. It’s a technique I first saw Ray Key use.

I agree the step joint or line at the lid intersection will help with grain alignment. I use a 1/16" parting tool and create the tenon for lid to fit into AFTER I hollow the lid. I essentially have two flat areas one on the lid and one on the base. I keep the base extra long to have enough wood left in order to create the tenon. This really helps in keeping the wood loss to a minimum. Also make the height of your tenon small so you don't have to remove a lot of wood at the joint. Use straight grained wood, this will also help. I had ONE box where I got a perfect grain alignment but it is really rare!

Peroba Rosa Lidded Box

This box is made from Peroba Rosa. I was able to achieve a perfect 360 degree grain match on this box. Size is approx. 2 inches in diameter and 2.25 inches tall. Finished with gloss lacquer.

www.aawforum.org

 

[Don Wattenhofer]

The insert idea is the best bet, but you will still have the parting tool kerf plus the thread offset of .1mm up to 1.6mm to achieve the grain match.
The 1 to 2 twists to close the cover: make the male thread with the 2 or 3 threads, make the female thread large enough to not bottom out the male thread and cut a relief (cut away the start of the thread) on the female thread.
Note that the seasonal movement of the wood may cause future misalignment.

 

[Michael Beswick]

where I got a perfect grain alignment but it is really rare!

This was an early attempt-beginner’s luck!
Thanks to all for the suggestions. Clearly an insert is the closest and I can’t escape the saw kerf effect. But I like the ideas for deceiving the eye

 

[Michael Beswick]

Oops. Multi pic

 

[Doug Rasmussen]

How do the grain matches hold up over time and humidity changes? I have a couple old screw top containers for sets of metal number stamps probably from the 1950's. They're made of very fine grain, white wood, maybe boxwood? I've noticed over the years they don't always tighten at the same position, one even has a pencil marking from a previous owner warning not to over tighten. On a couple occasions it was difficult to unscrew the lids due to normal seasonal distortion even though I make a point never to hard tighten.

One piece of advice on turning design I've tried to follow is make the design attractive in its own right and don't depend on grain for effect. So in the few screw top boxes I've made I avoided wood with wild grain. In a couple I used a different wood with different color..

 

[john lucas]

The box will shift out of alignment seasonally. I've had the change as much as an inch but usually it's just 1/4" or so.

 

[robo hippy]

You want as perfectly straight grain as you can find. I make my recess 3/8 deep, and my tenon 1/4 inch deep. I do relieve the bottom of the tenon a bit. Also, you need to grind off almost half of your cutter, on the top side. You do need to leave enough on the cutter for a full depth thread. This will also allow you some extra room when attempting to cut to full depth. I am one of the few who do it, but I never make boxes over about 1 1/2 inch diameter. The potential for wood movement making it too much and the lid getting stuck is too much of a risk to me.

robo hippy

 

[Don Wattenhofer]

The needle box in Brazilian rose wood measures 1 1/4" diameter X 4 3/4" high with 1 1/16 - 20 thread, the female thread in the base is relieved enough such that it only takes 2 turns to close.

The egg box in white oak burl is in process showing the lid ready to receive the insert then the lid threaded at 20TPI. The thread on the lid will likely be cut back to maybe 3 or 4 threads. The lid has a recess about 2" diameter by 1/4" deep and slightly tapered to compress the glue, then almost immediately the outside of the insert was turned down to 2" diameter and the inside cleaned up.

 

[Michael Beswick]

Many Thanks! I need to practice!