Threaded Boxes

[tekno.mage]

Hi everyone, been playing with my thread-cutting jig and made some boxes with threaded lids...

First, some from native timbers in Hawthorn, yew & hazel.

Next some decorated with gilt cream in rings on the lids in damson, purpleheart and gonco alves

Then I got out the epoxy and metal powders and added coloured rings to the lids These are in paduak, hawthorn and anjan

Then a couple or larger ones in some amazing pieces of hedgerow hawthorn -

And finally, a couple in a completely different style using up offcuts of different woods. The larger one is anjan with purpleheart and the smaller is pale zebrano with darker zebrano. I'd like to develop this style so both top & base are threaded - but for these experiments, there wasn't enough wood in the offcuts I used so the bases are glued on.

They are all finished in Osmo oil and Renaissance wax. All but the last two had the oil coats buffed using the Chestnut system.

Your comments would be welcome.

tekno.mage

 

[CHJ]

Some neat little boxes there, I guess you are really getting to grips with the threading jig.

How are you managing the grain alignment, I assume you are cleaning up one or other of the ends to achieve the rotational alignment after the threading.

 

[tekno.mage]

I'm not having too many problems with aligning the grain as most of the boxes have a lid deep enough to allow more female thread than is strictly necessary - which means it's easy to trim back the shoulder on the male threaded flange to align the grain.

Some of my earlier attempts didn't use this method and meant I had to trim thread from the end of the male flange to achieve grain alignment - which in the worst case left the flange with only 1 1/2 turns of threading.

Actually, the main problem I've had so far is with concentricity. I think some of this may have been caused by preparing the boxes to be threaded in batches - so some were left for a week or so and moved and went very slightly oval before the threads were cut (depite being rough hollowed and left for a year before being prepared for threading!) This problem doesn't seem to occur with very dry wood (kiln dried bits, or very old offcuts.)

I've also found that you have to be very methodical about marking where chuck jaw one lines up on the parts so when you insert them in the jig they are correct.

The other thing I am still working out is cutting the threads "by the numbers" as my jig has a proper cross-slide with scales it should be possible to cut the female thread, then mount the male part and move the jig a set amount (current experiments make this about 17.5mm for a 19mm cutter) rather than setting the cutter by eye and adding the .859mm thread depth.

I've also discovered that the difference in size between the hole in the female part and the spigot of the male part is nothing like as critical as I'd thought it would be and tolerances of .5mm are quite acceptable and result in working threads.

There is a lot more accurate measurement needed using the jig than when chasing by hand, but using the jig does means I'm able to cut good threads in woods that are unsuitable for hand chasing.

tekno.mage

 

[gasmansteve]

Cracking boxes there TM ! Love to have a go at threading. At a recent demo at our club the demonstrator implied that Boxwood is really the only/best wood to use for threads nice to see you`ve proved him wrong, maybe stuff like oak or ash have the wrong grain structure for a good thread??
Steve

 

[NikNak]

Stunning.... i too love making little boxes, in fact cant make enough of them as they all get snapped up by the women at work.

What sort of dimensions are they..?

As my lathe is only a 'starter' one, i'm stuck with either using the cheat method of using the brass threaded inserts or the simple tenon type fit...


Thanks for sharing them with us.



Nick

 

[tekno.mage]

Hi Steve,

If you want to hand chase threads you really need to use hard fine-grained woods as the process of hand-chasing is a scraping one. Boxwood works very well, but is expensive and hard to find. I've found other hard UK woods will work if you can find them. Hawthorn and blackthorn are hard and fine grained, as are lilac and holly. Probably the cheapest and most easily available practise wood for hand chasing is yew.

If you cut threads using a rotating cutter like my jig does, this opens upother woods to the process as you can see from my pics

My current experiments are on ash and sycamore (which are the woods I like to use for decorating and colouring). I know I can cut a reasonable thread on ash - but am unsure of how long it will last in use. I usually give ash a coat of diluted sanding sealer in the areas to be threaded before actually cutting the threads.

In theory, the cutter should put a thread in any wood - but I doubt that anything very soft or spalted will work well - the thread might work, but bits will probably crumble away and it would look bad.

Also, with really coarse-grained woods like oak, a coarser thread would be better. Mine are currently 16 tpi as that is the thread on the leadscrew on my jig. I will probably make another leadscrew assembly up to do 8 tpi to make larger, coarser threads at some point.

tekno.mage

 

[Paul.J]

Nice looking boxes TM
Re- using softer woods.Could you not put an harder type wood insert on the inner of the softer wood to cut the threads,one that would match of course when you see it opened :?:
Or would it be too fiddly to do :?:

 

[tekno.mage]

The smallest one is approx 45mm diameter and 65mm high. The shorter, squatter ones are approx 60mm diameter by 45mm. The tall hawthorn ones are approx 60mm x 100mm.

The ones with contrasting top and base are 65mm x 90mm and 50mm x 60mm.

Are you sure you couldn't make a thread-cutting jig to fit on your "starter" lathe? My jig could be mounted on most lathes with flat bed bars by using spacer blocks to get the centre height correct - and I'm sure I could adapt it to fit a lathe with round bed bars (or even a single round bed bar) if I had to!

Check out my post on building the jig <a>https://www.ukworkshop.co.uk/forums/prototype-thread-cutting-jig-t43205.html</a>

tekno.mage

 

[tekno.mage]

Re- using softer woods.Could you not put an harder type wood insert on the inner of the softer wood to cut the threads,one that would match of course when you see it opened :?:
Or would it be too fiddly to do :?:

Yes - you could use a harder wood as inserts for the threads. It's something I'm considering for use with soft spalted woods as I have some rather attractive spalted hawthorn and hazel that really are too punky for a good thread.

tekno.mage

 

[gasmansteve]

Like the jig set up TM. The guy at our club just did it by hand. If I did a lot of threading your jig is the way to go
Steve

 

[shedhead]

You have made such a good job of cutting the threads. I bought a jig like yours from Ebay. As of yet I have not used it, had other things to do first.
How easy did you find it to work. When I bought the jig it said that it comes with a Instructional DVD. This was meant to follow later, but sadly a good few months down the line I am still waiting to receive the DVD. I contacted the seller and he replied that it would be made soon!!!!!!!!!!!!!!!
Have you got the DVD or are you still waiting.
Dermot.

 

[tekno.mage]

Hi Dermot,

I didn't buy my jig from Ebay - I built it myself. (I'm still in the process of writing instructions for it as well!!!)

My jig is basically fairly easy to use and my earliest attempts cut good working threads on test bits of wood. Things get a bit harder when you want to finesse things or make using the jig faster and more repeatable.

I'd hassle your ebay seller for that DVD or at very least some written instructions including such things like the depth of thread to cut for your particular leadscrew size. (If your leadscrew is 16tpi, the depth of cut is 0.859mm, BTW, as that's the same as mine.)

tekno.mage

 

[CHJ]

....... I usually give ash a coat of diluted sanding sealer in the areas to be threaded before actually cutting the threads.
......tekno.mage

Have you tried applying Thin CA? I find it works well for strengthening weak endgrain or soft spots I'm trying to hold fine detail on.

 

[Lightweeder]

Full of admiration tekno - lovely boxes but, unfortunately, the whole process is a bit beyond me cerebrally

 

[Jonzjob]

Madge, that is a lovely collection of boxes! I have been think for ages about thread cutting and I have got as far as the Axminster set that cuts about 3 threads/foot, well a bit finer than that but far too course for boxes.

Looking at you rig, a fantastic bit of engineering by the way!, how did you source the X/Y slide? Is it from a metalwork lathe?

Thank you for posting both the photos and the info on the cutter

 

[tekno.mage]

Looking at you rig, a fantastic bit of engineering by the way!, how did you source the X/Y slide? Is it from a metalwork lathe?

The x-y cross slide was a very lucky ebay win. I think it might have been from a small mill. I won it for £35.00 - and it was local to me

BUT - you could (as I was intending) use another length of the leadscrew threaded bar to make your own slide for across the lathe bed.

The main downside of the jig I've made is the weight. It takes two people to mount it on the lathe - one to hold the jig and the other to locate the wooden block correctly between the bed bars before sliding the whole jig into place and doing up the bolts. This is why I batch process any threading - so there are several items prepared and ready to go.

One advantage of using an engineering cross slide (apart from the accurate scales) is that by mounting an end-mill milling cutter in the lathe instead of the thread cutter, you can use it to mill holes and slots in box lids (held in the chuck on the jig) to accept wooden inserts for decoration. Milling a hole requires less thickness in the top of the lid than a Forstener bit requires as an end mill has no point in the middle, so I can accurately mill a hole or slot 0.5mm or 1mm deep - and the milling cutter leaves lovely clean edges.

tekno.mage

 

[stevebuk]

Looking at you rig, a fantastic bit of engineering by the way!, how did you source the X/Y slide? Is it from a metalwork lathe?

Thank you for posting both the photos and the info on the cutter

Have i missed the cutting rig pics, beautiful boxes madge, really envious now. :lol: :lol:

 

[Jonzjob]

Oh dear Steve? Do try to keep up!


https://www.ukworkshop.co.uk/forums/prot ... 43205.html

If you have a look at www.teknomage.co.uk/photos/threads/diagram.pdf there is a diagram of the kit! Very impressive!!

Great stuff Madge!

 

[dickm]

Those are super boxes! I've done one or two small ones using thread chasers, and sometimes they work, sometimes they don't. But there's an X-Y table on my Mystro - now feel inspired to rig up something similar to your setup 8) to make things properly reproducible.

 

[tekno.mage]

Do try using the X-Y slide on your Mystro, Dick - using a jig definitely takes the risk factor out of threading compared to hand-chasing, apart from making threading available for a much wider variety of woods.

My own experiences with hand chasing were variable. Test threads were easy to chase, but every time I tried to hand chase on a "real" project, especially when using a nicely figured piece of wood, my chasing technique always seemed to go pear shaped!!!

I'm about to try cutting threads on a couple of ash boxes and some elm & walnut ones today - will report back with results.

tekno.mage