Threading a piece if laminated wood

[gerry maddenParticipant @gerrymadden53711]

I’m trying to put a 1.5mm metric form thread on a piece of laminated beech. Using conventional tools, there is too much tearing for my liking.

I “think” what I need is some kind of high-speed cutter mounted on the tool post.

Does anyone know of a device that I could buy to do this, or suggest ways to improve the quality of the cut surfaces using conventional techniques?

(I’m not looking for engineering perfection by the way, just something that most reasonable people would recognise as a thread… if you know what I mean!)

Gerry

[JasonBModerator @jasonb]

Saturate with superglue may work

Dremel in the toolpost will do it with an engraving bit.

Also not that wooden threads are a completely different angle usually closer to 90deg than 60 so that they have some strength.

[Clive Brown 1Participant @clivebrown1]

What do you mean by conventional tools? If carbide inserts, they might not be the most effective. My first choice would be a well sharpened hss form tool with some back rake to give a slicing action.

[FulmenParticipant @fulmen]

I would start by increasing the pitch by a lot.

[Mark RandParticipant @markrand96270]

If that’s a 1.5mm pitch thread, then the OD looks to be in the region of 40mm. That’s a rather fine thread in steel or brass…

Each and all of the above posts are rules to follow. Include all of them and you should get a better result.

[DalboyParticipant @dalboy]

There is a tool for threading wood which is quite expensive for the odd job it is the Simon Hope Threading tool

[JasonBModerator @jasonb]

You have not said what wood the laminations are made up from? You really want a good dense hardwood, beech is often use dfor woodwn screws. Maple or any of the fruit woods would also be OK. Don’t expect pine to take a thread well.

[Speedy Builder5Participant @speedybuilder5]

You are not getting anywhere near the cutting speed for wood.   5,000 -10,000 RPM  ??  Think about the speed of the tip of a circular saw.

Bob

[JasonB]

On JasonB Said:

You have not said what wood the laminations are made up from? You really want a good dense hardwood, beech is often use dfor woodwn screws. Maple or any of the fruit woods would also be OK. Don’t expect pine to take a thread well.

I agree I find the best for threading is lignum vitae, but the chances of finding a piece large enough for what you want is going to be hard as it is no longer available unless it is from salvaged items and then only in small pieces like old bowls balls.

 

I also forgot about what I have and that is these which are for thread cutting in wood. They do need some good eye-hand coordination and best run at 450RPM or a little lower if possible.

The top one is for external threads and the bottom internal threads

[Neil LickfoldParticipant @neillickfold44316]

You want a live threading tool. It is a thread cutting  tool that will go into some form of rotary tool, that is mounted to the lathe.  Ideally, the axis of the tool will align with the helix angle of the thread being cut.

If the wood is soft , then using some thin superglue to harden the wood will help it to be easier to cut. People who make pool cues, use live tooling in their metal lathes for the wooden threads in  the handles of the cues.

You can use a Dremel if you have a mount to hold it in the toolpost. The tools are typically 3mm shank or 1/8 shank carbide, with either a small piece of HSS or Carbide brazed onto the shank. Then shaped to 60 included angle with about a 15deg relief angle angle. Normally it is not extended more than 20mm from the collet.

Some use trim router tools with an adapter to attach to the tool post. They then use tools with a 3/16 shank or 6mm shank. Then they can have the tool extended further from the collet than a 3mm shank tool would be.

[Clive Brown 1Participant @clivebrown1]

The OP said he’s using beech.

[DalboyParticipant @dalboy]

The major problem with threading laminated woods of any type is because the construction of ply (for want of a better word).

Because the wood is in layers with the grain alternating in grain direction as any cutter will be cutting side grain and end grain which causes the effect the OP has on his work. It is best to have the grain running along the lathe bed and not laminated.

[Graham MeekParticipant @grahammeek88282]

Ronseal do a product for treating Wet Rot. It was recommended in MEW for stiffening cardboard for use in Model Dioramas etc. I have used this product for hardening wood and I think it would help with the OP’s problem.

I would put the piece of wood up on end, in a container. Fill the container to a little above the finished thread length and leave it for a few hours to soak up the liquid.

For such a fine pitch you really need to have a rotating cutter. A small Vee-shaped circular saw would be ideal, but you might get away with a Vee-shaped fly cutter. I would have the cutter such that it is cutting on the down stroke.

Failing that you need to use Hydulignum. Wood in a resin, reputedly developed for armour plate on aircraft during the war, but not sure of that little snippet.

Regards

Gray,

[Graham Meek]

On Graham Meek Said:

[…] Failing that you need to use Hydulignum. Wood in a resin, reputedly developed for armour plate on aircraft during the war, but not sure of that little snippet.

That word was new to me, Gray … but here’s a little about it:

https://www.key.aero/forum/historic-aviation/129588-hydulignum-props

MichaelG.

.

P.S. _ if anyone wants a rabbit-hole to explore, try searching espacenet for ‘rotol airscrews’

[Brian WoodParticipant @brianwood45127]

I would make a sleeve in more thread tolerable material like delrin, glue that into place and cut the tread into that if the joint must be a fine thread.

Otherwise, Fulmen’s recommendation of a much coarser pitch thread would be the way to go. We are not told what this is screwing into though.

Brian

[Mark EasingwoodParticipant @markeasingwood33578]

As already said, if your lamina are at 90 degrees to each other the end grain is crumbling away. Either all your Lamina need to run lengthways, or you need to use a piece of solid timber, the interlocking grain should hopefully hold together better.

And as others have said, screw threads in Timber are normally quite coarse, as in the thumb screws used on marking gauges. I think Boxwood was often used, along with Beech and Fruit woods.

I think that the cutters in the Threading boxes, (dies), were a like a “vee” pointed (hand), carving tool. I have a couple ot the Boxes at work, I will have a look tomorrow. A carvers “vee” tool might work, clamped in the tool post, but the edges will be quite delicate.

The Dremel or small router, with suitable cutter may be the best way.

Mark.

[DalboyParticipant @dalboy]

You can also get taps and dies for wood but in limited sizes again it still needs the right type of wood

[Speedy Builder5Participant @speedybuilder5]

This is the stuff you really want – JABROC  see data sheet and uses –

https://www.askmotorsport.fr/pdf/jabroc.pdf

We used to use it for making short life press tools in the aircraft industry (1960s) and I still have a few scraps.  In essence it is compressed beech plywood – probably compressed by 400% or more and obviously the density increases with it.

Suppliers (no connection but you could talk to them perhaps)

Products

[Graham MeekParticipant @grahammeek88282]

Hi Michael,

That little link has brought back a few memories. Rotol had old Wooden props in one of the Hangars on Staverton Airport. Along with ventures into the commercial world like the Dowty Turbo craft which is the forerunner of the Jet Ski.

I very often look for the Blue Winged Dowty emblem on the vintage aircraft.

Hydulignum was used extensively at Rank Xerox for the manufacture of short life Press Tools. We also used a piece to make a special couch top for a Radio Therapy Treatment machine when I worked for the NHS.

Regards

Gray,

 

[Martin KyteParticipant @martinkyte99762]

A lot of wood products come from this neck of the woods. Permali list high density compressed wood for neutron shielding for reactors. This was produced and maybe even developed at PineEnd Ltd on Lydney docks accross the river from Berkeley Power Station. Long gone now but I believe set up to make laminates during the war.

More details here

https://forestofdeanhistory.org.uk/learn-about-the-forest/pine-end-works-lydney/

[DalboyParticipant @dalboy]

There is a product called Cactus juice which requires a vacuum chamber. The wood is placed in the chamber and covered with the cactus juice a vacuum is formed sucking the air out of the wood and once the liquid stops foaming the vacuum is released and the juice is sucked into the wood.

It’s then dried

This can be done in a home workshop as many pen turners use this method.

I was going to do this and have the vacuum pump but did not get the chamber

[VicParticipant @vic]

This might give you some ideas?

https://youtu.be/_NqI6GJ3m38?si=LeXxdbJPqcN5EfaU

 

[Neil LickfoldParticipant @neillickfold44316]

The video shows a multi point threading tool using the headstock.

Here is a video by Bob using  his live threading setup.

At 3min 22 is the start of the live threading.

 

Neil

[SillyOldDufferModerator @sillyoldduffer]

Given that cutting a fine thread in wood is tricky, extra difficult if the wood is laminated, and the result will be a weak easily damaged thread, is it worth considering alternatives?

As already explained by other posters, wood is difficult to thread.  It demands a coarse thread, ideally not cut into a wood that’s soft, liable to split, and expands & shrinks depending on humidity.  Most woods are unsuitable, hence mention of exotics like Lignum Vitae!

Reminds me of this old joke:  a motorist hopelessly lost in the back lanes of deeply agricultural Devon stops to ask a local the way to Lyme Regis.  After a long pause, the local replies “I wouldn’t start from here.”   That sums up my feelings about putting a 1.5mm pitch thread into laminated beech.  The thread is too fine, and the material uncooperative.

Been a few good suggestions that might be counter-productive because this is a laminate.  I have no idea how the resin used to laminate the beech will be affected by a wood-hardener!   Getting complicated, and unless someone knows, will have to be tried to find out.

Gerry hasn’t explained why a 1.5mm pitch thread in wood is needed.  This being a hobby forum, could be a poor choice due to doing something new, or a brilliantly clever way of solving an exotic problem that’s proved difficult in this one detail. Or the motive may be repurposing an available material that’s nearly “good enough”, apart from the thread!  If the idea is to create a strong joint, a 1.5mm thread in laminated wood isn’t good.   Maybe the reason for threading is ease of assembly and disassembly, in which case a fine thread in crumbly wood won’t last.   Gerry may have an entirely different reason.

How about turning a metal collar to fit over the end of the beech rod, and threading the collar?  A metal that’s easy to thread, perhaps Brass if looks matter.   The inside of the collar can be bored to require a force fit onto the beech, lightly splined to resist turning if felt necessary, and glued.   There is no difficulty threading a machinable metal and the thread will be robust.

The collar suggestion is just a guess – I have no idea what Gerry’s requirement is.

Dave

 

 

[bernard towersParticipant @bernardtowers37738]

You could do this or something similar

[Author]

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