threading small rods?

[boatguy]

Hi guys.

I am a boat builder in need of some direction from those who know.

We build a small hydrofoiling sailing boat which has some control rods to operate parts of the hydrofoils. See my website if you are curious www.fastacraft.com

So to the point, I need to thread the end of a 2.5mm stainless steel rod with a 2.5mm metric thread. I have tried threading 2.4mm stainless steel welding rods with a 2.3mm metric button die only to destroy the die which cost me $60.

If there is a way to this properly? I am prepared to invest in any special equipment as I will need to make a lot of these ongoing.

Can a mini lathe do it? or is there another way or special machine to handle such small threads?

Any advice very welcome, help!

John

[ron]

Hi John
You should be able to do this without resorting to a lathe, I don't know what a button die is but if you use what is known in the UK as a split die open to it's limit with plenty of thread cutting fluid it should cut a clean thread without wrecking the die, then close the die for your final cut, again with cutting fluid. Stainless steel isn't the nicest metal to thread but it is perfectly do able, it might also help if the die and the SS rods are the same diameter although I don't think 0.1 of a mm is going to matter.
Best of luck,
Ron

[circlip]

Would only have reflected what Ron has said if you're looking at cutting the threads although the rod 0.1 less in diameter than the thread could make a difference. The other method to consider depending on "making a lot" is a lot, is to have a look round for a hand operated thread ROLLER. These were used by bicycle manufacturers for rolling threads on the end of wheel spokes. Regards Ian.

Button die is just another term for a standard circular die, but was your original a HSS one of "KNOWN" origin John???

[Tel]

Erm, maybe a stupid question but you are backing it off for chip clearance?

You can't just wind a die on like a nut - 1/2 turn forward, 1/4 turn back usually works for tough material like stainless. Also, use some sort of cutting compound - I favour Trefolex.

[havoc]

Well, if you need 2.5mm thread better get a 2.5mm die. Threading a 2.3 die on 2.5 material is asking for trouble. Certainly in small sizes and with stainless (inox?). Also try chamfering the end making it easier for your die to start the thread.

I must say I haven't seen any M2.3 thread before.

[boatguy]

I did some more searching on the internet and found a few options for the biycle spoke threading machines. Some are just $100 but the pros use one that costs $3200.

I did back off the die when cutting and I used oil for lube as I had no trefolex.

I did not try to cut the 2.5mm rod with the 2.3mm die, I did try to cut the 2.4mm welding rod with a 2.3mm die. Welding rods are some kind of mixture of materials so they may be even harder than 304 stainless steel.

I am yet to get the 2.5mm material and 2.5mm die.

As I said the thread rolling machines seem like they are exactly what I need except that they seem to only cut up to 2.2mm threads. Some talk of guages like 14 & 15 guage which is apparently 1.8mm and 2mm. I did find find a motorbike one that says 9 guage but I have no idea if that is a suitable match for threading the 2.5mm material.

So any idea what 9 guage may be ? approximate metric size?

www.bicycletoolsetc.com/index.cgi?id=93116491&d=single&c=Tools&sc=Wheel-and-Rim&tc=Spoke-Threading-Machines&item_id=HZ-C700

www.britcycle.com/Products/221/22132.htm

And for $3200 www.philwood.com/Spoke%20Machine.htm

[Shawki Shlemon]

I agree with Havoc . When using the die it will cut and also spread the metal , I would be using 2.3 mm rod and 2.5 mm die ,
also using a good cutting fluid and the result will be very satisfactory .The thread will be close to 2.5 mm . Your die will be OK for next time .

[jasonb]

Spoke sizes are based on "STANDARD WIRE GAUGE" sizes. 9g is 3.658mm

2.5mm will fall between 12g (2.642) & 13g (2.337)

If you do go for a rolled thread you cannot roll a M2.5 thread onto 2.5mm rod. As no material is removed by rolling some of the material in the hollows is pushed up to form the tops of the thread. There is a formula for calculating this but its not something I have enough experiance of.

One of the reasons spoke threads are rolled is you do not get a stress raiser where the thread ends and the plain section of rod starts.

If you do stick with split dies make sure they are decent quality HSS ones not carbon steel.

Jason

[weldsol]

Welding rod for stainless could be any type the typical ones are
316 L
347
308 L
309
The worst being 347
Because you are using welding wire / rod it will be partially word hardend due to the drawing process during manufacture

Also using lube oil will try and prevent the die from cutting

Paul

[weldsol]

Sorry should have read WORK HARDEND and not WORD HARDEND
Been out in the workshop and when I came back in someone had moved all the keys on my keyboard
luaP

[GeorgeRay]

Did you really use a button die or was it a normal split die. Button dies look just like a button they have no split in them so are not adjustable and in my experience need very careful handling if they are to cut properly, they also need the right holder to keep them flat and perpendicuar to the workpiece. I personally would not use a button die on stainless. If you are using a button die then the material must be of a smaller diameter than the thread being cut, for 2.5mm thread material of no greater diameter than 2.3mm. Plenty of lubricant and backing off is required although stainless can be a problem. A normal split die will cut a thread on the same nominal size material if you open it out as has been previously said.