gripping brass tube

[jarndice]

I am in the process of tapping a 2.5mm thread into a 3mm brass tube, I began by putting in a pilot 2,2mm thread which was ok but now the tube wants to turn as I feed in the 2.5 tap, I could of course put the tube in the vise but it would probably crush it and would almost certainly mark it, If I had a 2.00mm rod that would allow me to grip it but the marks would be plain to see. I realise that there is a blindingly obvious solution but unless the answer is six feet high in flashing neon I will miss it, any not too expensive advice would be appriecated.shaun

[Tankbear]

How about cutting the tube longer than you need by 20mm, then put that end in the vice squashing flat if need be for a good grip. Tap you bit you want then cut off the extra squashed bit.

Ian.

[PainlessWolf]

Good Afternoon,
Something from the automotive world could assist you here. I use a 6 dollar pair of spark plug boot pliers, (the kind with the rubber pads designed to grip the spark plug wire's rubber boot and remove it from a spark plug without damaging it), to securely grip anything I am working on that I do not want to mar or damage. Hope this is of use.
regards,
Painless

[jarndice]

Yes yes Tankbear but where are the flashing neon lights? You see what I mean about the blindingly obvious, totally passed me by. Thank you, you have just gained hero status. shaun

[dgsselkirk]

How about cutting the tube longer than you need by 20mm, then put that end in the vice squashing flat if need be for a good grip. Tap you bit you want then cut off the extra squashed bit.

Ian.

Just to add to Tankbears idea, instead of putting in a vise and taking the chance of crushing to much of it, if I read right what about drilling a hole through the extra length and putting a rod through it so you have a "T" you could crank on the die?

Just a thought...

[jarndice]

Hallo Painless old friend, I just had a look in the garage and the grips you suggest are not going to close down to 2.5/3.5mm but you started a train of thought I shall pursue in the morning that is a pair of pipe grips, having first wrapped half a mile of masking/duck tape around the tube. Tankbears thought has I belatedly realised got in my case a drawback, my fault, I failed to explain that I would be putting a thread in both ends. Onwards and upwards. Keep warm and thank you. shaun

[ALPHA]

Hallo Painless old friend, I just had a look in the garage and the grips you suggest are not going to close down to 2.5/3.5mm but you started a train of thought I shall pursue in the morning that is a pair of pipe grips, having first wrapped half a mile of masking/duck tape around the tube. Tankbears thought has I belatedly realised got in my case a drawback, my fault, I failed to explain that I would be putting a thread in both ends. Onwards and upwards. Keep warm and thank you. shaun

Just to add to Tankbears idea, instead of putting in a vise and taking the chance of crushing to much of it, if I read right what about drilling a hole through the extra length and putting a rod through it so you have a "T" you could crank on the die?

Just a thought...

Just not to be redundant... these are the two methods I would have used...add in also .. if you have one... a three point pipe cutter vise ... a lot of larger model vises have them built in... usually under the main mandrel.. the clamping faces can be padded with duct tape or something

Also if you are going to tap both ends... tap one side first... screw it to whatever you are going to use it on... then tap the other end

BUT MOST DEFINITELY ... MAKE SURE YOU ARE HAVING FUN DOING IT

ALPHA

[Saracen]

Sounds like you need a collet of some sort. That would clamp as a circle and be less likely to crush it.

You could try a pin vice, or even a drill chuck, though they may end up making the end triangular.

Adrian.

[Panther Ausf G]

Anything gripping the outside of your tube is likely to mark it.
The drill a cross hole through is a better suggestion.
Alternatively you could put a close fit solid brass bar up the end and sweat it in your tube, that can be griped in a vice and when you have finished just heat up to release it again.