Repairing a stripped milling vice

[Keith MathesonParticipant @keithmatheson47708]

Hi

I have been given a broken milling vice as I do not have one. It is 6inches and although a bit on the big size for my 8inch by 32 table ( amadeal AMA30 ) it's seems to be a good solid piece of kit. However, the threaded nut inside has stripped. I'm looking at options. One is to buy a chunk of brass? Bronze? Leaded bronze? And make /cut the thread I need. ( as well as the boss etc)This seems quite a daunting task to be honest. Could I just buy a suitable nut and then just modify/ make the boss? I then saw on eBay trapezoidal rod and nuts. Maybe I could replace the whole rod, modify the nut so it sits at the right height and go that route. I am trying to tread a path between a beginner trying to push his skills (a bit ), a new hobbyist who wants to just get on with some milling, and someone who has run out of money to throw at his workshop for a while! ( so don't say just buy a new one! Any wise words will be gratefully received. Maybe some one will recognise the vice if I can manage to post the photos.

Thanks in advance

Keith MM

[Keith MathesonParticipant @keithmatheson47708]

[jason udallParticipant @jasonudall57142]

Trapezoidal thread isn’t magic..it is basically a truncated ‘standard’ thread…
..infact many cheap G clamps use metric threads.

For a one off taps and dies for what are called acme threads (closer to square section than trapezoidal) are probably a waste.

Frankly using metric ( or whitworh or unc or….) conventional screw threads will suffice until you feel they don’t
.

[jason udallParticipant @jasonudall57142]

What I am basically saying is get some studding as big as fits..make nut to couple with slide..
..then as time/skill/tooling/frustration( with less than gold standard job)/pride dictate replace with nicer /better job

[Keith MathesonParticipant @keithmatheson47708]

Wow, thanks Jason, what a great idea. Eminently doable and as you say I can easily go back at a later date and do a more elegant job when time and skills allow. This way I can have a working milling vice by the weekend!

Many thanks

Keith mm

[John ReeseParticipant @johnreese12848]

1. Use a bearing bronze. Brass will not last.

2. Single point the threads on the lathe. Not that difficult and good experrience. Tooling cost is negligible.

3. Make a short lead in diameter that matches the OD of the screw. When the point of the tool just marks that diameter it is time to start testing the fit using the screw as a gauge.

Years ago on my first day working in a machine shop, the nut for the top slide stripped out on the lathe I was using. As I recall it took about 4 hr. to reverse engineer the nut, scrounge for material, and finally make the part.

To save time you might try silver soldering a bronze sleeve into the existing nut, then threading it.

John

[Harry WilkesParticipant @harrywilkes58467]

Glad this thread popped up only last week I was given a decent vice it's got a slight bend in the screw thread dont know if I could straighten it after all if it's broke you cant brake it or have a go at make a new screw ! It looks to be Acme form M14 x 3 ? any comments / suggestions

Thanks H

[Brian WoodParticipant @brianwood45127]

Hello Harry,

You can easily straighten that. Make a couple of wooden Vee blocks, rest the screw thread across them on a solid floor with the bend piece uppermost and using a decent weight hammer with a block of wood between the screw and the thread give it a belt. then check to see if it has straightened or bent the other way and repeat the process with suitable adjusted hammering until it is right.

I was able to correct a bent vertical leadscrew on a mill that way, some idiot had put a rope on it to pull the machine away from a wall, and more recently a 3/4 inch diameter shaft in a gearbox to within a 2-3 thou run out.

Regards Brian

[Michael GilliganParticipant @michaelgilligan61133]

Posted by jason udall on 07/03/2016 20:08:32:

Frankly […] will suffice until you feel they don't

.

Very succinct, Jason.

Worth quoting as general philosophy.

MichaelG.

[jason udallParticipant @jasonudall57142]

Indeed Michael

As I get older. I encounter more and more instances of my ” this will get it working long enough” bodges…that 30 years later are still working better than factory original.
Not boasting but observing with wry smile.
Firm believer of function first.
Form is important too, just not first. And certainly not only. ( see most “designer” production for ref. )

Not EVERY job worth doing is worth doing well.

[jason udallParticipant @jasonudall57142]

And..me succinct? ..vicious rumour

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