Help - Machining slim rod on the lathe

[DaveH]

Usually they are called 4 Jaw Self Centering Chucks

DaveH

[Wongster]

Steve, yes it does look like the one in the pic.

[Brian]

As the Irishman said if I was going there i would not start from here.

But if I HAD to try this job
1/ start with 4 mm rod.

2/ drill and tap the thread first then slowly take the od down.

3/ use a collet and keep the work close

4/if a collet is not available make a split bush and mark its position in the chuck

5/ the screws are probably only to retain the wheels so could be smaller.

brian.

[Wongster]

Hello Brian,

I was thinking about the same process except the part using collet or split bush. I was thinking of using the 4 jaw independent chuck.

I'll ask that guy if smaller screws will do.

Thanks for your input.

Regards,
Wong

[Brian]

(03-15-2013, 06:40 AM)Wongster Wrote: Hello Brian,

I was thinking about the same process except the part using collet or split bush. I was thinking of using the 4 jaw independent chuck.

I'll ask that guy if smaller screws will do.

Thanks for your input.

Regards,
Wong

further thought. having taped the thread maybe pluging it with a stud will give extra support while the OD is machined

Brian.

[Wongster]

(03-15-2013, 03:14 PM)Brian Wrote: further thought. having taped the thread maybe pluging it with a stud will give extra support while the OD is machined

Brian.

I was thinking about the off the shelve axle he brought to me with the same dimension but shorter. The request then was to increase the length of the 3mm dia section at both ends. The M2.5 holes were in the axle when he bought it. I used a tiny boring tool bought thru an Irish friend from UK to do the turning. Seemed to work ok. But I did turn down very little amount at a time with the tiny boring tool that has very sharp edge.

I think your suggestion of putting in a stud or screw while turning is a great idea; lesser chance of a screw up.

I'll be off to Israel for 10 days from Monday. Will order some 4mm SS rods when I get back.

Regards,
Wong

[Wongster]

Hi guys,

I bought a length of SS rod of the right diameter (4mm). All work well except that I broke 2 M2 taps while trying to tap the 2 holes. The first can be salvage as I was already at the right depth when the tap snapped. The 2nd tap for the 2nd hole snapped at just a short distance in and refuse to come out. I was hiding the tap in the tailstock with a drill chuck.

Before I start on a new piece with new taps, any advice for this tap breaking newbie? I've so far only broke a tap (M3 I believe) in the past.

Regards,
Wong

[Mayhem]

Small taps are always an issue and I sometimes drill the hole a little larger where possible. Ensuring that the tap is perfectly straight is also essential. I would go no more than a half turn before backing off. Cutting fluid always helps.

I've not tapped SS before but I have read that you may be better off buying s spiral flute tap rather than a straight flute one. I'd wait for someone with experience in SS first though...

[TomG]

What type of stainless did you buy? Some types, like 304 are very difficult to tap, but 303 is very easy. Make sure you have a good quality tap (ground not cut) and hold it in a tap wrench, not a drill chuck. You can make sure it starts straight by supporting your tap wrench with a center in the tailstock. You can get or make spring loaded centers for just that purpose. Be sure to use a tapping fluid recommended for stainless.

Tom

[stevec]

(04-01-2013, 03:28 AM)Wongster Wrote: I was hiding the tap in the tailstock with a drill chuck.
Wong

I was going to point out the same thing that Tom mentioned.
I have held taps rigidly both with tailstock chuck and modified tap wrench and under power too but not that small and especially not in stainless.
Steve.