Any tips and tricks for threading?

Hey guys,

Once again I've sorta run into another project of mine where precision is important. So I've decided it's time to start using my tools properly, but searching around, there's no real tips on getting a good, straight thread using a die. Loads for taps tho..

I'm trying to thread a ~6mm long, 10mm thread into some mild steel, unfortunately, because of the parts odd shape I can't fit it into my lathe and I don't have a pillar drill to rest the die on. So I'm lost for ideas.

Hopefully most of you have had more experience with this type of thing than me,

Ollie.

... think how goldsmiths fit their 'misshaped' parts to drill precise bores and such - maybe you can embed your part in a cylindrical mould filled with hardening 2K resin, so it's usable in the lathe?

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Odd shaped or thin walled parts often get a fixture cast around them to enable clamping and properly support the piece. There are low-temp, usually reusable metal alloys called fixturing alloys specifically for this purpose. Plastic or plaster might be usable for you for this purpose as well.

Presuming the shaft you wish to thread is clampable, fixture the other side of the piece and turn it concentric by clamping the shaft. Then reverse the piece and thread the shaft as normal on your lathe, either cutting the thread or using the tailstock to suuport and align your die to the workpiece in the headstock.

Hey VDX and Circuits,

I hadn't actually thought of casting a fixing round the part in question. It's only a prototype, so I wasn't going to spend a lot on it, as ive already change the design for 2.0, so i'd've thought an alloy or resin would be a bit much for this first part.

However, I see how plaster would be a cheap and easy casting, but has it been tried in a chuck? Surely it would crack after clamping?

I had another thought too, would some sort of tape wrapped round the part suffice? Or would the jaws just sink too far into the tape?

Ollie.

Plaster is probably too brittle to clamp mild steel for this purpose. I have low temp moldable plastic (brand name instamorph) and fixturing alloy on hand I'd be using. Given the part is metal, some resin should work for you, then simply heat the part to burn or slough it off when done. I doubt you'll be able to get tape concentric enough for good threads, though.

Use a 4 jaw and an indicator? I got both lyin round

Hello,

Could you post a picture of the part in question?

Regards,

Brian


Ollie Wrote:
-------------------------------------------------------
> Hey guys,
>
> Once again I've sorta run into another project of
> mine where precision is important. So I've decided
> it's time to start using my tools properly, but
> searching around, there's no real tips on getting
> a good, straight thread using a die. Loads for
> taps tho..
>
> I'm trying to thread a ~6mm long, 10mm thread into
> some mild steel, unfortunately, because of the
> parts odd shape I can't fit it into my lathe and I
> don't have a pillar drill to rest the die on. So
> I'm lost for ideas.
>
> Hopefully most of you have had more experience
> with this type of thing than me,
>
> Ollie.

Hey Brian,

Not tonight unfortunately, not near my scanner or a camera atm, in the morning I can but until then lemme see if I can describe it to u.

It's basically a 5cm long cylinder, with each end having a larger diameter than the middle. The end I need to thread is 10mm Dia. And is 6mm long, all of that needs to be threaded correctly with 10mm x1mm pitch, 60 degree thread. There is a hole running though the length of the part with a Dia. Of 5mm, the middle length of the part is say, 35mm long, Dia 7mm, then the bottom is ~10mm long with Dia. 8mm.

Sorry if that's confusing, but best I could do right now.

Ollie.

Hello,

Ok, I think I get a picture of what it looks like. It sounds like a great candidate for a lathe. Why won't it fit in your lathe?

Regards,

Brian


Ollie Wrote:
-------------------------------------------------------
> Hey Brian,
>
> Not tonight unfortunately, not near my scanner or
> a camera atm, in the morning I can but until then
> lemme see if I can describe it to u.
>
> It's basically a 5cm long cylinder, with each end
> having a larger diameter than the middle. The end
> I need to thread is 10mm Dia. And is 6mm long, all
> of that needs to be threaded correctly with 10mm
> x1mm pitch, 60 degree thread. There is a hole
> running though the length of the part with a Dia.
> Of 5mm, the middle length of the part is say, 35mm
> long, Dia 7mm, then the bottom is ~10mm long with
> Dia. 8mm.
>
> Sorry if that's confusing, but best I could do
> right now.
>
> Ollie.

Because my jaws are frankly too long to get a decent, full length grip on the part, because of the ends being later than the middle. So I'm not too sure how I could chuck the part.

Ollie.

try putting the part into a chuck centre and putting the die and rack against the jaws and turn the die as you advance the chuck.

that;s how we were taught in tradeschool.

Mount it between centers, on the lathe, then thread it.

Regards,

Brian

For anything bigger than the part I'm workin on Brian, I'd agree with yu, but the walls are too thin in my opinion for between centers. Although Mech has a good point, cheers, I'll give it a go

Ollie.

Hello,

If the walls are too thin, maybe the center should have been drilled out last, after all of the high-stress machining operations are finished?

Regards,

Brian


Ollie Wrote:
-------------------------------------------------------
> For anything bigger than the part I'm workin on
> Brian, I'd agree with yu, but the walls are too
> thin in my opinion for between centers. Although
> Mech has a good point, cheers, I'll give it a go
>
>
> Ollie.

Probably, yeah. But I rush into things....

Ollie.