Turning tools - form tool design needed from experts

[michiganbuck]

I've a feeling you are right dian, ..............and IMHO should have been drawn up so from the start.

Might be a threaded nose piece welded or glued in place.

 

[Billtodd]

Yes I agree lack of space is a serious problem.

If I really, really had to make it in one piece, then I'd look to make a pivoting cutter bar on the end of the largest boring bar i could fit into the bore with clearance for swarf . Then couple the pivoting bar via a linkage to a tracing mechanism .

Hi Limy Sami:
Did you factor in the amount of stickout for the boring tool and how skinny it has to be to reach the small end without crashing into the sidewall of the parallel part of the bore.
It's not looking promising.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

 

[gbent]

Forged, possibly deep drawn. Think high pressure oxygen bottle. Looks like WMD.

 

[DDoug]

Forged, possibly deep drawn. Think high pressure oxygen bottle. Looks like WMD.

Yup, which way are these things going to be pointed OP ?

 

[ChipSplitter]

Forged, possibly deep drawn. Think high pressure oxygen bottle. Looks like WMD.

Can't believe it wasn't noticed until the second page.

It's shockingly obvious what it is.

 

[Limy Sami]

Can't believe it wasn't noticed until the second page.

It's shockingly obvious what it is.

there ya go - somebody else for your Mr Trump to p[ick a fight with.

 

[DDoug]

there ya go - somebody else for your Mr Trump to p[ick a fight with.

Huh ?

I believe Mr. trump is trying to get the USofA out of endless wars in the middle east.

 

[Limy Sami]

There's difference between a fight and a war.

 

[johansen]

internal volume and dimentions work out:

Royal Ordnance L9 - Wikipedia

 

[implmex]

Hi All:
A number of you have implied this might be ordnance of some sort.
While I agree the shape is reminiscent of a projectile, I can find no evidence from what little the OP has shown to confirm this is the case.

We've also seen a single photo of a manual lathe, and the presumption is that he intends to use this machine to make these.

So unless India's weapons manufacturing facilities are still in the stone age, I'm having a hard time believing the Indian Army's procurement department is having ordnance built in such crude facilities.
If someone needed a gazillion antitank shells or whatever, I have a very hard time believing they'd try to turn them from EN 24 bar stock on an antique manual lathe...the stupidity of such a process plan boggles the mind.

So I doubt there's anything sinister in the project, and if the OP ever bothers to respond maybe he can reassure us.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

 

[Limy Sami]

Okay, as it's not ordnance, it must be a big dildo.

Dunno which is more scary?

 

[johansen]

So unless India's [...] still in the stone age, I'm having a hard time believing the Indian Army's [...] stupidity of such a process plan boggles the mind.

you should visit India sometime.

i mean no offense to OP.

 

[cndu]

HI, ALL, Thanks for your valuable inputs.

And for some of you who think it is a WMD, To assure you, it is not. This is for an R&D project for a company called as BHEL (Google for more info). The purpose and other things can't be told.. (signed an NDA).

So, now, the machining part, I am planning to use a cutter which will have 3 cutting edges with profile as per drawing. The Cutter specs are "REPLACEABLE INSERT CUTTER" with OD 135 X 900 WL X MT-5

So, let me know this thing works.

And, for anyone else who still have some ordinance related doubts, I would let you know that those things are only done by companies such as TATA, RELIANCE, GODREJ and some other multi-million dollar companies.

Thanks & Regards
bhargav

 

[eKretz]

That is going to be a right bastard to machine in one piece. Saw this earlier and didn't reply, but was thinking "should have been forged." Two piece weldment would be easier too. Getting that done with a form cutter all the way down the hole is going to be a pain... The boring bar is a no-go IMO. WAY too much stickout, especially working so far down a hole it will be impossible to see what's going on. That would be about like trying to bore it with a wet noodle. If forging or welding are off the table, the form tool is about the only way I can think of that might stand a chance.

 

[implmex]

Hi again Bhargav:
You wrote:
The Cutter specs are "REPLACEABLE INSERT CUTTER" with OD 135 X 900 WL X MT-5

This implies you want to hold this form reamer in the tailstock of your manual lathe.
DON'T DO THAT!!

It's a bad idea because you have no hope of resisting the torque this thing is going to put on a Morse taper 5 socket and a tailstock barrel antirotation key...You need much better than that in my opinion or you'll just wreck the lathe when the key shears (if you don't twist off the MT5 tang first).

You need at a minimum, to take the compound slide off the lathe and build a toolpost that will clamp a reamer shank very solidly directly to the cross slide.
You need to lock the cross slide too, or even take it off and bolt the toolholder directly to the saddle so you only have the one single axis of movement and can transfer the forces through as few sliding joints as possible.
This thing will be HEAVY and will droop significantly just from its own weight.
You may want to make the bar twice as long as needed and clamp it in the middle so the back half can be a counterweight to the front half, and keep the lathe saddle from lifting in the back.
If you make it hollow and plumb it for high pressure coolant, you can reduce the weight but also use the center hole to evacuate the chips, almost like a gundrill.

You can also benefit from putting three rollers into the reamer head that can be tensioned against the straight part of the bore almost like a steady rest, to keep everything centered without having to make it a very close sliding fit.
How much work that adds to building the cutter head depends on how fancy you want to make it.

So, your new plan is going to have to be to step drill the nosecone profile, and then start reaming at low RPM until the reamer is to depth.
I recommended 3 flute left hand spiral right hand cut for a reason...the worst thing you can have happen is that the reamer grabs and tries to screw it's way into the partially finished bore when you put pressure on it to make it cut.
Left hand spiral,right hand cut resists that tendency and three flutes tends to keep the reamer head centered in the bore.

Good luck with it...it's a difficult project.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

 

[DDoug]

HI, ALL, Thanks for your valuable inputs.

And for some of you who think it is a WMD, To assure you, it is not. This is for an R&D project for a company called as BHEL (Google for more info). The purpose and other things can't be told.. (signed an NDA).

So, now, the machining part, I am planning to use a cutter which will have 3 cutting edges with profile as per drawing. The Cutter specs are "REPLACEABLE INSERT CUTTER" with OD 135 X 900 WL X MT-5

So, let me know this thing works.

And, for anyone else who still have some ordinance related doubts, I would let you know that those things are only done by companies such as TATA, RELIANCE, GODREJ and some other multi-million dollar companies.

Thanks & Regards
bhargav

You tell us, that you can't tell us what it's for, but to trust us it's not for ITAR....

And then the part in red....NO the likes of your small company could also be a subcontractor to the above listed companies, so there is a "Real & present danger".

 

[kenton]

That is going to be a right bastard to machine in one piece. Saw this earlier and didn't reply, but was thinking "should have been forged." Two piece weldment would be easier too. Getting that done with a form cutter all the way down the hole is going to be a pain... The boring bar is a no-go IMO. WAY too much stickout, especially working so far down a hole it will be impossible to see what's going on. That would be about like trying to bore it with a wet noodle. If forging or welding are off the table, the form tool is about the only way I can think of that might stand a chance.

I have bored parts with similar, and longer length to diameter ratios and yes they are a right bastard but they are doable. Using sharp positive cutting geometry inserts like those intended of aluminum and small nose radii you can get away with some weird stuff if you turn slow enough. Granted a CNC lathe would be about required for this part.

I agree that making this out of 2 threaded pieces would be the way to go if it is an option, but in prototyping sometimes the designer isn't interested in making something easy to machine. Especially if you already said you could make it as is.

 

[wesg]

... a company called as BHEL ... (signed an NDA).

bhargav

Probably shouldn't have told us that either.

As for concerns about ordnance, consider who they've recently been having trouble with. Concerns me very little.

And yeah, that looks like an absolute mother to machine. The nose is a curve, spec'd by the incremented diameters? And not a series of straight steps? hard to tell from the pic's.

 

[cndu]

Actually, for a small quantity of 8 No's. Closed Die Forging would be expensive, We haven't thought of the option to weld, may be we can try one if our customer permits.

 

[cndu]

Hi cndu:
This is going to be very hard to form turn; you have a huge surface area to accommodate and a surface finish requirement that will be hard to achieve without excellent chip control.
You have to form ream a depth of 235 mm and the torque on any form reamer will be huge.
Also you have to find a way to rough the shape first, so you can take the minimum necessary with the reamer.
If you try to single point bore it you are reaching in a diameter to depth ratio of almost 10:1 once you take into account that you cannot have a boring bar that's more than half the bore diameter (to give clearance at the back side of the bar when you're roughing the smallest diameters right at the tip of the form.)

So the only realistic way forward on a lathe is to step drill the shape as close as you dare to go, and then make a reamer with interrupted flutes (to break up the cut as much as possible) and feed it in very gently in a manner similar to how a chamber is reamed for a rifle barrel.
To guide the form reamer first you need to bore the straight section accurately to 135mm (5.314") diameter and 655 mm (25.78") deep.
That's already quite a challenge unless you have a really stout lathe with a nice rigid De-Vi or equivalent boring bar

Ideally you will have high pressure oil coolant through the tool and a big escape channel for the chips otherwise you'll destroy the finish inside the bore from chips dragging.

These will be slow to form ream and you are going to need a very powerful lathe...I think 50 horsepower is a nice number, but I haven't done any calculations so that's just a guess.

Alternatively you can find someone with a really big sinker EDM...this would be an easy job for a vendor with the right equipment.

On a last note; the easy way to guarantee the volume is correct, is to make everything a bit deeper, fill it with water, measure your difference from the water level to the open end of the bore and then turn it down to the correct length.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

Thanks Marcus, that was a very valuable input, which we haven't thought off. Will definitely consider long bar and clamping to a saddle.

"3 Flute Left Hand Spiral Right Hand Cut FORM REAMER" ? Can you guide me more.. I mean like instead of a form tool should i get a form reamer?