Creating a Hub for a D-shaft 6

[Helepolis]

Hi all,

At first it seemed like an easy thing to do, but not so sure now .

I need to assemble a Hub on a D-shaft of 15mm Dia., the Hub already has a hole of 10mm Dia. so it needs to be enlarged and create the "shelf".

.
Can this be done without creating large radius (anything over R1 mm) at the seem between the hole and the "shelf"?

 

[Artisi]

What is a D shaft and what is a shelf?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[AidanMc]

Broaching? EDM (wire or sinker)?

Aidan McAllister
Metallurgical Engineer

 

[btrueblood]

...file, whittling knife, chemical etching, waterjet, laser, ...

 

[greg2835]

Wire EDM

 

[Tmoose]

I was surprised when Google did not pull up dozens of hits for D drive, D bore, or something.
Are the torque requirement so great a set screw and a sprocket with a 15 mm D bore would not work?
Or, must the sprocket slide?

At some point I'd consider afixing a plate or bar to the side of the sprocket to D-ify the bore.

5 down 5 to go.

 

[Helepolis]

What is a D shaft and what is a shelf?

Sorry for the terminology, not a native speaker.
by "shelf" i meant the flat feature in the bore.

Are the torque requirement so great a set screw and a sprocket with a 15 mm D bore would not work?
Or, must the sprocket slide?

The torque is the issue.

If the hub is 23mm thick, what is the most cost effective method from what you've suggested?
The wire EDM sounds like the best option for its accuracy but looks expensive.

 

[Nescius]

How many hubs need machined? Just one?
What equipment is at your disposal?
What material is the hub made of? Steel? How hard?

A file has been mentioned, as have some very sophisticated techniques. They are vastly different, but each could actually be the perfect tool, depending on the circumstances.

At some point I'd consider afixing a plate or bar to the side of the sprocket to D-ify the bore.

Deify the bore! All hail Bore!

 

[1gibson]

If it's technically acceptable and easier/possible with your current equipment, could you go full diameter bore on the hub, add a keyway and rectangular key, almost like a half key? The inner face of the key then goes against the flat of the shaft. If you permanently install the key into the hub (press fit and/or tack weld) then you're as intended fit/form/function.

Does it need to be "done right" or do you just need it to work?

 

[Helepolis]

How many hubs need machined? Just one?
What equipment is at your disposal?
What material is the hub made of? Steel? How hard?

I need to machine 30 hubs.
I'm outsourcing the job.
The hub is Hardened steel (waiting for a reply from the hub supplier for a more accurate description).

If it's technically acceptable and easier/possible with your current equipment, could you go full diameter bore on the hub, add a keyway and rectangular key, almost like a half key? The inner face of the key then goes against the flat of the shaft. If you permanently install the key into the hub (press fit and/or tack weld) then you're as intended fit/form/function.

Does it need to be "done right" or do you just need it to work?

I need it done right, with very specific and tight tolerances.

 

[Nescius]

Hardened steel, tight tolerances, sharp internal corners, weird shapes...all easily done with EDM.

 

[Compositepro]

Bores with keys are most often made by boring a round pilot hole and then broaching to the final shape. This requires a special broaching tool for each shape. These are readily available for standard shapes. Hardening would be done after broaching. I am trying to recall ever seeing a hardened hub.

 

[CouplingGuru]

Wire EDM, but it will be pricey. Since you have 30, maybe someone will give you a good price though.

When it comes to couplings we are always here to help.

http://WWW.PSCCOUPLINGS.COM

 

[SwinnyGG]

If you're outsourcing the job, why are you asking about process?

Draw what you need and allow your suppliers to quote. You don't care how the hole gets made, just what the final shape is.

 

[Helepolis]

If you're outsourcing the job, why are you asking about process?

I have to consider the manufacturing cost.
If it'll be to pricey to make i'll have to come up with a different solusion, which will effect other components in the system where the hub will be installed.

 

[CouplingGuru]

Helepolis,

It is going to be expensive, mainly because that feature is usually cast into the hub and it isn't a precise fit. But in order to cut it you have to either have space to get a tool in (which you don't) or EDM it.



When it comes to couplings we are always here to help.

http://WWW.PSCCOUPLINGS.COM

 

[Helepolis]

CouplingGuru,

Im not very familiar with wire EDM, only from the media and a few parts tha I played with which some of the had a closed feature cut out from the middle without any apparent guide slots or holes. At list I didn't notice any.

 

[kjoiner]

We have to create a D bore for a spool used on a capstan drive. It's not very large - for an 8mm shaft, but our machine shop uses wire EDM to create it.

Kyle

 

[SwinnyGG]

I have to consider the manufacturing cost.

I understand that you care about cost- but the quickest way to determine how much a parts costs is not to ask questions of forums about design details... the quickest method is to create a drawing detailing what you need, and send that drawing to suppliers for quoting.

 

[CouplingGuru]

The problem with the "D" hole is the corner of the "D" so you would need a very small diameter tool to get that almost sharp transition from curve to flat. That is where a Wire EDM is very good because the tool diameter is essentially the diameter of the wire which is like 0.015" approx. So you can get radii of 0.008". How does EDM work? they run a wire through your existing hole and the electrify the wire making it into a hot slicer basically. Kind of like how the cut blocks of cheese with a wire. except your are cutting metal. It is super accurate, and very versatile, but it is very slow and hard to automate. So it is fairly pricey, for instance drilling a hole 1" hole 2" deep may cost you $3, EDM the same hole and it is probably $50. That isn't including set up.

When it comes to couplings we are always here to help.

http://WWW.PSCCOUPLINGS.COM