20 replies to this topic

[Alchemist]

I tried  a search but did not find an answer, so I'd like to ask what type of metal is the armature shaft made of please?

 

Thank you.

 

Ernie

[Jaeger Team]

I guess HSS (high speed steel) hardened

[zipper]

Steel enhanced with Carbon, Tungsten, Molybdenum, Chromium, Vanadium, Cobalt for instance. HSS "drill/reamer blanks".

[don.siegel]

I believe that HSS is high-strength steel, not high speed... 

 

Don 

[havlicek]

Hi Ernie, I'm kind of surprised you hadn't known this, but all armature shafts (*at least for the motors we're interested in) are made from various steel alloys.  These range from mild ("soft") to hardened high-carbon and even some stainless alloys.  To me, the hardness is not as important as the "straightness" of a shaft, and people get fixated on the whole "drill-blank" shaft thing (*which is pretty vague), when how true a shaft runs is critical.  In other words, a drill blank shaft isn't necessarily a good shaft.

During the "Mabuchi Can Era", none of those motors had hardened shafts, and none of the current disposable Chinese-manufactured armatures I'm aware of do either, but most seem to be (*or were, in the case of the Mabuchis) fine.  The larger (*and bizarrely-dimensioned)  36D shafts were both generally very straight and strong due to their larger cross section, while still being a "soft steel".  The newer Mabuchi motors meant for general industrial-type uses of that "36D" size (*although now "full-round" type motors) still use the same weird size shafts, and they are still very good as far as "straightness".

You didn't ask, but sizing also matters a lot, and a difference of a ten thousandth or so can mean the difference between "go and no-go" with ball bearings, although not so much with bushings and/or oilites.  Most modern shafts supplied with motors are sized to fit bearings, but for the rare individual who actually presses their own arm blanks, there ARE 2mm shafts still out there that need to be polished-down to fit as people used to have to do in the old days.

Back on shaft alloys, there is this idea out there that hardened shafts can't be bent...that they will simply snap.  That is not true.

[Dave Crevie]

HSS does indeed mean "high speed steel". Long ago metal cutting tools were made from hardened carbon steel. These tools didn't

wear well, and had to be changed or resharpened frequently. This also meant that the cutting speeds for these tools were necessarily

slow to avoid "burning" the edge, softening the steel. As metalurgy progressed new alloys were developed which made better cutting

tools, which could be used at higher cutting speeds, making shorter machining times. These grades of steel became commonly known

as "high speed alloys" because their cutting speeds were greatly enhanced. 

[MSwiss]

Ernie,
What is the genesis of your question?

[Alchemist]

Hi John,

 

Hi Ernie, I'm kind of surprised you hadn't known this, but all armature shafts (*at least for the motors we're interested in) are made from various steel alloys. 

 

Too much phenolic dust John - LOL   Thank you for the info.

 

Yes I was aware of the variance of materials, but wanted to inquire if there was an "industry standard" of a specific type of metal employed for armature usage.

 

Your input is always appreciated!

 

Thank you much John!

 

 

Hi Mike,

 

Ernie,

What is the genesis of your question? 

 

The purpose of my inquiry is that depending on the armature metal (stainless vs carbon steel)  would dictate the type of retaining compound I would employ for my my "Direct Drive" project.

 

Thank you.

 

Ernie

[MSwiss]

What are you going to Loctite to the shaft?

[Alchemist]

Mike,

 

LOL!    You inspired all this with your "awesome Direct Drive concept/prototype", yet I am not wanting to "disclose" too much - too soon!

 

I want to "wait and see" if this project of mine will work.

 

I'd like to "Thank you" for the inspiration and motivation (ever since you posted  that video years ago) , to excite me to finally build my own Direct Drive Slot Car.

 

Of course, this won't be your "typical DD chassis!".  LOL

 

I appreciate your inquiry though.

 

Ernie 

[Phil Hackett]

Heat treated M2, M7 and M50 steels have been used for the custom armatures. The motors coming from China aren't M2, M7 or M50 HSS....

[Alchemist]

Thanks Phil!

 

Ernie

[Geary Carrier]

Ernie,

 

Loctite 638 or 648 are both high strength and work on active and passive surfaces which should pretty much cover variations in shaft composition.

[Alchemist]

Thank you Geary!

 

There are other variables besides the types of metal that I also need to take into consideration.

 

I've used L638 before with very good results - I'll look into the 648 you mention.

 

I do appreciate the recommendation!

 

Thank you.

 

Ernie

[Geary Carrier]

 648-EN.pdf   80.79KB   35 downloads

 

The biggest difference between 638 and 648 is the viscosity with 638 being high and 648 low...

[Alchemist]

Thank you very much for the PDF link Geary!

 

It's appreciated.

 

Ernie

[Geary Carrier]

You're welcome Ernie...

[Dan Miller]

M2 HSS for upper class armatures, made from steel produced in North America or Japan, is a great starting point. Rockwell 62 - 63 works well. Who grinds it to size for our use is an issue to contend with. John mentioned close tolerance and a range of .0002" is fine.   

 

Ernie ......... Consider the finish of the surface of the shaft. You may be best with a crosshatch pattern to help with the bond of the Loctite. That finish is typically not produced by centerless grinding but you could create it yourself.

 

You may even think about using a softer steel and some sort of sandblasted style of finish ??? Maybe acid etched ???? Find some A2 steel close to your size and mess around with that. Might work out for you. You could bond both laminations and hubs to it if need be.

 

.

 

.

[John Secchi]

Another Loctite that works well is the 603, described on the bottle as "oil tolerant retainer, low viscosity and high strength".

Seems it is more tolerant of oil than 638 while setting, down side you need to take care to keep it away from the motor bearing as it's quite a bit thinner!

[oneofwos]

[Geary Carrier]

 603-EN.pdf   74.35KB   25 downloads

[Alchemist]

Hi Dan,

 

Thank you for the technical info - it'a appreciated!

 

John - thank you for the L603 recommendation!  

 

Geary, my Slotblog buddy - thanks for the link!

 

All the responses are appreciated - thank you very much!

 

Ernie