|
Dan, 34CrNiMo6 is for hard working shafts, and easy to machine in properly sized lathe, given the right treatment is done before machining. It is NOT stainless steel, and thus, not prone to "self-hardening". Please google it.
I don't know your machining skills, but please contact a shaft machining shop (I did not say ANY machining shop) with your design at hand. This is definitely not a DIY novice job.
There seems to be a tendency to choose standard trailer wheel hub bearings lately in this forum, mostly triggered by the Thunderstruck (etc.) base plate designs. The shaft of a propeller has mostly only (bi-directional) axial forces, exept where we connect our belt pulley. A hub bearing is meant to deal with radial forces, and some axial forces. There are torsional forces too. My suggestion is to use a double roller spherical bearing, set in a proper housing. I contacted SKF (the inventor), and they recommended this bearing for this purpose. (Hmm, maybe I should mass produce a range of housings ? ;-)
For corrosion, Dan, your shaft is to be in the engine/motor room, and not submerged (I hope), so it should only be protected for exposure to humidity, like a car body. A clear Dinitrol spray will do fine. Priming and painting looks nice, but ehh, not necessary for a simple shaft, right ?!
I hope this information will be useful.
P? fre., den 26. mar. 2021 klokken 1:45, Dan Pfeiffer <dan@...> skrev:
Carsten,? That'll do.? Always good to know.? Thanks.
At first glance to my novice eye the specs the material you specified looks fairly tough to machine.? Is the comparative machining issue with SS due to work hardening??
What would you do to protect the alloy steel shaft from corrosion??
Dan Pfeiffer
?
On 2021-03-23 4:09 pm, Carsten via groups.io wrote:
?
Educated machinist at a nuclear test facility in Denmark.
Worked as production planner and programmer of CNC multiple axis lathes and milling machines for 18 years
Switched to large marine producers, writing procedures for manufacturing, and tested production methods at suppliers
Worked in Asia for 10 years, educating and teaching many of the production facilities of large Diesel engine manufacturers in South Korea and China, and assembly of engines at the shipyards
Made the crankshaft production in China feasible for them
?
Now retired (and actually tired of chinese taking over everything (because of me, partly)).
?
Is that ok for you, Dan ?
?
In short, SS is not easily machined.
Go for my selection, then you'll have an easy time at your lathe.
I'm sure that you can look up the equivalent of my material in a comparison table.
?
Cheers !
?
?
On Wednesday, 24 March 2021, 04:23:21 GMT+8, Dan Pfeiffer <dan@...> wrote:
?
?
>>Hi, Dan
>>I will suggest 34CrNiMo6 alloy for your shaft.
>>>
>>>On Friday, 19 March 2021, 07:07:01 GMT+8, Dan Pfeiffer <dan@...> wrote:
>>>Carsten, You mentioned that I should not bother with stainless steel for my small output shaft.? What would you suggest for that instead??
I found this info:
Is a 4340 a similar alloy? I can get that from McMaster.? Cost is the about the same as SS.? How hard will it machine in my lathe??? I was prepared to machine the SS.? Will this be tougher??
Also, I am figuring you have some background in all this??
Thanks, Dan Pfeiffer
?
|
Carsten,? Thanks for the useful details. I have googled it.? Many hours spent.? I should have said I was a hobbyist, not a novice.? I don't have the knowledge on materials but I have some experience with the machining.? I have a very capable Sheldon 11" lathe with the appropriate tooling for this and a Bridgeport.? Worst case is I waste the 30-$50 on a blank for some useful practice.? It is a more challenging fabrication but worth a try I think.?
The spherical bearing is very interesting.? Maybe something like this:
Not crazy expensive but there is still the housing.? And that will need to have lubrication and seals.? I'll look further into it.?? Let us know when your housing design is ready.?
Yes the shaft will be in the engine room.? No exposure to sea water unless a hose bursts.? And I am on fresh water.?
Thanks, Dan Pfeiffer
?
toggle quoted message
Show quoted text
On 2021-03-25 3:04 pm, Carsten via groups.io wrote:
Dan, 34CrNiMo6 is for hard working shafts, and easy to machine in properly sized lathe, given the right treatment is done before machining.
It is NOT stainless steel, and thus, not prone to "self-hardening".
Please google it.
?
I don't know your machining skills, but please contact a shaft machining shop (I did not say ANY machining shop) with your design at hand. This is definitely not a DIY novice job.
?
There seemailer wheel hub bearings lately in this forum, mostly triggered by the Thunderstruck (etc.) base plate designs.The shaft of a propeller has mostly only (bi-directional) axial forces, exept where we cons to be a tendency to choose standard trnect our belt pulley.
A hub bearing is meant to deal with radial forces, and some axial forces.
There are torsional forces too.
My suggestion is to use a double roller spherical bearing, set in a proper housing.
I contacted SKF (the inventor), and they recommended this bearing for this purpose.
(Hmm, maybe I should mass produce a range of housings ? ;-)
?
For corrosion, Dan, your shaft is to be in the engine/motor room, and not submerged (I hope), so it should only be protected for exposure to humidity, like a car body.
A clear Dinitrol spray will do fine.
Priming and painting looks nice, but ehh, not necessary for a simple shaft, right ?!
?
I hope this information will be useful.
P? fre., den 26. mar. 2021 klokken 1:45, Dan Pfeiffer
<dan@...> skrev:
Carsten,? That'll do.? Always good to know.? Thanks.
At first glance to my novice eye the specs the material you specified looks fairly tough to machine.? Is the comparative machining issue with SS due to work hardening??
What would you do to protect the alloy steel shaft from corrosion??
Dan Pfeiffer
?
On 2021-03-23 4:09 pm, Carsten via groups.io wrote:
?
Educated machinist at a nuclear test facility in Denmark.
Worked as production planner and programmer of CNC multiple axis lathes and milling machines for 18 years
Switched to large marine producers, writing procedures for manufacturing, and tested production methods at suppliers
Worked in Asia for 10 years, educating and teaching many of the production facilities of large Diesel engine manufacturers in South Korea and China, and assembly of engines at the shipyards
Made the crankshaft production in China feasible for them
?
Now retired (and actually tired of chinese taking over everything (because of me, partly)).
?
Is that ok for you, Dan ?
?
In short, SS is not easily machined.
Go for my selection, then you'll have an easy time at your lathe.
I'm sure that you can look up the equivalent of my material in a comparison table.
?
Cheers !
?
?
On Wednesday, 24 March 2021, 04:23:21 GMT+8, Dan Pfeiffer <dan@...> wrote:
?
?
>>Hi, Dan
>>I will suggest 34CrNiMo6 alloy for your shaft.
>>>
>>>On Friday, 19 March 2021, 07:07:01 GMT+8, Dan Pfeiffer <dan@...> wrote:
>>>Carsten, You mentioned that I should not bother with stainless steel for my small output shaft.? What would you suggest for that instead??
I found this info:
Is a 4340 a similar alloy? I can get that from McMaster.? Cost is the about the same as SS.? How hard will it machine in my lathe??? I was prepared to machine the SS.? Will this be tougher??
Also, I am figuring you have some background in all this??
Thanks, Dan Pfeiffer
?
?
?
|
Some more on thrust bearing specifications...
My boat came with a Volvo 23HP diesel and a Walter RV-10D v-drive that contained the thrust bearing.?? The Walter RV-10 is specified for 2HP/100rpm or 48hp at 2400 (the max RPM on the Volvo).? So that's about double the capacity needed with the Volvo.? The thrust bearing in the unit can be seen in this drawing.? It is part number 15 (sorry for the silly long link...).?
It is a double row angular contact ball bearing type 5304.??
The bearings in the trailer hub I have been considering are L68149 and L44649 tapered roller bearings.??
I found some load specs on all these bearings in this document:
Basic Load Ratings (radial) ?? type?? - ??? ? ? ? ? ? Cr?? ? ? ? ?? ? - ?????? C0r ? 5304? - 24,600N (5530lbs) -? 15,000N (3372lbs)???? v-drive 68149 ? - 35,000N (7868lbs)? - 47,000 (10,566lbs) trailer hub large 44649? -? 27,600 (6204lbs)? - ? 32,000 (7193lbs) trailer hub small The second figure is a static load rating.? I also found this regarding axial loads in deep groove ball bearings: Deep groove ball bearings by nature of their design can carry axial loads either alone or in combination with radialloads. Axial load capacity of standard bearings is 0.5 times the Basic Static Load Rating, CO of that bearing. Smaller bearings should not be subject to a load greater than 0.25 times CO. Excessive axial loads can lead to serious reduction of bearing I am not sure how all this relates to the bearings in the trailer hub or v-drive but I am thinking the bearings in the trailer hub are at least as strong as the bearing in my v-drive. ? The trailer bearings are tapered roller bearings which I think are supposed to be better suited than the ball bearings for axial loads?? I don't know if that makes the trailer hub assembly a reasonable thrust bearing or not.? But at least the bearings are up to the task? ? And from this is it possible that the trailer hub is actually stronger as a thrust bearing unit than the v-drive that was running in my boat for 43 years? ??? I am sure there is more to it all than that.? But there are some numbers to consider.? But, another relevant consideration with the comparison between the angular contact bearings (v-drive) and tapered bearings (trailer hub) is friction.? The angular contact are lower friction and in a housing set up to run in oil rather than grease (my v drive is filled with 30wt oil) maybe they would be a better choice with less power lost between the electric motor and the prop.?? Now we just need an appropriate housing.? And that's really what the trailer hub was about.? Are the double roller spherical bearings something in between the roller and the angular contact?? I don't know the answers to these questions but I'll keep researching.? Dan Pfeiffer
toggle quoted message
Show quoted text
On 2021-03-25 5:17 pm, Dan Pfeiffer wrote:
Carsten,? Thanks for the useful details. I have googled it.? Many hours spent.? I should have said I was a hobbyist, not a novice.? I don't have the knowledge on materials but I have some experience with the machining.? I have a very capable Sheldon 11" lathe with the appropriate tooling for this and a Bridgeport.? Worst case is I waste the 30-$50 on a blank for some useful practice.? It is a more challenging fabrication but worth a try I think.?
The spherical bearing is very interesting.? Maybe something like this:
Not crazy expensive but there is still the housing.? And that will need to have lubrication and seals.? I'll look further into it.?? Let us know when your housing design is ready.?
Yes the shaft will be in the engine room.? No exposure to sea water unless a hose bursts.? And I am on fresh water.?
Thanks, Dan Pfeiffer
?
On 2021-03-25 3:04 pm, Carsten via groups.io wrote:
Dan, 34CrNiMo6 is for hard working shafts, and easy to machine in properly sized lathe, given the right treatment is done before machining.
It is NOT stainless steel, and thus, not prone to "self-hardening".
Please google it.
?
I don't know your machining skills, but please contact a shaft machining shop (I did not say ANY machining shop) with your design at hand. This is definitely not a DIY novice job.
?
There seemailer wheel hub bearings lately in this forum, mostly triggered by the Thunderstruck (etc.) base plate designs.The shaft of a propeller has mostly only (bi-directional) axial forces, exept where we cons to be a tendency to choose standard trnect our belt pulley.
A hub bearing is meant to deal with radial forces, and some axial forces.
There are torsional forces too.
My suggestion is to use a double roller spherical bearing, set in a proper housing.
I contacted SKF (the inventor), and they recommended this bearing for this purpose.
(Hmm, maybe I should mass produce a range of housings ? ;-)
?
For corrosion, Dan, your shaft is to be in the engine/motor room, and not submerged (I hope), so it should only be protected for exposure to humidity, like a car body.
A clear Dinitrol spray will do fine.
Priming and painting looks nice, but ehh, not necessary for a simple shaft, right ?!
?
I hope this information will be useful.
?
|
Dan, Carsten and others,
I'm in somewhat of the same boat as Dan, considering the trailer hub.? I was (and still am) concerned about the forces -- trailer hubs are designed for PRIMARILY radial forces with a considerable amount of axial forces during turns. Here's my thinking...?
My motor can generate around 2000 pounds of axial thrust (100 HP). A 7,000 pound trailer hub is built for 3,500 pounds of radial thrust. Now, that's a gross miscalculation, I know. But it's a starting point. The hub can handle substantially higher loads, but those are the loads that the hub and bearings are rated for, assuming long term usage. Since the hub isn't built for axial loads, I went to dive into the bearings. Using the calculator at??I got this:?
Dynamic Load Rating for each bearing in the system, converted from kN to lb f, is conservatively 20,000 lb f and 13,000 lb f (forward and reverse). Now, according to a calculation I found online Force = x*radial +y*axial where x and y are scaling factors. x is generally 1 and y is provided by the bearing manufacturer. As best I can tell, and there was a lot of confusion in my mind, for the bearings above the y is 1.8 (which implies that they hand radial forces better than axial forces). Now, another thing I read says that x can be .67 is the axial forces are much bigger than radial forces.? So, that implies that for the the bigger bearing we have: 20,000 = 0.67*axial + 1.8*radial.? Now, if I assume that I have already taken that into account with the .67 and 1.8, then I'm at about 1/3 as strong, and that makes sense. In that case, with limited radial forces, the bearing can run at normal usage with around 1,000 lb f and get it's full lifespan. The bearings themselves can take an order of magnitude more force for periods of time without issue (like when a loaded trailer goes over a speed bump), and I'll be running at or below 1000 pounds of force in normal operation. (Higher than that will take too much battery drain for my liking.)
Now, a proper bearing, built for axial thrust would, for less money, take 5-6 times as much axial force with ease.? BUT, and here's my biggest concern, I don't know how to engineer one of those effectively. And my fear is that my jerry-rigged solution would be less effective in reality than it would be in theory. And a trailer hub, despite its many issues, is engineered by someone who has to make sure they will survive being used aggressively on dirt roads and the like. That's what's keeping me in the trailer hub space, at least for now.
Finally, slamming the boat into reverse is my #1 expected hard usage. If I put all 2,000 lb f that I can produce into the water, I'm over the normal use limits considerably, but nowhere near the 20-50,000 lb-f limits to deform the bearings or cause damage -- just experiencing excess wear.
Last thought. I'm only really pushing the boat at 300 lb-f so there's a pretty big margin there for general use, and I'm a very light user, so there's that.? Still, everything on the boat is built to last and built at the top end (for 30 years ago). I hate to 'hack' something together, but I also want to be sure I'm using components that are tested.?
That's my current thinking, Carsten (and Dan).
|
I will just give an interesting other point of view. Not sure if I can really recommend it, but for me it works. When I bought my boat it came with a 55hp yanmar. On the shaft just behind the gearbox was a ucfl 207 bearing mounted. It is not necessarily built mainly for axial forces, but it can handle them. Since it has been on this boat for 1500 engine hours and still working I decided to use the same bearing for the electric installation. I have the me1616 watercooled motor from thunderstruck running for half a year and until now it works perfectly for me. It makes the installation very easy, and if the bearing fails it's cheaper than the price of an impeller. Maybe worth a thought. Most of my motoring is done at low speeds (as probably most of us) I find the sweet spot at 30 to 40 amps which gives me 3.5 to 4 knots.?
Interested read nonetheless about all the bearings.?
Egbert
On Sat, 27 Mar 2021, 04:56 Steven Borg, <steve@...> wrote:
Dan, Carsten and others,
I'm in somewhat of the same boat as Dan, considering the trailer hub.? I was (and still am) concerned about the forces -- trailer hubs are designed for PRIMARILY radial forces with a considerable amount of axial forces during turns. Here's my thinking...?
My motor can generate around 2000 pounds of axial thrust (100 HP). A 7,000 pound trailer hub is built for 3,500 pounds of radial thrust. Now, that's a gross miscalculation, I know. But it's a starting point. The hub can handle substantially higher loads, but those are the loads that the hub and bearings are rated for, assuming long term usage. Since the hub isn't built for axial loads, I went to dive into the bearings. Using the calculator at??I got this:?
Dynamic Load Rating for each bearing in the system, converted from kN to lb f, is conservatively 20,000 lb f and 13,000 lb f (forward and reverse). Now, according to a calculation I found online Force = x*radial +y*axial where x and y are scaling factors. x is generally 1 and y is provided by the bearing manufacturer. As best I can tell, and there was a lot of confusion in my mind, for the bearings above the y is 1.8 (which implies that they hand radial forces better than axial forces). Now, another thing I read says that x can be .67 is the axial forces are much bigger than radial forces.? So, that implies that for the the bigger bearing we have: 20,000 = 0.67*axial + 1.8*radial.? Now, if I assume that I have already taken that into account with the .67 and 1.8, then I'm at about 1/3 as strong, and that makes sense. In that case, with limited radial forces, the bearing can run at normal usage with around 1,000 lb f and get it's full lifespan. The bearings themselves can take an order of magnitude more force for periods of time without issue (like when a loaded trailer goes over a speed bump), and I'll be running at or below 1000 pounds of force in normal operation. (Higher than that will take too much battery drain for my liking.)
Now, a proper bearing, built for axial thrust would, for less money, take 5-6 times as much axial force with ease.? BUT, and here's my biggest concern, I don't know how to engineer one of those effectively. And my fear is that my jerry-rigged solution would be less effective in reality than it would be in theory. And a trailer hub, despite its many issues, is engineered by someone who has to make sure they will survive being used aggressively on dirt roads and the like. That's what's keeping me in the trailer hub space, at least for now.
Finally, slamming the boat into reverse is my #1 expected hard usage. If I put all 2,000 lb f that I can produce into the water, I'm over the normal use limits considerably, but nowhere near the 20-50,000 lb-f limits to deform the bearings or cause damage -- just experiencing excess wear.
Last thought. I'm only really pushing the boat at 300 lb-f so there's a pretty big margin there for general use, and I'm a very light user, so there's that.? Still, everything on the boat is built to last and built at the top end (for 30 years ago). I hate to 'hack' something together, but I also want to be sure I'm using components that are tested.?
That's my current thinking, Carsten (and Dan).
|
The double spherical roller bearing from grainger looks fine. Even a smaller bearing than the shown will be fine for your 12KW motor...
I found an old thread in boatdesign.net. Please see reply #6 from the honorable Mike Johns:
I guess not feasible to make housings, when they already exist. In the above thread, there are suggestions for housings too. If in doubt, call SKF tech. dept. They are actually nice guys !
For ease of lubrication, they make these bearings in sealed versions too.
I would be happy by fixing the housing to the base plate properly aligned with shims (or ChockFast), and thus avoid a flexible coupling. (The belt drive should be flexible enough in itself.)
However, it takes a sturdy design of frame and base plate.
In my case, I will first try to modify my old saildrive to avoid a change to shaft drive (hellofwork).
Dan, from your photo, your lathe seems to be underpowered for this kind of shaft turning, IMHO.
On Friday, 26 March 2021, 23:07:08 GMT+8, Dan Pfeiffer <dan@...> wrote:
Some more on thrust bearing specifications...
My boat came with a Volvo 23HP diesel and a Walter RV-10D v-drive that contained the thrust bearing.?? The Walter RV-10 is specified for 2HP/100rpm or 48hp at 2400 (the max RPM on the Volvo).? So that's about double the capacity needed with the Volvo.? The thrust bearing in the unit can be seen in this drawing.? It is part number 15 (sorry for the silly long link...).?
It is a double row angular contact ball bearing type 5304.??
The bearings in the trailer hub I have been considering are L68149 and L44649 tapered roller bearings.??
I found some load specs on all these bearings in this document:
Basic Load Ratings (radial) ?? type?? - ??? ? ? ? ? ? Cr?? ? ? ? ?? ? - ?????? C0r ? 5304? - 24,600N (5530lbs) -? 15,000N (3372lbs)???? v-drive 68149 ? - 35,000N (7868lbs)? - 47,000 (10,566lbs) trailer hub large 44649? -? 27,600 (6204lbs)? - ? 32,000 (7193lbs) trailer hub small The second figure is a static load rating.? I also found this regarding axial loads in deep groove ball bearings: Deep groove ball bearings by nature of their design can carry axial loads either alone or in combination with radialloads. Axial load capacity of standard bearings is 0.5 times the Basic Static Load Rating, CO of that bearing. Smaller bearings should not be subject to a load greater than 0.25 times CO. Excessive axial loads can lead to serious reduction of bearing I am not sure how all this relates to the bearings in the trailer hub or v-drive but I am thinking the bearings in the trailer hub are at least as strong as the bearing in my v-drive. ? The trailer bearings are tapered roller bearings which I think are supposed to be better suited than the ball bearings for axial loads?? I don't know if that makes the trailer hub assembly a reasonable thrust bearing or not.? But at least the bearings are up to the task? ? And from this is it possible that the trailer hub is actually stronger as a thrust bearing unit than the v-drive that was running in my boat for 43 years? ??? I am sure there is more to it all than that.? But there are some numbers to consider.? But, another relevant consideration with the comparison between the angular contact bearings (v-drive) and tapered bearings (trailer hub) is friction.? The angular contact are lower friction and in a housing set up to run in oil rather than grease (my v drive is filled with 30wt oil) maybe they would be a better choice with less power lost between the electric motor and the prop.?? Now we just need an appropriate housing.? And that's really what the trailer hub was about.? Are the double roller spherical bearings something in between the roller and the angular contact?? I don't know the answers to these questions but I'll keep researching.? Dan Pfeiffer
On 2021-03-25 5:17 pm, Dan Pfeiffer wrote:
Carsten,? Thanks for the useful details. I have googled it.? Many hours spent.? I should have said I was a hobbyist, not a novice.? I don't have the knowledge on materials but I have some experience with the machining.? I have a very capable Sheldon 11" lathe with the appropriate tooling for this and a Bridgeport.? Worst case is I waste the 30-$50 on a blank for some useful practice.? It is a more challenging fabrication but worth a try I think.?
The spherical bearing is very interesting.? Maybe something like this:
Not crazy expensive but there is still the housing.? And that will need to have lubrication and seals.? I'll look further into it.?? Let us know when your housing design is ready.?
Yes the shaft will be in the engine room.? No exposure to sea water unless a hose bursts.? And I am on fresh water.?
Thanks, Dan Pfeiffer
?
On 2021-03-25 3:04 pm, Carsten via groups.io wrote:
Dan, 34CrNiMo6 is for hard working shafts, and easy to machine in properly sized lathe, given the right treatment is done before machining.
It is NOT stainless steel, and thus, not prone to "self-hardening".
Please google it.
?
I don't know your machining skills, but please contact a shaft machining shop (I did not say ANY machining shop) with your design at hand. This is definitely not a DIY novice job.
?
There seemailer wheel hub bearings lately in this forum, mostly triggered by the Thunderstruck (etc.) base plate designs.The shaft of a propeller has mostly only (bi-directional) axial forces, exept where we cons to be a tendency to choose standard trnect our belt pulley.
A hub bearing is meant to deal with radial forces, and some axial forces.
There are torsional forces too.
My suggestion is to use a double roller spherical bearing, set in a proper housing.
I contacted SKF (the inventor), and they recommended this bearing for this purpose.
(Hmm, maybe I should mass produce a range of housings ? ;-)
?
For corrosion, Dan, your shaft is to be in the engine/motor room, and not submerged (I hope), so it should only be protected for exposure to humidity, like a car body.
A clear Dinitrol spray will do fine.
Priming and painting looks nice, but ehh, not necessary for a simple shaft, right ?!
?
I hope this information will be useful.
?
|
On Thu, Mar 25, 2021 at 01:04 PM, Carsten wrote:
I contacted SKF (the inventor), and they recommended this bearing for this purpose.
(Hmm, maybe I should mass produce a range of housings ? ;-)
Carsten, That would actually be a great idea!? Not likely to a huge scale, but there are a few of us wanting to use a good thrust bearing / thrust plate solution. I would certainly buy one that was priced effectively and wasn't overbuilt for my purposes. I see the high end ones on the market, but I don't have a problem with noise -- at all.? And what I really want is a reliable solution that I can attach to my propeller shaft, then to a thrust plate I can attach to my motor mount / stay. Don't know the price range, but if the housing, attachments and bearings could be had for around $300 - $500, that would be fantastic.? Maybe even more. :-) Steve
|
Great info in that thread from Boatdesign.net but no conclusions for smaller vessels (<12T).?? Most of the links in the thread are old and go to 404.? But still useful stuff.
This stood out in the Mike Johns reply #6:
-----
It would be nice to find a commercial bearing housing for two
tapered roller bearings and seals. But there are only the high
end marketed products mentioned before and they are
probably not much better than the spherical roller bearing.
-----
Isn't the trailer hub a housing for two tapered roller bearings and seals??
With regard to the double spherical roller bearing, if there is a suitable sized sealed version and a suitable housing could be found would this be a reasonable choice?? We are talking about RPM max of about 1000.? Will the sealed version hold up for this application???
Or maybe the double angular contact bearing like what is in my V-drive would be a good choice.? I do see those in sealed versions.? Like this:
If the axial load capacity on this is .5x the static load rating (as I saw referenced for deep groove ball bearings) then this 5208 is good for about 3500lbs.? Even at .3x its at 2200lbs which should be about a 4x margin with a 12kW motor?? It would not be difficult to make a housing block for one of these from aluminum.? I am thinking at least 1/2" of meat in the aluminum. How would that compare to an aluminum cased transmission like a ZF for strength?? They are housing thrust bearings in aluminum cases after all.? Here is a typical example:
These ucfl 207 bearing look interesting but that flange does not look like it holds/retains the bearing for thrust loads.? Maybe some of them do.? They need to in both directions or you need two of them, one on each side of the mounting plate.
I'll give the machining of the shaft a try.? I'll let you know how it goes.? From my experience with this lathe I think it is up to the task.? It is not a typical wee hobbyist machine.? I tend to be quite conservative in depth of cut.? And it's not that large a piece.?
Dan Pfeiffer
?
toggle quoted message
Show quoted text
On 2021-03-27 10:12 am, Carsten via groups.io wrote:
?
The double spherical roller bearing from grainger looks fine.
Even a smaller bearing than the shown will be fine for your 12KW motor...
?
I found an old thread in boatdesign.net. Please see reply #6 from the honorable Mike Johns:
?
I guess not feasible to make housings, when they already exist.
In the above thread, there are suggestions for housings too.
If in doubt, call SKF tech. dept. They are actually nice guys !
For ease of lubrication, they make these bearings in sealed versions too.
?
I would be happy by fixing the housing to the base plate properly aligned with shims (or ChockFast), and thus avoid a flexible coupling. (The belt drive should be flexible enough in itself.)
However, it takes a sturdy design of frame and base plate.
?
In my case, I will first try to modify my old saildrive to avoid a change to shaft drive (hellofwork).
?
Dan, from your photo, your lathe seems to be underpowered for this kind of shaft turning, IMHO.
?
?
On Friday, 26 March 2021, 23:07:08 GMT+8, Dan Pfeiffer <dan@...> wrote:
?
?
Some more on thrust bearing specifications...
My boat came with a Volvo 23HP diesel and a Walter RV-10D v-drive that contained the thrust bearing.?? The Walter RV-10 is specified for 2HP/100rpm or 48hp at 2400 (the max RPM on the Volvo).? So that's about double the capacity needed with the Volvo.? The thrust bearing in the unit can be seen in this drawing.? It is part number 15 (sorry for the silly long link...).?
It is a double row angular contact ball bearing type 5304.??
The bearings in the trailer hub I have been considering are L68149 and L44649 tapered roller bearings.??
I found some load specs on all these bearings in this document:
Basic Load Ratings (radial) ?? type?? - ??? ? ? ? ? ? Cr?? ? ? ? ?? ? - ?????? C0r ? 5304? - 24,600N (5530lbs) -? 15,000N (3372lbs)???? v-drive 68149 ? - 35,000N (7868lbs)? - 47,000 (10,566lbs) trailer hub large 44649? -? 27,600 (6204lbs)? - ? 32,000 (7193lbs) trailer hub small The second figure is a static load rating.? I also found this regarding axial loads in deep groove ball bearings: Deep groove ball bearings by nature of their design can carry axial loads either alone or in combination with radialloads. Axial load capacity of standard bearings is 0.5 times the Basic Static Load Rating, CO of that bearing. Smaller bearings should not be subject to a load greater than 0.25 times CO. Excessive axial loads can lead to serious reduction of bearing I am not sure how all this relates to the bearings in the trailer hub or v-drive but I am thinking the bearings in the trailer hub are at least as strong as the bearing in my v-drive. ? The trailer bearings are tapered roller bearings which I think are supposed to be better suited than the ball bearings for axial loads?? I don't know if that makes the trailer hub assembly a reasonable thrust bearing or not.? But at least the bearings are up to the task? ? And from this is it possible that the trailer hub is actually stronger as a thrust bearing unit than the v-drive that was running in my boat for 43 years? ??? I am sure there is more to it all than that.? But there are some numbers to consider.? But, another relevant consideration with the comparison between the angular contact bearings (v-drive) and tapered bearings (trailer hub) is friction.? The angular contact are lower friction and in a housing set up to run in oil rather than grease (my v drive is filled with 30wt oil) maybe they would be a better choice with less power lost between the electric motor and the prop.?? Now we just need an appropriate housing.? And that's really what the trailer hub was about.? Are the double roller spherical bearings something in between the roller and the angular contact?? I don't know the answers to these questions but I'll keep researching.? Dan Pfeiffer
On 2021-03-25 5:17 pm, Dan Pfeiffer wrote:
Carsten,? Thanks for the useful details. I have googled it.? Many hours spent.? I should have said I was a hobbyist, not a novice.? I don't have the knowledge on materials but I have some experience with the machining.? I have a very capable Sheldon 11" lathe with the appropriate tooling for this and a Bridgeport.? Worst case is I waste the 30-$50 on a blank for some useful practice.? It is a more challenging fabrication but worth a try I think.?
The spherical bearing is very interesting.? Maybe something like this:
Not crazy expensive but there is still the housing.? And that will need to have lubrication and seals.? I'll look further into it.?? Let us know when your housing design is ready.?
Yes the shaft will be in the engine room.? No exposure to sea water unless a hose bursts.? And I am on fresh water.?
Thanks, Dan Pfeiffer
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On 2021-03-25 3:04 pm, Carsten via groups.io wrote:
Dan, 34CrNiMo6 is for hard working shafts, and easy to machine in properly sized lathe, given the right treatment is done before machining.
It is NOT stainless steel, and thus, not prone to "self-hardening".
Please google it.
?
I don't know your machining skills, but please contact a shaft machining shop (I did not say ANY machining shop) with your design at hand. This is definitely not a DIY novice job.
?
There seemailer wheel hub bearings lately in this forum, mostly triggered by the Thunderstruck (etc.) base plate designs.The shaft of a propeller has mostly only (bi-directional) axial forces, exept where we cons to be a tendency to choose standard trnect our belt pulley.
A hub bearing is meant to deal with radial forces, and some axial forces.
There are torsional forces too.
My suggestion is to use a double roller spherical bearing, set in a proper housing.
I contacted SKF (the inventor), and they recommended this bearing for this purpose.
(Hmm, maybe I should mass produce a range of housings ? ;-)
?
For corrosion, Dan, your shaft is to be in the engine/motor room, and not submerged (I hope), so it should only be protected for exposure to humidity, like a car body.
A clear Dinitrol spray will do fine.
Priming and painting looks nice, but ehh, not necessary for a simple shaft, right ?!
?
I hope this information will be useful.
?
?
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I looked at the specs of the ucfl bearing at the skf site and did the math. The axial load range is more than sufficient for my 12kw motor. Radial load 15kn of which 20% can be used as axial load force. It's not a huge margin, but as it is a very cheap and easy to change bearing I'm happy with?that. On this site they weirdly enough don't mention the 20% axial load , but they give tips to increase the axial load capability.?
On the end of this written piece they link to plummer block housings with spherical bearings. Isn't this what you?are looking for?
On Mon, 29 Mar 2021, 17:06 Dan Pfeiffer, < dan@...> wrote:
Great info in that thread from Boatdesign.net but no conclusions for smaller vessels (<12T).?? Most of the links in the thread are old and go to 404.? But still useful stuff.
This stood out in the Mike Johns reply #6:
-----
It would be nice to find a commercial bearing housing for two
tapered roller bearings and seals. But there are only the high
end marketed products mentioned before and they are
probably not much better than the spherical roller bearing.
-----
Isn't the trailer hub a housing for two tapered roller bearings and seals??
With regard to the double spherical roller bearing, if there is a suitable sized sealed version and a suitable housing could be found would this be a reasonable choice?? We are talking about RPM max of about 1000.? Will the sealed version hold up for this application???
Or maybe the double angular contact bearing like what is in my V-drive would be a good choice.? I do see those in sealed versions.? Like this:
If the axial load capacity on this is .5x the static load rating (as I saw referenced for deep groove ball bearings) then this 5208 is good for about 3500lbs.? Even at .3x its at 2200lbs which should be about a 4x margin with a 12kW motor?? It would not be difficult to make a housing block for one of these from aluminum.? I am thinking at least 1/2" of meat in the aluminum. How would that compare to an aluminum cased transmission like a ZF for strength?? They are housing thrust bearings in aluminum cases after all.? Here is a typical example:
These ucfl 207 bearing look interesting but that flange does not look like it holds/retains the bearing for thrust loads.? Maybe some of them do.? They need to in both directions or you need two of them, one on each side of the mounting plate.
I'll give the machining of the shaft a try.? I'll let you know how it goes.? From my experience with this lathe I think it is up to the task.? It is not a typical wee hobbyist machine.? I tend to be quite conservative in depth of cut.? And it's not that large a piece.?
Dan Pfeiffer
?
On 2021-03-27 10:12 am, Carsten via wrote:
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The double spherical roller bearing from grainger looks fine.
Even a smaller bearing than the shown will be fine for your 12KW motor...
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I found an old thread in . Please see reply #6 from the honorable Mike Johns:
?
I guess not feasible to make housings, when they already exist.
In the above thread, there are suggestions for housings too.
If in doubt, call SKF tech. dept. They are actually nice guys !
For ease of lubrication, they make these bearings in sealed versions too.
?
I would be happy by fixing the housing to the base plate properly aligned with shims (or ChockFast), and thus avoid a flexible coupling. (The belt drive should be flexible enough in itself.)
However, it takes a sturdy design of frame and base plate.
?
In my case, I will first try to modify my old saildrive to avoid a change to shaft drive (hellofwork).
?
Dan, from your photo, your lathe seems to be underpowered for this kind of shaft turning, IMHO.
?
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On Friday, 26 March 2021, 23:07:08 GMT+8, Dan Pfeiffer < dan@...> wrote: ?
?
Some more on thrust bearing specifications...
My boat came with a Volvo 23HP diesel and a Walter RV-10D v-drive that contained the thrust bearing.?? The Walter RV-10 is specified for 2HP/100rpm or 48hp at 2400 (the max RPM on the Volvo).? So that's about double the capacity needed with the Volvo.? The thrust bearing in the unit can be seen in this drawing.? It is part number 15 (sorry for the silly long link...).?
It is a double row angular contact ball bearing type 5304.??
The bearings in the trailer hub I have been considering are L68149 and L44649 tapered roller bearings.??
I found some load specs on all these bearings in this document:
Basic Load Ratings (radial) ?? type?? - ??? ? ? ? ? ? Cr?? ? ? ? ?? ? - ?????? C0r ? 5304? - 24,600N (5530lbs) -? 15,000N (3372lbs)???? v-drive 68149 ? - 35,000N (7868lbs)? - 47,000 (10,566lbs) trailer hub large 44649? -? 27,600 (6204lbs)? - ? 32,000 (7193lbs) trailer hub small The second figure is a static load rating.? I also found this regarding axial loads in deep groove ball bearings: Deep groove ball bearings by nature of their design can carry axial loads either alone or in combination with radialloads. Axial load capacity of standard bearings is 0.5 times the Basic Static Load Rating, CO of that bearing. Smaller bearings should not be subject to a load greater than 0.25 times CO. Excessive axial loads can lead to serious reduction of bearing I am not sure how all this relates to the bearings in the trailer hub or v-drive but I am thinking the bearings in the trailer hub are at least as strong as the bearing in my v-drive. ? The trailer bearings are tapered roller bearings which I think are supposed to be better suited than the ball bearings for axial loads?? I don't know if that makes the trailer hub assembly a reasonable thrust bearing or not.? But at least the bearings are up to the task? ? And from this is it possible that the trailer hub is actually stronger as a thrust bearing unit than the v-drive that was running in my boat for 43 years? ??? I am sure there is more to it all than that.? But there are some numbers to consider.? But, another relevant consideration with the comparison between the angular contact bearings (v-drive) and tapered bearings (trailer hub) is friction.? The angular contact are lower friction and in a housing set up to run in oil rather than grease (my v drive is filled with 30wt oil) maybe they would be a better choice with less power lost between the electric motor and the prop.?? Now we just need an appropriate housing.? And that's really what the trailer hub was about.? Are the double roller spherical bearings something in between the roller and the angular contact?? I don't know the answers to these questions but I'll keep researching.? Dan Pfeiffer
On 2021-03-25 5:17 pm, Dan Pfeiffer wrote:
Carsten,? Thanks for the useful details. I have googled it.? Many hours spent.? I should have said I was a hobbyist, not a novice.? I don't have the knowledge on materials but I have some experience with the machining.? I have a very capable Sheldon 11" lathe with the appropriate tooling for this and a Bridgeport.? Worst case is I waste the 30-$50 on a blank for some useful practice.? It is a more challenging fabrication but worth a try I think.?
The spherical bearing is very interesting.? Maybe something like this:
Not crazy expensive but there is still the housing.? And that will need to have lubrication and seals.? I'll look further into it.?? Let us know when your housing design is ready.?
Yes the shaft will be in the engine room.? No exposure to sea water unless a hose bursts.? And I am on fresh water.?
Thanks, Dan Pfeiffer
?
On 2021-03-25 3:04 pm, Carsten via wrote:
Dan, 34CrNiMo6 is for hard working shafts, and easy to machine in properly sized lathe, given the right treatment is done before machining.
It is NOT stainless steel, and thus, not prone to "self-hardening".
Please google it.
?
I don't know your machining skills, but please contact a shaft machining shop (I did not say ANY machining shop) with your design at hand. This is definitely not a DIY novice job.
?
There seemailer wheel hub bearings lately in this forum, mostly triggered by the Thunderstruck (etc.) base plate designs.The shaft of a propeller has mostly only (bi-directional) axial forces, exept where we cons to be a tendency to choose standard trnect our belt pulley.
A hub bearing is meant to deal with radial forces, and some axial forces.
There are torsional forces too.
My suggestion is to use a double roller spherical bearing, set in a proper housing.
I contacted SKF (the inventor), and they recommended this bearing for this purpose.
(Hmm, maybe I should mass produce a range of housings ? ;-)
?
For corrosion, Dan, your shaft is to be in the engine/motor room, and not submerged (I hope), so it should only be protected for exposure to humidity, like a car body.
A clear Dinitrol spray will do fine.
Priming and painting looks nice, but ehh, not necessary for a simple shaft, right ?!
?
I hope this information will be useful.
?
?
|
